Marc-André Weber

Universität Heidelberg, Heidelburg, Baden-Württemberg, Germany

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Publications (104)275.72 Total impact

  • ISMRM 2015, Toronto, Canada; 06/2015
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    ABSTRACT: Purpose To detail the rationale, design, and future perspective of implementing whole-body magnetic resonance (MR) imaging in the German National Cohort, a large multicentric population-based study. Materials and Methods All institutional review boards approved the study, and informed consent is obtained before study enrollment. Participants are enrolled from a random sample of the general population at five dedicated imaging sites among 18 recruitment centers. MR imaging facilities are equipped with identical 3.0-T imager technology and use uniform MR protocols. Imager-specific hardware and software settings remained constant over the study period. On-site and centralized measures of image quality enable monitoring of completeness of the acquisitions and quality of each of the MR sequences. Certified radiologists read all MR imaging studies for presence of incidental findings according to predefined algorithms. Results Over a 4-year period, six participants per day are examined at each center, totaling a final imaging cohort of approximately 30 000 participants. The MR imaging protocol is identical for each site and comprises a set of 12 native series to cover neurologic, cardiovascular, thoracoabdominal, and musculoskeletal imaging phenotypes totaling approximately 1 hour of imaging time. A dedicated analysis platform as part of a central imaging core incorporates a thin client-based integrative and modular data handling platform to enable multicentric off-site image reading for incidental findings. Scientific analysis will be pursued on a per-project hypothesis-driven basis. Conclusion Population-based whole-body MR imaging as part of the German National Cohort will serve to compile a comprehensive image repository, will provide insight into physiologic variants and subclinical disease burden, and has the potential to enable identification of novel imaging biomarkers of risk. (©) RSNA, 2015 Online supplemental material is available for this article.
    Radiology 05/2015; 277(1):142242. DOI:10.1148/radiol.2015142272 · 6.87 Impact Factor
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    ABSTRACT: To assess the clinical success and costs of computed tomography (CT)-guided radiofrequency ablation (RFA) of osteoblastoma (OB) and spinal osteoid osteoma (OO). Nineteen patients with OB and eight patients with spinal OO were treated with CT-guided RFA. The OBs were localized in the extremities (n = 10), the vertebral column (n = 2), and (juxta-)articular (n = 7). Dedicated procedural techniques included three-dimensional CT-guided access planning in all cases, overlapping RFA needle positions (median, two positions; range, 1-6 RF-electrode positions) within the OB nidus (multiple ablation technique, n = 15), and thermal protection in case of adjacent neural structure in four spinal OO. The data of eight operated OB and ten operated spinal OO patients were used for comparison. Long-term success was assessed by clinical examination and using a questionnaire sent to all operated and RFA-treated patients including visual analogue scales (VAS) regarding the effect of RFA on severity of pain and limitations of daily activities (0-10, with 0 = no pain/limitation up to 10 = maximum or most imaginable pain/limitation). All patients had a clear and persistent pain reduction until the end of follow-up. The mean VAS score for all spinal OO patients and all OB patients treated either with RFA or with surgical excision significantly decreased for severity of pain at night, severity of pain during the day, and both for limitations of daily and of sports activities. RFA is an efficient method for treating OB and spinal OO and should be regarded as the first-line therapy after interdisciplinary individual case discussion.
