Search

Purpose To identify computed tomographic (CT) findings that are predictive of recurrence of colonic diverticulitis. Materials and Methods Institutional review board approval was obtained for this HIPAA-compliant, retrospective cohort study. Six abdominal fellowship-trained radiologists reviewed the CT studies of 440 consecutive subjects diagnosed with acute colonic diverticulitis between January 2004 and May 2008 to determine the involved segments, maximum wall thickness in the inflamed segment, severity of diverticulosis, presence of complications (abscess, fistula, stricture, or perforation), and severity of the inflammation. Electronic medical records were reviewed for a 5-year period after the patients' first CT study to determine clinical outcomes. Predictors of diverticulitis recurrence were assessed with univariate and multiple Cox proportional hazard regression models. Results Colonic diverticulitis most commonly involved the rectosigmoid (70%, 309 of 440) and descending (30%, 133 of 440) colon segments. Complicated diverticulitis was present in 22% (98 of 440) of patients. On the basis of the results of univariate analysis, significant predictors of diverticulitis recurrence were determined to be maximum colonic wall thickness in the inflamed segment (hazard ratio [HR], 1.07 per every millimeter of increase in wall thickness; P < .001), presence of a complication (HR, 1.75; P = .002), and subjective severity of inflammation (HR, 1.36 for every increase in severity category; P value for linear trend = .003). The difference in maximum wall thickness in the inflamed segment (HR, 1.05 per millimeter; P = .016) and subjective inflammation severity (HR, 1.29 per category; P = .018)remained statistically significant in a Cox multiple regression model. Conclusion Maximum colonic wall thickness and subjective severity of acute diverticulitis allow prediction of recurrent diverticulitis and may be useful for stratifying patients according to the need for elective partial colectomy. © RSNA, 2017 Online supplemental material is available for this article.

Purpose To determine if the allergic-like breakthrough reaction rate of intravenous corticosteroid prophylaxis administered 5 hours before contrast material-enhanced computed tomography (CT) is noninferior to that of a traditional 13-hour oral regimen. Materials and Methods Institutional review board approval was obtained and informed consent waived for this retrospective noninferiority cohort study. Subjects (n = 202) who completed an accelerated 5-hour intravenous corticosteroid premedication regimen before low-osmolality contrast-enhanced CT for a prior allergic-like or unknown-type reaction to iodine-based contrast material from June 1, 2008, to June 30, 2016, were identified. The breakthrough reaction rate was compared by using the Farrington and Manning noninferiority likelihood score to test subjects premedicated with a traditional 13-hour oral regimen (2.1% [13 of 626]). All subjects were premedicated for a prior allergic-like or unknown-type reaction to iodine-based contrast material. A noninferiority margin of 4.0% was selected to allow for no more than a clinically negligible 6.0% breakthrough reaction rate in the cohort that received 5-hour intravenous corticosteroid prophylaxis. Results The breakthrough reaction rate for 5-hour intravenous prophylaxis was 2.5% (five of 202 patients; 95% confidence interval: 0.8%, 5.7%), which was noninferior to the 2.1% (13 of 626 patients; 95% confidence interval: 1.1%, 3.5%) rate for the 13-hour regimen (P = .0181). The upper limits of the confidence interval for the difference between the two rates was 3.7% (0.4%; 95% confidence interval: -1.6%, 3.7%), which was within the 4.0% noninferiority margin. All breakthrough reactions were of equal or lesser severity to those of the index reactions (two severe, one moderate, and one mild reaction). Conclusion Accelerated intravenous premedication with corticosteroids beginning 5 hours before contrast-enhanced CT has a breakthrough reaction rate noninferior to that of a 13-hour oral premedication regimen. © RSNA, 2017.

Purpose: To estimate the effect of an oral 13-hour inpatient corticosteroid premedication regimen on length of stay, hospital cost, and hospital-acquired infections (HAIs) by using a combination of real and hypothetical study populations., Materials and Methods: Institutional review board approval was obtained and informed consent waived for this HIPAA-compliant retrospective study. Inpatients who received an oral 13-hour corticosteroid premedication regimen before contrast material-enhanced CT (n = 1424) from 2008 to 2013 were matched by age, sex, and year when CT was performed to a control cohort (n = 1425) of patients who underwent contrast-enhanced CT without premedication and who had similar rates of 13 comorbid diseases. Length of stay in the hospital and time from admission to CT were compared by using the Mann-Whitney U test. Rates of prospectively reported HAIs were compared by using χ(2) tests. The indirect cost and risk of HAI with premedication were estimated by using published data., Results: Premedicated inpatients had a significantly longer median length of stay (+25 hours; 158 vs 133 hours, P < .001), a significantly longer median time to CT (+25 hours, 42 vs 17 hours, respectively; P < .001), and a significantly greater risk of HAI (5.1% [72 of 1424] vs 3.1% [44 of 1424], respectively; P = .008) compared with nonpremedicated control subjects. On the basis of these data and existing references, the prolonged length of stay was estimated to result in 0.04 HAI-related deaths and a cost of $159 131 (in U.S. dollars) for each prevented reaction of any severity and 32 HAI-related deaths and a cost of $131 211 400 for each prevented reaction-related death., Conclusion: Oral 13-hour inpatient corticosteroid prophylaxis is associated with substantial cost relative to its modest benefit, and may cause more indirect harm than the direct harm that it prevents., ((©) RSNA, 2015.)

