Biomedical subjects

Benjamin M Yeh

Publications and source records attributed to Benjamin M Yeh.

47 records · Page 3Linked to original sources

PubMedDate not supplied

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.

Adult↗

PubMedDate not supplied

Frequency of hepatic contour abnormalities and signs of portal hypertension at CT in patients receiving chemotherapy for breast cancer metastatic to the liver.

PURPOSE: This study aimed to determine the frequency of hepatic contour abnormalities and signs of portal hypertension at serial CT in patients receiving chemotherapy for breast cancer metastatic to the liver. MATERIALS AND METHODS: We retrospectively identified 91 women with breast cancer metastatic to the liver who received chemotherapy and underwent serial CT at our institution between 1998 and 2002. Two readers independently categorized hepatic contour abnormalities on the final CT examination as none, limited retraction, widespread retraction, or diffuse nodularity. Readers also recorded the development of hepatic atrophy or enlargement, ascites, portosystemic collateral veins, and splenomegaly. Interpretative discrepancies were resolved by consensus. Portal hypertension was defined as the presence of at least two of the following CT signs: simple ascites, portosystemic collateral veins, and splenomegaly. RESULTS: After a median follow-up interval of 15 months (range, 1-46), hepatic contour abnormalities were seen in 68 of 91 patients (75%) and consisted of limited retraction (n = 42), widespread retraction (n = 10), or diffuse nodularity (n = 16). Portal hypertension was found in 1 of 23 patients without contour abnormalities, in 1 of 42 patients with limited retraction, in none of 10 patients with widespread retraction, and in 6 of 16 patients with diffuse nodularity (P < .01). CONCLUSION: Hepatic contour abnormalities commonly develop at serial CT in patients undergoing chemotherapy for breast cancer metastatic to the liver and may be accompanied by signs of portal hypertension; the latter are particularly, but not exclusively, associated with the development of diffuse hepatic nodularity.

Adult↗

PubMedDate not supplied

Dendritic iodinated contrast agents with PEG-cores for CT imaging: synthesis and preliminary characterization.

The purpose of this study was to design, synthesize, and initially characterize a representative set of novel constructs for large-molecular radiographic/computed tomography (CT) contrast agents, intended for a primarily intravascular distribution. A new assembly of well-known and biocompatible components consists of paired, symmetrical dendritic polylysines initiated from both ends of a poly(ethylene glycol) (PEG) core, yielding an array of multiple free amino groups to which were conjugated highly soluble and stable triiodophthalamide ("triiodo") moieties. An array of six dendritic contrast agents was synthesized originally, using three different PEG cores (3, 6, 12 kDa) with t-Boc lysine-generated dendrimer "amplifiers" (from three to five generations) containing 16 to 64 amino groups for conjugation with reactive triiodo moieties. A clinically used, nonionic, small molecular CT contrast agent, iobitridol, was derivatized via a hydroxyl protection/deprotection strategy, introducing a new carboxyl group available for conjugation to the lysine amino groups of dendrimers. Final products were purified by size exclusion chromatography and characterized by NMR, UV, HPLC, and elemental analysis. Preliminary evaluations were conducted for physicochemical characterization and in vivo CT contrast enhancement in a rat model. All six iodinated PEG-core dendrimer conjugates were synthesized in good yields, with a high degree of size monodispersity, large apparent molecular weight, favored physicochemical properties. A representative compound, PEG12000-carbamate-Gen4-IOB conjugate, 27% (w%) rich in iodine, demonstrated a desirable strong and persistent intravascular enhancement with a monoexponential blood half-life of approximately 35 min assayed by dynamic CT imaging and also showed high water solubility (>550 mg/mL at 25 degrees C), large apparent molecular size (comparable to a 143-kDa protein), high hydrophilicity (butanol-water partition coefficient 0.015), and stability to autoclaving conditions. This study showed the synthetic feasibility, desired basic characteristics, and potential utility for CT contrast enhancement achieved with a new type of iodinated, large-molecular PEG-core dendritic construct. Further development of this class of macromolecular contrast agents will be required to define the optimal formulation, pharmacology, safety profile, and the full range of diagnostic applications including tumor microvascular quantitative characterization by CT imaging.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

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.