    Skeletal Radiology 04/2015; 44(7). DOI:10.1007/s00256-015-2139-z · 1.51 Impact Factor
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    ABSTRACT: Diffuse and focal bone marrow infiltration patterns detected by magnetic resonance imaging have been shown to be of prognostic significance in all stages of monoclonal plasma cell disorders and have therefore been incorporated into the definition of the disease. The aim of this retrospective analysis was to develop a rapidly evaluable prognostic scoring system, incorporating the most significant information acquired from magnetic resonance imaging. Therefore, the impact on progression-free and overall survival in 161 transplant-eligible myeloma patients was evaluated. Moderate/severe diffuse infiltration showed a negative prognostic impact on progression-free (p<0.001) and overall survival (p=0.003) compared to salt and pepper/minimal diffuse infiltration. A number of >25 focal lesions on whole-body or >7 on axial magnetic resonance imaging, were associated with an adverse prognosis (progression-free survival: p=0.001/0.003 and overall survival: p=0.04/0.02). A magnetic resonance imaging-based prognostic scoring system, combining grouped diffuse and focal infiltration patterns, was formulated and is applicable to whole-body as well as axial magnetic resonance imaging. The score identified high-risk patients with a median progression-free and overall survival of 23.4 and 55.9 months, respectively (whole-body-based). Multivariate analyses demonstrated that the magnetic resonance imaging-based prognostic score stage III (high-risk) and adverse cytogenetics remain as independent prognostic factors for both, progression-free and overall survival (whole-body-based, progression-free survival: hazard ratio=3.65, p<0.001; overall survival: hazard ratio=5.19, p=0.005). In conclusion, we suggest a magnetic resonance imaging-based prognostic scoring system which is a robust easy to assess and interpret parameter summarizing significant magnetic resonance imaging findings in transplant-eligible multiple myeloma patients. Copyright © 2015, Ferrata Storti Foundation.
    Haematologica 03/2015; 100(6). DOI:10.3324/haematol.2015.124115 · 5.81 Impact Factor

  • IEEE Transactions on Medical Imaging 01/2015; DOI:10.1109/TMI.2015.2502596 · 3.39 Impact Factor
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    ABSTRACT: Digital plain radiographs of the full leg are frequently performed examinations of children and young adults. Thus, the objective of this work was to reduce the radiation exposure dependent on specific indications, and to determine objective quality-control criteria to ensure accurate assessment. Institutional review board approval and informed consent of all participants were obtained. In this prospective, randomized controlled, blinded, two-armed single-center study, 288 evaluable patients underwent plain radiography of the full leg with standard and reduced doses. The evaluation of the plain radiographs was conducted using the following criteria: mechanical axis, leg length, and maturation of the epiphyseal plate. Two blinded radiologists evaluated these criteria using a score ranging from 1 (definitely assessable) to 4 (not assessable). If a single criterion had been evaluated with a score of 3 or more points or all criteria with 2 points, the radiograph was scored as "not assessable". The study was designed as a non-inferiority trial. Eleven (3.8 %) examined X-rays were scored as not assessable. The rate of non-assessable radiographs with 33 % reduced dose was significantly not inferior to the rate of non-assessable radiographs with standard dose. The evaluation of the quality criteria was dose independent. Full-leg plain radiography in patients with knee malalignment can be performed at 33 % reduced dose without loss of relevant diagnostic information.
    Skeletal Radiology 12/2014; 44(3). DOI:10.1007/s00256-014-2004-5 · 1.51 Impact Factor
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    ABSTRACT: Purpose To compare sensitivity of whole-body Computed Tomography (wb-CT) and whole-body Magnetic Resonance Imaging (wb-MRI) with Projection Radiography (PR) regarding each method's ability to detect osteolyses in patients with monoclonal plasma cell disease. Patients and Methods The bone status of 171 patients was evaluated. All patients presented with multiple myeloma (MM) of all stages, monoclonal gammopathy of unknown significance (MGUS) or solitary plasmacytoma. Two groups were formed. Group A consisted of 52 patients (26 females, 26 males) with an average age of 62 years (range, 45-89 years) who received, both, PR and wb-CT as part of their diagnostic work-up. Group B comprised 119 patients (58 females, 61 males) averaging 57 years of age (range 20-80 years) who received, both, PR and wb-MRI. Two experienced radiologists were blinded regarding the disease status and assessed the number and location of osteolyses in consensus. A distinction was made between axial and extra-axial lesions. Results In group A, wb-CT revealed osteolyses in 12 patients (23%) that were not detected in PR. CT was superior in detecting lesions in patients with osteopenia and osteoporosis. Compared with PR, wb-CT was significantly more sensitive in detecting osteolyses than PR (p < 0.001). This was particularly true for axial lesions. Additionally, CT revealed clinically relevant incidental findings in 33 patients (63%). In group B, wb-MRI revealed lesions in 19 patients (16%) that were not detected in PR. All lesions detected by PR were also detected by wb-MRI and wb-CT. Wb-MRI and wb-CT are each superior to PR in detecting axial lesions. Conclusion Wb-CT can detect 23% more focal lesions than PR, especially in the axial skeleton. Therefore, this imaging method should be preferred over PR in the diagnostic work-up and staging of patients with monoclonal plasma cell disease.
