Susanne C Ladd

University Hospital Essen, Essen, North Rhine-Westphalia, Germany

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Publications (96)187.74 Total impact

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    ABSTRACT: The aims of this study were to investigate the subjective discomfort and sensory side effects during ultrahigh field (UHF) magnetic resonance imaging (MRI) examinations in a large-scale study and to evaluate differences between magnetic resonance (MR) sites. Four MR sites with a 7-T MR system and 2 MR sites with a 9.4-T MR system participated in this multicenter study with a total number of 3457 completed questionnaires on causes of discomfort and sensations during the examination. For a pooled retrospective analysis of the results from the partially different questionnaires, all data were adapted to an answer option with a 4-point scale (0 = no discomfort/side effect, 3 = very unpleasant/very strong sensation). To differentiate effects evoked by the low-frequency time-varying magnetic fields due to movement through the static magnetic field, most questionnaires separated the manifestation of sensory side effects during movement on the patient table from manifestation while lying still in the isocenter. In general, a high acceptance of UHF examinations was found, where in 82% of the completed questionnaires, the subjects stated the examination to be at least tolerable. Although in 7.6% of the questionnaires, subjects felt discomfort during the examination, only 0.9% of the image acquisitions had to be terminated prematurely. No adverse events occurred in any of the examinations. Only 1% of the subjects were unwilling to undergo further UHF MRI examinations. Examination duration was the most complained cause of discomfort, followed by acoustic noise and lying still. All magnetic-field-related sensations were more pronounced when moving the patient table versus the isocenter position (19%/2% of the subjects felt unpleasant vertigo during the moving/stationary state). In general, vertigo was the most often stated sensory side effect and was more pronounced at 9.4 T compared with 7 T. However, the results varied substantially among the different sites. The high levels of subjective acceptance found in this study lead to the conclusion that UHF MRI would be tolerated as a diagnostic tool in clinical practice. For more consistent data ascertainment, we propose a standardized questionnaire for subjective perception monitoring.
    Investigative radiology 03/2014; · 4.85 Impact Factor
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    ABSTRACT: Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or "postural instability" even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n = 27), 7 T no RF (n = 22), 7 T only B0 (n = 20), 7 T in & out B0 (n = 20), 1.5 T no RF (n = 20), 0 T (n = 15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in & out B0. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B0) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B0 or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in & out B0 exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or "over-compensation" of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role.
    PLoS ONE 01/2014; 9(3):e92104. · 3.53 Impact Factor
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    ABSTRACT: INTRODUCTION: Our purpose was to analyze the long-term evolution of wide neck cerebral aneurysms treated with stent assistance. METHODS: Data of consecutive patients treated with the Neuroform stent over 9 years were retrospectively analyzed with emphasis on periprocedural complications, aneurysm occlusion grade evolution, and in-stent stenosis rates. RESULTS: Altogether, 113 patients with 117 unruptured and ruptured aneurysms were subject of analysis. Mean aneurysm size was 9.4 mm, and mean neck size was 4.7 mm. Procedural thromboembolic and hemorrhagic complications affected eight (6.8 %) and four cases (3.4 %), respectively. Immediate complete occlusion and occlusion with residual neck was achieved in 85 % of cases, which at the first follow-up of 6 months, changed to 77 and 76 % at 36 months. Aneurysms ≥10 mm showed a higher tendency of recurrence. During the overall follow-up time ranging from 1 to 9 years, an in-stent stenosis of ≥50 % was observed only in three cases, all of them being asymptomatic. CONCLUSIONS: Stent-assisted coiling of wide neck aneurysms provided stable occlusion over the long-term follow-up, with very low and silent in-stent stenosis rates. Some incompletely occluded aneurysms showed a tendency of progressive occlusion; however, this was counterbalanced by the regrowth of others.
