Biomedical subjects

Jochen Textor

Publications and source records attributed to Jochen Textor.

5 recordsLinked to original sources

PubMed2005

Sensitivity encoding for diffusion-weighted MR imaging at 3.0 T: intraindividual comparative study.

PURPOSE: To prospectively evaluate whether diffusion-weighted (DW) magnetic resonance (MR) imaging with sensitivity encoding (SENSE) at 3.0 T can help to improve image quality and confidence in and accuracy of diagnosis of ischemic lesions, compared with DW MR imaging with conventional phase encoding, in patients. MATERIALS AND METHODS: Patients provided informed consent after the study had been explained, and the institutional review board approved the study protocol. Eighty-five patients (46 male and 39 female patients; age range, 13-86 years; mean age, 52 years) underwent single-shot spin-echo echo-planar DW MR imaging at 3.0 T twice, in a randomized order: once with conventional phase encoding (repetition time msec/echo time msec, 4283/79) and once with SENSE (3141/69, with a reduction factor of three). With both, 128 x 128 matrix, 24 4-mm-thick sections, and two b values of 0 and 1000 sec/mm(2) were used. An eight-element SENSE-compatible receive-only surface coil was used; the built-in body coil served for radiofrequency transmission and generation of the coil sensitivity profile. SENSE and conventional phase encoding were compared for image quality, signal-to-noise ratio, relative signal intensity (SI), and lesion contrast. Two neuroradiologists read images. Diagnostic accuracy of and confidence in detection of apparent diffusion coefficient (ADC) lesions with conventional phase encoding and SENSE at MR imaging were compared; matched-pairs Wilcoxon signed rank test was used to test statistical significance. RESULTS: No major SENSE-related artifacts were seen. At MR imaging with SENSE, consistently and significantly (P < .001) higher image quality scores were achieved because of substantial reduction of image distortions and blurring. Lesion contrast was equivalent with both techniques. Diagnostic confidence for demonstration and exclusion of lesions was significantly (P < .001) higher at MR imaging with SENSE. In three patients, small microembolic lesions were only prospectively diagnosed at MR imaging with SENSE, whereas they were masked by adjacent susceptibility effects and therefore overlooked at MR imaging with conventional phase encoding. CONCLUSION: Parallel MR imaging with SENSE is feasible at 3.0 T. It significantly improves image quality, particularly by reducing or even preventing susceptibility-induced SI changes and image blurring. There was a significantly improved diagnostic confidence with which ADC changes were identified or excluded.

Adolescent↗

PubMed2004

Acute and subacute ischemic stroke at high-field-strength (3.0-T) diffusion-weighted MR imaging: intraindividual comparative study.

PURPOSE: To compare signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), image quality, and confidence in diagnosis between 1.5- and 3.0-T diffusion-weighted (DW) magnetic resonance (MR) imaging of ischemic stroke lesions. MATERIALS AND METHODS: The study design was approved by the institutional review board, and all patients gave informed consent. In a prospective intraindividual study, 25 patients who had clinical symptoms consistent with ischemic stroke underwent DW MR imaging at both 1.5 T and 3.0 T. The 3.0- or 1.5-T examination was performed immediately one after the other, in random order. Two readers in consensus recorded the presence and number of ischemic lesions and rated image quality and lesion conspicuity. The image SNR and the CNR of the ischemic lesions were quantified. Paired Student t and Wilcoxon matched-pairs signed rank tests were used to test for statistical significance. RESULTS: Image quality at 3.0-T DW MR imaging was consistently lower than that at 1.5-T DW MR imaging owing to greater image distortions (P < .05). Yet, overall SNR and lesion CNR at 3.0 T increased significantly; mean increases were 48.8% (P < .001) and 96.3% (P < .01), respectively. The higher overall SNR and lesion CNR translated into a significantly higher sensitivity in the detection of ischemic lesions at 3.0 T than at 1.5 T. Of the total of 48 lesions that were identified in 19 of the 25 patients, 47 (98%) were diagnosed at 3.0 T and 36 (75%) were diagnosed at 1.5 T. In addition, the conspicuity of the lesions that were visible with both systems was significantly higher at 3.0 T (P < .001). CONCLUSION: Although 3.0-T DW MR imaging generates greater image distortions, it yields increased SNR and CNR compared with DW MR imaging at 1.5 T. The increased CNR at 3.0 T translates into a significantly improved diagnostic confidence in the detection of focal apparent diffusion coefficient changes in the setting of subacute and acute ischemic stroke.

Acute Disease↗

PubMed2002

Prospective evaluation of a clinical score for 60-day mortality after transjugular intrahepatic portosystemic stent-shunt: Bonn TIPSS early mortality analysis.