    European journal of radiology 07/2014; 83(7). DOI:10.1016/j.ejrad.2014.02.008 · 2.37 Impact Factor
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    ABSTRACT: Purpose: To determine the accuracy and reliability of three-dimensional (3D) T1- and proton density (PD)-weighted turbo spin-echo (TSE) sampling perfection with application-optimized contrasts using different flip-angle evolution (SPACE) compared with conventional 2D sequences in assessment of the shoulder-joint. Materials and methods: Ninety-three subjects were examined on a 3-T MRI system with both conventional 2D-TSE sequences in T1-, T2- and PD-weighting and 3D SPACE sequences in T1- and PD-weighting. All examinations were assessed independently by two reviewers for common pathologies of the shoulder-joint. Agreement between 2D- and 3D-sequences and inter-observer-agreement was evaluated using kappa-statistics. Results: Using conventional 2D TSE sequences as standard of reference, sensitivity, specificity, and accuracy values of 3D SPACE were 81.8%, 95.1%, and 93.5% for injuries of the supraspinatus-tendon (SSP), 81.3%, 93.5%, and 91.4% for the cartilage layer and 82.4%, 98.5%, and 97.5% for the long biceps tendon. Concordance between 2D and 3D was almost perfect for tendinopathies of the SSP (κ=0.85), osteoarthritis (κ=1), luxation of the biceps tendon (κ=1) and adjacent bone marrow (κ=0.92). Inter-observer-agreement was generally higher for conventional 2D TSE sequences (κ, 0.23-1.0), when compared to 3D SPACE sequences (κ, -0.33 to 1.0) except for disorders of the long biceps tendon and supraspinatus tendon rupture. Conclusion: Because of substantial and almost perfect concordance with conventional 2D TSE sequences for common shoulder pathologies, MRI examination-time can be reduced by nearly 40% (up to 11 min) using 3D-SPACE without loss of information.
    European Journal of Radiology 06/2014; 83(10). DOI:10.1016/j.ejrad.2014.06.011 · 2.37 Impact Factor
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    ABSTRACT: The ability to ascertain information pertaining to peripheral perfusion through the analysis of tissues' temporal reaction to the inflow of contrast agent (CA) was first recognized in the early 1990's. Similar to other functional magnetic resonance imaging (MRI) techniques such as arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) MRI, dynamic contrast-enhanced MRI (DCE-MRI) was at first restricted to studies of the brain. Over the last two decades the spectrum of ailments, which have been studied with DCE-MRI, has been extensively broadened and has come to include pathologies of the heart notably infarction, stroke and further cerebral afflictions, a wide range of neoplasms with an emphasis on antiangiogenic treatment and early detection, as well as investigations of the peripheral vascular and musculoskeletal systems. DCE-MRI possesses an unparalleled capacity to quantitatively measure not only perfusion but also other diverse microvascular parameters such as vessel permeability and fluid volume fractions. More over the method is capable of not only assessing blood flowing through an organ, but in contrast to other noninvasive methods, the actual tissue perfusion. These unique features have recently found growing application in the study of the peripheral vascular system and most notably in the diagnosis and treatment of peripheral arterial occlusive disease (PAOD). The first part of this review will elucidate the fundamentals of data acquisition and interpretation of DCE-MRI, two areas that often remain baffling to the clinical and investigating physician because of their complexity. The second part will discuss developments and exciting perspectives of DCE-MRI regarding the assessment of perfusion in the extremities. Emerging clinical applications of DCE-MRI will be reviewed with a special focus on investigation of physiology and pathophysiology of the microvascular and vascular systems of the extremities.
