PubMed Health⌕ Search

Biomedical subjects

J F Debatin

Publications and source records attributed to J F Debatin.

At least 181 records · Page 10Linked to original sources
PubMed1994

Renal artery blood flow: quantitation with phase-contrast MR imaging with and without breath holding.

PURPOSE: To compare the accuracy of 16-frame cine phase-contrast (PC) magnetic resonance (MR) imaging with those of two breath-hold PC techniques in the measurement of renal artery blood flow. MATERIALS AND METHODS: In vitro flow measurements were performed in a segment of harvested human artery embedded in gel. For the cine PC acquisition, respiratory motion was simulated. In eight subjects with recently obtained para-amino-hippurate-clearance renal blood flow data, renal artery flow measurements were subsequently performed with two breath-hold imaging techniques and with cine PC imaging during shallow respiration. RESULTS: Breath-hold sequences were significantly more accurate than conventional cine PC sequences both in vitro (P < .005) and in vivo (P < .05). Cine PC imaging tended to overestimate flow (in vivo mean, 24.47% +/- 9.94), reflecting artifactual enlargement of the apparent vessel size. CONCLUSION: Reliable blood flow measurements in the renal artery are possible with breath-hold PC MR imaging.

Adult↗
PubMed1994

Normal heart: evaluation with echo-planar MR imaging.

PURPOSE: To evaluate the appearance of the heart on spin-echo (SE) and gradient-echo (GRE) echo-planar magnetic resonance (MR) images. MATERIALS AND METHODS: Nine healthy volunteers were examined with an MR imager with transaxial echo-planar imaging (EPI) capabilities. SE EPI and GRE EPI sequences were used. Full k-space signal was obtained with readout time of 40 msec per image, and total image acquisition time was 72 and 52 msec, respectively, for SE EPI and GRE EPI. RESULTS: Delineation of cardiac structures was superior with SE EPI, reflective of significantly higher contrast between myocardial and intraluminal signal intensity (SI) (P < .001). The higher (P < .01) and more homogeneous (P < .001) intraluminal SI with GRE EPI allowed better assessment of intracardiac flow. Septal SI was significantly higher for GRE EPI (P < .01), but signal homogeneity was similar for both sequences (P > .2). CONCLUSION: Diagnostic images of the heart were obtained with both SE EPI and GRE EPI. GRE EPI is more suitable for flow studies because of the higher and more homogeneous intravascular SI.

Adult↗
PubMed1994

Color Doppler sonography of focal gastrointestinal lesions: initial clinical experience.

Graded compression color Doppler sonography was used to evaluate gastrointestinal blood flow in 20 normal fasting subjects and 32 patients with focal gastrointestinal lesions. Imaging was optimized for color sensitivity using a 5 MHz linear array transducer. Criteria were established for normal mural blood flow based on findings in normal controls. Two reviewers blinded to the final diagnosis compared patterns of mural vascularity in normal and abnormal patients. Increased mural blood flow was demonstrated in all 32 patients with gastrointestinal inflammatory disorders and in seven of nine patients with neoplasms. No mural flow was demonstrated in four patients with small bowel infarction. The greatest overall degree of flow was noted in patients with Crohn's disease and cytomegalovirus colitis. Flow in tumors was variable, ranging from strikingly increased flow in a giant villoglandular polyp to absent flow in a metastasis from lung carcinoma. Our preliminary experience suggests that the presence of considerable overlap in the color Doppler patterns of mural blood flow in inflammatory and neoplastic lesions. Color Doppler sonography alone without spectral waveform analysis may not distinguish focal inflammatory from neoplastic disorders of the gastrointestinal tract reliably. However, this technique potentially may be useful in diagnosing small bowel ischemia when thickened segments of small bowel are identified with absent flow.

Adult↗
PubMed1994

Cardiac volumetry. Comparison of echoplanar and conventional cine-magnetic resonance data-acquisition strategies.

