Mass-like peripheral zone enhancement on CT is predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer.

PURPOSE: To determine whether focal peripheral zone enhancement on routine venous-phase CT is predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer. MATERIALS AND METHODS: IRB approval was obtained and informed consent waived for this HIPAA-compliant retrospective study. Forty-three patients with higher-grade prostate cancer (≥Gleason 4 + 3) and 96 with histology-confirmed lower-grade (≤Gleason 3 + 4 [n = 47]) or absent (n = 49) prostate cancer imaged with venous-phase CT comprised the study population. CT images were reviewed by ten blinded radiologists (5 attendings, 5 residents) who scored peripheral zone enhancement on a scale of 1 (benign) to 5 (malignant). Mass-like peripheral zone enhancement was considered malignant. Likelihood ratios (LR) and specificities were calculated. Multivariate conditional logistic regression analyses were conducted. RESULTS: Scores of "5" were strongly predictive of higher-grade prostate cancer (pooled LR+ 9.6 [95% CI 5.8-15.8]) with rare false positives (pooled specificity: 0.98 [942/960, 95% CI 0.98-0.99]; all 10 readers had specificity ≥95%). Attending scores of "5" were more predictive than resident scores of "5" (LR+: 14.7 [95% CI 5.8-37.2] vs. 7.6 [95% CI 4.2-13.7]) with similar specificity (0.99 [475/480, 95% CI 0.98-1.00] vs. 0.97 [467/480, 95% CI 0.96-0.99]). Significant predictors of an assigned score of "5" included presence of a peripheral zone mass (p < 0.0001), larger size (p < 0.0001), and less reader experience (p = 0.0008). Significant predictors of higher-grade prostate cancer included presence of a peripheral zone mass (p = 0.0002) and larger size (p < 0.0001). CONCLUSION: Focal mass-like peripheral zone enhancement on routine venous-phase CT is specific and predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer.

Computed tomography and magnetic resonance features of renal Ewing sarcoma.

Ewing sarcoma (ES) is a rare malignant tumor that primarily involves long and flat bones but can develop in almost any bone or soft tissue. ES accounts for 2.3-3.5% of tumors in patients under the age of 19, and is rarely found in the adult population. Sarcomas, in general, account for less than 1% of tumors in adults. Several reports of renal ES have been described in the pediatric population, but only a few cases have been described in the adult population. To the best of our knowledge, fewer than 10 cases of renal Ewing sarcoma in adults have been described in the English literature. None of these cases described the computed tomography (CT) and magnetic resonance imaging (MRI) features. We report a case of a 46-year-old woman, including CT and MRI characteristics.

Unknown ESUR cases 2004.

The authors present 14 cases from the film interpretation session of the 11th annual meeting of the European Society of Urogenital Radiology presented in September, 2004. The cases demonstrate the imaging findings, differential diagnoses, and clinical relevance of a wide variety of genitourinary tract diseases. The cases include examples of benign and malignant urinary tract neoplasms, inflammatory processes, vascular diseases, traumatic injuries, and congenital anomalies.

Multislice CT urography: state of the art.

Recent improvements in helical CT hardware and software have provided imagers with the tools to obtain an increasingly large number of very thin axial images. As a result, a number of new applications for multislice CT have recently been developed, one of which is CT urography. The motivation for performing CT urography is the desire to create a single imaging test that can completely assess the kidneys and urinary tract for urolithiasis, renal masses and mucosal abnormalities of the renal collecting system, ureters and bladder. Although the preferred technique for performing multislice CT urography has not yet been determined and results are preliminary, early indications suggest that this examination can detect even subtle benign and malignant urothelial abnormalities and that it has the potential to completely replace excretory urography within the next several years. An important limitation of multislice CT urography is increased patient radiation exposure encountered when some of the more thorough recommended techniques are utilized.

Effectiveness of abdominal compression during helical renal CT.

RATIONALE AND OBJECTIVES: The authors performed this study to assess the effect of abdominal compression on opacification and distention of the proximal renal collecting system during helical computed tomography (CT). MATERIALS AND METHODS: Abdominal compression was applied during helical CT in 31 patients who were scanned 150 and 300 seconds after initiating a dynamic bolus injection of contrast material. Two reviewers assessed renal collecting system opacification and measured the maximal short-axis diameter of the collecting system at three locations: the upper pole, the lower pole, and the proximal ureter. A similar evaluation was performed in a control group of 29 patients who underwent CT without compression at 300 seconds after initiating the injection of contrast material. RESULTS: Both reviewers noted collecting system opacification at all locations in 52 of 56 noncompressed collecting systems scanned at 300 seconds, 57 of 59 compressed collecting systems scanned at 300 seconds, but only 26 of 59 compressed collecting systems scanned at 150 seconds. Measured collecting system distention was statistically significantly greater at 300 seconds in patents who received compression than in patients who did not (P = .0013). For patients who received compression, measured collecting system distention was statistically significantly greater on scans obtained at 300 seconds than on scans obtained at 150 seconds (P = .0001). CONCLUSION: Abdominal compression during renal helical CT produces a detectable increase in renal collecting system distention. In patients who receive compression, scanning at 300 seconds rather than at 150 seconds results in greater collecting system distention and more consistent opacification.

