MR imaging in the characterization of small renal masses.

OBJECTIVE: The aim of our study was to evaluate the effectiveness of MR imaging for the characterization of small (<2 cm) renal lesions described as indeterminate on prior US or CT. MATERIALS AND METHODS: Sixty-three small renal masses in 51 patients considered indeterminate on prior ultrasound or CT scans were included in the study. A retrospective evaluation of the examinations was performed independently by two body magnetic resonance imaging (MRI) radiologists who were unaware of the final diagnosis. A 3-point confidence scale (1: benign, 2: indeterminate, and 3: malignant) was established to determine the level of suspicion for malignancy. Interobserver agreement was determined with a weighted kappa statistic. The diagnosis was verified by imaging follow-up of at least 24 months (mean 60 months) in 53 lesions and by pathology in 10 lesions. RESULTS: MRI detected all eight malignancies in the series. There were eight malignant lesions and two benign lesions among those with pathologic follow-up. No interval growth or evidence of malignancy in the remaining 53 lesions was found for a minimum of 24 months by repeat imaging. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI for differentiating benign from malignant small renal lesions were 100% (62.9-100%, 95% CI), 94.5% (84.9-98.8%, 95% CI), 72.7% (39.1-93.6%, 95% CI), and 100% (93.1-100%, 95% CI), respectively. The kappa value for interobserver agreement was 0.77 (95% CI 0.59-0.96, p-value <0.001). CONCLUSION: MR imaging is an effective method for characterizing small (<2 cm) renal masses found to be indeterminate by US or CT.

Radiologic evaluation of incidentally discovered adrenal masses.

The increasing use of cross-sectional imaging has led to an increase in the incidental discovery of adrenal masses (adrenal incidentalomas). Although most of these lesions are benign, they often present a diagnostic dilemma. Before creating a management plan, the physician should determine if the lesion is benign or malignant and if the lesion is functioning or nonfunctioning. Incidentally discovered adrenal masses usually are benign adenomas; however, myelolipomas, cysts, hemorrhage, pheochromocytomas, metastases, and adrenocortical carcinomas are also possible. Unenhanced computed tomography and chemical shift magnetic resonance imaging can characterize most adenomas because the lesions have high lipid content. Contrast-enhanced computed tomography can further characterize the adenomas because of the washout characteristics with iodinated intravenous contrast media. Fluorodeoxyglucose- positron emission tomography can be helpful in characterizing some lesions, and biopsy is rarely required. This article summarizes the American College of Radiology Appropriateness Criteria for the use of imaging modalities and biopsy to characterize incidentally discovered adrenal masses.

MR Imaging of hepatocellular carcinoma in the cirrhotic liver: challenges and controversies.

The incidence of hepatocellular carcinoma (HCC) is expected to increase in the next 2 decades, largely due to hepatitis C infection and secondary cirrhosis. HCC is being detected at an earlier stage owing to the implementation of screening programs. Biopsy is no longer required prior to treatment, and diagnosis of HCC is heavily dependent on imaging characteristics. The most recent recommendations by the American Association for the Study of Liver Diseases (AASLD) state that a diagnosis of HCC can be made if a mass larger than 2 cm shows typical features of HCC (hypervascularity in the arterial phase and washout in the venous phase) at contrast material-enhanced computed tomography or magnetic resonance (MR) imaging or if a mass measuring 1-2 cm shows these features at both modalities. There is an ever-increasing demand on radiologists to detect smaller tumors, when curative therapies are most effective. However, the major difficulty in imaging cirrhosis is the characterization of hypervascular nodules smaller than 2 cm, which often have nonspecific imaging characteristics. The authors present a review of the MR imaging and pathologic features of regenerative nodules and dysplastic nodules and focus on HCC in the cirrhotic liver, with particular reference to small tumors and lesions that may mimic HCC. The authors also review the sensitivity of MR imaging for the detection of these tumors and discuss the staging of HCC and the treatment options in the context of the guidelines of the AASLD and the imaging criteria required by the United Network for Organ Sharing for transplantation. MR findings following ablation and chemoembolization are also reviewed.

Vascular malformation and hemangiomatosis syndromes: spectrum of imaging manifestations.

OBJECTIVE: The purpose of this review is to describe the role of imaging and associated findings in the diagnosis of blue rubber bleb nevus syndrome, Proteus syndrome, Klippel-Trénaunay syndrome, and Kasabach-Merritt syndrome. CONCLUSION: Blue rubber bleb nevus, Proteus, Klippel-Trénaunay, and Kasabach-Merritt syndromes are a diverse group of vascular malformation and hemangiomatosis syndromes. Both cutaneous and visceral vascular lesions are associated with these disorders. Accurate diagnosis of these syndromes is important because they can be associated with serious complications, including life-threatening hemorrhage.

Renal trauma: imaging evaluation and implications for clinical management.

Severe renal injuries are usually associated with multisystem injuries, may require interventional radiology to control hemorrhage and improve the chances for renal salvage, and are more likely to fail nonoperative management. However, most renal injuries are mild in severity and successfully managed conservatively. The AAST classification is the most widely used system to describe renal injuries and carries management and prognostic implications. CT with intravenous contrast is the imaging test of choice to assess for renal injuries. Contrast extravasation indicating active bleeding should be mentioned as its presence is predictive for failure of nonoperative management. Radiologists play a critical role in identifying renal injuries and should make every effort to describe renal injuries according to the AAST grading scheme to better inform the surgeon's management decisions.

