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J F Debatin

Publications and source records attributed to J F Debatin.

At least 91 records · Page 5Linked to original sources
PubMed1999

Three-dimensional MR angiography of a nitinol-based abdominal aortic stent graft: assessment of heating and imaging characteristics.

OBJECTIVE: To assess heating- and 3D MRA imaging characteristics of a commonly used aortic stent graft in a 1.5T MR-environment. MATERIALS AND METHODS: A bifurcated stent graft (Vanguard; Boston Scientific, Oakland, N. J.) was evaluated in vitro regarding localized heating effects as well as imaging appearance using fast 3D GRE sequences. To quantitate stent related artifacts, stent wall thickness and luminal diameters were measured. Subsequently eight patients were imaged three months following placement of an aortic stentgraft with 3D MRA. Images were assessed for the presence of stent leaks, luminal patency, and stent configuration. RESULTS: There were no temperature changes associated with the stent during scanning. Wall thickness measurements overestimated true stent thickness, resulting in minimal underestimation of luminal diameters on 3D MRA images. In vivo imaging confirmed these results. Stent patency was confirmed in all 8 patients. CONCLUSION: Contrast-enhanced 3D MRA appears well suited for the evaluation of the abdominal and pelvic vasculature following aortic implantation of a Vanguard stent.

Aged↗
PubMed1999

Clinical value of pelvic and penile magnetic resonance angiography in preoperative evaluation of penile revascularization.

Penile angiography is invasive, costly and requires postinterventional surveillance. The aim of this pilot study was to determine whether three dimensional magnetic resonance (3D-MR)-angiography may replace conventional penile angiography in preoperative planning of penile revascularization. Twelve patients with a mean age of 39 (21-59) y were evaluated. All patients underwent evaluation with intracavernous pharmacotesting, color Doppler sonography (CDS), digital subtraction angiography (DSA) and pelvic MR-angiography with gadolinium diethylene-triaminepentaacetic acid (Gd-Dota) 0.2-0.3 mmol/kg body weight. MR-angiography demonstrated the anatomy of the internal iliac arteries in 9 out of 12 patients. Intrapenile vessels were visible in 7 out of 12 patients. In comparison DSA provided complete visualization of all pelvic and penile vessels. Relevant arterial obstruction was found in 10 out of 12 patients. CDS revealed a mean maximal arterial flow of 27 (22-40) cm/s and showed in accordance to angiography arterial insuffiency in 10 out of 12 cases. Indication for revascularization could have been based on MR-angiography alone in only one patient. Therefore, selective penile angiography remains the 'gold standard' for preoperative planning of revascularization procedures.

Adult↗
PubMed1999

Characterization of renal artery stenoses based on magnetic resonance renal flow and volume measurements.

BACKGROUND: The benefits of percutaneous angioplasty of renal artery stenosis is not known. In an attempt to better define the patient subgroup most likely to benefit from a revascularization procedure, the relationship between renal arterial morphology, blood flow volume, and renal volume was investigated using magnetic resonance (MR) techniques. METHODS: Analysis was based on arterial flow volume and renal volume measurements of 130 kidneys in 65 patients with clinically suspected renal vascular disease. Significant renal arterial stenosis (RAS), documented by contrast-enhanced three-dimensional MR angiography, compromised blood supply to 31 kidneys. Renal volume measurements were related to the body mass index to derive the renal volume index (RVI). The RVI of 72 kidneys in 36 patients without evidence of RAS or severe renal insufficiency was used as a standard of reference to differentiate normal-volume from reduced-volume kidneys. RESULTS: Eighteen out of 31 RAS kidneys were significantly reduced in volume (3.08 +/- 0.75); the volume of the remaining 13 kidneys was within one standard deviation of the normal reference value. Flow volumes in kidneys with RAS were significantly reduced compared with kidneys without RAS (91.56 vs. 279.15 ml/min). Based on the RFI values (RFI = flow volume/renal volume), there was only minimal overlap between normal volume kidneys with RAS (0.73 +/- 0.34) and kidneys without RAS (2.02 +/- 0.59). RFI values of small volume kidneys with RAS (1.55 +/- 0.47), on the other hand, overlapped with both groups. CONCLUSIONS: Normal volume kidneys with impaired arterial flow caused by RAS can be differentiated from those without based on a flow index (RFI). These data suggest the existence of a critical cut-off value (flow index <1.2 ml/min per cm3 of renal tissue) beyond which the renal parenchyma starts shrinking.

Adult↗
PubMed1999

Virtual colonography.

