Understanding spatial relationships in US: a computer-based training tool that utilizes inexpensive off-the-shelf game controllers.

The authors present a simulation-based ultrasonographic (US) training tool that can help improve the understanding of spatial relationships in US. Use of a game controller to simulate a US probe allows examination of different virtual three-dimensional (3D) objects. These 3D objects are either completely artificial simple geometric objects (eg, spheres, tubes, and ellipsoids, or more complex combinations thereof) or derived from photographed gross anatomic data (eg, the Visible Human dataset [U.S. National Library of Medicine]) or clinical computed tomographic (CT) data. The virtual US probe allows infinitely variable real-time positioning of a "slice" that is displayed as a two-dimensional (2D) cross-sectional image and as part of a 3D view. Combining the 2D and 3D views helps elucidate the spatial relationships between a 3D object and derived 2D images. This training tool provides reliable real-time interactivity and is widely available and easily affordable, since it utilizes standard personal computer technology and off-the-shelf gaming hardware. For instance, it can be used at home by medical students or residents as a complement to conventional US training. In the future, this system could be adapted to support training for US-guided needle biopsy, with use of a second game controller to control the biopsy needle. Furthermore, it could be used as a more general interactive visualization tool for the evaluation of clinical 3D CT and magnetic resonance imaging data, allowing efficient and intuitive real-time creation of oblique multiplanar reformatted images.

Accuracy of plain abdominal radiographs in the detection of retained surgical needles in the peritoneal cavity.

OBJECTIVE: To determine the accuracy of plain abdominal radiographs in the detection of retained surgical needles of varying size in the peritoneal cavity. SUMMARY BACKGROUND DATA: Accidental retention of surgical foreign bodies in the peritoneal cavity is estimated to occur once in every 1000 to 1500 abdominal operations and early prevention and identification of retained foreign bodies is increasingly important because of mounting public awareness. Most of the existing literature on the imaging detection of surgical foreign bodies has focused on retained sponges, even though retained needles may account for up to 50% of such objects and the true accuracy of plain abdominal radiographs in the detection of retained needles is not well established. METHODS: Eight plain radiographs were obtained of a 41 kg pig cadaver after placement of a total of 39 surgical needles of varying size (4-77 mm in length) in a randomized selection of the 9 segments of the peritoneal cavity. Five radiologists independently reviewed the radiographs and indicated the location of all suspected retained needles. Analyses were performed using the known site and size of placed needles as the standard of reference. RESULTS: In total for all readers, 195 needles were detectable in 360 abdominal segments. The overall mean accuracy, sensitivity, and specificity for plain radiographs in the detection of retained surgical needles were 74% (267 of 360), 69% (135 of 195), and 80% (132 of 165), respectively. Sensitivity for needles 25 mm or more in length was significantly (P < 0.0001) higher than that for needles of 11 to 24 mm or 10 mm or less, with respective values of 99% (69 of 70), 84% (46 of 55), and 29% (20 of 70). Readers demonstrated moderate interobserver agreement, with a multireader kappa value of 0.60. CONCLUSIONS: Abdominal radiographs have high sensitivity and interobserver agreement in the detection of retained surgical needles over 10 mm in length, but smaller needles are detected with significantly lower sensitivity and the utility of plain abdominal radiographs in this setting is more debatable.

Pregnancy in chronic renal failure: a novel cause of theca lutein cysts at MRI.

We describe the MRI findings of bilateral ovarian theca lutein cysts in a pregnant patient with chronic renal failure. The recognition that pregnancy in chronic renal failure may result in theca lutein cysts, presumably due to excessive serum beta human chorionic gonadotropins (hCGs) secondary to impaired renal excretion, expands the differential diagnosis for this MRI appearance, in addition to the usual considerations of gestational trophoblastic disease, multiple gestation, and ovarian hyperstimulation.

CT and MRI of congenital anomalies of the seminal vesicles.

