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Biomedical subjects

F T Lee

Publications and source records attributed to F T Lee.

At least 55 records · Page 3Linked to original sources
PubMed1998

Doppler sonography in testicular and scrotal imaging.

The primary role of Doppler ultrasound of the acute testicle and scrotum is for the diagnosis of spermatic cord torsion or epididymitis. The utility of Doppler in other conditions such as testicular neoplasm is limited, and in general does not increase diagnostic specificity. The application of color Doppler imaging and power Doppler imaging increases sensitivity for the detection of orchitis and testicular neoplasms in which the gray scale findings may be subtle. Power Doppler imaging is more sensitive for the identification of slowly flowing blood than color Doppler imaging. As a result, power Doppler imaging may be particularly helpful for the diagnosis or exclusion of spermatic cord torsion as a cause of acute scrotal pain in the prepubescent male.

Journal Article↗
PubMed1998

Rapid in vivo measurement of single-kidney extraction fraction and glomerular filtration rate with MR imaging.

PURPOSE: To compare the accuracy of a noninvasive magnetic resonance (MR) imaging method to rapidly determine single-kidney glomerular filtration rate (GFR) relative to findings with an accepted standard of reference. MATERIALS AND METHODS: Simultaneous inulin and MR imaging measurements of renal excretory function were performed in six small swine. Renal extraction fraction of gadopentetate dimeglumine was determined with T1 measurements of flowing blood in the renal vein and in a systemic vessel 10-300 minutes after administration. These data were correlated with standard inulin-derived measurements of single-kidney GFR obtained during the same intervals as the MR imaging measurements. Gradient-echo (GRE) and echo-planar imaging were investigated for in vivo measurement of extraction fraction. RESULTS: The MR imaging-derived measurements of extraction fraction and single-kidney GFR were not significantly different from the inulin-determined measures (P > .18). The MR imaging extraction fraction and single-kidney GFR measurements correlated with inulin-derived measurements of the same parameters (r = .74 to .89, P < .0007). CONCLUSION: T1 measurement methods with GRE and echo-planar imaging are acceptable techniques with which to measure renal excretory function in a rapid and noninvasive manner in this model. Rapid measurements of single-kidney GFR should enable studies of the response of renal hemodynamics to pharmaceutical manipulation.

Animals↗
PubMed1998

Hepatic cryoablation: US monitoring of extent of necrosis in normal pig liver.

PURPOSE: To determine the accuracy of ultrasonography (US) for prediction of hepatic tissue necrosis after cryoablation in normal pig liver. MATERIALS AND METHODS: Five normal pig livers were treated with cryoablation monitored with US. After a single freeze cycle at 50% flow capacity, the widest diameter of the cryolesion was identified and marked with wire placement (22 wires in five lesions). Livers were removed 24 hours later, and wire tracks were marked with India ink. Livers were sectioned, and the distance was measured between wire tracks and tissue necrosis caused by freezing. RESULTS: The mean volume of areas of tissue necrosis was 11.6 cm3 +/- 4.0, the mean diameter was 2.9 cm +/- 1.0, and the mean maximum diameter was 2.9 cm +/- 0.7. The mean distance between the edge of necrosis and the wire track was 1.1 mm +/- 1.4. By excluding one outlier (6.5 mm), the mean distance from the ice ball to the necrotic area was 0.8 mm +/- 0.8. Uniform necrosis of hepatic parenchyma within the cryolesion was confirmed. CONCLUSION: US can be used to predict reliably the size of the necrotic area after hepatic cryoablation in normal pig liver. Knowledge of a small but consistent underestimation of tissue necrosis is important when planning cryoablation.

Animals↗
PubMed1998

Minimally invasive alternatives to traditional operative hepatic cryoablation: works in progress.

Primary and secondary malignant disease of the liver remains a major health problem in the United States and abroad. It is estimated that over 130,000 new cases and 55,000 deaths will result from colorectal carcinoma in 1997. In this same year, 13,600 new cases and 12,400 deaths are also expected to result from primary hepatic tumors. Worldwide, hepatocellular carcinoma results in approximately 250,000 deaths yearly.

Journal Article↗
PubMed1998

Sonography of testicular tumors and tumor-like conditions: a radiologic-pathologic correlation.

Malignant testicular tumors are an important clinical problem, and ultrasound is the most frequently ordered imaging modality once a palpable scrotal mass is discovered. Numerous articles discussing the role of ultrasound in the evaluation of testicular pathology have confirmed the value of preoperative imaging. This article presents a review of imaging literature regarding testicular neoplasms, with an emphasis on correlation of gross and microscopic tumor pathology and imaging findings. Also included are sections on anatomy, epidemiology, histogenesis, and tumor markers.

