G K von Schulthess

University of Zurich, Zürich, Zurich, Switzerland

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Publications (304)1095.54 Total impact

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    ABSTRACT: Background Hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) shows high potential for patients with oropharyngeal cancer. Dental implants can cause substantial artifacts in the oral cavity impairing diagnostic accuracy. Therefore, we evaluated new MRI sequences with multi-acquisition variable-resonance image combination (MAVRIC SL) in comparison to conventional high-bandwidth techniques and in a second step showed the effect of artifact size on MRI-based attenuation correction (AC) with a simulation study. Methods Twenty-five patients with dental implants prospectively underwent a trimodality PET/CT/MRI examination after informed consent was obtained under the approval of the local ethics committee. A conventional 3D gradient-echo sequence (LAVA-Flex) commonly used for MRI-based AC of PET (acquisition time of 14 s), a T1w fast spin-echo sequence with high bandwidth (acquisition time of 3.2 min), as well as MAVRIC SL sequence without and with increased phase acceleration (MAVRIC, acquisition time of 6 min; MAVRIC-fast, acquisition time of 3.5 min) were applied. The absolute and relative reduction of the signal void artifact was calculated for each implant and tested for statistical significance using the Wilcoxon signed-rank test. The effect of artifact size on PET AC was simulated in one case with a large tumor in the oral cavity. The relative difference of the maximum standardized uptake value (SUVmax) in the tumor was calculated for increasing artifact sizes centered over the second molar. Results The absolute reduction of signal void from LAVA-Flex sequences to the T1-weighted fast spin-echo (FSE) sequences was 416 mm2 (range 4 to 2,010 mm2) to MAVRIC 481 mm2 (range 12 to 2,288 mm2) and to MAVRIC-fast 486 mm2 (range 39 to 2,209 mm2). The relative reduction in signal void was significantly improved for both MAVRIC and MAVRIC-fast compared to T1 FSE (−75%/−78% vs. −62%, p max was negligible for artifacts of 0.5-cm diameter (−0.1%), but substantial for artifacts of 5.2-cm diameter (−33%). Conclusions MAVRIC-fast could become useful for artifact reduction in PET/MR for patients with dental implants. This might improve diagnostic accuracy especially for patients with tumors in the oropharynx and substantially improve accuracy of PET quantification.
    EJNMMI Physics. 12/2014; 1(1).
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    ABSTRACT: The aim of this study was to investigate the registration accuracy of a newly developed patient shuttle system that can integrate different scanners by patient transfer without repositioning for 'hardware'-based image fusion. We aimed to assess the registration accuracy of image fusion in two different settings: a trimodality PET/CT+MR system and a SPECT+CT system.
    Nuclear Medicine Communications 10/2014; 36(2). · 1.37 Impact Factor
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    ABSTRACT: (d)-(18)F-fluoromethyltyrosine (d-(18)F-FMT), or BAY 86-9596, is a novel (18)F-labeled tyrosine derivative rapidly transported by the l-amino acid transporter (LAT-1), with a faster blood pool clearance than the corresponding l-isomer. The aim of this study was to demonstrate the feasibility of tumor detection in patients with non-small cell lung cancer (NSCLC) or head and neck squamous cell cancer (HNSCC) compared with inflammatory and physiologic tissues in direct comparison to (18)F-FDG.
    Journal of Nuclear Medicine 09/2014; · 5.56 Impact Factor
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    ABSTRACT: The purpose of this study is to compare the PET performance between the PET/CT and a prototype integrated PET/MR for various reduced acquisition times. The image parameters to be evaluated are image quality, image sharpness, artifacts and noise. ROIs are drawn in the liver and brain’s white maEer to assess the SUV behaviour.
    Joint Medical Physics Conference SSRMP DGMP OGMP; 09/2014
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    ABSTRACT: This study concerns 3D ultra short-echo time (UTE) sequence testing and comparison to LAVA sequence for MR based attenuation correction for PET lung imaging. 3D UTE is advantageous over LAVA, being able to capture bone structures by its very short TE (~0.03 ms). Another advantage that is examined here, could be the detection and visualization of lung parenchyma density, as studies have already shown. Both these advantages could lead to more precise attribution of the linear attenuation coefficients of bone and lung structure.