Cross-sectional imaging techniques are increasingly being considered as alternative imaging modalities for colorectal screening. While CT-colonography uses air to insufflate the colon, an enema containing small amounts of paramagnetic contrast represents the basis for MR-colonography. Both techniques provide large three-dimensional data sets of the abdomen, containing the entire colon. Using sophisticated post-processing, the colon can be assessed in any desirable plane from various viewpoints. Thus even virtual endoscopic views can be rendered to assess the inside of the colon. This chapter briefly describes the technical aspects underlying both CT- and MR-colonography. Advantages and disadvantages of the two techniques are critically discussed, comparing them with one another as well as with conventional colonoscopy and barium enema.

Colonoscopy↗
PubMed1999

Assessment of peritoneal tolerance of a new MR blood pool contrast agent in rabbits.

OBJECTIVE: Fast 3D MR angiography in conjunction with a new blood pool contrast agent (iron oxide crystals) is a recently described method for detection and localization of intra-abdominal bleeding sites with high sensitivity and specificity. However, peritoneal reactions to the contrast agent have not yet been investigated. The purpose of this study was to assess the peritoneal tolerance of the contrast agent in an animal experiment. METHODS: Eleven rabbits were intraperitoneally injected with 5 mL diluted NC100150 Injection; two rabbits were used as the control group. Rabbits injected with NC100150 Injection were imaged in pairs at 12, 24, and 48 hours and 3 weeks, and a single rabbit was imaged at 72 hours and 1 and 2 weeks after the intraperitoneal administration of the agent. Immediately after imaging, the rabbits were killed and an autopsy was performed. Samples of peritoneal surfaces and intra-abdominal organs were harvested for histology. MR imaging, gross pathology, and histology were evaluated. RESULTS: MR imaging and gross pathology demonstrated the presence of intraperitoneal contrast agent up to 24 hours after administration. Histology revealed a considerable amount of iron in the peritoneum, mesenteric fat, and lymph nodes within the first 24 hours. In most cases, iron was rapidly cleared from these sites within 2 days; in one animal, however, iron was detectable up to 1 week. No signs of inflammation or fibrosis were detected. CONCLUSIONS: This study shows no evidence of inflammatory reactions or signs of fibrosis after the intraperitoneal application of NC100150 Injection.

Animals↗
PubMed1999

Magnetic resonance: evaluation of adrenal lesions.

Magnetic resonance imaging provides a detailed display of adrenal anatomy. The development of new imaging sequences, especially chemical shift imaging, has vastly enhanced the specificity of magnetic resonance imaging. This review outlines current magnetic resonance imaging strategies for assessing disease affecting the adrenal glands. Particular emphasis is placed on the characterization of adrenal masses.

Adrenal Gland Diseases↗
PubMed1999

Comparison of three dimensional magnetic resonance imaging in conjunction with a blood pool contrast agent and nuclear scintigraphy for the detection of experimentally induced gastrointestinal bleeding.

BACKGROUND AND AIMS: To compare the performance of 3D magnetic resonance imaging (MRI) in conjunction with an intravascular contrast agent with that of scintigraphy, with respect to detection and localisation of gastrointestinal haemorrhage in vivo in pigs. METHODS: Intraluminal bleeding sites were surgically created in the small bowel and colon of six pigs. The animals underwent scintigraphy with (99m)Tc labelled red blood cells and 3D MRI following administration of an intravascular contrast agent (NC100150) at five minute intervals over 30 minutes. For analysis, the intestinal tract was divided into six segments. Based on the two evaluated methods, each segment was characterised on a five point scale regarding the presence of a bleed. At autopsy, the surgically manipulated bowel segments were inspected for the presence of haemorrhage. RESULTS: Bleeding was confirmed at autopsy in 18/36 segments. Contrast extravasation with subsequent movement through the bowel could be documented on MRI data sets. All segments were correctly characterised, resulting in 100% sensitivity and specificity for MRI. Based on scintigraphy, interpretation of seven segments (19%) was false (sensitivity/specificity of 78%/72%). Differences in diagnostic performance were evident in the receiver operator characteristic (ROC) analysis, with an area under the MRI curve of 0.99 and under the scintigraphy curve of 0.85. CONCLUSION: In conjunction with an intravascular contrast agent, 3D MRI permits accurate detection and localisation of gastrointestinal bleeding. The extent and evolution of intestinal bleeding can be determined with repeated data acquisition.

Animals↗
PubMed1999

Plain and covered stent-grafts: in vitro evaluation of characteristics at three-dimensional MR angiography.

