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Biomedical subjects

B Marincek

Publications and source records attributed to B Marincek.

At least 37 records · Page 2Linked to original sources
PubMed2001

Assessment of myocardial perfusion in coronary artery disease by magnetic resonance: a comparison with positron emission tomography and coronary angiography.

BACKGROUND: Monitoring contrast medium wash-in kinetics in hyperemic myocardium by magnetic resonance (MR) allows for the detection of stenosed coronary arteries. In this prospective study, the quality of a multislice MR approach with respect to the detection and sizing of compromised myocardium was determined and compared with positron emission tomography (PET) and quantitative coronary angiography. METHODS AND RESULTS: A total of 48 patients and healthy subjects were studied by MR using a multislice hybrid echo-planar pulse sequence for monitoring the myocardial first pass kinetics of gadolinium-diethylenetriamine pentaacetic acid bismethylamide (Omniscan; 0.1 mmol/kg injected at 3 mL/s IV) during hyperemia (dipyridamole 0.56 mg/kg). Signal intensity upslope as a measure of myocardial perfusion was calculated in 32 sectors per heart from pixelwise parametric maps in the subendocardial layer and for full wall thickness. Before coronary angiography, coronary flow reserve (hyperemia induced by dipyridamole 0.56 mg/kg) was determined in corresponding sectors by (13)N-ammonia PET. Receiver-operator characteristic analysis of subendocardial upslope data revealed a sensitivity and specificity of 91% and 94%, respectively, for the detection of coronary artery disease as defined by PET (mean coronary flow reserve minus 2SD of controls) and a sensitivity and specificity of 87% and 85%, respectively, in comparison with quantitative coronary angiography (diameter stenosis >/=50%). The number of pathological sectors per patient on PET and MR studies correlated linearly (slope, 0.94; r=0.76; P<0.0001). CONCLUSIONS: The presented MR approach reliably identifies patients with coronary artery stenoses and provides information on the amount of compromised myocardium, even when perfusion abnormalities are confined to the subendocardial layer. This modality may qualify for its clinical application in the management of coronary artery disease.

Adult↗
PubMed2001

Magnetic resonance myocardial first-pass perfusion imaging: parameter optimization for signal response and cardiac coverage.

Fast imaging techniques allow monitoring of contrast medium (CM) first-pass kinetics in a multislice mode. Employing shorter recovery times improves cardiac coverage during first-pass conditions, but potentially flattens signal response in the myocardium. The aim of this study was therefore to compare in patients with suspected coronary artery disease (CAD) two echo-planar imaging strategies yielding either extended cardiac coverage or optimized myocardial signal response (protocol A/B, six/four slices; preparation pulse, 60 degrees /90 degrees; delay time, 10/120 msec; readout flip angle, 10 degrees /50 degrees; respectively). In phantoms and myocardium of normal volunteers (N= 10) the CM-induced signal increase was 2.5-3 times higher with protocol B (P < 0.005) than with protocol A. For the detection of individually diseased coronary arteries (> or =1 stenosis with > or =50% diameter reduction on quantitative coronary angiography (QCA)), receiver-operator characteristics of protocol B (signal upslope in 32 sectors/heart) yielded a sensitivity/specificity of 82%/73%, which was superior to protocol A (P < 0.05, N= 14). For the overall detection of CAD, the sensitivity/specificity of protocol B was 85%/81%. An adequate signal response in the myocardium is crucial for a reliable detection of perfusion deficits during first-pass conditions. The presented protocol B detects CAD with a sensitivity and specificity similar to scintigraphic techniques.

Coronary Disease↗
PubMed2001

Clustered microcalcification following breast implant removal mimicking malignancy.

On mammography, clustered microcalcification can be an early and sensitive sign of malignancy, although it is also commonly seen in benign alterations of the breast. We report on a 52-year-old woman with mammographically suspicious granular calcification as a late result of a short-term silicone augmentation. Plain film, surgical, and histopathological features are demonstrated.