    Neuroradiology 01/2013; · 2.70 Impact Factor
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    ABSTRACT: Up to about one-quarter of patients treated with neoadjuvant chemotherapy do not adequately respond to the given treatment. By a differentiation between responders and non-responders ineffective toxic therapies can be prevented. To retrospectively test if FDG-PET/CT is able to early differentiate between breast cancer lesions with pathological complete response (pCR) and lesions without pathological complete response (npCR) after two cycles of neoadjuvant chemotherapy (NACT). In this retrospective study 26 breast cancer patients (mean age, 46.9 years ± 9.9 years) underwent a pre-therapeutic FDG-PET/CT scan and a subsequent FDG-PET/CT after the second cycle of NACT. Histopathology of resected specimen served as the reference standard. Maximum standardized uptake values (SUVmax) of cancer lesions before and after the second cycle of NACT were measured. Two evaluation algorithms were used: (a) pCR: Sinn Score 3 and 4, npCR: Sinn Score 0-2; (b) pCR: Sinn Score 4, npCR: Sinn Score 0-3. The absolute and relative decline of the SUVmax (ΔSUVmax, ΔSUVmax(%))was calculated. Differences of the SUVmax as well as of the SUVmax decline between pCR lesions and npCR lesions were tested for statistical significance P < 0.05. To identify the optimal cut-off value of ΔSUVmax(%) to differentiate between pCR lesions and npCR lesions a receiver-operating curve (ROC) analysis was performed. Using evaluation algorithm A the ΔSUVmax was 13.5 (pCR group) and 3.9 (npCR group) (P = 0.006); the ΔSUVmax(%) was 79% and 47%, respectively (P = 0.001). On ROC analysis an optimal cut-off ΔSUVmax(%) of 66% was found. Using evaluation algorithm B the ΔSUVmax was 17.5 (pCR group) and 4.9 (npCR group) (P = 0.013); the ΔSUVmax(%) was 89% and 51%, respectively (P = 0.003). On ROC analysis an optimal cut-off ΔSUVmax(%) of 88% was found. FDG-PET/CT may be able to early differentiate between pCR and npCR of primary breast cancer lesions after two cycles of NACT.
    Acta Radiologica 07/2012; 53(6):628-36. · 1.33 Impact Factor
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    ABSTRACT: OBJECTIVE: To present imaging characteristics of the ankle at 7.0 T and to investigate the appearance and image quality of presumed pathologies of ankles without physical strain as well as of ankles after a marathon run in comparison to 1.5 T. MATERIALS AND METHODS: Appearance of presumed pathologic findings and image quality of TSE (PD, T2, and STIR) and GRE sequences (MEDIC, DESS, and/or CISS) at 7.0 T and 1.5 T MRI were compared by two senior radiologists in consensus in two healthy controls without strain and in six marathon runners after a full-length marathon (eight males, mean age 49.1 years). RESULTS: Overall, 7.0 T MRI allowed for higher resolution images for most of the sequences while requiring comparable acquisition times and achieving high contrast images mainly in gradient echo sequences. Bursal or presumed peritendineal fluid and/or edematous tissue, which were found in seven of eight subjects, could be best appreciated with 7.0 T MEDIC. Other findings with sharper delineation at 7.0 T included cartilage defects (best: CISS), osseous avulsions, and osteophytes (best: DESS). Nevertheless, 1.5 T STIR imaging enabled assessment of a tibiotalar bone edema-like lesion in two runners, which was barely visible at 7.0 T using STIR, but not with any other sequence at 7.0 T including MEDIC (with frequency selective fat suppression). 7.0 T showed larger image quality variations with challenges especially in the TSE sequences. CONCLUSION: Our initial results of ultra-high-field ankle joint imaging demonstrate the improved depiction of ankle anatomy, fluid depositions, and cartilage defects. However imaging of edema-like bone lesions remains challenging at ultra-high magnetic field strength, and TSE coverage in particular is limited by the specific absorption rate.