Adult↗
PubMed1997

Kinetic analysis of the interaction between the monoclonal antibody A33 and its colonic epithelial antigen by the use of an optical biosensor. A comparison of immobilisation strategies.

The interaction between the humanised A33 monoclonal antibody and the corresponding F(ab)'2 or Fab' fragments with the colonic epithelial A33 antigen, purified by micropreparative HPLC from membrane extracts of the colonic carcinoma cell line LIM 1215, has been studied with the BIAcore 2000 biosensor using surface plasmon resonance detection. The surface orientation of immobilised antibody and the Fab' fragment onto the biosensor surface was controlled using alternative immobilisation chemistries. This resulted in significantly higher molar binding activities compared with the conventional N-hydroxysuccinimide (NHS)/N-ethyl-N'-dimethylaminopropylcarbodiimide (EDC) chemistry. This increase in signal resulted in a concomitant increase in sensitivity of detection, which facilitates analysis of low levels of A33 antigen. The apparent association rate (ka) and dissociation rate (kd) constants obtained with the different immobilisation chemistries were determined. These analyses showed that the kinetic constants obtained for the IgG were not significantly affected by the method of immobilisation. F(ab)'2 and Fab' fragments immobilised using NHS/EDC chemistry showed significantly lower apparent affinity. By contrast the use of the thiol coupling chemistry with the Fab' fragment gave a five fold increase in observed KA, resulting in a similar affinity to that observed with the intact IgG molecule.

Antibodies, Monoclonal↗
PubMed1997

Perivascular and intralesional tissue necrosis after hepatic cryoablation: results in a porcine model.

BACKGROUND: Cryosurgical ablation of malignant hepatic tumors is being increasingly used for definitive treatment of metastatic colorectal and primary hepatic tumors. The lack of tumor necrosis near vessels that results from inadequate freezing may contribute to local recurrence and thus limit the applications of this therapy. This study was designed to determine whether single-freeze cryoablation could cause necrosis of both the pervascular and intralesional hepatic parenchyma. METHODS: Ten pigs were treated with one 15-minute cycle of cryoablation. Five additional animals were treated with overlapping cryolesions to simulate a double freeze. After 24 hours, animals underwent reoperation with portal vein cannulation and infusion of formalin. Serial sectioning and hematoxylin and eosin staining of cryolesions were performed. RESULTS: Complete cell death was visualized within all cryolesions. There was no difference between once or twice-frozen tissue. Vessels within or adjacent to cryolesions showed necrosis of hepatic tissue up to the vessel wall. No sections revealed incomplete necrosis of perivascular hepatic parenchyma. CONCLUSIONS: Single-freeze cryoablation results in necrosis of intralesional hepatic parenchyma without added benefit from repeat freezing. Complete necrosis of the perivascular tissue suggests that cryosurgical ablation can effectively cause necrosis immediately adjacent to vessels without concerns of incomplete ablation resulting from the heat sink effect.

Animals↗
PubMed1997

CT depiction of experimental liver tumors: contrast enhancement with hepatocyte-selective iodinated triglyceride versus conventional techniques.

PURPOSE: To compare findings at computed tomography (CT) enhanced with a hepatocyte-selective contrast agent (iodinated triglyceride) and/or iohexol and at CT during arterial portography (CTAP). MATERIALS AND METHODS: Rabbit livers were directly inoculated with VX2 carcinoma. Results were compared for five helical CT examinations: unenhanced CT, iohexol-enhanced CT (600 mg iodine per kilogram of body weight [mg I/kg]), CTAP (with iohexol [600 mg I/kg]), triglyceride-enhanced CT (126 mg I/kg), and dual-contrast-enhanced CT (triglyceride plus iohexol [425 mg I/kg]). Attenuation of normal liver and tumor were compared with analysis of variance techniques and blinded reader evaluations. RESULTS: Normal liver attenuation was greatest at CTAP (127.3 HU +/- 5.3 [mean +/- standard error of the mean]), followed by dual-contrast-enhanced CT (112.4 HU +/- 1.2), iohexol-enhanced CT (97.9 HU +/- 2.2), triglyceride-enhanced CT (82.3 HU +/- 1.1), and unenhanced CT (54.9 HU +/- 1.8). Liver-to-lesion attenuation difference at triglyceride-enhanced CT was significantly greater than at iohexol-enhanced CT (P < .05), and attenuation differences at dual-contrast-enhanced CT were comparable to those at CTAP. Tumors did not enhance at triglyceride-enhanced CT, which increased conspicuity. Sensitivity values for lesion detection at dual-contrast-enhanced CT were greater than those at iohexol-enhanced CT or at CTAP (P < .05). CONCLUSION: At CT enhanced with triglyceride (especially when combined with iohexol), sensitivity values and liver-to-lesion attenuation differences were greater with lower iodine doses than with iohexol or at CTAP.

