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J F Debatin

Publications and source records attributed to J F Debatin.

At least 145 records · Page 8Linked to original sources
PubMed1997

Intravascular MR imaging of atherosclerotic plaque: ex vivo analysis of human femoral arteries with histologic correlation.

PURPOSE: To assess the potential role of intravascular magnetic resonance (MR) imaging with receiver coils mounted to an inflatable balloon in characterizing atherosclerotic plaque. MATERIALS AND METHODS: Twelve human harvested segmental femoral arteries with atherosclerotic changes were studied with a 5-F imaging balloon catheter equipped with a single-loop wire receiver coil. Imaging was performed with an open-configuration 0.5-T (n = 6) or a 1.5-T (n = 6) MR system, with T1- and T2-weighted sequences. Histologic analysis was the reference standard, and MR images were analyzed with regard to vessel wall thickness, plaque area, and components. RESULTS: Images acquired at 1.5 T were characterized by better in-plane resolution (117 x 104 microm). Resolution at 0.5 T (234 x 178 microm) was sufficient to discriminate the wall layers. On T2-weighted images, adventitia, media, and thickened intima could be discriminated. T1-weighted images did not permit differentiation between wall layers. There was good correlation between MR and histologic measurements of wall thickness (r = .97) and plaque area (r = .98). Plaque characterization was possible on T2-weighted images. Calcified plaque was identified as areas of low signal intensity (134 +/- 98) and could be differentiated from fibrous structures containing collagen (1,968 +/- 680) or fatty components (762 +/- 394). CONCLUSION: Intravascular MR imaging on the basis of the balloon catheter design enables differentiation of wall layers and plaque components.

Aged↗
PubMed1997

Dynamic contrast-enhanced FMPSPGR of the pancreas: impact on diagnostic performance.

OBJECTIVE: The objective of this study was to evaluate the diagnostic impact of dynamic contrast-enhanced fast multiplanar spoiled gradient-recalled imaging (FMPSPGR) of the pancreas. MATERIALS AND METHODS: MR imaging examinations of the upper abdomen for 101 patients were evaluated retrospectively and compared with histologic and surgical results as well as imaging or laboratory and clinical follow-up results. Standard T1-weighted spin-echo images, T2-weighted fast spin-echo images with fat saturation, and FMPSPGR had been obtained for all patients. Of the 101 patients, 79 also underwent fat-saturated contrast-enhanced T1-weighted spin-echo MR imaging. Qualitative analysis consisted of evaluation of overall image quality and characterization of the pancreas as normal or abnormal, for which receiver operating characteristic curves were calculated. A contrast-to-noise ratio between the pancreas and the surrounding tissue was calculated for each patient. RESULTS: By a statistically significant margin, FMPSPGR performed better than conventional spin-echo MR imaging. For FMPSPGR, sensitivity and specificity were 87% and 100%, respectively, compared with T1-weighted spin-echo sequences (sensitivity, 50%; specificity, 96%), T2-weighted spin-echo sequences with fat saturation (sensitivity, 60%; specificity, 93%), and contrast-enhanced T1-weighted spin-echo sequences with fat saturation (sensitivity, 53%; specificity, 90%). Diagnostic confidence was highest with FMPSPGR. CONCLUSION: FMPSPGR should be used in all MR imaging examinations of the upper abdomen. This technique offers better visualization of important structures and increases confidence for a more specific and accurate diagnosis than does conventional spin-echo imaging.

Contrast Media↗
PubMed1997

MR angiography of patients with peripheral arterial disease before and after transluminal angioplasty.