    Skeletal Radiology 06/2012; · 1.74 Impact Factor
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    ABSTRACT: To evaluate the diagnostic performance of T2-weighted magnetic resonance (MR) cholangiopancreatography pulse sequences in comparison with MR cholangiopancreatography sequences combined with nonenhanced T1-weighted images in the detection of biliary cast syndrome in liver transplant recipients. This retrospective study was conducted in accordance with the declaration of Helsinki. Institutional review board approval was obtained. MR images in 95 patients who were examined after liver transplantation and who presented with symptoms of biliary obstruction were examined. Two separate sets of images, MR cholangiopancreatograms and MR cholangiopancreatograms plus T1-weighted images, were evaluated independently by three readers. Sensitivities, specificities, and positive and negative predictive values for biliary cast syndrome were calculated, and receiver operating characteristic curves were generated. The results of endoscopic retrograde cholangiopancreatography served as the reference standard. To determine interobserver agreement, κ values were calculated. Cast appeared hyperintense on nonenhanced T1-weighted images. Sensitivities for T2-weighted MR cholangiopancreatography data alone were 0.65, 0.70, and 0.55 for the three readers. Adding unenhanced T1-weighted images resulted in sensitivities of 0.95, 0.90, and 0.90, respectively. Specificities for MR cholangiopancreatography alone and for MR cholangiopancreatography plus T1-weighted images were high on average (0.98, 0.97, and 0.97 vs 1.0 for all readers, respectively). Interobserver agreement was good for T2-weighted MR cholangiopancreatography (κ for readers 1 and 2 = 0.589, κ for readers 2 and 3 = 0.593, κ for readers 1 and 3 = 0.734) and was excellent for MR cholangiopancreatography plus T1-weighted images (κ for readers 1 and 2 = 0.806, κ for readers 2 and 3 = 0.881, κ for readers 1 and 3 = 0.848). The combination of T2-weighted MR cholangiopancreatography and T1-weighted imaging yields higher diagnostic performance than MR cholangiopancreatography alone. Therefore, readers evaluating liver MR images with regard to biliary complications after liver transplantation should also look at the bile ducts on unenhanced T1-weighted images, as biliary cast might be more easily depicted on these images.
    Radiology 05/2012; 263(2):429-36. · 6.34 Impact Factor
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    ABSTRACT: To assess the survival of patients with hepatic uveal melanoma metastases undergoing sequential transarterial hepatic chemoperfusion. 61 patients (mean age, 60.3 ± 13.8 y) underwent a total of 249 hepatic chemoperfusion procedures (mean: 4 chemoperfusion procedures; range, 1-7 chemoperfusion procedures; standard deviation, 2.3 chemoperfusion procedures). All patients started with melphalan. In the case of progressive disease, melphalan was replaced by a different chemoperfusion agent. 38 patients were treated with melphalan only, 23 patients were treated with a combination of melphalan and other drugs. The median overall survival time was calculated for the overall population and several sub-groups. Differences in the survival rate between the sub-groups were assessed for statistical significance. The complication rate was assessed. The median overall survival of the entire population was 10 months. The patients in the subgroups with a maximum number of 9 hepatic metastases as well as the patients in the subgroup without extrahepatic metastases at the beginning of therapy survived significantly longer than patients with more than 9 metastases/extrahepatic metastases (p = 0.019, p = 0.008). One patient (0.4%) died from liver failure after initial infusion of melphalan. Intraarterial sequential hepatic chemoperfusion offers a minimally invasive treatment in patients with hepatic uveal melanoma metastases with good survival times and an acceptable major complication rate.
