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Objective: The objective of our study was to describe the T1 and T2 signal intensity characteristics of papillary renal cell carcinoma (RCC) and clear cell RCC with pathologic correlation., Materials and Methods: Of 539 RCCs, 49 tumors (21 papillary RCCs and 28 clear cell RCCs) in 45 patients were examined with MRI. Two radiologists retrospectively and independently assessed each tumor's T1 and T2 signal intensity qualitatively and quantitatively (i.e., the signal intensity [SI] ratio [tumor SI / renal cortex SI]). Of the 49 tumors, 37 (76%) were assessed for pathology features including tumor architecture and the presence of hemosiderin, ferritin, necrosis, and fibrosis. MRI findings and pathology features were correlated. Statistical methods included summary statistics and Wilcoxon's rank sum test for signal intensity, contingency tables for assessing reader agreement, concordance rate between the two readers with 95% CIs, and Fisher's exact test for independence, all stratified by RCC type., Results: Papillary RCCs and clear cell RCCs had a similar appearance and signal intensity ratio on T1-weighted images. On T2-weighted images, most papillary RCCs were hypointense (reader 1, 13/21; reader 2, 14/21), with an average mean signal intensity ratio for both readers of 0.67 +/- 0.2, and none was hyperintense, whereas most clear cell RCCs were hyperintense (reader 1, 21/28; reader 2, 17/28), with an average mean signal intensity ratio for both readers of 1.41 +/- 0.4 (p < 0.05). A tumor T2 signal intensity ratio of < or = 0.66 had a specificity of 100% and sensitivity of 54% for papillary RCC. Most T2 hypointense tumors exhibited predominant papillary architecture; most T2 hyperintense tumors had a predominant nested architecture (p < 0.05)., Conclusion: On T2-weighted images, most papillary RCCs are hypointense and clear cell RCCs, hyperintense. The T2 hypointense appearance of papillary RCCs correlated with a predominant papillary architecture at pathology.

Objective: The purpose of this study was to illustrate the varied MDCT and MRI appearances of hypervascular and hemorrhagic pancreatic conditions and their mimics., Conclusion: Pancreatic hypervascular conditions are easily detected at multiphasic contrast-enhanced MDCT and MRI. Hemorrhagic pancreatic abnormalities are best depicted with unenhanced CT and, especially, fat-suppressed T1-weighted MRI. Familiarity with the spectrum of possible underlying causes and the imaging features and conditions that can act as mimics assists radiologists in making an accurate presumptive diagnosis.

Objective: The objective of our study was to determine the predictive value of percutaneous imaging-guided biopsy of peritoneal and omental masses., Materials and Methods: A retrospective study of 111 patients who underwent biopsy of a peritoneal or omental mass from 1998 to 2006 was performed. Biopsy results were classified as diagnostic (malignant or benign) or nondiagnostic. Sensitivity, specificity, and negative predictive value (NPV) were calculated for all patients, and the Fisher-Freeman-Halton exact test was used to determine whether test characteristics varied by patient history (presence of a known cancer), mass size (<4 cm vs >or= 4 cm), and needle size (biopsies with fine needles vs biopsies with fine and large needles)., Results: The overall diagnostic rate was 89% (99/111); there were 86 true-positive, one false-positive, six true-negative, and six false-negative results (sensitivity, 93% [86/92]; specificity, 86% [6/7]; NPV, 50% [6/12]). There were no statistically significant differences between patients with and without known cancer. Among 79 patients with known cancer, 52 (66%) had metastatic disease from the known cancer; in eight (10%) patients, the biopsy result yielded new primary cancers. Of 32 patients with no known cancer, 23 (72%) had malignant results. Biopsy test characteristics did not differ with respect to mass or needle size. Minor complications were seen in three (3%) patients., Conclusion: Percutaneous imaging-guided biopsy of peritoneal and omental masses is a safe, effective procedure that is useful in clinical practice. A second malignancy was revealed in a substantial number of patients with a known primary cancer. A new malignancy was diagnosed in most patients without a history of cancer.

