Institute for Clinical Radiology

Germany

Institute for Clinical Radiology

Germany
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Unterrainer M.,Ludwig Maximilians University of Munich | Galldiks N.,Institute of Neuroscience and Medicine | Galldiks N.,University of Cologne | Suchorska B.,LMU | And 10 more authors.
Journal of Nuclear Medicine | Year: 2017

In patients with brain metastasis, PET using labeled amino acids has gained clinical importance, mainly regarding the differentiation of viable tumor tissue from treatment-related effects. However, there is still limited knowledge concerning the uptake characteristics in patients with newly diagnosed and untreated brain metastases. Hence, we evaluated the uptake characteristics in these patients using dynamic O-(2-18F-fluoroethyl)-L-tyrosine (18F-FET) PET. Methods: Patients with newly diagnosed brain metastases without prior local therapy and 18F-FET PET scanning were retrospectively identified in 2 centers. Static and dynamic PET parameters (maximal/mean tumor-to-brain-ratio [TBRmax/TBRmean], biologic tumor volume [BTV], and time-activity curves with minimal time to peak [TTPmin]) were evaluated and correlated with MRI parameters (maximal lesion diameter, volume of contrast enhancement) and originating primary tumor. Results: Forty-five brain metastases in 30 patients were included. Forty of 45 metastases (89%) had a TBRmax ≥ 1.6 and were classified as 18F-FET-positive (median TBRmax, 2.53 [range, 1.64-9.47]; TBRmean, 1.86 [range, 1.63-5.48]; and BTV, 3.59 mL [range, 0.04-23.98 mL], respectively). In 39 of 45 brain metastases eligible for dynamic analysis, a wide range of TTPmin was observed (median, 22.5 min; range, 4.5-47.5 min). All 18F-FET- negative metastases had a diameter of ≤ 1.0 cm, whereas metastases with a. 1.0 cm diameter all showed pathologic 18F-FET uptake, which did not correlate with lesion size. The highest variability of uptake intensity was observed within the group of melanoma metastases. Conclusion: Untreated metastases predominantly show increased 18F-FET uptake, and only a third of metastases > 1.0 cm were 18F-FET-negative, most likely because of scanner resolution and partial-volume effects. In metastases > 1.0 cm, 18F-FET uptake intensity was highly variable and independent of tumor size (even intraindividually). 18F-FET PET might provide additional information beyond the tumor extent by reflecting molecular features of a metastasis and might be a useful tool for future clinical applications, for example, response assessment. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.


Plant C.,TU Munich | Teipel S.J.,University of Rostock | Teipel S.J.,Ludwig Maximilians University of Munich | Oswald A.,Ludwig Maximilians University of Munich | And 10 more authors.
NeuroImage | Year: 2010

Subjects with mild cognitive impairment (MCI) have an increased risk to develop Alzheimer's disease (AD). Voxel-based MRI studies have demonstrated that widely distributed cortical and subcortical brain areas show atrophic changes in MCI, preceding the onset of AD-type dementia. Here we developed a novel data mining framework in combination with three different classifiers including support vector machine (SVM), Bayes statistics, and voting feature intervals (VFI) to derive a quantitative index of pattern matching for the prediction of the conversion from MCI to AD. MRI was collected in 32 AD patients, 24 MCI subjects and 18 healthy controls (HC). Nine out of 24 MCI subjects converted to AD after an average follow-up interval of 2.5 years. Using feature selection algorithms, brain regions showing the highest accuracy for the discrimination between AD and HC were identified, reaching a classification accuracy of up to 92%. The extracted AD clusters were used as a search region to extract those brain areas that are predictive of conversion to AD within MCI subjects. The most predictive brain areas included the anterior cingulate gyrus and orbitofrontal cortex. The best prediction accuracy, which was cross-validated via train-and-test, was 75% for the prediction of the conversion from MCI to AD. The present results suggest that novel multivariate methods of pattern matching reach a clinically relevant accuracy for the a priori prediction of the progression from MCI to AD. © 2009 Elsevier Inc. All rights reserved.


