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Everything you need to know about Computed Tomography (CT) & CT Scanning

September 2018 Imaging Pearls - Educational Tools | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ September 2018

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Chest

    • "Cystic fibrosis (CF) is one of the most common genetic disorders in the white population, with a lethal outcome at a young age. Morbidity and mortality in patients with CF are essentially related to pulmonary disease. Early detection and follow-up of lung disease in CF is crucial to allow prompt treatment adaptation."
      Pulmonary Disease in Cystic Fibrosis: Assessment with Chest CT at Chest Radiography Dose Levels
      Caroline W. Ernst et al.
      Radiology 2014; 273:597–605
    • Cystic Fibrosis: Imaging
      • Radiation doses in chest CT can be reduced dramatically.
      • Findings suggest that, in CF, follow-up chest radiography might be replaced by chest CT without important dose penalty.
      • Diagnostic quality for patients with CF can be maintained with use of a lower dose protocol than that used with conventional CT.
    • "Early detection and follow-up of lung disease in CF is crucial to allow prompt treatment adaptation. Early changes in lung disease can be detected with various methods, such as pulmonary function testing (PFT), radiography, and com- puted tomography (CT)."
      Pulmonary Disease in Cystic Fibrosis: Assessment with Chest CT at Chest Radiography Dose Levels
      Caroline W. Ernst et al.
      Radiology 2014; 273:597–605
    • "Cystic fibrosis (CF) is the most common inherited disease in the Western world, affecting more than 30 000 individuals in the United States and 60 000 individuals worldwide. Respiratory failure continues to account for more than 80% of the deaths from this disease. However, advances in treatment have increased the median predicted survival time from 16 years in the 1970s to more than 37 years today. Adults now represent more than 40% of the total CF population."
      Emerging Roles for CT Imaging in Cystic Fibrosis
      Milene T. Saavedra, David A. Lynch
      Radiology 2009; 252:327–329
    • "CT serves as an excellent technique with which to depict morphologic abnormalities of CF, including airway wall thickening, bronchi- ectasis, mucoid impaction, centrilobular
      nodularity, and expiratory air trapping. Furthermore, several semiquantitative scoring systems of varying complexity have been developed to describe the degree of disease involvement ."
      Emerging Roles for CT Imaging in Cystic Fibrosis
      Milene T. Saavedra, David A. Lynch
      Radiology 2009; 252:327–329
    • "Pregnancy is a hypercoagulable state, and consequently pregnant patients are at high risk for PE. The diagnosis of PE can be challenging in pregnant patients, as the clinical signs and symptoms of PE can mimic the physiological effects of pregnancy. In the ATS/STR guidelines, CTPA is the recommended when a chest radiograph is abnormal and therefore maintains an important role in the evaluation of PE. While both V/Q scintigraphy and CTPA have high sensitivities and specificities, CTPA is quick to perform and interpret, and provides a higher rate of alternate diagnoses."
      Low dose computed tomography pulmonary angiography protocol for imaging pregnant patients: Can dose reduction be achieved without reducing image quality?
      Halpenny D et al.
      Clinical Imaging: Volume 44, July–August 2017, Pages 101-105
    • "CTPA image quality is potentially impacted by the hemodynamic changes of pregnancy. Increased plasma volume, cardiac output, total vascular resistance, and heart rate can lead to hemodilution of injected intravenous contrast with decreased peak arterial enhancement and shorter contrast material arrival time in the pulmonary arteries. Additionally, the gravid uterus increases IVC pressure and can accentuate transient contrast interruption."
      Low dose computed tomography pulmonary angiography protocol for imaging pregnant patients: Can dose reduction be achieved without reducing image quality?
      Halpenny D et al.
      Clinical Imaging: Volume 44, July–August 2017, Pages 101-105
    • "The thymus changes with age. Its shape and the proportion of solid tissue and fat vary between individuals, yet there is no comprehensive work describing the size and morphology of the normal thymus on CT. As a result, many adults with some preserved soft tissue in the thymus may undergo extensive work-up to exclude mediastinal tumor. "
      Normal CT characteristics of the thymus in adults
      Author links open overlay panel
      Simanovsky N et al.
      European Journal of Radiology
      Volume 81, Issue 11, November 2012, Pages 3581-3586
    • "Thymic density and volume decreased progressively with age. No solid tissue component was seen in the thymus in patients older than 54 years. In the majority of patients, the thymus had an arrowhead shape, with middle position. However, great variability in thymic shape and border were noted. There was a highly significant relationship between density and patient age (p < 0.0001). "
      Normal CT characteristics of the thymus in adults
      Author links open overlay panel
      Simanovsky N et al.
      European Journal of Radiology
      Volume 81, Issue 11, November 2012, Pages 3581-3586
    • Our study demonstrated a spectrum of appearance of a normal thymus on CT and the sex difference in the middle and older age groups. In the present cohort from the FHS with the mean age of 58.9 years, only 8% (208/2540) of overall participants had thymic glands with half or more soft-tissue parenchyma (Scores 2 and 3), and 74% (1869/2540) showed a complete fatty replacement of the thymic gland due to advanced involution."
      Normal Thymus in Adults: Appearance on CT and Associations with Age, Sex, BMI and Smoking
      Tetsuro Araki et al.
      Eur Radiol. 2016 January ; 26(1): 15–24
    • "In the present study, meticulous measurements of the thymic glands revealed that those in male were significantly larger than those in female, thus justifying the data split according to sex, providing reference values for the size of a normal thymus. However, it should be noted that thymus glands at middle and older age, especially in male, are usually not applicable for measurements because of advanced fatty degeneration with an obscured contour. Moore et al suggested that the overall size of the thymus may not change with aging in adults."
      Normal Thymus in Adults: Appearance on CT and Associations with Age, Sex, BMI and Smoking
      Tetsuro Araki et al.
      Eur Radiol. 2016 January ; 26(1): 15–24
    • "We aimed to combine previously described pregnancy specific CTPA technique alterations with a dose reduction strategy and a low kVp technique to yield a low dose CTPA protocol specifically tailored to pregnant patients, without a reduction in clinical image quality. The results demonstrate that by using a low kVp CTPA technique tailored to pregnancy, effective doses under 1 mSv are routinely achievable in a pregnant population."
      Low dose computed tomography pulmonary angiography protocol for imaging pregnant patients: Can dose reduction be achieved without reducing image quality?
      Halpenny D et al.
      Clinical Imaging: Volume 44, July–August 2017, Pages 101-105
Colon