Assessment of the clinical utility of the rim and comet-tail signs in differentiating ureteral stones from phleboliths.

OBJECTIVE: This study was designed to assess interobserver variability in identifying the rim and comet-tail signs and to determine the clinical utility of these signs in determining whether or not the calcifications with which they are associated represent ureteral calculi. MATERIALS AND METHODS: Two radiologists and a radiology resident, unaware of the final diagnosis, reviewed preselected helical CT images from renal stone examinations in patients with 65 indeterminate pelvic calcifications. Assessment of calcifications for rim or comet-tail signs was performed independently of an assessment for the following five secondary signs of urinary tract obstruction: caliectasis, pelviectasis, ureterectasis, perinephric stranding, and renal enlargement. Agreement in identifying rim and comet-tail signs was assessed by obtaining kappa statistics. The utility the of rim or comet-tail signs in determining whether ureterolithiasis was present in patients in whom perinephric stranding and ureterectasis were present or absent was determined. The frequency with which one or more of each of the five assessed secondary signs was identified ipsilateral to a calcification having rim or comet-tail signs was also tabulated. RESULTS: Kappa values for interobserver agreement ranged from 0.49 to 0.73. In only one patient was a rim sign detected in the absence of ureterectasis and perinephric stranding. Reviewers identified at least three of the five assessed secondary signs ipsilateral to calcifications showing a rim sign in all but one patient (by each radiologist) and four patients (by the resident). When three or more secondary signs of obstruction were seen ipsilateral to a calcification having a comet-tail sign, in all but one instance, this was because the calcification was a ureteral calculus or because there was a separate ipsilateral ureteral calculus. CONCLUSION: In many instances, observers did not agree about whether the rim and comet-tail signs were present. The rim sign was observed in the absence of any secondary signs of urinary tract obstruction in only one (1.5%) of the 65 patients in our series (95% confidence interval, 0-5.3%). The comet-tail sign, when accompanied by secondary signs of obstruction, should indicate that an ipsilateral ureteral stone is present and not the reverse.

Multi--detector row helical CT of the pancreas: effect of contrast-enhanced multiphasic imaging on enhancement of the pancreas, peripancreatic vasculature, and pancreatic adenocarcinoma.

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.

Bladder tumor detection at virtual cystoscopy.

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.

Correlation between radiology resident rotation performance and examination scores.

RATIONALE AND OBJECTIVES: The authors' purpose was to determine whether there is a relationship between subjective assessment of radiology resident performance on individual rotations and objective assessment of radiology resident performance on the American College of Radiology (ACR) in-training and American Board of Radiology (ABR) written examinations. MATERIALS AND METHODS: Records of 81 radiology residents completing their residency between 1991 and 2000 were reviewed. Mean scores from all rotation evaluation forms obtained during the study period were calculated for each residency year. The means of the overall raw scores and percentiles obtained on the annual ACR in-training examinations during the first 3 years of residency and of the written portion of the ABR examination taken during the 4th year of residency were also determined. Rotation evaluation scores were then compared to examination scores obtained during the same year of residency, and correlation coefficients were obtained. RESULTS: In the 2nd, 3rd, and 4th years of radiology residency, there is positive correlation between rotation evaluation scores and overall scores from the corresponding ACR in-training examination and written portion of the ABR examination taken during the same year. In contrast, in the 1st year of residency, resident rotation evaluation scores do not correlate with ACR in-training examination scores. CONCLUSION: Residents who are perceived as doing well on their rotations after the 1st year of residency are more likely to do well on standardized written examinations.

Delayed enhanced CT of lipid-poor adrenal adenomas.