Breast Diseases↗
PubMed2001

Bladder outflow obstruction caused by prostate metastasis in a young male.

A 38-year-old male patient presented with symptoms of bladder outflow obstruction. Rectal palpation revealed a giant prostate. Sonography only confirmed the enlarged prostate. Magnetic resonance imaging showed, on both T1- and T2-weighted sequences, a large, inhomogenously hypointense, encapsulated prostate tumor encompassing the entire prostate. No capsular penetration or seminal vesicle invasion was seen. Transurethral biopsy of the prostate was performed. Histology demonstrated a prostate metastasis of colorectal carcinoma.

Adenocarcinoma↗
PubMed2001

Fetus and uteroplacental unit: fast MR imaging with three-dimensional reconstruction and volumetry--feasibility study.

In 22 fetuses, three-dimensional reconstruction was performed on the basis of T2-weighted magnetic resonance (MR) data sets by using a surface-rendering technique. Fetuses and uteroplacental units were segmented manually; volumes were calculated automatically. Three-dimensional reconstruction and volumetry of the fetus and uteroplacental unit are feasible with MR data sets. MR estimates correlated closely with ultrasonographic fetal biometric estimates and birth weight.

Adult↗
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↗
PubMed2000

[Proximal anastomoses of aortocoronary bypasses. Evaluation with ECG-triggered single-slice computerized tomography].

PURPOSE: Assessment of coronary artery bypass graft (CABG) patency with computed tomography methods has been demonstrated as an alternative to coronary angiography. The evaluation of the bypass anastomoses is still of limited success. Prospective ECG triggering of conventional CT scanners allows heart phase-triggered single-slice acquisition in the sub-second range. The goal of this study was to evaluate whether the use of ECG triggering can optimize the evaluation of proximal CABG anastomoses. MATERIALS AND METHODS: In ten patients after CABG surgery, ECG-triggered CT with thin (2 mm), contiguous slices was performed in the region of the proximal bypass anastomoses in the ascending aorta. The data evaluation was done on axial images and on reconstructed 2D and 3D data sets. RESULTS: The applied technique demonstrated good imaging quality, which allowed evaluation of the CABG anastomoses in all cases. Overall 18 CABG anastomoses could be visualized; 17 anastomoses could be assessed as normal, non-stenotic and patent. DISCUSSION: ECG-triggered thin-slice CT permits reliable assessment of proximal CABG anastomoses and expands the usage of CT in the evaluation of CABG.

Adult↗
PubMed2000

Acute mesenteric ischemia caused by spontaneous isolated dissection of the superior mesenteric artery: treatment by percutaneous stent placement.

Spontaneous and isolated dissection of the superior mesenteric artery is a rare and often fatal event which has been successfully treated by surgery in several reported cases. We present a patient with acute mesenteric ischemia due to superior mesenteric artery dissection who was successfully treated by percutaneous endovascular placement of a Wallstent.

Acute Disease↗
PubMed2000

Spiral CT in an acute spontaneous aorto-caval fistula.

A patient with a known infrarenal atherosclerotic aneurysm measuring 8 cm presented with sudden dyspnoe, lower back pain and enormous venous congestion of the lower extremities. Spiral CT rendered precise diagnosis and localisation of a large and acute spontaneous aorto-caval fistula and made early surgical intervention possible. Abdominal aorto-caval fistulas are rare complications and can occur after surgery, trauma or spontaneously in an atherosclerotic or inflammatory aneurysm. Spiral CT enables a rapid and precise diagnosis facilitating the planning of the therapeutic approach to this complication.

Acute Disease↗
PubMed2000

Value of (18F)-FDG positron emission tomography, computed tomography, and magnetic resonance imaging in diagnosing primary and recurrent ovarian carcinoma.