    • "Peritonitis is the most common clinical manifestation of abdominal TB. Infection of the peritoneum is usually secondary to hematogenous spread from a pulmonary focus, from adjacent organs such as the intestine or the fallopian tube or ruptured necrotic lymph node. Liver cirrhosis, human immunodeficiency virus–positive, and chronic renal failure patients on continuous ambulatory peritoneal dialysis are at an increased risk for peritoneal TB." 
      Imaging Spectrum of Extra thoracic Tuberculosis
      Rout, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
    • "Based on the pattern of ascites, omental and peritoneal tubercles, and associated inflammatory and fibrotic response, TB peritonitis has been traditionally classified into 3 categories." 
      Imaging Spectrum of Extrathoracic Tuberculosis
      Raut, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
    • "Wet ascitic type-This is the most common variety of peritoneal TB seen among 90% of the cases with significant free or loculated high-density ascitic fluid on CT scan.".
      Imaging Spectrum of Extrathoracic Tuberculosis
      Raut, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
    • "Fibrotic fixed type-This relatively less frequent variety of peritoneal TB is characterized by mesenteric and omental thickening, tuberculous deposits, and matted bowel loops.".
      Imaging Spectrum of Extrathoracic Tuberculosis
      Raut, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
    • "Dry or 'plastic' type-his is a rare variety showing peritoneal nodules, fibrous peritoneal reaction, and dense adhesions. Ultrasonography can accurately demonstrate small quantities of loculated or free ascitic fluid. Multiple thin, complete or incomplete septae can be seen with echogenic debris being frequent in the loculated ascites. However, these features are can also be seen in malignancy, chronic infective peritonitis, and hemoperitoneum. CT scan shows loculated or free, high attenuation ascitic fluid (20–45 Hounsfield unites [HU]), omental thickening/nodularity, and thickened inflamed mesentery associated with mesenteric adenopathy."
      Imaging Spectrum of Extrathoracic Tuberculosis
      Raut, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
    • "The common routes of spread of tubercle bacilli to the gastrointestinal tract (GIT) include hematogeneous spread from the primary lung lesion, ingestion of infected sputum from active pulmonary focus, direct spread from adjacent organs, or through lymphatic spread from infected lymph nodes. Although TB can involve any part of the GIT, the most common target site of involvement is the IC region. This is likely owing to several factors, including relative stasis, abundant lymphoid tissue, and closer contact of the bacilli with the mucosa in this region."
      Imaging Spectrum of Extrathoracic Tuberculosis
      Raut, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
    • "The IC region is the most frequent site for bowel TB. The frequency of bowel involvement decreases both proximally and distally from the IC region. Multiple strictures, adhesions, and bowel obstruction are the most the most common complications. Perforation followed by fistulae formation and intestinal bleeding may be seen but are uncommon."
      Imaging Spectrum of Extrathoracic Tuberculosis
      Raut, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
    • "CT scan is the modality of choice for the evaluation of abdominal TB. Mural thickening of the IC region is frequent in GIT TB. It may be limited to the terminal ileum or caecum, or it may involve both .The thickening may be symmetric or asymmetric. Asymmetric thickening of the IC valve and medial wall of the caecum may have an exophytic extension and this may engulf the terminal ileum. Fat stranding and inflammation is seen in the pericecal region and adjacent mesentery. There may be associated bowel obstruction and/or perforation."
      Imaging Spectrum of Extrathoracic Tuberculosis
      Raut, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
    • "Hepatosplenic TB occurs secondary to hematogeneous spread of disease from active tuberculous focus elsewhere in the body. Commonly, it presents as miliary form in association with miliary pulmonary TB. Miliary TB manifests as hepatomegaly with multiple tiny low-attenuation foci without significant postcontrast enhancement on CT scan. The macronodular form of hepatosplenic TB is uncommon and manifests as a few hypodense lesions with ill-defined margins."
      Imaging Spectrum of Extrathoracic Tuberculosis
      Raut, Abhijit A. et al.
      Radiologic Clinics , Volume 54 , Issue 3 , 475 - 501
Deep Learning

    • "Most computer-based algorithms in medicine are "expert systems" — rule sets encoding knowledge on a given topic, which are applied to draw conclusions about specific clinical scenarios, such as detecting drug interactions or judging the appropriateness of obtaining imaging. Expert systems work the way an ideal medical student would: they take general principles about medicine and apply them to new patients."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "Machine learning, conversely, approaches problems as a doctor progressing through residency might: by learning rules from data. Starting with patient-level observations, algorithms sift through vast numbers of variables, looking for combinations that reliably predict outcomes."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "But where machine learning shines is in handling enormous numbers of predictors — sometimes, remarkably, more predictors than observations — and combining them in nonlinear and highly interactive ways.This capacity al- lows us to use new kinds of data, whose sheer volume or complexity would previously have made analyzing them unimaginable."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "Another key issue is the quantity and quality of input data. Machine learning algorithms are highly data hungry, often requiring millions of observations to reach acceptable performance levels. In addition, biases in data collection can substantially affect both performance and generalizability. Lactate might be a good predictor of the risk of death, for example, but only a small, nonrepresentative sample of patients have their lactate levels checked."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "Machine learning has become ubiquitous and indispensable for solving complex problems in most sciences. In astronomy, algorithms sift through millions of images from telescope surveys to classify galaxies and find supernovas."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "Increasingly, the ability to transform data into knowledge will disrupt at least three areas of medicine. First, machine learning will dramatically improve the ability of health professionals to es- tablish a prognosis. Current prognostic models (e.g., the Acute Physiology and Chronic Health Evaluation [APACHE] score and the Sequential Organ Failure Assessment [SOFA] score) are restricted to only a handful of variables, because humans must enter and tally the scores. But data could instead be drawn directly from EHRs or claims databases, allow- ing models to use thousands of rich predictor variables."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "Second, machine learning will displace much of the work of radiologists and anatomical pathologists. These physicians focus largely on interpreting digitized images, which can easily be fed directly to algorithms instead. Massive imaging data sets, com- bined with recent advances in computer vision, will drive rapid improvements in performance, and machine accuracy will soon exceed that of humans. Indeed, radiology is already partway there: algorithms can replace a second radiologist reading mammograms and will soon exceed human accuracy."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "The patient- safety movement will increasingly advocate the use of algorithms over humans — after all, algorithms need no sleep, and their vigilance is the same at 2 a.m. as at 9 a.m. Algorithms will also monitor and interpret streaming physiological data, replacing aspects of anesthesiology and criti- cal care. The time scale for these disruptions is years, not decades."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "Machine learning will become an indispensable tool for clinicians seeking to truly understand their patients. As patients’ conditions and medical technologies become more complex, the role of machine learning will grow, and clinical medicine will be challenged to grow with it."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "As in other industries, this challenge will create winners and losers in medicine. But we are optimistic that patients, whose lives and medical histories shape the algorithms, will emerge as the biggest winners as machine learning transforms clinical medicine."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016

    • Deep Learning Approach for Evaluating Knee MR Images: Achieving High Diagnostic Performance for Cartilage Lesion Detection
      FangLiu et al.
      Radiology 2018 (in press)


    • "By now, it’s almost old news: big data will transform medicine. It’s essential to remember, however, that data by themselves are useless. To be useful, data must be analyzed, interpreted, and acted on. Thus, it is algorithms —
      not data sets — that will prove transformative."
      Predicting the Future — Big Data, Machine Learning, and Clinical Medicine
      Obermeyer Z, Emanuel EJ
      N Engl J Med 375;13 September 29, 2016
    • "Deep learning–based approaches have the potential to maximize diagnostic performance for detecting cartilage degeneration and acute cartilage injury within the knee joint while reducing subjectivity, variability, and errors due to distraction and fatigue associated with human interpretation."
      Deep Learning Approach for Evaluating Knee MR Images: Achieving High Diagnostic Performance for Cartilage Lesion Detection
      FangLiu et al.
      Radiology 2018 (in press)
    • "Radiomics uses advanced image-processing techniques to extract a large number of quantitative parameters from imaging data, and its potential to improve diagnostic accuracy is increasingly being studied . Initial studies have reported promising performance of radiomics with and without the use of machine learning in the prediction of the prostate cancer Gleason score."
      Radiomic Machine Learning for Characterization of Prostate Lesions with MRI: Comparison to ADC Values
      Bonekamp D et al.
      Radiology 2018 (in press)
    • "In conclusion, this study compared the use of mean ADC and radiomics with machine learning for the characterization of lesions that were prospectively detected during routine clinical interpretation.
      Quantitative assessment of the mean ADC was more accurate than qualitative PI-RADS assessment in classifying a lesion as clinically significant prostate cancer. Radiomics provided additional data that ADC metrics (including mean ADC) were more valuable than other MRI features. In fact, at the current cohort size, no added benefit of the radiomic approach was found, and mean ADC is suggested as the best choice for quantitative prostate assessment."
      Radiomic Machine Learning for Characterization of Prostate Lesions with MRI: Comparison to ADC Values
      Bonekamp D et al.
      Radiology 2018 (in press)
    • Purpose: To determine the feasibility of using a deep learning approach to detect cartilage lesions (including cartilage softening, fibrillation, fissuring, focal defects, diffuse thinning due to cartilage degeneration, and acute cartilage injury) within the knee joint on MR images.
      Conclusion: is study demonstrated the feasibility of using a fully automated deep learning–based cartilage lesion detection system to evaluate the articular cartilage of the knee joint with high diagnostic performance and good intraobserver agreement for detecting cartilage degeneration and acute cartilage injury.
      Deep Learning Approach for Evaluating Knee MR Images: Achieving High Diagnostic Performance for Cartilage Lesion Detection
      FangLiu et al.
      Radiology 2018 (in press)
    • Purpose: To compare biparametric contrast-free radiomic machine learning (RML), mean apparent dffusion coeficient (ADC), and radiologist assessment for characterization of prostate lesions detected during prospective MRI interpretation.
      Conclusion: Quantitative measurement of the mean apparent diffusion coeficient (ADC) improved differentiation of benign versus malignant prostate lesions, compared with clinical assessment. Radiomic machine learning had comparable but not better performance than mean ADC assessment.
      Radiomic Machine Learning for Characterization of Prostate Lesions with MRI: Comparison to ADC Values
      Bonekamp D et al.
      Radiology 2018 (in press)
Esophagus