Rottenkolber M.,Institute of Medical Information science | Ferrari U.,Diabetes Research Group | Ferrari U.,Ludwig Maximilians University of Munich | Ferrari U.,Helmholtz Center for Environmental Research | And 34 more authors.
Journal of Clinical Endocrinology and Metabolism | Year: 2015

Context: The pathogenesis of type 2 diabetes (T2D) is still incompletely understood. In-depth phenotyping of young individuals at risk for T2D can contribute to the understanding of this process. Objective: The purpose of this study was to metabolically characterize women with recent gestational diabetes (GDM), an at-risk cohort for T2D. Study Participants: Participants were 147 women consecutively recruited 3 to 16 months after pregnancy: women who had GDM and women after a normoglycemic pregnancy (control subjects) in a 2:1 ratio. Design: This was a monocenter cross-sectional analysis (Prediction, Prevention and Subclassification of Type 2 Diabetes Study [PPS-Diab]). Methods: A 5-point oral glucose tolerance test with calculation of the insulin sensitivity index and disposition index (validation by euglycemic clamp and intravenous glucose tolerance test) was performed. In addition, anthropometrics, medical and family history, clinical chemistry and biomarkers, statistical modeling, and a magnetic resonance imaging/magnetic resonance spectroscopy substudy (body fat distribution and liver and muscle fat; n = 66) were obtained. Results: Compared with control subjects, women after GDM had a reduced disposition index, higher levels of plasma fetuin-A, and a lower insulin sensitivity index. A low insulin sensitivity index was also the major determinant of pathological glucose tolerance after GDM. The factors most strongly predictive of low insulin sensitivity were high plasma leptin, body mass index, triglycerides, and waist circumference. Ectopic lipids showed no body mass index-independent associations with having had GDM or low insulin sensitivity in a magnetic resonance imaging substudy. Conclusions: We found that β-cell function is already impaired in women with recent GDM, a young at-risk cohort for T2D. In addition, our data suggest that fetuin-A and leptin signaling may be important early contributors to the pathogenesis of T2D, at this disease stage equally or more relevant than ectopic lipids and low-grade inflammation. Copyright © 2015 by the Endocrine Society.


Raya J.G.,New York University | Raya J.G.,Institute for Clinical Radiology | Melkus G.,University of California at San Francisco | Adam-Neumair S.,Institute for Clinical Radiology | And 8 more authors.
Radiology | Year: 2013

Purpose: To assess the use of diffusion-tensor (DT) imaging of articular cartilage to detect and grade early cartilage damage in human specimens with early signs of cartilage damage. Materials and Methods: This study was approved by the institutional review board. Forty-three cartilage-on-bone samples drilled from 21 human patellae were examined with 17.6-T magnetic resonance (MR) imaging and a diffusion-weighted spinecho sequence (spatial resolution, 50 × 100 × 800 mm). Subsequently, samples underwent histologic analysis with safranin O staining. Cartilage damage on safranin O histologic slides was quantified with Osteoarthritis Research Society International (OARSI) grades; grades ranged from 0 (healthy) to 6 (bone remodeling). Maps of longitudinal diffusivity (λ1), transverse diffusivity (λ t), mean diffusivity (MD), and fractional anisotropy (FA) were calculated. Cartilage was segmented, and region of interest (ROI) analysis was performed and compared with histologic findings. Significant differences in MR parameters between the OARSI groups were assessed with the Tukey test. The value of DT imaging in the diagnosis and grading of cartilage damage was assessed with logistic regression analysis. Results: Samples had OARSI grades of 0 (n = 14), 1 (n = 11), 2 (n = 12), 3 (n = 4), and 4 (n = 2). Samples with an OARSI grade greater than 0 had significantly increased ll, lt, and MD (7%-25% increase) in the superficial cartilage growing deeper into cartilage with increasing OARSI grade. Samples with an OARSI grade greater than 0 showed significantly decreased FA in the deep cartilage (225% to 235% decrease), suggesting that changes in the collagen architecture may occur early in cartilage degradation. DTI showed excellent performance in the detection of cartilage damage (accuracy, 0.95; 41 of 43 samples) and good performance in the grading of cartilage damage (accuracy, 0.74; 32 of 43 samples). Conclusion: DT imaging of articular cartilage can enable physicians to detect and grade early cartilage damage. © RSNA, 2012.