Objective: The purpose of this study was to report on clinical experience with and observations made during primary CT-guided percutaneous catheter drainage of acute necrotizing pancreatitis and to compare results among patients with sterile and those with infected necrosis., Materials and Methods: We reviewed clinical, radiologic, and bacteriologic data on 35 patients (23 men, 12 women; mean age, 50 years; range, 21-83 years) with acute necrotizing pancreatitis refractory to standard medical care who underwent CT-guided percutaneous catheter drainage with 12- to 22-French catheters. Experiences with two subgroups were compared. One group consisted of 22 patients, 10 with multisystem organ failure, who presented with sterile necrosis (median Atlanta score, 1.3; range, 0-3). The other group consisted of 13 patients, one with multisystem organ failure, who presented with infected necrosis (median Atlanta score, 0.4; range, 0-3). Differences between the group with sterile and the group with infected necrosis were analyzed with the Fisher-Holton exact and Mann-Whitney U tests., Results: Among 35 patients, 17 (49%) were treated successfully with CT-guided percutaneous catheter drainage alone. The effectiveness of CT-guided percutaneous catheter drainage in patients with sterile necrosis (11/22, 50%) was not significantly different from that of drainage in patients with infected necrosis (6/13, 46%). Among 11 patients with multisystem organ failure (10 with sterile necrosis, one with infected necrosis), only four (36%) were treated successfully with CT-guided percutaneous catheter drainage alone; five patients (45%) died. Among 24 patients without multisystem organ failure, 13 (54%) were treated successfully with CT-guided percutaneous catheter drainage alone; one patient died., Conclusion: In our experience, primary CT-guided percutaneous catheter drainage was successful for approximately one half of the patients with acute necrotizing pancreatitis. The presence of multisystem organ failure appears to be a more important indicator of outcome than does the presence of infection.

Objective: The objective of our study was to evaluate whether CT can be used to predict the pathologic subtypes of pancreatic intraductal papillary mucinous neoplasms (IPMNs)., Materials and Methods: Three radiologists, blinded to the pathologic IPMN subtype, retrospectively and independently reviewed the preoperative CT scans of 38 patients with surgically resected pancreatic IPMN: 11 intraductal papillary mucinous adenomas, 11 intraductal papillary mucinous carcinomas, and 16 intraductal papillary mucinous carcinomas with invasion. The patients, 16 women and 22 men, ranged in age from 38 to 80 years (mean age, 64.3 years). CT findings were correlated with each pathologic subtype using the chi-square (two-sided) test and analysis of variance. Interobserver agreement of the CT diagnosis of pathologic subtype and agreement between the CT diagnosis and pathologic subtype were also studied (kappa statistic)., Results: Predominant main pancreatic duct (MPD) involvement (p = 0.04) and a wide (> 1 cm) connection of a side-branch lesion with the MPD (p = 0.03) correlated with intraductal papillary mucinous carcinoma with invasion. Tumor size, MPD diameter, number of tumors per patient, number of pseudoseptations per tumor, common bile duct dilatation, enlarged lymph nodes, intraductal calcifications, papillary bulging, and presence and size of a solid mass yielded no statistically significant relationship with pathologic subtype. Both interobserver agreement of CT diagnosis (range, 0.004-0.359) and agreement between CT diagnosis and pathologic subtype (range, 0.046-0.317) ranged from slight to fair., Conclusion: Prediction of the pathologic subtypes of pancreatic IPMNs by CT is limited. Predominant MPD involvement and a wide connection of a side-branch lesion with the MPD are the only CT findings that can be used to predict the pathologic subtype of pancreatic IPMN.

Objective: Imaging-guided biopsies of solid pancreatic masses are performed with either CT or endoscopic sonography at our institution. We compared test characteristics of fine-needle aspiration biopsies guided using CT with those guided using endoscopic sonography and secondarily evaluated for an effect of mass size., Materials and Methods: Of 70 solid pancreatic masses, 43 (mean size, 4.4 cm; range, 1.5-10.3 cm) underwent fine-needle (20- to 22-gauge) aspiration biopsy with CT guidance and 27 (mean size, 2.3 cm; range, 1.0-5.0 cm) underwent fine-needle (22-gauge) aspiration biopsy with endoscopic sonography guidance. The diagnostic rate, sensitivity, and negative predictive value (NPV) for each technique were compared using Fisher's exact test before and after stratifying masses by size as small (< or = 3 cm) or large (> 3 cm)., Results: The overall diagnostic rate, sensitivity, and NPV of fine-needle aspiration biopsies guided using CT (97.7%, 94.9%, and 60%, respectively) were not significantly different from those guided using endoscopic sonography (88.9%, 85%, and 57.1%, respectively). Among small masses, the diagnostic rate and sensitivity for biopsies guided using CT (100% and 100%, respectively) were not significantly different from those for biopsies guided using endoscopic sonography (90.9% and 93.8%, respectively). Among large masses, the diagnostic rate and sensitivity (96.6% and 92.3%, respectively) for biopsies guided using CT were not significantly different from those for biopsies guided using endoscopic sonography (83.3% and 50%, respectively)., Conclusion: When biopsying solid pancreatic masses with fine needles, procedures guided with CT and those guided with endoscopic sonography have similar test characteristics regardless of mass size.