    Joint Medical Physics Conference SSRMP DGMP ÖGMP; 09/2014
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    ABSTRACT: Purpose To assess the diagnostic performance of whole-body non-contrast material-enhanced positron emission tomography (PET)/magnetic resonance (MR) imaging and PET/computed tomography (CT) for staging and restaging of cancers and provide guidance for modality and sequence selection. Materials and Methods This study was approved by the institutional review board and national government authorities. One hundred six consecutive patients (median age, 68 years; 46 female and 60 male patients) referred for staging or restaging of oncologic malignancies underwent whole-body imaging with a sequential trimodality PET/CT/MR system. The MR protocol included short inversion time inversion-recovery (STIR), Dixon-type liver accelerated volume acquisition (LAVA; GE Healthcare, Waukesha, Wis), and respiratory-gated periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER; GE Healthcare) sequences. Primary tumors (n = 43), local lymph node metastases (n = 74), and distant metastases (n = 66) were evaluated for conspicuity (scored 0-4), artifacts (scored 0-2), and reader confidence on PET/CT and PET/MR images. Subanalysis for lung lesions (n = 46) was also performed. Relevant incidental findings with both modalities were compared. Interreader agreement was analyzed with intraclass correlation coefficients and κ statistics. Lesion conspicuity, image artifacts, and incidental findings were analyzed with nonparametric tests. Results Primary tumors were less conspicuous on STIR (3.08, P = .016) and LAVA (2.64, P = .002) images than on CT images (3.49), while findings with the PROPELLER sequence (3.70, P = .436) were comparable to those at CT. In distant metastases, the PROPELLER sequence (3.84) yielded better results than CT (2.88, P < .001). Subanalysis for lung lesions yielded similar results (primary lung tumors: CT, 3.71; STIR, 3.32 [P = .014]; LAVA, 2.52 [P = .002]; PROPELLER, 3.64 [P = .546]). Readers classified lesions more confidently with PET/MR than PET/CT. However, PET/CT showed more incidental findings than PET/MR (P = .039), especially in the lung (P < .001). MR images had more artifacts than CT images. Conclusion PET/MR performs comparably to PET/CT in whole-body oncology and neoplastic lung disease, with the use of appropriate sequences. Further studies are needed to define regionalized PET/MR protocols with sequences tailored to specific tumor entities. © RSNA, 2014 Online supplemental material is available for this article.
    Radiology 08/2014; · 6.21 Impact Factor
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    ABSTRACT: The purpose of this study was to analyze whether diffusion-weighted imaging (DWI) adds significant information to positron emission tomography/magnetic resonance imaging (PET/MRI) on lesion detection and characterization in head and neck cancers.
    European journal of nuclear medicine and molecular imaging 08/2014; · 5.22 Impact Factor
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    ABSTRACT: This study concerns 3D ultra short-echo time (UTE) sequence testing and comparison to LAVA sequence for MR based attenuation correction for PET lung imaging [1]. 3D UTE is advantageous over LAVA, being able to capture bone structures by its very short TE (~0.03 ms). Another advantage that is examined here, could be the detection and visualization of lung parenchyma density, as studies have already shown [2]. Both these advantages could lead to more precise attribution of the linear attenuation coefficients of bone and lung structure. The study was conducted on a GE Discovery MR750w 3T scanner. Gradient echo sequences used are dual-echo Liver Acquisition with Volume Acquisition (LAVA) and 3D UTE Cones. A healthy volunteer and a patient with pleural effusion were scanned with both sequences. For LAVA the parameters are: 15 sec breath-hold acquisition, TR/TE/FA 4.4ms/2.6ms/12 degrees, FOV 30*30*30 cm, res/slice 2mm/ 4mm. For Cones: 3 min prospective gated acquisition, TR/TE/FA 4ms/0.028ms/7 degrees, FOV 30*30*30 cm, res/slice 1.6mm/ 4mm. The images are set to same contrast window width.