Purpose: To compare serum creatinine (SCr) level- and estimated glomerular filtration rate (eGFR)-based screening methods for identifying adult inpatients at risk for contrast medium-induced nephrotoxicity (CIN)., Materials and Methods: Institutional review board approval was obtained; informed consent was waived for this HIPAA-compliant retrospective study. Computed tomographic examinations performed during 10 years in adult inpatients with stable renal function were identified (n = 28 390). The proportion of inpatients meeting various eGFR (≥60, <60, <45, <30, 30-44, 45-59 mL/min/1.73 m(2)) and SCr (<1.5, ≥1.5, ≥1.6, ≥1.7, ≥1.8, ≥1.9, ≥2.0 mg/dL) thresholds were contrasted with each other and with published guidelines (≥2.0 mg/dL [SCr] and <45 mL/min/1.73 m(2) [eGFR]) using McNemar and binomial tests., Results: Most inpatients were considered low risk for CIN with commonly used thresholds: 92.6% (26 285 of 28 390) had SCr <1.5 mg/dL; 91.3% (25 922 of 28 390) had eGFR of ≥45 mL/min/1.73 m(2). Using SCr threshold of ≥1.5 mg/dL, identified inpatients had the following eGFRs: 19.6% (413 of 2105), 45-59 mL/min/1.73 m(2); 51.1% (1075 of 2105), 30-44 mL/min/1.73 m(2); 28.6% (603 of 2105), <30 mL/min/1.73 m(2); and 0.7% (14 of 2105), ≥60 mL/min/1.73 m(2) . Using SCr threshold of ≥2.0 mg/dL, identified inpatients had the following eGFRs: 100% (658 of 658), <45 mL/min/1.73 m(2); 74.6% (491 of 658), <30 mL/min/1.73 m(2). Threshold of SCr ≥2.0 mg/dL could not be used to identify eGFR <30 mL/min/1.73 m(2) in 0.4% (112 of 28 390) and <45 mL/min/1.73 m(2) in 6.4% (1810 of 28 390) of all inpatients. Using eGFR <45 mL/min/1.73 m(2) instead of SCr of ≥1.5 mg/dL would result in a significant but small increase in identified inpatients (8.7% [2468 of 28 390; 95% confidence interval: 8.4%, 9.0%] vs 7.4% [2105 of 28 390; 95% confidence interval: 7.1%, 7.7%]; P < .0001)., Conclusion: Screening using eGFR <45 mL/min/1.73 m(2) instead of common SCr thresholds would significantly increase the number of inpatients identified to be at risk for CIN but would reduce misidentification of a large number of inpatients at low risk according to eGFR criteria., (© RSNA, 2013.)

Purpose: To determine the effect of intravenous (IV) low-osmolality iodinated contrast material (LOCM) on the development of post-computed tomography (CT) acute kidney injury (AKI), stratified by pre-CT estimated glomerular filtration rate (eGFR), in patients with stable renal function., Materials and Methods: Institutional review board approval was obtained and patient consent waived for this HIPAA-compliant, retrospective study. CT examinations performed over a 10-year period on unique adult inpatients with sufficient serum creatinine (SCr) data and stable renal function (difference between baseline and pre-CT SCr within 0.3 mg/dL and 50% of baseline) were identified. A 1:1 propensity score matched cohort analysis with multivariate analysis of effects was performed with post-CT AKI as the primary outcome measure (8826 nonenhanced and 8826 IV contrast agent-enhanced CT studies in 17 652 patients). Propensity matching was performed with respect to likelihood of receiving IV contrast material (19 tested covariates). Post-CT AKI with Acute Kidney Injury Network SCr criteria was the primary endpoint. A stepwise multivariate conditional logistic regression model was performed to identify the effect of IV LOCM on post-CT AKI., Results: After 1:1 propensity matching, IV LOCM had a significant effect on the development of post-CT AKI (P = .04). This risk increased with decreases in pre-CT eGFR (≥ 60 mL/min/1.73 m(2): odds ratio, 1.00; 95% confidence interval: 0.86, 1.16; 45-59 mL/min/1.73 m(2): odds ratio, 1.06; 95% confidence interval: 0.82, 1.38; 30-44 mL/min/1.73 m(2): odds ratio, 1.40; 95% confidence interval: 1.00, 1.97; <30 mL/min/1.73 m(2): odds ratio, 2.96; 95% confidence interval: 1.22, 7.17)., Conclusion: IV LOCM is a nephrotoxic risk factor in patients with a stable eGFR less than 30 mL/min/1.73 m(2), with a trend toward significance at 30-44 mL/min/1.73 m(2). IV LOCM does not appear to be a nephrotoxic risk factor in patients with a pre-CT eGFR of 45 mL/min/1.73 m(2) or greater.

