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.

Determinants of second-order bile duct visualization at CT cholangiography in potential living liver donors.

OBJECTIVE: The purpose of this article is to investigate the determinants of second-order bile duct visualization at CT cholangiography in living potential liver donors. MATERIALS AND METHODS: We retrospectively identified 143 potential living liver donors (83 men and 60 women; mean age, 37 years) evaluated with CT cholangiography, which included a slow infusion of iodipamide meglumine with CT acquisition 15 minutes after biliary contrast agent administration. Two readers independently scored the visualization of the second-order bile duct branches on a previously established 4-point scale (0 = not seen, 1 = faintly seen, 2 = well seen, and 3 = excellent visualization). Multivariate analysis was used to investigate the correlation between visualization scores and potential determinants of second-order bile duct opacification, specifically age, body mass index, creatinine level, total and direct bilirubin levels, alkaline phosphatase level, aspartate aminotransferase level, alanine aminotransferase level, patient maximum linear width, CT noise, and hepatosplenic attenuation difference at unenhanced CT. RESULTS: The mean (± SD) second-order bile duct visualization scores were 2.35 ± 0.66 and 2.55 ± 0.60 for readers 1 and 2, respectively. In the multivariate analysis, the only independent predictors of reduced second-order bile duct visualization were higher alkaline phosphatase level (p = 0.01) and higher CT noise (p = 0.02). CONCLUSION: Higher serum alkaline phosphatase level and higher CT noise in potential living liver donors indicate a higher risk of poor second-order bile duct visualization at CT cholangiography.

Evaluation of potential outcome predictors in type II Endoleak: a retrospective study with CT angiography feature analysis.

OBJECTIVE: The purpose of this study is to investigate which CT features of type II endoleaks following abdominal aortic aneurysm (AAA) endoluminal stent-graft repair can be used to predict clinical outcome. MATERIALS AND METHODS: We retrospectively identified 59 patients with type II endoleak after endovascular repair of an AAA with CT of the abdomen and pelvis. Patients were stratified into two groups: those who did (n = 23) and those who did not (n = 35) require reintervention. CT characteristics of type II endoleaks were recorded and correlated with the clinical outcome. RESULTS: The CT features showing the strongest association with the clinical outcome were the transverse diameter of the endoleak cavity (mean, 1.13 cm in the nonreintervention group vs 1.85 cm in the reintervention group; p = 0.007) and the maximum diameter of the vessel communicating with the endoleak (0.34 vs 0.40 cm; p = 0.046). The transverse diameter of the endoleak cavity on arterial phase imaging had the greatest predictive capability, with an area under the receiver operating characteristic curve of 0.74. A transverse diameter greater than 1.42 cm had a positive predictive value of 0.71 and a negative predictive value of 0.82. The anteroposterior diameter, location, and heterogeneity of the endoleak cavity and the number of patent communicating vessels did not correlate well with clinical outcome. The correlation between endoleak cavity measurements and clinical outcome was independent of the aneurysm size. CONCLUSION: There are identifiable CT features associated with the clinical outcome of patients with type II endoleak that have moderate predictive capabilities.

Physiology of renal medullary tip hyperattenuation at unenhanced CT: urinary specific gravity and the NaCl concentration gradient.

PURPOSE: To retrospectively investigate the physiology of renal medullary tip hyperattenuation at unenhanced computed tomography (CT). MATERIALS AND METHODS: This retrospective single-institution study was IRB approved and HIPAA compliant. Informed consent was waived. One hundred consecutive patients (53 women, mean age, 52 years; 47 men, mean age, 48 years; P = .39) without and 34 (11 women, mean age, 49 years; 23 men, mean age, 45 years; P = .54) with unilateral ureteral obstruction underwent contemporaneous urinalysis and unenhanced CT. At CT, bladder urine attenuation was measured and two readers recorded the presence of renal medullary tip hyperattenuation. For obstructed kidneys (n = 34), renal pelvic urine attenuation was also recorded. The presence of medullary tip hyperattenuation was correlated with urinary specific gravity. To investigate the physiologic basis of medullary tip hyperattenuation, attenuations for NaCl and urea phantoms (range, 0-2000 mosm/kg) were recorded and correlated to solute concentrations by using linear regression. RESULTS: Patients with renal medullary tip hyperattenuation seen at CT had higher mean urinary specific gravity (1.023 and 1.022 for readers 1 and 2, respectively) than those without (1.015 and 1.016, respectively, both P < .05). The specific gravity correlated with higher urine attenuation (r = 0.40, P < .001). For the 34 patients with unilateral urinary obstruction, medullary tip hyperattenuation was less commonly seen in obstructed (two kidneys each for both readers) than nonobstructed (11 and 15 kidneys, respectively, both P < .005) kidneys and mean urine attenuation was lower in the obstructed renal pelvis (7.4 HU) than in the bladder (11.4 HU) (P < .005). Phantoms showed a 3.6-HU increase per 100-mosm/kg increase in NaCl concentration (r = 0.99, P < .001) but no change in attenuation with different urea concentrations. CONCLUSION: Renal medullary tip hyperattenuation at unenhanced CT reflects increased urinary specific gravity, likely related to high medullary tip NaCl concentrations.

