Alec J. Megibow

A Pattern Approach to the Abnormal Small Bowel: Observations at MDCT and CT Enterography

OBJECTIVE Imaging of the vast array of pathologic processes occurring in the small bowel has been facilitated by recent advances, including the use of MDCT scanners that acquire isotropic data and neutral oral contrast agents that improve small-bowel distention. CONCLUSION This review shows how a systematic pattern approach can be used to narrow the differential diagnosis when an abnormal small-bowel loop is detected on MDCT.

Pancreatic ductal adenocarcinoma radiology reporting template: Consensus statement of the society of abdominal radiology and the american pancreatic association

Pancreatic ductal adenocarcinoma is an aggressive malignancy with a high mortality rate. Proper determination of the extent of disease on imaging studies at the time of staging is one of the most important steps in optimal patient management. Given the variability in expertise and definition of disease extent among different practitioners as well as frequent lack of complete reporting of pertinent imaging findings at radiologic examinations, adoption of a standardized template for radiology reporting, using universally accepted and agreed on terminology for solid pancreatic neoplasms, is needed. A consensus statement describing a standardized reporting template authored by a multi-institutional group of experts in pancreatic ductal adenocarcinoma that included radiologists, gastroenterologists, and hepatopancreatobiliary surgeons was developed under the joint sponsorship of the Society of Abdominal Radiologists and the American Pancreatic Association. Adoption of this standardized imaging reporting template should improve the decision-making process for the management of patients with pancreatic ductal adenocarcinoma by providing a complete, pertinent, and accurate reporting of disease staging to optimize treatment recommendations that can be offered to the patient. Standardization can also help to facilitate research and clinical trial design by using appropriate and consistent staging by means of resectability status, thus allowing for comparison of results among different institutions.

Dual-source dual-energy MDCT of pancreatic adenocarcinoma: initial observations with data generated at 80 kVp and at simulated weighted-average 120 kVp.

OBJECTIVE The purpose of this study was to determine whether the conspicuity of malignant tumors of the pancreas at dual-source dual-energy CT is better with 80-kVp acquisition than with 120-kVp acquisition simulated with a weighted average. MATERIALS AND METHODS Fifteen patients with pancreatic adenocarcinoma underwent contrast-enhanced dual-source dual-energy CT. The abdominal diameter of all patients was 35 cm or less. Data were reconstructed as a weighted average of the 140- and 80-kVp acquisitions, simulating 120 kVp, and as a pure 80-kVp data set. A region-of-interest cursor was placed within the tumor and the adjacent normal parenchyma, and attenuation differences and contrast-to-noise ratios were calculated for pancreatic tumors at 80 kVp and with the weighted-average acquisition. The 80-kVp and weighted-average images were subjectively compared in terms of lesion conspicuity, image quality, and duct visualization. An exact Wilcoxons matched pairs signed rank test was used to test whether differences in attenuation, contrast-to-noise ratio, and subjective assessment were greater at 80 kVp. RESULTS The mean difference in attenuation for each pancreatic tumor and adjacent portion of normal pancreas was 83.27+/-29.56 (SD) HU at 80 kVp and 49.40+/-23.00 HU at weighted-average 120 kVp. Adenocarcinoma attenuation differences were significantly greater at 80 kVp than at 120 kVp (p=0.00006). Contrast-to-noise ratio was significantly higher at 80 kVp than at 120 kVp (p=0.00147). Subjective analysis showed lesion conspicuity (p=0.001) and duct visualization (p=0.0156) were significantly better on the 80-kVp images. CONCLUSION At portal venous phase dual-source dual-energy CT, the conspicuity of malignant tumors of the pancreas is greater at 80 kVp than with weighted-average acquisition.

Iodine quantification with dual-energy CT: phantom study and preliminary experience with renal masses.