Animals↗
PubMed1996

Purification and characterization of a novel restricted antigen expressed by normal and transformed human colonic epithelium.

A cell surface antigen that is expressed by normal and 95% of transformed colonic epithelium and is recognized by the monoclonal antibody A33 (Welt, S., Divgi, C. R., Real, F. X., Yeh, S. D., Garin-Chesa, P., Finstad, C. L., Sakamoto, J., Cohen, A., Sigurdson, E. R., Kemeny, N., Carswell, E. A., Oettgen, H. F., and Old, L. J. (1990) J. Clin. Oncol. 8, 1894-1906) has been purified to homogeneity from the human colonic carcinoma cell line LIM1215. The A33 protein was purified from Triton X-114 extracts of LIM1215 cells under nondenaturing conditions. These extracts were applied sequentially to Green-Sepharose HE-4BD, Mono-Q HR 10/10, Superose 12 HR 10/30, and micropreparative Brownlee Aquapore RP 300. The purification was monitored by biosensor analysis using surface plasmon resonance detection with a F(ab')2 fragment of the humanized A33 monoclonal antibody immobilized on the sensor surface and Western blot analysis following SDS-polyacrylamide gel electrophoresis (PAGE) under nonreducing conditions using humanized A33 monoclonal antibody. The purified A33 antigen has a Mr on SDS-PAGE of 43,000 under nonreducing conditions. By contrast, the purified protein displayed a Mr of approximately 180,000 under native conditions on both size exclusion chromatography and native PAGE, possibly due to the formation of a homotetramer. N-terminal amino acid sequence analysis of the purified protein identified 34 amino acid residues of a unique sequence: ISVETPQDVLRASQGKSVTLPXTYHTSXXXREGLIQWD. A polyclonal antibody was raised against a synthetic peptide corresponding to residues 2-20 of this sequence. The antipeptide serum recognized the purified protein using Western blot analysis under both nonreducing (Mr 43,000) and reducing (Mr 49,000) conditions.

Amino Acid Sequence↗
PubMed1996

A randomized comparison of iodixanol and iohexol in adult body computed tomography scanning.

RATIONALE AND OBJECTIVES: We compared the safety and imaging efficacy of iodixanol-270 (270 mg I/ml), iodixanol-320 (320 mg I/ml), both of which are isosmolal to blood, and iohexol-300 (300 mg I/ml) for body computed tomography (CT) scanning. METHODS: One hundred twenty-six patients from the University of Wisconsin Hospital and Temple University Hospital scheduled to undergo body CT examinations were randomly assigned to receive either iodixanol-270, iodixanol-320, or iohexol-300. Patients were monitored with questioning and vital signs before injection, immediately after injection, and at 24 and 48 hr. Extensive laboratory evaluation also was performed. RESULTS: No serious reactions or deaths occurred in any group. The occurrence of overall minor adverse events (usually warmth, headache, taste distortion, rash) was similar for the different groups. Laboratory results showed no significant difference across groups. There was no significant difference in image quality detected among groups. CONCLUSION: There was no detectable difference in safety and imaging efficacy among the three contrast groups in this study. However, patients from the University of Wisconsin experienced significantly less injection discomfort with iodixanol-270 than with iohexol-300. Large clinical studies may more definitively determine the presence and nature of the relative advantages of iodixanol compared with currently available ionic and nonionic contrast agents.

Contrast Media↗
PubMed1996

Computed tomography scanning of Morris hepatomas with liver-specific polyiodinated triglycerides.

