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Biomedical subjects

J F Debatin

Publications and source records attributed to J F Debatin.

At least 55 records · Page 3Linked to original sources
PubMed2001

MR evaluation of ventricular function: true fast imaging with steady-state precession versus fast low-angle shot cine MR imaging: feasibility study.

Short- and long-axis cine magnetic resonance (MR) images were obtained with a standard fast low-angle shot, or FLASH, sequence and a first-generation true fast imaging with steady-state precession (FISP) sequence on a 1.5-T MR imager. Contrast-to-noise ratios and volumetric left ventricular measurements were compared for manual and automatic segmentation. True FISP images were associated with significantly (P<.01) higher contrast-to-noise ratios and allowed better detection of the endocardial border. True FISP images were provided with short acquisition times and excellent contrast between the myocardium and the ventricular lumen.

Adult↗
PubMed2001

Whole-body MR imaging in 30 seconds with real-time true FISP and a continuously rolling table platform: feasibility study.

A technique for whole-body magnetic resonance (MR) imaging in only 30 seconds was developed on the basis of a rolling table platform with integrated surface coils and real-time true fast imaging with steady-state precession. In five patients, all hepatic and pulmonary lesions with a diameter exceeding 8 mm were detected by using thoracic and abdominal helical computed tomography as the reference method. Whole-body MR imaging with real-time true fast imaging with steady-state precession is feasible and may be suitable for tumor screening and staging.

Adult↗
PubMed2001

Surveillance of peripheral arterial bypass grafts with three-dimensional MR angiography: comparison with digital subtraction angiography.

OBJECTIVE: The purpose of this study was to use contrast-enhanced three-dimensional MR angiography to assess the patency of peripheral arterial bypass grafts of the lower extremity. SUBJECTS AND METHODS: The study included 39 patients with 45 lower limb grafts. Twenty-eight were saphenous vein grafts, 13 were expanded polytetrafluoroethylene, and two were Dacron grafts. Digital subtraction angiography correlation was available for 30 patients (31 grafts). MR angiography was performed on a 1.5-T system with a multichannel quadrature phased array peripheral vascular coil. The scanning delay was determined with a test bolus technique, using half-time to maximum signal intensity in the graft. Arterial imaging was accomplished with two three-dimensional MR angiography acquisitions with gadopentetate dimeglumine administered using an automated injector. The pelvic and femoral arteries were imaged, the MR table was repositioned, and the lower limb arteries were imaged. The three-dimensional MR angiography sequence used the following parameters: TR/TE, 5.2/1.5 msec; inversion time, 28 msec; flip angle, 30 degrees. The proximal anastomosis, graft, and distal anastomosis were characterized as normal, stenosed, occluded, or ectatic or aneurysmatic. RESULTS: Sensitivity and specificity values for MR angiography regarding the assessment of grafts were 100% for 87 evaluable segments for which digital subtraction angiography correlation was available: stenosis (n = 10), occlusions (n = 9), ectasia or aneurysms (n = 8). Six segments could not be assessed because of the presence of intravascular stents or metallic clips. CONCLUSION: Contrast-enhanced three-dimensional MR angiography is well suited for the characterization of arterial grafts, for planning subsequent vascular interventions, and for excluding further lesions.

Aged↗
PubMed2001

Ultrafast MR imaging of the pelvic floor.

OBJECTIVE: The aim of this study was to compare pelvic floor anatomy and laxity at rest and on straining (Valsalva's maneuver) using dynamic ultrafast MR imaging in women who were continent versus those with stress incontinence differing in obstetric history. MATERIALS AND METHODS: Thirty continent women were divided into three equal groups (nulliparous, previous cesarean delivery, previous vaginal delivery) and compared with 10 women with stress-incontinence with a history of at least one vaginal delivery. MR imaging of the pelvic floor at rest and on maximal strain was performed, using axial T2-weighted fast spin-echo images followed by sagittal ultrafast T2-weighted single-shot fast spin-echo sequences. Mean population age (age range, 22-45 years; mean +/- SD, 36 +/- 5.4 years), was similar in the four groups, as was parity in the three parous groups. RESULTS: Mean distances between the bladder floor and pubococcygeal line at rest did not differ between the four groups. On straining, bladder floor descent was 1.1 +/- 0.9, 1.0 +/- 1.1, and 1.9 +/- 0.9 cm in continent nulliparous, cesarean delivery, and vaginal delivery women, respectively, versus 3.2 +/- 1.0 cm in incontinent women (p = 0.0005). Cervical descent was greater in incontinent versus nulliparous women (p = 0.0019). Bladder floor descent was greater in the continent vaginal delivery group than in continent cesarean delivery control patients (p = 0.04). In patients with stress incontinence, symptoms did not correlate with amplitude of descent. The right levator muscle was thinner overall than the left, regardless of frequency direction (p = 0.001). CONCLUSION: Ultrafast MR imaging using the T2-weighted single-shot fast spin-echo sequence allows dynamic evaluation of the pelvic compartments at maximal strain with no need for contrast medium. Pelvic floor laxity and supporting fascia abnormalities were most common in patients with stress incontinence followed by continent women with a history of vaginal delivery. The results are therefore compatible with the hypothesis of vaginal delivery as a contributory factor to stress incontinence in older parous women.