Objective: We conducted this study to evaluate whether CT scans could be used to differentiate hepatic venoocclusive disease from hepatic graft-versus-host disease in patients treated with hematopoietic stem cell transplantation., Subjects and Methods: We retrospectively evaluated 18 patients (eight women, 10 men; mean age, 42.4 years) after hematopoietic stem cell transplantation with biopsy-proven hepatic venoocclusive disease (n = 5), hepatic graft-versus-host disease (n = 6), or both (n = 7). Two radiologists reviewed abdominal and pelvic CT scans for hepatomegaly (> 18 cm), splenomegaly (> 13 cm), size of main portal and right hepatic veins, presence of periportal edema, gallbladder wall edema, hydropic gallbladder, ascites, and small-bowel wall thickening. CT and histopathology findings were correlated using analysis of variance and Fisher-Free-man-Holton tests., Results: Ascites and periportal edema were present in all five patients with venoocclusive disease, but of six patients with graft-versus-host disease, ascites was seen in two (p < 0.05) and periportal edema in only one (p < 0.05). Small-bowel wall thickening was encountered in five patients with graft-versus-host disease and in none with venoocclusive disease (p < 0.05). The right hepatic vein diameter in patients with venoocclusive disease (mean, 0.27 cm) was significantly smaller than the right hepatic vein diameter in patients with graft-versus-host disease (mean, 0.87 cm; p < 0.05)., Conclusion: In patients treated with hematopoietic stem cell transplantation, CT findings of periportal edema, ascites, and a narrow right hepatic vein suggest venoocclusive disease rather than graft-versus-host disease. Small-bowel wall thickening suggests graft-versus-host disease.

Objective: The aim of this study is to describe the MRI features of focal splenic lesions in patients with disseminated tuberculosis., Conclusion: Tuberculous focal splenic lesions are small, multiple, and most often associated with splenomegaly. Signal intensities vary on both T1- and T2-weighted images. Two different enhancement patterns are noted: peripheral enhancement and gradual peripheral enhancement with complete fill-in.

Objective: We determined the prevalence of incidental extraurinary findings at MDCT urography in patients with hematuria and evaluated their impact on subsequent imaging costs., Materials and Methods: Three hundred forty-four consecutive patients with hematuria were evaluated with MDCT urography. Incidental extraurinary findings were classified into three categories according to their clinical significance (high, moderate, and low). Medical records were reviewed, and the cost of additional imaging examinations was calculated using 2002 Medicare reimbursements., Results: Extraurinary findings were detected in 259 patients (75.3%). Of these, 62 patients (18.0%) had highly clinically significant findings, including three cancers. Only 20 (32.3%) of the 62 patients with highly clinically significant findings underwent additional imaging for findings of high clinical significance; 10 (16.1%) were followed clinically, and 32 (51.6%) were not evaluated. The most prevalent highly clinically significant findings were pulmonary nodules and lymphadenopathy. Of the 344 patients studied, 116 (33.7%) had findings in which the highest level of clinical significance was moderate; 81 (23.5%) had findings of only low clinical significance. Nine patients (2.6%) underwent additional imaging for findings of moderate or low clinical significance. Overall, 29 patients (8.4%) underwent further imaging at a cost of $14,231 (average of $41.37 per patient)., Conclusion: Although incidental extraurinary findings were common at MDCT urography, only a small percentage of patients were imaged further. MDCT urography, when used to evaluate patients with hematuria, detects extraurinary disease without a substantial increase in per-patient imaging costs.