CT cholangiography in potential liver donors: effect of premedication with intravenous morphine on biliary caliber and visualization.

PURPOSE: To retrospectively determine whether premedication with intravenously administered morphine improves bile duct caliber and visualization in potential liver donors undergoing computed tomographic (CT) cholangiography. MATERIALS AND METHODS: This was a retrospective single institution study approved by the institutional review board and compliant with requirements of the HIPAA. Multidetector CT cholangiography was performed after slow infusion of 20 mL of iodipamide meglumine 52% diluted in 80 mL of normal saline in 143 consecutive potential liver donors (81 men and 62 women; mean age, 37 years); 43 received premedication with intravenous morphine sulfate (0.04 mg per kilogram of body weight) and 100 did not. Two independent readers recorded common bile duct diameter and area on axial CT images. Readers also scored bile duct visualization, including all second-order biliary branches, on a four-point scale (0, not seen; 3, excellent visualization). RESULTS: For scans obtained without and those obtained with morphine, there was no significant difference in the mean common bile duct diameter (4.1 vs 4.3 mm for reader 1 and 4.4 vs 4.6 mm for reader 2, respectively; P > .39 for both readers), in common bile duct area (20.7 vs 21.5 mm(2), for reader 1 and 21.3 vs 20.2 mm(2) for reader 2, respectively, P > .60 for both), or in second-order bile duct visualization score (2.34 vs 2.36 for reader 1 and 2.58 vs 2.50 for reader 2, respectively; P > .5 for both). CONCLUSION: The results suggest that premedication with intravenous morphine prior to CT cholangiography in potential liver donors does not increase bile duct caliber or improve biliary visualization.

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.

Recording, editing, archiving, and distributing radiology lectures: a streamlined approach.

Recent advances in digital recording technology have simplified the recording of audio, video, and image information from didactic radiology conferences. Recording lectures in a suitable digital format has several advantages, including the ability to edit lecture content, combine lectures conducted at different times and places, store media digitally, and broadcast conferences electronically over the Internet. An inexpensive, commercially available conversion device was developed that allows straightforward capture and compression of multimedia audiovisual information, thus facilitating the use of this information by the conference presenter as well as the end user. A converter is connected to a personal computer (PC) by means of standard connections, and editing and compression of digital media are performed on the PC prior to their distribution and archiving. The result is a high-quality, highly compressed file that can be played back from any PC and from many portable video devices. This approach represents a simple and cost-effective means of creating and maintaining a library of didactic lectures for students and trainees in radiology.

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.

Renegotiating expertise: an examination of PACS and the challenges to radiology using a medical anthropologic approach.

PURPOSE: The aim of this study was to examine how the adoption of PACS has affected the professional relationships among radiologists and referring providers and to evaluate the effect of PACS on perceptions of radiologists' roles in patient care. METHODS: A medical anthropologic approach was used to assess the impact of PACS among radiologists and a community of clinical subspecialists at a large academic medical center (n = 40). Data collection techniques included 3 months of ethnographic participant observation during the routine medical practice of study participants as well as semistructured interviews and archival research. These data were then analyzed to identify behavioral and narrative patterns and themes among the study populations. RESULTS: The difficulty of establishing and maintaining relationships of trust between referring providers and radiologists due to the drop in post-PACS reading room visits emerged as a major source of concern for study participants. By interacting primarily over the phone or at weekly conferences, radiologists felt that they had fewer opportunities to build personal relationships with other clinicians. Meanwhile, the specialist referring providers stated they generally consulted only radiologists with whom they had established personal relationships and otherwise preferred to interpret their patients' images themselves. CONCLUSIONS: Generating and sustaining relationships of trust and effective communication are vital for radiologists to communicate their expertise in medical imaging to referring providers. Because PACS have caused a reduction in referring provider visits to the reading room, radiologists must seek out new opportunities to form personal relationships with other physicians.

Comparison of traditional methods with 3D computer models in the instruction of hepatobiliary anatomy.