Adult↗

PubMedDate not supplied

Computed tomography and magnetic resonance imaging of inferior vena caval thrombus associated with metastasis to the kidney.

The computed tomography and magnetic resonance imaging findings in 2 cases of inferior vena caval thrombus associated with metastases to the kidney are presented. In both cases, the radiologic findings were suggestive of renal cell carcinoma. Recognition that metastases to the kidney can be associated with inferior vena caval thrombus broadens the differential diagnosis in a patient with a renal mass, an inferior vena caval filling defect, and a known primary malignancy, potentially altering the diagnostic approach.

Adenocarcinoma↗

PubMedDate not supplied

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.

Adolescent↗

PubMedDate not supplied

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.

Adult↗

PubMedDate not supplied

Atypical cases of gallstone ileus evaluated with multidetector computed tomography.

OBJECTIVE: To describe the multidetector computed tomography (CT) findings in 3 patients with atypical gallstone ileus. METHODS: We retrospectively evaluated computed radiography and CT images from three cases of surgically proven gallstone ileus. Two radiologists evaluated by consensus all images for the presence of ectopic gallstone, small bowel obstruction, intrahepatic pneumobilia, cholecystic pneumobilia. One author recorded whether diagnosis of gallstone ileus was made prospectively on radiologic reports and correlated findings to pathology. RESULTS: All cases of gallstone ileus were atypical in that one patient had porcelain gallbladder, one had recurrent pyogenic cholangitis, and one was only 35 years of age. Prospective clinical diagnosis of gallstone ileus was made in only 1 patient at computed radiography and all 3 patients at CT. Retrospectively, small bowel obstruction and cholecystic pneumobilia were identified retrospectively in all 3 patients at both computed radiography and MDCT, and an ectopic gallstone, intrahepatic pneumobilia, and choledochoduodenal fistula was seen in 2, 1, and 0 patients at computed radiography and 3, 2, and 3 patients at CT respectively. CONCLUSION: Multidetector CT is an accurate means to diagnose gallstone ileus, even in patients with atypical features. In particular, multidetector CT is useful for identifying the ectopic gallstone at the transition point between dilated and decompressed bowel.

Adult↗

PubMedDate not supplied

Magnetic resonance imaging of ovarian cancer arising in endometriomas.

The magnetic resonance imaging (MRI) findings in 2 cases of ovarian cancer arising in an endometrioma are presented. In both cases, the cancer was evident as an enhancing mass within a blood-filled adnexal cyst. The MRI findings of an enhancing mass within a blood-filled adnexal cyst should prompt consideration of ovarian cancer arising in an endometrioma, facilitating recognition of a superimposed malignancy and potentially allowing for earlier and more efficacious treatment.

Adenocarcinoma, Clear Cell↗

PubMedDate not supplied

Growth rate of hepatocellular carcinoma: evaluation with serial computed tomography or magnetic resonance imaging.

OBJECTIVE: To evaluate the growth rate of untreated hepatocellular carcinoma (HCC) by calculating tumor volume doubling time (TVDT) on serial computed tomography (CT) or magnetic resonance imaging (MRI) and to predict TVDT based on initial tumor size. METHODS: Sixteen untreated HCCs in 11 patients with cirrhosis who underwent serial CT or MRI at our institution were retrospectively identified. Two independent readers recorded bidimensional measurements for all tumors, which were used to determine tumor volume (TV). Growth rate was expressed as TVDT. A mathematic model was used to predict TVDT based on baseline tumor size. RESULTS: Mean baseline and follow-up TVs were 10.5 cm3 (range: 0.7-243.6 cm3) and 22.0 cm3 (range: 2.5-870.8 cm3), respectively. Mean duration of follow-up was 176 days (range: 76-472 days). Mean TVDT was 127 days (95% confidence interval: 80, 203; range: 17.5-541.4 days). Expected TVDT could be expressed as TVDT = 114 x (baseline volume)0.14 (P < 0.002). CONCLUSION: The results of this study suggest a preferred interval follow-up of approximately 4.5 months (127 days) for HCC screening. Small HCCs show a tendency toward faster growth and may require shorter follow-up to demonstrate progression.

Adult↗

PubMedDate not supplied

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.

Aged↗