Biomedical subjects

Dominik Weishaupt

Publications and source records attributed to Dominik Weishaupt.

At least 55 records · Page 3Linked to original sources

PubMed2004

Uptake of 18F-fluorocholine, 18F-fluoroethyl-L-tyrosine, and 18F-FDG in acute cerebral radiation injury in the rat: implications for separation of radiation necrosis from tumor recurrence.

UNLABELLED: Differentiation between posttherapy radiation necrosis and recurrent tumor in humans with brain tumor is still a difficult diagnostic task. The new PET tracers (18)F-fluoro-ethyl-l-tyrosine (FET) and (18)F-fluorocholine (N,N-dimethyl-N-(18)F-fluoromethyl-2-hydroxyethylammonium [FCH]) have shown promise for improving diagnostic accuracy. This study assessed uptake of these tracers in experimental radiation injury. METHODS: In a first model, circumscribed lesions were induced in the cortex of 35 rats using proton irradiation of 150 or 250 Gy. After radiation injury developed, uptake of (18)F-FET, (18)F-FCH, and (18)F-FDG was measured using autoradiography and correlated with histology and disruption of the blood-brain barrier as determined with Evans blue. In a second model, uptake of the tracers was assessed in acute cryolesions, which are characterized by the absence of inflammatory cells. RESULTS: Mean (18)F-FET, (18)F-FCH, and (18)F-FDG standardized uptake values in the most active part of the radiation lesion and the contralateral normal cortex (in parentheses) were 2.27 +/- 0.46 (1.42 +/- 0.23), 2.52 +/- 0.42 (0.61 +/- 0.12), and 6.21 +/- 1.19 (4.35 +/- 0.47). The degree of uptake of (18)F-FCH and (18)F-FDG correlated with the density of macrophages. In cryolesions, (18)F-FET uptake was similar to that in radiation lesions, and (18)F-FCH uptake was significantly reduced. CONCLUSION: Comparison of tracer accumulation in cryolesions and radiation injuries demonstrates that (18)F-FET uptake is most likely due to a disruption of the blood-brain barrier alone, whereas (18)F-FCH is additionally trapped by macrophages. Uptake of both tracers in the radiation injuries is generally lower than the published uptake in tumors, suggesting that (18)F-FET and (18)F-FCH are promising tracers for separating radiation necrosis from tumor recurrence. However, the comparability of our data with the literature is limited by factors such as different species and acquisition protocols and modalities. Thus, more studies are needed to settle this issue. Nevertheless, (18)F-FCH and (18)F-FET seem superior to (18)F-FDG for this purpose.

Acute Disease↗

PubMed2003

Thin-section CT of the lung: does electrocardiographic triggering influence diagnosis?

PURPOSE: To determine the impact of prospective electrocardiographic (ECG) triggering on image quality and diagnostic outcome of thin-section computed tomography (CT) of the lung. MATERIALS AND METHODS: Forty-five consecutive patients referred for thin-section CT of the lung were examined with prospectively ECG-triggered and nontriggered thin-section CT of the lung with a multi-detector row helical CT scanner. Subjective image quality criteria (image noise, motion artifacts, and diagnostic accessibility) were rated by three radiologists in consensus for the upper lobe, middle lobe and/or lingula, and lower lobe. Pathologic changes were assessed for the various lobes, and a diagnosis was assigned. The diagnoses were compared by two radiologists in consensus to determine the effects of CT technique on diagnostic outcome. Quantitative measurements were performed, including determination of image noise and signal-to-noise ratios in different anatomic regions. The Wilcoxon signed rank test and paired sign test (both with Bonferroni correction) were used for statistical analysis. RESULTS: Subjective assessment showed significant differences in motion artifact reduction in the middle lobe, lingula, and left lower lobe. The diagnostic assessibility of triggered CT was rated significantly higher only for the left lower lobe compared with nontriggered data acquisition. No differences in diagnostic outcome were determined between triggered and nontriggered techniques. Mean image noise in tracheal air was 68.2 +/- 17 (SD) for triggered CT versus 37.4 +/- 9 for nontriggered CT (P <.05). Mean signal-to-noise ratio in the upper versus lower lobes was 22.5 +/- 8 versus 25.4 +/- 10 for triggered and 35.6 +/- 9 versus 39.2 +/- 10 for nontriggered techniques (P <.05). CONCLUSION: Given the lack of improvement in diagnostic accuracy and the need for additional resources, ECG-triggered thin-section CT of the lung is not recommended for routine clinical practice.