RATIONALE AND OBJECTIVES: Ejection fraction (EF) measurements obtained using conventional cine-magnetic resonance imaging (MRI) are accurate but time-consuming. With echoplanar imaging (EPI), these data can be acquired much faster. In this study, EF and cardiac output (CO) measurements based on EPI data are compared with those measurements based on cine-MRI images. METHODS: Twelve subjects were examined on a 1.5-T imager equipped with a special EPI gradient system. The entire heart was imaged with contiguous axial 10-mm sections using cine-MRI and EPI techniques. With cine-MRI, 20 frames were acquired over 256 cardiac cycles; with EPI, 24 frames were obtained over four RR intervals using an electrocardiogram-triggered four-shot acquisition strategy. Ejection fraction and CO were calculated based on the summation of the individual end-systolic and end-diastolic volumes. Ejection fraction and CO measurements based on the two different data sets were compared. RESULTS: Multishot EPI was 50 times faster than cine-MRI. The short acquisition time permitted breath-hold imaging. The high temporal (16 to 24 frames/RR interval) and spatial resolution (1.56 x 1.56 mm in plane) of the multishot EPI images enabled delineation of the ventricular lumen at end-systole and end-diastole in a fashion similar to cine-MRI. Echoplanar imaging EF and CO measurements correlated well with cine-MRI EF measurements, with correlation coefficients of 0.96 and 0.94, respectively. The 95% confidence interval of the EF measurement differences between the two techniques was narrow, ranging from -5.2 to 5.7 EF percentage points. CONCLUSIONS: Accurate volumetric EF and CO measurements are possible based on ultrafast multishot EPI data sets as part of an integrated MRI-based cardiac evaluation.

Adult↗
PubMed1994

[MR angiography of pelvic and abdominal vessels].

The assessment of abdominal vessels with conventional methods is invasive and frequently does not yield an accurate diagnosis, particularly in the evaluation of the portal venous system. MR angiography is non-invasive and is well suited for the examination of abdominal vessels. Both vessel morphology and intravascular flow patterns can be characterized with this method. Clinical indications include portal hypertension, portal vein thrombosis, portosystemic shunts, assessment of congenital anomalies, thrombus, and tumor propagation into the inferior vena cava and the renal veins, proximal renal artery stenosis, and assessment of the pelvic arteries and veins. In the future, MR angiography may become an important part of the non-invasive evaluation of abdominal and pelvic vessels.

Abdomen↗
PubMed1993

Renal magnetic resonance angiography in the preoperative detection of supernumerary renal arteries in potential kidney donors.

RATIONALE AND OBJECTIVES: Careful evaluation of the renovascular anatomy in potential living-related kidney donors is essential regarding the presence of accessory renal arteries. Conventional arteriography remains the standard of evidence for delineating the renal arterial supply. We assessed the utility of two-dimensional phase contrast (PC) magnetic resonance angiography (MRA) in the workup of potential living-related renal donors. METHODS: Thirty-nine patients were examined with conventional arteriography and MRA, which was performed on a 1.5-T system using a two-dimensional PC technique in both coronal and axial planes (repetition time[TR]/echo time [TE] = 39/8.5 msec; flip 60 degrees; matrix 256 x 128; field of view, 28 cm2; 2 excitations; first-order gradient-moment nulling; 7-mm section with 2-mm overlap). The number of hilar and polar supernumerary renal arteries was determined. Hilar supernumerary arteries were classified as co-dominant if they were similar in size to the ipsilateral main renal artery. RESULTS: Conventional arteriography identified 78 dominant and 13 supernumerary (3 co-dominant, 10 accessory) renal arteries. Magnetic resonance angiography identified the proximal 35 mm of all 78 dominant and the 3 co-dominant renal arteries. Of the remaining ten (7 polar and 3 hilar) accessory vessels, only four were correctly identified with MRA. CONCLUSION: The high error rate (60%) suggests that two-dimensional PC MRA, as implemented, should not be used in the preoperative evaluation of potential renal donors.

Adult↗
PubMed1993

Pulmonary angiography with MR imaging: preliminary clinical experience.

