U Ernemann

University of Tuebingen, Tübingen, Baden-Württemberg, Germany

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Publications (126)228.28 Total impact

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    ABSTRACT: A new method for diffusion-weighted imaging (DWI) using independent parallel transmission technique resulting in zoomed DWI was applied in four patients suffering from acute spinal cord ischemia.
    Clinical Neuroradiology 08/2014; · 1.62 Impact Factor
  • U Ernemann
    Clinical Neuroradiology 05/2014; · 1.62 Impact Factor
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    ABSTRACT: The evaluation of carotid-cavernous fistulas (CCFs) and the intracranial vasculature has been predominantly carried out using conventional digital subtraction angiography (DSA). Recent developments in time-resolved magnetic resonance angiography (MRA) provide the opportunity to assess both multiple arterial and venous phases with high temporal and spatial resolution. Here, we investigated the feasibility of this technique to functionally assess CCF prior to intervention. Six consecutive patients with clinical symptoms of a CCF were scheduled for clinically indicated MRA and underwent a protocol that comprised conventional imaging sequences and high resolution time-resolved MRA with interleaved stochastic trajectories (TWIST). The location of the fistulous communication, the flow pattern, and venous drainage were determined by time-resolved MRA and compared with DSA which was available in five out of six patients. Typical morphological findings (including enlargement of the superior ophthalmic vein, exophthalmos) were found in all cases in both conventional MRI and time-resolved MRA source data. The temporal resolution of time-resolved MRA enabled a good separation of the early filling of the cavernous sinus during the arterial phase. Direct fistulous communication was assessed in three patients with good correlation to DSA, whereas indirect CCF could not definitely be visualized. The time-resolved MRA provided information about the flow pattern and the venous drainage of the fistula in all patients, which is essential for therapy planning. Time-resolved MRA provides important morphological and functional information in patients with CCF. Although DSA remains the gold standard for diagnosis and exact classification of fistulas, time-resolved MRA can provide the relevant hemodynamic information to plan interventional treatment as a one-step procedure with a focused diagnostic workup.
    Clinical neuroradiology. 03/2014;
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    ABSTRACT: We investigated the agreement of dual-energy computed tomography angiography (DE-CTA) and contrast-enhanced magnetic resonance angiography (CE-MRA)in the quantitative measurement of stenoses of the internal carotid artery in comparison with digital subtraction angiography (DSA). A total of 21 patients with stenoses of the external carotid artery were investigated with a DE-CTA and CE-MRAbefore undergoing carotid angioplasty. The grade of the stenoses was assessed in axial multiplanar reformations (MPR) before and multi-intensity projections (MIP) after plaque subtraction (PS) and compared with results from CE-MRA and DSA according to the North American Symptomatic Carotid Endarterectomy Trial. Average grades of stenoses were 80.7 ± 16.1 % (DSA), 81.4 ± 15.3 % (MRA), 80.0 ± 16.7 % (DE-CTA-MPR), and 85.2 ± 14.7 % (DE-CTA-PS-MIP). Of 21 stenoses, 6 were filiform (stenosis grade, 99 %) in the DSA examination. Five of these cases were identified as pseudo-occlusions in MRA, while four were considered as occlusions in DE-CTA-PS-MIP. Another four cases were identified as pseudo-occlusion in DE-CTA-PS-MIP, which were identified as 90 % stenosis in the DSA examination. In comparison with the gold standard DSA, DE-CTA-MPR had a slightly better agreement in measuring the degree of stenosis of the internal carotid arteries than CE-MRA. In DE-CTA-PS-MIP images, a systematic overestimation has to be taken into account due to partial extinction of the lumen by the PS algorithm. Nevertheless, DE-CTA should be preferred in imaging patients with carotid artery stenosis in the presence of extensive calcifications.
