3D and Workflow

• “ After years of rapid growth, CT use in the Medicare population declined by 1.7% in 2010. The proportional decline was even greater in inpatients, hospital outpatient departments, and offices. The only place of service for which growth continued was emergency departments. Without the effect of emergency departments the decline in 2010 would have been 4.7%. This downturn should help alleviate previous concerns about overly rapid CT growth.”
  The Recent Downturn in Utilization of CT: The Start of a New Trend?
  Levin DC et al.
  J Am Coll Radiol 2012;9:795-798
• “ It also remains to be seen whether this development is good or bad for our health care system. It would be good if unnecessary or inappropriate studies were being curtailed. But it would be bad if access were being lost to important technology.”
  The Recent Downturn in Utilization of CT: The Start of a New Trend?
  Levin DC et al.
  J Am Coll Radiol 2012;9:795-798
• “ While mere numeric values might be different, commercially available software platforms produce comparable CAC scoring results, which suggests a vendor-independence of the method; however, none of the analyzed software platforms appears to provide a distinct advantage for risk stratification, as the variability of CAC scores depending on the reconstruction interval persists across platforms.”
  Interplatform Reproducibility of CT Coronary Calcium Scoring Software
  Weininger M et al.
  Radiology 2012;265:70-77
• “ Vendor independent reproducibiity of coronary artery calcium scores is a prerequisite for reliable comparison of results and has direct impact on cardiovascular risk stratification, risk modification, and therapeutic monitoring.”
  Interplatform Reproducibility of CT Coronary Calcium Scoring Software
  Weininger M et al.
  Radiology 2012;265:70-77
• “ Within our population, Spearman rank correlation between the workstations was highest at 60% of the R-R interval, which supports the clinical use of this time point during the cardiac cycle for image reconstruction at CT CAC scoring.”
  Interplatform Reproducibility of CT Coronary Calcium Scoring Software
  Weininger M et al.
  Radiology 2012;265:70-77
• Workstation Platforms Used in Comparison
  - Syngo Calcium Scoring ( Siemens Healthcare)
  - Aquarius (TeraRecon Inc)
  - Vitrea (Vital Images)

Adrenal

• “ Tumors that arise from the chromaffin cells of the adrenal medulla are called pheochromocytomas, and those that arise in an extraadrenal location (10%) are referred to as paragangliomas.”
  Imaging of Uncommon Retroperitoneal Masses
  Rajiah P et al.
  RadioGraphics 2011; 31:949-976
• “ Forty percent of paragangliomas produce high catecholamine levels, which result in symptoms such as headache, palpitations, excessive sweating, and elevated urinary metanephrine or VMA levels.”
  Imaging of Uncommon Retroperitoneal Masses
  Rajiah P et al.
  RadioGraphics 2011; 31:949-976
• “ Lymphangioma is a developmental malformation that is caused by failure of communication of retroperitoneal lymphatic tissue with the main lymphatic vessels. Lymphangioma accounts for 1% of all retroperitoneal neoplasms .It is asymptomatic and is more common in men.”
  Imaging of Uncommon Retroperitoneal Masses
  Rajiah P et al.
  RadioGraphics 2011; 31:949-976
• “ The most common imaging features include a 2-3 cm oval hematoma, irregular hemorrhage obliterating the adrenal gland, periadrenal hemorrhage or fat stranding, and uniform adrenal swelling with increased attenuation.”
  Imaging of traumatic adrenal injury
  To’o KJ, Duddalwar VA
  Emerg Radiol (2012) 19:499-503
• “ Traumatic adrenal injury occurs in 5% of cases of blunt abdominal trauma and most commonly affects the right adrenal gland only. While rare, adrenal injury is an indicator of severe trauma and should prompt a search for associated injuries. The most common imaging feature of adrenal injury is a 2-3cm oval hematoma.”
  Imaging of traumatic adrenal injury
  To’o KJ, Duddalwar VA
  Emerg Radiol (2012) 19:499-503
• Adrenal Trauma: CT Findings
  - Adrenal hematoma (oval or round)
  - Irregular hemorrhage obliterating the gland
  - Uniform adrenal gland swelling with increased attenuation
  - Periadrenal hemorrhage or stranding
  - Retroperitoneal hemorrhage
  - Adrenal pseudocyst (chronic)
  - Imaging of traumatic adrenal injury
  To’o KJ, Duddalwar VA
  Emerg Radiol (2012) 19:499-503
• “ In patients with RCC and HCC who undergo dedicated adrenal CT imaging for known adrenal lesions, the percentage enhancement washout of adrenal metastases is similar to that of lipid-poor adrenal adenomas. Careful imaging follow-up or pathologic tissue confirmation is needed.”
  Evaluation of Adrenal Metastases from Renal Cell Carcinoma and hepatocellular Carcinoma: Use of Delayed Contrast Enhanced CT
  Choi YA et al
  Radiology 2013; 266:514-520
• The key is the attenuation differences of the venous phase images
• “ Pheochromocytomas are often considered the great mimicker of other adrenal tumors. Because of their varied clinical, imaging, and pathologic appearances, accurate diagnosis can be challenging.”
  Pheochromocytoma: The Range of Appearances on Ultrasound, CT, MRI, and Functional Imaging
  Leung K et al.
  AJR 2013; 200:370-378
• Pheochromocytoma: Facts
  90% are sporadic and 10% are part of syndromes
  - von Hippel-Lindau syndrome (10-26%)
  - MEN Type II (50%)
  - Neurofibromatosis Type 1 (1%)
  - Pheochromocytoma-Paraganglioma Syndromes Associated with SDHB and SDHD Mutation
• Pheochromocytoma: CT Findings
  - Calcifications are found in 10% of Pheochromocytomas
  - Pheochromocytomas typically are vascular on early phase CT scans
  - Pheochromocytomas can have a 50% washout value and behave just like an adenoma
  - In the absence of metastases it is hard to diagnosis whether or not a Pheochromocytoma is malignant