PURPOSE: To study the accuracy of magnetic resonance (MR) pulmonary angiography in 20 patients in whom pulmonary embolism (PE) was clinically suspected. MATERIALS AND METHODS: Fourteen patients (group 1) were recruited for the MR pulmonary angiography study before they underwent conventional pulmonary angiography (CPA) based on clinical findings. Six patients (group 2) did not undergo CPA but were considered to have PE on the basis of findings in other studies. MR venography was performed at the time of MR pulmonary angiography in 13 patients. RESULTS: MR pulmonary angiography had a sensitivity of 92%-100% and specificity of 62% for detection of PE. Performance of MR pulmonary arteriography and MR venography in a single examination to demonstrate thrombus in both the arterial and deep venous systems was proved feasible. CONCLUSION: This report describes an early clinical implementation of new MR pulmonary angiographic techniques. Further advances to improve specificity by enhancing sensitivity to slow flow and increasing spatial resolution are necessary before routine clinical use of MR pulmonary angiography is justified.

Adult↗
PubMed1993

Pilocytic astrocytoma: correlation between the initial imaging features and clinical aggressiveness.

OBJECTIVE: Astrocytomas are classified as either fibrillary or pilocytic on the basis of their histologic appearance. The imaging features of the fibrillary astrocytoma correlate closely with the tumor's clinical aggressiveness and are, therefore, useful in predicting prognosis. Correlation between the imaging features and the clinical aggressiveness of the pilocytic astrocytoma, however, is not well established. Accordingly, we compared the initial MR and CT appearances of the lesion with tumor aggressiveness as seen clinically to determine if a correlation exists. MATERIALS AND METHODS: We retrospectively evaluated the initial MR images or CT scans of 32 consecutive patients who had a histologic diagnosis of pilocytic astrocytoma. The lesions were evaluated with regard to location, size, calcification, morphology, and degree of contrast enhancement. These initial imaging features were correlated with the aggressiveness of the tumor as seen clinically. Tumors were classified as aggressive or nonaggressive on the basis of their clinical manifestations. Patients with clinically aggressive lesions had progressive symptoms and radiologic evidence of tumor progression or recurrence within an unusually short period. Patients with clinically nonaggressive lesions had a more indolent course, either improving or remaining stable, on both clinical and radiologic evaluations. In 12 patients, the tumor was classified as aggressive clinically, either progressing or recurring within a median time of 7.5 months (range, 2.5-118 months) from the initial diagnosis. The remaining 20 patients had a clinically nonaggressive course. RESULTS: In our series of patients, lesion size and location were not significantly different between the nonaggressive and aggressive tumors, as noted clinically. Furthermore, the aggressive and nonaggressive tumors were similar with regard to the presence or absence of calcium. Most tumors in both groups showed either moderate or marked enhancement and were multilobular. CONCLUSION: The initial CT and MR features of pilocytic astrocytoma are unreliable for predicting which lesions will behave in a more aggressive manner clinically and have a poor prognosis.

Adolescent↗
PubMed1992

Phase III clinical evaluation of gadoteridol injection: experience in pediatric neuro-oncologic MR imaging.

Twenty-two pediatric patients with known CNS neoplasms underwent magnetic resonance (MR) imaging before and after intravenous injection of 0.1 mmol/kg gadoteridol injection as part of a Phase IIIB open label multicenter clinical trial. Intravenous administration of this neutral, nonionic contrast agent was found to be safe in children. No clinically relevant changes in vital signs or laboratory values (including complete blood count, blood chemistry, serum electrolytes, thyroid and metabolic panel and clotting function) were attributed to the administration of gadoteridol injection. There were no systemic complaints. The imaging characteristics of gadoteridol in pediatric CNS disease appeared similar to those of gadopentetate dimeglumine. Contrast enhancement was present in 17 of 22 patients (77%). The administration of gadoteridol injection provided additional clinically relevant information including improved visualization and delineation of the primary lesion, detection of additional lesions, determination of tumor recurrence and narrowing the list of differential considerations in all 17 enhancing studies as well as in 2 of 5 studies without signal intensity enhancement. The very low toxicity, inherent to this nonionic low osmolal paramagnetic contrast formulation may allow administration of increased doses at increased infusion rates for an increased number of indications with improved sensitivity.

Adolescent↗
PubMed1992

Renal revascularization: indications and results.

