G K von Schulthess

University of Zurich, Zürich, Zurich, Switzerland

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Publications (334)1275.84 Total impact

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    ABSTRACT: Rationale: To compare the diagnostic accuracy of whole-body non-contrast-enhanced PET/MR with that of PET/CT in determining the stage of non-small-cell lung cancer. Methods: This study was approved by the institutional review board and by national government authorities. Forty-two consecutive patients referred for the initial staging of non-small-cell lung cancer underwent whole-body imaging with a sequential trimodality PET/CT-MR system. PET/MR and PET/CT datasets were evaluated separately, and a tumor-node-metastasis (TNM) stage was assigned based on the image analysis. Nodal stations in the chest were identified according to the mapping system of the American Thoracic Society. The standard of reference was histopathology for the tumor stage in 20 subjects, for the nodal stage in 22 patients and for extrathoracic metastases in 5 subjects. All other lesions were confirmed by at least one different imaging method. Wilcoxon signed-ranks test was used for comparing PET/MR with PET/CT. Results: PET/MR did not provide additional information compared with PET/CT. The diagnostic accuracy of both imaging modalities was equal (T staging: P = 0.177, N staging: P = 0.114, M staging: P = 0.465), however with advantages for PET/CT by trend. In the subgroup with histopathological confirmation of T stage and N stage, the situation was similar (T staging: P = 0.705, N staging: P = 0.334). Conclusion: This study indicates that PET/MR using a fast MR protocol does not improve the diagnostic accuracy of the staging of non-small-cell lung cancer.
    No preview · Article · Oct 2015 · Journal of Nuclear Medicine
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    ABSTRACT: Purpose: The aim of this study was to compare detection, lesion conspicuity and reader confidence of F-fluorodeoxyglucose (F-FDG)-PET/MR and F-FDG-PET/computed tomography (CT) in patients with F-FDG avid bone metastases. Materials and methods: In this prospective study, a total of 30 PET/CT and PET/MRI data sets were performed in 24 patients. Each examination was evaluated for the presence of PET-positive bone lesions consistent with metastatic involvement. Conspicuity of PET-positive bone lesions was evaluated on the corresponding PET/CT and PET/MR images and compared using the Wilcoxon signed-ranks test. Reader confidence was determined to evaluate whether PET/CT or PET/MR was more useful for the assessment of the bone metastases and was compared using Student's t-test. Results: Overall, in both examinations, PET/CT and PET/MRI detected 86 F-FDG-positive bone lesions. On all 30 PET/MRI examinations, at least one morphological correlate for F-FDG-positive bone lesions was found on the MR component (82 out of 86 lesions). PET/CT imaging allowed identification of corresponding structural changes on the CT component in 23 out of 30 studies (65 out of 86 lesions). In lesion-by-lesion analysis, the mean lesion conspicuity was significantly better on T1 fat MR imaging compared with CT imaging (P=0.005). In seven out of 30 studies, a significant increase in reader confidence of PET/MRI compared with PET/CT was found. Conclusion: PET/MRI offers higher reader confidence and improved conspicuity in bone metastases compared with PET/CT. However, the overall detection rate was not different. The highest possible clinical impact of PET/MRI appears to be in patients with limited, early bone metastatic disease.