Cardiac

• “ While mere numeric values might be different, commercially available software platforms produce comparable CAC scoring results, which suggests a vendor-independence of the method; however, none of the analyzed software platforms appears to provide a distinct advantage for risk stratification, as the variability of CAC scores depending on the reconstruction interval persists across platforms.”
  Interplatform Reproducibility of CT Coronary Calcium Scoring Software
  Weininger M et al.
  Radiology 2012;265:70-77
• “ Vendor independent reproducibiity of coronary artery calcium scores is a prerequisite for reliable comparison of results and has direct impact on cardiovascular risk stratification, risk modification, and therapeutic monitoring.”
  Interplatform Reproducibility of CT Coronary Calcium Scoring Software
  Weininger M et al.
  Radiology 2012;265:70-77
• “ Within our population, Spearman rank correlation between the workstations was highest at 60% of the R-R interval, which supports the clinical use of this time point during the cardiac cycle for image reconstruction at CT CAC scoring.”
  Interplatform Reproducibility of CT Coronary Calcium Scoring Software
  Weininger M et al.
  Radiology 2012;265:70-77
• Workstation Platforms Used in Comparison
  - Syngo Calcium Scoring ( Siemens Healthcare)
  - Aquarius (TeraRecon Inc)
  - Vitrea (Vital Images)
• “ Multidetector computed tomographic (CT) angiography is a promising complementary technique for evaluation of prosthetic heart valves (PHV), especially in patients with PHV obstruction and endocarditis.”
  Multidetector CT Angiography in Evaluation of Prosthetic Heart Valve Dysfunction
  Habets J et al
  RadioGraphics 2012; 32:1893-1905
• “ Retrospectively electrocardiographically gated acquisition is advisable for PHV imaging because it enables dynamic leaflet evaluation and anatomic assessment in both systole and diastole.”
  Multidetector CT Angiography in Evaluation of Prosthetic Heart Valve Dysfunction
  Habets J et al
  RadioGraphics 2012; 32:1893-1905
• Prosthetic Heart Valves: Facts
  - Two main types are biologic and mechanical prosthetic heart valves
  - Biologic prosthetic heart valves require no anticoagulation but are prone to wear and will degenerate within 10-20 years
  - Mechanical prosthetic heart valves require anticoagulation for life but failure is rare and reported as 0.01%-6%
  - CT especially of value in biologic prosthetic heart valves when associated abscess is suspected
• “ A patient centered approach to imaging as a component of patient centered care individualizes the decision to use imaging with ionizing radiation for every patient, avoids unnecessary repeat exposure to ionizing radiation, leads to performance of imaging studies in a manner that minimizes radiation while maintaining image quality sufficient for confident and accurate interpretation.”
  Radiation Dose in Cardiac Imaging: How Should It Affect Clinical Decisions
  Shapiro BP et al.
  AJR 2013; 200:508-514