    • Intramural Hematoma
      ●      Intramural hematoma of the esophagus is a rare entity on the spectrum of esophageal injuries ranging from Mallory-Weiss tears to esophageal rupture
      ●      Most common causes:
          ○      Iatrogenic
          ○      Abrupt increase in intraluminal pressure from forceful emesis or foreign body impaction
          ○      Spontaneous, usually in the setting of coagulopathy
      ●      Majority of patients report sudden onset retrosternal chest pain, hematemesis or dysphagia/odynophagia
      ●      High clinical suspicion, in addition to rapid evaluation with MDCT are important in differentiating intramural hematoma from ACS or aortic injury
      ●      Management is most often conservative with resolution within few days to weeks
    • Pearls and Pitfalls
      ●    Mimics of tumor
           ●     Varices on noncontrast or arterial phase CT
           ●     Wall thickening due to severe esophagitis
      ●    Mimics of obstruction- dilated esophagus
          ●     Achalasia
          ●     Scleroderma
          ●     Gastric pull through or colonic interposition (check surgical history!)
    • "Zenker’s diverticulum (ZD) is a posterior phar- yngoesophageal pouch that forms through pulsion forces in an area of relative hypopharyngeal wall weakness between the oblique fibers of the inferior pharyngeal constrictor and the horizontal fibers of the cricopharyngeus (CP) muscles. Poor upper esophageal sphincter (UES) compliance is the presumed pathophysiologic mechanism of action. This dysfunction creates a high- pressure zone eventuating in increased pulsion forces and subsequent ZD formation."
      Zenker’s Diverticulum
      Ryan Law, David A. Katzka, and Todd H. Baron
      Clinical Gastroenterology and Hepatology 2014;12:1773–1782
    • "This entity most commonly presents in the elderly and can be associated with a plethora of potential symptoms, of which dysphagia is most common."
      Zenker’s Diverticulum
      Ryan Law, David A. Katzka, and Todd H. Baron
      Clinical Gastroenterology and Hepatology 2014;12:1773–1782
    • Zenkers Diverticulum: Facts
      ●    an outpouching of tissue through the Killian triangle that is believed to be caused by dysfunction of the cricopharyngeal muscle.
      ●    ZD is a relatively uncommon disorder occurring in the elderly.
      ●    The predominant symptom of ZD is dysphagia, and the most serious consequence is pulmonary aspiration.
    • "Zenker's diverticulum is an unusual site of origin for clinically significant upper gastrointestinal hemorrhage and differential diagnosis must include other more frequent causes of upper gastrointestinal bleeding. In our opinion, classicalsurgical therapy is indicated when distal esophageal imaging cannot be obtained during endoscopic examination, there is a large diverticulum or in an emergency setting when fast control over the bleeding source is required."
      Zenker's diverticulum, a rare cause of upper gastrointestinal bleeding.
      Bălălău C et al.
      Rev Med Chir Soc Med Nat Iasi. 2013 Apr-Jun;117(2):297-301.
    • "The most common complication of Zenker's diverticulum is aspiration pneumonia, compression of the trachea and esophageal obstruction with large diverticulum, and increased risk of development of carcinoma. Thus bleeding occurs rarely, can be massive and life threatening, with ulceration being the most common cause."
      Zenker's diverticulum, a rare cause of upper gastrointestinal bleeding.
      Bălălău C et al.
      Rev Med Chir Soc Med Nat Iasi. 2013 Apr-Jun;117(2):297-301.
    • Complications of Esophageal Rupture and Fistula Formation
      ●          Aortoesophageal fistula
      ●          Tracheoesophageal fistula
      ●          Chronic paraesophageal abscess as a result of remote esophageal perforation
      ●          Thoracic discitis/osteomyelitis secondary to esophageal perforation
      ●          Duplication cyst rupture into distal esophagus
    • Aortoesophageal Fistula
      ●       Rare and often fatal cause of upper gastrointestinal bleeding
      ●       Most commonly due to localized rupture of thoracic aortic aneurysm or secondary complication of aneurysm repair or graft infection
              ○      Less common causes include foreign body ingestion, esophageal malignancy and syphilis
      ●       Classic clinical triad first described by Chiari:
              ○      Dysphagia or midthoracic pain radiating to back
              ○      Sentinel hemorrhage followed by asymptomatic interval
              ○      Massive upper gastrointestinal hemorrhage leading to exsanguination
      ●      High clinical suspicion is imperative for prompt detection with MDCT, triage and successful surgical repair
      ●      MDCT is sensitive for the detection of fistula formation
              ○      Presence of focal esophageal wall thickening, extraluminal air, contrast extravasation, perianeurysmal hematoma or pseudoaneurysm should raise concern for aortoenteric fistula   
    • Tracheoesophageal Fistula
      ●          Majority of esophagorespiratory fistulas in adults are acquired
           ○     Direct invasion by intrathoracic malignancies, mainly esophageal carcinoma, account for greater than 60% of cases
                ■     Reported in up to 5-10% of patients with advanced esophageal cancer; increased risk if history of prior radiation
           ○     Other causes include prolonged intubation, foreign body ingestion, esophageal instrumentation, trauma and granulomatous infection
      ●          Suspect esophagorespiratory fistula in patients with known esophageal cancer and recurrent pneumonia
      ●          Esophagogram is usually definitive and can differentiate aspiration versus fistula
           ○     MDCT is useful if fluoroscopy is equivocal and may define malignancy or fistulous tract
      ●          Prognosis is poor with treatment often being palliative
           ○     Endobronchial stent placement, esophageal bypass via gastrostomy/jejunostomy, or surgical bypass or correction
        
    • Esophageal Vascular Malformations
      ● Esophageal hemangiomas are rare, comprising approximately 3% of all benign esophageal tumors
          ○ Prevalence of 0.04% on autopsy
      ● Subtypes: Cavernous, capillary, hamartomatous, AVM???
      ● Imaging characteristics include intramural location, well-circumscribed and lobulated mass and presence of multiple phleboliths
           ○ Most often solitary, however multiple lesions may be seen in Osler-Weber-Rendu disease or Klippel-Trénaunay syndrome
      ● Easily mistaken with esophageal leiomyoma
           ○ Distinguished by presence of phleboliths and enhancement
      ● Often asymptomatic
           ○ When symptomatic, most often associated with hemorrhage and dysphagia
      ● Surgical or endoscopic resection is performed for symptomatic cases
       