Objective: We evaluated the safety of the universal use of the nonionic iodinated contrast agent iopromide in patients undergoing CT in a large urban teaching hospital., Subjects and Methods: For 2 years, we prospectively recorded all adverse events temporally associated with the administration of iopromide in 29,508 consecutive patients undergoing contrast-enhanced CT at our institution. The types, intensities, treatments, and outcomes of adverse events were recorded along with relevant patient history, including risk factors. Descriptive analyses of the variables, comparisons of means, and proportions using Student's t and chi-square tests, and logistic regressions were conducted., Results: Adverse events were observed in 211 patients (0.7%) and were categorized as follows: urticaria (n = 161), facial or laryngeal edema (n = 13), bronchospasm (n = 8), severe nausea or vomiting (n = 10), or other (n = 19). One hundred eighty-eight adverse events (89%) were rated mild, 19 moderate (9%), and four severe (2%), including one fatality. Adverse events required treatment in 89 patients (42%). A history of allergy was present in 92 patients (44%), and 29 (14%) had a prior contrast reaction. Other relevant risk factors were identified in 63 patients (30%). No relationship existed between the occurrence of adverse events and any of the following: patient age, dose of iodine administered, or time of study (i.e., month, season, and year). Women (p < 0.001) and outpatients (p < 0.001) had a statistically significant higher incidence of adverse events., Conclusion: The universal use of iopromide as an IV CT contrast agent has a favorable safety profile.

Objective: The purpose of this study was to describe the MRI features of tuberculosis of the pancreas., Conclusion: Pancreatic tuberculosis can be focal or diffuse. If focal, it presents as a sharply delineated mass located in the pancreatic head, showing heterogeneous enhancement. Lesions are hypointense on fat-suppressed T1-weighted images and a mixture of hypo- and hyperintense on T2-weighted images. The appearances of common bile duct and main pancreatic duct are normal. Diffuse involvement is characterized by pancreatic enlargement with narrowing of the main pancreatic duct and heterogeneous enhancement. Signal intensity abnormalities indicating diffuse involvement include hypointensity on fat-suppressed T1-weighted images and hyperintensity on T2-weighted images.

Objective: The purpose of this study was to describe the prevalence and CT features of the accessory spleen., Conclusion: Accessory spleens are present in 16% of patients undergoing contrast-enhanced abdominal CT. Typically, accessory spleens appear on CT scans as well-marginated, round masses that are smaller than 2 cm and enhance homogeneously on contrast-enhanced images. When accessory spleens are smaller than 1 cm, their attenuation may be lower than that of the spleen because of partial volume effects. Their most frequent location (22%) is posteromedial to the spleen; anterolateral to the upper pole of the left kidney; and lateral, posterior, and superior to the tail of the pancreas. Familiarity with these characteristic features may differentiate them from other pathologic findings in the upper abdomen.

Objective: This study was conducted to describe the CT features of acute gastrointestinal graft-versus-host disease in adults and to correlate these findings with the pathologic grades of disease severity., Materials and Methods: Patients (n = 22) with a history of allogeneic bone marrow transplantation and pathologically confirmed acute gastrointestinal graft-versus-host disease underwent contrast-enhanced (n = 13) and unenhanced (n = 9) CT. CT scans were retrospectively evaluated for intestinal and extraintestinal abnormalities by two radiologists who were unaware of the biopsy results. The CT findings were correlated with the pathologic grade of disease severity using the Pearson's correlation coefficient and the two-tailed nonparametric Spearman's rank correlation coefficient., Results: CT features included small-bowel wall thickening (22/22), engorgement of the vasa recta adjacent to affected bowel segments (20/22), stranding of the mesenteric fat (16/22), large-bowel wall thickening (13/22), bowel dilatation proximal to thickened wall segments (5/22), ascites (10/22), periportal edema (8/22), mucosal enhancement (7/13), and serosal enhancement (4/13). The wall thickening had a discontinuous distribution in nine patients (41%). Bowel wall thickening was associated with high-grade graft-versus-host disease in patients in whom the distal esophagus (p = 0.015), ileum (p = 0.034), or ascending colon (p = 0.05) was involved. Increasing numbers of thickened bowel segments correlated with high-grade graft-versus-host disease (r = 0.548, p = 0.008). Increasing numbers of abnormal CT findings did not correlate with high-grade graft-versus-host disease (r = 0.117, p = 0.604)., Conclusion: A variety of bowel abnormalities can be seen on CT in patients with acute graft-versus-host disease. CT findings associated with high-grade graft-versus-host disease are thickening of the distal esophagus, ileum, or ascending colon, as well as increasing numbers of thickened bowel wall segments.