Chest

• “To conduct a systematic review of the evidence regarding the benefits and harms of lung cancer screening using low-dose computed tomography (LDCT). A multisociety collaborative initiative (involving the American Cancer Society, American College of Chest Physicians, American Society of Clinical Oncology, and National Comprehensive Cancer Network) was undertaken to create the foundation for development of an evidence-based clinical guideline.”
  Benefits and harms of CT screening for lung cancer: a systematic review
  Bach PB et al.
  JAMA 2012 Jun 13;307(22):2418-29
• “Three randomized studies provided evidence on the effect of LDCT screening on lung cancer mortality, of which the National Lung Screening Trial was the most informative, demonstrating that among 53,454 participants enrolled, screening resulted in significantly fewer lung cancer deaths (356 vs 443 deaths; lung cancer?specific mortality, 274 vs 309 events per 100,000 person-years for LDCT and control groups, respectively; relative risk, 0.80; 95% CI, 0.73-0.93; absolute risk reduction, 0.33%; P = .004). The other 2 smaller studies showed no such benefit.”
  Benefits and harms of CT screening for lung cancer: a systematic review
  Bach PB et al.
  JAMA 2012 Jun 13;307(22):2418-29
• “Three randomized studies provided evidence on the effect of LDCT screening on lung cancer mortality, of which the National Lung Screening Trial was the most informative, demonstrating that among 53,454 participants enrolled, screening resulted in significantly fewer lung cancer deaths (356 vs 443 deaths; lung cancer?specific mortality, 274 vs 309 events per 100,000 person-years for LDCT and control groups, respectively; relative risk, 0.80; 95% CI, 0.73-0.93; absolute risk reduction, 0.33%; P = .004). The other 2 smaller studies showed no such benefit.”
  Benefits and harms of CT screening for lung cancer: a systematic review
  Bach PB et al.
  JAMA 2012 Jun 13;307(22):2418-29
• “In terms of potential harms of LDCT screening, across all trials and cohorts, approximately 20% of individuals in each round of screening had positive results requiring some degree of follow-up, while approximately 1% had lung cancer. There was marked heterogeneity in this finding and in the frequency of follow-up investigations, biopsies, and percentage of surgical procedures performed in patients with benign lesions. Major complications in those with benign conditions were rare.”
  Benefits and harms of CT screening for lung cancer: a systematic review
  Bach PB et al.
  JAMA 2012 Jun 13;307(22):2418-29
• “Low-dose computed tomography screening may benefit individuals at an increased risk for lung cancer, but uncertainty exists about the potential harms of screening and the generalizability of results.”
  Benefits and harms of CT screening for lung cancer: a systematic review
  Bach PB et al.
  JAMA 2012 Jun 13;307(22):2418-29
  “ Low-dose CT screening has been as
  sociated with a 20% reduction in lung cancer mortality in a large randomized controlled trial (National Lung Screening Trial [NLST]) of a high-risk population. Mortality data have not yet been reported for 5 other randomized controlled trials, and the sample sizes were too small to detect a meaningful difference in 2 other completed trials. A major risk of CT screening is a high false-positive rate, with associated risks and costs associated with follow-up CT scans and the potential for more invasive diagnostic procedures. Published guidelines for screening indicate a consensus that screening may be indicated for individuals who meet entry criteria for the NLST, but some guidelines expand their recommendations for screening beyond these criteria.”
  Computed tomography screening for lung cancer
  Boiselle PM
  JAMA 2013 Mar 20:309(11):1163-70
• “ A major risk of CT screening is a high false-positive rate, with associated risks and costs associated with follow-up CT scans and the potential for more invasive diagnostic procedures. Published guidelines for screening indicate a consensus that screening may be indicated for individuals who meet entry criteria for the NLST, but some guidelines expand their recommendations for screening beyond these criteria.”
  Computed tomography screening for lung cancer
  Boiselle PM
  JAMA 2013 Mar 20:309(11):1163-70
• “Individuals at high risk of lung cancer who meet the criteria for CT screening in published guidelines should participate in an informed and shared decision-making process by discussing the potential benefits, harms, and uncertainties of screening with their physicians.”
  Computed tomography screening for lung cancer
  Boiselle PM
  JAMA 2013 Mar 20:309(11):1163-70
• 
• Lung cancer is the leading cause of cancer-related mortality in the United States and worldwide. In 2012, it is estimated that 160,300 deaths (87,700 in men, 72,600 in women) from lung cancer will occur in the United States. Five-year survival rates for lung cancer are only 15.9%, partly because most patients have advanced-stage lung cancer at initial diagnosis (http://seer.cancer.gov/statfacts/html/lungb.html). lungb.html).
• “The goal of screening is to detect disease at a stage when it is not causing symptoms and when treatment is most successful. Screening should benefit the individual by increasing life expectancy and increasing quality of life. The rate of false-positive results should be low to prevent unnecessary additional testing. The large fraction of the population without the disease should not be harmed (low risk), and the screening test should not be so expensive that it places an onerous burden on the health care system. Thus, the screening test should: 1) improve outcome; 2) be scientifically validated (e.g., have acceptable levels of sensitivity and specificity); and 3) be low risk, reproducible, accessible, and cost effective.”
  NCCN Guidelines Version 1.2013
• “The goal of screening is to detect disease at a stage when it is not causing symptoms and when treatment is most successful. Screening should benefit the individual by increasing life expectancy and increasing quality of life. The rate of false-positive results should be low to prevent unnecessary additional testing.”
  NCCN Guidelines Version 1.2013
• “The large fraction of the population without the disease should not be harmed (low risk), and the screening test should not be so expensive that it places an onerous burden on the health care system. Thus, the screening test should: 1) improve outcome; 2) be scientifically validated (e.g., have acceptable levels of sensitivity and specificity); and 3) be low risk, reproducible, accessible, and cost effective.”
  NCCN Guidelines Version 1.2013
• “It is recommended that institutions performing lung cancer screening use a multidisciplinary approach that may include specialties such as chest radiology, pulmonary medicine, and thoracic surgery. Management of downstream testing and follow-up of small nodules are imperative and may require the establishment of administrative processes to ensure adequate follow-up. Guidelines from ACCP (American College of Chest Physicians) and ASCO (American Society of Clinical Oncology) state that only centers with considerable expertise in lung cancer screening should do LDCT. ”
  NCCN Guidelines Version 1.2013
• Who should get screening CT scans?
  - Age
  - Sex
  - Length of time patient smoked
  - Amount of smoking (pack years)
  - Family history
  - Clinical symptoms
• NCCN Recommendations
  Age 55 to 74 years; 30 or more pack-year history of smoking tobacco; and, if former smoker, have quit within 15 years (category 1). Some high-risk individuals in the NLST also had COPD and other risk factors. This is a category 1 recommendation because these individuals are selected based on the NLST inclusion criteria. An NCCN category 1 recommendation is based on high-level evidence (i.e., randomized controlled trial) and uniform consensus among panel members. Annual screening is recommended for these high-risk individuals for 2 years (category 1) based on the NLST. Annual screening can be considered until the patient is no longer eligible for definitive treatment. However, uncertainty exists about the appropriate duration of screening and the age at which screening is no longer appropriate.
• NCCN Recommendations
  ·Age 50 years or older, 20 or more pack-year history of smoking tobacco, and one additional risk factor (category 2B). This is a category 2B recommendation because these individuals are selected based on lower level evidence (e.g., nonrandomized studies, observational data, and ongoing randomized trials) and because some panel members would not recommend LDCT for these individuals These additional risk factors were previously described and include cancer history, lung disease history, family history of lung cancer, radon exposure, and occupational exposure. Note that the NCCN Lung Cancer Screening Panel does not currently believe that exposure to second-hand smoke is an independent risk factor, because the data are either weak or variable (see “Exposure to Second-Hand Smoke” in this Discussion).
• The possible or projected risks of screening for lung cancer using LDCT scans include 1) false-positive results, leading to unnecessary testing, unnecessary invasive procedures (including surgery), increased cost, and decreased quality of life because of mental anguish; 2) false-negative results, which may delay or prevent diagnosis and treatment because of a false sense of good health; 3) futile detection of small aggressive tumors (which have already metastasized, preventing meaningful survival benefit from screening); 4) futile detection of indolent disease (i.e., over diagnosis), which would never have harmed the patient who subsequently undergoes unnecessary therapy; 5) indeterminate results, leading to additional testing; 6) radiation exposure; and 7) physical complications from diagnostic workup. Patients with several comorbid conditions may be at greater risk than those with few or none.
• Potential Risk of Lung Cancer Screening
  1) false-positive results, leading to unnecessary testing, unnecessary invasive procedures (including surgery), increased cost, and decreased quality of life because of mental anguish
   2) false-negative results, which may delay or prevent diagnosis and treatment because of a false sense of good health;
  3) futile detection of small aggressive tumors (which have already metastasized, preventing meaningful survival benefit from screening);
  4) futile detection of indolent disease (i.e., overdiagnosis), which would never have harmed the patient who subsequently undergoes unnecessary therapy
   5) indeterminate results, leading to additional testing
   6) radiation exposure;
  7) physical complications from diagnostic workup. Patients with several comorbid conditions may be at greater risk than those with few or none.
• “Lung cancer screening with LDCT is a complex and controversial topic, with inherent risks and benefits. Results from the large, prospective, randomized NLST showed that screening with LDCT decreased the relative risk of death from lung cancer by 20% in a select group of high-risk individuals. The NLST results indicate that to prevent one death from lung cancer, 320 high-risk individuals must be screened with LDCT.”
  NCCN Guidelines Version 1.2013 Lung Cancer Screening 
• 
• 
• 
• 
• 
• 
• “ Unenhanced CT performed well in detection of acute aortic syndrome treated surgically, although its performance does not support its use in place of contrast enhanced CTA. Unenhanced CT may be a reasonable first examination for rapid triage when IV contrast is contraindicated.”
  Acute Aortic Syndromes: A Second Look at Dual-Phase CT
  Lovy AJ et al.
  AJR 2013; 200:805-811
• “ Contrast-enhanced CTA was highly sensitive for intramural hematoma, suggesting that unenhanced imaging may not always be needed. Acute aortic syndrome imaging protocols should be optimized to reduce radiation dose.”
  Acute Aortic Syndromes: A Second Look at Dual-Phase CT
  Lovy AJ et al.
  AJR 2013; 200:805-811
• Acute Aortic Syndrome
  - Aortic dissection
  - Intramural hematoma
  - Penetrating atherosclerotic ulcer
  - Ruptured aortic aneurysm
• “ Intramural blood pools (IBP) are frequently observed at multidetector CT in patients with intramural hematoma (IMH). They may resolve over time or appear during follow-up.These findings are not associated with a poor prognosis, and IBPs should be distinguished from ulcer like projections.”
  Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
  Wu MT et al.
  Radiology 2011;258:705-713
• “ Intramural blood pools (IBP) is an intramural contrast medium filled pool with a tiny intimal orifice and/or a connection with an intercostal or lumbar artery in an IMH; IBP is morphologically distinct from an ulcer like projection (ULP) which has a wiser intimal opening to the lumen.”
  Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
  Wu MT et al.
  Radiology 2011;258:705-713
• “ Most Intramural blood pools (IBP) show complete resorption over time (32 of 56 (57%) or have incomplete resorption (16 of 56 (29%) during a median follow-up of 33.8 months; the presence of IBP was not associated with poor prognosis.”
  Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
  Wu MT et al.
  Radiology 2011;258:705-713