Adult↗
PubMed2001

MR colonography without colonic cleansing: a new strategy to improve patient acceptance.

OBJECTIVE: MR colonography permits accurate detection of colonic polyps larger than 8 mm. Patient acceptance remains limited because of the need for bowel cleansing. The aim of this study was to develop and assess a strategy obviating colonic cleansing by performing MR colonography in conjunction with fecal tagging based on the oral administration of barium. SUBJECTS AND METHODS: Six healthy volunteers and six patients with suspected colorectal tumors, undergoing conventional colonoscopy within 1 week of MR imaging, were included in this study. For fecal tagging, 200 mL of a barium-containing contrast agent was ingested with each of four principal meals preceding the examination. For MR colonography, the colon was filled with a barium and water mixture while gadobenate dimeglumine (0.2 mmol/kg) was injected IV. RESULTS: The combination of fecal tagging and colonic filling with barium resulted in a homogeneously low signal throughout the colonic lumen in all 12 subjects. IV injection of gadolinium caused avid enhancement of the colonic wall. Similarly, lesions arising from the colonic wall enhanced avidly. In the six evaluated patients, MR colonography correctly identified two colonic carcinomas in two patients and one polyp in each of another two patients. CONCLUSION: Fecal tagging obviates bowel cleansing and should, therefore, enhance patient acceptance for MR colonoscopy. Barium used as the tagging agent is promising because it is inexpensive, commercially available, and characterized by an excellent safety profile.

Adult↗
PubMed2000

Contrast-enhanced MR angiography in patients with aortic occlusion (Leriche syndrome).

The diagnostic utility of contrast-enhanced three-dimensional magnetic resonance angiography (3D MRA) was retrospectively evaluated in 24 patients with Leriche syndrome. 3D MRA was performed either of the abdomen alone (n = 6), the abdomen and chest (n = 2), the abdomen and lower extremities (n = 12), or of all stations (n = 4). MRA image sets were evaluated regarding the location of the aortic occlusion, the presence of concomitant occlusive disease affecting the renal and visceral arteries, the type and extent of collateralization, and the level of the most proximal graftable arterial segments. Intravenous digital subtraction angiography was available for correlation in two patients, while surgical correlation was possible in 14 patients. MRA permitted classification of the level of aortic occlusion as juxtarenal (n = 8), infrarenal, and cranial to the origin of the inferior mesenteric artery (IMA; n = 11), and infrarenal but caudad to the IMA (n = 5). Extraanatomical grafts were displayed to similar advantage as collateral parietal and visceral pathways. Contrast-enhanced 3D MRA thus appears to be well suited for assessment of patients with suspected Leriche syndrome.

Aged↗
PubMed2000

TE-switched double-contrast enhanced visualization of vascular system and instruments for MR-guided interventions.

A visualization principle for MR-guided vascular interventions based on the concerted use of two contrast agents is introduced. The first contrast agent, consisting of small paramagnetic iron oxide particles, was administered intravenously to shorten T(1), and even more so T *(2), of the blood for extended time periods. The second agent, a monomeric gadolinium complex, was added to a solution in an interventional device, such as a percutaneous-transluminal-angioplasty (PTA) balloon, to reduce T(1) with only minor additional effects on T *(2). With appropriate T(1)- and T *(2)-weighting the vascular tree (TE <3 ms) and the device (TE > or =8 ms) could be selectively imaged (TR <20 ms). Potentially, both images could be simultaneously updated in the subsecond range. Whereas a visualization of thin structures like guidewires was found to require pulse-sequence optimization, a successful visualization of a PTA balloon in a swine aorta in vivo was possible with standard sequences.

Angioplasty, Balloon, Coronary↗
PubMed2000

Interventional MRA and intravascular imaging.