Although the prevalence of renovascular hypertension is low, clinical criteria can select a population in which renovascular hypertension is significantly more common (prevalence of 15%). In these selected patients, it is appropriate to proceed to a screening modality to look for a significant renal artery stenosis. Choices of the noninvasive methods include captopril-enhanced renal scintigraphy, magnetic resonance (MR) angiography, and intravenous digital subtraction renal angiography (DSRA). Intraarterial DSRA or conventional arteriography may also be used to reliably detect renal artery stenosis, with the advantage that both the diagnostic and the interventional procedure can be performed at the same setting. A high percentage of a group of patients who are selected by means of clinical and arteriographic studies will benefit from revascularization. Thus, the renal artery angioplasty may be performed during the arteriogram in which the stenosis is confirmed.

Adult↗
PubMed1992

Detection of acute avascular necrosis of the femoral head in dogs: dynamic contrast-enhanced MR imaging vs spin-echo and STIR sequences.

OBJECTIVE: Spin-echo MR imaging has been shown to be highly sensitive in the detection of avascular necrosis. Very early avascular necrosis can, however, appear normal on MR images. We compared dynamic contrast-enhanced MR imaging with conventional spin-echo and short Tl inversion-recovery (STIR) sequences for detecting acute osteonecrosis in an animal model. MATERIALS AND METHODS: Avascular necrosis was induced unilaterally in the femoral heads of five dogs that were imaged with a 1.5-T system within 3 hr of devascularization. After standard T1-weighted, T2-weighted, and STIR images, gradient-recalled echo images, 28/5 (TR/TE) with a 45 degrees flip angle, were obtained at 6-sec intervals for 90 sec synchronous with the IV administration of 0.2 mmol of gadoteridol per kilogram of body weight at a rate of 2 ml/sec via an automated injector. Two animals were reimaged after 7 days. RESULTS: Spin-echo and STIR images did not show any acute changes in the ischemic femoral heads. In contrast, significant differences were present in the enhancement profiles of the marrow spaces in the normal and ischemic femoral heads (p = .005). Normal marrow was characterized by rapid enhancement, with an average signal intensity increase of 83% peaking at 36 sec; no measurable enhancement was seen in the marrow of the ischemic femoral head. Spin-echo images, obtained 7 days after devascularization (n = 2), showed changes characteristic of avascular necrosis. Dynamic contrast-enhanced MR images showed persistent lack of enhancement in the avascular marrow of the ischemic femoral head. A junctional zone, characterized by rapid contrast enhancement in excess of 120% without early washout, was identified at the interface between normal and avascular marrow. CONCLUSION: In this experimental model, dynamic contrast-enhanced MR imaging proved significantly more sensitive than conventional spin-echo and STIR imaging in the detection of acute avascular necrosis.

Acute Disease↗
PubMed1992

Magnetic resonance imaging--cardiac ejection fraction measurements. Phantom study comparing four different methods.

The accuracy of cardiac ejection fraction (EF) measurements with thin, contiguous cine-magnetic resonance imaging (MR) sections is well established. Still, faster imaging and measurement techniques would be desirable. The authors evaluated the accuracy of four different MR EF measurements methods in a biventricular, anthropomorphic, foam-latex rubber phantom which was connected via noncompliant fluid-filled tubing to a pulsatile flow pump. Nine contiguous 10 mm cine-MR sections (TR/TE, 25/13; flip angle, 45 degrees) were obtained through the heart in long and short cardiac axes at 16 frames per cardiac cycle at a pump rate of 60 beats/minute. EF measurements were based on either the multi-slice summation technique (nine contiguous 10-mm sections versus four 10-mm sections spaced 10 mm apart) or the area-length method (single largest long section versus combination of largest long- and short-axis section). Three replications were performed for each of the tested EFs (40.8%, 29.4%, and 13.4%), which were compared with actual EFs. EF measurements based on contiguous 1-cm sections correlated best with the actual EFs. Average relative errors ranged from 3.2% to 6.0%. EF measurements based on every other section were less accurate; average relative errors were between 5.2% and 10.2%. Single and biplane area-length algorithm EF measurements were significantly less accurate; average relative errors were as high as 59%. EF measurements based on multi-slice summation are more accurate than those based on the area-length algorithm. Contiguous 1-cm section acquisitions are most accurate and most time consuming. With slight decrease of accuracy, acquisition and processing times can be halved by skipping every other slice.

Humans↗
PubMed1991

Selective use of low-osmolar contrast media.