    04/2014; 4(2):147-164. DOI:10.3978/j.issn.2223-3652.2014.03.01
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    ABSTRACT: Purpose: To implement chlorine 35 ((35)Cl) magnetic resonance (MR) at a 7-T whole-body MR system and evaluate its feasibility for imaging humans. Materials and methods: All examinations were performed with ethical review board approval; written informed consent was obtained from all volunteers. Seven examinations each of brain and muscle in healthy volunteers and four examinations of patients were performed. Two patients with histologically confirmed glioblastoma multiforme underwent brain imaging. (35)Cl MR and (35)Cl inversion-recovery (IR) MR were performed. Two patients with genetically confirmed hypokalemic periodic paralysis underwent calf muscle imaging. Seven multiecho sequences (acquisition time, 5 minutes; voxel dimension, 11 mm(3)) were applied to determine transverse relaxation time as affected by magnetic field heterogeneity (T2*) and chlorine concentration. (35)Cl and sodium 23 ((23)Na) MR were conducted with a 7-T whole-body MR system. (35)Cl longitudinal relaxation time (T1) and T2* of healthy human brain and muscle were determined with a three-dimensional density-adapted-projection reconstruction technique to achieve short echo times and high signal-to-noise ratio (SNR) efficiency. A nonlinear least squares routine and mono- (T1) and biexponential (T2*) models were used for curve fitting. Results: Phantom imaging revealed 15-fold lower SNR and much shorter relaxation times for (35)Cl than (23)Na. In vivo T2* was biexponential and extremely short. Monoexponential fits of T1 revealed 9.2 and 4.0 milliseconds ± 0.7 (standard deviation) for brain and muscle, respectively. In glioblastoma tissue, increased Cl(-) concentrations and increased Cl(-) IR signal intensities were detected. Voxel dimension and acquisition time, respectively, were 6 mm(3) and 9 minutes 45 seconds ((35)Cl MR) and 10 mm(3) and 10 minutes ((35)Cl IR MR). In patients with hypokalemic periodic paralysis versus healthy volunteers, Cl(-) and Na(+) concentrations were increased. Cl(-) concentration of muscle could be determined (voxel size, 11 mm(3); total acquisition time, 35 minutes). Conclusion: MR at 7 T enables in vivo imaging of (35)Cl in human brain and muscle in clinically feasible acquisition times (10-35 minutes) and voxel volumes (0.2-1.3 cm(3)). Pathophysiological changes of Cl(-) homeostasis due to cancer or muscular ion channel disease can be visualized.
    Radiology 02/2014; 271(2):131725. DOI:10.1148/radiol.13131725 · 6.87 Impact Factor
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    ABSTRACT: PURPOSE To quantitatively and qualitatively compare both image quality and diagnostic performance of 2D and 3D sequences for dedicated wrist imaging. METHOD AND MATERIALS 16 healthy volunteers (mean age, 26.4 years) and 18 patients (mean age, 36.2 years) with wrist pain were examined using an 8-channel wrist-coil at 3 Tesla MRI. The imaging protocol consisted of 2D-proton-density fat-saturated (PDfs), isotropic 3D MEDIC, 3D-TrueFISP and 3D-PDfs-SPACE sequences. Signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) of cartilage/bone/muscle/fluid and mean overall SNR/CNR were calculated using region-of-interest analysis. Qualitative analysis included overall image quality (OIQ), visibility of important structures and degree of artifacts rated on a five-point scale (0-4). ANOVA and adjusted Wilcoxon-signed-rank tests were applied. The study was approved by the institutional review board and all patients gave informed consent prior to inclusion. RESULTS Mean overall SNR/CNR for 2dPDfs; 3D-PDfs-SPACE; 3D-TrueFISP; 3D-MEDIC was 96/73; 43/28; 61/53; 77/45. SNR and CNR were higher (p<0.01) for 2D-PDfs and 3D-MEDIC for all single items except fluid and fluid/cartilage contrast, where 2D-PDfs and 3D-TrueFISP were superior. 