OBJECTIVE: Although representing a minority of adrenal adenomas, the lipid-poor variety cannot be accurately identified on unenhanced CT or chemical shift MR imaging. We compared the delayed contrast-enhanced CT features of lipid-poor adenomas with those of lipid-rich adenomas and of adrenal nonadenomas to determine whether there were differences in the washout features between these groups of lesions. SUBJECTS AND METHODS: Eighteen proven lipid-poor adenomas, 56 lipid-rich adenomas, and 40 adrenal nonadenomas underwent CT before, immediately after, and 15 min delay after IV contrast injection. Region-of-interest measurements were made of all adrenal lesions at the three time points. The degree of enhancement, enhancement washout, percentage enhancement washout, and relative percentage enhancement washout were calculated for each adrenal mass. Pooled data were analyzed statistically. Optimal threshold values for diagnosing adrenal adenomas were also determined. RESULTS: The mean CT attenuation of lipid-poor adenomas was significantly higher than that of lipid-rich adenomas at all three phases but not significantly different from that of nonadenomas. The mean percentage enhancement washout on images obtained 15 min after administration of contrast material was similar for lipid-rich and lipid-poor adenomas but was significantly higher than that of nonadenomas. The mean relative percentage enhancement washout was significantly different among all three groups. CONCLUSION: Lipid-poor adenomas cannot be differentiated from adrenal nonadenomas on the basis of a single mean attenuation value. However, lipid-poor adrenal adenomas show enhancement and enhancement washout features nearly identical to lipid-rich adenomas and can be distinguished from nonadenomas on the basis of a percentage washout threshold value of 60% and a relative percentage washout of 40%.

How well does applicant rank order predict subsequent performance during radiology residency?

RATIONALE AND OBJECTIVES: Residency selection committees expend substantial time and resources on assessing the quality of residency applicants to derive an appropriate rank order for the National Residency Matching Program. The authors determined whether there is a relationship between the rank number or rank percentile of applicants selected for a residency training program and subsequent radiology residency performance. MATERIALS AND METHODS: Records of radiology residents completing their residency between 1991 and 1998 were reviewed. Available rank numbers and rank percentiles for each resident were compared with subsequent performance, as assessed subjectively by 4th-year radiology rotation evaluation forms and retrospective recall of four senior faculty members and objectively by numerical and percentile scores on the written portion of the American Board of Radiology (ABR) examinations. Correlation coefficients were obtained for each comparison. RESULTS: Rank number and rank percentile were not significantly correlated with 4th-year resident rotation evaluations or ABR written examination scores or percentiles. A small correlation existed between rank order and retrospective evaluation of resident performance by the four senior faculty. CONCLUSION: Applicant rank number and rank percentile do not correlate with subsequent radiology residency performance as assessed on rotation evaluation forms or the ABR written examinations.

Sensitivity of CT scout radiography and abdominal radiography for revealing ureteral calculi on helical CT: implications for radiologic follow-up.

OBJECTIVE: We compared the sensitivity of CT scout radiography with that of abdominal radiography in revealing ureteral calculi on unenhanced helical CT. MATERIALS AND METHODS: Over a 6-month period, patients presenting to the emergency department with acute flank pain were examined with standard abdominal radiography and unenhanced helical CT, which included CT scout radiography. In 60 patients in whom a diagnosis of ureteral calculus was made, CT scout radiographs and abdominal radiographs were examined by two interpreters who assessed whether stones could be visualized. All CT scout radiographs were viewed on a workstation using optimized window settings. RESULTS: CT scout radiography and abdominal radiography revealed 28 (47%) and 36 (60%) of 60 ureteral calculi, respectively. All ureteral calculi that appeared on CT scout radiography also appeared on abdominal radiography. However, eight calculi that were visible on abdominal radiography were not visible on CT scout radiography. CT scout radiography and abdominal radiography revealed 28% and 46% of 39 calculi less than or equal to 3 mm in diameter, respectively. For 21 calculi larger than 3 mm, the sensitivity of CT scout radiography and abdominal radiography was 81% and 86%, respectively. CONCLUSION: Abdominal radiography is more sensitive than CT scout radiography in revealing ureteral calculi; however, some calculi revealed on unenhanced helical CT cannot be seen on either abdominal radiography or CT scout radiography. Ureteral calculi not visible on either study can only be followed, when necessary, with unenhanced helical CT.

Comparison of nephrographic with excretory phase helical computed tomography for detecting and characterizing renal masses.