OBJECTIVE The purpose of this study was to validate the utility of dual-source dual-energy MDCT in quantifying iodine concentration in a phantom and in renal masses. MATERIALS AND METHODS A series of tubes containing solutions of varying iodine concentration were imaged with dual-source dual-energy MDCT. Iodine concentration was calculated and compared with known iodine concentration. Single-phase contrast-enhanced dual-source dual-energy MDCT data on 15 patients with renal lesions then were assessed independently by two readers. Dual-energy postprocessing was used to generate iodine-only images. Regions of interest were placed on the iodine image over the lesion and, as a reference, over the aorta, for recording of iodine concentration in the lesion and in the aorta. Another radiologist determined lesion enhancement by comparing truly unenhanced with contrast-enhanced images. Mixed-model analysis of variance based on ranks was used to compare lesion types (simple cyst, hemorrhagic cyst, enhancing mass) in terms of lesion iodine concentration and lesion-to-aorta iodine ratio. RESULTS In the phantom study, there was excellent correlation between calculated and true iodine concentration (R(2) = 0.998, p < 0.0001). In the patient study, 13 nonenhancing (10 simple and three hyperdense cysts) and eight enhancing renal masses were evaluated in 15 patients. The lesion iodine concentration and lesion-to-aorta iodine ratio in enhancing masses were significantly higher than in hyperdense and simple cysts (p < 0.0001). CONCLUSION Iodine quantification with dual-source dual-energy MDCT is accurate in a phantom and can be used to determine the presence and concentration of iodine in a renal lesion. Characterization of renal masses may be possible with a single dual-source dual-energy MDCT acquisition without unenhanced images or reliance on a change in attenuation measurements.

Metastatic disease to the pancreas: evaluation by computed tomography.

Seven patients with one or more pancreatic masses due to metastases to the pancreatic parenchyma were studied by CT. Two patterns were observed. Three patients had multiple nodules studding the pancreatic surface. Four patients had a solitary focal mass indistinguishable from a primary pancreatic neoplasm. In patients with a solitary focal lesion surgical biopsy may be necessary to differentiate between metastasis and primary pancreatic carcinoma.

Pancreatic Ductal Adenocarcinoma Radiology Reporting Template: Consensus Statement of the Society of Abdominal Radiology and the American Pancreatic Association

Pancreatic ductal adenocarcinoma is an aggressive malignancy with a high mortality rate. Proper determination of the extent of disease on imaging studies at the time of staging is one of the most important steps in optimal patient management. Given the variability in expertise and definition of disease extent among different practitioners as well as frequent lack of complete reporting of pertinent imaging findings at radiologic examinations, adoption of a standardized template for radiology reporting, using universally accepted and agreed on terminology for solid pancreatic neoplasms, is needed. A consensus statement describing a standardized reporting template authored by a multi-institutional group of experts in pancreatic ductal adenocarcinoma that included radiologists, gastroenterologists, and hepatopancreatobiliary surgeons was developed under the joint sponsorship of the Society of Abdominal Radiologists and the American Pancreatic Association. Adoption of this standardized imaging reporting template should improve the decision-making process for the management of patients with pancreatic ductal adenocarcinoma by providing a complete, pertinent, and accurate reporting of disease staging to optimize treatment recommendations that can be offered to the patient. Standardization can also help to facilitate research and clinical trial design by using appropriate and consistent staging by means of resectability status, thus allowing for comparison of results among different institutions.

Comparison of contrast-enhanced sonography and MRI in displaying anatomic features of cystic pancreatic masses.

OBJECTIVE The purpose of this study was to compare the accuracy rates of unenhanced sonography, contrast-enhanced sonography, and MRI in displaying the anatomic features of cystic pancreatic masses larger than 1.5 mm in diameter. MATERIALS AND METHODS Unenhanced and contrast-enhanced sonographic and MRI examinations of 33 patients who underwent resection of a cystic pancreatic mass were retrospectively reviewed. Two radiologists blinded to the final histologic diagnosis reviewed the images, specifically assessing the presence of intralesional mural nodules and septa. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated on the basis of correlation with surgical findings. Results of unenhanced sonography, contrast-enhanced sonography, and MRI were compared by McNemar test. Correlation of unenhanced and contrast-enhanced sonographic versus pathologic results was established with Spearmans test. Interobserver variability was determined. RESULTS Contrast-enhanced sonography correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 88.8%; positive predictive value, 87.5%; negative predictive value, 94.1%; accuracy, 90.9%) and nodules in six of eight lesions (sensitivity, 75%; specificity, 96%; positive predictive value, 85.7%; negative predictive value, 92.3%; accuracy, 90.9%). MRI correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 61.1%; positive predictive value, 66.6%; negative predictive value, 91.6%; accuracy, 75.7%) and nodules in seven of eight lesions (sensitivity, 87.5%; specificity, 80%; positive predictive value, 58.3%; negative predictive value, 95.2%; accuracy, 81.8%). The difference between the diagnostic accuracy of contrast-enhanced sonography and that of MRI was not significant (p = 0.05, McNemar test) in the identification of septa and nodules. The correlation between contrast-enhanced sonographic findings and pathologic results (Rs = 0.93; p < 0.001) was significantly better than that between sonographic and pathologic results (Rs = 0.52; p < 0.0001). Interobserver agreement had a kappa value of 0.86-0.94. CONCLUSION Contrast-enhanced sonography compares favorably with MRI in displaying the anatomic features of cystic pancreatic masses seen on transabdominal sonography.