OBJECTIVE: The purpose of this article is to provide a current review of the spectrum of CT and MRI findings seen in common congenital anomalies of the seminal vesicles. CONCLUSION: CT and MRI can both accurately show renal and seminal vesicle anomalies. Seminal vesicle anomalies often occur concurrently with renal and vasal defects. MRI is a better tool for accurately defining anatomic relationships when one is planning to excise a seminal vesicle cyst or if one is considering a difficult differential diagnosis.

Magnetic resonance imaging of hepatocellular carcinoma mimicking focal nodular hyperplasia: a potential pitfall in patients with cirrhosis?

The magnetic resonance imaging findings in 2 cases of pathologically proven hepatocellular carcinoma that mimicked focal nodular hyperplasia are presented. Both cases were found in patients with cirrhosis, a condition in which focal nodular hyperplasia is unlikely to occur. Recognition that hepatocellular carcinoma may mimic focal nodular hyperplasia in patients with cirrhosis may prevent misdiagnosis and allow for earlier intervention.

Frequency and etiology of midesophageal diverticula at barium esophagography.

Midesophageal diverticula were identified at 8 of 218 (3.6%) esophagrams performed over a 3-year period in adult patients with no prior history of gastroesophageal surgery. All eight patients received a final diagnosis of esophageal dysmotility with secondary pulsion diverticula, and seven of eight (88%) patients had abnormal peristalsis noted during the esophagram. We conclude that most, if not all, midesophageal diverticula are pulsion in etiology, and the detection of a midesophageal diverticulum should prompt a careful search for underlying dysmotility.

Inferior vena cava filling defects on CT and MRI.

OBJECTIVE: The purpose of this article is to describe the appearance and causes of inferior vena cava (IVC) filling defects, how such findings may be accurately characterized, and the clinical significance of IVC filling defects. Filling defects in the IVC observed at MDCT and MRI may be a result of flow artifacts, anatomic variants, or bland or malignant thrombus. CONCLUSION: Familiarity with anatomy and flow effects is critical for distinguishing true from false filling defects in the IVC. Delayed imaging after administration of IV contrast material and dedicated MRI sequences may be helpful for further characterization of such findings. Once a true filling defect of the IVC is established, identification of the cause, whether benign or malignant, and extent will guide clinical treatment.

Minor morphologic abnormalities of adrenal glands at CT: prognostic importance in patients with lung cancer.

PURPOSE: To determine the prognostic importance of minor morphologic abnormalities of the adrenal glands at computed tomography (CT) in patients with lung cancer. MATERIALS AND METHODS: The study was approved by the committee on human research; written informed consent was not required. The authors retrospectively identified 197 patients with lung cancer who underwent serial chest or abdominal CT and did not have a focal adrenal mass at baseline CT. Two readers independently classified the morphologic features of each adrenal gland as normal, smoothly enlarged, or nodular at initial CT examination. They separately recorded the presence or absence of metastases to the adrenal glands (ie, any new focal adrenal mass) at final CT examination; a third independent reader arbitrated when interpretations were discordant (n = 11). Multivariate Cox proportional hazard models were used to assess for associations between baseline adrenal gland morphologic features and subsequent development of adrenal metastases. RESULTS: At initial CT, reader 1 classified 253 (64%), 70 (18%), and 71 (18%) of the 394 adrenal glands and reader 2 classified 258 (65%), 45 (11%), and 91 (23%) of these glands as normal, smoothly enlarged, or nodular, respectively. The readers had moderate interobserver agreement regarding the classification of adrenal gland morphologic features (kappa = 0.54). Metastases subsequently developed in 13 adrenal glands in 11 patients. Cox proportional hazard models revealed no significant association between baseline adrenal gland morphologic features and subsequent development of adrenal metastases (P = .50 and P = .20 for readers 1 and 2, respectively). CONCLUSION: In patients with lung cancer, smooth enlargement or nodularity of the adrenal glands at baseline CT is not associated with increased risk of subsequently developing adrenal metastases.