OBJECTIVE: This study was performed to evaluate the feasibility of using MR angiography for following up patients who have undergone interventional therapy of the infrapopliteal vascular bed. SUBJECTS AND METHODS: Fourteen patients with peripheral vascular disease underwent MR imaging before and after percutaneous transluminal angioplasty (PTA) using a two-dimensional time-of-flight technique (TR/TE, 33/3.9; section thickness, 2.9 mm). As the gold standard, selective digital subtraction angiography was obtained for all evaluated extremities before and after PTA. For data analysis, the distal peripheral arterial system was divided into 11 segments: the popliteal artery; the tibioperoneal trunk; and the proximal, mid, and distal portions of the three trifurcation vessels. Each segment was characterized as normal, mildly diseased, moderately diseased, severely diseased, or occluded. RESULTS: We found overall agreement between the two techniques in 110 segments (71%) and 123 segments (80%) on data obtained before and after PTA, respectively. Before PTA, our interpretation of MR angiograms overestimated 14 lesions (9%). After PTA, we overestimated five lesions (3%) on MR angiograms. We underestimated lesion severity in 30 cases (19%). The high incidence of agreement between the two techniques was reflected by the high Kendall's tau-beta values of .83 and .87 for data obtained before and after PTA, respectively. CONCLUSION: The excellent depiction of the PTA-induced morphologic changes suggests great potential for the use of MR angiograms during interventional follow-up.

Aged↗
PubMed1997

Active biplanar MR tracking for biopsies in humans.

OBJECTIVE: The purpose of this study was to assess the potential of active biplanar MR needle tracking in a 0.5-T open-configuration MR system. A needle design characterized by an integrated internal signal source was used. To evaluate the performance of this new technique in vivo as well as in vitro, procedures were performed on patients. CONCLUSION: The results of this study prove that the biplanar tracking concept can be applied in a clinical environment. The applicability of biplanar tracking is further enhanced by integrating an internal signal source.

Adult↗
PubMed1997

Real-time monitoring of laser diskectomies with a superconducting, open-configuration MR system.

OBJECTIVE: The objective of our study was to assess the ability of a 0.5-T superconducting, open-configuration MR system to guide laser diskectomies. The study was performed ex vivo on six human cadavers as well as in vivo on three patients. CONCLUSION: The macroscopic size of necrosis correlated well with the monitored temperature spread (r2 = .76-.85). After MR-guided introduction of the laser fiber into the targeted disk space, temperature spread was visualized in all subjects.

Adolescent↗
PubMed1996

Azygos blood flow: phase contrast quantitation in volunteers and patients with portal hypertension pre- and postintrahepatic shunt placement.

Flow volume in the azygos venous system was quantitated with Cine-phase contrast (PC) velocity mapping in volunteers and compared with patients with known portal hypertension, who were referred for transjugular intrahepatic portosystemic shunt (TIPS) placement. Subsequently, the TIPS-induced hemodynamic effects on portal and azygos flow were analyzed. To assess intra- and intersubject variability, flow in the azygos veins was measured in each of 10 normal subjects at three different times. Subsequently, portal and azygos flow was quantitated in 20 patients with portal hypertension, before and after TIPS placement. All imaging was performed on a 1.5-tesla magnetic resonance imaging (MRI) system. Azygos flow was measured transaxially at the midthoracic level. Cine-PC flow measurements of the main portal vein followed morphological evaluation of the portal venous system with axial and coronal breath-held magnet resonance angiogram. Azygos flow in normal subjects was characterized by high inter- and low intrasubject variability. Azygos flow in patients with portal hypertension was significantly higher (P < .001). Following successful TIPS placement in 18 patients, Cine-PC revealed a mean decrease in azygos flow of 46.3% (P < .001) and a 134% (P < .001) increase of portal flow. Reflecting the complexity of portal hemodynamics, there was no correlation between the changes in the portal and azygos systems. In 2 patients with early occlusion of TIPS, documented invasively, portal and azygos flow values remained largely unchanged. Cine-PC enables the noninvasive, quantitative assessment of flow within the azygos venous system. Azygos flow was found to be markedly elevated in patients with portal hypertension. Combined portal and azygos PC flow measurements quantitate the therapeutic effect of TIPS placement.

Adult↗
PubMed1996

Biopsy needle susceptibility artifacts.