Contrast

• “ The ACR Manual on Contrast Media of the American College of Radiology states that available data are insufficient to permit a specific recommended threshold level, but suggests that a creatinine level of 2.0 mg/dL is a level at which below which contrast medium is safe.”
  Quantitating Contrast Medium-induced Nephropathy: Controlling the Controls
  Newhouse JH, RoyChoudhury
  Radiology 2013; 267:4-8
• “ This study showed that increasing the dose of IV contrast medium can compensate for a reduced radiation dose and visa versa while SNR and CNR are maintained.”
  Seesaw Balancing Radiation Dose and IV Contrast Dose: Evaluation of a new Abdinal CT Protocol for Reducing Age Specific Wrist
  AJR 2013; 200:383-388
• “ The three monomeric agents studied (iopamidol 300, iopromide 300, ioxehol 300) and the one dimeric agent (iodixanol 320) were equivalent in terms of lack of a significant effect on measured GFR when administered to patients with normal GFR.”
  Glomerular Filtration Rate in Evaluation of the Effect of Iodinated Contrast Media on Renal Function
  Becker J et al.
  AJR 2013; 200:822-826
• “ Given the remaining uncertainties about the real incidence of contrast medium-induced nephropathy, how should we practice? It is our recommendation that we be more liberal in our policies in regard to contrast medium administration.”
  Quantitating Contrast Medium-induced Nephropathy: Controlling the Controls
  Newhouse JH, RoyChoudhury
  Radiology 2013; 267:4-8

Dual Energy

• “ Dual-energy bone subtraction has been shown to be faster and technically superior to threshold-based bone subtraction techniques even when the latter are manually corrected. However, even dual-energy bone subtraction is not infrequently incomplete.”
  Dual-Energy CT: Vascular Applications
  Vlahos I et al.
  AJR 2012; 199:S87-S97
• “ Although heavily calcified plaque in contact with bone can also be misclassified as bone and removed with dual energy subtraction , DECT’s reliance on iodine-calcium material differentiation reduces the incidence and severity of these artifacts .”
  Dual-Energy CT: Vascular Applications
  Vlahos I et al.
  AJR 2012; 199:S87-S97
• “ The clinical interpretation advantage of 3D-rendered volumetric data are limited by the need for software assisted Hounsfield unit-threshold-based bone subtraction. This is not only time consuming, but the quality of bone subtraction is subject to patient and user dependent variation.”
  Dual-Energy CT: Vascular Applications
  Vlahos I et al.
  AJR 2012; 199:S87-S97
• “Dual energy vascular imaging is a versatile tool for the evaluation of the aorta, craniocervical, and lower limb vasculature. Appropriate use of techniques can save radiation dose, decrease interpretation time, or improve diagnostic accuracy.”
  Dual-Energy CT: Vascular Applications
  Vlahos I et al.
  AJR 2012; 199:S87-S97

 

• “ Dual energy CT (DECT) is an innovative imaging technique that operates on the basic principle of application of two distinct energy settings that make the transition from CT attenuation based imaging to material specific or spectral imaging.”
  Dual-Energy CT: Oncologic Applications
  De Cecco CN et al.
  AJR 2012; 199:S98-S105
• “ DECT is an innovative imaging technique that can have a considerable effect on the care of oncologic patients. The possibility of obtaining different material specific datasets in the same acquisition can improve lesion detection and characterization. This approach can also aid in evaluation of response to therapy, and detection of oncology related disorders.”
  Dual-Energy CT: Oncologic Applications
  De Cecco CN et al.
  AJR 2012; 199:S98-S105