Living donor candidates for right hepatic lobe transplantation: evaluation at CT cholangiography--initial experience.

PURPOSE: To retrospectively evaluate computed tomographic (CT) cholangiography in the depiction of second-order biliary tract anatomy in living donor candidates for right hepatic lobe transplantation. MATERIALS AND METHODS: Human research committee approval was obtained, informed consent was not required, and the study was compliant with the Health Insurance Portability and Accountability Act. The authors identified all living right-lobe liver donor candidates who underwent CT cholangiography at their institution between October 2001 (when CT cholangiography was introduced at the institution) and March 2003 (n = 62). There were 41 men (mean age, 36 years; range, 18-55 years) and 21 women (mean age, 40 years; range, 22-55 years). Two readers in consensus rated quality of second-order bile duct visualization at CT cholangiography on a four-point scale (0, not seen; 3, excellent visualization) and noted the presence of variant second-order biliary tract branching anatomy. CT cholangiography findings were compared with those at surgery in subjects who underwent right hepatic lobe retrieval (n = 24). In addition, adult donors who underwent right hepatic lobe retrieval between January 2000 and March 2003 (29 men, mean age, 35 years [range, 20-52 years]; 18 women, mean age, 38 years [range, 23-54 years]) were identified. Numbers of donors who underwent intraoperative cholangiography before and after the introduction of CT cholangiography were compared by using the Fisher exact test. RESULTS: The mean second-order bile duct score at CT cholangiography was 2.9 (range, 2-3). Of 24 subjects who underwent right lobe retrieval, biliary tract anatomy determined at CT cholangiography was concordant with findings at surgery in 23 (96%). Variant second-order branching anatomy was seen in 13 subjects (54%) at surgery; one variant branch was missed at CT cholangiography. Of 47 subjects who underwent right hepatic lobe retrieval, significantly fewer subjects required conventional intraoperative cholangiography after the introduction of CT cholangiography (three of 24 subjects [12%]) than before (23 of 23 subjects; P < .0001). CONCLUSION: CT cholangiography accurately depicts biliary tract anatomy in living donor candidates for right hepatic lobe transplantation, and donors who undergo preoperative CT cholangiography are unlikely to need conventional intraoperative cholangiography.

Small hypoattenuating hepatic lesions at contrast-enhanced CT: prognostic importance in patients with breast cancer.

PURPOSE: To retrospectively determine the prognostic importance of small hypoattenuating hepatic lesions at contrast material-enhanced computed tomography (CT) in patients with breast cancer. MATERIALS AND METHODS: This retrospective study was approved by the committee on human research. Written informed consent was not required. The authors retrospectively identified 153 patients with breast cancer who underwent serial abdominal CT and who did not have definite liver metastases present at initial CT. The mean age was 56 years (age range, 27-93 years). Two readers independently recorded the presence, size, and number of small (15 mm or less in diameter) hypoattenuating hepatic lesions at initial CT. Another reader independently recorded the presence or absence of definite hepatic metastases at final CT. The association between the presence, size, and number of small hypoattenuating hepatic lesions at initial CT and the subsequent development of metastases was analyzed by using Kaplan-Meier analysis. RESULTS: One or more small hypoattenuating hepatic lesions were seen at initial CT in 54 of 153 patients (35%). After a median follow-up of 584 days (range, 16-1827 days), definite hepatic metastases developed in 43 of 153 patients (28%), including 15 of 54 patients (28%) with hypoattenuating lesions at initial CT and 28 of 99 patients (28%) without hypoattenuating lesions at initial CT. Findings from the Kaplan-Meier analysis showed no association between the presence (P = .56), size (P = .55), or number (P = .30) of small hypoattenuating hepatic lesions at initial CT and the subsequent development of hepatic metastases. CONCLUSION: In patients with breast cancer who do not have definite hepatic metastases at initial examination, there is no evidence that small hypoattenuating hepatic lesions seen at initial CT contribute to an increased risk of subsequently developing hepatic metastases.