Understanding the appearance of thin metallic structures in magnetic resonance imaging is important for evaluating the potential role of MRI in guiding and monitoring percutaneous interventions. As most MR compatible instruments are made from materials with a susceptibility different from water, their visibility is enhanced beyond what is expected on the grounds of displaced water alone. Unfortunately, this artifactually enhanced visibility is not constant, but instead depends on a variety of factors. This article presents computer simulations of the image distortion resulting from magnetic susceptibility differences between a needle and the surrounding tissue. The simulations show not only an artifact size that is dependent on needle composition, orientation, and pulse sequence, but also a corresponding shift of the artifact center away from the actual center of the needle. These effects place limits on the accuracy of MRI-guided needle tip placement.

Artifacts↗
PubMed1996

Ultra-high-speed MR imaging.

Conventional magnetic resonance imaging (MRI) has been shown to provide excellent morphological images of the body organs, particularly structures undergoing little physiologic motion. Nevertheless, the clinical usefulness of MRI has been hampered by long acquisition times, high cost of scanning because of limited patient throughput, and image artifacts due to patient motion. With recent technical developments, several ultrafast scanning techniques capable of acquiring images in a breath-hold now find their introduction into clinical use. The system improvements are potentially useful for a vast range of applications hitherto not accessible to MR imaging. Among these are functional brain imaging, realtime imaging of cardiac motion and perfusion, fast abdominal imaging, improved MR angiography, and potentially real-time monitoring of interventional procedures. Whereas some ultrafast techniques can be performed on conventional scanners, echo-planar imaging, the fastest currently available data acquisition strategy, requires specially designed hardware. This article provides an overview of the technical advances in ultrafast MRI and discusses potential applications and the possible future impact on body scanning.

Humans↗
PubMed1996

Technical note--approach to myocardial perfusion with echo planar imaging.

PURPOSE: To evaluate the feasibility of MRI-based myocardial first-pass contrast perfusion imaging with a multi-shot echo planar imaging (EPI) technique. SUBJECTS AND METHODS: A non-sequential (ECG-triggered) gradient echo two-shot EPI acquisition strategy capable of covering the entire heart in contiguous 10-mm sections every two cardiac cycles with an in-plane resolution of 1.56 X 1.56 mm was implemented on a 1.5-T Signa Advantage Scanner equipped with prototype hardware for non-resonant EPI in the transverse plane. The heart of a single volunteer was studied prior to and following the intravenous bolus application of a paramagnetic contrast agent (Gd-DOTA, 0.2 mmol/kg). RESULTS: Twelve contiguous transaxial 10-mm EPI images were obtained every two RR intervals for a total of 40 s. The myocardial contrast perfusion study was technically adequate. Contrast caused a signal loss of 87% in the right and 67% in the left ventricle and 59% in the myocardium. CONCLUSION: First-pass myocardial perfusion imaging with a gradient echo, two-shot echo planar imaging strategy is feasible.

Adult↗
PubMed1996

Towards active guidewire visualization in interventional magnetic resonance imaging.

Improving the visibility of interventional devices is of paramount importance if MRI-guided fluoroscopy is to become a reality. Passive visualization is problematic in that the susceptibility-induced artifacts are material- and orientation-dependent. Here a concept is presented for making interventional devices visible. It involves fitting a device with a straight-wire antenna. As the sensitivity of such an antenna is highest for signal sources in the immediate neighborhood, using the antenna for reception gives an outline image. In this manner a guidewire or other interventional device could be made MRI-visible. The image appearance of a straight-wire antenna depends on the orientation of the device with respect to the main magnetic field and imaging plane. This phenomena is discussed theoretically and documented with MR images.

Catheterization↗
PubMed1996

[Puncture with an open-sided, interventional MRI system. Illustration with a case report].