Purpose: To determine whether the intravenous administration of low-osmolality contrast material is associated with exacerbation of disease-related symptoms in patients with myasthenia gravis., Materials and Methods: This HIPAA-compliant, retrospective cohort study was approved by the institutional review board. The requirement to obtain patient consent was waived. Computed tomography (CT) was performed in 267 patients with clinically confirmed myasthenia gravis between January 1, 1995, and December 31, 2011. CT was performed without intravenous administration of contrast material in 155 patients and with intravenous administration of low-osmolality contrast material in 112. Electronic medical records were searched to identify myasthenia gravis-related symptoms before (≤ 14 days) and after (≤ 45 days) each CT examination. The Mantel-Cox log-rank test was used to compare the time to symptom progression between the two groups. The Fisher exact test was used to compare rates of disease-related symptoms during three time periods: (a) 0-1 day after CT, (b) 2-7 days after CT, and (c) 8-45 days after CT., Results: The unenhanced and contrast-enhanced CT groups had similar thymectomy rates (P = .97) and disease-related symptom trends before CT (P = .58). The contrast-enhanced CT group was associated with a significant reduction in time to disease-related symptom progression following CT (median time to onset of symptom progression, 2.5 days with contrast-enhanced CT vs 14.0 days with unenhanced CT; P = .05). There were significantly more disease-related symptom exacerbations within 1 day of CT in the contrast-enhanced CT group compared with the unenhanced CT group (6.3% [seven of 112 patients] vs 0.6% [one of 155 patients], respectively; P = .01). Acute exacerbations were primarily respiratory (five patients with new-onset dyspnea [four in contrast-enhanced CT group and one in unenhanced CT group], two patients with progressive dyspnea [both in the contrast-enhanced CT group], and one patient with progressive weakness [in contrast-enhanced CT group]). There was no difference in symptoms between groups at 2-7 days (P = .70) or 8-45 days (P = .99)., Conclusion: Intravenous administration of low-osmolality contrast material is significantly associated with exacerbation of myasthenia gravis-related symptoms. Exacerbations most commonly manifest as new or progressive acute respiratory compromise.

Purpose: To determine whether intravenous low-osmolality iodinated contrast material is associated with post-computed tomography (CT) acute kidney injury (AKI)., Materials and Methods: Institutional review board approval was obtained and patient consent waived for this HIPAA-compliant retrospective study. CT examinations performed over a 10-year period in adult inpatients with sufficient serum creatinine (SCr) data were identified. A one-to-one propensity-matched matched cohort analysis with multivariate analysis of effects was performed with post-CT AKI as the primary outcome measure (10,121 unenhanced and 10,121 intravenous contrast-enhanced CT examinations in 20,242 patients). Propensity matching was performed with respect to likelihood of patient receiving intravenous contrast material (36 tested covariates). The primary endpoint was post-CT AKI by using Acute Kidney Injury Network SCr criteria; the secondary endpoint was post-CT AKI by using traditional SCr criteria for contrast material-induced nephrotoxicity (CIN; SCr increase ≥0.5 mg/dL [44.20 μmol/L] or ≥25%). Multivariate subgroup threshold analysis was performed (SCr <1.5 [<132.60 μmol/L]; ≥1.5 to ≥2.0 mg/dL [≥132.60 to ≥176.80 μmol/L]) and adjusted for assigned propensity scores., Results: Intravenous low-osmolality iodinated contrast material had a significant effect on the development of post-CT AKI for patients with pre-CT SCr levels of 1.6 mg/dL (141.44 μmol/L) or greater (odds ratio, 1.45; 95% confidence interval [CI]: 1.11, 1.89;P = .007). This effect strengthened as pre-CT SCr increased. Patients with stable SCr less than 1.5 mg/dL (132.60 μmol/L) were not at risk for developing CIN (P = .25, power > 95%). Both endpoints demonstrated similar results (eg, SCr ≥1.6 mg/dL [141.44 μmol/L] by using traditional CIN criteria: odds ratio, 1.64; 95% CI: 1.18, 2.28; P = .003). Post-CT AKI was prevalent in both the unenhanced and contrast-enhanced CT subgroups, and it increased with increases in pre-CT SCr. Many risk factors contributed to development of post-CT AKI, regardless of iodinated contrast material., Conclusion: Intravenous low-osmolality iodinated contrast material is a nephrotoxic risk factor, but not in patients with a stable SCr level less than 1.5 mg/dL. Many factors other than contrast material can affect post-CT AKI rates., (RSNA, 2013)