The aim of this study was to compare prospectively the accuracy of whole-body positron emission tomography (PET), CT and MRI in diagnosing primary and recurrent ovarian cancer. Nineteen patients (age range 23-76 years) were recruited with suspicious ovarian lesions at presentation (n = 8) or follow-up for recurrence (n = 11). All patients were scheduled for laparotomy and histological confirmation. Whole-body PET with FDG, contrast-enhanced spiral CT of the abdomen, including the pelvis, and MRI of the entire abdomen were performed. Each imaging study was evaluated separately. Imaging findings were correlated with histopathological diagnosis. The sensitivity, specificity and accuracy for lesion characterization in patients with suspicious ovarian lesions (n = 7) were, respectively: 100, 67 and 86% for PET; 100, 67 and 86% for CT; and 100, 100 and 100% for MRI. For the diagnosis of recurrent disease (n = 10), PET had a sensitivity of 100%, specificity of 50% and accuracy of 90%. The PET technique was the only technique which correctly identified a single transverse colon metastasis. Results for CT were 40, 50 and 43%, and for MRI 86, 100 and 89%, respectively. No statistically significant difference was seen. Neither FDG PET nor CT nor MRI can replace surgery in the detection of microscopic peritoneal disease. No statistically significant difference was observed for the investigated imaging modalities with regard to lesion characterization or detection of recurrent disease; thus, the methods are permissible alternatives. The PET technique, however, has the drawback of less accurate spatial assignment of small lesions compared with CT and MRI.

Adult↗
PubMed2000

In-vivo real-time magnetic resonance monitoring of endoscopic laser applications in the porcine gastrointestinal tract.

BACKGROUND AND STUDY AIMS: Endoscopic laser therapy involves a risk of perforation, mainly because the depth of tissue destruction is not visible. Magnetic resonance (MR) imaging is capable of showing temperature changes, and is therefore suitable for monitoring thermal therapies such as laser. This animal study assessed the feasibility of real-time MR monitoring of endoscopic laser applications in the gastrointestinal tract. MATERIALS AND METHODS: The procedures were carried out using an MR-compatible endoscope in three live pigs in a 0.5-Tesla interventional MR system. Nd:YAG laser applications were performed in the lower gastrointestinal tract (n = 7) and upper gastrointestinal tract (n = 5), and were monitored using real-time color-coded T1-weighted gradient echo sequences. The postmortem macroscopic tissue coagulation sizes were compared with the lesion diameters seen on real-time MR. RESULTS: The endoscope did not cause any artifacts during continuous MR imaging. Ten of the twelve laser lesions were visible with temperature-sensitive MR imaging, and their sizes correlated well with the diameters of the postmortem macroscopic coagulation zones (r = 0.76, P = 0.009). Two laser lesions were not visible on MR due to technical limitations inherent with the healthy animal model. CONCLUSIONS: The formation of endoscopic laser lesions in the porcine gastrointestinal tract can be accurately visualized using real-time temperature-sensitive MR imaging. This new technique has the potential to spare healthy tissue while ensuring full treatment coverage of the targeted lesion with fewer therapy sessions.

Animals↗
PubMed2000

Colonic masses: detection with MR colonography.

PURPOSE: To assess magnetic resonance (MR) colonography as a method for detection of colorectal masses, with conventional colonoscopy as the reference standard. MATERIALS AND METHODS: MR colonography was performed in 132 patients referred for colonoscopy because of the possible presence of a mass. After rectal filling with a gadopentetate dimeglumine and water enema, T1-weighted three-dimensional gradient-echo MR studies were acquired with the patient in the prone and supine positions. Water-sensitive single-shot fast spin-echo MR images were also obtained. Surface-rendered virtual endoscopic endoluminal views, orthogonal sections in three planes, and water-sensitive MR images were interactively assessed for presence of colorectal masses by two radiologists. RESULTS: MR colonography was well tolerated without sedation or analgesia. MR image quality was sufficient for diagnosis in 127 (96%) patients. Most small (</=5-mm-diameter) masses were overlooked at MR colonography, but 19 of 31 6-10-mm lesions and 26 of 27 large (>10-mm) lesions were correctly identified. For these large masses, MR colonography had a sensitivity of 93%, specificity of 99%, positive predictive value of 92%, and negative predictive value of 98% for detection of masses. CONCLUSION: MR colonography is a promising modality for help in detecting colorectal mass lesions larger than 10 mm in diameter.