OBJECTIVE: A retrospective study was performed to compare nephrographic phase (NP) with excretory phase (EP) renal helical computed tomographic (CT) images with respect to detection of renal masses 10 mm or more in diameter, and reviewer confidence in mass characterization. METHODS: Two reviewers evaluated 39 renal helical CT examinations. All masses measuring 10 mm or more in maximal diameter were classified as simple cysts, complex cysts, solid lesions, or indeterminate lesions. Reviewers graded their confidence in the characterization of the masses and decided whether the NP or EP contrast-enhanced images were superior. RESULTS: The 2 reviewers confidently characterized 71 (reviewer 1) and 65 (reviewer 2) of 72 detected masses 10 mm or more in diameter on NP images and 70 (reviewer 1) and 67 (reviewer 2) of 71 detected masses on EP images. There was strong agreement between the 2 sets of images in respect to the characterization of renal masses (kappa = 1.00 and 0.86). Only one mass (a focus of acute pyelonephritis) was not detected by either reviewer on EP images. Collecting system artifact degraded the quality of the EP image in images from only 1 patient. CONCLUSION: Although EP images are often aesthetically inferior to NP images, use of EP images results in a similar rate of detection and confidence in characterization of renal masses measuring 10 mm or more in diameter.

Utility of routine trauma CT in the detection of bladder rupture.

RATIONALE AND OBJECTIVES: The purpose of this study was to determine the frequency with which routine computed tomography (CT) fails to depict bladder rupture, the potential utility of delayed CT scans, and whether these findings might be useful in determining which patients may require subsequent cystography. MATERIALS AND METHODS: Cystograms and abdominal and pelvic CT scans of 54 patients with blunt trauma and in whom bladder rupture was clinically suspected were retrospectively reviewed. Blind readings of CT scans were performed by two genitourinary radiologists. Cystograms were used as the standard. RESULTS: Cystograms depicted bladder rupture in 10 patients. On CT scans, extravesical fluid was depicted in all three patients with intraperitoneal bladder rupture (although only a small amount of pelvic intraperitoneal fluid was present in two of these patients), in all seven patients with extraperitoneal bladder rupture, and in 32 of the 44 patients without bladder injury. Contrast material had been excreted into the bladder at the time of the initial or delayed CT in eight patients with bladder rupture; however, extravasation was identified in only four of the eight. In two of the four patients without extravasation, the bladder was distended at the time of CT. No bladder injuries were found in the 12 patients in whom pelvic fluid was not identified on CT scans. CONCLUSION: The absence of pelvic fluid on a trauma CT scan indicates that bladder rupture is unlikely. Even when a partially opacified bladder is passively distended, bladder injury may be present despite the absence of contrast material extravasation.

CT of recurrent retroperitoneal sarcomas.

OBJECTIVE: We reviewed the medical records and CT scans of 33 patients with recurrent retroperitoneal sarcomas to determine the patterns of recurrent disease. MATERIALS AND METHODS: We reviewed the medical records and CT examinations obtained at the time the recurrence was diagnosed and tabulated data for all patients. Data for patients with high-grade malignancies were compared with those of patients with low-grade malignancies to determine whether there were differences in the interval between initial tumor resection and recurrence. We also compared CT appearances to determine patterns of recurrent disease. RESULTS: Twenty-five of 33 recurrences were detected within 2 years of initial surgery. Only 16 patients had symptoms, and when present, most symptoms were nonspecific. In 28 (85%) patients, recurrent tumor was in the abdomen at the time of diagnosis. In nine patients, the largest detectable abdominal tumor was less than 5 cm in diameter. Interval to recurrence was similar for patients with low- and high-grade tumors. Although the CT appearance was similar for both grades, distant metastases were identified only in patients with high-grade malignancies. CONCLUSION: Primary retroperitoneal malignancies frequently recur within 2 years of initial surgical resection. For asymptomatic patients, diagnosis is typically made during routine follow-up CT. Most patients have abdominal recurrences that may be small when first detected.

Different phases of renal enhancement: role in detecting and characterizing renal masses during helical CT.

Although helical CT offers greater flexibility in data acquisition and reconstruction than does conventional axial CT, new opportunities for error must be understood so that optimal protocols are used that minimize the likelihood of misdiagnosis. Most nonrenal abdominal helical CT scans are obtained late in the corticomedullary phase of renal enhancement because of the preferable enhancement of other parenchymal organs. CT evaluation of the kidneys during the corticomedullary phase or at an intermediate phase between the corticomedullary and nephrographic phases has significant limitations. Therefore, dedicated renal CT performed for the detection of suspected renal masses or for the characterization of known renal masses must include images obtained during later phases of enhancement (i.e., nephrographic or excretory phase). Nephrographic or excretory phase images appear to be similar to one another but superior to corticomedullary phase images in the ability to both detect and characterize renal masses. Corticomedullary phase images should always be obtained when information about the renal vasculature is desired or when there is a possibility that a detected renal mass may represent an aneurysm or an arteriovenous malformation or fistula. Optimal technique of helical CT for staging renal cancers may require use of both corticomedullary and nephrographic or excretory phase images, although work in this area is still preliminary.

Orthotopic neobladder reconstruction: findings on excretory urography and CT.