Several attributes make magnetic resonance imaging (MRI) attractive for guidance of intravascular therapeutic procedures, including high soft tissue contrast, imaging in arbitrary oblique planes, lack of ionizing radiation, and the ability to provide functional information, such as flow velocity or flow volume per unit time, in conjunction with morphologic information. For MR guidance of vascular interventions to be safe, the interventionalist must be able to visualize catheters and guidewires relative to the vascular system and surrounding tissues. A number of approaches for rendering instruments visible in an MR environment have been developed, including both passive and active techniques. Passive techniques depend on contrast agents or susceptibility artifacts that enhance the appearance of the catheter in the image itself, whereas active techniques rely on supplemental hardware built into the catheter, such as a radiofrequency (RF) coil. Additionally, the ability to introduce an RF coil mounted on a catheter presents the opportunity to obtain high-resolution images of the vessel wall. These images can provide the capability to distinguish and identify various plaque components. The additional capabilities of MRI could potentially open up new applications within the purview of vascular interventions beyond those currently performed under X-ray fluoroscopic guidance.

Angioplasty, Balloon↗
PubMed2000

Interventional and intravascular MR angiography.

Magnetic resonance imaging (MRI) has a number of characteristics which make it attractive for guidance of intravascular therapeutic procedures, including high soft tissue contrast, imaging in any arbitrary oblique plane, lack of ionizing radiation, and the ability to provide functional information, such as flow velocity and volume per unit time. For MR guidance of vascular interventions to be safe, catheters and guidewires must be visualized relative to the vascular system and surrounding tissues. A number of approaches for making instruments visible in an MR environment are presented, including both passive and active techniques. Passive techniques depend on contrast agents or susceptibility artifacts, whereas active techniques, including MR tracking, MR profiling, and active field inhomogeneity, use some form of electrical coil built into the instrument. The potential for obtaining high-resolution images of the vessel wall using coils built into a catheter is also discussed. These images provide the capability to distinguish and identify various plaque components. The additional capabilities of MRI could potentially open up new applications beyond those currently performed under X-ray fluoroscopic guidance.

Angioplasty, Balloon↗
PubMed2000

[Virtual reality in MR colonography].

Early detection and subsequent removal of colorectal polyps have been shown to constitute an effective approach for decreasing the incidence of colorectal cancer. The lack of an ideal modality for colorectal polyp screening stimulated interest in the development of CT-colonography and MR-colonography. Both techniques allow the colon to be analyzed in a cross-sectional as well as a virtual endoscopic format. Causing no side-effects and not concerning for radiation exposure MR-colonography warrants further consideration. Additional to detecting polyps down to 6 mm in size the inner wall contour and the morphology of the colonic wall itself can be assessed. New developments like fecal tagging will increase patients acceptance comparing to other diagnostic techniques. In search of an ideal modality for polyp screening MR-colonography will become a potent option in the diagnostic arsenal.

Colonic Polyps↗
PubMed2000

Three-dimensional contrast-enhanced MRI using an intravascular contrast agent for detection of traumatic intra-abdominal hemorrhage and abdominal parenchymal injuries: an experimental study.

The aim of this study was to compare the performance of 3D MRI in conjunction with an intravascular contrast agent to spiral contrast-enhanced CT, regarding the detection of abdominal parenchymal injuries as well as peritoneal hemorrhage in an animal model. Liver and kidney injuries were created surgically in six female pigs under general anesthesia. All pigs underwent contrast-enhanced spiral CT and 3D MR imaging following administration of an intravascular contrast agent (NC100150 Injection). Two readers rated their confidence independently on MR and CT data sets using a five-point scale for the presence of organ injury and hemoperitoneum. Autopsy findings served as standard of reference. Sensitivity and specificity for MR in detecting hepatic and renal injuries as well as hemoperitoneum was 100%. Computed tomography was less accurate with sensitivity and specificity values of 90 and 94%, respectively. Receiver operating characteristics (ROC) analysis revealed a higher confidence when interpretation was based on MR images. In an animal model 3D MR imaging in conjunction with an intravascular contrast agent proved highly accurate in detecting and localizing parenchymal injuries to the upper abdomen as well as in detecting intraperitoneal blood collections.

Abdominal Injuries↗
PubMed2000

MR-angiography: the role of contrast agents.

Contrast-enhanced 3D MR angiography (MRA) permits comprehensive assessment of the supraaortic arteries as well as the arterial system in the chest, abdomen and lower extremities. 3D MRA combines intravenous injection of a non-nephrotoxic, paramagnetic, extracellular contrast agent that increases the signal intensity of blood by shortening its T1 value 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. This review provides clinical applications of 3D MRA in the chest, abdomen and lower extremities based upon the available literature and several clinical examples.

Aorta, Abdominal↗
PubMed2000

[Whole-body MRA on a rolling table platform (AngioSURF)].