    SNMMI 2014; 06/2014
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    ABSTRACT: INTRODUCTION: MR lung imaging is challenging due to lung inherent low proton density, very short T2*, large susceptibiliy effects and respiratory motion that can introduce artefacts and degrade image quality. Standard methods to avoid respiratory motion artefacts include external devices like respiration belts [1]. Ultra-short Time Echo (UTE) sequences can be used in free-breathing acquisitions leading to satisfactory image quality. Image quality can be further improved if a self-gating navigator is applied, taking advantage of the DC signal inherent oversampling in 3D Radial trajectory sequences [2-4]. Projected Radial (PR) imaging presents robustness to motion. Other advantages involve not using extra rf pulses for determining navigators and external devices [5]. We propose a retrospective respiratory gating implementation based on the detection of the respiration profile by DC signal and gating of the end-expiration phase. METHODS: Data from healthy volunteer subjects with normal breathing cycle were acquired on a GE Discovery MR750w 3T scanner. The acquisition time per scan was 5.52 minutes with a 3D PR, fast spoiled gradient echo pulse sequence: TR=7.6 ms, TE=0.01 ms, FA=6 o , FOV=30*30*26.5 cm 3 , isotropic resolution=1.6 mm and 160 slices. The central k-space point, containing the DC signal from one of the coil elements that are near to the diaphragm and can record lung motion was chosen for the navigator extraction. Four identical scans were acquired and the DC navigator was extracted from each of them. After, superimposing and rescaling all 4 navigators, the interleaves corresponding to end-expiration phase were selected for all coils. The final data for reconstruction had the size of one acquisiton with a mixture of interleaves from all scans that meet the condition of the highest values of the end-expiration phase. Reconstruction was done offline using MATLAB (The Mathworks, Natick, USA). RESULTS: Figure 1a shows the extraction of the best DC signal from the coil that is sensitive near the diaphragm. DC detects the respiration motion with higher amplitude representing the end-expiration phase. Figure 1b shows the four DC signals with the DC navigator selecting only maximum value inteleaves that correspond to end-expiration. 81% of the interleaves used corresponded to end-expiration phase. Figure 2 depicts coronal planes before and after gating. The artifacts and blurring effect are reduced in both Maximum Intensity Projection and single slice planes. Deep bronchial branches, pneumonic arteries and vessels are imaged with improved contrast. Structures near the diaphragm are better defined, avoiding motion blurring.
    ISMRM 2014; 05/2014
  • Gustav K von Schulthess, Patrick Veit-Haibach
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    ABSTRACT: Many groups attempt to optimize imaging protocols on PET/MR imaging systems. Although research protocols may take as long as 60-90 min, much more efficient clinical workflows are needed to achieve cost-effective examination times of less than 1 h. Considering these difficulties, simultaneous PET/MR imaging is an intriguing research tool, but its clinical applications are uncertain or just beginning to emerge. However, unlike PET/CT, in which the options for various CT protocols are limited, the MR imaging portion of PET/MR imaging can be extended arbitrarily depending on the MR pulse sequences chosen. For PET/MR imaging to be complementary, feasible, and somewhat competitive with PET/CT, image acquisition times should ideally be limited to 30 min. The purposes of this article are to help the reader to understand the critical workflow issues in simultaneous PET/MR imaging in comparison with sequential PET/MR imaging and to learn how to optimize an imaging examination. Current knowledge toward this goal is summarized.
    Journal of Nuclear Medicine 05/2014; · 5.56 Impact Factor
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    ABSTRACT: Positron emission tomography (PET)/MRI combines the functional ability of PET and the high soft tissue contrast of MRI. The aim of this study was to assess contrast-enhanced (ce)PET/MRI compared to cePET/CT in patients with suspected recurrence of head and neck cancer (HNC). Eighty-seven patients underwent sequential cePET/CT and cePET/MRI using a trimodality PET/CT-MRI set-up. Diagnostic accuracy for the detection of recurrent HNC was evaluated using cePET/CT and cePET/MRI. Furthermore, image quality, presence of unclear (18)F-fluorodeoxy-D-glucose (FDG) findings of uncertain significance and the diagnostic advantages of use of gadolinium contrast enhancement were analysed. cePET/MRI showed no statistically significant difference in diagnostic accuracy compared to cePET/CT (91.5 vs 90.6 %). Artefacts' grade was similar in both methods, but their location was different. cePET/CT artefacts were primarily located in the suprahyoid area, while on cePET/MRI, artefacts were more equally distributed among the supra and infrahyoid neck regions. cePET/MRI and cePET/CT showed 34 unclear FDG findings; of those 11 could be solved by cePET/MRI and 5 by cePET/CT. The use of gadolinium in PET/MRI did not yield higher diagnostic accuracy, but helped to better define tumour margins in 6.9 % of patients. Our data suggest that cePET/MRI may be superior compared to cePET/CT to specify unclear FDG uptake related to possible tumour recurrence in follow-up of patients after HNC. It seems to be the modality of choice for the evaluation of the oropharynx and the oral cavity because of a higher incidence of artefacts in cePET/CT in this area mainly due to dental implants. However, overall there is no statistically significant difference.