GU Misc

• “ The radiologist should be familiar with the wider range of foreign objects that may be encountered at abdominopelvic CT, be able to recognize them properly, and understand their implications for patient treatment.”
  Foreign Objects Encountered in the Abdominal Cavity at CT
  Gayer G et al
  RadioGraphics 2011; 31:409-428
• “The exact prevalence of foreign body retention is estimated to be one on 1000-1500 intraabdominal surgeries. A large series by Gawande et al. revealed that the abdomen and pelvis are the most common locations for a retained foreign body.”
  Foreign Objects Encountered in the Abdominal Cavity at CT
  Gayer G et al
  RadioGraphics 2011; 31:409-428
• “ A large series by Gawande et al. revealed that the abdomen and pelvis are the most common locations for a retained foreign body. Sixty nine percent of cases involved sponges, whereas 31% involved instruments, with clamps being the most frequently retained instrument.”
  Foreign Objects Encountered in the Abdominal Cavity at CT
  Gayer G et al
  RadioGraphics 2011; 31:409-428
• “ The possibility of a retained foreign body should be considered when unfamiliar findings cannot be explained in any other way. Three dimensional CT offers additional planes that may facilitate the identification and localization of a retained foreign body, particularly in difficult and perplexing cases in which the diagnosis may not be readily apparent on axial CT scans.”
  Foreign Objects Encountered in the Abdominal Cavity at CT
  Gayer G et al
  RadioGraphics 2011; 31:409-428

Kidney

• Purpose: “ To determine whether ureteral segments not filled with contrast material at computed tomographic (CT) urography ever contain tumor detectable only by filling these segments with contrast material”
  
  Conclusion: “ Targeted delayed scanning at CT urography yielded no additional ureteral tumors and resulted in additional radiation exposure.”
  Targeted Delayed Scanning at CT Urography: A Worthwhile Use of Radiation?
  Hack K et al.
  Radiology 2012; 265:143-150
• “ In patients undergoing CT urography for detection of neoplasms, routine additional excretory phase imaging to attempt complete ureteral opacification is not advised, given the low likelihood that the sole manifestation of a tumor will be a filling defect in an otherwise normal ureter.”
  Targeted Delayed Scanning at CT Urography: A Worthwhile Use of Radiation?
  Hack K et al.
  Radiology 2012; 265:143-150
• “ Given the added radiation associated with performing additional delayed scanning, we recommend obtaining only a single additional delayed scan for ureteral nonopacification.”
  Targeted Delayed Scanning at CT Urography: A Worthwhile Use of Radiation?
  Hack K et al.
  Radiology 2012; 265:143-150
• “ Segmental enhancement inversion was not a common or characteristic CT finding for renal oncocytoma and was not helpful in differentiating small renal oncocytomas from RCC.”
  Small Renal Oncocytomas: Is Segmental Enhancement Inversion a Characteristic Finding at Biphasic MDCT?
  O’Malley ME et al.
  AJR 2012; 199:1312-1315
• Segmental Enhancement Inversion : Definition
  - “when a renal mass can be subdivided into two distinct segments showing different degrees of enhancement during the corticomedullary phase, with the relatively highly enhanced segment becoming less enhanced during the nephrographic phase and the less enhanced segment during the corticomedullary phase become more enhanced during the nephrographic phase.”
  - Segmental enhancement inversion at biphasic multidetector   CT: characteristic finding of small renal oncocytoma
  - Kim JI et al
  - Radiology 2009;252:441-448
• “ With a three-phase CT urologic protocol, significant dose reduction in the unenhanced and excretory phases can be achieved when these phases are combined with a normal-dose corticomedullary phase.”
  How Much Dose Can Be Saved in Three Phase CT Urography? A Combination of Normal-Dose Corticomedullary Phase With Low Dose Unenhanced and Excretory Phases
  Dahlman P et al.
  AJR 2012; 199:852-860
• “ It is possible to reduce the total radiation dose for CT urography by 42% by selectively reducing the dose in the unenhanced and excretory phases and systematically evaluating the images obtained in these phases alongside those obtained in the normal dose corticomedullary phase.”
  How Much Dose Can Be Saved in Three Phase CT Urography? A Combination of Normal-Dose Corticomedullary Phase With Low Dose Unenhanced and Excretory Phases
  Dahlman P et al.
  AJR 2012; 199:852-860

Neuroradiology

• “ Most of the interpreted head CT cases read by board certified general radiologist for patients presenting with stroke or stroke symptoms did not result in discordant interpretations as verified by subspecialty experts. Discordant interpretations did not result in changes in clinical management in most cases.”
  Quality Outcomes of Reinterpretation of Brain CT Studies by Subspecialty Experts in Stroke Imaging
  Jordan YJ et al.
  AJR 2012;199:1365-1370
• “ Most of the interpreted head CT cases read by board certified general radiologist for patients presenting with stroke or stroke symptoms did not result in discordant interpretations as verified by subspecialty experts. Discordant interpretations did not result in changes in clinical management in most cases. Double reading of head CT scans for these patients by subspecialty experts appears to be an inefficient method of substantially improving imaging health quality outcomes in stroke.”
  Quality Outcomes of Reinterpretation of Brain CT Studies by Subspecialty Experts in Stroke Imaging
  Jordan YJ et al.
  AJR 2012;199:1365-1370
• “ Double reading of head CT scans for these patients by subspecialty experts appears to be an inefficient method of substantially improving imaging health quality outcomes in stroke.”
  Quality Outcomes of Reinterpretation of Brain CT Studies by Subspecialty Experts in Stroke Imaging
  Jordan YJ et al.
  AJR 2012;199:1365-1370