INTRODUCTION AND METHODS: A 0.5 T open-configuration MR system allows free access to the patient via a 58-cm-wide opening on both sides of the machine. A newly developed system for needle guidance enables the examiner to perform biopsies in combination with real-time imaging and to position laser fibers in the human body. For imaging, a 2D gradient echo sequence is used (TR 19 ms, TE 9 ms, flip angle 30 degrees FOV 24 x 24 cm, slice thickness 10 mm matrix 256 x 128). The acquired images are displayed on two LCD screens localized within the MR system, thus allowing an interactive needle guidance. This procedure is illustrated by a case report. DISCUSSION: The handling of the system for needle guidance was simple, mainly due to a real-time adaption of the scan plane to the needle direction. The possibility of multi-angulated approaches makes biopsies of hardly accessible anatomic regions feasible. CONCLUSION: We think that MR-guided needle positioning will play an important role in combination with thermosensitive therapies. Thermosensitivity of MR imaging allows extensive monitoring of such interventions.

Adult↗
PubMed1996

[Influence of respiration and pulsatility on the accuracy of MR-phase contrast flow measurements: "in vitro" evaluation].

PURPOSE: Determination of the influence of pulsatility of blood flow and respiration-induced vascular motion on the accuracy of MR phase contrast flow measurements. MATERIAL AND METHODS: Flow measurements in phantoms were performed with the phase contrast technique in a 1.5 Tesla MRI system using different flow volumes, varying degrees of flow pulsatility and a varying number of image phases. To determine the influence of respiratory motion on flow measurement accuracy, flow data was collected during motion of the whole phantom. RESULTS: Flow measurements based on 6 and 16 image phases were significantly more accurate (p < 0.05) than those based on one phase. An increase in the degree of pulsatility resulted in a widening of the error range. Hence, increasing pulsatility demands an increase in the number of acquired phases to maintain sufficient measurement accuracy. Simulated respiratory motion with an excursion depth of only 5 mm resulted in a significant overestimation of true flow ranging between 22.9 and 42.1%. Measurements without simulated respiratory motion were more accurate (p < 0.001). An excursion depth of 15 mm led to a vast increase in the apparent vessel size in excess of 100%. Flow volume measurements increased accordingly to 1126 ml/min (true flow = 720 ml/min). CONCLUSION: Accurate phase-contrast based flow measurements require an adjustment of acquisition parameters to correspond to the physiology of the vessel under consideration. Flow data in vessels subject to respiratory motion should only be collected in apnoea.

Blood Flow Velocity↗
PubMed1996

[Virtual intravascular endoscopy in the renal arteries: a new way of observing 3-D-MIR angiography data sets].

PURPOSE: To determine the potentials and limitations of a recently developed algorithm for virtual intravascular endoscopy (VIE) based on 3-dimensional (3-D) magnetic resonance (MR) data sets. METHOD: The data from 6 patients derived from gadolinium-enhanced MR angiography of the renal arteries were reviewed. All patients had unilateral or bilateral renal arterial pathologies (stenoses n = 2, aneurysms n = 4). Imaging was performed on a 1.5-T scanner using a 3-D gradient-echo MR sequence. The imaging parameters were as follows: TR/TE/flip angle 3.9/1.9/40 degrees, matrix 256 x 192, slice thickness 1.5 to 2 mm, FOV 32 cm, and 48 slices. Image acquisition time was 28 seconds under apnoeia conditions. A total of 60 ml 0.5 molar Gd-DTPA was injected during the scan. RESULTS: 3-D data sets could be obtained in all patients and postprocessed for VIE. The intraluminal vessel wall was depicted with high clarity in all cases. All pathologies that were not intraparenchymal could be easily seen. Limitations to the technique include the image quality of the original data set, use of the ideal threshold to minimise intraluminal artifacts, and a complicated prescription sequence. CONCLUSIONS: We have shown that VIE can be consistently performed in the renal arteries using MR data sets acquired with a contrast enhanced 3-D gradient-echo technique. It provides a hitherto unused approach to viewing 3-D vascular MR data sets.