    European Journal of Nuclear Medicine 02/2014; · 4.53 Impact Factor
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    ABSTRACT: Considering PET/MR imaging as a whole-body staging tool, scan time restrictions in a single body area are mandatory for the cost-effective clinical operation of an integrated multimodality scanner setting. It has to be considered that (18)F-FDG already acts as a contrast agent and that under certain circumstances MR contrast may not yield additional clinically relevant information. The concept of the present study was to understand which portions of the imaging information enhance the sensitivity and specificity of the hybrid examination and which portions are redundant. One hundred fifty consecutive patients referred for primary staging or restaging of head and neck cancer underwent sequential whole-body (18)F-FDG PET with CT-based attenuation correction, contrast-enhanced (ce) CT, and conventional diagnostic MR imaging of the head and neck in a trimodality PET/CT-MR system. Assessed were image quality, lesion conspicuity, diagnostic confidence, and the benefit of additional coronal and sagittal imaging planes in cePET/CT, PET/MR imaging with only T2-weighted fat-suppressed images (T2w PET/MR imaging), and cePET/MR imaging. In 85 patients with at least 1 PET-positive lesion, 162 lesions were evaluated. Similar robustness was found for CT and MR image quality. T2w PET/MR imaging performed similarly to (metastatic lymph nodes) or better than (primary tumors) cePET/CT in the morphologic characterization of PET-positive lesions and permitted the diagnosis of necrotic or cystic lymph node metastasis without application of intravenous contrast medium. CePET/MR imaging yielded a higher diagnostic confidence for accurate lesion conspicuity (especially in the nasopharynx and in the larynx), infiltration of adjacent structures, and perineural spread. The results of the present study provide evidence that PET/MR imaging can serve as a legitimate alternative to PET/CT in the clinical workup of patients with head and neck cancers. Intravenous MR contrast medium may be applied only if the exact tumor extent or infiltration of crucial structures is of concern (i.e., preoperatively) or if perineural spread is anticipated. In early assessment of the response to therapy, in follow-up examinations, or in a whole-body protocol for non-head and neck tumors, T2w PET/MR imaging may be sufficient for coverage of the head and neck. The additional MR scanning time may instead be used for advanced MR techniques to increase the specificity of the hybrid imaging examination.
    Journal of Nuclear Medicine 02/2014; · 5.56 Impact Factor
  • Annals of the Rheumatic Diseases 01/2014; 71(Suppl 3):606-606. · 9.27 Impact Factor
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    ABSTRACT: To compare the accuracy of PET/MR imaging with that of FDG PET/CT and to determine the MR sequences necessary for the detection of liver metastasis using a trimodality PET/CT/MR set-up. Included in this single-centre IRB-approved study were 55 patients (22 women, age 61 ± 11 years) with suspected liver metastases from gastrointestinal cancer. Imaging using a trimodality PET/CT/MR set-up (time-of-flight PET/CT and 3-T whole-body MR imager) comprised PET, low-dose CT, contrast-enhanced (CE) CT of the abdomen, and MR with T1-W/T2-W, diffusion-weighted (DWI), and dynamic CE imaging. Two readers evaluated the following image sets for liver metastasis: PET/CT (set A), PET/CECT (B), PET/MR including T1-W/T2-W (C), T1-W/T2-W with either DWI (D) or CE imaging (E), and a combination (F). The accuracy of each image set was determined by receiver-operating characteristic analysis using image set B as the standard of reference. Of 120 liver lesions in 21/55 patients (38 %), 79 (66 %) were considered malignant, and 63/79 (80 %) showed abnormal FDG uptake. Accuracies were 0.937 (95 % CI 89.5 - 97.9 %) for image set A, 1.00 (95 % CI 99.9 - 100.0 %) for set C, 0.998 (95 % CI 99.4 - 100.0 %) for set D, 0.997 (95 % CI 99.3 - 100.0 %) for set E, and 0.995 (95 % CI 99.0 - 100.0 %) for set F. Differences were significant for image sets D - F (P < 0.05) when including lesions without abnormal FDG uptake. As shown by follow-up imaging after 50 - 177 days, the use of image sets D and both sets E and F led to the detection of metastases in one and three patients, respectively, and further metastases in the contralateral lobe in two patients negative on PET/CECT (P = 0.06). PET/MR imaging with T1-W/T2-W sequences results in similar diagnostic accuracy for the detection of liver metastases to PET/CECT. To significantly improve the characterization of liver lesions, we recommend the use of dynamic CE imaging sequences. PET/MR imaging has a diagnostic impact on clinical decision making.