    Clinical neuroradiology. 12/2013;
  • RöFo - Fortschritte auf dem Gebiet der R 11/2013; 185(11):1021-5. · 2.76 Impact Factor
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    ABSTRACT: PURPOSE: Iterative reconstruction has recently been revisited as a promising concept for substantial CT dose reduction. The purpose of this study was to assess the potential benefit of sinogram affirmed iterative reconstruction (SAFIRE) in head CT by comparing objective and subjective image quality at reduced tube current with standard dose filtered back projection (FBP). MATERIALS AND METHODS: Non-contrast reduced dose head CT (255mAs, CTDIvol 47.8mGy) was performed in thirty consecutive patients and reconstructed with SAFIRE and FBP. Images were assessed in terms of quantitative and qualitative image quality and compared with FBP of standard dose acquisitions (320mAs, CTDIvol 59.7mGy). RESULTS: In reduced dose CT examinations, use of SAFIRE versus FBP resulted in 47% increase in contrast-to-noise ratio (CNR) (2.49 vs. 1.69; p<0.0001). While reduction of tube current was associated with 13% decrease in CNR, quantitative degradation of image quality at lower dose was more than compensated through SAFIRE (2.49 vs. 1.96; p=0.0004). Objective measurements of image sharpness were comparable between FBP and SAFIRE reconstructions (575.9±74.1 vs. 583.4±74.7 change in HU/Pixel; p=0.28). Compared to standard dose FBP, subjective grading of noise as well as overall image quality scores were significantly improved when SAFIRE was used in reduced dose exams (1.3 vs. 1.6, p=0.006; 1.3 vs. 1.7, p=0.026). CONCLUSION: At 20% dose reduction, reconstruction of head CT by SAFIRE provides above standard objective and subjective image quality, suggesting potential for more vigorous dose savings in neuroradiology CT applications.
    European journal of radiology 04/2013; · 2.65 Impact Factor
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    ABSTRACT: Aims A safe total resection followed by adjuvant chemoradiotherapy should be the primary goal in the treatment of glioblastomas (GBMs) to enable patients the longest survival possible. 5-aminolevulinic acid (5-ALA)- and intraoperative MRI (iMRI)-assisted surgery, have been shown in prospective randomized trials to significantly improve the extent of resection (EOR) and subsequently survival of patients with GBMs. No direct comparison of surgical results between both techniques has been published to date. We analyzed the additional value of iMRI in glioblastoma surgery compared to conventional surgery with and without 5-ALA. Methods Residual tumor volumes, clinical parameters and 6-month progression-free survival (6M-PFS) rates after GBM resection were analyzed retrospectively for 117 patients after conventional, 5-ALA and iMRI-assisted surgery. Results Mean residual tumor volume (range) after iMRI-assisted surgery [0.5 (0.0–4.7) cm3] was significantly smaller compared to the residual tumor volume after 5-ALA-guided surgery [1.9 (0.0–13.2) cm3; p = .022], which again was significantly smaller than in conventional white-light surgery [4.7 (0.0–30.6) cm3; p = .007]. Total resections were significantly more common in iMRI- (74%) than in 5-ALA-assisted (46%, p = .05) or white-light surgery (13%, p = .03). Improvement of the EOR by using iMRI was safely achievable as peri- and postoperative morbidities were comparable between cohorts. Total resections increased 6M-PFS from 32% to 45%. Conclusions Analysis of residual tumor volumes, total resections and neurological outcomes demonstrate that iMRI may be significantly superior to 5-ALA and white-light surgery for glioblastomas at comparable peri- and postoperative morbidities. Longer 6M-PFS was observed in patients with total resections.
    European journal of surgical oncology: the journal of the European Society of Surgical Oncology and the British Association of Surgical Oncology 01/2013; · 2.56 Impact Factor
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    ABSTRACT: INTRODUCTION: High-pitch CT angiography (CTA) is a recent innovation that allows significant shortening of scan time with volume coverage of 43 mm per second. The aim of our study was to assess this technique in CTA of the head and neck. METHODS: CTA of supra-aortic arteries was performed in 50 patients using two acquisition protocols: conventional single-source 64-slice (pitch 1.2) and high-pitch dual-source 128-slice CT (pitch 3.2). Subjective and objective image quality of supra-aortic vessel ostia as well as intra- and extra-cranial segments was retrospectively assessed by blinded readers and radiation dose compared between the two protocols. RESULTS: Conventional and high-pitch CTA achieved comparable signal-to-noise ratios in arterial (54.3 ± 16.5 versus 57.3 ± 14.8; p = 0.50) and venous segments (15.8 ± 6.7 versus 18.9 ± 8.9; p = 0.21). High-pitch scanning was, however, associated with sharper delineation of vessel contours and image quality significantly improved at the level of supra-aortic vessel ostia (p < 0.0001) as well as along the brachiocephalic trunk (p < 0.0001), the subclavian arteries (p < 0.0001), proximal common carotid arteries (p = 0.01), and vertebral V1 segments (p < 0.0001). Using the high-pitch mode, the dose-length product was reduced by about 35 % (218.2 ± 30 versus 141.8 ± 20 mGy × cm). CONCLUSIONS: Due to elimination of transmitted cardiac motion, high-pitch CTA of the neck improves image quality in the proximity of the aortic arch while significantly lowering radiation dose. The technique thus qualifies as a promising alternative to conventional spiral CTA and may be particularly useful for identification of ostial stenosis.