Adolescent↗
PubMed1996

[Interactive stereotaxic interventions in superconducting, open 0.5-Tesla MRI tomography].

PURPOSE: Evaluation of an interactive, stereotactic biopsy device integrated in an open superconductive 0.5 tesla MR-scanner with a vertical gap. MATERIAL AND METHODS: In addition to "in-vitro" experiments performed on a plexiglas phantom with holes of varying diameters (5-20 mm) biopsies on eleven patients (7 women, 4 men; average age 55 years) were performed in the interventional MR-system. Lesions in the abdomen (n = 6), muscle (n = 1), thyroid (n = 3) and breast (n = 1) were targeted with 18-20 G aspiration biopsy needles of 5-15 cm length. The intervention was interactively guided by a fast T1-weighted 2-D gradient echo sequence. RESULTS: All of the 15 and 20 mm holes of the phantom, but only 83% of the 10 and 5 mm holes were hit. No complications occurred during the MR-guided patient procedures. All lesions (mean size 3.5 cm, distance from the skin 2 cm to 10 cm) were biopsied successfully. The fast image acquisition in combination with the stereotactic technique enables interactive control of the needle. CONCLUSIONS: Stereotactic, interactively controlled biopsies in the interventional MR are technical feasible. However, the range of meaningful indications for MR-guided biopsies is limited.

Abdominal Neoplasms↗
PubMed1996

Bleeding anorectal varices: successful treatment with transjugular intrahepatic portosystemic shunting (TIPS).

A patient with severe recurrent rectal bleeding from anorectal varices due to portal hypertension because of hepatitis C virus related liver cirrhosis is presented. As illustrated by the report, it is essential to differentiate bleeding anorectal varices from bleeding haemorrhoids because treatment is different. In our patient, implantation of a transjugular intrahepatic portosystemic shunt (TIPS) led to an impressive regression of the anorectal varices, which could be demonstrated by sigmoidoscopy, endosonography, and magnetic resonance imaging. Recurrent rectal bleeding in a patient with portal hypertension should alert the physician to consider anorectal varices. Endoscopic ultra-sound and magnetic resonance imaging are new and non-invasive modalities for diagnosis and post-treatment control.

Aged↗
PubMed1996

Human aorta: preliminary results with virtual endoscopy based on three-dimensional MR imaging data sets.

PURPOSE: To determine the feasibility of use of magnetic resonance (MR) imaging data sets to perform virtual intraarterial endoscopy (VIE). MATERIALS AND METHODS: Seven female and 14 male patients (aged 9-86 years [mean, 42 years]) with various pathologic aortic conditions underwent three-dimensional gadolinium-enhanced spoiled gradient-echo MR imaging. With prototype software, VIE postprocessing algorithms (based on ray casting) were applied to the imaging data sets. Findings at conventional angiography were used as the standards of reference. RESULTS: The vessel wall was seen from the inside in each case, and the following pathologic conditions were depicted clearly: the two lumina in a congenial double aortic arch and the single lumen after correction, vessel narrowing in coarctations, characteristics of Leriche syndrome, stenoses, occlusions, and the true and false lumina of dissections. CONCLUSIONS: Limitations of VIE include the image quality of the original data set, the threshold chosen to minimize intraluminal artifacts, and the inherent smoothing of vessel walls.

Adult↗
PubMed1996

Breath-hold, contrast-enhanced, three-dimensional MR angiography.

Breath-hold gadolinium-enhanced three-dimensional magnetic resonance (MR) angiography was performed with a high-performance gradient MR imaging system in 10 volunteers with no history of vascular abnormalities (breath-hold interval, 28 seconds; repetition time, 4.0 msec; echo time, 1.9 msec; 0.4 mmol gadoterate meglumin per kilogram of body weight). High-resolution three-dimensional time-of-flight angiograms of the aorta, renal arteries, pulmonary arteries, pelvic arteries, and portal venous system were successfully acquired in all cases.

Adolescent↗