Objective: Macrocystic serous adenoma is a rare benign pancreatic neoplasm, recently described in the pathology literature. We describe the CT and MR imaging features in a series of five consecutive pathologically proven cases., Materials and Methods: Of seven cases fulfilling the pathology criteria for macrocystic serous adenoma over an 11-year period, five patients underwent preoperative CT and MR imaging at our institution. In addition to the clinical presentation and pathologic features of the tumor, the following CT and MR imaging features were reviewed: size and location; wall thickness; internal septations; and presence of mural nodules, papillary projections, or calcifications., Results: All patients but one were women (age range, 36-78 years; mean age, 48.6 years). The sizes of the tumors ranged from 1.5 to 5.0 cm (mean, 3.1 cm). Three (60%) of five tumors were located in the pancreatic head. The wall measured less than 2 mm in four lesions and 4 mm in one. No mural nodules, papillary projections, or calcifications were present. Lesions were unilocular (n = 3) or bilocular (n = 2). Excellent correlation of imaging features with gross pathology was observed., Conclusion: On CT and MR imaging, the macrocystic variant of serous adenoma typically appears as a small (< 5 cm), uni- or bilocular cyst with a thin (< 2 mm) wall that lacks mural nodules or calcifications. The imaging appearance of macrocystic serous adenoma is distinctly different from that of microcystic serous cystadenoma, but the imaging appearance of macrocystic serous adenoma is indistinguishable from mucinous cystadenoma and cystadenocarcinoma of the pancreas.

Objective: The purpose of this study was to analyze the correlation between pneumatosis or portomesenteric venous gas, or both, the severity of mural involvement, and the clinical outcome in patients with small- or large-bowel ischemia., Materials and Methods: CT scans of 23 consecutive patients presenting with pneumatosis or portomesenteric venous gas caused by bowel ischemia were reviewed. The presence and extent of both CT findings were compared with the clinical outcome in all patients and with the severity and extent of ischemic bowel wall damage as determined by surgery (15 patients), autopsy (three patients), or follow-up (five patients)., Results: Seven patients showed isolated pneumatosis, and 16 patients showed portomesenteric venous gas with or without pneumatosis (11 and five patients, respectively). Pneumatosis and portomesenteric venous gas were associated with transmural bowel infarction in 14 (78%) of 18 patients and 13 (81%) of 16 patients, respectively. Nine patients (56%) with portomesenteric venous gas died. Of seven patients with infarction limited to one bowel segment (jejunum, ileum, or colon), only one patient (14%) died, whereas of the 10 patients with infarction of two or three bowel segments, eight patients (80%) died., Conclusion: CT findings of pneumatosis intestinalis and portomesenteric venous gas due to bowel ischemia do not generally allow prediction of transmural bowel infarction, because they may be observed in patients with only partial ischemic bowel wall damage. The clinical outcome of patients with bowel ischemia with these CT findings seems to depend mainly on the severity and extent of their underlying disease.

Objective: The objective of this study was to determine the prevalence and radiologic features of postoperative complications after Swedish laparoscopic adjustable gastric banding surgery and to emphasize the role of the radiologist in the follow-up of those patients, especially in the treatment of complications., Materials and Methods: We reviewed the radiologic findings in 218 consecutive morbidly obese patients after laparoscopic placement of the Swedish gastric banding system. Radiographic studies of the stomach (obtained with liquid barium sulfate suspension) were performed before surgery and 1 month after band placement in every patient. Additional studies in symptomatic patients were performed when needed., Results: Surgical complications found included misplacement of the band (five patients, 2.3%), slippage of the band (17 patients, 7.8%), and pouch enlargement (eight patients, 3.7%). Technical problems encountered were inversion of the access port (three patients, 1.4%), leakage of the device (two patients, 0.9%), and spontaneous decrease of the stoma size caused by gastritis (seven patients, 3.2%) or the hyperosmolar properties of the IV contrast material (12 patients, 5.5%). Intrinsic abnormalities of gastroesophageal tract seen included trapping of food in the stoma (four patients, 1.8%) and esophagitis (11 patients, 5%)., Conclusion: Although, according to the available data, the gastric banding operation with the Swedish band meets the criteria of a low-risk laparoscopic alternative treatment of morbid obesity, the radiologic appearances of various complications may be seen on the images of patients who have undergone the procedure. The radiologist plays a key role in the early detection of those complications and treatment of specific abnormalities.