Purpose: To evaluate the effect of abruptly substituting gadobenate dimeglumine for gadopentetate dimeglumine on allergic-like reactions., Materials and Methods: The institutional review board approved and waived patient consent for this HIPAA-compliant retrospective study. Allergic-like reactions related to gadolinium-based contrast media were assessed 2 years before and 3.5 years after gadobenate dimeglumine was substituted for gadopentetate dimeglumine. Reaction rates and severity were compared by using χ(2) tests, Fisher exact tests, odds ratios (ORs), and confidence intervals (CIs)., Results: Allergic-like reactions (137 mild, 19 moderate, and six severe) occurred in 162 (0.15%) of 105 607 injections of gadolinium-based contrast media (gadopentetate dimeglumine, 31 540; gadobenate dimeglumine, 66 152; other, 7915). Gadobenate dimeglumine was associated with significantly more overall (0.19% [123 of 66 152] vs 0.08% [24 of 31 540]; OR, 2.4; 95% CI: 1.6, 3.8; P < .0001) and mild (0.16% [107 of 66 152] vs 0.06% [18 of 31 540]; OR, 2.8; 95% CI: 1.7, 4.7; P < .0001) allergic-like reactions than was gadopentetate dimeglumine. The reaction rate for gadobenate dimeglumine peaked (maximum per quarter, 0.38% [16 of 4262]; minimum per quarter, 0.07% [three of 4237]) in the 2nd year after it replaced gadopentetate dimeglumine (maximum per quarter, 0.10% [four of 4122]; minimum per quarter, 0.05% [two of 4222]) and then declined in the 3rd year. The final gadobenate dimeglumine reaction rate (last 3 quarters, 0.12% [17 of 14 387]) did not significantly differ from the original baseline reaction rate with gadopentetate dimeglumine., Conclusion: After gadobenate dimeglumine was substituted for gadopentetate dimeglumine, a significant transient increase occurred in the frequency of reported allergic-like reactions that demonstrated a temporal pattern suggestive of the Weber effect (a transient increase in adverse event reporting that tends to peak in the 2nd year after a new agent or indication is introduced). © RSNA, 2012.

Purpose: To retrospectively determine the optimal Hounsfield unit threshold and region of interest (ROI) size required to accurately diagnose renal angiomyolipoma (AML) and differentiate it from renal cell carcinoma (RCC)., Materials and Methods: This retrospective study was institutional review board approved and HIPAA compliant, and the requirement for written informed patient consent was waived. The radiologic reports on 4502 dual-phase abdominal computed tomography (CT) examinations (nonenhanced and nephrographic phases, 5-mm collimation, 120-140 kVp, variable milliampere-second settings) performed in 2872 patients from June 2002 through October 2007 were reviewed. Solid-component masses reported as suspicious for RCC or AML were correlated with histologic and/or follow-up imaging findings. ROIs of three different sizes-tiny (8-13 mm(2)), small (19-24 mm(2)), and medium (30-35 mm(2))-were drawn in the lowest-attenuation focus on images obtained during both phases. The test characteristics (sensitivity, specificity, positive predictive value, negative predictive value, false-positive rate, false-negative rate) of multiple attenuation thresholds at each combination of ROI size and contrast enhancement phase were calculated, and receiver operating characteristic (ROC) curves were derived. Areas under the ROC curve were calculated., Results: There were 217 RCCs and 65 AMLs. With an attenuation threshold of -10 HU or lower at nonenhanced CT, RCC would be misdiagnosed as AML in 11 (5.1%) cases, one (0.5%) case, and one (0.5%) case with use of the tiny, small, and medium ROIs, respectively. With use of the tiny, small, and medium ROIs, misdiagnosis rates would be 2.3%, 0.5%, and 0.5%, respectively, at a threshold of -15 HU or lower and 1.8%, 0%, and 0%, respectively, at a threshold of -20 HU or lower. Areas under the ROC curve for the nonenhanced phase images (range, 0.874-0.889) were superior to those for the nephrographic phase images (range, 0.790-0.826)., Conclusion: Nonenhanced CT images were superior to nephrographic phase CT images for the diagnosis of AML. An attenuation threshold of -10 HU or lower with an ROI of at least 19-24 mm(2) is optimal for the diagnosis of AML. This threshold is not accurate with use of smaller (8-13-mm(2)) ROIs.

Purpose: To determine the frequency, type, and severity of breakthrough and repeat breakthrough reactions to iodinated low-osmolality contrast medium (LOCM) in patients who were premedicated with corticosteroids and antihistamines., Materials and Methods: Institutional review board approval was obtained, and informed consent was waived for this retrospective HIPAA-compliant analysis. One hundred ninety breakthrough allergic-like reactions to intravenous LOCM in 175 patients with a history of contrast medium reactions were reviewed. The repeat breakthrough reactions that resulted from 197 additional LOCM-enhanced examinations performed in 58 patients after the initial breakthrough reaction were also reviewed. The Fisher exact test was used to determine if certain risk factors were associated with an increased risk of a moderate or severe breakthrough reaction. Subgroup analysis was performed to determine if the contrast medium type, contrast medium volume, and/or time between the initial (index) and breakthrough reactions affected the breakthrough reaction severity., Results: Of 128 breakthrough reactions in which the index reaction severity was known, 103 (81%) were of a severity similar to that of the index reaction, 15 (12%) were less severe, and 10 (8%) were more severe. The severity of the breakthrough reactions in the patients with a mild index reaction was usually (in 94 [91%] of 103 reactions) mild. When the index reaction was severe, the breakthrough reaction was usually moderate or severe (in eight [42%] of 19 cases and four [67%] of six cases, respectively). The majority (174 [88%] of 197) of LOCM injections after the initial breakthrough reaction did not result in a repeat breakthrough reaction. Breakthrough reactions were significantly more likely to be moderate or severe in patients with a history of chronic oral corticosteroid use (P = .01), drug (P = .04) or severe (P < .001) allergies, or allergies to four or more allergens (P = .01)., Conclusion: Breakthrough reactions are usually similar in severity to the index reaction, and subsequent contrast medium injections usually do not induce repeat breakthrough reactions. Breakthrough reactions are more likely to be moderate or severe in patients with certain risk factors., ((c) RSNA, 2009.)