This study was designed to determine whether an interactive three-dimensional presentation depicting liver and biliary anatomy is more effective for teaching medical students than a traditional textbook format presentation of the same material. Forty-six medical students volunteered for participation in this study. Baseline demographic information, spatial ability, and knowledge of relevant anatomy were measured. Participants were randomized into two groups and presented with a computer-based interactive learning module comprised of animations and still images to highlight various anatomical structures (3D group), or a computer-based text document containing the same images and text without animation or interactive features (2D group). Following each teaching module, students completed a satisfaction survey and nine-item anatomic knowledge post-test. The 3D group scored higher on the post-test than the 2D group, with a mean score of 74% and 64%, respectively; however, when baseline differences in pretest scores were accounted for, this difference was not statistically significant (P = 0.33). Spatial ability did not statistically significantly correlate with post-test scores for the 3D group or the 2D group. In the post-test satisfaction survey the 3D group expressed a statistically significantly higher overall satisfaction rating compared to students in the 2D control group (4.5 versus 3.7 out of 5, P = 0.02). While the interactive 3D multimedia module received higher satisfaction ratings from students, it neither enhanced nor inhibited learning of complex hepatobiliary anatomy compared to an informationally equivalent traditional textbook style approach. .

Evaluation of diffuse liver steatosis by ultrasound, computed tomography, and magnetic resonance imaging: which modality is best?

PURPOSE: To compare ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) determination of diffuse liver steatosis. MATERIALS AND METHODS: Quantification of liver steatosis on ultrasound, CT, and MRI was correlated with histopathology in 67 patients. RESULTS: Opposed-phase MRI demonstrated the highest correlation with steatosis (0.68 and 0.69, P<.01; intraclass correlation coefficient, 0.93). Spearman's correlation (and intraclass correlation) coefficients were lowest for ultrasound [0.54, 0.33 (0.40)] and enhanced CT [0.33, 0.39 (0.97)]. CONCLUSION: Opposed-phase MRI demonstrated best overall performance for determining steatosis.

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.

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.

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.

Risk of injury to adjacent organs with lower-pole fluoroscopically guided percutaneous nephrostomy: evaluation with prone, supine, and multiplanar reformatted CT.

PURPOSE: To assess the risk of injury to organs near the kidney during lower-pole fluoroscopically guided percutaneous nephrostomy by evaluation of prone, supine, and multiplanar reformatted computed tomography (CT). MATERIALS AND METHODS: Eighty-three patients who underwent prone and supine CT examinations were identified retrospectively. The expected path of nephrostomy tube placement to the lower-pole calyx was simulated on prone and supine axial images and multiplanar CT reformations. Intervening organs along this path were considered at risk for injury and were recorded for each kidney (N = 166). RESULTS: The risk of organ injury as determined on multiplanar reformatted prone images (n = 5) and supine images (n = 0) was significantly less (P < .05) than determined on axial prone images (n = 25) or supine images (n = 10). The colon was the only organ identified to be at risk for injury during the simulated lower-pole percutaneous nephrostomy placement; spleen and liver were not seen along the nephrostomy path on axial or multiplanar reformatted images. CONCLUSION: Lower-pole fluoroscopically guided percutaneous nephrostomy carries a low risk of visceral injury, and the risk of injury is overestimated by evaluation of axial CT images alone compared with oblique parasagittal reformations.

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.

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.

Concordance of second-order portal venous and biliary tract anatomies on MDCT angiography and MDCT cholangiography.

OBJECTIVE: We sought to investigate the concordance between second-order portal venous and biliary tract anatomies using MDCT angiography and MDCT cholangiography. MATERIALS AND METHODS: We retrospectively identified 56 living related potential liver donors who underwent both MDCT angiography and MDCT cholangiography. Two reviewers independently rated axial images and 3D reconstructions of MDCT angiograms and cholangiograms as diagnostic or nondiagnostic with respect to depiction of second-order portal venous and biliary tract anatomies. In images rated as diagnostic, second-order portal venous and biliary tract anatomies were categorized as conventional or variant. The concordance between portal venous and biliary tract anatomies was analyzed using McNemar exact chi-square test. RESULTS: All examinations were diagnostic. Second-order portal venous variants were seen in 10 (18%) and biliary branch variants were seen in 23 (41%) of the 56 patients. Patients with variant portal venous anatomy (6/10, 60%) were more likely to have variant biliary tract anatomy than patients with conventional portal venous anatomy (17/46, 37%; p < 0.01). The sensitivity of variant portal venous anatomy as a marker for variant biliary anatomy was 26% (6/23 patients). CONCLUSION: Concordance between second-order portal venous and biliary tract anatomies is statistically significant. However, in our series, a number of patients with conventional portal venous anatomy had variant biliary anatomy; therefore, the finding of conventional portal venous anatomy does not obviate preoperative biliary tract imaging in patients before liver donation.

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.