    No preview · Article · Sep 2015 · Nuclear Medicine Communications
  • Felipe de Galiza Barbosa · Gustav von Schulthess · Patrick Veit-Haibach
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    ABSTRACT: The advent of simultaneous PET/MRI brought a large amount of possibilities in research and clinical applications into hybrid imaging. Unlike in PET/CT protocols, the MR component provides an almost unlimited number of pulse sequences and possibilities of different protocols in PET/MRI. Nevertheless, there is an imperative to reduce excessive imaging protocols to realistic clinical practice imaging acquisition. The design of a concise and indication-adapted protocol that provides an efficient workflow in a clinical reality is necessary to transform PET/MRI to a cost-effective imaging modality in addition to PET/CT. The aim of the current article is to point out the main considerations regarding workflow, imaging protocols, and image analysis in simultaneous PET/MRI system in oncology and share our thoughts and experience in acquisition optimization compared with the current literature. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Jul 2015 · Seminars in nuclear medicine
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    ABSTRACT: To evaluate the possible activity reduction in FDG-imaging in a Time-of-Flight (TOF) PET/MR, based on cross-evaluation of patient-based NECR (noise equivalent count rate) measurements in PET/CT, cross referencing with phantom-based NECR curves as well as initial evaluation of TOF-PET/MR with reduced activity. A total of 75 consecutive patients were evaluated in this study. PET/CT imaging was performed on a PET/CT (time-of-flight (TOF) Discovery D 690 PET/CT). Initial PET/MR imaging was performed on a newly available simultaneous TOF-PET/MR (Signa PET/MR). An optimal NECR for diagnostic purposes was defined in clinical patients (NECRP) in PET/CT. Subsequent optimal activity concentration at the acquisition time ([A]0) and target NECR (NECRT) were obtained. These data were used to predict the theoretical FDG activity requirement of the new TOF-PET/MR system. Twenty-five initial patients were acquired with (retrospectively reconstructed) different imaging times equivalent for different activities on the simultaneous PET/MR for the evaluation of clinically realistic FDG-activities. The obtained values for NECRP, [A]0 and NECRT were 114.6 (± 14.2) kcps (Kilocounts per second), 4.0 (± 0.7) kBq/mL and 45 kcps, respectively. Evaluating the NECRT together with the phantom curve of the TOF-PET/MR device, the theoretical optimal activity concentration was found to be approximately 1.3 kBq/mL, which represents 35% of the activity concentration required by the TOF-PET/CT. Initial evaluation on patients in the simultaneous TOF-PET/MR shows clinically realistic activities of 1.8 kBq/mL, which represent 44% of the required activity. The new TOF-PET/MR device requires significantly less activity to generate PET-images with good-to-excellent image quality, due to improvements in detector geometry and detector technologies. The theoretically achievable dose reduction accounts for up to 65% but cannot be fully translated into clinical routine based on the coils within the FOV and MR-sequences applied at the same time. The clinically realistic reduction in activity is slightly more than 50%. Further studies in a larger number of patients are needed to confirm our findings.
    Full-text · Article · Jul 2015 · PLoS ONE
  • Gustav von Schulthess · Gaspar Delso

    No preview · Chapter · Jun 2015
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    ABSTRACT: To compare the diagnostic accuracy of PET/MRI and PET/CT for staging and re-staging advanced gynaecological cancer patients as well as identify the potential benefits of each method in such a population. Twenty-six patients with suspicious or proven advanced gynaecological cancer (12 ovarian, seven cervical, one vulvar and four endometrial tumours, one uterine metastasis, and one primary peritoneal cancer) underwent whole-body imaging with a sequential trimodality PET/CT/MR system. Images were analysed regarding primary tumour detection and delineation, loco-regional lymph node staging, and abdominal/extra-abdominal distant metastasis detection (last only by PET/CT). Eighteen (69.2 %) patients underwent PET/MRI for primary staging and eight patients (30.8 %) for re-staging their gynaecological malignancies. For primary tumour delineation, PET/MRI accuracy was statistically superior to PET/CT (p < 0.001). Among the different types of cancer, PET/MRI presented better tumour delineation mainly for cervical (6/7) and endometrial (2/3) cancers. PET/MRI for local evaluation as well as PET/CT for extra-abdominal metastases had therapeutic consequences in three and one patients, respectively. PET/CT detected 12 extra-abdominal distant metastases in 26 patients. PET/MRI is superior to PET/CT for primary tumour delineation. No differences were found in detection of regional lymph node involvement and abdominal metastases detection. • PET/MRI is superior to PET/CT for primary tumour delineation • PET/CT represents a reliable tool to detect extra-abdominal distant metastasis • PET/MRI might be the preferred imaging modality for staging cervical and endometrial tumours • Whole-body staging for detection and evaluation of extra-abdominal metastases is mandatory.