    • Esophageal Varices
      ●    "Downhill" varices are less common than the so-called "uphill varices associated with portal hypertension
      ●     Most often secondary to SVC obstruction
               ○      SVC obstruction from lung malignancy, mediastinal tumor/adenopathy, systemic vasculitis, and catheter-related thrombosis has been described
      ●    Commonly located in the upper third of the esophagus
      ●    Location of SVC obstruction in relation to azygous vein determines extent of venous collaterals
             ○      Superior to azygos-esophageal varices bypass SVC obstruction via drainage into azygos vein
             ○      Inferior to azygos-esophageal collaterals drain superior systemic system into portal vein, often involving entire thoracic segment of the esophagus
      ●   Decreased rate of variceal hemorrhage
    • Esophageal Obstruction
      •       Tumor
              •       adenocarcinoma of the gastroesophageal junction
              •       gastric cancer involving distal esophagus
      •        Stricture
             •       Sequela of severe or recalcitrant esophagitis
             •       Complication of lye ingestion
      •        Gastric volvulus
             •       Rare cause for esophageal obstruction
             •       Patients can have chronic asymptomatic gastric volvulus, but presence of acute pain, wall thickening and esophageal obstruction indicate surgical emergency
Gallbladder

    • OBJECTIVE. In 2013, a multidisciplinary group at our Veterans Administration hospital collaborated to improve the diagnosis and treatment of patients with acute cholecystitis (AC) at our facility. Our role in this project was to evaluate the diagnostic accuracies of ultrasound (US) and CT.
      CONCLUSION. CT was significantly more sensitive for diagnosing AC than US. CT and US are complementary, and the other modality should be considered if there is high clinical suspicion for AC and the results of the first examination are negative
      Comparing the Diagnostic Accuracy of Ultrasound and CT in Evaluating Acute Cholecystitis
      Wertz JR et al.
      AJR 2018; 211:W92–W97
    • RESULTS. The sensitivity of CT for detecting AC was significantly greater than that of US: 85% versus 68% (p = 0.043), respectively; however, the negative predictive values of CT and US did not differ significantly: 90% versus 77% (p = 0.24–0.26). Because there were no false-positives, the specificity and positive predictive values for both modalities were 100%. Among the 42 patients who underwent CT and US, both modalities were positive for AC in 25 patients, CT was positive and US was negative in 10 patients, and US was positive and CT was negative in two patients; in five patients, both US and CT were negative.
      Comparing the Diagnostic Accuracy of Ultrasound and CT in Evaluating Acute Cholecystitis
      Wertz JR et al.
      AJR 2018; 211:W92–W97
    • "More than 90% of patients in surgical wards are seen for one or more of the following conditions: acute appendicitis, AC, small-bowel obstruction, urinary colic, perforated peptic ulcer, acute pancreatitis, acute diverticular disease, and nonspecific non-surgical abdominal pain."
      Comparing the Diagnostic Accuracy of Ultrasound and CT in Evaluating Acute Cholecystitis
      Wertz JR et al.
      AJR 2018; 211:W92–W97
    • "US had a sensitivity of 68% (38/56) and negative predictive value (NPV) of 77% (60/78). CT had a sensitivity of 85% (41/48) and an NPV of 90% (60/67). There were no false-positives in either group, yielding specificity and positive predictive values (PPVs) of 100%."
      Comparing the Diagnostic Accuracy of Ultrasound and CT in Evaluating Acute Cholecystitis
      Wertz JR et al.
      AJR 2018; 211:W92–W97
    • "However, US is still our first test of choice if AC is suspected clinically, whereas CT is performed when the clinical picture is unclear. US and CT are complementary: If the initial test is negative and there is clinical suspicion of AC or if the ini- tial examination is equivocal, the other examination should be performed. In our practice if both studies are negative for AC and clinical suspicion is high for AC, hepatoiminodiacetic acid scanning is performed.
      Comparing the Diagnostic Accuracy of Ultrasound and CT in Evaluating Acute Cholecystitis
      Wertz JR et al.
      AJR 2018; 211:W92–W97
    • "The sensitivity of US (68%) and CT (85%) for AC were not as good as sensitivities reported in prior studies: 81% for US and 94% for CT. CT at our institution was statistically significantly better for the diagnosis of AC than US, most likely because of an unclear clinical picture, the patient population, and a high proportion of poor-quality US examinations."
      Comparing the Diagnostic Accuracy of Ultrasound and CT in Evaluating Acute Cholecystitis
      Wertz JR et al.
      AJR 2018; 211:W92–W97
GU Misc