OBJECTIVE: Transjugular intrahepatic portosystemic stent-shunt (TIPSS) is increasingly used to treat complications of portal hypertension, but proven tools for risk assessment of early mortality are lacking. DESIGN: The prospective evaluation of a new 60-day mortality score. PATIENTS AND METHODS: In a tertiary medical centre, 30 consecutive TIPSS patients were analysed for early mortality predictors, such as Child-Pugh score, TIPSS urgency (elective: > or = 36 h or emergency: < 36 h after variceal bleeding), comorbidity (Acute Physiology and Chronic Health Evaluation [APACHE]-II) and clinical data. Main predictors (P< 0.01) in this group (group-1: Child-Pugh score 10A, 10B, 10C) were graded (1, 2 or 3 points representing low, medium and high risk, respectively) and summarized as a Bonn TIPSS early mortality (BOTEM) score. This score was then tested prospectively in the next 73 TIPSS patients (group-2: Child-Pugh score 14A, 42B, 17C). RESULTS: Group 1 early mortality (30%) depended primarily on bilirubin (P< 0.005), APACHE-II (P < 0.001) and TIPSS urgency (P< 0.001). Added risk points (1, 2, 3) for bilirubin (< 3 mg/dl, 3-6 mg/dl, > 6 mg/dl, respectively), APACHE-II (< 10, 10-20, > 20 points, respectively) and urgency (elective, emergency, active bleeding, respectively) represented individual BOTEM score points. BOTEM was the best mortality predictor (P< 0.001); < or = / > 6 score points was the optimal cut-off, with 56% sensitivity, 100% specificity, 100% positive predictive value, 84% negative predictive value and 87% accuracy. In group 2, early mortality (8.2%) was again best predicted by BOTEM (P < 0.01) with the same cut-off and 67% sensitivity, 99% specificity, 80% positive predictive value, 97% negative predictive value and 96% accuracy. CONCLUSION: BOTEM score based on bilirubin, comorbidity and TIPSS-urgency predicts rather reliably post-TIPSS 60-day mortality and might optimize TIPSS treatment.

Aged↗

PubMed2002

Hepatocellular carcinoma: detection with gadolinium- and ferumoxides-enhanced MR imaging of the liver.

PURPOSE: To test the hypothesis that the accuracy of gadolinium- and ferumoxides-enhanced magnetic resonance (MR) imaging is different in small (< or =1.5-cm) and large (>1.5-cm) hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: Forty-three consecutive patients with chronic liver disease were enrolled in this study. The imaging protocol included unenhanced breath-hold T1-weighted fast field-echo sequences, unenhanced respiratory-triggered T2-weighted turbo spin-echo (SE) sequences, dynamic gadolinium-enhanced T1-weighted three-dimensional turbo field-echo sequences, and ferumoxides-enhanced T2-weighted turbo SE sequences. Images of each sequence and two sets of sequences (ferumoxides set and gadolinium set) were reviewed by four observers. The ferumoxides set included unenhanced T1- and T2-weighted images and ferumoxides-enhanced T2-weighted turbo SE MR images. The gadolinium set included unenhanced T1- and T2-weighted images and dynamic gadolinium-enhanced three-dimensional turbo field-echo MR images. In receiver operating characteristic (ROC) curve analysis, the sensitivity and accuracy of the sequences were compared in regard to the detection of all, small, and large HCCs. RESULTS: Imaging performance was different with gadolinium- and ferumoxides-enhanced images in the detection of small and large HCCs. For detection of small HCCs, the sensitivity and accuracy with unenhanced and gadolinium-enhanced imaging (gadolinium set) were significantly (P =.017) superior to those with unenhanced and ferumoxides-enhanced imaging (ferumoxides set). The area under the composite ROC curves, or A(z), for the gadolinium set and the ferumoxides set was 0.97 and 0.81, respectively. For large HCC, the ferumoxides set was superior compared with the gadolinium set, but this difference was not statistically significant. Analysis of all HCCs demonstrated no significant differences for gadolinium- and ferumoxides-enhanced imaging. CONCLUSION: For the detection of early HCC, gadolinium-enhanced MR imaging is preferred to ferumoxides-enhanced MR imaging because the former demonstrated significantly greater accuracy in the detection of small HCCs.

Adult↗

PubMedDate not supplied

Transjugular portal venous stenting in inflammatory extrahepatic portal vein stenosis.

We report the case of a 37-year-old man with necrotizing pancreatitis associated with inflammatory extrahepatic portal vein stenosis and progressive ascites. Four months after the acute onset, when no signs of infection were present, portal decompression was performed to treat refractory ascites. Transjugular transhepatic venoplasty failed to dilate the stenosis in the extrahepatic portion of the portal vein sufficiently. Therefore a Wallstent was implanted, resulting in almost normal diameter of the vessel. In follow-up imaging studies the stent and the portal vein were still patent 12 months after the intervention and total resolution of the ascites was observed.

Adult↗