    Full-text · Article · May 2015 · European Radiology
  • Gustav K von Schulthess · Patrick Veit-Haibach

    No preview · Article · May 2015 · Seminars in nuclear medicine

  • No preview · Conference Paper · May 2015
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    ABSTRACT: 18F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/ computed tomography (CT) imaging demands guidelines to safeguard sufficient image quality at low radiation exposure. Various FDG dose regimes have been investigated; however, body weight-adapted dose regimens and related image quality (IQ) have not yet been compared in the same patient. To investigate the relationship between FDG dosage and image quality in PET/CT in the same patient and determine prerequisites for low dosage scanning. This study included 61 patients undergoing a clinically indicated PET/CT imaging study and follow-up with a normal (NDS, 5 MBq/kg body weight [BW]) and low dosage scanning protocol (LDS, 4 MBq/kg BW), respectively, using a Discovery VCT64 scanner. Two blinded and independent readers randomly assessed IQ of PET using a 5-point Likert scale and signal-to-noise ratio (SNR) of the liver. Body mass index (BMI) was significantly lower at LDS (P = 0.021) and represented a significant predictor of SNR at both NDS (P < 0.001) and LDS (P = 0.005). NDS with a mean administered activity of 340 MBq resulted in significantly higher IQ (P < 0.001) and SNR as compared with LDS with a mean of 264 MBq (F-value = 23.5, P < 0.001, mixed model ANOVA adjusted for covariate BMI). Non-diagnostic IQ at LDS was associated with a BMI > 22 kg/m(2). FDG dosage significantly predicts IQ and SNR in PET/CT imaging as demonstrated in the same patient with optimal IQ achieved at 5 MBq/kg BM. PET/CT imaging at 4 MBq/kg BW may only be recommended in patients with a BMI ≤ 22 kg/m(2) to maintain diagnostic IQ.
    Preview · Article · Feb 2015
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    ABSTRACT: Background: The purpose of this study is to describe a clinical relation of noise equivalent count rate (NECR) - an objective measurement of positron emission tomography (PET) systems - measured in a large number of patients, to clinical image quality of PET and their relation to 18F-fluoro-2-deoxyglucose (FDG) activity and patient's weight. Methods: A total of 71 consecutive patients were evaluated in this retrospective study. All data was automatically analysed using Matlab to estimate the noise equivalent count rate. Then, image quality was evaluated according to two subjective scores: the IQ local score was a 3-point scale assigned to each bed position in all patients and the IQ global score was a 10-point scale assigned after evaluating the coronal whole-body PET. Patient data was also analysed concerning weight, body mass index, FDG dose at the start of acquisition (D Acq), presence of bowel uptake and presence of FDG-positive pathologic lesions. Two additional parameters were defined for each patient: the ratio between D Acq and patient weight (R DW) and the ratio between D Acq and patient BMI (R DBMI). Results: Clinically perceived image quality in PET has a significant positive correlation with NECR measured in patients, R DW, R DBMI and presence of pathologic lesions. Clinical image quality furthermore has significant negative correlation with weight, body mass index (BMI) and presence of bowel uptake. Thresholds of R DW and R DBMI in which clinical IQ is good to excellent in more than 90% of the patients were 2.6 and 8.0, respectively. Conclusions: Clinically perceived image quality in PET systems is positively and significantly related to NECR measured in patients. An optimal threshold for the R DW and R DBMI was defined in which clinical IQ is good to excellent in more than 90% of patients. With this data, it is possible to extrapolate technical as well as clinical image quality to other PET system and to predict clinical image perception.
    Full-text · Article · Dec 2014
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    ABSTRACT: 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. 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. 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 < 0.001 for both). The relative error for SUVmax was negligible for artifacts of 0.5-cm diameter (−0.1%), but substantial for artifacts of 5.2-cm diameter (−33%). 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.
    Full-text · Article · Dec 2014
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    Andrei Samarin · Felix P Kuhn · Fredrik Brandsberg · Gustav von Schulthess · Irene A Burger
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    ABSTRACT: Objective: 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. Materials and methods: In this prospective study, 43 patients underwent either sequential PET/CT and MR (n=31) or sequential SPECT and diagnostic CT (D-CT) (n=12). A side-loading patient shuttle system was used for patient transport. For PET/CT+MR, hardware-only coregistration was performed and then validated with anatomical landmarks on CT and MR. SPECT+D-CT image fusion was performed with external cobalt-57 markers and manual fusion. Registration accuracy was analysed by anatomical landmarks on the attenuation correction CT and the D-CT. Results: For the PET/CT+MR system, the mean offset between original CT and MR images in all 31 patients was 8.1±5.7 mm in the X-axis, 5±4 mm in the Y-axis and 4.9±5.6 mm in the Z-axis. The validation of the cobalt-57 marker-assisted SPECT+D-CT fusion yielded offsets of 0.7±1.7 mm in the X-axis, 2.1±1.7 mm in the Y-axis and 0.8±1.8 mm in the Z-axis. Conclusion: Sequential PET/CT+MR and SPECT+D-CT imaging using a dedicated patient shuttle system is feasible, resulting in mean offsets between data sets of 10.7 mm using the gantry laser system and 2.4 mm with fiducial markers.