    Neuroradiology 12/2012; · 2.37 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 12/2012; 184(12):1079-82. · 2.76 Impact Factor
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    ABSTRACT: Behçet's disease is a systemic disorder with the histopathological correlate of leukocytoclastic vasculitis. Pathogenetically, besides a strong genetic component participation of the innate immune system and an autoinflammatory component are discussed. The disease is most common in countries along the former silk route but in Germany the disease is rare (prevalence approximately 0.6/100,000). Oral aphthous ulcers are the main symptom, followed by skin manifestations, genital ulcers and oligoarthritis of large joints. Severe manifestations, threatening quality of life and even life itself, are the gastrointestinal manifestations which often perforate, arterial, mainly pulmonary arterial aneurysms which cause life-threatening bleeding, CNS manifestations and ocular disease, which with occlusive retinal vasculitis often leads to blindness. For milder manifestations low-dose steroids and colchicine are used, for moderate manifestations such as arthritis or ocular disease not immediately threatening visual acuity, azathioprin or cyclosporin A are combined with steroids. For severe manifestations, interferon-alpha, TNF-antagonists or cytotoxic drugs are recommended. Interleukin 1 (IL-1) antagonists are currently being examined in clinical studies.
    Zeitschrift für Rheumatologie 10/2012; 71(8):685-97. · 0.46 Impact Factor
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    ABSTRACT: Der Morbus Behçet ist eine Systemerkrankung mit dem histologischen Korrelat einer leukozytoklastischen Vaskulitis. Pathogenetisch werden neben einer starken genetischen Komponente eine Beteiligung des angeborenen Immunsystems sowie auch eine autoinflammatorische Komponente diskutiert. Die Erkrankung ist am häufigsten in Ländern entlang der früheren Seidenstraße, in Deutschland ist die Erkrankung dagegen selten. Hauptsymptome sind orale Aphthen und Hautmanifestationen, gefolgt von genitalen Aphthen und einer Oligoarthritis der großen Gelenke. Schwerwiegende Manifestationen sind die gastrointestinale Manifestation mit Perforationsneigung, die arteriellen, vor allem pulmonalarteriellen Aeurysmen, die ZNS-Manifestationen und die Augenbeteiligung. Therapeutisch kommen bei leichten Krankheitsmanifestationen niedrig dosierte Steroide und Colchicin zum Einsatz, bei mittelgradigen Manifestationen Azathioprin und Steroide, alternativ Cyclosporin A und Steroide, bei schweren Manifestationen Interferon-α, TNF-Antagonisten oder Zytostatika. In Studien werden aktuell Interleukin-1-Antagonisten erprobt.
    Zeitschrift für Rheumatologie 10/2012; 71(8). · 0.46 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 08/2012; 184(8):679-83. · 2.76 Impact Factor
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    ABSTRACT: OBJECTIVE: To provide a practical review of the spectrum of possible imaging findings in patients with progressive multifocal leukoencephalopathy (PML) and to address differentials. CONCLUSION: PML manifests with a broad spectrum of imaging features. Besides knowledge of preferential location, extent, temporal course, enhancement, results of functional imaging and clinical setting, recognition of imaging findings reflecting active demyelination may help the clinician in appropriately narrowing down the differential diagnosis.