PURPOSE: Development of a technique for whole-body MR angiography based on a rolling table platform and integration of a surface coil. MATERIAL AND METHODS: The developed rolling table platform AngioSURF (System for Unlimited Rolling Field-of-view) with integrated surface coil can be mounted on top of the original patient table of a Siemens Symphony System. Data acquisition was performed with a standard body array surface coil. The system was tested on three volunteers and one patient with angiographically documented vascular pathology. Data acquisition was performed with a 3D-FLASH-sequence (TR/TE 2.1/0.7 ms, flip angle: 20 degrees, FOV 40 x 40 cm, 80 partitions, matrix 512 x 420 with zero interpolation). Five data sets were collected in immediate succession during continuous injection of a paramagnetic contrast agent. Time of acquisition per data set was 10 seconds. Table repositioning was performed manually within 3 seconds. Thus the total acquisition time amounted to 72 seconds. RESULTS: No problems with handling occurred in any of the four cases. The excellent image quality enables detailed assessment of the displayed vascular territories. CONCLUSIONS: The rolling table platform with integrated surface coil (AngioSURF) allows diagnostic display of the arterial vascular system from supraaortic vessels to the distal trifurcation arteries in only 72 seconds.

Angiography↗
PubMed2000

Ligating clips for three-dimensional MR angiography at 1.5 T: in vitro evaluation.

Artifact size on three-dimensional (3D) magnetic resonance (MR) angiograms and safety of various vascular clips (15 titanium and three absorbable polydioxanone clips) were assessed. All evaluated clips were completely safe. Biodegradable clips rendered no artifacts; titanium clips were associated with susceptibility effects. Artifact size was dependent on clip size, clip orientation, echo time, and degree of k-space coverage. In the presence of titanium vascular clips, fast 3D MR angiography should be performed with the shortest echo time and full k-space coverage.

Artifacts↗
PubMed2000

Pelvic and lower extremity veins: contrast-enhanced three-dimensional MR venography with a dedicated vascular coil-initial experience.

PURPOSE: To assess the performance of three-dimensional (3D) magnetic resonance (MR) venography of the pelvis and lower extremities in patients without acute deep venous thrombosis by using a lower extremity vascular coil and pedal injection of paramagnetic contrast material. MATERIALS AND METHODS: Conventional and MR venography were performed in 35 legs in 25 patients referred for evaluation of varicosities (n = 8) and postthrombotic changes (n = 7) and assessment of the great saphenous veins prior to bypass surgery (n = 10). Injection of 120 mL of diluted (1:15) gadopentetate dimeglumine into a pedal vein was performed manually at a rate of 1 mL/sec, and 3D gradient-recalled echo data sets of the upper and lower veins were collected. Conventional and MR venographic images were analyzed separately in a blinded fashion. RESULTS: MR image quality was comparable to that of conventional venograms. Varicose changes of the great and small saphenous veins (sensitivity, 94% [44 of 47]; specificity, 96% [89 of 93]) were assessed as reliably as their status before bypass surgery (sensitivity, 98% [53 of 54]; specificity, 92% [47 of 51]). Postthrombotic changes were diagnosed with a sensitivity of 100% [13 of 13] and a specificity of 98% [88 of 90]. CONCLUSION: Direct 3D MR venography comprehensively displays the lower extremity venous system and permits assessment of postthrombotic and varicose changes and the bypass suitability of the saphenous vein.

Adult↗
PubMed2000

Gadopentetate dimeglumine excretion into human breast milk during lactation.

PURPOSE: To analyze the amount of gadopentetate dimeglumine excreted into human breast milk following intravenous injection of a clinical dose. MATERIALS AND METHODS: Gadopentetate dimeglumine was injected intravenously in 20 lactating women (23-38 years of age). Breast-feeding was interrupted for at least 24 hours. Serial samples of expressed milk were collected and analyzed for gadolinium concentration by means of inductively coupled plasma atomic emission spectrometry at a wavelength of 342.247 nm. RESULTS: The cumulative amount of gadolinium excreted in human breast milk during 24 hours was 0.57 micromol +/- 0.71 (SD; range, 0.05-3.0 micromol). The excreted dose was thus less than 0.04% of the administered intravenous dose (range, 0.001%-0.04%; mean, 0.009% +/- 0.010) for all cases. CONCLUSION: Less than 0.04% of administered gadopentetate dimeglumine is excreted into human breast milk. The amount transferred to a nursing infant orally would be far more than 100 times less than the permitted intravenous dose (200 micromol per kilogram of body weight) for neonates. The recommendation of a 24-hour suspension of breast-feeding for lactating women should thus be reconsidered.

Adult↗