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Biomedical subjects

E K Yucel

Publications and source records attributed to E K Yucel.

At least 55 records · Page 3Linked to original sources
PubMed1995

Magnetic resonance angiography in the evaluation of living-related renal donors.

Live-donor kidney donation requires an accurate determination of renal arterial anatomy. Traditionally, conventional angiography has supplied this information. The present study was undertaken to determine the accuracy of magnetic resonance angiography (MRA) compared with conventional angiography (CA) in the evaluation of potential living renal donors. Fifteen potential living renal donors underwent both conventional angiography (midstream aortic injection) and three-dimensional phase contrast MRA. Two overlapping volumes of 64 slices (slice thickness 1.5 mm) were obtained in the axial plane to allow coverage from the celiac trunk to the aortic bifurcation. Conventional angiography demonstrated single renal arteries in 24 kidneys and multiple renal arteries in 6 kidneys. Magnetic resonance angiography demonstrated multiple renal arteries in 5 of the 6 kidneys. The sensitivity of MRA in determining kidneys with multiple renal arteries was 83% (5/6). One kidney with an accessory 2-mm polar artery was incorrectly identified as having a single renal artery by MRA. The overall accuracy of MRA in identifying the number of renal arteries was 97% (29/30). Fibromuscular dysplasia was demonstrated in 2 patients by CA, but was not visualized prospectively by MRA. Based on standard physician and hospital fees for each procedure, use of MRA alone would represent a cost savings of approximately $1900 over CA. Despite its minimally invasive and economic attractions, MRA does not achieve the level of accuracy required to replace CA in the evaluation of potential living kidney donors.

Female↗
PubMed1995

Pancreatic duct: MR cholangiopancreatography with a three-dimensional fast spin-echo technique.

PURPOSE: To determine the role of three-dimensional fast spin-echo magnetic resonance (MR) cholangiopancreatography in the evaluation of the normal and abnormal pancreatic duct. MATERIALS AND METHODS: A non-breath-hold MR cholangiopancreatographic technique with use of a body coil was compared with direct pancreatography performed with endoscopic retrograde cholangiopancreatography in 37 patients. RESULTS: MR cholangiopancreatograms of satisfactory quality were obtained in 92% of patients. Sensitivity for detection of pancreatic duct dilatation (n = 15) was 100% and 87% (observers 1 and 2, respectively). Among patients with pancreatic duct strictures (n = 8), 75% of the strictures were detected; there was a single false-positive finding. Specificity for both observers was 69% for the maximum intensity projection reconstructions and increased to 81% with review of the source images. Four of six cases of pancreas divisum (67%) and two cases of pancreatic duct stones were demonstrated. Interobserver agreement was moderate to substantial, as assessed with kappa-analysis. CONCLUSION: MR cholangiopancreatography can accurately demonstrate the normal pancreatic duct as well as various pancreatic duct abnormalities.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1995

MR cholangiopancreatography: efficacy of three-dimensional turbo spin-echo technique.

OBJECTIVE: The purpose of this study was to correlate a new three-dimensional turbo spin-echo MR cholangiopancreatography technique with endoscopic cholangiopancreatography or percutaneous cholangiography to determine the efficacy of the new technique for visualizing and diagnosing diseases of the pancreatic and biliary ducts. It was hypothesized that the new technique would provide diagnostic images without prolonged breath holding or a surface coil as required by previous MR techniques. SUBJECTS AND METHODS: We describe a respiratory-triggered, heavily T2-weighted, three-dimensional, multislab turbo spin-echo sequence for MR cholangiopancreatography. Thirty patients with suspected biliary or pancreatic disease were randomly selected from referrals for endoscopic retrograde cholangiopancreatography. All patients were imaged with the optimized MR technique prior to attempted endoscopic or percutaneous cholangiopancreatography. The MR images were evaluated without additional clinical or radiographic information by consensus opinion of two of the authors for visualization and caliber of the ducts. When the ducts were abnormal, the level and probable cause were categorized as follows: normal, periampullary stricture, localized duct stenosis, multifocal strictures, calculous disease, duct anomalies, and cystic disease. The images obtained by conventional percutaneous or endoscopic cholangiopancreatography were evaluated in the same manner with the exception that additional clinical and radiologic information was provided. The diagnostic categories determined by MR and direct cholangiopancreatography were compared. Patients were included in the analysis only if endoscopic or percutaneous opacification of the biliary or pancreatic ducts was successful. RESULTS: Diagnostic MR images were obtained in 29 (97%) of 30 patients. Endoscopic or percutaneous cholangiopancreatography was successful in 21 of the 29 patients for the common bile duct and in 17 of the 29 patients for the pancreatic duct. The diagnosis for the common bile duct by the MR technique agreed with the diagnosis by endoscopic or percutaneous cholangiopancreatography in 19 (90%) of 21 patients. For diagnosis of diseases of the pancreatic duct, there was agreement in 15 (88%) of 17 patients. CONCLUSION: Respiratory-triggered, multislab, three-dimensional turbo spin-echo MR cholangiopancreatography is a noninvasive technique for visualization of the pancreatic and biliary ductal systems. It is capable of providing diagnostic information equivalent to invasive techniques in a large percentage of patients and should be the technique of choice when invasive techniques are incomplete, unsuccessful, or technically difficult.