Purpose: To determine retrospectively the frequency, management, and outcomes of extravasations of intravenously injected nonionic iodinated contrast medium., Materials and Methods: Institutional review board approval was obtained, and the requirement for informed consent was waived. The study was HIPAA compliant. For 69,657 intravenous injections of nonionic iodinated contrast medium for computed tomographic examinations between January 1, 2000, and March 31, 2005, the incident reports, radiology reports, and medical records of patients in whom contrast medium extravasations occurred were reviewed. Data collected included patient age, catheter gauge, injection site, volume extravasated, patient symptoms, severity of injury, treatment, whether or not the plastic surgery service was consulted and any additional treatment that service instituted, and patient outcome., Results: Extravasations occurred in 475 (0.7%) of 69 657 patients, and follow-up information was available for 442 adults (280 women, 162 men; mean age, 57 years) and 17 children (nine girls, eight boys; mean age, 6 years). Extravasated volumes ranged from 3 to 150 mL. Symptoms usually consisted of swelling and/or pain. The plastic surgery service was consulted for 38 adults and six children and provided additional treatment in eight patients (seven adults, one child). Among adults, 432 had minimal or no adverse effects, nine had moderate adverse effects, and one had a severe complication (75 mL of contrast material extravasated into the hand, causing compartment syndrome). Only one moderate or severe complication in an adult resulted from an extravasation of less than 50 mL. Fifteen children had minimal or no adverse effects, one had moderate adverse effects, and one had a severe complication (18 mL of contrast material extravasated into the arm, causing brachial plexopathy)., Conclusion: Extravasation of nonionic iodinated contrast medium results only rarely in moderate or severe adverse effects, and these usually occur only when large volumes of contrast medium are involved.

Purpose: To retrospectively compare the effects of abdominal compression, intravenous saline hydration, and two imaging delays on both distention and opacification of the intrarenal collecting system and ureter during multi-detector row computed tomographic (CT) urography., Materials and Methods: Institutional review board approval for reviewing images and medical records of the patients was obtained; informed patient consent was not required. Excretory phase images obtained from multi-detector row CT urography in 85 patients (57 men, 28 women) were reviewed. Examinations were performed by using one of four techniques: abdominal compression and intravenous hydration with 250 mL of normal saline, compression only, intravenous hydration with saline only, and neither compression nor saline hydration. Excretory phase imaging was performed at 300 and 450 seconds for each patient. Two reviewers measured urinary tract distention on transverse images and graded opacification and image quality on volume-rendered images. Effects were compared by using statistical mixed models with repeated-measures analysis of variance., Results: Saline hydration significantly improved opacification (P = .02) and overall image quality (P < .001) of the intrarenal collecting system and proximal ureter. Delayed excretory phase image acquisition of 450 seconds significantly increased distention of the intrarenal collecting system and proximal ureter (P < .001). No significant effects involving the lower segment of the ureter were seen with any technique; however, there were fewer nonvisualized distal ureteral segments with the longer imaging delay., Conclusion: Compression does not significantly improve distention or opacification of the urinary tract. Saline hydration is effective in improving opacification of the proximal urinary tract. Longer imaging delays improve distention of the proximal urinary tract and may aid in visualization of the lower segment of the ureter., ((c) RSNA, 2005.)

Purpose: To assess the accuracy of a dedicated adrenal computed tomographic (CT) protocol., Materials and Methods: One hundred sixty-six adrenal masses were evaluated with a protocol consisting of unenhanced CT, and, for those with attenuation values greater than 10 HU, contrast material-enhanced and delayed enhanced CT. Attenuation values and enhancement washout calculations were obtained. An adenoma was diagnosed if a mass had an attenuation value of 10 HU or less at unenhanced CT or a percentage enhancement washout value of 60% or higher., Results: The final diagnosis was adenoma in 127 masses and non-adenoma in 39. Masses measuring more than 10 HU on unenhanced CT scans were confirmed at biopsy (n = 28) or were examined for stability or change in size at follow-up CT performed at a minimum interval of 6 months (n = 33). Thirty-six (92%) of 39 non-adenomas and 124 (98%) of 127 adenomas were correctly characterized. The sensitivity and specificity of this protocol were 98% and 92%, respectively. This protocol correctly characterized 160 (96%) of 166 masses., Conclusion: With a combination of unenhanced and delayed enhanced CT, nearly all adrenal masses can be correctly categorized as adenomas or non-adenomas.