Intrahepatic portal-to-portal venous shunts in cirrhosis: a potential mimic of hepatocellular carcinoma.

Two intrahepatic portal-to-portal venous shunts demonstrated at computed tomography (CT) and ultrasound in a 40-year-old woman with cirrhosis are described. The shunts appeared as hypervascular hepatic foci on CT, simulating multifocal hepatocellular carcinoma. Follow-up multiphase CT with multiplanar reformation and Doppler ultrasound confirmed the correct diagnosis. Recognition of intrahepatic portal-to-portal venous shunts as a rare mimic of hepatocellular carcinoma in cirrhosis should prevent misinterpretation or inappropriate management.

Computed tomography of corpus luteal cysts.

OBJECTIVE: To describe the computed tomography (CT) features of corpus luteal cysts. METHODS: We retrospectively identified 10 patients with a diagnosis of corpus luteal cysts established by ultrasound who had also undergone contemporaneous CT. A single attending radiologist, without knowledge of other clinical or radiologic findings, recorded the morphologic features of the cysts based on the CT images. RESULTS: The corpus luteal cyst seen at sonography was visible at CT in all 10 patients. All cysts were unilocular, with a mean density of 25 HU (range, 12 to 45). The mean maximum axial cyst diameter was 2.2 cm (range, 1.4 to 2.9). The mean cyst wall thickness was 3 mm (range, 2 to 4). All cyst walls were crenulated. Cyst wall enhancement was hyperdense in 6 cases, isodense in 3 cases, and hypodense in 1 case. Free fluid was seen in 9 of 10 patients. CONCLUSIONS: At CT, corpus luteal cysts are typically less than 3 cm in diameter and are characterized by a thick, crenulated, or hyperdense wall. Recognition of these CT findings should prevent misinterpretation or inappropriate management.

Biliary tract depiction in living potential liver donors: comparison of conventional MR, mangafodipir trisodium-enhanced excretory MR, and multi-detector row CT cholangiography--initial experience.

PURPOSE: To compare biliary tract depiction in living potential liver donors at conventional magnetic resonance (MR), mangafodipir trisodium-enhanced excretory MR, and multi-detector row computed tomographic (CT) cholangiography. MATERIALS AND METHODS: Eight living potential liver donors underwent iodipamide meglumine-enhanced CT cholangiography. Eight different potential liver donors then underwent conventional MR cholangiography and mangafodipir trisodium-enhanced excretory MR cholangiography. Two readers independently scored all first-, second-, and third-order biliary branches with a four-point scale from 0 (not seen) to 3 (excellent visualization). Interobserver agreement was calculated by using the weighted kappa statistic. Scores were compared between imaging modalities by using generalized estimating equations. Imaging findings of second-order biliary tract anatomy were compared with intraoperative findings for nine patients. RESULTS: Interobserver agreement for overall biliary tract visualization was good for CT, conventional MR, and excretory MR cholangiography (with weighted kappa values of 0.76, 0.66, and 0.79, respectively). The mean second-order biliary branch visualization scores for readers 1 and 2, respectively, were significantly higher at CT cholangiography (2.81 and 2.75) than at conventional MR (1.84 and 1.75, P <.001), excretory MR (2.00 and 2.06, P <.001), and combined conventional and excretory MR cholangiography (2.31 and 2.25, P <.01). At CT, conventional MR, and excretory MR cholangiography, respectively, second-order biliary branching anatomy was discernible in eight, five, and seven patients, with second-order biliary branch variants seen in three, two, and two patients. Surgical findings confirmed the pattern of second-order biliary branching seen at CT in five patients, that seen at conventional MR imaging in one patient, and that seen at excretory MR cholangiography in three patients. At surgery, one case of variant biliary anatomy was found to have been missed at CT cholangiography. CONCLUSION: In living potential liver donors, CT cholangiography enables significantly better biliary tract visualization than conventional or excretory MR cholangiography either alone or in combination.