    • "RALRP is a minimally invasive surgery for localized prostate cancer, and its use has increased recently. Intraperitoneal extension of vesicourethral anastomotic leak after RALRP can occur, which is not associated with radical retropubic prostatectomy. MDCT cystography is a fast and accurate method for detection and evaluation of the extent of anastomotic leak after RALRP."
      Anastomotic Leak After Robot-Assisted Laparoscopic Radical Prostatectomy: Evaluation With MDCT Cystography With Multiplanar Reformatting and 3D Display
      Satomi Kawamoto et al.
      AJR 2012; 199:W595–W601
    • "RALRP provides several advantages over open and laparoscopic prostatectomy, such as precise dissection through improved instrument control with articulating tips, 3D vision and magnified views, intuitive eye-hand coordination, motion scaling, and filter of tremor."
      Anastomotic Leak After Robot-Assisted Laparoscopic Radical Prostatectomy: Evaluation With MDCT Cystography With Multiplanar Reformatting and 3D Display
      Satomi Kawamoto et al.
      AJR 2012; 199:W595–W601
    • "Robot-assisted laparoscopic radical prostatectomy (RALRP) is a minimally invasive surgery for localized prostate cancer using robotic surgical technology. There has been an evolution of surgical treatment of prostate cancer from open prostatectomy to laparoscopic prostatectomy to RALRP in recent years."
      Anastomotic Leak After Robot-Assisted Laparoscopic Radical Prostatectomy: Evaluation With MDCT Cystography With Multiplanar Reformatting and 3D Display
      Satomi Kawamoto et al.
      AJR 2012; 199:W595–W601
    • "On CT cystography, when a leak is present, the site and extent of the leak is easily assessed. For an extraperitoneal leak, contrast material extending from the vesicourethral anastomosis confines to the extraperitoneal space. When a pelvic fluid collection or hematoma is seen on CT, CT cystography can show the presence or absence of communication of the anastomotic leak to the pelvic fluid collection or hematoma."
      Anastomotic Leak After Robot-Assisted Laparoscopic Radical Prostatectomy: Evaluation With MDCT Cystography With Multiplanar Reformatting and 3D Display
      Satomi Kawamoto et al.
      AJR 2012; 199:W595–W601
    • "Intraperitoneal anastomotic leak from vesi- courethral anastomosis is an uncommon complication after RALRP. In patients with intra- peritoneal leak, unenhanced CT often shows ascites. On CT cystography, contrast material from the anastomotic leak extend- ing into the peritoneal space is easily detected."
      Anastomotic Leak After Robot-Assisted Laparoscopic Radical Prostatectomy: Evaluation With MDCT Cystography With Multiplanar Reformatting and 3D Display
      Satomi Kawamoto et al.
      AJR 2012; 199:W595–W601
    • "The reported incidence of anastomotic leak after open radical prostatectomy is quite variable, ranging from 3.9% to 23% in the prior studies. For laparoscopic radical prostatectomy, anastomotic leak occurred in approximately 10–17% of patients, grossly similar to RALRP."
      Anastomotic Leak After Robot-Assisted Laparoscopic Radical Prostatectomy: Evaluation With MDCT Cystography With Multiplanar Reformatting and 3D Display
      Satomi Kawamoto et al.
      AJR 2012; 199:W595–W601
    • "Anastomotic leak after RALRP is seen in approximately 10% of patients and is mostly limited to the extraperitoneal pelvic space, which is usually transient and requires no fur- ther intervention. Rarely, intraperitoneal leak may occur after RALRP. Most patients with intraperitoneal leak were treated conserva- tively. MDCT cystography is a fast and ac- curate method for detection and evaluation of the extent of anastomotic leak after RALRP."
      Anastomotic Leak After Robot-Assisted Laparoscopic Radical Prostatectomy: Evaluation With MDCT Cystography With Multiplanar Reformatting and 3D Display
      Satomi Kawamoto et al.
      AJR 2012; 199:W595–W601
    • "Primary retroperitoneal masses, which originate in the retroperitoneum but outside the major retroperitoneal organs, are uncommon and can be divided primarily into solid and cystic masses, each of which can be further subdivided into neoplastic and nonneoplastic masses .Of the primary retroperitoneal neoplasms, 70%–80% are malignant in nature, and these account for 0.1%–0.2% of all malignancies in the body."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • Cystic Retroperitoneal Masses
    • "Solid neoplasms in the retroperitoneum can be broadly divided into four groups: (a) mesodermal neoplasms; (b) neurogenic tumors; (c) germ cell, sex cord, and stromal tumors; and (d) lym- phoid and hematologic neoplasms."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Retroperitoneal sarcomas constitute 0.1%–0.2% of all malignancies. Most of the retroperitoneal neoplasms are of mesodermal origin, with
      liposarcomas, leiomyosarcomas, and malignant fibrous histiocytomas making up more than 80% of these tumors. Retroperitoneal sarcomas are commonly seen in the 5th and 6th decades of life. These tumors are large at the time of clinical pre- sentation and often involve adjacent structures. Compression of adjacent organs causes formation of a pseudocapsule.The recurrence rates are high, and metastases to liver, lung, bones, and brain may be seen."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Liposarcoma is the most common (33%) primary retroperitoneal sarcoma. Ten to fifteen percent of liposarcomas occur in the retroperitoneum, and they are more common in the 50–70-year age group, with no sex predilection. Histologically, liposarcoma is classified, in increasing order of malignancy, into four subtypes: well-differentiated, myxoid, pleomorphic, and round cell subtypes. Various histologic subtypes may be seen in the same lesion. Liposarcoma is usually large (average diameter, >20 cm) and is a slow-growing tumor."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "The well-differentiated subtype, the most common type of retroperitoneal liposarcoma, is a predominantly hypoattenuating lesion on CT images because of its fat content."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Leiomyosarcoma is the second most common (28%) primary retroperitoneal sarcoma. Leiomyosarcoma arises from retroperitoneal smooth muscle tissue, blood vessels, or wolf an duct remnants and can grow to a large size (>10 cm) before compromising adjacent organs and precipitating clinical symptoms such as venous thrombosis. Leiomyosarcoma is more common in women, in the 5th to 6th decades of life."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Approximately 6% of leiomyosarcomas arise from the IVC. Most of these tumors have a large extravascular component that makes it difficult to distinguish them from a secondary involvement of the IVC with an extrinsic tumor.The most commonly affected location is the segment between the diaphragm and renal veins."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "At CT, leiomyosarcoma of the IVC is depicted as an intermediate- attenuation mass with heterogeneous enhance- ment. Intraluminal masses result in expansion and obstruction of the IVC, and extraluminal masses cause extrinsic compression and proximal dilation."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Neurogenic tumors constitute 10%–20% of primary retroperitoneal tumors. Compared with the mesenchymal tumors, neurogenic tumors occur in a younger age group and are more likely to be benign and have a better prognosis. Neurogenic tumors can originate from the nerve sheath (schwannoma, neuro broma, neurofibromatosis, malignant nerve sheath tumors), ganglionic cells (ganglioneuroma, ganglioneuroblastoma, neuroblastoma), or paraganglionic cells (paraganglioma, pheochromocytoma)."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Neurogenic tumors are seen commonly (a) along the sympathetic ganglia, which are located in the paraspinal region, and (b) in the adrenal medulla or the organs of Zuckerkandl (paraaortic bodies). Less commonly, neurogenic tumors occur in other sites, such as the urinary bladder, abdominal wall, bowel wall, or gallbladder."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Schwannoma, or neurilemoma, is a benign tumor that arises from the perineural sheath of Schwann (neurilemma). Schwannoma accounts for 6% of retroperitoneal neoplasms and is more common than neurofibroma. Schwannoma is usually asymptomatic and is more common in females (2:1), particularly in the 20–50-year age group."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "At CT, small schwannomas are round, well defined, and homogeneous, but large schwannomas may be heterogeneous in appearance. Calcification can be punctate, mottled, or curvilinear. The nerve of origin is often difficult to identify. After contrast enhancement, schwannoma demonstrates variable homogeneous or heterogeneous enhancement."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Neurofibroma is a benign nerve sheath tumor that can occur as an isolated tumor (90%) or as part of type 1 neuro fibromatosis. Approximately 30% of solitary tumors and 100% of multiple tumors or plexiform neurofibromas are associated with type 1 neurofibromatosis. Neuro- fibroma is more common in men, particularly in the 20–40-year age group."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "At CT, neurofibroma is depicted as a well- defined round homogeneously hypoattenuating lesion (20–25 HU) because of the presence of lipid-rich Schwann cells and adipocytes and en- trapment of adjacent fat. Typically, there is homogeneous contrast enhancement (30–50 HU) that is due to collagen bands, but cystic areas caused by myxoid degeneration may be seen."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Ganglioneuroma is a rare benign tumor that arises from the sympathetic ganglia. It is usually asymptomatic but can manifest with pain or a mass. Ganglioneuroma occasionally secretes hormones such as catecholamines, vasoactive intestinal peptides, or androgenic hormones.This tumor is commonly seen in the 20–40- year age group, with no sex predilection . Histopathologically, ganglioneuroma is composed of Schwann cells, ganglion cells, and nerve fibers."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Teratoma is a germ cell tumor that originates from pluripotent germ cells that have been interrupted in their normal migration to the genital ridges. Less than 10% of teratomas are found in the retroperitoneum. Teratoma accounts for as many as 11% of primary retroperitoneal tumors and is the third most common tumor in the retroperitoneum in children, after neuroblastoma and Wilms tumor."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Teratoma is more common in females, with a bimodal age distribu- tion (<6 months and early adulthood). Teratoma can be benign or malignant, and benign teratoma can be either mature or immature."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Mature teratoma (dermoid cyst) contains well- differentiated tissues from at least two germ cell layers. Ectodermal layers are seen in all, mesodermal layers in 90% of lesions, and endodermal layers in the majority of lesions. Mature teratomas are predominantly cystic. Calcification (toothlike or well defined) and fat can be seen in 56% and 93% of cases, respectively."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "A fat-fluid (sebum) level and chemical shift between fat and fluid are pathognomonic. A villiform solid component known as a Rokitansky protuberance is seen in 81% of cases. Malignancy has been reported in 2%–3% of mature teratomas, more commonly in children (26%) than adults (10%), and is associated with wall thickening, irregular margins, and infiltration of adjacent organs."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Compared with mature teratoma, immature teratoma is less common (<1%), contains more than 10% undifferentiated tissue, and is seen in
      a younger age group (<20 years). The most common location of immature teratoma is near the upper pole of the left kidney. Immature tera- toma is predominantly solid, with scattered areas of fat and calcification (coarse and ill de fined), but cystic components are found occasionally."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
    • "Malignant teratoma can have germ cell or non–germ cell malignant tissue. Malignant trans- formation is less common in the retroperitoneum (38). Malignant tumors are irregular, with inva- sion of adjacent structures and vascular invasion. A poor prognosis is associated with lesions with germ cells or lesions with rhabdomyosarcoma or neural differentiation. An elevated a-fetoprotein level is found in 50% of malignant teratomas. Surgical resection is required for definitive diagnosis and treatment."
      Imaging of Uncommon Retroperitoneal Masses
      Rajiah P et al.
      RadioGraphics 2011; 31:949–976
Kidney