Adult↗

PubMed2003

Gadobutrol-enhanced moving-table magnetic resonance angiography in patients with peripheral vascular disease: a prospective, multi-centre blinded comparison with digital subtraction angiography.

The purpose of this study was to compare moving-table three-dimensional contrast-enhanced magnetic resonance angiography (CE MRA), using 1.0-mol gadobutrol, with intra-arterial digital subtraction angiography (i.a. DSA) for evaluation of pelvic and peripheral arteries in patients with peripheral arterial occlusive disease. A total of 203 patients were examined in a prospective, multi-centre study at 1.0/1.5 T. Ten vessel segments of one leg were evaluated on-site and by three independent blinded reviewers off-site. One hundred eighty-two patients were evaluable in blinded reading. For pelvis and thigh, there was statistically significant diagnostic agreement between CE MRA and i.a. DSA on-site (94%) and off-site (86-88%). Overall, for detection of clinically significant stenoses, 93% sensitivity and 90% specificity were achieved in on-site evaluation, with 71-76 and 87-93% off-site; for detection of occlusion, sensitivity and specificity on-site were 91 and 97%, with 75-82 and 94-98% off-site. Evaluation was more sensitive on-site than off-site for detection of stenoses and occlusion, whereas specificity was similar. The CE MRA with 1.0-mol gadobutrol gave results comparable to those of i.a. DSA for the larger arteries of pelvis and thigh. Results for calf arteries were compromised by spatial resolution and technical limitations.

Angiography, Digital Subtraction↗

PubMed2003

Aortoiliac and renal arteries: prospective intraindividual comparison of contrast-enhanced three-dimensional MR angiography and multi-detector row CT angiography.

PURPOSE: To compare contrast material-enhanced three-dimensional (3D) magnetic resonance (MR) angiography and multi-detector row computed tomographic (CT) angiography in the same patients for assessment of the aortoiliac and renal arteries, with digital subtraction angiography (DSA) as the standard of reference. MATERIALS AND METHODS: DSA, 3D MR angiography, and multi-detector row CT angiography were performed in 46 consecutive patients. A total of 769 arterial segments were analyzed for arterial stenosis by using a four-point grading system. Aneurysmal changes were noted. The time required for performing 3D reconstructions and image analysis of both MR and CT data sets was measured. Patient acceptance for each modality was assessed with a visual analogue scale. Statistical analysis of data was performed. RESULTS: Sensitivity of MR angiography for detection of hemodynamically significant arterial stenosis was 92% for reader 1 and 93% for reader 2, and specificity was 100% and 99%, respectively. Sensitivity of CT angiography was 91% for reader 1 and 92% for reader 2, and specificity was 99% and 99%, respectively. Differences between the two modalities were not significant. Interobserver and intermodality agreement was excellent (kappa = 0.88-0.90). The time for performance of 3D reconstruction and image analysis of CT data sets was significantly longer than that for MR data sets (P <.001). Patient acceptance was best for CT angiography (P =.016). CONCLUSION: There is no statistically significant difference between 3D MR angiography and multi-detector row CT angiography in the detection of hemodynamically significant arterial stenosis of the aortoiliac and renal arteries.

Aged↗

PubMed2003

Morton neuroma: MR imaging in prone, supine, and upright weight-bearing body positions.