Peritoneal calcification: causes and distinguishing features on CT.

OBJECTIVE: We undertook this study to determine the causes of peritoneal calcification seen on CT and to investigate which CT features distinguish benign from malignant peritoneal calcification. MATERIALS AND METHODS: Seventeen patients with peritoneal calcification were identified through retrospective review of reports from 74765 abdominopelvic CT examinations performed during a 7-year period. We determined the cause of peritoneal calcification by examining medical and histopathologic records. Calcification morphology was classified as nodular or sheetlike on the basis of the consensus interpretation by two independent radiologists. The radiologists also recorded the presence or absence of associated soft-tissue components or lymph node calcification. The association between the CT findings and the cause of calcification was assessed using chi-square analysis. RESULTS: Peritoneal calcification was due to peritoneal dialysis (n = 4), prior peritonitis (n = 3), cryptogenic origin (n = 1), or peritoneal spread of ovarian carcinoma (n = 9). Sheet-like calcification was more common in patients with benign calcification (seven of eight patients) than in those with malignant calcification (two of nine patients, p < 0.05). Nodal calcification was seen only in patients with malignant calcification (five of nine patients vs none of eight, p < 0.05). CONCLUSION: Common causes of peritoneal calcification are dialysis, prior peritonitis, or ovarian cancer; sheetlike calcification indicates a benign cause, whereas associated lymph node calcification strongly suggests malignancy.

Appearance and distinguishing features of retroperitoneal calcifications at computed tomography.

OBJECTIVES: To describe the appearance of retroperitoneal calcifications seen at computed tomography (CT) and to investigate which CT features distinguish benign from malignant retroperitoneal calcifications. METHODS: We identified 25 patients with retroperitoneal calcifications by retrospective review of 39,931 abdominopelvic CT scans. Etiology of retroperitoneal calcifications was determined by examination of medical and histopathological records. By consensus, 2 abdominal radiologists recorded calcification number (solitary or multiple), location (suprarenal or infrarenal), morphology (globular or nonglobular), and the presence of soft-tissue components. The association between CT findings and etiology was assessed using the Fisher exact test. RESULTS: Retroperitoneal calcifications were malignant in 15 patients and benign in 10. Solitary calcifications were seen more commonly in patients with benign disease (6 of 10 vs. 1 of 15, P < 0.01). Suprarenal calcifications were seen only in patients with malignancy (13 of 15 patients, P < 0.01). Nonglobular calcifications were seen only in patients with benign disease (6 of 10, P < 0.01). Soft-tissue components were seen more commonly in patients with malignancy (14 of 15 vs. 4 of 10; P < 0.01). CONCLUSIONS: Retroperitoneal calcifications are rarely seen at CT and may be benign or malignant in etiology. Solitary or nonglobular retroperitoneal calcifications are likely to be benign while calcifications that are multiple, globular, suprarenal, or associated with noncalcified soft-tissue components are likely to be malignant.

Distinction of renal cell carcinomas from high-attenuation renal cysts at portal venous phase contrast-enhanced CT.