Interventional therapies for hepatocellular carcinoma.

Hepatocellular carcinoma is the third most common cause of cancer-related death. In the past few years, staging systems have been developed that enable patients to be stratified into treatment algorithms in a multidisciplinary setting. Several of these treatments involve minimally invasive image-guided therapy that can be performed by radiologists.

Temporary placement of stent grafts in postsurgical benign biliary strictures: a single center experience.

OBJECTIVE: To evaluate the effect of temporary stent graft placement in the treatment of benign anastomotic biliary strictures. MATERIALS AND METHODS: Nine patients, five women and four men, 22-64 years old (mean, 47.5 years), with chronic benign biliary anastomotic strictures, refractory to repeated balloon dilations, were treated by prolonged, temporary placement of stent-grafts. Four patients had strictures following a liver transplantation; three of them in bilio-enteric anastomoses and one in a choledocho-choledochostomy. Four of the other five patients had strictures at bilio-enteric anastomoses, which developed after complications following laparoscopic cholecystectomies and in one after a Whipple procedure for duodenal carcinoma. In eight patients, balloon-expandable stent-grafts were placed and one patient was treated by insertion of a self-expanding stent-graft. RESULTS: In the transplant group, treatment of patients with bilio-enteric anastomoses was unsuccessful (mean stent duration, 30 days). The patient treated for stenosis in the choledocho-choledochostomy responded well to consecutive self-expanding stent-graft placement (total placement duration, 112 days). All patients with bilio-enteric anastomoses in the non-transplant group were treated successfully with stent-grafts (mean placement duration, 37 days). CONCLUSION: Treatment of benign biliary strictures with temporary placement of stent-grafts has a positive effect, but is less successful in patients with strictures developed following a liver transplant.

CT appearances following laparoscopic partial nephrectomy for renal cell carcinoma using a rolled cellulose bolster.

PURPOSE: To describe the evolving computed tomography (CT) appearances of a cellulose surgical bolster used as a hemostatic agent in patients who undergo laparoscopic partial nephrectomy for renal cell carcinoma. MATERIALS AND METHODS: We retrospectively reviewed the follow-up CT studies of 33 patients with stage T1N0M0 renal carcinoma who underwent laparoscopic partial nephrectomy using a rolled, oxidized, regenerated cellulose sheet sutured in place as a bolster in the parenchymal defect. Thirteen patients undergoing laparoscopic partial nephrectomy without the use of a bolster were also evaluated to differentiate imaging features. RESULTS: The bolster-related masses were significantly larger than those seen in the non-bolster patients. There was a decrease in size of the post-operative bolster-related mass with time. The bolster shape evolved with time, initially appearing oval, and becoming irregular with decreasing size. Equivocal increase in attenuation of 10-20 HU was seen in 6 patients. Increase in attenuation of greater than 20 HU was seen in 3 patients. There was no evidence of tumor recurrence in any of the patients. Invagination of fat was seen in two bolster-related masses at 18 months or greater. CONCLUSIONS: Cellulose bolster has a variable appearance on follow-up CT exams. Evolutionary features include reduction in bolster size and shape with time leading finally to non-visualization. Bolster enhancement can mimic abscesses and tumor recurrence.

Computed tomography urography: trends in positivity rates over time.

PURPOSE: To investigate changes in usage of computed tomography urography (CTU), indications for CTU, and rates of positive findings over time. METHODS: Retrospective review of data from April 2000 to December 2005 assessed rates of overall positive findings, rates of suspected transitional cell carcinomas (TCCs), benign genitourinary (GU), and significant non-GU findings. Data were analyzed based on specialty of ordering physicians and on requisition indications. RESULTS: One thousand two hundred seventy-one patients had 1746 CTUs, including 952 men (1259 studies) and 319 women (487 studies) with mean age of 61 years. Computed tomography urographies increased from 265 in 2001 to 443 in 2004. Eighty-nine percent were ordered by urologists, 4% by oncologists, 1% by emergency physicians, and 6% by other specialties. Sixty-two percent of first-time studies were ordered for possible GU malignancy, 24% for hematuria, and 14% for other reasons. Eight hundred sixty-one examinations (49%) showed significant findings. The rate of all positive examinations, analyzed in 6-month periods, varied from 37% to 54%, but no time trend was identified. First-time patient examinations had positive examinations in 46% to 62% of cases. Similarly, no trends were found for examinations interpreted as possible TCC (17%-32%), renal stones (9%-18%), renal masses (1%-6%), causes of hematuria (15%-26%), and acute non-GU findings (2%-9%). The rate of positive findings by ordering specialty varied minimally from 49% to 53%. No change occurred in the proportions of indications for CTU over time. CONCLUSIONS: In 5 years, the number of CTU examinations per year increased 1.5-fold. The rate of CTU findings positive for suspected TCC, stones, and other causes of hematuria showed no decline or increase. If precautions are taken regarding proper indications for CTU, the overall rates of positive findings may not substantially change over time, thereby only submitting high-risk patients to this examination.