Purpose: To evaluate multi-detector row computed tomographic (CT) urography for detection of urinary tract abnormalities., Materials and Methods: Sixty-five patients referred from the urology service, in whom urinary tract abnormalities were strongly suspected, underwent multi-detector row CT urography. The technique included unenhanced, nephrographic, compression, and excretory-phase images through the abdomen and pelvis. Transverse images and three-dimensional reformations were reviewed by one of two radiologists. Findings were retrospectively compared with results of urinalysis, cystoscopy and/or ureteroscopy, and/or surgery., Results: Multi-detector row CT urography depicted many clinically diagnosed urinary tract abnormalities, including 15 of 16 uroepithelial malignancies, five congenital anomalies, five urinary tract calculi, and 18 calyceal and/or papillary, 30 renal pelvic and/or ureteral, and 25 bladder abnormalities. All abnormalities were detected on transverse images. These abnormalities included diffuse urothelial wall thickening in four patients (three of whom had transitional cell carcinoma), a renal abscess, a colovesical fistula, and incidentally detected extrarenal disease (a liver mass, hepatic metastases, lymph node metastases, an aortic dissection, and a pheochromocytoma; each of these findings was seen in one patient)., Conclusion: Multi-detector row CT urography is a useful method for detecting urinary tract abnormalities.

Purpose: To determine the optimal phase for enhancement of the normal pancreas and peripancreatic vasculature and the maximal tumor-to-pancreatic parenchymal enhancement difference by using multiphase, contrast material-enhanced, multi-detector row helical computed tomography (CT)., Materials and Methods: Forty-nine patients with a normal-appearing pancreas but suspected of having pancreatic abnormality and 28 patients with proved pancreatic adenocarcinoma underwent multiphase, contrast-enhanced, multi-detector row CT during the arterial phase (AP), pancreatic parenchymal phase (PPP), and portal venous phase (PVP). Attenuation values of the normal pancreas, pancreatic adenocarcinoma, celiac and superior mesenteric arteries, and superior mesenteric and portal veins were measured during all three imaging phases. Quantitative analysis of these measurements and subjective qualitative analysis of tumor conspicuity were performed., Results: Maximal enhancement of the normal pancreatic parenchyma occurred during the PPP. Maximal tumor-to-parenchyma attenuation differences during the PPP and PVP were equivalent but greater than that during the AP. Subjective analysis revealed that tumor conspicuity during the PPP and PVP was equivalent but superior to that during the AP. Maximal arterial enhancement was seen during the PPP, and maximal venous enhancement was seen during the PVP., Conclusion: A combination of PPP and PVP imaging is sufficient for detection of pancreatic adenocarcinoma, because it provides maximal pancreatic parenchymal and peripancreatic vascular enhancement. AP imaging can be reserved for patients in whom CT angiography is required.

Purpose: To investigate the utility of computed tomographic (CT) virtual cystoscopy in the detection of bladder tumors., Materials and Methods: Twenty-six patients suspected or known to have bladder neoplasms underwent CT virtual and conventional cystoscopy. The bladder was insufflated with carbon dioxide through a Foley catheter. Helical CT of the bladder was then performed. The data were downloaded to a workstation for interactive intraluminal navigation. Two radiologists blinded to the results of conventional cystoscopy independently reviewed the transverse and virtual images, with consensus readings for cases with discrepant results., Results: Thirty-six (90%) of 40 bladder lesions proved at conventional cystoscopy were detected with a combination of transverse and virtual images. Four (10%) of 40 bladder lesions, all smaller than 5 mm, were undetected. Transverse and virtual images were complementary, since six polypoid lesions smaller than 5 mm depicted on the virtual images were not seen on the transverse images. In contrast, areas of wall thickening were more readily appreciated on transverse images. CT with patients in both supine and prone positions was necessary, since seven (19%) and five (14%) of 36 lesions were seen only on supine and prone images, respectively., Conclusion: CT virtual cystoscopy is a promising technique for use in bladder tumor detection of lesions larger than 5 mm. Optimal evaluation requires adequate bladder distention with the patient in both supine and prone positions and interpretation of both transverse and virtual images.

Purpose: To describe the radiographic features and potential causes of urethral disruption in pancreas transplant recipients., Materials and Methods: Eight episodes of urinary extravasation were depicted with retrograde urethrography in five male patients who had undergone pancreatic transplantation. The patients' medical records were reviewed to determine a cause of the extravasations., Results: Four extravasations occurred at the proximal (deep) bulbar urethra, three at the bulbomembranous junction of the urethra, and one at the distal bulbar urethra. Four of eight cases of extravasation were preceded by recent cystoscopy or placement of a Foley catheter; one case was preceded by possible urethral injury due to a fall., Conclusion: Urethral disruption occurs as a complication of pancreatic transplantation. It has so far been seen only in male patients and occurs at the bulbar urethra or bulbomembranous junction. If the treating physician is unaware of this condition, diagnosis and institution of appropriate therapy may be delayed. Recent prior urinary tract instrumentation or trauma may be predisposing factors in urinary extravasation.