Diffuse xanthogranulomatous pyelonephritis: Analysis by computed tomography and sonography

The sonographic and computed tomographic findings in 3 cases of diffuse xanthogranulomatous pyelonephritis are presented along with correlation with the pathological specimens. The combination of the findings in sonography and computed tomography in this condition enables one to make an accurate preoperative diagnosis. Calyces containing pus and/or xanthomatous tissue produced low-level echoes simulating preservation or thickening of the renal parenchyma on sonography. On CT the central low attenuation areas either gave negative values representing abundant xanthomatous tissue seen on gross pathology, or measured in the water density range representing a combination of pus and less abundant xanthomatous tissue.

CT colonography in senior versus nonsenior patients: extracolonic findings, recommendations for additional imaging, and polyp prevalence.

PURPOSE To retrospectively evaluate the frequency of recommendations for additional imaging (RAIs) for important extracolonic findings and polyp prevalence among a cohort of seniors (age ≥ 65 years) and nonseniors (age < 65 years) undergoing low-dose computed tomographic (CT) colonography. MATERIALS AND METHODS Institutional review board approval was obtained for this HIPAA-compliant retrospective study. Four hundred fifty-four patients (204 nonseniors: mean age, 52 years; 250 seniors: mean age, 69 years) underwent CT colonography at an outpatient facility. Cases were prospectively reported by one of four abdominal radiologists with expertise in CT colonography. The dictated reports were reviewed to determine the frequency of polyps (≥6 mm), the number of extracolonic findings, and the number of RAIs generated. The Fisher exact test was used to compare the percentage of seniors and nonseniors with at least one reported polyp, with at least one extracolonic finding, as well as the frequency of RAIs. RESULTS The percentage of patients with at least one reported polyp was 14.2% (29 of 204) for the nonsenior group and 13.2% (33 of 250) for seniors, which was not significantly different (P = .772). The percentage of patients with at least one extracolonic finding was 55.4% (113 of 204) for nonseniors and 74.0% (185 of 250) for seniors (P < .0001). The percentage of patients in which an RAI was suggested was 4.4% (nine of 204) for nonseniors and 6.0% (15 of 250) for seniors, which was not significantly different (P = .450). CONCLUSION Extracolonic findings were more frequent in seniors than in nonseniors; however, there was no significant difference in the frequency of RAIs between the two groups. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11102144/-/DC1.

Computed tomography of the abnormal appendix

This report describes the CT features of 29 abnormal appendices visualized during abdominal CT examinations. There were 22 cases of acute appendicitis, five mucoceles, and two mucinous adenocarcinomas of the appendix. The inflammed appendix appeared either as a fluid-filled slightly distended structure or as a collapsed small tubular structure. It was visualized on either cross or longitudinal sections and showed slight circumferential wall thickening. Periappendiceal inflammation was detected in 19 cases and intraluminal appendicoliths in six cases. Mucocele appeared as a larger fluid-filled round, oval, or tubular structure having a thin, sharp wall, low density contents, and no periappendiceal inflammation. Mucinous carcinoma appeared either as a single or as multiloculated, irregular shaped cystic lesion with solid elements. Infiltration of cecum and terminal ileum was seen in one case. In five cases the abnormal appendix was not recognized initially and was identified only after repeat 5 X 5 mm sections were obtained. During CT examination, demonstration of an abnormal appendix establishes the source of the abdominal pathology and helps greatly in the differential diagnosis.