    RöFo - Fortschritte auf dem Gebiet der R 12/2011; 183(12):1151-60. · 2.76 Impact Factor
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    ABSTRACT: Two different forms of biliary anastomosis can be created in patients undergoing liver transplantation: (a) bilio-digestive anastomoses or (b) choledocho-choledochostomy. Aim of this study was to assess the accuracy of MR cholangiopancreatography (MRCP) for the depiction of biliary stenoses in liver transplant patients depending on the type of biliary anastomosis. 24 liver transplant patients with clinical suspicion of biliary stenosis were studied (each 12 with bilio-digestive anastomosis/choledocho-choledochostomy). MRCP was performed on a 1.5 T scanner (Magnetom Avanto, Siemens) including 2D single shot RARE, 2D T2w HASTE, TrueFISP and 3D high-resolution navigator corrected sequences. Presence of (a) anastomotic stenoses (AST) and (b) NAS (non-anastomotic strictures) were assessed. Percutaneous transhepatic cholangiography (PTC) or endoscopic retrograde cholangiopancreatography (ERCP) were performed within 48h after MRCP and served as the standard of reference. In patients with bilio-digestive anastomoses sensitivities of MRCP for the detection of AST and NAS amounted to 50% and 67%, respectively with specificity values of 83% and 50%. In patients with choledocho-chledochostomy sensitivities (AST: 100%, NAS: 100%) and specificities (AST: 100%, NAS: 88%) were significantly higher. Biliary strictures after liver transplantation can be accurately detected by MRCP in patients after choledocho-chledochostomy. However, the diagnostic value of MRCP is lower if liver transplantation was performed in combination with a bilio-digestive anastomosis. This may be due to the less exact depiction of the anastomosis in the bowel wall. Thus, it is crucial to know the type of biliary anastomosis before choosing a diagnostic procedure.
    European journal of radiology 11/2011; 80(2):e20-8. · 2.65 Impact Factor
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    ABSTRACT: To assess the survival time of patients with HCC following transarterial chemoembolization performed in a highly selective and sequential way. 124 HCC patients (102 male, 22 female; mean age 63±11 years) treated with selective and sequential chemoembolization at a single center were included. Selective chemoembolization was performed through a coaxially introduced microcatheter in a segmental or subsegmental hepatic artery. Treatment was stopped after complete stasis of the blood flow in the tumor-feeding vessel. The primary endpoint of the study was overall survival. The median overall survival of the entire patient population was 27.2 months (mo) (±8.9 mo, 95% CI 9.8 mo, 44.6 mo). When stratified according to liver function the median survival was 46.1 mo (±9.0 mo; 95% CI 28.5 mo, 63.7 mo) for Child-Pugh A and 11.1 mo (±4.3 mo; 95% CI 2.7 mo, 19.5 mo) for Child-Pugh B (p<.001). The median survival was 46.1 mo (±16.6 mo; 95% CI 13.5 mo, 78.7 mo) for BCLC stage A, 19.7 mo (±2.6 mo; 95% CI 14.6 mo, 24.8 mo) for BCLC stage B, and 14.4 mo (±5.0 mo; 95% CI 4.5 mo, 24.3 mo) for BCLC stage C (p<.01). Selective and sequential chemoembolization offers long survival times in patients with HCC. Those patients with preserved liver function benefit more than patients with limited liver reserve.
    European journal of radiology 10/2011; 81(9):2290-7. · 2.65 Impact Factor
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    ABSTRACT: The aim of this study was to investigate the feasibility of dynamic contrast-enhanced 7T MRI of the liver using an eight-channel radiofrequency (RF) transmit/receive body-coil. 16 healthy subjects were examined on a 7T MR system utilizing a custom-built eight-channel RF body-coil suitable for RF-shimming. The following data were acquired: (1) steady state free precession imaging, (2) T2w turbo spin echo imaging, (3) T1w in and opposed-phase imaging, (4) T1w 3D FLASH images pre-contrast and in arterial, portal-venous and venous phase and (5) a fat-saturated pre- and post-contrast 2D FLASH sequence. Visual evaluation of (1) the delineation of liver vasculature, (2) the overall image quality, and (3) artifact presence and consequent image impairment was performed. SNR of the liver parenchyma was measured for the contrast-enhanced 2D and 3D FLASH sequences. For statistical analysis, a Wilcoxon-Rank Test was used. Best delineation of non-enhanced liver vasculature and overall image quality was found for 2D FLASH MRI, with only slight improvement in vessel conspicuity after the application of contrast media. T2-weighted TSE imaging remained strongly impaired, falling short of diagnostic relevance and precluding a clinical application. Our results demonstrate the feasibility and diagnostic potential of dedicated contrast-enhanced 7T liver MRI as well as the potential for non-contrast-enhanced angiographic application.
