Biomedical subjects

F T Lee

Publications and source records attributed to F T Lee.

103 records · Page 6Linked to original sources

PubMedDate not supplied

MR hysterosalpingography in a rabbit model.

Our objective was to evaluate the efficacy of MR imaging as compared with conventional hysterosalpingography (HSG) for the detection of fallopian tube patency after uterine injection of contrast material. Rabbit uterine horns (n= 18) were catheterized transvaginally. Five fallopian tubes were ligated and 11 were left unaltered. T1-weighted gradient-echo MR images were obtained before, during, and after injection of 1.0-3.0 mL of a dilute gadolinium-containing contrast agent. Corresponding conventional studies were performed with an equivalent volume of iohexol. Images were evaluated by two blinded readers. Observers agreed in all cases on the presence (n = 11) or absence (n = 5) of peritoneal spill with conventional HSG. Interpretation of MR HSG concurred with conventional HSG in 14 of 16 cases for each observer (P > .05). Reasons for misdiagnosis included small amounts of spill (n = 2), artifact (n = 1), and subtle spill between bowel loops (n = 1). Sensitivity and specificity for MR HSG were 95.5% and 70%, respectively, for the diagnosis of tubal patency/occlusions. No statistical difference was found between MR HSG and conventional HSG for the diagnosis of fallopian tube patency/obstruction. Potential advantages of MR HSG include no ionizing radiation, potentially diminished local contrast toxicity, superior visualization of uterine fibroids and endometriosis, and visualization of ovaries. We conclude that this technique warrants further study, including the use of a primate model to better simulate human anatomy.

Animals↗

PubMedDate not supplied

Reevaluation of plain radiographic findings in the diagnosis of aortic rupture: the role of inspiration and positioning on mediastinal width.

Despite the advent of newer imaging modalities, conventional radiography and clinical examination remain the primary screening method in evaluation of the mediastinum following blunt thoracic trauma. Mediastinal width (MW) is generally considered an important finding in assessing for aortic rupture. The degree of inspiration and patient positioning clearly affects MW, but is largely ignored in the literature. This study investigates the mediastinal widths of normal volunteers with differing degrees of inspiration and positioning, and compares them to radiographs of patients with known aortic ruptures. Mediastinal widths were obtained from chest radiographs of 16 patients with known aortic rupture, and from 50 volunteers using AP-inspiratory-supine, AP-expiratory-supine, and PA-inspiratory-upright technique. Upper 95% confidence limits were obtained for normals. A statistically significant difference in MW of normals was found between inspiratory-supine, expiratory-supine, and upright-inspiratory techniques. Compared to the same degree of inspiration in normals, 12 of 16 patients with aortic rupture had a MW above the upper 95% confidence limits. It is concluded that mediastinal width in normals is significantly affected by the degree of inspiration and positioning. When comparing mediastinal widths for normals and ruptures, there was a significant difference in MW for most degrees of inspiration. As depth of inspiration increased, differences between MW in controls and rupture patients increased. We conclude that patient positioning and degree of inspiration are important factors in assessing the mediastinum, and every effort should thus be made to obtain an upright-inspiratory film if clinically feasible prior to declaring a mediastinum as abnormal.

Adolescent↗

PubMedDate not supplied

Construction and characterisation of a functional CD19 specific single chain Fv fragment for immunotherapy of B lineage leukaemia and lymphoma.

The B cell specific antigen CD19 is a target for the immunotherapy of B lineage leukaemias and lymphomas. We have engineered a single chain Fv (scFv) fragment from the mouse hybridoma cell line FMC63 which produces monoclonal antibody specific for CD19. The genes encoding the FMC63 heavy and light chain variable regions were amplified from cDNA and a scFv was constructed by splice overlap extension PCR. Analysis of staining of lymphoblastoid cell lines, peripheral blood lymphocytes and tonsil sections demonstrated that the monovalent scFv fragment has the same cellular specificity as the parent hybridoma antibody. Kinetic studies with radiolabelled material showed that the scFv binds target cells with a Ka of 2.3 x 10(-9), compared with 4.2 x 10(-9) for the parent antibody. This CD19 scFv will be used in experimental models to test its therapeutic efficacy and immunogenicity, with a view to application in the diagnosis and treatment of human B cell cancers.

Animals↗

PubMedDate not supplied

Elastographic imaging of thermal lesions in the liver in vivo following radiofrequency ablation: preliminary results.