3D-PDfs-SPACE was inferior (p<0.05) in all comparisons. In volunteers OIQ was not different between 3D-TrueFISP (3.5), 3D-MEDIC (3.4) and 2D-PDfs (3.3), but all were superior to 3D-SPACE (2.2, p<0.01). The best sequence for cartilage was the 3D-TrueFISP (3.6), for ligaments/TFCC the 2D-PDfs (3.2/3.4) and the 3D-MEDIC (3.1/3.2). In 18/20 items image quality measures were worse in the patient group (mean, 0.3) with 3D-TrueFISP having the strongest decrease (mean, 0.5), and 2D-PDfs the lowest (mean, 0.1). Overall artifacts were most pronounced in 3D-TrueFISP (mean, 2.3) compared to 2D-PDfs (3.3), 3D PDfs-SPACE (3.4), and 3D-MEDIC (3.3). CONCLUSION Standard 2D-PDfs sequence provides high SNR/CNR, image quality and robustness when compared to 3D sequences. Isotropic 3D-TrueFISP (cartilage) and 3D-MEDIC (ligaments/TFCC) exhibit additional advantages, while 3D-PDfs-SPACE is currently not advantageous. CLINICAL RELEVANCE/APPLICATION When imaging the wrist at 3 Tesla, the sequence protocol should include 2D-PDfs. An additional 3D-TrueFISP sequence can be recommended for assessing cartilage and a 3D-MEDIC for ligaments and TFCC.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: We studied a two-generation family presenting with conditions that included progressive permanent weakness, myopathic myopathy, exercise-induced contracture before normokalaemic periodic paralysis or, if localized to the tibial anterior muscle group, transient compartment-like syndrome (painful acute oedema with neuronal compression and drop foot). (23)Na and (1)H magnetic resonance imaging displayed myoplasmic sodium overload, and oedema. We identified a novel familial Cav1.1 calcium channel mutation, R1242G, localized to the third positive charge of the domain IV voltage sensor. Functional expression of R1242G in the muscular dysgenesis mouse cell line GLT revealed a 28% reduced central pore inward current and a -20 mV shift of the steady-state inactivation curve. Both changes may be at least partially explained by an outward omega (gating pore) current at positive potentials. Moreover, this outward omega current of 27.5 nS/nF may cause the reduction of the overshoot by 13 mV and slowing of the upstroke of action potentials by 36% that are associated with muscle hypoexcitability (permanent weakness and myopathic myopathy). In addition to the outward omega current, we identified an inward omega pore current of 95 nS/nF at negative membrane potentials after long depolarizing pulses that shifts the R1242G residue above the omega pore constriction. A simulation reveals that the inward current might depolarize the fibre sufficiently to trigger calcium release in the absence of an action potential and therefore cause an electrically silent depolarization-induced muscle contracture. Additionally, evidence of the inward current can be found in (23)Na magnetic resonance imaging-detected sodium accumulation and (1)H magnetic resonance imaging-detected oedema. We hypothesize that the episodes are normokalaemic because of depolarization-induced compensatory outward potassium flux through both delayed rectifiers and omega pore. We conclude that the position of the R1242G residue before elicitation of the omega current is decisive for its conductance: if the residue is located below the gating pore as in the resting state then outward currents are observed; if the residue is above the gating pore because of depolarization, as in the inactivated state, then inward currents are observed. This study shows for the first time that functional characterization of omega pore currents is possible using a cultured cell line expressing mutant Cav1.1 channels. Likewise, it is the first calcium channel mutation for complicated normokalaemic periodic paralysis.