    European journal of radiology 08/2011; · 2.65 Impact Factor
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    ABSTRACT: A study on subjective perception has been carried out in order to gain further insight into subjective discomfort and sensations experienced during 7 T magnetic resonance imaging (MRI). This study provides information about subjective acceptance, which is essential if 7 T MRI is to become a clinical diagnostic tool. Of 573 subjects who underwent 7 T MRI, 166 were also examined at 1.5 T, providing a means of discriminating field-dependent discomfort. All subjects judged sources of discomfort and physiological sensations on an 11-point scale (0 = no side effects, 10 = intolerable side effects) and scores were analyzed separately for exam phases, with and without table movement at each field strength. Results revealed that 7 T MRI was, in general, judged more uncomfortable than 1.5 T; however, most subjects rated the effects as being non-critical (mean scores between 0.5 and 3.5). Significant differences were detected regarding vertigo and sweating between subjects positioned "head-first" and "feet-first" at 7 T (worse in "head-first") and between 7 and 1.5 T (worse at 7 T), with the effects being more pronounced in the moving compared to the stationary table position. The most unpleasant factor at 7 T was the extensive examination duration, while potentially field-dependent sensations were rated less bothersome. In summary, our study indicates that although certain sensations increase at 7 T compared to 1.5 T, they are unlikely to hinder the use of 7 T MRI as a clinical diagnostic tool.
    Bioelectromagnetics 05/2011; 32(8):610-9. · 2.02 Impact Factor
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    ABSTRACT: To investigate the feasibility of 7T MR imaging of the kidneys utilising a custom-built 8-channel transmit/receive radiofrequency body coil. In vivo unenhanced MR was performed in 8 healthy volunteers on a 7T whole-body MR system. After B(0) shimming the following sequences were obtained: 1) 2D and 3D spoiled gradient-echo sequences (FLASH, VIBE), 2) T1-weighted 2D in and opposed phase 3) True-FISP imaging and 4) a T2-weighted turbo spin echo (TSE) sequence. Visual evaluation of the overall image quality was performed by two radiologists. Renal MRI at 7T was feasible in all eight subjects. Best image quality was found using T1-weighted gradient echo MRI, providing high anatomical details and excellent conspicuity of the non-enhanced vasculature. With successful shimming, B(1) signal voids could be effectively reduced and/or shifted out of the region of interest in most sequence types. However, T2-weighted TSE imaging remained challenging and strongly impaired because of signal heterogeneities in three volunteers. The results demonstrate the feasibility and diagnostic potential of dedicated 7T renal imaging. Further optimisation of imaging sequences and dedicated RF coil concepts are expected to improve the acquisition quality and ultimately provide high clinical diagnostic value.
    European Radiology 04/2011; 21(4):841-9. · 4.34 Impact Factor
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    ABSTRACT: To evaluate 7T MRI in the assessment of cerebrovascular alterations as seen in vascular dementia by means of detection of cerebral microbleeds (CMB) and depiction of white matter lesions (WML). 7T imaging was evaluated with respect to 1.5T. Ten healthy volunteers and 10 patients with CMBs and/or WMLs were examined at 1.5T and 7T using gradient-echo (T2*, SWI) and turbo-spin-echo sequences (FLAIR). Comparisons of image quality, CMB and WML detection rates between sequences and field strengths were performed. Using high-resolution SWI at 7T 129 CMBs were detected compared to 75 at 1.5T using clinical SWI. With T2* at 7T 101 CMBs could be detected (33 CMBs at 1.5T). Lesion sizes were significantly larger for higher field strength. FLAIR images at 7T highlighted WMLs known from 1.5T with comparable extent. Gray and white matter contrast in FLAIR was slightly better at 1.5T, whereas image resolution and contrast of the WMLs to surrounding tissue was higher at 7T. By means of higher sensitivity for CMBs, 7T (SWI, T2*) might have significant impact on the early detection, diagnosis, and optimized antithrombotic therapy of cerebrovascular patients (eg, vascular dementia) in the future. Given the current state of technical development, 7T is approximately on par with 1.5T in the depiction of WMLs and their distribution, but holds the potential for future improvements.