RATIONALE AND OBJECTIVES: We compared the computed tomography (CT) scanning characteristics of a polyiodinated triglyceride analog with those of a urographic agent to distinguish Morris-7777 hepatoma (MH) cells from normal hepatocytes in rats. METHODS: Eighteen Buffalo rats were laparotomized and MH cells injected directly into the hepatic parenchyma or introduced via the portal vein to produce, respectively, focal or diffuse lesions in the liver. Baseline CT scans were obtained 21 days after implantation and prior to intravenous administration of either the polyiodinated triglyceride (45-100 mg I/kg) or the nonionic contrast agent, iohexol (560 mg I/kg). Images were obtained at 0-3 hr and 24 hr. Gross pathologic inspection was performed to validate the imaging results. RESULTS: Hepatomas were nearly isodense with normal liver parenchyma in many of the animals, rendering lesion detection difficult with no contrast agent. The bolus administration of iohexol improved lesion detection in many cases. Lesion conspicuity, however, was significantly improved with the polyiodinated triglyceride at less than one eighth the dose of iohexol. CONCLUSION: Because of their biochemical nature, polyiodinated triglyceride analogs are specifically cleared by the liver. Consequently, they offer several advantages over nonspecific urographic agents in their ability to enhance lesion conspicuity in this hepatoma model.

Animals↗
PubMed1996

Magnetic resonance imaging detection of extraluminal enterally administered gadopentetate dimeglumine in a rat model of intestinal ischemia.

RATIONALE AND OBJECTIVES: We assessed whether intestinal ischemia would result in transudation of orally administered gadopentetate dimeglumine into the peritoneal cavity. METHODS: Twenty-eight rats were anesthetized and midline laparotomy was performed. Animals were divided into four groups: control, ligation of a single mesenteric arcade, ligation of six consecutive arcades, and ligation of the anterior mesenteric artery (analogous to the superior mesenteric artery in humans). A 1.0-ml enteric bolus of gadopentetate dimeglumine diluted with sterile water (1:1) was given via gavage. Magnetic resonance imaging was performed 2 hr after laparotomy and reviewed for the presence of intraperitoneal gadopentetate dimeglumine by two experienced observers. Animals were sacrificed 24 hr after surgery for pathologic examination. RESULTS: Four animals died prior to sacrifice. The bladder had a grossly high signal in all cases, implying some degree of intravascular absorption of the contrast material. A correlation was found between increasing mean radiology scores and increasing numbers of ligated vessels. The intraperitoneal signal tended to be higher in experimental animals than in control animals. Histologic damage was more severe in experimental animals (ischemic changes extending deeper into the intestinal wall) than in control animals. CONCLUSION: Direct visualization of spilled gastrointestinal gadopentetate dimeglumine helped discriminate ischemic from control rats in this model.

Administration, Oral↗
PubMed1996

Detection of malignant tumors using Tc-99m labeled Fab' fragments from a monoclonal antibody with specificity for D-dimer of cross-linked fibrin.

The authors present the case studies of two patients whose malignant tumors were detected with a Tc-99m labeled antifibrin monoclonal antibody (DD-3B6/22), which is specific for cross-linked fibrin. The first case was a malignant fibrous histiocytoma involving the proximal aspect of the left thigh, whereas in the second case, the patient was receiving treatment for a squamous cell carcinoma of the right mainstem bronchus. The results highlight the potential of this anti-D-dimer radiopharmaceutical for noninvasive detection of malignant tumors.

Aged↗
PubMed1996

Conventional color Doppler velocity sonography versus color Doppler energy sonography for the diagnosis of acute experimental torsion of the spermatic cord.

OBJECTIVE: We compared color Doppler velocity sonography and color Doppler energy sonography for the diagnosis of spermatic cord torsion in a canine model and determined the degree of torsion necessary to acutely halt testicular blood flow. MATERIALS AND METHODS: Spermatic cord torsion was created in five dogs by exposing and rotating the ipsilateral testis 0 degree, 180 degrees, 270 degrees, 360 degrees, 450 degrees, and 540 degrees. Detorsion followed. The testicles were scanned at each torsion stop using both color Doppler velocity sonography and color Doppler energy sonography. Doppler parameters were optimized (by phantom and test scans) and maintained at a tolerable noise level throughout the experiment. Readers who were unaware of the degree of torsion compared flow in the rotated and contralateral control testes. RESULTS: Flow became undetectable by color Doppler velocity sonography and color Doppler energy sonography at 450 degrees in four of five cases and at 540 degrees in one of five cases. We found no significant difference between the velocity and the energy techniques for detecting this absence of flow (p > .05, Wilcoxon test). We found a significant difference in degree of flow for both techniques when comparing controls and all degrees of torsion combined (p < .006, Mann-Whitney test), but significance was achieved at lesser degrees of torsion with the velocity technique than with the energy technique (180 degrees and 360 degrees, respectively, Wilcoxon test). CONCLUSION: Color Doppler energy sonography was not significantly more sensitive than color Doppler velocity sonography for the diagnosis of spermatic cord torsion in this model. Complete occlusion of arterial inflow occurred at 450-540 degrees of torsion.

Animals↗