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Biomedical subjects

J F Debatin

Publications and source records attributed to J F Debatin.

208 records · Page 12Linked to original sources
PubMedDate not supplied

MR-guided cholecystostomy: assessment of biplanar, real-time needle tracking in three pigs.

PURPOSE: To demonstrate the feasibility of magnetic resonance (MR)-guided cholecystostomy using active, real-time, biplanar MR tracking in animal experiments. METHODS: Experiments were performed on three fully anesthetized pigs in an interventional MR system (GE open). The gallbladder was displayed in two orthogonal planes using a heavily T2-weighted fast spin-echo sequence. These "cholangio roadmaps" were displayed on LCD monitors positioned in front of the interventionalist. A special coaxial MR-tracking needle, equipped with a small receive-only coil at its tip, was inserted percutaneously into the gallbladder under continuous, biplanar MR guidance. The MR-tracking sequence allowed sampling of the coil (needle tip) position every 120 msec. The position of the coil was projected onto the two orthogonal "cholangio roadmap" images. RESULTS: Successful insertion of the needle was confirmed by aspiration of bile from the gallbladder. The process of aspiration and subsequent instillation of Gd-DTPA into the gallbladder was documented with fast gradient-recalled echo imaging. CONCLUSION: Biplanar, active, real-time MR tracking in combination with "cholangio roadmaps" allows for cholecystostomies in an interventional MRI environment.

Animals↗
PubMedDate not supplied

MR-guided percutaneous angioplasty: assessment of tracking safety, catheter handling and functionality.

PURPOSE: Magnetic resonance (MR)-guided percutaneous vascular interventions have evolved to a practical possibility with the advent of open-configuration MR systems and real-time tracking techniques. The purpose of this study was to assess an MR-tracking percutaneous transluminal angioplasty (PTA) catheter with regard to its safety profile and functionality. METHODS: Real-time, biplanar tracking of the PTA catheter was made possible by incorporating a small radiofrequency (RF) coil in the catheter tip and connecting it to a coaxial cable embedded in the catheter wall. To evaluate potentially hazardous thermal effects due to the incorporation of the coil, temperature measurements were performed within and around the coil under various scanning and tracking conditions at 1.5 Tesla (T). Catheter force transmission and balloon-burst pressure of the MR-tracking PTA catheter were compared with those of a standard PTA catheter. The dilatative capability of the angioplasty balloon was assessed in vitro as well as in vivo, in an isolated femoral artery segment in a swine. RESULTS: The degree of heating at the RF coil was directly proportional to the power of the RF pulses. Heating was negligible with MR tracking, conventional spin-echo and low-flip gradient-echo sequences. Sequences with higher duty cycles, such as fast spin echo, produced harmful heating effects. Force transmission of the MR-tracking PTA catheter was slightly inferior to that of the standard PTA catheter, while balloon-burst pressures were similar to those of conventional catheters. The MR-tracking PTA catheter functioned well both in vitro and in vivo. CONCLUSION: The in vivo use of an MR-tracking PTA catheter is safe under most scanning conditions.

Angioplasty, Balloon↗
PubMedDate not supplied

Pulmonary hemorrhage: imaging with a new magnetic resonance blood pool agent in conjunction with breathheld three-dimensional magnetic resonance angiography.

PURPOSE: To describe the three-dimensional magnetic resonance angiography (3D MRA) imaging appearance of the pulmonary arteries following administration of a superparamagnetic iron oxide blood pool agent to human volunteers, and to demonstrate in an animal model (pigs) how this technique can be used to detect pulmonary parenchymal hemorrhage. METHODS: Two volunteers were examined following the intravenous administration of a superparamagnetic iron oxide blood pool agent (NC100150 Injection, Nycomed Amersham Imaging, Wayne, PA, USA). T1-weighted 3D gradient recalled echo (GRE) image sets (TR/TE 5.1/1.4 msec, flip angle 30 degrees ) were acquired breath-held over 24 sec. To assess the detectability of pulmonary bleeding with intravascular MR contrast, pulmonary parenchymal injuries were created in two animals under general anesthesia, and fast T1-weighted 3D GRE image sets collected before and after the injury. RESULTS: Administration of the intravascular contrast in the two volunteers resulted in selective enhancement of the pulmonary vasculature permitting complete visualization and excellent delineation of central, segmental, and subsegmental arteries. Following iatrogenic injury in the two animals, pulmonary hemorrhage was readily detected on the 3D image sets. CONCLUSION: The data presented illustrate that ultrafast 3D GRE MR imaging in conjunction with an intravenously administered intravascular blood pool agent can be used to perform high-quality pulmonary MRA as well as to detect pulmonary hemorrhage.

Adult↗
PubMedDate not supplied

MRI of absent left pulmonary artery.

Unilateral absence of a pulmonary artery, more accurately referred to as unilateral proximal interruption of a pulmonary artery, is a rare congenital anomaly that may occur as an isolated lesion or in association with other congenital cardiovascular abnormalities. Diagnosis of associated lesions is imperative as early detection and intervention may significantly improve the patient's prognosis. We present the case of an adult patient who had come to our attention after suffering neurological decompression illness related to scuba diving. The patient's cardiopulmonary anatomy was evaluated using MRI gated spin echo, cine, and breath-held fast spoiled recalled echo sequences.