Pancreas

• “ The most common pancreatic abnormality found on imaging studies is fatty replacement of the pancreas, but calcifications and cysts may also be found. True epithelium lined cysts probably develop as a result of inspissated mucin that obstructs pancreatic ducts.”
  Cystic Lesions of the Pancreas
  Demos TC et al.
  AJR 179, December 2002;1375-1388
• “ Cysts can be single or multiple. Most are microscopic, but infrequently cysts up to several centimeters in diameter are shown on imaging studies. Rarely cysts are so numerous and large that most of the pancreas is replaced. This phenomenon has been termed “Cytosis” and should not be mistaken for a cystic neoplasm.”
  Cystic Lesions of the Pancreas
  Demos TC et al.
  AJR 179, December 2002;1375-1388
• Cystic Fibrosis: CT Findings
  - Complete replacement of the pancreatic gland by fibrofatty tissue
  - Enlargement of the pancreas corresponding to lipomatous pseudohypertrophy
  - Atrophy of the pancreas without fatty replacement
  - Cystic transformation of the pancreatic gland
  - Solitary pancreatic cysts of various sizes
• “ The imaging findings of pancreatic macrocysts seen in our patients are similar to those of uncomplicated pancreatic cysts from any other cause. None of our patients suffered abdominal manifestations attributable to pancreatic cysts.”
  Pancreatic Cytosis in Children and Young Adults with Cystic Fibrosis: Sonographic, CT, and MRI Findings
  Berrocal T et al.
  AJR 2005; 184:1305-1309
• “ These data suggest that serotonin produced by pancreatic endocrine neoplasms may be associated with local fibrosis and stenosis of the pancreatic duct. Clinicians should be aware that small pancreatic endocrine neoplasms can produce pancreatic duct stenosis resulting in ductal dilatation and/or upstream pancreatic atrophy out of proportion to the size of the tumor.”
  Pancreatic Duct Stenosis Secondary to Small Endocrine Neoplasms: A Manifestation of Serotonin Production?
  Shi C et al.
  Radiology 2010; 257:107-114
• “ Clinicians should be aware that small pancreatic endocrine neoplasms can produce upstream ductal dilatation and/or pancreatic atrophy out of proportion to the size of the tumor.”
  Pancreatic Duct Stenosis Secondary to Small Endocrine Neoplasms: A Manifestation of Serotonin Production?
  Shi C et al.
  Radiology 2010; 257:107-114
• “ In rare instances, IgG4-related sclerosing disease manifests atypical features in various organs in the abdomen. It is important that radiologists be aware of the typical and atypical features of this disease to provide timely effective treatment.”
  Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
  Kim JH et al.
  AJR 2013; 200:102-112
• “ IgG4 related sclerosing disease is a systemic disease characterized by extensive infiltration of IgG4-positive plasma cells and lymphocytes in various organs; it responds well to steroid therapy.”
  Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
  Kim JH et al.
  AJR 2013; 200:102-112
• “ The organ most commonly involved in IgG4 related sclerosing disease is the pancreas, and such involvement is termed autoimmune pancreatitis. Various extrapancreatic organs, including the bile ducts, liver, gallbladder, kidneys, retroperitoneum, gastrointestinal tract, mesentery, prostate, lungs, lacrimal and salivary glands, and lymph nodes, can be involved with AIP either synchronously or metachronously, and in rare cases there can be extrapancreatic involvement without any sign of AIP.”
  Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
  Kim JH et al.
  AJR 2013; 200:102-112
• “Various extrapancreatic organs, including the bile ducts, liver, gallbladder, kidneys, retroperitoneum, gastrointestinal tract, mesentery, prostate, lungs, lacrimal and salivary glands, and lymph nodes, can be involved with AIP either synchronously or metachronously, and in rare cases there can be extrapancreatic involvement without any sign of AIP.”
  Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
  Kim JH et al.
  AJR 2013; 200:102-112
• Autoimmune Pancreatitis: Facts
  - Diffuse sausagelike swelling of the pancreas with loss of pancreatic clefts
  - Symmetric capsule like rim of low attenuation surrounding the pancreas
  - Multifocal irregular narrowing of the main pancreatic duct without downstream narrowing
  - Associated renal involvement and retroperitoneal fibrosis is common
• “Focal involvement of the pancreas, focal autoimmune pancreatitis (AIP), has been reported to have an incidence that ranges from 28% to 41%. The image findings of focal AIP can mimic those of pancreatic cancer.”
  Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
  Kim JH et al.
  AJR 2013; 200:102-112
• IgG4-Related Sclerosing Disease: Rare Extrapancreatic  Findings
  - Renal lesions (range from well defined nodules as well as patchy enhancement)
  - Retroperitoneal fibrosis
  - Pseudocysts in the spleen
  - Hepatic focal mass
  - Gastric focal mass
  - Omental infiltration
  - Sclerosing mesenteritis
  - Vas deferens mass
• “ Congenital anomalies and normal variants of the pancreas can present a diagnostic challenge when encountered. Knowledge of pancreatic embryology and of normal anatomic variants is essential to identify these entities and help differentiate them from pathologic conditions, thus preventing potential unnecessary imaging investigation or more invasive procedures such as biopsy of surgery.”
  Anomalies, Anatomic Variants, and Sources of Diagnostic Pitfalls in Pancreatic Imaging
  Borghei P et al.
  Radiology 2013,266:28-36
• Congenital Anomalies of the Pancreas
  - Pancreas divisum
  - Annular pancreas
  - Variation in pancreatic duct course
  - Agenesis and hypoplasia of the pancreas
  - Ectopic pancreas
  - Pancreatic cysts
• Normal Variants and Pitfalls of the Pancreas
  - Fatty infiltration
  - Pseudomass
  