    European Journal of Nuclear Medicine 12/2013; · 4.53 Impact Factor
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    ABSTRACT: PURPOSE To assess and to compare the diagnostic accuracy of PET/CT and PET/MRI in primary and metastatic gynaecological malignancies. METHOD AND MATERIALS 13 patients (13 female, mean age: 64, range 55-76years) with different primary and recurrent gynaecological diseases underwent a contrast-enhanced tri-modality PET/CT-MRI examination (PET/CT D 690 and 3T MRI 750W, GE Healthcare). Patients were first injected with an average of 320 MBq F18-FDG and then rested for 30 minutes. Then, a full diagnostic, contrast-enhanced MRI of the abdomen and pelcis, based on the current guidelines, was acquired with the following sequences: coronal T2 SSFSE pelvis, axial T2 SSFSE liver, axial T1 LaveFlex whole abdomen, axial diffusion pelvis, sagittal/axial T2 propeller pelvis, sag/axial T1 LavaFlex post contrast whole abomden. After the MRI, patients were transferred on a dedicated shuttle to the PET/CT. Here, a standard PET/CT with /without intravenous contrast media was acquired (FOV mid-thigh to the vertex of the skull. CT: 50-79 mAs/slice, automated dose modulation 120 kVp, 3.75 mm slice thickness. PET: 3D mode, 2 minutes/bed, iterative reconstruction with 3 iterations, 18 subsets). All data were evaluated on a commercially available workstation and can be displayed as PET, CT, PET/CT and PET/MRI. PET/MRI and PET/CT were evaluated concerning detection and conspicuity of the primary tumor, lymph node metastases and distant metastases. Readers also evaluated if the PET/MRI revealed relevant additional information compared to PET/CT. RESULTS Acquisition of PET/CT-MRI and PET/CT vs. PET/MRI evaluation was feasible in all patients. Concerning the primary tumour, the PET/CT was superior in 2 cases, PET/MRI in 5 cases, concerning lymph nodes PET/CT was superior in 2 cases, PET/MRI in 2 cases, in abdominal metastases PET/CT was superior in 2 cases, PET/MRI in none. PET/CT overall showed additional relevant additional information in 9 cases mainly concerning distant metastases, while PET/MRI showed relevant additional information in 3 cases concerning the primary tumour. CONCLUSION PET/MRI is well feasible within a tri-modality PET/CT-MRI system. The PET/MRI shows mainly advantages concerning the evaluation of the pimary tumor/local pelvic situation while the PET/CT has advantages concerning distant metastases. CLINICAL RELEVANCE/APPLICATION PET/MRI might be eligible to replace PET/CT in the work-up of OB-Gyn cancers.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
  • Gustav K von Schulthess
    Journal of Magnetic Resonance Imaging 09/2013; 40(2). · 2.57 Impact Factor
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    ABSTRACT: OBJECTIVES: The purpose of this study was to evaluate if positron emission tomography (PET)/magnetic resonance imaging (MRI) with just one gradient echo sequence using the body coil is diagnostically sufficient compared with a standard, low-dose non-contrast-enhanced PET/computed tomography (CT) concerning overall diagnostic accuracy, lesion detectability, size and conspicuity evaluation. METHODS AND MATERIALS: Sixty-three patients (mean age 58 years, range 19-86 years; 23 women, 40 men) referred for either staging or restaging/follow-up of various malignant tumours (malignant melanoma, lung cancer, breast cancer, Hodgkin's lymphoma, non-Hodgkin's lymphoma, CUP, gynaecology tumours, pleural mesothelioma, oesophageal cancer, colorectal cancer, stomach cancer) were prospectively included. Imaging was conducted using a tri-modality PET/CT-MR set-up (full ring, time-of-flight Discovery PET/CT 690, 3 T Discovery MR 750, both GE Healthcare, Waukesha, WI). All patients were positioned on a dedicated PET/CT- and MR-compatible examination table, allowing for patient transport from the MR system to the PET/CT without patient movement. In accordance with RECIST 1.1 criteria, measurements of the maximum lesion diameters on CT and MR images were obtained. In lymph nodes, the short