Two thousand thirty-four consecutive patients presented for excretory urography within a 22-month period. Of 57 observed adverse reactions (incidence 2.8%), 54 occurred in 1219 low-risk patients injected with conventional ionic contrast media (HOCM) (incidence 4.4%) while three reactions were noted in the 815 high-risk patients receiving low-osmolar contrast media (LOCM) (incidence 0.4%). Despite strict enforcement of an unchanging list of high-risk criteria by the same pool of radiologists, LOCM use was not constant, increasing in use over time from 26.5% to 55.3% of urograms. In addition, frequency of LOCM selection increased transiently (from 33% to 52%) following a single life-threatening reaction to HOCM. Our results suggest that strict guidelines for use of LOCM are subject to loose individual physician interpretation. Physicians' perceptions of safety made it increasingly difficult to withhold LOCM and progressively more patients were included in high-risk groups.

Adolescent↗
PubMed1991

Imaging of the renal arteries: value of MR angiography.

We compared the efficacy of MR angiography with that of conventional angiography for visualizing the renal arteries and detecting renovascular disease. Thirty-three MR angiographic studies, consisting of axial two-dimensional (2-D) phase-contrast, coronal 2-D phase-contrast, and coronal 2-D time-of-flight acquisitions, were performed within 48 hr of conventional arteriography. The studies were done to evaluate possible renovascular hypertension (n = 25) or potential donor nephrectomy (n = 8). The three MR image sets were interpreted independently, in random order by three observers, with regard to the number of renal arteries, degree of vessel visualization, arteriovenous overlap, and presence of renovascular disease. A fourth interpretation was based on the combined axial and coronal phase-contrast image sets. Evaluation was limited to the proximal 35 mm of each renal artery. Renal artery visualization and detection of renovascular disease were more complete with coronal phase-contrast (80% sensitivity, 91% specificity) than with time-of-flight (53% sensitivity, 97% specificity) images. Combined axial and coronal phase-contrast images permitted visualization of the proximal 35 mm of all dominant renal arteries and detection of 13 of 15 stenoses (87% sensitivity, 97% specificity). Our data suggest that biplanar MR angiography has considerable potential as a noninvasive screening technique for the evaluation of renovascular disease.

Angiography↗
PubMed1990

Indium 111 white blood cell imaging of epididymitis.

The clinical diagnosis of epididymitis is frequently substantiated radiographically with pertechnetate 99m (99mTc) testicular scintigraphy and scrotal sonography. Indium 111 (111In) autologous leukocyte imaging in a patient with epididymitis has to our knowledge not been reported previously. The case presented is an elderly man with epididymitis. An 111In-labelled white blood cell scan demonstrated increased tracer accumulation in the region of the right epididymis. This suggests that 111In-labelled leukocyte scanning may be helpful in evaluating an inflammatory process involving the epididymis or testis and potentially may allow for differentiation of epididymitis and orchitis from missed torsion, tumour or cystic lesions.

Bone and Bones↗
PubMedDate not supplied

Cardiac ejection fraction: phantom study comparing cine MR imaging, radionuclide blood pool imaging, and ventriculography.

The accuracy and reproducibility of cardiac ejection fraction (EF) measurements based on cine magnetic resonance (MR) imaging, radionuclide multigated acquisition (MUGA) blood pool imaging, and angiographic ventriculography were evaluated by comparing them with a volumetrically determined standard. A biventricular, compliant, fluid-filled heart phantom was developed to mimic normal cardiac anatomy and physiology. Ventricular EFs were measured with cine MR imaging by summation of nine contiguous 10-mm-thick sections in short and long axis, with single-plane ventriculography, and with MUGA. Three measurements were performed with each modality for each of three EFs. Ventriculography was least accurate, with average relative errors ranging from 7.9% for the largest EF to 60.1% for the smallest. Cine MR was most accurate, with average relative errors ranging from 4.4% to 8.5%. MUGA EF measurements showed good correlation, with average relative errors ranging from 7.1% to 22.4%. Comparison of the error variances for the three modalities with the F test revealed that MR and MUGA EF measurements were significantly more accurate than those based on ventriculography (P less than .01). No significant difference was demonstrated between the accuracy of short- and long-axis cine MR acquisitions.

Gated Blood-Pool Imaging↗