  - Anomalies, Anatomic Variants, and Sources of Diagnostic Pitfalls in Pancreatic Imaging
  Borghei P et al.
  Radiology 2013,266:28-36
• Normal Variants and Pitfalls of the Pancreas
  1. Fatty infiltration
  2. Pseudomass
  - Lobulations of the pancreatic head
  - Nodes near the pancreas simulate a pancreatic mass
  - Splenules simulating a tail of pancreas mass
  - Focal autoimmune pancreatitis
• Annular Pancreas: Facts
  - Segment of pancreas surrounds the second portion of the duodenum
  - Annular pancreas can be confused with a pancreatic mass
  - Two types: extramural and intramural
  - Extramural presents with duodenal obstruction while intramural presents with duodenal ulcerations

Radiation Dose

• “ This study showed that increasing the dose of IV contrast medium can compensate for a reduced radiation dose and visa versa while SNR and CNR are maintained.”
  Seesaw Balancing Radiation Dose and IV Contrast Dose: Evaluation of a new Abdinal CT Protocol for Reducing Age Specific Wrist
  AJR 2013; 200:383-388
• “ With a three-phase CT urologic protocol, significant dose reduction in the unenhanced and excretory phases can be achieved when these phases are combined with a normal-dose corticomedullary phase.”
  How Much Dose Can Be Saved in Three Phase CT Urography? A Combination of Normal-Dose Corticomedullary Phase With Low Dose Unenhanced and Excretory Phases
  Dahlman P et al.
  AJR 2012; 199:852-860
• “ It is possible to reduce the total radiation dose for CT urography by 42% by selectively reducing the dose in the unenhanced and excretory phases and systematically evaluating the images obtained in these phases alongside those obtained in the normal dose corticomedullary phase.”
  How Much Dose Can Be Saved in Three Phase CT Urography? A Combination of Normal-Dose Corticomedullary Phase With Low Dose Unenhanced and Excretory Phases
  Dahlman P et al.
  AJR 2012; 199:852-860

Small Bowel

• Mesenteric Vein Thrombosis: Facts
  - Accounts for 5-15% of all mesenteric ischemic events and is classified as either primary or secondary
  - Primary MVT is idiopathic, whereas secondary MVT can result from a variety of underlying diseases and risk factors including primary hypercoagability states, myeloproliferative neoplasms, pancreatic cancer, recent surgery, and portal hypertension
  - Clinical symptoms of MVT are usually nonspecific and include abdominal pain
• “ Venous causes of acute mesenteric ischemia are less common (5-15% of cases) and are most often the result of a thrombosis of the superior mesenteric vein.”
  Multidetector CT Features of Mesenteric Vein Thrombosis
  Duran R et al.
  RadioGraphics 2012; 32:1503-1522
• Meckel’s Diverticulum: Facts
  - Most common congenital abnormality of the GI tract
  - Occurs in approximately 2% of the population
  - Most patients are asymptomatic while others may have Meckels diverticulitis or GI bleed or even intussusception
• Meckel’s Diverticulum: Facts
  - The diverticulum generally occurs 40-100 cm of the ileocecal valve
  - 90% of Meckel’s Diverticulum are 1-10 cm in size
  - Approximately 50% of Meckel’s Diverticula harbor heterotopic mucosa, more than 60% of which is gastric type
  - Total lifetime complication rate is 4%
• Meckel’s Diverticulum: Complications
  - GI bleeding (usually in pediatric patients)
  - Small bowel obstruction
  - Diverticulitis
  - May be difficult to distinguish from processes like acute appendicitis, inflammatory bowel disease (IBD), other causes of small bowel obstruction (SBO)
• “In conclusion, Meckel’s diverticulitis should be considered in the differential diagnosis of acute abdominal pain in both pediatric and adult patients. If an inflammatory process is visualized on CT in the lower abdomen or pelvis, particularly at midline, or if there is evidence of distal small bowel obstruction, one should carefully search for the presence of an inflamed diverticulum.”
  CT of Meckel’s Diverticulitis in 11 Patients
  Bennett GL, Birnbaum BA, Balthazar EJ
  AJR 2004; 182:625-629
• “In conclusion, Meckel’s diverticulitis should be considered in the differential diagnosis of acute abdominal pain in both pediatric and adult patients.”
  CT of Meckel’s Diverticulitis in 11 Patients
  Bennett GL, Birnbaum BA, Balthazar EJ
  AJR 2004; 182:625-629

Spleen

• “ In addition to conventional morphologic MR imaging, DW (diffusion weighted) imaging can be used as a tool for differentiating intrapancreatic accessory spleen (IPAS) from solid pancreatic tumors.”
  Differentiation of an Intrapancreatic Accessory Spleen from a Small (<3-cm) Solid Pancreatic Tumor: Value of Diffusion-weighted MR Imaging
  Jang KM et al
  Radiology 2013; 268:159-167
• “The diagnosis and differentiation of intrapancreatic accessory spleen from a solid pancreatic tumor by using visual assessment of similarity between pancreatic lesions and spleen on diffusion weighted images yields high diagnostic accuracy (90-95%), sensitivity (95-100%), specificity (86-91%), positive predictive value (86-91%) and negative predictive value (95-100%).”
  Differentiation of an Intrapancreatic Accessory Spleen from a Small (<3-cm) Solid Pancreatic Tumor: Value of Diffusion-weighted MR Imaging
  Jang KM et al
  Radiology 2013; 268:159-167