    Brain 11/2013; DOI:10.1093/brain/awt300 · 9.20 Impact Factor
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    ABSTRACT: To prospectively evaluate whether dynamic contrast-enhanced (DCE) MRI can assess vascularity within non-unions and predicts clinical outcome in combination with the clinical Non-Union Scoring System (NUSS). Fifty-eight patients with non-unions of extremities on CT underwent 3-T DCE MRI. Signal intensity curves obtained from a region-of-interest analysis were subdivided into those with more intense contrast agent uptake within the non-union than in adjacent muscle (vascularised non-union) and those with similar or less contrast uptake. The pharmacokinetic parameters of the Tofts model K trans, K ep, iAUC and V e were correlated with union at CT 1 year later (n = 49). Despite inserted osteosynthetic material, DCE parameters could be evaluated in 57 fractures. The sensitivity/specificity of vascularised non-unions as an indicator of good outcome was 83.9 %/50.0 % compared to 96.8 %/33.3 % using NUSS (n = 49). Logistic regression revealed a significant impact of NUSS on outcome (P = 0.04, odds ratio = 0.93). At first examination, median iAUC (initial area under the enhancement curve) for the ratio non-union/muscle was 10.28 in patients with good outcome compared with 3.77 in non-responders (P = 0.023). K trans, K ep and Ve within the non-union were not significantly different initially (n = 57) or 1 year later (n = 19). DCE MRI can assess vascularity in fracture non-unions. A vascularised non-union correlates with good outcome. • Dynamic contrast-enhanced magnetic resonance imaging can assess vascularity within bony non-unions. • Vascularised ununited fractures appear better at 1-year CT than poorly vascularised fractures. • Non-union healing after osteosynthesis or osteoinductive drugs fundamentally requires vascularity. • DCE MRI predicts treatment outcome better than the clinical Non-Union Scoring System. • DCE MRI is clinically feasible to predict treatment outcome in bony non-unions.
    European Radiology 10/2013; 24(2). DOI:10.1007/s00330-013-3043-3 · 4.01 Impact Factor
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    ABSTRACT: Purpose: To investigate muscular micro-perfusion by employing dynamic contrast-enhanced ultrasound (CEUS) and performing transient arterial occlusion in patients with type 2 diabetes mellitus (DM-2). Methods: Twenty DM-2 patients (mean age, 58 ± 8.6 years; duration of diabetes, 15.4 ± 12.1 years) and 20 healthy volunteers (mean age, 54 ± 5.4 years) participated. CEUS was applied to the calf, while 4.8 mL of SonoVue(®) was injected intravenously. At the thigh level, arterial occlusion (60 s) was performed. CEUS parameters (tmax, max, AUCpost and m) were evaluated and Pearson-product-moment correlation coefficients were computed. Results: A moderate negative correlation of HbA1c and max was established (-0.53). Max in patients with DM-2 >10 years was 79.89 ± 37.4. Max in patients with DM-2 duration <10 years was 137.62 ± 71.72 (p = 0.04). AUCpost in patients with DM-2 duration >10 years was 3924.01 ± 1630.52. AUCpost in patients with DM-2 duration <10 years was 6453.59 ± 3206.23 (p = 0.04). Conclusion: Patients with long history of DM-2 present with impaired muscular perfusion. CEUS and transient arterial occlusion may provide appropriate methods for semi-quantitative evaluation of muscular micro-perfusion in patients with DM-2.
    Diabetes & Vascular Disease Research 05/2013; 10(5). DOI:10.1177/1479164113484165 · 2.83 Impact Factor
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    ABSTRACT: Purpose: We aimed to retrospectively evaluate the computed tomography (CT) and magnetic resonance imaging (MRI) findings of patients with osteoid osteoma treated with CT-guided radiofrequency ablation (RFA) along with the clinical outcome and long-term success. Materials and methods: Seventy-three CT-guided RFA procedures were performed in 72 patients. The long-term success was assessed using a questionnaire including several visual analog scale scores. The CT evaluation included pre- and immediate postprocedural imaging of all 72 patients, and MRI was performed in 18 patients with follow-up imaging (mean, 3.4±2.2 months). The evaluation criteria included nidus morphology and a correlation with markers of clinical success. Results: The primary technique effectiveness rate was 71/72 (99%). One relapse was successfully retreated, leading to a secondary technique effectiveness rate of 72/72 (100%). The long-term follow-up (mean, 51.2±31.2 months; range, 3-109 months) revealed a highly significant reduction of all assessed limitation scores (P < 0.001). The CT morphology was typical in all cases and did not change during the short-term follow-up. The follow-up MRI patterns varied considerably, including persistent nidus contrast enhancement in one-third (6/18) and persistent marrow edema in half (9/18) of the patients. None of the investigated MRI and CT patterns correlated with the clinical outcome. Conclusion: The long-term outcome of CT-guided RFA of osteoid osteoma is excellent. There is no correlation of the CT and MRI patterns with the clinical outcome. Thus, the treatment decisions should not be solely based on the imaging findings. Investigators should also be aware of the variety of imaging patterns after RFA.