Radiofrequency (RF) ablation is an interstitial focal ablative therapy that can be used in a percutaneous fashion. This modality provides in situ destruction of hepatic tumors. However, local recurrence rates after RF ablative therapy are as high as 34% to 55%, believed to be due in part to the inability to visualize accurately the zone of necrosis (thermal lesion). This can lead to the incomplete ablation of the tumor, generally in areas near the tumor edges. In this paper, we show that ultrasound (US)-based in vivo elastography can accurately depict thermal lesions after thermal therapy. However, elastography of the liver and other abdominal organs is challenging due to the difficulty in providing controlled and reproducible compression. The use of the RF ablation probe as the compressor/displacement device reduces lateral slippage or nonaxial motion that may occur with externally applied compressions or imaging during the respiratory cycle. This technique also provides controlled and reproducible compressions of the liver for in vivo elastographic imaging. Comparison of elastograms with histology of ablated tissue demonstrates a close relationship between elastographic image features and histopathology.

Animals↗

PubMedDate not supplied

Preclinical evaluation of an iodinated particulate contrast agent for use during angiography: work in progress.

PURPOSE: To study the feasibility of using an iodinated particulate contrast agent, iodipamide ethyl ester (IDE), for angiography. MATERIALS AND METHODS: IDE at doses of 40-100 mg of iodine per kilogram was diluted to a total volume of 5-20 mL and used for digital subtraction angiography in nine dogs under general anesthesia. Equivalent images were obtained by using water-soluble contrast medium (WSCM) for comparison (iohexol) in seven animals. All images were reviewed by blinded reviewers and graded subjectively on a five-point scale. RESULTS: Angiographic studies of multiple vascular territories performed with IDE yielded images of slightly lower overall quality compared with images obtained with WSCM (P = .14, Mann-Whitney U test). Arterial phase images were subjectively superior with WSCM when compared with IDE (P < .0001, chi 2.) Depiction of the corresponding veins during the venous phase on the IDE angiograms was superior to that on WSCM angiograms in 12 of 21 cases, although this did not reach statistical significance (P > .05 chi 2). Images of the renal vein and portal vein achieved with IDE were graded as superior to those achieved with WSCM in eight of 10 reviews. CONCLUSION: Angiography is feasible with IDE. Compared with WSCM, IDE produced images of lesser quality during the arterial phase, but of equal or superior quality in the venous phase depending on the vessel studied. Because it is excreted slowly in bile and is isotonic, it may prove useful in patients with renal insufficiency, diabetes, multiple myeloma, or severe coronary disease.

Angiography, Digital Subtraction↗

PubMedDate not supplied

Rationale for the combination of cryoablation with surgical resection of hepatic tumors.

Only 5% to 10% of metastatic and primary liver tumors are amenable to surgical resection. Hepatic cryoablation has increased the number of patients who are suitable for curative treatment. The aim of this study was to evaluate survival and intrahepatic recurrence in patients treated with cryoablation and resection. From June 1994 to July 1999, thirty-eight surgically unresectable patients underwent a total of 42 cryoablative procedures for 65 malignant hepatic lesions. Twenty patients underwent cryoablation alone, and 18 patients were treated with a combination of resection and cryoablation, with a minimum of 18 months' follow-up. The 38 patients had the following malignancies: primary hepatocellular carcinoma (n = 8) and metastases from colorectal cancer (n = 21), neuroendocrine tumors (n = 3), ovarian cancer (n = 3), leiomyosarcoma (n = 1), testicular cancer (n = 1), and endometrial cancer (n = 1). Patients were evaluated preoperatively with spiral CT scans and intraoperatively with ultrasound examinations for lesion location and cryoprobe guidance. Local recurrence was detected by CT. Major complications included bleeding in three patients and acute renal failure, transient liver insufficiency, and postoperative pneumonia in one patient each. Two patients (5%) died during the early postoperative interval; mean hospital stay was 7.1 days. Median follow-up was 28 months (range 18 to 51 months). Overall survival according to Kaplan-Meier analysis was 82%, 65%, and 54% at 12, 24, and 48 months, respectively. Forty-eight-month survival was not significantly different between those patients undergoing cryoablation alone (64%) and those treated with a combination of resection and cryoablation (42%). Disease-free survival at 45 months was 36% for patients undergoing cryoablation plus resection compared to 25% for those undergoing cryoablation alone. Local recurrences were detected at five cryosurgical sites, for a rate of 12% overall (5 of 42), 11% (2 of 18) for patients in the cryoablation plus resection group, and 12% (3 of 24) for those in the cryoablation alone group. For patients with colorectal metastases, survival was 70% at 30 months compared to 33% for hepatocellular cancer and 66% for other types of tumors. Patients with tumors larger than 5 cm or numbering more than three did not have significantly decreased survival. Cryoablation of hepatic tumors is a safe and effective treatment for some patients not amenable to resection. The combination of cryoablation and resection results in survival comparable to that achieved with cryoablation alone.

Adult↗

PubMedDate not supplied

Pneumoperitoneum in peritoneal dialysis patients: significance of diagnosis by CT.