    Journal of Magnetic Resonance Imaging 04/2011; 33(4):782-91. · 2.57 Impact Factor
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    ABSTRACT: At 1.5 T, real-time MRI of joint movement has been shown to be feasible. However, 7 T, provides higher SNR and thus an improved potential for parallel imaging acceleration. The purpose of this work was to build an open, U-shaped eight-channel transmit/receive microstrip coil for 7 T MRI to enable high-resolution and real-time imaging of the moving ankle joint. A U-shaped eight-channel transmit/receive array for the human ankle was built. S-parameters and g-factor were measured. SAR calculations of different ankle postures were performed to ensure patient safety. Inhomogeneities in the transmit field consequent to the open design were compensated for by the use of static RF shimming. High-resolution and real-time imaging was performed in human volunteers. The presented array showed good performance with regard to patient comfort and image quality. High acceleration factors of up to 4 are feasible without visible acceleration artifacts. Reasonable image homogeneity was achieved with RF shimming. Open, noncylindrical designs for transmit/receive coils are practical at 7 T and real-time imaging of the moving joint is feasible with the presented coil design.
    Medical Physics 03/2011; 38(3):1162-7. · 2.91 Impact Factor
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    ABSTRACT: MRI plays a leading diagnostic role in assessing the musculoskeletal (MSK) system and is well established for most questions at clinically used field strengths (up to 3 T). However, there are still limitations in imaging early stages of cartilage degeneration, very fine tendons and ligaments, or in locating nerve lesions, for example. 7 T MRI of the knee has already received increasing attention in the current published literature, but there is a strong need to develop new radiofrequency (RF) coils to assess more regions of the MSK system. In this work, an eight-channel transmit/receive RF array was built as a multipurpose coil for imaging some of the thus far neglected regions. An extensive coil characterization protocol and first in vivo results of the human wrist, shoulder, elbow, knee, and ankle imaged at 7 T will be presented. Eight surface loop coils with a dimension of 6 x 7 cm2 were machined from FR4 circuit board material. To facilitate easy positioning, two coil clusters, each with four loop elements, were combined to one RF transmit/receive array. An overlapped and shifted arrangement of the coil elements was chosen to reduce the mutual inductance between neighboring coils. A phantom made of body-simulating liquid was used for tuning and matching on the bench. Afterward, the S-parameters were verified on a human wrist, elbow, and shoulder. For safety validation, a detailed compliance test was performed including full wave simulations of the RF field distribution and the corresponding specific absorption rate (SAR) for all joints. In vivo images of four volunteers were assessed with gradient echo and spin echo sequences modified to obtain optimal image contrast, full anatomic coverage, and the highest spatial resolution within a reasonable acquisition time. The performance of the RF coil was additionally evaluated by in vivo B1 mapping. A comparison of B1 per unit power, flip angle distribution, and anatomic images showed a fairly homogeneous excitation for the smaller joints (elbow, wrist, and ankle), while for the larger joints, the shoulder and especially the knee, B1 inhomogeneities and limited penetration depth were more pronounced. However, the greater part of the shoulder joint could be imaged. In vivo images rendered very fine anatomic details such as fascicles of the median nerve and the branching of the nerve bundles. High-resolution images of cartilage, labrum, and tendons could be acquired. Additionally, turbo spin echo (TSE) and inversion recovery sequences performed very well. This study demonstrates that the concept of two four-channel transmit/receive RF arrays can be used as a multipurpose coil for high-resolution in vivo MR imaging of the musculoskeletal system at 7 T. Not only gradient echo but also typical clinical and SAR-intensive sequences such as STIR and TSE performed well. Imaging of small structures and peripheral nerves could in particular benefit from this technique.