axis was measured. A four-point scale was used for assessment of lesion conspicuity: 1 (>25 % of lesion borders definable), 2 (25-50 %), 3 (50-75 %) and 4 (>75 %). For each lesion the corresponding anatomical structure was noted based on anatomical information of the spatially co-registered PET/CT and PET/MRI image sections. Additionally, lesions were divided into three categories: "tumour mass", "lymph nodes" and "lesions". Differences in overall lesion detectability and conspicuity in PET/CT and PET/MRI, as well as differences in detectability based on the localisation and lesion type, were analysed by Wilcoxon signed rank test. RESULTS: A total of 126 PET-positive lesions were evaluated. Overall, no statistically significant superiority of PET/CT over PET/MRI or vice versa in terms of lesion conspicuity was found (p = 0.095; mean score CT 2.93, mean score MRI 2.75). A statistically significant superiority concerning conspicuity of PET/CT over PET/MRI was found in pulmonary lesions (p = 0.016). Additionally, a statistically significant superiority of PET/CT over PET/MRI in "lymph nodes" regarding lesion conspicuity was also found (p = 0.033). A higher mean score concerning bone lesions were found for PET/CT compared with PET/MRI; however, these differences did not achieve statistical significance. CONCLUSION: Overall, PET/MRI with body coil acquisition does not match entirely the diagnostic accuracy of standard low-dose PET/CT. Thus, it might only serve as a back-up solution in very few patients. Overall, more time needs to be invested on the MR imaging part (higher matrix, more breath-holds, additional surface coil acquired sequences) to match up with the standard low-dose PET/CT. MAIN MESSAGES : • Evaluation of whether PET/MRI with one sequence using body coil is diagnostically sufficient compared with PET/CT • PET/MRI with body coil does not match entirely the diagnostic accuracy of standard low-dose PET/CT • PET/MRI might only serve as a backup solution in patients.
    Insights into imaging. 05/2013; 4(4).
    This article is viewable in ResearchGate's enriched format
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    ABSTRACT: Although clinical positron emission tomography (PET)/computed tomography (CT) applications were obvious and have completely replaced PET in oncology, clinical applications of PET/magnetic resonance (MR) are currently not clearly defined. This is due to the lack of clinical data, which is mainly because PET/MR technology is not clinically mature at this point. Open issues are technical and concern ease of obtaining PET attenuation correction maps, dealing with, for example, MR surface coil metal in the PET field-of-view and appropriate workflows leading to a cost-effective examination. All issues can be circumvented by using a shuttle-connected PET/CT-MR system, but the penalty is that simultaneous PET and MR imaging are not possible and potential motion between examinations may occur. Clinically, some systems installed worldwide start to have a reasonable bulk of clinical data. Preliminary results suggest that in oncology, PET/MR may have advantages over PET/CT in head and neck imaging. In liver imaging, more PET-positive lesions are seen on MR than on CT, but that does not mean that PET/MR is superior to PET/CT. Possibly in some settings where a contrast-enhanced PET/CT is needed to be diagnostic, PET/MR can be done without contrast media. Although PET/CT has virtually no role in brain imaging, this may be an important domain for PET/MR, particularly in dementia imaging. The role of PET/MR in the heart is as yet undefined, and much research will have to be done to elucidate this role. At this point, it is also not clear where the simultaneity afforded by a fully integrated PET/MR is really needed. Sequential data acquisition even on separate systems and consecutive software image fusion may well be appropriate. With the increasing installed base of systems, clinical data will be forthcoming and define more clearly where there is clinical value in PET/MR at an affordable price.