Adolescent↗
PubMed1994

MR angiography of normal pelvic arteries: comparison of signal intensity and contrast-to-noise ratio for three different inflow techniques.

OBJECTIVE: Two-dimensional (2D) time-of-flight (TOF) MR angiography has been the standard technique for evaluating arteries of the lower extremity. However, this technique is limited by artifacts resulting from vessel pulsation, as well as by relatively poor vessel-to-background contrast. The purpose of this study was to evaluate two cardiac-gated inflow techniques to determine whether they exhibited better contrast and signal performance than the standard technique of 2D TOF MR angiography of the iliac arteries. SUBJECTS AND METHODS: Fourteen subjects who had no clinical evidence of vascular disease had standard 2D TOF, gated 2D TOF, and gated 2D turbo field-echo MR angiography. Images were evaluated for signal-intensity ratio, signal-to-noise ratio, and contrast-to-noise ratio, in addition to qualitative evaluation. RESULTS: Turbo field-echo MR angiography exhibited significantly higher signal-intensity, signal-to-noise, and contrast-to-noise ratios than did either gated or standard MR angiography for all vessel segments. We found no significant difference between gated and standard 2D TOF techniques for any vessel segment. Qualitative features of turbo field-echo MR angiography included improved visualization of horizontal vessel segments compared with the standard 2D TOF technique, less effective venous saturation compared with either the gated or standard 2D TOF technique, and increased ghosting artifacts compared with the gated 2D TOF technique. CONCLUSION: Two-dimensional turbo field-echo MR angiography exhibits improved signal and contrast for evaluation of normal iliac segments compared with standard or gated 2D TOF MR angiography. This technique should replace standard 2D TOF MR angiography for evaluation of the iliac arteries.

Adult↗
PubMed1993

Time of flight renal MR angiography: utility in patients with renal insufficiency.

We studied the renal arteries prospectively in 16 patients with renal insufficiency using a combination of two-dimensional and three-dimensional time of flight magnetic resonance angiography (MRA). Results were compared with conventional angiography. All renal arteries were identified by MRA. Accuracy for classifying renal arteries into patent, moderately (30-70%) stenotic, severely (> 70%) stenotic, or occluded was 91%. With regard to the presence or absence of severe occlusive disease (> 70% stenosis or occlusion) the sensitivity was 100%, with a specificity of 93%.

Aged↗
PubMed1993

The potential for lower extremity revascularization without contrast arteriography: experience with magnetic resonance angiography.

PURPOSE: We report an initial experience with 24 patients studied between March 1990 and April 1992 with magnetic resonance angiography (MRA) for lower extremity occlusive disease. METHODS: All patients underwent vascular intervention with either balloon angioplasty or bypass grafting, and in six patients this intervention was based on MRA findings alone. Eighteen patients were studied with both MRA and contrast arteriography, and there was observed agreement between the two studies in 98% of all arterial segments examined. RESULTS: Agreement between MRA and contrast arteriography was uniform for arterial segments below the inguinal ligament. Intraoperative findings and favorable early results of seven bypass grafts performed in six patients after MRA alone suggested this was a valid approach for patients at prohibitive risk of complications from contrast arteriography. CONCLUSIONS: Magnetic resonance angiography is accurate in demonstrating relevant anatomy in peripheral arterial occlusive disease and in selected patients may eliminate the need for contrast arteriography before lower extremity revascularization.

Angiography↗
PubMed1993

Atherosclerotic occlusive disease of the lower extremity: prospective evaluation with two-dimensional time-of-flight MR angiography.

