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Biomedical subjects

Benjamin M Yeh

Publications and source records attributed to Benjamin M Yeh.

At least 19 recordsLinked to original sources
PubMed2007

Predicting biliary complications in right lobe liver transplant recipients according to distance between donor's bile duct and corresponding hepatic artery.

PURPOSE: To retrospectively determine whether biliary complications in recipients of living-donor right lobe liver grafts can be predicted at pretransplantation donor computed tomography (CT). MATERIALS AND METHODS: The human research committee approved this study. The requirement for informed consent was waived. Multi-detector row CT cholangiography and CT angiography were performed in 44 consecutive right lobe liver donors (25 men, 19 women; mean age, 37 years). When CT cholangiography in the donor demonstrated the right biliary anatomy (conventional or variant), the shortest distance between the right main (or second-order) hepatic artery and the corresponding right main (or second-order) bile duct was measured and compared with posttransplantation biliary complications in the transplant recipient by using generalized estimating equations. RESULTS: In 22 transplant recipients with one right main duct-to-common duct anastomosis (ie, conventional donor anatomy), the distance between the donor's right main bile duct and hepatic artery generally was small (mean distance, 3.8 mm; range, 1-14 mm) and unrelated (P=.46) to biliary complications (n=6). In 22 recipients who required two second-order right duct anastomoses (ie, with variant donor anatomy), the distance between the donor's second-order duct and corresponding hepatic artery was more variable (mean distance, 6.6 mm; range, 1-32.5 mm), and biliary complications were significantly more common when this distance was 10 mm or greater (in eight of 13 ducts with conventional anatomy and four of 31 ducts with variant anatomy, P<.05). CONCLUSION: Right lobe liver graft recipients who have variant right biliary anatomy and a second-order bile duct 10 mm or farther from the corresponding hepatic artery are at high risk for biliary complications, possibly because of a predisposition to ischemic injury.

Adult↗
PubMed2006

Pancreatoblastoma in an adult: case report and review of the literature.

A 50-year-old man presented with progressive gastrointestinal symptoms. An abdominal computed tomography scan demonstrated a 12 x 12-cm pancreatic mass involving the greater curvature of the stomach and multiple hypervascular hepatic metastases. An initial fine needle aspiration of the pancreatic mass was nondiagnostic, and a subsequent fine needle aspiration of a liver mass was read as metastatic acinar cell carcinoma. The patient underwent a palliative resection for tumor-associated pain and gastrointestinal hemorrhage that revealed a large pancreatic tumor invading through the full thickness of the colon at the splenic flexure and adherent to the posterior gastric wall. The pathology from the distal pancreatectomy, splenectomy, partial gastrectomy, partial colectomy, and cholecystectomy unexpectedly supported a diagnosis of pancreatoblastoma with evidence for squamoid corpuscles as well as areas of acinar formation. Despite multiple chemotherapy regimens, the patient's disease continued to progress in the liver and the lungs. During the course of his therapy, the patient's serum alpha-fetoprotein levels and serum lipase levels rose concurrently, suggesting tumor-associated production of both of these factors. Seventeen months after the diagnosis of metastatic pancreatoblastoma, the patient died from his disease. Our case illustrates the fact that pancreatoblastomas are extremely difficult to diagnosis preoperatively. In addition, our case demonstrates that pancreatoblastomas can be alpha-fetoprotein producing, hormone producing, and enzyme producing when it occurs in adults.

Abdominal Pain↗
PubMed2006

Gallstone detection at CT in vitro: effect of peak voltage setting.

This study was a retrospective single-institutional study approved by the Committee on Human Research and was HIPAA compliant. A waiver for informed consent was granted. The purpose of the study was to evaluate the effect of four peak voltage settings on the in vitro conspicuity of gallstones in an anthropomorphic phantom at computed tomography (CT). An anthropomorphic phantom was scanned with (n = 86) or without (n = 85) gallstones at CT by using 80, 100, 120, and 140 kVp. The sensitivity for gallstone detection was significantly higher at 140 kVp (86% [74 of 86] for reader 1 and 81% [70 of 86] for reader 2) than at lower voltage settings (up to 67% [58 of 86] for reader 1 and 63% [54 of 86] for reader 2, P < .05 for each reader), regardless of gallstone size (<1.0 cm vs > or =1.0 cm in diameter, P < .05 for each reader). CT attenuation measurements were not useful for determination of gallstone composition. Abdominal CT performed at 140 kVp may be useful when gallstone disease is of clinical concern.

Adult↗
PubMed2006

Has the time arrived to image placental perfusion?

Taillieu et al have shown that it is possible to noninvasively measure the placental blood flow, fractional volume of the maternal vascular placental compartment, and rate of transfer of contrast material between the maternal and fetal circulation in gravid mice through the use of dynamic contrast-enhanced MR imaging. Clearly, much work lies ahead before functional evaluation of the placenta becomes a clinical reality, but contrast-enhanced imaging shows promise for functional evaluation of placental disease.