    Medical Physics 12/2010; 37(12):6368-76. · 2.91 Impact Factor
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    ABSTRACT: Recovery of aneurysm induced CNP after endosaccular coiling has been reported in the literature. The aim of this study was to assess in detail the parameters that affect the outcome after endovascular treatment of ophthalmoplegic aneurysms due CNP. Between November 1999 and March 2008, 30 consecutive patients (8 men, 22 women; mean age, 54.9 years) presenting with CNP underwent endosaccular coiling with or without additional use of stents in the parent artery. Subarachnoid hemorrhage was present in 10 patients, whereas 20 patients had unruptured aneurysms. The mean size of the aneurysms was 10 mm. Initial CNP was complete in 11 patients and partial in 19. Mean follow-up after coiling was 19 months. The mean interval between the onset of CNP and aneurysm embolization was 48 days. Fifteen patients (50%) had complete recovery of oculomotor function, 12 had incomplete recovery (40%), and 3 (10%) remained unchanged after treatment. In 4 aneurysms (13.3%), 1 additional embolization was performed, whereas in 4 other aneurysms, 2 additional embolization procedures were necessary. Procedure-related permanent morbidity occurred in 2 patients (6.6%). Endosaccular coiling is an effective and safe method for the treatment of ophthalmoplegic aneurysms. Age, neck size, and time of treatment do not seem to constitute prognostic factors with respect to CNP recovery, though patients with small aneurysms, unruptured status, and/or location in the posterior circulation showed a tendency for better outcome. The degree of initial CNP was the only statistically significant prognostic factor concerning the final outcome, resulting in better recovery, in case of incomplete initial CNP.
    American Journal of Neuroradiology 11/2010; 32(2):276-82. · 3.17 Impact Factor
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    ABSTRACT: To investigate dual-energy CT of hypervascular liver lesions in patients with HCC. Forty patients with hepatocellular carcinomas were investigated with abdominal dual-energy CT. In each patient unenhanced and contrast-enhanced imaging with arterial und portovenous delay were performed. Hypervascular lesions were documented on arterial phase 80-kVp images, 140-kVp images, and the averaged arterial images by two radiologists. Subjective image quality (5-point scale, from 5 [excellent] to 1 [not interpretable]) was rated on all images. The mean number of hypervascular HCC lesions detected was 3.37 ± 1.28 on 80-kVp images (p < 0.05), 1.43 ± 1.13 on 140-kVp images (p < 0.05), and 2.57 ± 1.2 on averaged images. The image quality was 0.3 ± 0.5 for 80-kVp (p < 0.05), 1.6 ± 0.5 for 140-kVp (p < 0.05) and 3.2 ± 0.4 for the averaged images. Low-kVp images of dual-energy datasets are more sensitive in detecting hypervascular liver lesions. However, this increase in sensitivity goes along with a decrease in the subjective image quality of low-kVp images.
    European Radiology 10/2010; 21(4):738-43. · 4.34 Impact Factor
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    ABSTRACT: To compare the depiction of brain metastases of bronchial carcinomas on susceptibility-weighted and contrast-enhanced images with 7 T and at 1.5 T MRI. Twelve patients with brain metastases of bronchial carcinomas underwent 7 T and 1.5 T MRI. Minimum intensity projections (MinIP) of a 1.5 T SWI sequence (voxel size = 0.9 x 0.9 x 2.0 mm(3)) were compared to 7 T SWI MinIPs (voxel size = 0.4 x 0.4 x 1.5 mm(3)). A T 1-w 3D MPRAGE at 1.5 T (voxel size = 1 x 1 x 1 mm(3) after double-dose (DD) gadoterate meglumine, Gd-DOTA) was compared to a 7 T MPRAGE sequence (voxel size = 0.7 x 0.7 x x 0.7 mm(3), single dose (SD) Gd-DOTA) in all patients, and to DD Gd-DOTA in 6 patients after a 10 minute delay. The number of intracranial microhemorrhages in SWI MinIPs and the number of contrast-enhancing metastases in MPRAGE images were compared in each patient grouped into three size ranges (< or = 2 mm, > 2 mm and < 6 mm, > or = 6 mm) by two radiologists in consensus. In all 12 patients the 7 T SWI with spatially higher resolution allowed the identification of 87 versus 67 cerebral microhemorrhages at 1.5 T. 7 T T 1-w images after SD Gd-DOTA depicted 198 brain metastases versus 238 at 1.5 T after DD Gd-DOTA. After doubling the contrast dose in six patients, 4 additional brain metastases were identified at 7 T. Our preliminary results indicate that despite the higher spatial resolution the detection of brain metastases on 7 T MPRAGE images is almost equal to 1.5 T MPRAGE images. The 7 T SWI sequence with spatially higher resolution allowed the detection of 20 % more microhemorrhages in brain metastases compared to the 1.5 T SWI sequence.