    Seminars in nuclear medicine 01/2013; 43(1):3-10. · 3.96 Impact Factor
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    ABSTRACT: OBJECTIVE: The objective of this study was to prospectively compare the detection rate, the location, and the size of pulmonary nodules in low-dose computed tomography (CT) and in magnetic resonance (MR) imaging with a 3-dimensional (3D) dual-echo gradient-echo (GRE) pulse sequence using a trimodality positron emission tomography (PET)/CT-MR setup. METHODS: Forty consecutive patients (25 men and 15 women; mean [SD] age 64 [12] years) referred for staging of malignancy were prospectively included in this single-center, Institutional Review Board-approved study. Imaging using trimodality PET/CT-MR setup (full ring, time-of-flight PET/CT and 3-T whole-body MR imager) comprised PET, low-dose CT for anatomic referencing/attenuation correction of PET, and MR imaging with 3D dual-echo GRE pulse sequence, allowing the reconstruction of water-only (WO) and in-phase (IP) images. Two blinded and independent readers assessed all images randomly for the presence, the location, and the size of pulmonary nodules. Detection rates, defined as the proportion of screened participants with at least 1 pulmonary nodule, were compared between low-dose CT and MR imaging including both WO and IP images. RESULTS: Inter-reader agreements were high regarding the location (k = 0.93-0.98) and the size of pulmonary nodules (intraclass correlation analysis = 0.94-0.98) in CT and in MR imaging. Computed tomographic scans revealed 66 pulmonary nodules in 34 of the 40 patients (85%), whereas WO and IP images showed 56 and 58 pulmonary nodules in 33 of the 40 patients (83%), respectively. The detection rates of CT and MR imaging were similar (P's > 0.05) regarding all nodules, 18F-Fluordesoxyglucose-positive pulmonary nodules, and 18F-Fluordesoxyglucose-negative pulmonary nodules. The size of pulmonary nodules was significantly smaller on WO (P < 0.05; mean difference, 3 mm; 95% confidence interval, - 13 to 18 mm) and IP images (P < 0.001; mean difference, 4 mm; 95% confidence interval, -5 to 12 mm) compared with in CT. CONCLUSIONS: Our study indicates that a 3D Dixon-based, dual-echo GRE pulse sequence might be suitable for lung imaging in clinical whole-body PET/MR examinations. Although the detection rates were lower, there was no statistically significant difference on a patient-based evaluation concerning detection rates of pulmonary nodules compared with low-dose CT. Assessment of nodule location can be performed equally well with MR imaging.
    Investigative radiology 10/2012; · 4.85 Impact Factor
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    ABSTRACT: Tri-modality PET/CT-MRI includes the transfer of the patient on a dedicated shuttle from one system into the other. Advantages of this system include a true CT-based attenuation correction, reliable PET-quantification and higher flexibility in patient throughput on both systems. Comparative studies of PET/MRI versus PET/CT are readily accomplished without repeated PET with a different PET scanner at a different time point. Additionally, there is a higher imaging flexibility based on the availability of three imaging modalities, which can be combined for the characterization of the disease. The downside is a somewhat higher radiation dose of up to 3 mSv with a low dose CT based on the CT-component, longer acquisition times and potential misalignment between the imaging components. Overall, the tri-modality PET/CT-MR system offers comparative studies using the three different imaging modalities in the same patient virtually at the same time, and may help to develop reliable attenuation algorithms at the same time.
    MAGMA Magnetic Resonance Materials in Physics Biology and Medicine 10/2012; · 1.35 Impact Factor

Publication Stats

10k Citations
1,095.54 Total Impact Points

Institutions

  • 1989–2014
    • University of Zurich
      • • Center for Integrative Human Physiology
      • • Internal Medicine Unit
      Zürich, Zurich, Switzerland
  • 2008
    • Department of Nuclear Medicine
      Nyitra, Nitriansky, Slovakia
  • 2005
    • Schulthess Klinik, Zürich
      Zürich, Zurich, Switzerland
  • 2002
    • University of Wisconsin, Madison
      • Department of Medical Physics
      Madison, MS, United States
    • Universitätsspital Basel
      • Klinik für Allgemeinchirurgie
      Bâle, Basel-City, Switzerland
  • 1986–2002
    • University Hospital Zürich
      Zürich, Zurich, Switzerland
  • 1999
    • Universität Bern
      • Department of Geriatric Psychiatry
      Bern, BE, Switzerland
  • 1993
    • University of Cologne
      Köln, North Rhine-Westphalia, Germany
    • Psychiatrische Universitätsklinik Zürich
      Zürich, Zurich, Switzerland
  • 1990
    • Orthopädische Universitätsklinik Friedrichsheim
      Frankfurt, Hesse, Germany
  • 1987
    • ETH Zurich
      Zürich, Zurich, Switzerland