    Clinical neurology and neurosurgery 07/2012; 114(8):1123-30. · 1.30 Impact Factor
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    ABSTRACT: To quantify and compare T2 signal and apparent diffusion coefficient (ADC) in pilocytic and pilomyxoid astrocytoma (PA and PMA) and correlate results with myxoid content. Echo-planar diffusion weighted images (DWI) and standard magnetic resonance imaging (MRI) findings were reviewed retrospectively in patients with PA (n=34) and PMA (n=8). Regions of interest (ROIs) were drawn on ADC maps within tumor parts with lowest ADC values. Apparent diffusion coefficient values in tumor were normalized to those in cerebrospinal fluid (ADC/CSF). The ratio of T2 signal intensity in solid tumor parts to CSF (T2/CSF) was registered. Myxoid matrix was histologically quantified retrospectively in 8 PMAs and 17 PAs and correlated with imaging findings. Mean ADC/CSF for PA and PMA was 0.53±0.10 and 0.69±0.10 (p<0.01). Mean T2/CSF for PA and PMA was 0.78±0.19 and 0.93±0.09 (p<0.01). Mean proportion of myxoid tumor matrix in PA was 50% (range, 10-100%) and 93% (range, 90-100%) in PMA (p=0.004). Eight patients (32%; all PA) had less than 50% myxoid content and 17 (68%; 8 PA; 9 PMA) had more. There was positive correlation of ADC/CSF, T2/CSF and ADC (r2=0.61, 0.65 and 0.60 respectively) and significant difference between the groups with more and less than 50% myxoid content (p=0.01 for ADC/CSF and T2/CSF and p=0.02 for ADC). General imaging features of PA and PMA are non-specific, ADC values and T2 signal intensity are generally higher in the latter, reflecting the proportion of myxoid matrix in these tumors.
    The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques 07/2012; 39(4):491-8. · 1.60 Impact Factor
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    ABSTRACT: Behcet's disease is a multisystem disorder with the histopathological correlate of leukocytoclastic vasculitis. The classification criteria for the disease include the presence of recurrent oral aphthous ulcers combined with at least two other manifestations, such as genital aphthous ulcers, skin manifestations (mostly erythema nodosa or pseudofolliculitis) and ocular manifestations (panuveitis or posterior uveitis with retinal vasculitis). A positive pathergy test is regarded as pathognomonic for the disease and a sterile papulopustule occurs after a sterile needle prick of the forearm. However, this test is positive in only 15% of the patients. The prognosis of Behcet's disease becomes unfavorable when vital organs are involved. This is the case for involvement of the central nervous system which occurs in 10% of patients, arterial and pulmonary arterial aneurysms and gastrointestinal involvement, which clinically and histopathologically is difficult to differentiate from inflammatory bowel disease but tends to perforate. Oligoarthritis, which occurs in approximately 50% of the patients, causes problems concerning the differential diagnosis from classical forms of spondyloarthritis. Behcet's disease is associated with HLA-B51 in 50-80% of the cases depending on the country of origin of the patient. The prognosis becomes unfavorable if the disease manifests in young male patients. The treatment of extraocular manifestations depends on the aggressiveness. Milder manifestations are treated with low dose prednisolone and steroid sparing immunosuppressants, such as azathioprine or cyclosporine A. In cases with more severe manifestations, such as central nervous system (CNS) involvement cyclophosphamide or TNF antagonists and in selected cases also interferon alpha can be considered.
    Der Ophthalmologe 06/2012; 109(6):548-57. · 0.72 Impact Factor
  • A Korn, C Braun, M Fenchel, U Ernemann, M Horger
    RöFo - Fortschritte auf dem Gebiet der R 05/2012; 184(5):397-401. · 2.76 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 03/2012; 184(3):191-5. · 2.76 Impact Factor
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    ABSTRACT: IR has recently demonstrated its capacity to reduce noise and permit dose reduction in abdominal and thoracic CT applications. The purpose of our study was to assess the potential benefit of IR in head CT by comparing objective and subjective image quality with standard FBP at various dose levels. Ninety consecutive patients were randomly assigned to undergo nonenhanced and contrast-enhanced head CT at a standard dose (320 mAs; CTDI, 60.1) or 15% (275 mAs; CTDI, 51.8) and 30% (225 mAs; CTDI, 42.3) dose reduction. All acquisitions were reconstructed with IR in image space, and FBP and images were assessed in terms of quantitative and qualitative IQ. Compared with FBP, IR resulted in lower image noise (P ≤ .02), higher CNR (P ≤ .03), and improved subjective image quality (P ≤ .002) at all dose levels. While degradation of objective and subjective IQ at 15% dose reduction was fully compensated by IR (CNR, 1.98 ± 0.4 at 320 mAs with FBP versus 2.05 ± 0.4 at 275 mAs with IR; IQ, 1.8 versus 1.7), IQ was considerably poorer at 70% standard dose despite using the iterative approach (CNR, 1.98 ± 0.3 at 320 mAs with FBP versus 1.85 ± 0.4 at 225 mAs with IR, P = .18; IQ, 1.8 versus 2.2, P = .03). Linear regression analysis of CNR against tube current suggests that standard CNR may be obtained until approximately 20.4% dose reduction when IR is used. Compared with conventional FBP, IR of head CT is associated with significant improvement of objective and subjective IQ and may allow dose reductions in the range of 20% without compromising standard image quality.