    • Renal Artery Aneurysms: Facts
      • Renal artery aneurysms occur with a frequency of less than 1% of the general population.
      • they can be complicated with life-threatening conditions like rupture, thrombosis, embolism, or hypertension. 
      • RAA accounts for 22% of visceral aneurysms
    • Renal Artery Aneurysms: Facts
      • According to a study enrolling adults without renovascular disease, the normal renal artery diameter is approximately 0.5 cm
      • Regarding patients with hypertension, the frequency of the RAA rises to 2.5% and when the hypertension is unresponsive to medical therapy, it can be as high as 39%
    • In general, there are four types of RAAs: the saccular, fusiform, dissecting, and the arteriovenous/microaneurysm (intrarenal) with the saccular being the most frequent one as it accounts for about 70% of all RAAs. Risk factors for the development of an RAA include renal congenital malformations, untreated hypertension, atherosclerosis, trauma, pregnancy, recent surgery, malignancy, angiomyolipoma of the kidney, radiation exposure, and use of drugs like cyclophosphamide 
    • Renal Artery Aneurysm: Complications
      • RAAs usually cause no symptoms but can be complicated by important conditions;
           • rupture,
           • thrombosis,
           • distal embolism,
           • obstructive uropathy,
           • hypertension of renovascular aetiology
           • arteriovenous communications 
    • "RAA should be always included in the differential diagnosis of parapelvic, pararenal masses with rim-like calcification. Even though they can be asymptomatic and incidentally found, they should always be reported and fully investigated. Furthermore, they should always be followed up and under certain indications treated to avoid life-threatening complications."
      Imaging of a Renal Artery Aneurysm Detected Incidentally on Ultrasonography
      Vasileios Rafailidis
      Case Reports in Radiology
      Volume 2014, Article ID 375805
Liver

    • "Hepatic infarction is defined as areas of coagulation necrosis from hepatocyte cell death caused by local ischemia, which in turn results from the obstruction of circulation to the affected area, most commonly by a thrombus or embolus. Hepatic infarction is uncommon because of the dual blood supply from the hepatic artery and portal vein, as well as extensive collateral vessels. In most cases, hepatic infarction results from either insult to the hepatic artery or portal vein thrombosis superimposed on hepatic arterial occlusion."
      CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders
      Maha Torabi et al.
      RadioGraphics 2008; 28:1967–1982
    • "Hepatic infarction may be iatrogenic (occurring after hepatobiliary surgery, intrahepatic chemoembolization, or a transjugular intrahepatic portosystemic shunt procedure) or posttraumatic (occurring after hepatic artery or portal vein laceration)."
      CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders
      Maha Torabi et al.
      RadioGraphics 2008; 28:1967–1982
    • "It may occur as a complication of hepatic artery stenosis or thrombosis after liver transplantation, or it may be secondary to hypercoagulability (in sickle cell disease or antiphospholipid antibody syndrome), vasculitis (in polyarteritis nodosa or systemic lupus erythematosus), or infection (in sepsis and shock or rare "emphysematous hepatitis")."
      CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders
      Maha Torabi et al.
      RadioGraphics 2008; 28:1967–1982
    • "Hepatic infarction is uncommon, occurring at any age, without sex predilection. Hepatic artery thrombosis leading to infarction most often occurs after hepatic transplantation and has been reported in 3% of adult transplant recipients and 12% of pediatric transplant recipients."
      CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders
      Maha Torabi et al.
      RadioGraphics 2008; 28:1967–1982
    • "Gas formation has been described in sterile infarcts as well as infected ones. Sterile gas is related to the release of intracellular gas from necrotic tissue, an origin similar to that of gas bubbles in hepatic tumors after embolization therapy or radiofrequency ablation."
      CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders
      Maha Torabi et al.
      RadioGraphics 2008; 28:1967–1982
    • "Infarction is a serious complication of liver transplantation that results in significant morbidity and mortality and often requires repeat transplantation. Preservation of portal tracts is a feature worthy of emphasis because it helps differentiate infarction from other causes of hypoattenuating foci in transplanted livers (eg, abscess, biloma, and postbiopsy hematoma)."
      CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders
      Maha Torabi et al.
      RadioGraphics 2008; 28:1967–1982
    • "Focal steatosis may mimic hepatic infarction; however, steatosis tends to occur in characteristic locations, and the enhancement of vessels in focal regions of steatosis is preserved, with enhancement approaching that of normal liver parenchyma. Hepatic abscess, which also is included in the differential diagnosis, often has a cluster-of-grapes appearance with rimlike peripheral enhancement and a nonenhancing central pyogenic component."
      CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders
      Maha Torabi et al.
      RadioGraphics 2008; 28:1967–1982
Musculoskeletal

    • Non-traumatic abnormalities:
      FOREIGN BODIES

      • Detection of retained foreign bodies can be extremely challenging in the chronic setting, without definite antecedent penetrating trauma and nonspecific symptoms of pain and or swelling related to foreign body granuloma.
            • Foreign body may produce a variety of signs and symptoms related to its size, composition, and ballistics.
            • Retained foreign bodies may give rise to cellulitis, abscess, fistulas, and myositis.
      • CT has a sensitivity ranging from 65% (for a foreign body <0.06 mm3) to 100% (for foreign bodies >0.06 mm3)
      • CT also aides in providing precise compartmental anatomy and extent of involvement.

      V. Mester, F. Kuhn.
      Intraocular foreign bodies.
      Ophthalmol Clin North Am, 15 (2002), pp. 235–242
    • Renal Osteodystrophy
      Renal osteodystrophy (ROD) starts early with loss of kidney function (approximately 50% loss of glomerular infiltration rates. Virtually all patients with advanced chronic kidney disease (CKD) have ROD, and an association between histologic changes in bone turnover and vascular calcifications has been described. This association underlines the importance of treatment of ROD. 
    • "The main abnormalities of ROD encompass changes in turnover, mineralization, and bone volume; therefore, effects of treatment modalities should be analyzed with respect to these three abnormalities. Three major therapeutic groups are available for the management of ROD: phosphate binders (P-binders), vitamin D or vitamin D analogues, and calcimimetics."
      Effects of Treatment of Renal Osteodystrophy on Bone Histology
      Hartmut H. Malluche et al.
      Clin J Am Soc Nephrol. 2008 Nov; 3(Suppl 3): S157–S163.
    • "Chronic renal insufficiency, hemodialysis, peritoneal dialysis, renal transplantation and administration of different medications provoke complex biochemical disturbances of the calcium–phosphate metabolism with wide spectrum of bone and soft tissue abnormalities termed renal osteodystrophy. Clinically most important manifestation of renal bone disease includes secondary hyperparathyroidism, osteomalacia/rickets, osteoporosis, adynamic bone disease and soft tissue calcification."
      Imaging of renal osteodystrophy
      V. Jevtic
      European Journal of Radiology , Volume 46 , Issue 2 , 85 - 95
    • "As a complication of long-term hemodialysis and renal transplantation amyloid deposition, destructive spondyloarthropathy, osteonecrosis, and musculoskeletal infections may occur. Due to more sophisticated diagnostic methods and more efficient treatment classical radiographic features of secondary hyperparathyroidism and osteomalacia/rickets are now less frequently seen."
      Imaging of renal osteodystrophy
      V. Jevtic
      European Journal of Radiology , Volume 46 , Issue 2 , 85 - 95
    • Non-traumatic abnormalities:
      METABOLIC DISEASES