PURPOSE: To assess the effect of prone, supine, and upright weight-bearing body positions on visibility, position, shape, and size of Morton neuroma during magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eighteen patients with 20 Morton neuromas underwent MR imaging of the forefoot in prone (plantar flexion of the foot), supine (dorsiflexion of the foot), and upright weight-bearing positions. Visibility (3 = good, 2 = moderate, 1 = poor), position relative to the metatarsal bone, shape, and transverse diameter of Morton neuroma were assessed on transverse T1-weighted MR images. Associations between different body positions and variables of interest were calculated with Wilcoxon signed rank test, chi2 test, and paired Student t test. RESULTS: In the prone position, visibility of all 20 Morton neuromas was rated with a score of 3; visibility in the supine and weight-bearing positions was inferior (mean score, 2.4). All 20 (100%) Morton neuromas changed their position relative to the metatarsal bone between prone and supine and between prone and weight-bearing positions. When compared with the prone position, there was a difference in the shape of all 20 Morton neuromas in the weight-bearing position (P <.001). Between prone (mean transverse diameter of Morton neuroma, 8 mm) and supine (mean transverse diameter of Morton neuroma, 6 mm) positions, the transverse diameter of Morton neuroma significantly decreased by 2 mm (P =.03); between prone and weight-bearing positions, the decrease of the mean transverse diameter was also significant (difference, 2 mm; P =.03). CONCLUSION: Morton neuroma appears significantly different during MR imaging in prone, supine, or weight-bearing positions. The transverse diameter of Morton neuroma is significantly larger on images obtained in the prone position than it is on images obtained in the supine and upright weight-bearing positions. Visibility of Morton neuroma is best on MR images obtained in the prone position.

Adult↗

PubMed2003

Magnetic resonance imaging for the in vivo evaluation of gastric-retentive tablets.

PURPOSE: To develop a magnetic resonance imaging (MRI) technique for assessing in vivo properties of orally ingested gastric-retentive tablets under physiologic conditions. METHODS: Tablets with different floating characteristics (tablet A-C) were marked with superparamagnetic Fe3O4 particles to analyze intragastric tablet position and residence time in human volunteers. Optimal Fe3O4 concentration was determined in vitro. Intragastric release characteristic of one slow-release tablet (tablet D) was analyzed by embedding gadolinium chelates (Gd-DOTA) as a drug model into the tablet. All volunteers underwent MRI in the sitting position. Tablet performance was analyzed in terms of relative position of tablet to intragastric meal level (with 100% at meal surface), intragastric residence time (min) and Gd-DOTA distribution volume (% of meal volume). RESULTS: Intragastric tablet floating performance and residence time of tablets (tablet A-D) as well as the intragastric Gd-DOTA distribution of tablet D could be monitored using MRI. Tablet floating performance was different between the tablets (A, 93%(95 - 9%); B, 80%(80 - 68%): C, 38%(63 - 32%); p < 0.05). The intragastric distribution volume of Gd-DOTA was 19.9% proximally and 35.5% distally. CONCLUSIONS: The use of MRI allows the assessment of galenic properties of orally ingested tablets in humans in seated position.

Delayed-Action Preparations↗

PubMed2003

Magnetic resonance imaging of the weight-bearing spine.

Weight-bearing magnetic resonance (MR) imaging of the spine can either be simulated by imaging the patient in the supine position in combination with a special axial loading device or be achieved by using vertically open-configuration MR systems, which allow for in vivo MR images of the spine under upright weight-bearing conditions in either seated or standing body positions. Weight-bearing MRI of the spine permits the study of physiological as well as pathological changes in the relationships of the intervertebral disk, the spinal canal, and the neural foramina as well as the assessment of segmental instability in physiologic body positions. With this technique, MR images may be taken in painful body positions so that morphological changes of the intervertebral disk or other spinal structures may be correlated with pain or other symptoms. In selected cases, weight-bearing MRI of the spine may demonstrate clinically relevant neural compromise or foraminal stenosis, which may be occult on conventional MR images obtained in the supine position.

Humans↗

PubMed2003

Evaluation of aortoiliac aneurysm before endovascular repair: comparison of contrast-enhanced magnetic resonance angiography with multidetector row computed tomographic angiography with an automated analysis software tool.