    American Journal of Neuroradiology 02/2012; 33(2):218-24. · 3.17 Impact Factor
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    ABSTRACT: The present work illustrates the current state of image quality and diagnostic accuracy in a new hybrid BrainPET/MR. 50 patients with intracranial masses, head and upper neck tumors or neurodegenerative diseases were examined with a hybrid BrainPET/MR consisting of a conventional 3T MR system and an MR-compatible PET insert. Directly before PET/MR, all patients underwent a PET/CT examination with either [(18)F]-FDG, [(11)C]-methionine or [(68)Ga]-DOTATOC. In addition to anatomical MR scans, functional sequences were performed including diffusion tensor imaging (DTI), arterial spin labeling (ASL) and proton-spectroscopy. Image quality score of MR imaging was evaluated using a 4-point-scale. PET data quality was assessed by evaluating FDG-uptake and tumor delineation with [(11)C]-methionine and [(68)Ga]-DOTATOC. FDG uptake quantification accuracy was evaluated by means of ROI analysis (right and left frontal and temporo-occipital lobes). The asymmetry indices and ratios between frontal and occipital ROIs were compared. In 45/50 patients, PET/MR examination was successful. Visual analysis revealed a diagnostic image quality of anatomical MR imaging (mean quality score T2 FSE: 1.27±0.54; FLAIR: 1.38±0.61). ASL and proton-spectroscopy was possible in all cases. In DTI, dental artifacts lead to one non-diagnostic dataset (mean quality score DTI: 1.32±0.69; ASL: 1.10±0.31). PET datasets of PET/MR and PET/CT offered comparable tumor delineation with [(11)C]-methionine; additional lesions were found in 2/8 [(68)Ga]-DOTATOC-PET in the PET/MR. Mean asymmetry index revealed a high accordance between PET/MR and PET/CT (1.5±2.2% vs. 0.9±3.6%; mean ratio (frontal/parieto-occipital) 0.93±0.08 vs. 0.96±0.05), respectively. The hybrid BrainPET/MR allows for molecular, anatomical and functional imaging with uncompromised MR image quality and a high accordance of PET results between PET/MR and PET/CT. These results justify the application of this technique in further clinical studies and may contribute to the transfer into whole-body PET/MR systems.
    European journal of radiology 01/2012; 81(11):3472-8. · 2.65 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 01/2012; 184(1):1-5. · 2.76 Impact Factor

Publication Stats

462 Citations
228.28 Total Impact Points


  • 1997–2013
    • University of Tuebingen
      • • Department of Internal Medicine
      • • Department of Neurology
      • • Department of Neurosurgery
      Tübingen, Baden-Württemberg, Germany
  • 2000–2012
    • Universitätsklinikum Tübingen
      • • Interdisziplinäre Klinische Immunologie, Rheumatologie und Autoimmunerkrankungen
      • • Department of Neurosurgery
      • • Hospital and Policlinic for Oral and Maxillofacial Surgery
      • • Division of Neurourology
      Tübingen, Baden-Württemberg, Germany
    • Deutsche Gesellschaft für Mund-, Kiefer- und Gesichtschirurgie e.V.
      Tübingen, Baden-Württemberg, Germany
  • 2007–2008
    • Universitätsmedizin Göttingen
      • Department of Neurology
      Göttingen, Lower Saxony, Germany