Trauma

• “ The most common imaging features include a 2-3 cm oval hematoma, irregular hemorrhage obliterating the adrenal gland, periadrenal hemorrhage or fat stranding, and uniform adrenal swelling with increased attenuation.”
  Imaging of traumatic adrenal injury
  To’o KJ, Duddalwar VA
  Emerg Radiol (2012) 19:499-503
• “ Traumatic adrenal injury occurs in 5% of cases of blunt abdominal trauma and most commonly affects the right adrenal gland only. While rare, adrenal injury is an indicator of severe trauma and should prompt a search for associated injuries. The most common imaging feature of adrenal injury is a 2-3cm oval hematoma.”
  Imaging of traumatic adrenal injury
  To’o KJ, Duddalwar VA
  Emerg Radiol (2012) 19:499-503
• Adrenal Trauma: CT Findings
  - Adrenal hematoma (oval or round)
  - Irregular hemorrhage obliterating the gland
  - Uniform adrenal gland swelling with increased attenuation
  - Periadrenal hemorrhage or stranding
  - Retroperitoneal hemorrhage
  - Adrenal pseudocyst (chronic)
  - Imaging of traumatic adrenal injury
  To’o KJ, Duddalwar VA
  Emerg Radiol (2012) 19:499-503
• “ In fact, the injured pancreas may appear normal on CT images, particularly in the first 12 hours after a trauma injury. If the admission CT image shows a normal pancreas but the patient subsequently develops abdominal pain, a repeat CT study obtained 24-48 hours later may show an injury not evident initially.”
  Multidetector CT of Blunt Abdominal Trauma
  Soto JA, Anderson SW
  Radiology 2012; 265:678-693
• Pancreatic Trauma: Facts
  - Neck and body are the most common sites of injury
  - Pancreatic injuries can be classified as contusion, laceration or transection
  - Injury to the pancreatic duct is associated with most severe injuries

Vascular

• “ DECT is an innovative imaging technique that can have a considerable effect on the care of oncologic patients. The possibility of obtaining different material specific datasets in the same acquisition can improve lesion detection and characterization. This approach can also aid in evaluation of response to therapy, and detection of oncology related disorders.”
  Dual-Energy CT: Oncologic Applications
  De Cecco CN et al.
  AJR 2012; 199:S98-S105
• “ Dual-energy bone subtraction has been shown to be faster and technically superior to threshold-based bone subtraction techniques even when the latter are manually corrected. However, even dual-energy bone subtraction is not infrequently incomplete.”
  Dual-Energy CT: Vascular Applications
  Vlahos I et al.
  AJR 2012; 199:S87-S97
• “ Although heavily calcified plaque in contact with bone can also be misclassified as bone and removed with dual energy subtraction , DECT’s reliance on iodine-calcium material differentiation reduces the incidence and severity of these artifacts .”
  Dual-Energy CT: Vascular Applications
  Vlahos I et al.
  AJR 2012; 199:S87-S97
• “ The clinical interpretation advantage of 3D-rendered volumetric data are limited by the need for software assisted Hounsfield unit-threshold-based bone subtraction. This is not only time consuming, but the quality of bone subtraction is subject to patient and user dependent variation.”
  Dual-Energy CT: Vascular Applications
  Vlahos I et al.
  AJR 2012; 199:S87-S97
• “Dual energy vascular imaging is a versatile tool for the evaluation of the aorta, craniocervical, and lower limb vasculature. Appropriate use of techniques can save radiation dose, decrease interpretation time, or improve diagnostic accuracy.”
  Dual-Energy CT: Vascular Applications
  Vlahos I et al.
  AJR 2012; 199:S87-S97
• “ Multidetector computed tomographic (CT) angiography is a promising complementary technique for evaluation of prosthetic heart valves (PHV), especially in patients with PHV obstruction and endocarditis.”
  Multidetector CT Angiography in Evaluation of Prosthetic Heart Valve Dysfunction
  Habets J et al
  RadioGraphics 2012; 32:1893-1905
• “ Retrospectively electrocardiographically gated acquisition is advisable for PHV imaging because it enables dynamic leaflet evaluation and anatomic assessment in both systole and diastole.”
  Multidetector CT Angiography in Evaluation of Prosthetic Heart Valve Dysfunction
  Habets J et al
  RadioGraphics 2012; 32:1893-1905
• Prosthetic Heart Valves: Facts
  - Two main types are biologic and mechanical prosthetic heart valves
  - Biologic prosthetic heart valves require no anticoagulation but are prone to wear and will degenerate within 10-20 years
  - Mechanical prosthetic heart valves require anticoagulation for life but failure is rare and reported as 0.01%-6%
  - CT especially of value in biologic prosthetic heart valves when associated abscess is suspected
• “ Unenhanced CT performed well in detection of acute aortic syndrome treated surgically, although its performance does not support its use in place of contrast enhanced CTA. Unenhanced CT may be a reasonable first examination for rapid triage when IV contrast is contraindicated.”
  Acute Aortic Syndromes: A Second Look at Dual-Phase CT
  Lovy AJ et al.
  AJR 2013; 200:805-811
• “ Contrast-enhanced CTA was highly sensitive for intramural hematoma, suggesting that unenhanced imaging may not always be needed. Acute aortic syndrome imaging protocols should be optimized to reduce radiation dose.”
  Acute Aortic Syndromes: A Second Look at Dual-Phase CT
  Lovy AJ et al.
  AJR 2013; 200:805-811
• Acute Aortic Syndrome
  - Aortic dissection
  - Intramural hematoma
  - Penetrating atherosclerotic ulcer
  - Ruptured aortic aneurysm
• “ Intramural blood pools (IBP) are frequently observed at multidetector CT in patients with intramural hematoma (IMH). They may resolve over time or appear during follow-up. These findings are not associated with a poor prognosis, and IBPs should be distinguished from ulcer like projections.”
  Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
  Wu MT et al.
  Radiology 2011;258:705-713
• “ Intramural blood pools (IBP) is an intramural contrast medium filled pool with a tiny intimal orifice and/or a connection with an intercostal or lumbar artery in an IMH; IBP is morphologically distinct from an ulcer like projection (ULP) which has a wiser intimal opening to the lumen.”
  Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
  Wu MT et al.
  Radiology 2011;258:705-713
• “ Most Intramural blood pools (IBP) show complete resorption over time (32 of 56 (57%) or have incomplete resorption (16 of 56 (29%) during a median follow-up of 33.8 months; the presence of IBP was not associated with poor prognosis.”
  Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course
  Wu MT et al.
  Radiology 2011;258:705-713