PURPOSE: The purpose of this study was to assess accuracy and reliability of a volumetric analysis of abdominal aneurysms on the basis of multidetector row computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) with a commercially available automated vessel analysis software program. MATERIALS AND METHODS: Twenty patients with abdominal aortic aneurysms underwent preoperative CTA and MRA before endovascular repair. Postdeployment CTA was performed in 15 of these 20 patients (75%). All preoperative CTA and MRA and postdeployment CTA data sets were analyzed with an automated software tool. The length of the stent grafts on postdeployment CTA was measured and compared with the true length of the primary component. Two readers independently evaluated 13 vessel parameters on preoperative CTA and MRA, which are considered to be important in planning stent graft deployment. RESULTS: With the automated analysis software tool, all measurements could be performed on either CTA or MRA data sets. There was no statistically significant difference between postdeployment measurements of stent graft length on CTA and the true dimensions of the implanted stent grafts. Interobserver agreement for all of the measurements with either CTA or MRA was good to excellent (interclass coefficient, 0.71 to 0.99) with only minimal mean differences of measured dimensions between both readers (range, -2.0 to +2.3 mm, Bland-Altman). Intermodality agreement between CTA and MRA was good to excellent (interclass coefficient, 0.62 to 0.98) with small mean differences of measured dimensions between both methods (range, -4.1 to +2.1 mm, Bland-Altman). CONCLUSION: Volumetric measurement with an automated analysis software tool allows a fast, precise, and reliable noninvasive preoperative determination of all aortic dimensions on the basis of either CTA or MRA data sets.

Aged↗

PubMed2003

Morphologic changes and altered gene expression in an epithelioid hemangioendothelioma during a ten-year course of disease.

Epithelioid hemangioendothelioma (EHE) is a rare low-grade malignant vascular neoplasm with unpredictable prognosis. We report on a patient suffering from a vascular neoplasm with primary manifestation in the skeleton and subsequent development of lesions of EHE in the spleen, liver and lung. Based on the assumption that involvement of visceral organs was due to metastatic spread, changes in clinical behavior, morphology, and proliferation index suggest malignant progression of the tumor. Analyzing the expression of genes known to be involved in the pathogenesis of vascular tumors, we found that the appearance of less differentiated tumor was paralleled by an accumulation of TP53 and murine double minute-2 (MDM-2) protein, decreased caveolin-1 (CAV-1) expression, and increased vascular endothelial growth factor (VEGF) expression. Mutations of the von-Hippel-Lindau-tumor-suppressor-gene (VHL) were excluded as mechanism of VEGF upregulation. Therefore, we propose that the expression of TP53, MDM-2, CAV-1 and VEGF as a marker of biologic behavior be verified in a larger case study of EHE.

Arabidopsis Proteins↗

PubMed2003

Evaluation of peripheral arterial bypass grafts with multi-detector row CT angiography: comparison with duplex US and digital subtraction angiography.

PURPOSE: To assess the technical feasibility of multi-detector row computed tomographic (CT) angiography in the assessment of peripheral arterial bypass grafts and to evaluate its accuracy and reliability in the detection of graft-related complications, including graft stenosis, aneurysmal changes, and arteriovenous fistulas. MATERIALS AND METHODS: Four-channel multi-detector row CT angiography was performed in 65 consecutive patients with 85 peripheral arterial bypass grafts. Each bypass graft was divided into three segments (proximal anastomosis, course of the graft body, and distal anastomosis), resulting in 255 segments. Two readers evaluated all CT angiograms with regard to image quality and the presence of bypass graft-related abnormalities, including graft stenosis, aneurysmal changes, and arteriovenous fistulas. The results were compared with McNemar test with Bonferroni correction. CT attenuation values were recorded at five different locations from the inflow artery to the outflow artery of the bypass graft. These findings were compared with the findings at duplex ultrasonography (US) in 65 patients and the findings at conventional digital subtraction angiography (DSA) in 27. RESULTS: Image quality was rated as good or excellent in 250 (98%) and in 252 (99%) of 255 bypass segments, respectively. There was excellent agreement both between readers and between CT angiography and duplex US in the detection of graft stenosis, aneurysmal changes, and arteriovenous fistulas (kappa = 0.86-0.99). CT angiography and duplex US were compared with conventional DSA, and there was no statistically significant difference (P >.25) in sensitivity or specificity between CT angiography and duplex US for both readers for detection of hemodynamically significant bypass stenosis or occlusion, aneurysmal changes, or arteriovenous fistulas. Mean CT attenuation values ranged from 232 HU in the inflow artery to 281 HU in the outflow artery of the bypass graft. CONCLUSION: Multi-detector row CT angiography may be an accurate and reliable technique after duplex US in the assessment of peripheral arterial bypass grafts and detection of graft-related complications, including stenosis, aneurysmal changes, and arteriovenous fistulas.