Animals↗
PubMed2006

CT and MRI of adnexal masses in patients with primary nonovarian malignancy.

OBJECTIVE: The purpose of this pictorial essay is to review the differential considerations when an adnexal mass is detected on CT or MRI in a patient with a primary nonovarian malignancy. CONCLUSION: Such adnexal masses may be metastases to the ovaries, primary ovarian malignancy, or incidental benign disorders. Solid masses are more likely metastases, but metastases can be predominantly cystic and primary ovarian cancers can be solid. MRI may help characterize incidental benign entities such as endometriosis, fibroma, and peritoneal inclusion cysts.

Adnexal Diseases↗
PubMed2005

Dynamic contrast-enhanced magnetic resonance imaging as a pharmacodynamic measure of response after acute dosing of AG-013736, an oral angiogenesis inhibitor, in patients with advanced solid tumors: results from a phase I study.

PURPOSE: Identifying suitable markers of biologic activity is important when assessing novel compounds such as angiogenesis inhibitors to optimize the dose and schedule of therapy. Here we present the pharmacodynamic response to acute dosing of AG-013736 measured by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). PATIENTS AND METHODS: Thirty-six patients with advanced solid tumors were treated with various doses of AG-013736. In addition to standard measures of objective disease response and pharmacokinetic analysis, DCE-MRI scans were acquired at baseline and repeated at cycle 1--day 2 after the scheduled morning dose of the AG-013736 in 26 patients. Indicators of a vascular response, such as the volume transfer constant (K(trans)) and initial area under the curve (IAUC), were calculated to assess the effect of treatment on tumor vascular function. RESULTS: Evaluable vascular response data were obtained in 17 (65%) of 26 patients. A linear correlation was found in which the percentage change from baseline to day 2 in K(trans) and IAUC was inversely proportional to AG-013736 exposure. Using a conservative a priori assumption that a > or = 50% decrease in K(trans) was indicative of an objective vascular response, a 50% decrease in K(trans) was achieved and corresponded to a plasma AUC(0-24) of > 200 ng . h/mL. CONCLUSION: A sufficient decrease in tumor vascular parameters was observed at a dose chosen for additional phase II testing by conventional toxicity criteria. In addition, the day 2 vascular response measured using DCE-MRI seems to be a useful indicator of drug pharmacology, and additional research is needed to determine if it is a suitable marker for predicting clinical activity.

Administration, Oral↗
PubMed2005

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.

Adolescent↗
PubMed2005

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.

Adult↗
PubMed2005

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.

Adrenal Gland Neoplasms↗
PubMed2005

Accuracy of liver fat quantification at MR imaging: comparison of out-of-phase gradient-echo and fat-saturated fast spin-echo techniques--initial experience.

PURPOSE: To retrospectively determine the relative accuracy of liver fat quantification with out-of-phase gradient-echo magnetic resonance (MR) imaging and fat-saturated fast spin-echo MR imaging in patients with and without cirrhosis, with histologic analysis as the reference standard. MATERIALS AND METHODS: Committee on Human Research approval was obtained. Patient consent was not required. Data collection ended before HIPAA regulations were implemented, but patient anonymity was maintained. Twenty-seven patients, 16 with cirrhosis, were retrospectively identified who underwent MR imaging before histopathologic evaluation of liver fat at biopsy or surgery. The patient population consisted of 15 male and 12 female patients (mean age, 55 years; range, 16-75 years). One radiologist blinded to the histopathologic results recorded mean signal intensity derived from three regions of interest placed in the right and left lobes of the liver on three sections and signal intensity of the spleen from one region of interest within the same section. Liver fat was quantified with the relative loss of signal intensity on out-of-phase images compared with that on in-phase T1-weighted gradient-echo images and with relative loss of signal intensity on T2-weighted fast spin-echo MR images obtained with fat saturation compared with those obtained without fat saturation. Hotelling t test was used to compare correlation coefficients between relative signal intensity differences and histopathologically determined percentage of fat. RESULTS: In patients without cirrhosis, liver fat quantification with fat-saturated fast spin-echo MR imaging was significantly better than it was with out-of-phase gradient-echo MR imaging (r = 0.92 vs 0.69, P < .01). In patients with cirrhosis, liver fat quantification was correlated only with fat-saturated fast spin-echo MR imaging (r = 0.76, P < .01); the relative signal intensity loss on out-of-phase gradient-echo MR images was not correlated with histopathologically determined percentage of fat (r = 0.25, P = .36). CONCLUSION: Preliminary results suggest liver fat may be more accurately quantified with fat-saturated fast spin-echo MR imaging than with out-of-phase gradient-echo MR imaging, especially in patients with cirrhosis.

Adolescent↗
PubMed2005

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.

Adolescent↗
PubMed2005

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.

Artifacts↗
PubMed2004

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.

Adult↗