PURPOSE: To evaluate the characteristics of various plain and covered stents as regards demonstration of the contained lumen with simulated contrast material-enhanced fast three-dimensional (3D) magnetic resonance (MR) angiography. MATERIALS AND METHODS: Six stents (Easy Wallstent, Cragg, Palmaz, Cragg EndoPro System 1, Corvita, Passager) were implanted in plastic tubes and integrated into a closed-tubing circuit driven by a pulsatile roller flow pump. The circulating water was spiked with gadopentetate dimeglumine. Three-dimensional MR angiograms were obtained with an echo time of 1.4 or 2.1 msec and with partial (0.5 signal acquired) or full (one signal acquired) k-space sampling. The size of the stent-associated artifact was determined relative to the tube diameter. RESULTS: The Easy Wallstent and Palmaz stent caused complete obliteration of the stent lumen with all sequences. The Cragg, Cragg EndoPro System 1, and Passager stents allowed good visualization of the stent lumen. The Corvita stent demonstrated major artifacts. The magnitude of the stent-associated artifact was related to the echo time (P < .01) but not to the type of k-space sampling (P = .35). CONCLUSION: The luminal patency of selected plain and covered stents can be assessed with contrast-enhanced 3D MR angiography.

Blood Vessels↗
PubMed1999

MR colonography: optimized enema composition.

Manganese chloride, iron glycerophosphate, and cellulose additive were assessed as base materials for use in a T1-shortening single contrast enema for magnetic resonance (MR) colonography. Contrast-to-noise ratios (CNRs) were compared to those with the standard 10 mmol/L gadolinium-based enema. On T1-weighted three-dimensional gradient-recalled-echo images, CNRs with the iron glycerophosphate enema exceeded those with the manganese- and gadolinium-based enemas. Use of an additive of 0.8% wt/wt cellulose was found to be practicable as it increased viscosity sufficiently without altering CNR. The gadolinium-based enema can be replaced with an iron glycerophosphate enema to render MR colonography less costly.

Adult↗
PubMed1999

Magnetic resonance angiography versus duplex sonography for diagnosing renovascular disease.

Noninvasive testing for renovascular disease is required to identify patients who may benefit from revascularization procedures without exposing an unnecessary amount of patients to the risks of catheter angiography. All available methods of diagnosing renal artery stenosis have significant limitations. We compared a new technique, contrast-enhanced magnetic resonance angiography, with an established technique, duplex ultrasonography, for the detection of renal artery stenosis using catheter angiography as the standard of reference. Eighty-nine patients with clinically suspected renovascular disease underwent duplex renal scanning and contrast-enhanced magnetic resonance angiography. Sixty of these also underwent catheter angiography. All studies were interpreted for the presence of renal artery stenosis blinded to the results of the other imaging modalities. For detection of hemodynamically significant (>/=60% diameter reduction) main renal artery stenosis, sensitivity and specificity were 90% and 86%, respectively, for magnetic resonance angiography and 81% and 87% for duplex sonography. Most false readings involved differential grading of stenoses detected with all 3 techniques. When patients with fibromuscular dysplasia were excluded from the analysis, the sensitivity of magnetic resonance angiography increased to 97%, with a negative predictive value of 98%. Magnetic resonance angiography detected 96% and duplex 5% of accessory renal arteries seen at catheter angiography. Contrast-enhanced magnetic resonance angiography is a useful technique for diagnosing atherosclerotic renovascular disease. It overcomes the major limitations of duplex renal scanning. However, duplex has the advantage of providing hemodynamic information and appears better suited for the assessment of patients with suspected fibromuscular dysplasia.

Adult↗
PubMed1999

[Contrast-enhanced 3D MR-angiography of the thorax, abdomen and lower extremities].

Contrast-enhanced 3D MR angiography permits comprehensive assessment of the arterial system in the chest, abdomen und lower extremities. The method combines intravenous bolus application of a non-nephrotoxic, paramagnetic, extracellular contrast agent with the acquisition of a fast 3D data set. High contrast between the vascular lumen and surrounding tissues, inherent three-dimensionality and the ability to collect image data in the chest and abdomen under apnea conditions all contribute to excellent image quality. Contrast-enhanced 3D MRA is being employed in many centers throughout the world for the evaluation of various arterial pathologies. This review provides a technical overview and critically discusses the clinical applications in the chest, abdomen and lower extremities based upon the available literature and several clinical examples.

Aorta, Abdominal↗
PubMed1999

Virtual endoscopy in abdominal MR imaging.