    RöFo - Fortschritte auf dem Gebiet der R 09/2010; 182(9):764-72. · 2.76 Impact Factor
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    ABSTRACT: Magnetic resonance imaging (MRI) of rodents can be expected to be a growing application, particularly when translatory imaging research "from mouse to man" is envisioned. 7 T high-field human whole-body MR systems provide a powerful platform for high-resolution small animal imaging. For achieving adequate spatial resolution, dedicated radiofrequency coils have to be designed to provide the necessary signal-to-noise ratio (SNR). Two different multichannel transmit/receive radiofrequency (RF) arrays for high-resolution imaging of rodents on a human whole-body 7 T MR system have been developed and evaluated in comparative in vitro phantom experiments and in vivo experiments in rats. The first coil was a one-channel birdcage RF transmit/eight-channel loop RF receive phased-array coil; the second coil was an eight-channel RF transmit/receive stripline phased-array coil with inverted microstrip lines--A coil design that here is described for the first time for dedicated small animal MR imaging. Both coil setups provided the high SNR necessary for high-resolution MRI in rodents. The eight-channel loop RF array, with its larger inner diameter and transparent layout, provided better overall signal homogeneity and enabled easy visual monitoring; the eight-channel stripline RF array provided overall higher SNR and better parallel imaging acceleration performance. The results show that both coil designs are suitable for small animal imaging on 7 T whole-body systems; the preferred coil depends on the demands of the application.
    Medical Physics 05/2010; 37(5):2225-32. · 2.91 Impact Factor
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    ABSTRACT: To assess potential cognitive deficits under the influence of static magnetic fields at various field strengths some studies already exist. These studies were not focused on attention as the most vulnerable cognitive function. Additionally, mostly no magnetic resonance imaging (MRI) sequences were performed. In all, 25 right-handed men were enrolled in this study. All subjects underwent one MRI examination of 63 minutes at 1.5 T and one at 7 T within an interval of 10 to 30 days. The order of the examinations was randomized. Subjects were referred to six standardized neuropsychological tests strictly focused on attention immediately before and after each MRI examination. Differences in neuropsychological variables between the timepoints before and after each MRI examination were assessed and P-values were calculated Only six subtests revealed significant differences between pre- and post-MRI. In these tests the subjects achieved better results in post-MRI testing than in pre-MRI testing (P = 0.013-0.032). The other tests revealed no significant results. The improvement in post-MRI testing is only explicable as a result of learning effects. MRI examinations, even in ultrahigh-field scanners, do not seem to have any persisting influence on the attention networks of human cognition immediately after exposure.
    Journal of Magnetic Resonance Imaging 05/2010; 31(5):1061-6. · 2.57 Impact Factor

Publication Stats

587 Citations
187.74 Total Impact Points

Institutions

  • 2006–2013
    • University Hospital Essen
      • Institute of Diagnostic and Interventional Radiology and Neuroradiology
      Essen, North Rhine-Westphalia, Germany
  • 2008–2012
    • University of Duisburg-Essen
      • Erwin L. Hahn Institute for Magnetic Resonance Imaging
      Duisburg, North Rhine-Westphalia, Germany
    • Emory University
      • Department of Radiology
      Atlanta, GA, United States