Adult↗

PubMed2002

The significance of spinal canal dimensions in discriminating symptomatic from asymptomatic disc herniations.

Spinal canal dimensions are assumed to play a significant role with regard to the development of symptoms in individuals with disc herniations. The literature is inconclusive on the significance of spinal canal size as a risk factor for sciatica, mainly because of study design problems. The objective of this study, therefore, was to test the hypothesis that spinal canal dimensions are a significant risk factor for the development of sciatica, comparing symptomatic and asymptomatic individuals. Thirty symptomatic patients undergoing lumbar discectomy and 45 asymptomatic volunteers were investigated by clinical and MRI examination. The size of the spinal canal and thecal sac as well as the midsagittal spinal canal diameter were measured using a point counting method and scanner software, respectively. Differences between the groups were compared separately for each level L3/4 to L5/S1. The intra- and inter-observer error ranged between 0.95 and 0.99 for all measurements. In symptomatic patients, the dimensions of the spinal canal and thecal sac as well as the midsagittal spinal canal diameter were smaller at all disc levels. Unpaired t-test demonstrated a significant difference, ranging from P<0.05 to P<0.001. When controlled for age, sex and body height, the odds ratio for a symptomatic disc herniation increased to as high as 35, depending on the spinal level, when the size of the spinal canal was smaller than the mean for controls by two standard deviations or more. In symptomatic patients, spinal canal dimensions are significantly smaller than those in asymptomatic individuals. Spinal canal dimension is an important factor discriminating patients from control subjects. A clinically relevant grading system for disc herniation should therefore be based on the spatial relationship between herniated disc material and neurogenic structures.

Adult↗

PubMed2002

ECG-gated multi-detector row CT for assessment of mitral valve disease: initial experience.

Our objective was to evaluate applicability and image quality of contrast-enhanced, retrospectively ECG-gated multi-detector row CT (MDCT) for visualization of anatomical details of the mitral valve and its apparatus, and to determine the value of MDCT for diagnosing abnormal findings of the mitral valve. Twenty consecutive patients with mitral valve disease underwent MDCT preoperatively. Two readers assessed visibility of the mitral valve annulus, mitral valve leaflets, tendinous cords, and papillary muscles by using a four-point Likert grading scale. Abnormal mitral valve findings [thickening of the mitral valve leaflets, presence of mitral annulus calcification (MAC), and calcification of the valvular leaflets] were compared with preoperative echocardiography and intraoperative findings. Visibility of the mitral valve annulus and mitral valve leaflets was good or excellent in 15 patients (75%) and in 19 patients (95%) for papillary muscles. The MDCT yielded a 95-100% agreement compared with echocardiography and surgery with regard to the assessment of mitral valve leaflet thickening and the presence of calcifications of the mitral valve annulus or mitral valve leaflets. Intermodality agreement between MDCT and echocardiography was excellent with regard to classification of mitral valve leaflet thickness (kappa=1.00) and good regarding classification of MAC thickness (kappa=0.73). Contrast-enhanced, retrospectively ECG-gated MDCT allows good to excellent visualization of anatomical details of the mitral valve and its apparatus, and demonstrates good agreement with echocardiography and surgery in diagnosing mitral valve abnormalities.

Contrast Media↗

PubMed2002

Traumatic injuries: imaging of abdominal and pelvic injuries.