Administration, Rectal↗
PubMed2000

[Ultrasound-guided biopsy of non-palpable breast lesions: correlation with the results of fine-needle aspiration biopsy].

PURPOSE: The purpose of this study was the clinical evaluation of ultrasound-guided biopsy in comparison with ultrasound-guided fine-needle aspiration biopsy of identical, non-palpable breast lesions. MATERIALS AND METHODS: From August 1997 until July 1998, 73 ultrasound-guided biopsies were performed in 66 patients with non-palpable lesions of the breast. In 18 patients (age 33-77 years) with 20 non-palpable lesions, fine-needle aspiration biopsy (20-G needle) and biopsy (18-G biopsy needle) were performed on a single occasion. This was the patient selection of our retrospective study. RESULTS: One malignant neoplasm was found among the 20 biopsied lesions, while the remaining 19 lesions were of a benign nature. In 20% of the cases, the material obtained by fine-needle biopsy was not sufficient for a cytologic diagnosis, while biopsy allowed a diagnosis in 19/20 cases. No complications were observed. CONCLUSIONS: Ultrasound-guided biopsy using an 18-G needle is a suitable method for the evaluation of non-palpable lesions that are only visible on ultrasound. It represents an attractive alternative to fine-needle aspiration in the absence of experienced cytologic diagnosticians.

Adult↗
PubMed2000

Ultrafast MR imaging of the fetus.

OBJECTIVE: We examined the capability of ultrafast single-shot fast spin-echo imaging to assess different fetal organ systems compared with prenatal sonography, using autopsy or postpartum imaging as a standard of reference. SUBJECTS AND METHODS: Thirty women with complicated pregnancies (mean age of gestation, 190 +/- 54 days) underwent T2-weighted ultrafast MR imaging. MR images were analyzed with regard to diagnostic confidence in assessing abnormalities of fetal organ systems, and data were correlated with postpartum findings or necropsy. Results were compared with those of prenatal sonography. RESULTS: Using receiver operating characteristic curve analysis, diagnostic confidence of MR imaging was best for assessing the brain (area under the curve [Az] = 0.96) and spinal canal (Az = 1.0), uteroplacental unit (Az = 0.93), and lungs (Az = 0.91). Results for the heart (Az = 0.63) and extremities (Az = 0.77) were significantly lower than that of other organs (p < 0.001). Diagnostic accuracy increased with gestational age. No statistically significant difference between sonography and MR imaging was found for the detection of abnormality in any organ system. In three fetuses, MR imaging was superior to sonography in characterizing cerebral abnormalities. MR imaging was inferior to sonography in characterizing abnormalities of the heart and extremities. CONCLUSION: Our results indicate that ultrafast MR imaging can be used for in vivo fetal imaging, especially in assessing cerebral abnormalities. However, MR imaging should be restricted to situations in which sonographic findings are ambiguous or impaired.

Congenital Abnormalities↗
PubMed1999

[Crohn's disease: evaluation with computed tomography and magnetic resonance imaging].

Computed Tomography should increasingly be used as a minimally invasive alternative to small bowel enteroclysis. Firstly, CT-examination is less stressful to the patients. Secondly, information is not only provided about the bowel lumen but in addition the thickness and architecture of the small bowel wall as well as the adjacent structures can be evaluated. Extraintestinal lesions/complications are easily diagnosed. Moreover, CT can be used as primary screening method in the evaluation of abdominal complaints of unknown origin. Next to Crohn's disease, numerous other small bowel diseases can be excluded. Magnetic resonance imaging will become another alternative imaging technique in future. Major advantages are the lack of ionizing radiation, the multiplanar scanning technique and the possibility of extensive postprocessing by virtual endoscopy.

Adolescent↗