Purpose: To describe positional variation in the outcome of the Whitaker test., Materials and Methods: The authors retrospectively reviewed the cases of six patients in whom the pressure gradient during Whitaker testing varied by at least 10 cm of water and changed from normal ( < or = 13 cm of water) to abnormal ( > 13 cm of water) when patients were placed in different positions., Results: Four patients had obstruction only in nonstandard positions. All had intermittent symptoms, and three had ureteral kinks at fluoroscopy. Two patients with ileal conduits had abnormal results in the standard position but normal results at repositioning related to compression of the conduits (seen as conduit distention at fluoroscopy). All six had undergone urinary tract surgery. Gradient differences with positional change ranged from 10 to > 38 cm of water., Conclusions: Whitaker testing in different positions may help identify intermittent obstructions that might otherwise go undetected or prevent inappropriate diagnosis of obstruction. Intermittent or unexplained symptoms, tortuous ureters, malpositioned kidneys, or previous surgery are indications for provocative positional testing.

Purpose: To evaluate the role of thin-section helical computed tomography (CT) performed during the corticomedullary phase (CMP) and nephrographic phase (NP) of contrast enhancement in the detection and characterization of renal masses., Materials and Methods: Renal CT scans and medical records of 33 patients were retrospectively reviewed. In all examinations, 5-mm-thick, contiguous, helical-mode scans were obtained before and 40 seconds after initiation of dynamic bolus injection of contrast material (CMP images); 5-mm-thick, contiguous, axial-mode scans were obtained after completion of CMP scanning (NP images)., Results: At review of CMP, NP, and combination images, 259, 389, and 417 lesions, respectively, were identified. The greatest difference in detection occurred in the renal medulla, with 25 lesions identified on CMP images and 111 lesions identified on NP images. False-positive results occurred when CMP images were reviewed without NP images., Conclusion: CT scans obtained only during the CMP of contrast enhancement fail to depict many renal masses that are easily seen on NP images.

Purpose: To determine whether computed tomography (CT) assessment of the proximal extent of ruptured aneurysms can help the surgeon determine whether to initially clamp the pararenal aneurysm neck or the supraceliac aorta., Materials and Methods: CT scans and medical records were reviewed and compared for 30 patients with ruptured abdominal aortic aneurysms (AAAs) who underwent immediate surgical repair., Results: For 49 of 50 vessels in 25 patients, the authors correctly predicted at CT that AAAs originated caudal to the main renal artery origins. They also predicted that nine main renal arteries in five patients originated directly from the AAAs, but this was correct in only five arteries. Suprarenal clamping was required in all five patients. Infrarenal clamps were used before reconstruction in all 12 of the patients whose AAAs appeared to originate at least 30 mm below the main renal arteries., Conclusion: CT can help predict whether an initial aortic clamp can be placed caudal to the main renal artery orifices. Its use can be predicted with 100% certainty only when an aneurysm appears to originate at least 3 cm caudal to the origin of the main renal artery.

Purpose: To assess the decisions made by uroradiologists regarding choice of type of intravenous contrast material (low-osmolar contrast media [LOCM] vs conventional ionic agents) and frequency of use of corticosteroid prophylaxis., Materials and Methods: A questionnaire was mailed to 158 members of the Society of Uroradiology. There were 108 responses received, yielding a response rate of 68%. Results from 76 represented institutions were tabulated., Results: Most respondents practice at institutions in which LOCM are used selectively rather than universally. Corticosteroid prophylaxis in patients at risk is used with similar frequency at both types of institutions. There is considerable diversity in pretreatment regimens (ie, type and dose of corticosteroid used). Although antihistamines are used by many uroradiologists (almost always in conjunction with corticosteroids), H2 receptor antagonists are used at only a few institutions., Conclusion: At institutions in which LOCM are used selectively, the majority of respondents use LOCM quite liberally, with most choosing these agents in patients at risk. Corticosteroid prophylaxis is widely used by respondents. There is much variation in the type of pretreatment regimen and its use in specific clinical settings.

To determine whether the captopril-stimulated renal vein renin ratio (CSRVRR) could enable identification of patients with hemodynamically significant renovascular lesions who would respond to revascularization, the authors measured CSRVRRs in 143 consecutive patients with hypertension who had been selected because of clinical features suggestive of renovascular hypertension. All patients underwent conventional renal arteriography. Renovascular hypertension was the final diagnosis if revascularization resulted in cure or improvement in blood pressure. Complete data were available for 133 patients. Twenty patients had renovascular hypertension; CSRVRR was greater than 1.5 in 13 of these 20 patients (sensitivity, 65%). However, it was also greater than 1.5 in 54 of the 113 patients without renovascular hypertension (false-positive rate, 47.8%). The positive predictive value of CSRVRR was 18.6%; the negative predictive value, 89.3%. It is concluded that CSRVRR is not sufficiently sensitive to enable prediction of which patients will respond to revascularization and is not specific enough to exclude patients who do not have renovascular hypertension.