The availability of new imaging modalities has altered the diagnostic approach to patients with abdominal and pelvic trauma. Computed tomography and ultrasound have largely replaced diagnostic peritoneal lavage. Ultrasound is used in most trauma centers as the initial imaging technique for the detection of hemoperitoneum and helps to determine the need for emergency laparotomy. Computed tomography allows for an accurate diagnosis of a wide range of traumatic abdominal and pelvic conditions. The speed of single-detector helical and multi-detector row CT (MDCT) permits a rapid CT examination of the seriously ill patient in the emergency room. In particular, the technology of MDCT permits multiple, sequential CT scans to be quickly obtained in the same patient, which is a great advance in the rapid assessment of the multiple-injured patient. The evolving concepts in trauma care promoting non-operative management of liver and splenic injuries creates the need for follow-up cross-sectional imaging studies in these patients. Computed tomography and, less frequently, MR or ultrasound, are used for this purpose.

Abdominal Injuries↗

PubMed2002

Effects of iodinated contrast and field strength on gadolinium enhancement: implications for direct MR arthrography.

PURPOSE: To optimize direct magnetic resonance (MR) arthrography by determining the effect of dilution of gadolinium in iodinated contrast, saline, or albumin on T1-weighted, T2-weighted, and gradient-recalled echo (GRE) images, and the effect of scanner field strength. MATERIALS AND METHODS: Gadopentetate dimeglumine was diluted into normal saline, albumin, or iodinated contrast (0.625 mmol/liter to 40 mmol/liter). Samples were scanned at 1.5T and 0.2T. Signal intensity was measured using T1-weighted spin-echo (SE), T2-weighted SE, and two- and three-dimensional GRE (20 degrees-75 degrees flip angle) sequences. Graphical analysis of signal intensity vs. gadolinium concentration was performed. RESULTS: Albumin had no effect on gadolinium contrast. Dilution of gadolinium in iodinated contrast decreased signal intensity on all sequences compared to samples of identical concentration diluted in saline at both 1.5T and 0.2T: with a 2 mmol/liter gadolinium solution at 1.5T, signal was decreased by 26.1% on T1-weighted images, 31.7% on GRE20 images, and 28.9% on GRE45 images, and the T2 value decreased by 71.1%; at 0.2T, signal was decreased by 23.5% on T1-weighted images. On all sequences, the peak signal shifted to the left (lower gadolinium concentration) when diluted in iodinated contrast. Peak signal was also seen at different gadolinium concentrations on different sequences and field strength: at 1.5T, peak in saline/iodine was 2.5/0.625 mmol/liter on T1-weighted images, and 2.5/1.25 mmol/liter on GRE20 and GRE45 sequences. At 0.2T, peak in saline/iodine was 0.625-2.5/1.25 mmol/liter on T1-weighted images, 0.625-2.5/1.25 on GRE45 images, 2.5-10.0/1.25-5.0 mmol/liter on GRE65 images, and 1.25-5.0/0.625-1.25 mmol/liter on GRE75 images. CONCLUSION: Dilution of gadolinium in iodinated contrast results in decreased signal on T1-weighted, T2-weighted, and GRE images compared to dilution in saline or albuminfor both 1.5-T and 0.2-T scanners; if gadolinium is diluted in iodinated contrast for MR arthrography, a lower concentration should be used because the peak is shifted to the left. The use of iodinated contrast should be minimized, as it may diminish enhancement and lower the sensitivity and specificity of MR arthrography. Optimal gadolinium concentration for MR arthrography is dependent on scanner field strength and a broader range of gadolinium concentration can be used to provide maximal signal at low field strength.

Arthrography↗

PubMed2002

MR imaging of the forefoot under weight-bearing conditions: position-related changes of the neurovascular bundles and the metatarsal heads in asymptomatic volunteers.