Dirr F.,Institute for Clinical Radiology | Hempel J.M.,Ludwig Maximilians University of Munich | Krause E.,Ludwig Maximilians University of Munich | Muller J.,Ludwig Maximilians University of Munich | And 3 more authors.
Otology and Neurotology | Year: 2013

Objective: To analyze the value of a routine x-ray position check after cochlear implantation and to assess if an increased resistance during electrode insertion is a sufficient predictor of electrode misplacement. Study Design: Retrospective data collection. Setting: University hospital. Methods: Plain x-rays (Stenvers' projection) and the respective surgery reports of 218 patients having received cochlear implantation (243 ears) were analyzed for possible electrode misplacements and intraoperative conspicuities during electrode insertion. Results: Electrode misplacement (tip-over, loop, kinking, scalar transition, and incomplete insertion) was observed in 8% of the entire study cohort, but only in 5% if cases with inner ear dysplasia or labyrinthine ossification (n = 28) were excluded from analysis. Intraoperatively, an increased resistance during electrode insertion was found in 16% but only in 8% when cases with inner ear dysplasia or labyrinthine ossification were excluded. The intraoperative finding of an increased resistance during electrode insertion had a sensitivity of 55% and a specificity of 88% for predicting radiographically confirmed electrode misplacements (positive predictive value, 29%; negative predicting value, 96%). Conclusion: Nearly half of the cases of electrode misplacement would have been overlooked if radiographic position checks would have been done only in patients with intraoperative conspicuities during electrode insertion. This finding advocates routine radiographic position checks, although electrode misplacements are relatively rare in patients with regular inner ear anatomy. © 2013, Otology & Neurotology, Inc.


PubMed | Ludwig Maximilians University of Munich and Institute for Clinical Radiology
Type: | Journal: Acta radiologica (Stockholm, Sweden : 1987) | Year: 2016

In unclear pancreatic lesions, a tissue sample can confirm or exclude the suspected diagnosis and help to provide an optimal treatment strategy to each patient. To date only one small study reported on the outcome of computed tomography (CT) fluoroscopy-guided biopsies of the pancreas.To evaluate technical success and diagnostic rate of all CT fluoroscopy-guided core biopsies of the pancreas performed in a single university center during a 10-year period.In this retrospective study we included all patients who underwent a CT fluoroscopy-guided biopsy of a pancreatic mass at our comprehensive cancer center between 2005 and 2014. All interventions were performed under local anesthesia on a 16-row or 128-row CT scanner. Technical success and diagnostic rates as well as complications and effective patient radiation dose were analyzed.One hundred and one patients (54 women; mean age, 63.912.6 years) underwent a total of 104 CT fluoroscopy-guided biopsies of the pancreas. Ninety-eight of 104 interventions (94.2%) could be performed with technical success and at least one tissue sample could be obtained. In 88 of these 98 samples, a definitive pathological diagnosis, consistent with clinical success could be achieved (89.8%). Overall 19 minor and three major complications occurred during the intra- or 30-day post-interventional period and all other interventions could be performed without complications; there was no death attributable to the intervention.CT fluoroscopy-guided biopsy of pancreatic lesions is an effective procedure characterized by a low major complication and a high diagnostic rate.


Strobl F.F.,Institute for Clinical Radiology | Haeussler S.M.,Institute for Clinical Radiology | Paprottka P.M.,Institute for Clinical Radiology | Hoffmann R.-T.,Institute for Clinical Radiology | And 3 more authors.
Skeletal Radiology | Year: 2014

Purpose: To evaluate technical success, complications, and effective dose in patients undergoing CT fluoroscopy-guided iliosacral screw placement for the fixation of unstable posterior pelvic ring injuries. Materials and methods: Our retrospective analysis includes all consecutive patients with vertical sacral fractures and/or injury of the iliosacral joint treated with CT fluoroscopy-guided screw placement in our department from 11/2005 to 03/2013. Interventions were carried out under general anesthesia and CT fluoroscopy (10-20 mAs; 120 kV; 16- or 128-row scanner, Siemens Healthcare, Erlangen, Germany). Technical outcome, major and minor complications, and effective patient dose were analyzed. Results: We treated 99 consecutive patients (mean age 53.1∈±∈21.7 years, 50 male, 49 female) with posterior pelvic ring instability with CT fluoroscopy-guided screw placement. Intervention was technically successful in all patients (n∈=∈99). No major and one minor local complication occurred (1 %, secondary screw dislocation). General complications included three cases of death (3 %) due to pulmonary embolism (n∈=∈1), hemorrhagic shock (n∈=∈1), or cardiac event (n∈=∈1) during a follow-up period of 30 days. General complications were not related to the intervention. Mean effective patient radiation dose per intervention was 12.28 mSv∈±∈7.25 mSv. Mean procedural time was 72.1∈±∈37.4 min. Conclusions: CT fluoroscopy-guided screw placement for the treatment of posterior pelvic ring instabilities can be performed with high technical success and a low complication rate. This method provides excellent intrainterventional visualization of iliac and sacral bones, as well as the sacral neuroforamina for precise screw placement by applying an acceptable effective patient dose. © 2014 ISS.

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