A prospective, blinded comparison of two-dimensional time-of-flight (TOF) magnetic resonance (MR) angiography and conventional arteriography was performed in 25 patients who underwent routine arteriography for symptomatic atherosclerotic occlusive disease of the lower extremity. MR angiography was performed from the distal abdominal aorta through the popliteal trifurcation. The native arterial tree was divided into nine segments; each segment was assessed for patency (defined as stenosis < 50% of arterial diameter), moderate stenosis (50%-69%), severe stenosis (70%-99%), or occlusion (100%). In all 206 segments examined, the sensitivity of MR angiography in diagnosis of occlusion was 100%; the specificity, 98%. All long occlusions were correctly classified. In specific categories of occlusive disease, the sensitivity and specificity were as follows: in all segments with 70% or greater stenosis, including occlusions, 90% and 97%; in all segments with 50% or greater stenosis, including occlusions, 92% and 88%; in femoropopliteal segments with 50% or greater stenosis, 92% and 93%; and in iliac segments, 93% and 83%. Long occlusions were distinguished from short occlusions and stenoses; hence, MR angiography enabled identification of patients with lesions suitable for angioplasty.

Adult↗
PubMed1993

MR angiography of the portal and hepatic venous systems: preliminary experience with echoplanar imaging.

OBJECTIVE: The purpose of this study was to evaluate the ability of echoplanar MR angiography to depict the major hepatic and portal venous structures. SUBJECTS AND METHODS: Echoplanar and conventional MR angiographic examinations were performed in 10 subjects (seven healthy volunteers, three patients with focal hepatic lesions). A gradient-recalled echo (GRE) time-of-flight technique (125/10 [TR/TE], 90 degrees flip angle) was used for echoplanar angiography. Eight complete single-excitation images were acquired at each level in 1.5 sec and then collapsed into a single maximal intensity projection. Conventional time-of-flight MR angiography (34/13, 30 degrees flip angle) also was performed. The vascular anatomy from the right atrium to the splenic vein was imaged (6-mm contiguous levels) in three 10.5-sec breath-holds with echoplanar imaging, as compared with seven 11.5-sec breath-holds with conventional MR angiography. Echoplanar and conventional images were compared quantitatively and qualitatively. RESULTS: Echoplanar imaging was 61% faster than conventional MR angiography. Vessel-to-liver signal-intensity ratios were significantly higher for echoplanar imaging (p < .0001), signal-to-noise ratios were significantly higher for conventional MR angiography (p < .0001), and contrast-to-noise ratios were comparable. Qualitatively, echoplanar imaging and conventional MR angiography provided similar anatomic information about the hepatic and portal veins. CONCLUSION: Angiograms of the hepatic and portal venous systems that are of diagnostic quality can be acquired much more quickly with echoplanar imaging than with conventional MR angiography.

Echo-Planar Imaging↗
PubMed1993

Magnetic resonance angiography of the peripheral arteries.

MR angiography techniques have recently been applied to evaluation of peripheral vascular disease, both phase-contrast and time-of-flight techniques have been used. Preliminary clinical experience has shown promise in identification of angioplasty candidates, preoperative evaluation in iliofemoral occlusive disease, and identification of tibial run-off vessels.

Arterial Occlusive Diseases↗
PubMed1992

Color Doppler flow imaging appearance of a popliteal venous aneurysm.

Popliteal venous aneurysms are rare lesions that usually become evident when thrombus from within the aneurysm embolizes to the lungs. The authors report an unusual case in which the patient presented without thromboembolic complications. The appearance of a popliteal venous aneurysm at color Doppler flow imaging is described.

Adult↗
PubMed1992

Access-site thrombosis after placement of inferior vena cava filters with 12-14-F delivery sheaths.

Inferior vena cava filters were placed in 60 patients. Ultrasound (US) of the venous access site was performed before and 3-5 days after filter placement to determine the prevalence of occlusive and nonocclusive access-site thrombosis (AST). Prevalence of symptoms attributable to AST was also evaluated at 1-month clinical follow-up in 58 of the 60 patients. All filters were placed with delivery sheaths with outer diameters of 12-14 F. US depicted development of occlusive AST in six of the 60 patients (10%). Nonocclusive AST developed in 15 (25%). Symptoms related to AST occurred in two of 58 patients (3%). There was a substantially increased prevalence of occlusive thrombus in patients in whom partially occluding thrombus or extrinsic compression in the inferior vena cava or ipsilateral iliofemoral veins was demonstrated on vena cavograms obtained before filter placement. The prevalence of both symptoms attributable to AST and US-detected occlusive thrombus in this series with smaller delivery systems is lower than that reported after percutaneous placement of stainless steel Greenfield filters via 29.5-F (outer diameter) sheaths.

Adolescent↗
PubMed1992

Extension of saphenous thrombophlebitis into the femoral vein: demonstration by color flow compression sonography.

Five cases are presented in which compression and color flow sonography were used to diagnose extension of superficial saphenous thrombophlebitis into the deep system at the saphenofemoral junction. In one case thrombus originated in the calf, demonstrating an unusual mode of propagation into the deep venous system above the knee. Color Doppler imaging is especially helpful in diagnosing this complication of superficial thrombophlebitis.

Aged↗