PURPOSE: To assess practicability of weight-bearing magnetic resonance (MR) imaging of the forefoot, and to demonstrate position-related changes of the neurovascular bundles and the metatarsal heads in asymptomatic volunteers. MATERIALS AND METHODS: With an open-configuration MR system, 32 feet of 32 asymptomatic individuals aged 20-60 years were studied in supine and weight-bearing body positions. Transverse T1-weighted spin-echo MR images were performed. MR images were evaluated qualitatively with regard to image quality, visibility, and position-dependent changes of the neurovascular bundle. In addition, the position of the metatarsal heads was analyzed quantitatively. RESULTS: Weight-bearing MR imaging was feasible in all 32 feet. Quality of MR images obtained in the weight-bearing position was superior to that obtained in the supine position (P < 0.05). A change in the position of the neurovascular bundle from below a virtual line paralleling the plantar cortical line to above this line was present in 50 of 61 instances (82%) between the supine and the weight-bearing positions. When changing from the supine to the weight-bearing position, there was a significant decrease in the distance between the plantar skin and the metatarsal heads for the second (mean 4.5 mm), third (mean 4.4 mm), and fourth metatarsal heads (mean 3.7 mm) (P < 0.0001). However, the difference for the first (mean 0.5 mm) and fifth (mean 0.9 mm) metatarsal heads was not significant. CONCLUSION: Weight-bearing MR imaging of the forefoot is feasible using an open-configuration MR system and demonstrates position-related changes of the neurovascular bundles relative to the metatarsal heads, as well as position-related changes of the metatarsal heads themselves.

Adult↗

PubMed2002

Contrast-enhanced three-dimensional magnetic resonance angiography for visualization of ectopic varices.

We report the case of a 62-year-old male with portal hypertension and recurrent bleeding refractory to surgical intervention from varices in a sigmoid stoma. Although stomal varices were detected neither by physical examination, stomal endoscopy, nor duplex sonography, contrast-enhanced three-dimensional magnetic resonance angiography of the portal vein and its collateral branches demonstrated their presence. Surgical revisions of the stoma failed to prevent bleeding, but implantation of a transjugular intrahepatic shunt successfully prevented recurrent hemorrhage. This case indicates that contrast-enhanced, three-dimensional magnetic resonance angiography is useful to detect this rare complication of portal hypertension and helps to tailor adequate treatment in patients with recurrent bleeding from stomal varices.

Contrast Media↗

PubMed2002

Thoracic aorta: motion artifact reduction with retrospective and prospective electrocardiography-assisted multi-detector row CT.

The authors compared prospective (n = 20) and retrospective (n = 20) electrocardiography (ECG)-assisted multi-detector row computed tomography (CT) with non-ECG-assisted multi-detector row CT (n = 20) of the thoracic aorta with regard to reduction of motion-related artifacts. Image quality was rated for transverse source and sagittal oblique images of the thoracic aorta, including the aortic valve. ECG-assisted multi-detector row CT compared with non-ECG-assisted multi-detector row CT showed a significant reduction in motion artifacts for the entire thoracic aorta.

Adult↗

PubMed2002

Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography.

PURPOSE: To prospectively investigate the accuracy of conventional magnetic resonance (MR) imaging, direct MR arthrography, and indirect MR arthrography in assessment of possible recurrent or residual meniscal tears. MATERIALS AND METHODS: Three hundred sixty-four patients who had previously undergone meniscal preservation surgery were prospectively examined with conventional MR imaging, indirect MR arthrography, and direct MR arthrography. Ninety-four patients (104 postoperative menisci) underwent subsequent second-look arthroscopic surgery. Each case was evaluated for (a) surfacing intrameniscal intermediate- or T1-weighted signal intensity, (b) surfacing intrameniscal T2-weighted signal intensity, (c) morphologic changes beyond those expected postoperatively, (d) joint effusion on conventional MR or indirect MR arthrographic studies, and (e) overall presence or absence of recurrent meniscal tear. RESULTS: Seventy-one arthroscopically proved recurrent meniscal tears were found. In the diagnosis of recurrent meniscal tears, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 86%, 67%, 83%, 71%, and 80%, respectively, for conventional MR imaging; 83%, 78%, 90%, 64%, and 81%, respectively, for indirect MR arthrography; and 90%, 78%, 90%, 78%, and 85%, respectively, for direct MR arthrography. No significant difference in the diagnostic accuracy of one method relative to another was observed (P >.54). Surfacing intrameniscal T2-weighted signal intensity was the most specific sign, with the highest positive predictive value of a recurrent tear. CONCLUSION: Although a small incremental increase in accuracy is associated with the use of direct MR arthrography over conventional MR imaging and indirect MR arthrography, no significant difference in diagnostic accuracy among the three techniques was demonstrated for detection of recurrent or residual meniscal tear.

Adolescent↗