OBJECTIVE: Pneumoperitoneum diagnosed by plain radiography is often a sign of gastrointestinal perforation and is unusual (0.17%) in patients on continuous ambulatory peritoneal dialysis (CAPD). These patients are prone to bacterial peritonitis, which can have overlapping clinical findings with perforated viscus. Because CT is often used to screen symptomatic CAPD patients, the reliability of pneumoperitoneum as a diagnostic sign is examined. MATERIALS AND METHODS: Records of 433 CAPD patients were examined; of these, 56 patients had had CT while on CAPD (rupture, 6; nonrupture, 50). Plain radiography and CT were examined for free air and fluid. Patients were classified according to the amount of free air detected. RESULTS: Patients with ruptured viscus had pneumoperitoneum in 5 of 6 cases by CT and 4 of 6 by plain radiography. Excluding free air, ruptured viscus could only be diagnosed in 1 of the 6 patients by CT. Patients without rupture had pneumoperitoneum in 15 of 50 cases by CT and 2 of 46 by plain radiography. No instance of pneumoperitoneum was discovered on plain radiography and not CT. CONCLUSION: Pneumoperitoneum was found by CT in 30% of nonrupture CAPD patients, therefore, CT appeared to be more sensitive than plain radiography for its detection. The presence, quantity, and distribution of free air are not helpful in separating perforations from nonperforations. The lack of pneumoperitoneum on CT was found to be a useful but not absolute diagnostic sign to exclude gastrointestinal rupture.

Aged↗

PubMedDate not supplied

Imaging efficacy of a hepatocyte-selective polyiodinated triglyceride for contrast-enhanced computed tomography.

RATIONALE AND OBJECTIVES: DHOG-LE is an injectable polyiodinated triglyceride lipid emulsion providing contrast enhancement of the liver in CT. Studies were conducted to characterize the imaging efficacy of various DHOG-LE formulations as a function of both the administered iodine dose and the formulation composition. MATERIALS AND METHODS: Four DHOG-LE preparations consisting of either 10, 20, 25, or 30% (w/v) total lipid were administered to anesthetized female Sprague Dawley rats as single intravenous bolus doses of 50, 100, 150, and/or 300 mg I/kg (n = 3 to 6 rats/formulation and dose). A 25% triolein lipid emulsion prepared without iodine was administered as a vehicle control at the highest dose volume (n = 6). Liver enhancement was evaluated as a function of time (0 to 24 hours) after administration of contrast by analyzing regions of interest from sequential body scans. RESULTS: At all dose levels, liver enhancement was observed after injection of each DHOG-LE formulation. Regardless of formulation composition, similar enhancement of the liver was noted when administered at an equivalent iodine dose. Liver enhancement increased proportionately with increasing iodine dose. Mean peak intensities for 50, 100, 150, and 300 mg I/kg doses were 78 HU (42% above baseline), 101 HU (84% above baseline), 125 HU (127% above baseline), and 195 HU (255% above baseline), respectively. Liver time-intensity profiles exhibited rapid uptake, prolonged enhancement up to 3 hours, and complete clearance of the majority of the formulations tested by 24 hours. Time and duration of peak intensities were also directly related to iodine dose. CONCLUSIONS: In the animal model tested, DHOG-LE imaging efficacy was directly related to iodine dose and was independent of formulation composition. Thus, administration of DHOG-LE in highly concentrated lipid preparations minimized administered dose volume and resulted in appreciable liver enhancement, even at the lowest dose of 50 mg I/kg.

Animals↗

PubMedDate not supplied

Quality assessment and clinical research: a collaborative approach.

Obtaining physician commitment to and continued involvement in quality assessment activities can be difficult. Some physicians view quality assessment as a bureaucratic morass that fails to improve patient care. However, by combining quality assessment and clinical research, insight into practice patterns can be obtained and physicians might be more likely to express interest in quality assessment issues. We reviewed medical records of patients at our hospital on peritoneal dialysis (PD) to determine the rate of free air found in normal PD patients. This was compared to PD patients with known gastrointestinal perforation; free intra-abdominal air has been described as a sign of gastrointestinal perforation. Documentation of free air and its significance in radiology reports were noted. Fifty-nine of 59 (100%) cases had available radiology reports. Documentation of free air was present in only 5 of 23 (22%) cases, and its significance was noted in the same 5 of 23 (22%). These results were communicated within the hospital, and a subsequent improvement in free-air detection, documentation, and reporting--both oral and written--was noted by the clinical service. The documentation of radiological findings is a frequently used monitor in radiology quality assessment. Our study identified a clinical and documentation problem, quantified the deficiency, and took steps toward improvement while simultaneously performing clinical research. We conclude that quality assessment and clinical research can coexist and serve to improve clinical practice while encouraging physician involvement in quality assessment programs.

Data Collection↗

PubMedDate not supplied

CT angiography of potential renal transplant donors.