PURPOSE: To determine if renal cell carcinomas can be distinguished from high-attenuation renal cysts on portal venous phase contrast material-enhanced computed tomographic (CT) scans. MATERIALS AND METHODS: Fifty-seven renal cell carcinomas and 37 high-attenuation (>20 HU) renal cysts that were at least 1 cm in diameter were retrospectively identified in 90 patients who underwent portal venous phase contrast-enhanced CT. Two independent readers recorded the CT number and degree of internal heterogeneity (uniform or mildly, moderately, or markedly heterogeneous) of all lesions. Logistic regression analysis with adjustment for the two readers was used to examine the association between clinical and CT parameters and the final diagnosis. Stepwise logistic regression analysis was used to identify independent distinguishing variables, which were then incorporated in a classification and regression tree analysis to construct the most efficient classification algorithm. RESULTS: Renal cell carcinomas were of significantly greater size (5.10 cm vs 2.84 cm, P <.001), mean attenuation (101.2 HU vs 55.3 HU, P <.001), and internal heterogeneity (P <.001) than high-attenuation renal cysts. Stepwise logistic regression showed attenuation and internal heterogeneity were both independent variables associated with final diagnosis, but lesion size was not an independent distinguishing variable after adjustment for internal heterogeneity. Classification and regression tree analysis demonstrated that an attenuation greater than 70 HU or the presence of moderate or marked internal heterogeneity was an accurate sign of renal cell carcinoma, with a sensitivity of 91% (52 of 57) for both readers and a specificity of 92% (34 of 37) for reader 1 and 84% (31 of 37) for reader 2. CONCLUSION: On portal venous phase contrast-enhanced CT scans, attenuation greater than 70 HU or moderate or marked internal heterogeneity favor a diagnosis of renal cell carcinoma over a diagnosis of high-attenuation renal cyst.

Distinguishing features of self-limiting adult small-bowel intussusception identified at CT.

PURPOSE: To determine if clinical or computed tomographic (CT) findings can be used to distinguish self-limiting cases of adult small-bowel intussusception from those requiring surgery. MATERIALS AND METHODS: Thirty-seven cases of adult small-bowel intussusception were identified by a retrospective computerized search of 69,040 abdominopelvic CT examinations performed over a 4-year period. Two independent readers recorded CT features. Clinical findings and outcomes were determined by review of all available medical records. Outcome was classified as either surgical or self-limiting. Association between predictive variables and outcome was assessed by the Fisher exact test and logistic regression models. A multivariate, stepwise, logistic regression model was used to determine the best predictors of outcome. RESULTS: Six patients (16%) underwent surgery, and all had lead-point tumors. Thirty-one patients were cared for conservatively (84%) and none required surgery at a mean follow-up of 5.2 months (range, 0-46 months). Multivariate, stepwise, logistic regression analysis showed intussusception length was the only variable that was independently predictive of outcome. All 20 patients with an intussusception length of 3.5 cm or less, as measured by either reader, had cases that were self-limiting. Seventeen patients had an intussusception length greater than 3.5 cm, as measured by either reader. Eleven patients had an intussusception that was self-limiting, and six patients had an intussusception that required surgery. CONCLUSION: Intussusception length is the main factor in distinguishing the majority of small-bowel intussusceptions detected at CT that are self-limiting from the minority that require surgery. An intussusception that is shorter than 3.5 cm is likely to be self-limiting.

Precaval right renal artery: description and embryologic origin.

OBJECTIVES: To describe our experience with precaval right renal arteries and discuss a theory of development of this unusual vascular variant. The right renal artery typically passes dorsal to the inferior vena cava and is thought to represent a consistent anatomic relationship. METHODS: Three cases of precaval renal arteries were identified during laparoscopic and endourologic procedures. The intraoperative and radiologic anatomic findings were recorded. The embryologic origins of the kidney and renal artery were reviewed to postulate a mechanism for the precaval location of a renal artery. RESULTS: In all cases, the precaval renal artery was an accessory vessel to the lower pole. Computed tomography demonstrated the location of the accessory artery ventral to the vena cava; the superior "main" renal artery was dorsal to the vena cava. In addition, bifid collecting systems (ie, pelves) were present, and the renal contours suggested nearly complete fusion of two renal moieties, with normal location and rotation of the kidney. No other cases of precaval renal arteries were recorded in urologic operative reports during the past 5 years at the University of California, San Francisco. CONCLUSIONS: The precaval renal artery is a rare but important variant of renal vascular anatomy. Several associated findings on computed tomography (bifid collecting system, enlarged kidney) may suggest its presence. The embryologic origin is likely due to the late, incomplete division of the ureteral bud during the eighth week of gestation. The renal artery to the lower pole develops and persists after the posterior cardinal vein has become the inferior vena cava but before gonadal descent.