Adult↗
PubMedDate not supplied

3D phase contrast EPI MR angiography of the carotid arteries.

OBJECTIVE: Our goal was to compare 3D phase contrast (PC) echo planar imaging (EPI) MRA of the carotid and vertebral arteries with conventional 3D PC in volunteers and patients. MATERIALS AND METHODS: The carotid arteries of 12 volunteers were imaged with conventional and EPI 3D PC sequences. The visibility for each of seven carotid and four vertebral segments was qualitatively assessed. Signal intensity and homogeneity determinations were performed on the source images. Three patients with known carotid artery disease were also imaged with the same protocol. RESULTS: EPI reduced 3D PC data acquisition time from 459 to 32 s (factor of 15). Both techniques permitted full assessment of the common carotid artery, the bifurcation, as well as the proximal internal carotid artery (ICA), external carotid artery (ECA), and vertebral arteries. Visualization of the distal ICA/ECA and vertebral arteries was inferior with EPI compared with the conventional acquisition. In all patients, lesions as established by X-ray angiography were seen to equal advantage with both techniques. CONCLUSION: EPI 3D PC MRA renders diagnostic images of the proximal carotid system. The considerable reduction in data acquisition time must be weighed against poorer image quality.

Adult↗
PubMedDate not supplied

Virtual MR angioscopy of the pulmonary artery tree.

An optimized, contrast-enhanced 3D MR angiography sequence is combined with image postprocessing to render interior views of the pulmonary arteries. Virtual angioscopy was successfully demonstrated on both a healthy volunteer and a pulmonary embolism patient. By targeting selected pulmonary artery branches, virtual angioscopy has the potential to become a powerful adjunct to the use of reformatted sections and maximum intensity projections in the assessment of pulmonary embolism.

Angioscopy↗
PubMedDate not supplied

Primary angiosarcoma of the pulmonary arteries: dynamic contrast-enhanced MRI.

PURPOSE: Our goal was to assess the MR appearance and histologic correlation of primary pulmonary artery angiosarcoma. METHOD: Four patients with tumorous masses in the pulmonary arteries were evaluated by dynamic contrast-enhanced MRI using T1- and T2-weighted SE images, GE images, as well as coronal 3D MRA in breath-hold technique. The percentage of tumor enhancement was determined by measuring regions of interest before and after Gd-DTPA administration on the 2D multiplanar spoiled GRE images. RESULTS: All four masses showed some contrast enhancement on the dynamically acquired GRE images. The degree of contrast enhancement correlated with the degree of tumor differentiation, content of myxoid matrix, and associated thrombus. Contrast-enhanced 3D MRA was useful for preoperative delineation of the peripheral pulmonary arteries to the subsegmental order. CONCLUSION: Dynamic contrast-enhanced 3D MRA of the pulmonary arteries can be used to delineate pulmonary arterial angiosarcomas preoperatively. Considerable variability of contrast agent uptake reflects the wide histologic behavior of these masses in differentiation from central pulmonary embolism.

Adult↗
PubMedDate not supplied

MR defecography: depiction of anorectal anatomy and pathology.

With the advent of open-configuration MR systems, enabling image acquisition in a vertical patient position, MR defecography has become possible. MR defecography permits analyses of the anorectal angle, opening of the anal canal, functioning of the puborectal muscle, and descent of the pelvic floor during defecation. The rectal walls are well delineated on the GRE images, permitting visualization of intussusceptions and rectoceles. The concomitant depiction of structures surrounding the anorectal canal is helpful in the assessment of a spastic pelvic floor and the descending perineum syndrome and in permitting visualization of enteroceles. Dynamic MR defecography is an attractive alternative in the evaluation of defecation disorders.

Adult↗
PubMedDate not supplied

Postprocessing techniques for gadolinium-enhanced three-dimensional MR angiography.

Contrast material-enhanced three-dimensional (3D) magnetic resonance (MR) angiography is rapidly gaining acceptance as a versatile noninvasive alternative to conventional angiography. The technique has proved useful in the visualization and assessment of complex pathologic entities in the thoracic and abdominal aorta, renal arteries, pelvic arterial system, and pulmonary arteries. Several postprocessing techniques are available for reformation of the imaging data, including maximum intensity projection (MIP), surface rendering, and virtual intraluminal endoscopy (VIE). MIP and subvolume MIP reconstructions can be produced quickly and are useful for demonstration and archiving purposes. Because of its unique ability to display vessels without overlap, surface rendering is especially useful in depicting diseases that influence either the outer shape of the vessels or their topographic arrangement. VIE allows assessment of the inside of the vascular wall and is helpful in detecting wall-bound thrombus and evaluating the degree of stenosis. Most clinically relevant questions (eg, presence of pulmonary embolism, aortic aneurysm, renal artery stenosis) can be fully answered if analysis is based on MIP and thin multiplanar reformations of contrast-enhanced 3D MR angiograms. In some cases, the use of additional postprocessing techniques enhances diagnostic confidence.

Aorta↗