      • Gout - Gouty tophi composed of monosodium urate crystals can present as soft-tissue masses with mean attenuation values of approximately 160 H , and metastatic or dystrophic calcification within these tophi are best seen on CT .
           • Dual-energy CT may be used to differentiate uric acid from calcium, allowing gouty urate crystals to be distinguished from dystrophic calcifications.
           • Both radiography and conventional diagnostic CT show increased attenuation in both settings of urate crystals and calcium-containing mineralizations.
           • Dual-energy CT may depict subclinical urate crystal deposition at other asymptomatic sites that have been included in the imaging field, this enables the clinician to treat before irreversible joint damage occurs .
    • Non-traumatic abnormalities:
      METABOLIC DISEASES

       
      • CT is useful for detecting mineralization in:
           • Chondrocalcinosis (associated with many disorders including pseudogout)
           • Periarticular deposits of calcium due to metastatic calcification are commonly seen in chronic renal failure

      Hanlon R, King S.
      Overview of the radiology of connective tissue disorders in children.
      Eur J Radiol. 2000 Feb; 33(2):74-84.
    • Non-traumatic abnormalities:
      AUTOIMMUNE DISEASE

      • Autoimmune disease:
           • Sheetlike patterns of calcification in the skin, subcutaneous tissue, and fascial planes (calcinosis universalis).
           • can be seen in association with autoimmune connective tissue disorders, such as polymyositis or dermatomyositis.

      Hanlon R, King S.
      Overview of the radiology of connective tissue disorders in children.
      Eur J Radiol. 2000 Feb; 33(2):74-84.

      Olsen KM, Chew FS
      Tumoral calcinosis: pearls, polemics, and alternative possibilities.
      Radiographics. 2006 May-Jun; 26(3):871-85.
    • Non-traumatic abnormalities:
      VASCULAR DISORDERS


      • VASCULAR MALFORMATIONS:
           • Low flow:
                • Venous malformations, which are characterized by slow flow and the pooling of blood, show serpigenous vascular components that enhance after contrast administration
           • High-flow vascular malformations
                • Arteriovenous fistulas
                • Arteriovenous malformations
                       • will show large feeding arteries in addition to draining vessels although these can occasionally be seen in large low-flow malformations or non-involuting hemangiomas as well
    • Ameloblastoma arises from the enamel-forming cells of the odontogenic epithelium. The tumor most commonly occurs in the posterior mandible, typically in the third molar region. On radiography, the mixed cystic and solid type of ameloblastoma appears as an expansile, radiolucent, multilocular mass, with internal septations that form a honeycomb or soap bubble appearance on all modalities, which is a classic finding.
    • "Osteosarcoma is a primary malignant bone tumour in which the neoplastic cells produce osteoid or bone. It is a rather uncommon tumour constituting approximately 0.2% of all malignancies.Lesions of the mandible and maxilla constitute 6% to 9% of all osteosarcomas. Although it is comparatively rare, osteosarcoma is still a common primary bone tumour of the jaws."
      Osteosarcoma of the jaws: demographic and CT imaging features
      S Wang, H Shi,* and  Q Yu
      Dentomaxillofac Radiol. 2012 Jan; 41(1): 37–42
    • "The characteristic clinical presentation of osteosarcoma of the jaw is swelling, compared with pain in long bone lesions. In our study, the most common symptoms included swelling with or without numbness and limitation of mouth opening."
      Osteosarcoma of the jaws: demographic and CT imaging features
      S Wang, H Shi,* and  Q Yu
      Dentomaxillofac Radiol. 2012 Jan; 41(1): 37–42
    • "Osteosarcomas appearing as an area of bone permeation without a tumour and new bone formation could not be differentiated from metastatic disease radiographically.Osteosarcoma resembling cementoblastomas might mimic "benign" bone growth, but the hard-tissue component is connected with the root of the involved tooth, which usually shows signs of external resorption, and the sharp border between the tubular dentin of the root and the hard-tissue component forms the hallmark of cementoblastomas."
      Osteosarcoma of the jaws: demographic and CT imaging features
      S Wang, H Shi,* and  Q Yu
      Dentomaxillofac Radiol. 2012 Jan; 41(1): 37–42
OB GYN

    • " In cases where CT is needed, protocols should be optimized for the individual with careful planning, with use of dose reduction techniques that allow adequate imaging without unnecessary radiation exposure. As in all cases, the benefit of an imaging diagnosis needs to be weighed against theoretical risks."
      Invited Commentary
      Levine D
      RadioGraphics 2010; 30:1230-1233
    • " The risk associated with a radiologic examination appears to be rather low compared with the natural risk. However, any added risk, no matter how small, is unacceptable if it does not benefit the patient."
      Radiation Risk: What You Should Know to Tell your Patient
      Verdun FR et al.
      RadioGraphics 2008:28:1807-1816
    • " The risk burden of radiation exposure to the fetus has to be carefully weighed against the benefits of obtaining a critical diagnosis quickly and using a single tailored imaging exam ."
      Imaging in Pregnant Patients: Examination Appropriateness
      Wieseler KM et al.
      RadioGraphics 2010; 30:1215-1233
    • "We aimed to combine previously described pregnancy specific CTPA technique alterations with a dose reduction strategy and a low kVp technique to yield a low dose CTPA protocol specifically tailored to pregnant patients, without a reduction in clinical image quality. The results demonstrate that by using a low kVp CTPA technique tailored to pregnancy, effective doses under 1 mSv are routinely achievable in a pregnant population."
      Low dose computed tomography pulmonary angiography protocol for imaging pregnant patients: Can dose reduction be achieved without reducing image quality?
      Halpenny D et al.
      Clinical Imaging: Volume 44, July–August 2017, Pages 101-105
    • "Pregnancy is a hypercoagulable state, and consequently pregnant patients are at high risk for PE. The diagnosis of PE can be challenging in pregnant patients, as the clinical signs and symptoms of PE can mimic the physiological effects of pregnancy. In the ATS/STR guidelines, CTPA is the recommended when a chest radiograph is abnormal and therefore maintains an important role in the evaluation of PE. While both V/Q scintigraphy and CTPA have high sensitivities and specificities, CTPA is quick to perform and interpret, and provides a higher rate of alternate diagnoses."
      Low dose computed tomography pulmonary angiography protocol for imaging pregnant patients: Can dose reduction be achieved without reducing image quality?
      Halpenny D et al.
      Clinical Imaging: Volume 44, July–August 2017, Pages 101-105
    • "CTPA image quality is potentially impacted by the hemodynamic changes of pregnancy. Increased plasma volume, cardiac output, total vascular resistance, and heart rate can lead to hemodilution of injected intravenous contrast with decreased peak arterial enhancement and shorter contrast material arrival time in the pulmonary arteries. Additionally, the gravid uterus increases IVC pressure and can accentuate transient contrast interruption."
      Low dose computed tomography pulmonary angiography protocol for imaging pregnant patients: Can dose reduction be achieved without reducing image quality?
      Halpenny D et al.
      Clinical Imaging: Volume 44, July–August 2017, Pages 101-105
Pancreas

    • Serous cystadenoma
      • Imaging Findings
           • Polycystic: cysts are <2cm; oligocystic cysts are > 2cm
           • Usually in head, 40% in tail
           • Fibrous enhancing septations
           • Central scar with coarse calcification (30%)
           • Does not communicate with duct. Can obstruct duct when large
           • Atypical findings: giant >10 cm, intratumoral hemorrhage, solid appearance (pNET mimic), unilocular with calcification (pseudocyst or mucinous mimic)
    • Serous cystadenoma
      • Frequently incidental cystic tumors found in woman in the 5th to 7th decades.
      • Tumors >4 cm are more likely to be symptomatic
      • Three morphologic types: polycystic (70%), honeycomb (20%) or oligocystic (10%)
    • Correlation between CT Attenuation and Pathologic Classification
      • The polycystic pattern and cystic and solid pattern fit into the microcystic category and represented the most common CT appearance of serous cystadenomas
      • Most of the solid cystadenomas fit into the honeycomb category, in which the individual cysts were too small to be resolved on CT
      • One of the solid cystadenomas was a rare solid variant of serous cystadenoma, which did not contain any cystic spaces on histopathology
    • Correlation between CT Attenuation and Pathologic Classification
    • CT Attenuation As Compared to Other Cystic Pancreatic Lesions