As illustrated in this review, the diagnostic utility of VIE is highly dependent on the individual application. Virtual intraluminal endoscopy does not alter the informational content of the data set; rather, the data is presented in a different manner. In view of the considerable time requirements still associated with the VIE rendering process, the additional diagnostic value gained by VIE must be determined for each of the potential applications. Thus VIE was shown to be of no additional value in the assessment of 3D MR angiographic data sets of the abdominal aorta and renal arteries. For MR colonography, on the other hand, in vitro experiments as well as in vivo experience have demonstrated a vast diagnostic value as a primary screen supplemented by detailed analysis of reformatted images in all three orthogonal axes. In summary, virtual intraluminal imaging is a powerful tool for exploring 3D MR data sets of various abdominal structures from a different perspective. Clearly much more work is required to determine its diagnostic utility relative to its cost.

Abdomen↗
PubMed1998

[Clinical use of contrast-enhanced MR angiography].

Compared to other non-invasive MR-angiography techniques, contrast-enhanced MR angiography is a robust imaging technique in the assessment of the arterial vascular system. This is due to the use of three-dimensional data acquisition, non-nephrotoxic paramagnetic contrast and short acquisition times. Clinical applications include the evaluation of the thoracic and abdominal arterial vessels. With the refinement of this technique also small peripheral arteries of the extremities can be imaged and an entire non-invasive diagnostic work-up of the peripheral arteries will be possible.

Contrast Media↗
PubMed1998

Tissue-independent MR tracking of invasive devices with an internal signal source.

An improved MR tracking coil design is described that provides more robust tracking performance. It is shown theoretically and experimentally that a coil equipped with an internal spin source increases the signal-to-noise ratio in comparison to a coil system without internal source. The tracking behavior is stable even in air, which is important for laparoscopic work, in which the device has to be placed inside the inflated abdomen. Two types of coil windings were tested: one with the windings perpendicular to the coil axis and the other one with the windings tilted relative to this axis. The experiments showed no significant effect on the signal-to-noise ratio between the two types. The improved MR-tracking coil design with internal source was successfully used in cholecystostomies and in laparoscopic interventions; both procedures were performed on swine.

Animals↗
PubMed1998

[Vascular applications of interventional MRI].

The flow sensitivity inherent to the MR experiment allows for the non-invasive assessment of both the arterial and venous vasculature in any desired plane with good spatial resolution. Data can be acquired in a three-dimensional form, permitting reformating in any plane. In addition, MRI is capable of providing quantitative blood flow information with the use of phase-contrast flow-mapping techniques. Ultrafast gradient echo and echoplanar data acquisition strategies even permit imaging in near-real time. The availability of open MRI configurations now permits one to take advantage of the unique imaging features inherent to MR imaging for the purpose of guidance and control of various intravascular procedures. With the recent development of the MR tracking and MR profiling techniques, permitting visualization of guide-wires and catheters relative to their surroundings in the MR environment in real time, one of the last obstacles to 'Interventional MR angiography' has in effect been overcome. In addition, MR catheters can be modified to acquire high-resolution MR images of the vascular wall, thereby opening vast possibilities regarding characterization of atherosclerotic plaques. This review introduces the underlying techniques for catheter and guide-wire visualization in the MR environment, describes preliminary interventions in animals and humans and discusses the potential of intravascular MRI.

Echo-Planar Imaging↗
PubMed1998

Detection of breast cancer with conventional mammography and contrast-enhanced MR imaging.

The aim of this study was to compare the diagnostic performance of conventional mammography and dynamic contrast-enhanced fast 3D gradient-echo (GRE) MRI regarding the detection and characterization of breast lesions relative to histopathologic analysis and to assess the results of a combined evaluation of both methods. fifty consecutive patients with 63 histopathologically verified breast lesions underwent dynamic contrast-enhanced GRE MRI in addition to routine conventional mammography. All lesions were classified by both methods on a five-point scale as benign or malignant, and the results were correlated to histopathology. Conventional mammography and dynamic MRI yielded a sensitivity and specificity of 82 and 64 %, and 92 and 76 %, respectively. The difference between the results was statistically not significant (p > 0.05) with areas under the receiver-operating-characteristics curves of 0.807 for mammography and 0.906 for MR imaging. Combination of the results of both methods slightly increased the sensitivity for detection of breast cancer to 95 % but decreased specificity to 52 %. In this selected patient subset, including only patients referred for excisional biopsy, contrast-enhanced dynamic MRI proved more sensitive and specific than conventional mammography regarding the detection of malignancy. While a combination of both methods yields a slightly improved sensitivity, specificity is vastly reduced.

Adult↗