OBJECTIVE: The excretory urographic and CT appearance of orthotopic ileal neobladder reconstruction after cystectomy and its complications are described. MATERIALS AND METHODS: We retrospectively reviewed the excretory urograms and CT scans of 32 patients (29 men and three women, 35-76 years old) with transitional cell carcinoma of the bladder who underwent orthotopic neobladder reconstruction with anastomosis to the native urethra after cystectomy. The radiologic review consisted of 25 excretory urograms in 20 patients and 37 CT scans in 21 patients. RESULTS: On excretory urography, the afferent segment of the neobladder was identified as a contrast-filled structure in all 20 patients, and was located in the right lower quadrant in 18 (90%). On CT, the afferent segment and the neobladder were identified in all 21 patients. Delayed imaging performed after initial scanning in 12 (57%) of 21 patients was helpful for revealing detailed anatomy such as the ureteral-afferent limb anastomoses. Complications occurred in two patients and were caused by a lymphocele in one and a urine leak from the neobladder in the other. In six other patients we found evidence of recurrent or metastatic tumor or both: two had local pelvic recurrence and pelvic nodal metastases, two other patients had metastatic nodal disease, one patient had a malignant distal ureteral stricture, and the sixth patient had distant osseous metastases. CONCLUSION: Orthotopic neobladder reconstruction after cystectomy has a characteristic appearance on both excretory urography and CT. Knowledge of this appearance and the altered anatomy is useful to recognize complications and tumor recurrence. Delayed images during excretory urography and CT are useful to define the ureteral-afferent limb anastomosis with the neobladder and also to differentiate between postoperative collections.

Occurrence of adverse reactions to gadolinium-based contrast material and management of patients at increased risk: a survey of the American Society of Neuroradiology Fellowship Directors.

RATIONALE AND OBJECTIVES: The authors attempted to determine the frequency and severity of adverse reactions to gadolinium-based magnetic resonance (MR) contrast agents and to identify strategies for management of patients at increased risk. MATERIALS AND METHODS: American Society of Neuroradiology program directors were surveyed about adverse reactions at their institutions to gadolinium-based contrast agents, the contrast agents responsible, and the management of patients with allergy-like reactions to iodinated or gadolinium-based agents who required MR contrast agent administration. RESULTS: Fifty-three (50.5%) surveys were received from 105 centers. Of 687,255 gadopentetate dimeglumine injections, 314 (0.046%) nonallergic reactions and 107 (0.016%) mild, 28 (0.004%) moderate, and five (0.001%) severe allergy-like reactions occurred. Of 74,275 gadodiamide injections, 11 (0.015%) nonallergic and 12 (0.016%) mild allergy-like reactions occurred. Of 64,005 gadoteridol administrations, 171 (0.267%) nonallergic reactions and 49 (0.077%) mild, 29 (0.047%) moderate, and 11 (0.017%) severe allergy-like reactions occurred. Twenty-six departments took no precautions for patients with previous allergy-like reactions to iodinated contrast material. Nineteen did not premedicate patients who previously had reactions to gadolinium-based agents before repeat administration of MR contrast agents. CONCLUSION: Although MR contrast agents are safe, adverse reactions occur. Many centers have not adopted policies for the OFF

Local reactions after injection of iodinated contrast material: detection, management, and outcome.

RATIONALE AND OBJECTIVES: The authors assessed the frequency, sequelae, and risk factors of extravasation of intravenously administered iodinated contrast media. MATERIALS AND METHODS: All patients with local reactions after intravenous injection of contrast media between November 1994 and December 1996 were studied. Comparison was made with data obtained from a control group of 100 patients with no local reactions who underwent contrast material-enhanced computed tomography (CT). RESULTS: Local reactions were reported in 56 (0.25%) of 22,254 patients who received intravenous injections of iodinated contrast media. Fifty-one patients experienced extravasation, and five patients experienced local irritation in the absence of clinically detectable extravasation. Extravasation occurred during CT (n = 46), urography (n = 4), and venography (n = 1). Contrast material was nonionic in 37 cases and conventional ionic in 14 cases of extravasation. Extravasated volumes exceeded 30 mL in 22 patients and 100 mL in six patients. Forty-five (80%) of 56 patients with local reactions had complete resolution of symptoms within 24 hours. Only four patients had symptoms for more than 48 hours. No surgery was required. Compared with the control group, patients with extravasation were significantly more likely to have been injected with small-bore catheters (21 or 22 gauge) and to have been injected at low or high rates. CONCLUSION: Symptoms of contrast medium extravasation usually resolve quickly. In patients with extravasation, injections are more likely to have been performed with techniques that vary from normal practice.