    Diagnostic and interventional radiology (Ankara, Turkey) 03/2013; 19(4). DOI:10.5152/dir.2013.096 · 1.43 Impact Factor
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    ABSTRACT: To prospectively assess whether changes in apparent diffusion coefficient (ADC) values or standardized uptake value (SUV) changes in 18F-fluorodeoxyglucose (FDG) PET correlate with treatment response under neoadjuvant chemotherapy in patients with locally advanced adenocarcinoma of the esophagogastric junction (AEG). Fifteen patients (median age, 64 years) with histologically proven AEG type I and II received 1.5 Tesla MRI including "diffusion-weighted imaging" and FDG PET/CT before and 14 days after neoadjuvant EOX chemotherapy. The FDG uptake of the tumor was quantified by calculating the SUV in static PET scans. ADC values within the tumor tissue were quantitatively assessed using a region-of-interest analysis excluding necrotic areas. Early metabolic response was defined as a decrease in the SUVmean > /= 35% in FDG PET two weeks following the start of neoadjuvant chemotherapy, which had been reported to be predictive of histopathological response and survival. Concordance between ADC and SUV changes, differences at first examination and overall survival were assessed. The ADC within the AEG tumors was significantly lower than in normal esophagus and increased following neoadjuvant chemotherapy by 16.0 +/- 1.1% (p=0.007). Tumor glucose SUV decreased by 29.1 +/- 23.2% (p=0.002). Initial ADC and SUV were comparable in both groups (p=0.65, p=0.82). ADC increase and metabolic PET-response were concordant in 73.3% of all patients. The median overall survival was 757 days for PET-responders and 623 days for PET-non-responders (p=0.138). The ADC increase in AEG tumors following chemotherapy is concordant in the majority of cases to PET-response, but not correlated to prognosis in this study.
    Journal of gastrointestinal and liver diseases: JGLD 03/2013; 22(1):45-52. · 2.20 Impact Factor
  • Armin M. Nagel · Marc-André Weber · Arijitt Borthakur · Ravinder Reddy ·
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    ABSTRACT: Proton MRI is the mainstay of muscle MR imaging, however with the advent of dedicated coil and sequence technology, also non-proton MRI is now possible using high-field MRI units. This chapter includes a discussion of the principles and challenges of non-proton muscle imaging with focus on the use of sodium MRI. Dedicated sequences and the benefit of higher field strength will be discussed and clinical applications within the musculoskeletal system, such as sodium MRI in muscular diseases and cartilage/joint abnormalities will be reviewed. Moreover, other nuclei that are prone to MR imaging, such as chlorine, potassium, and oxygen will also be addressed.
    01/2013: pages 115-133;

Publication Stats

2k Citations
275.72 Total Impact Points


  • 2003-2015
    • Universität Heidelberg
      • • Department of Diagnostic and Interventional Radiology
      • • Department of Neurology
      Heidelburg, Baden-Württemberg, Germany
  • 2014
    • Case Western Reserve University
      Cleveland, Ohio, United States
  • 2003-2014
    • German Cancer Research Center
      • Division of Radiology
      Heidelburg, Baden-Württemberg, Germany
  • 2013
    • evaplan at the University Hospital Heidelberg
      Heidelburg, Baden-Württemberg, Germany
  • 2007
    • National Center for Tumor Diseases (NCT) Heidelberg
      Heidelburg, Baden-Württemberg, Germany