      • Chalian et al. (2011) reported mean CT attenuation values of unilocular cystic pancreatic lesions during the pancreatic parenchymal phase:
          • Pseudocyst 18.9 HU ± 3.8
          • Mucinous cystic neoplasms 13 HU ± 2.5
          • IPMNs 11.4 HU ± 2.7
Practice Management

    • OBJECTIVE. The objective of this study was to determine whether body fat percentage, measured using a portable handheld bioelectric impedance analysis (BIA) device, and body mass index (BMI, weight in kilograms divided by the square of height in meters) can estimate the amount of intraabdominal and intrapelvic fat and thereby predict the need for oral contrast material before abdominopelvic CT.
      CONCLUSION. Using BIA in addition to BMI accurately predicts amount of intraabdominal and intrapelvic fat. This information may help guide the decision to use oral contrast material in patients presenting for abdominopelvic CT.
      Using Body Mass Index and Bioelectric Impedance Analysis to Assess the Need for Positive Oral Contrast Agents Before Abdominopelvic CT
      Wu Y et al.
      AJR 2018; 211:340–346
Stomach

    • "Though breast cancer is a common cancer it rarely metastasizes to stomach. Lobular carcinoma is the most common histological type which presents with gastric metastases. The most common presentation is linitis plastica."
      Gastric metastases from breast cancer: A report of two cases and review of literature.
      Rachan Shetty KS et al.
      J Cancer Res Ther. 2015 Jul-Sep;11(3):660. 
    • "Linitis plastica can affect the entire digestive system. Its potentially secondary nature necessitates a systematic search for a primary tumor. An appropriate CT protocol is required to detect the specific radiological features of this fibrous cancer. CT can help confirm the diagnosis of linitis plastica, rule out differential diagnoses, and indicate the need for deep biopsies where possible."
      Computed tomography features of gastrointestinal linitis plastica: spectrum of findings in early and delayed phase imaging.
      Burgain C et al.
      Abdom Radiol (NY). 2016 Jul;41(7):1370-7. 
    • "Gastric linitis plastica is a diffuse type of cancer which is characterized by a thickening and rigidity of the stomach wall. It is notorious for its failure to cause early symptoms, and patients with symptoms generally have a more advanced form of the disease."
      Managing Gastric Linitis Plastica
      Keep the scalpel sheathed
      Sadaf Jafferbhoy et al
       Qaboos Univ Med J. 2013 Aug; 13(3): 451–453.
    • "Linitis plastica denotes a diffuse type of carcinoma which accounts for 3–19% of gastric adenocarcinomas. It is characterized by a rigidity of a major portion, or all of the stomach, with the absence of a filling defect or extensive ulceration. Gastric carcinoma is notorious for its failure to cause early symptoms so that patients do not present themselves for diagnosis until late in the course of the disease. Because of the rich lymphatic supply, the cancer rapidly disseminates beyond the reach of surgical resection. Consequently, the patients with symptoms generally have far-advanced malignancy."
      Managing Gastric Linitis Plastica
      Keep the scalpel sheathed
      Sadaf Jafferbhoy et al
       Qaboos Univ Med J. 2013 Aug; 13(3): 451–453.
    • "Dyspepsia was the commonest feature of presentation (55%), followed by dysphagia (33%), vomiting (33%) and weight loss (33%). The infiltration of malignant cells reduces the volume of the stomach and interferes with peristalsis so that the stomach acts as a funnel between the oesophagus and duodenum. As a result, food is easily regurgitated into the oesophagus. This was the commonest presentation in these series."
      Managing Gastric Linitis Plastica
      Keep the scalpel sheathed
      Sadaf Jafferbhoy et al
       Qaboos Univ Med J. 2013 Aug; 13(3): 451–453.
    • "In conclusion, gastric linitis plastica is one of the forms of adenocarcinoma which usually presents at a later stage, where curative treatment is not an option for the majority of cases."
      Managing Gastric Linitis Plastica
      Keep the scalpel sheathed
      Sadaf Jafferbhoy et al
       Qaboos Univ Med J. 2013 Aug; 13(3): 451–453.
Vascular

    • "IV drug use may result in a variety of local arterial complications at the injection site. Inadvertent arterial puncture may result in traumatic arterial dissection and even arterial occlusion with consequent acute limb ischemia. Arterial puncture may also result in formation of a false aneurysm."
      Radiology of Recreational Drug Abuse
      Ian G. Hagan et al.
      RadioGraphics 2007; 27:919 –940
    • "Cardiovascular complications include myocardial infarction, cardiomyopathy, arterial dissection, false and mycotic aneurysms, venous thromboembolic disease, and septic thrombophlebitis. Respiratory complications may involve the upper airways, lung parenchyma, pulmonary vasculature, and pleural space. ."
      Radiology of Recreational Drug Abuse
      Ian G. Hagan et al.
      RadioGraphics 2007; 27:919 –940
    • "Awareness of the imaging features of recreational drug abuse is important for the radiologist because the underlying cause may not be known at presentation and because complications affecting different body systems may coexist. Intravenous drug abuse in particular should be regarded as a multisystem disease with vascular and infective complications affecting many parts of the body, often synchronously."
      Radiology of Recreational Drug Abuse
      Ian G. Hagan et al.
      RadioGraphics 2007; 27:919 –940
    • "IV drug use may result in a variety of local arterial complications at the injection site. Inadvertent arterial puncture may result in traumatic arterial dissection and even arterial occlusion with consequent acute limb ischemia. Arterial puncture may also result in formation of a false aneurysm."
      Radiology of Recreational Drug Abuse
      Ian G. Hagan et al.
      RadioGraphics 2007; 27:919 –940
    • "Not infrequently, the nonsterile nature of injections leads to infection of false aneurysms, resulting in mycotic aneurysm formation . The presence of gas within the aneurysm is a rare but pathognomonic feature of infection and is best seen at CT."
      Radiology of Recreational Drug Abuse
      Ian G. Hagan et al.
      RadioGraphics 2007; 27:919 –940
    • Renal Artery Aneurysms: Facts
      • Renal artery aneurysms occur with a frequency of less than 1% of the general population.
      • they can be complicated with life-threatening conditions like rupture, thrombosis, embolism, or hypertension. 
      • RAA accounts for 22% of visceral aneurysms
    • Renal Artery Aneurysms: Facts
      • According to a study enrolling adults without renovascular disease, the normal renal artery diameter is approximately 0.5 cm
      • Regarding patients with hypertension, the frequency of the RAA rises to 2.5% and when the hypertension is unresponsive to medical therapy, it can be as high as 39%
    • • In general, there are four types of RAAs: the saccular, fusiform, dissecting, and the arteriovenous/microaneurysm (intrarenal) with the saccular being the most frequent one as it accounts for about 70% of all RAAs. Risk factors for the development of an RAA include renal congenital malformations, untreated hypertension, atherosclerosis, trauma, pregnancy, recent surgery, malignancy, angiomyolipoma of the kidney, radiation exposure, and use of drugs like cyclophosphamide 
    • Renal Artery Aneurysm: Complications
      • RAAs usually cause no symptoms but can be complicated by important conditions;
            • rupture,
            • thrombosis,
            • distal embolism,
            • obstructive uropathy,
            • hypertension of renovascular aetiology
            • arteriovenous communications
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