The authors report four large-volume (greater than 20-mL) extravasations in adults and one intermediate-volume (18-mL) extravasation in an infant of iopamidol, a nonionic contrast medium, that occurred during dynamic enhanced computed tomography. The largest volume that extravasated (in two patients) was 150 mL. Although all five patients initially had swelling, erythema, and/or pain after extravasation, all recovered uneventfully. The authors suggest that emergent surgical drainage of all large-volume extravasations, a procedure that was recently recommended, is unnecessary. Large extravascular collections of nonionic contrast media can be well tolerated and are often resorbed without adverse sequelae.

Seventy-five patients with gastric carcinoma underwent preoperative staging with computed tomography (CT). In 14 patients, CT failed to demonstrate lymphadenopathy despite the presence of malignant lymph nodes at surgery. In 13 patients, CT demonstrated enlarged nodes, but no malignant involvement was found at surgery. Although spread to the pancreas was correctly predicted in three patients with lack of fat plane between tumor and pancreas, five patients lacking a fat plane had no invasion, whereas eight patients with an intact fat plane had invasion. Thirty-five patients (47%) were incorrectly staged with CT:23 (31%) were understaged and 12 (16%) were overstaged. CT does not accurately display the true extent of disease in patients with gastric carcinoma and therefore should not be used routinely for staging.

The choice of a contrast agent for pulmonary angiography has important implications for patient comfort, image quality, and perhaps the safety of the procedure, particularly for "high-risk" patients. In a prospective study the nonionic, low-osmolality agent iopamidol eliminated the problem of image degradation due to coughing, and patients showed excellent tolerance for it. However, pressure measurements obtained within 3-5 minutes of injection of iopamidol and diatrizoate sodium meglumine 76% showed no significant difference in the hemodynamic effects of the two contrast agents, either for normotensive or for pulmonary hypertensive patients. Contrary to a common presumption, pulmonary hypertension by itself did not appear to increase the risk of pulmonary angiography. The theoretic presumption of greater hemodynamic stability with low-osmolality contrast agents was not clinically evident in this trial with iopamidol. At present, enhanced patient comfort and improved image quality remain the only confirmed bases for choosing this contrast agent for pulmonary angiography.

Intravenous digital subtraction renal angiography (DSRA) has been compared with conventional angiography only in small, selected series of hypertensive patients. The authors prospectively examined with intravenous DSRA 94 patients at increased risk for renovascular hypertension and compared these studies with conventional angiography. A stenosis of at least one main renal artery was identified with intravenous DSRA in 22 patients and confirmed in 20 patients. No significant stenoses were seen with conventional angiography in any of the 64 patients in whom lesions were not seen with intravenous DSRA. Since inadequate DSRA studies were considered positive for renal artery stenosis, the sensitivity of intravenous DSRA was 100% (25 of 25); specificity, 93% (64 of 69); positive predictive value, 83% (25 of 30); and negative predictive value, 100% (64 of 64). The authors conclude that intravenous DSRA is a sensitive test for identifying stenosis of the main renal arteries and is appropriate to use as a screening test among patients at increased risk for renovascular hypertension.

Inflatable artificial urinary sphincters provide excellent voluntary continence. Eighty-four consecutive patients underwent implantation of artificial urinary sphincters for intractable urinary incontinence; 33 patients had 58 episodes of sphincter malfunction, and eight patients had eight complications involving a functional prosthetic sphincter. Retrospective analysis was performed to determine the value of plain radiography of the pelvis in patients with sphincter malfunction or complication. The cause of malfunction in the majority of patients was a system leak and subsequent loss of hydraulic fluid (31 occurrences; 53%). Plain radiography permitted correct identification of all instances of fluid leakage in patients with opacified prostheses. Plain radiographs were of no value in examining patients with nonopacified prostheses or the complications of cuff erosion or wound infection. Due to the low cost and noninvasive nature of plain radiography of the pelvis, we conclude that it should be used as the initial diagnostic modality in patients with previously opacified but currently dysfunctional artificial urinary sphincters.

Ultrasound scans of 51 consecutive patients with gallbladder wall thickening were reviewed, and specific sonographic features were correlated with surgical and clinical follow-up. Two patterns of thickening were identified as specific indicators of the presence or absence of acute cholecystitis. "Striated" wall thickening, consisting of several alternating, irregular, discontinuous, lucent and echogenic bands, was seen in eight of 13 patients (62%) with acute cholecystitis. This pattern was not encountered in any of the patients who did not have acute cholecystitis. Conversely, "three-layer" thickening, consisting of a single circumferential lucent zone between two relatively uniform echogenic layers, was seen in only one of 13 patients (8%) with acute cholecystitis but in 11 of 38 patients (29%) with other diagnoses. Other abnormalities, including the presence of intramural echogenic foci and wall irregularities, were more frequently seen in patients with acute cholecystitis but were not as helpful. Use of these features may suggest or help exclude a diagnosis of acute cholecystitis in those patients in whom the cause of gallbladder wall thickening is otherwise not apparent.