Renal transplantation has grown rapidly over the past 30 years, resulting in an inadequate supply of organs to meet the ever-increasing demand. This has led to an increase in the number of living-related donors. Advances in imaging technology now allow safe, rapid, and relatively noninvasive evaluation of potential donors. Helical computed tomographic (CT) angiography is a fast, minimally invasive procedure that is quickly becoming the imaging modality of choice for preoperative evaluation of potential renal transplant donors. Helical CT, combined with low-osmolar intravenous contrast materials, has enabled CT angiography to depict arterial and venous anatomy accurately. Between July 1995 and March 1997, CT angiography was performed in 205 potential renal donors. Correlation with surgical findings in 136 donor nephrectomies helped confirm a high level of accuracy for CT angiography in the assessment of the renal vasculature: Sensitivity and specificity for identifying specific vessels was 99.6% and 99.6% for main renal arteries, 76.9% and 89.9% for polar arteries, and 98.7% and 95.5% for main renal veins, respectively. CT angiography allows the radiologist to provide the transplant surgeon with precise preoperative anatomy of the renal vasculature, thus reducing the risks and complications associated with the harvesting procedure and improving the chances for a successful outcome. However, accurate radiologic interpretation depends on the radiologist's experience level, attention to detail, and commitment to careful image evaluation.

Angiography↗

PubMedDate not supplied

Invasive procedures in the female pelvis: value of transabdominal, endovaginal, and endorectal US guidance.

Transabdominal, endovaginal, and endorectal ultrasonographic (US) guidance is indispensable for a multitude of invasive procedures in the female pelvis. Transabdominal uterine US performed with a fluid-filled bladder is appropriate and convenient for guidance of difficult dilation and curettage procedures. Transabdominal intraoperative US can be employed to guide several procedures for which the more expensive intraoperative hysteroscopic procedure is now used. Aspiration of symptomatic ovarian cysts that appear benign at US with an endovaginally guided small-gauge needle is simple and effective. Simple noninfected pelvic fluid collections may be aspirated transvaginally for both diagnosis and therapy by using endovaginal guidance. Endovaginal US demonstrates the anatomic relationships of a pelvic abscess to adjacent structures, allowing safe access for transvaginal drainage. By using an endovaginal transducer with a needle guide, cervical and vaginal cuff masses may be easily sampled. An obstructed uterus may be accessed by puncturing obstructive tissue with a trocar-containing needle guided by an endorectal probe. US guidance for placement of a central brachytherapy tandem is performed via the abdominal approach after the bladder has been distended with sterile water. Endorectal US transducers may be effectively used to guide placement of interstitial brachytherapy needles in pelvic soft-tissue masses.

Biopsy, Needle↗

PubMedDate not supplied

Three-dimensional CT angiography of spontaneous portosystemic shunts.

Spontaneous portosystemic shunts (varices) are a well-known complication of severe liver disease and portal hypertension. Computed tomographic (CT) angiography was used to image the hepatic vasculature of 198 patients with end-stage liver disease in anticipation of liver transplantation. Performance of a delayed acquisition during the portal phase of enhancement enables evaluation of portal and variceal anatomy without the need for an additional injection of contrast material. Three-dimensional (3D) reconstruction of portal-phase CT angiograms enhances the perception of the courses and anatomic relationships of varices. This information is valuable for surgical planning. Common varices include the left gastric vein, short gastric veins, paraumbilical veins, and splenic vein; in cases of more unusual, complex shunts, 3D rendering is indispensable. By precisely demonstrating the courses of varices, CT angiography allows the surgeon to plan the operative approach and determine the need for surgical varix ligation or preoperative interventional embolization.

Angiography↗

PubMedDate not supplied

Non-contrast-enhanced helical computed tomography for the evaluation of patients with acute flank pain.

The purpose of this study was to determine the sensitivity, specificity, and positive predictive value of non-contrast-enhanced helical CT as the primary imaging modality for the evaluation of patients with acute flank pain at the University of Wisconsin. A retrospective review of 163 computed tomography (CT) examinations, dating from 3/4/97 to 3/25/98, was performed. Statistical calculations were performed using only clinically-confirmed data. Sixty-five true positives, 3 false positives, 64 true negatives, and 1 false negative yield a sensitivity of 98.5%, a specificity of 95.5%, and a positive predictive value of 95.6%. A timely diagnosis of non-genitourinary system pathology occurred in 7% of cases, improving the overall efficacy of this modality for the evaluation of flank pain. The University of Wisconsin experience confirms the accuracy and efficacy of using non-contrast-enhanced helical CT in the diagnosis of a suspected obstructing ureteral calculus. The highly accurate and timely diagnosis of an obstructing ureteral calculus, or of extraurinary tract pathology, establishes non-contrast-enhanced helical CT as the diagnostic study of choice for the evaluation of the patient with acute flank pain.

Acute Disease↗