    Preview · Article · Oct 2014 · Nuclear Medicine Communications
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    ABSTRACT: UNLABELLED: (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. METHODS: 18 patients with biopsy-proven NSCLC (n = 10) or HNSCC (n = 8) were included in this Institutional Review Board-approved, prospective multicenter study. All patients underwent (18)F-FDG PET/CT scans within 21 d before d-(18)F-FMT PET/CT. For all patients, safety and outcome data were assessed. RESULTS: No adverse reactions were observed related to d-(18)F-FMT. Fifty-two lesions were (18)F-FDG-positive, and 42 of those were malignant (34 histologically proven and 8 with clinical reference). Thirty-two of the 42 malignant lesions were also d-(18)F-FMT-positive, and 10 lesions had no tracer uptake above the level of the blood pool. Overall there were 34 true-positive, 8 true-negative, 10 false-negative, and only 2 false-positive lesions for d-(18)F-FMT, whereas (18)F-FDG was true-positive in 42 lesions, with 10 false-positive and only 2 false-negative, resulting in a lesion-based detection rate for d-(18)F-FMT and (18)F-FDG of 77% and 95%, respectively, with an accuracy of 78% for both tracers. A high d-(18)F-FMT tumor-to-blood pool ratio had a negative correlation with overall survival (P = 0.050), whereas the (18)F-FDG tumor-to-blood pool ratio did not correlate with overall survival. CONCLUSION: d-(18)F-FMT imaging in patients with NSCLC and HNSCC is safe and feasible. The presented preliminary results suggest a lower sensitivity but higher specificity for d-(18)F-FMT over (18)F-FDG, since there is no d-(18)F-FMT uptake in inflammation. This increased specificity may be particularly beneficial in areas with endemic granulomatous disease and may improve clinical management. Further clinical investigations are needed to determine its clinical value and relevance for the prediction of survival prognosis.
    Full-text · Article · Sep 2014 · Journal of Nuclear Medicine
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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.
    Full-text · Conference Paper · Sep 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.
    No preview · Conference Paper · Sep 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 short inversion time inversion-recovery ), Dixon-type liver accelerated volume acquisition ( LAVA liver accelerated volume acquisition ; GE Healthcare, Waukesha, Wis), and respiratory-gated periodically rotated overlapping parallel lines with enhanced reconstruction ( PROPELLER periodically rotated overlapping parallel lines with enhanced reconstruction ; 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 short inversion time inversion-recovery (3.08, P = .016) and LAVA liver accelerated volume acquisition (2.64, P = .002) images than on CT images (3.49), while findings with the PROPELLER periodically rotated overlapping parallel lines with enhanced reconstruction sequence (3.70, P = .436) were comparable to those at CT. In distant metastases, the PROPELLER periodically rotated overlapping parallel lines with enhanced reconstruction 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 short inversion time inversion-recovery , 3.32 [P = .014]; LAVA liver accelerated volume acquisition , 2.52 [P = .002]; PROPELLER periodically rotated overlapping parallel lines with enhanced reconstruction , 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.
    No preview · Article · Aug 2014 · Radiology
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    ABSTRACT: Objective 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. Methods Seventy patients with different head and neck cancers were enrolled in this prospective study. All patients underwent sequential contrast-enhanced (ce) PET/computed tomography (CT) and cePET/MRI using a tri-modality PET/CT-MR setup either for staging or re-staging. First, the DWI alone was evaluated, followed by the PET/MRI with conventional sequences, and in a third step, the PET/MRI with DWI was evaluated. McNemar’s test was used to evaluate differences in the accuracy of PET/MRI with and without DWI compared to the standard of reference. Results One hundred eighty-eight (188) lesions were found, and of those, 118 (62.8 %) were malignant and 70 (37.2 %) were benign. PET/MRI without DWI had a higher accuracy in detecting malignant lesions than DWI alone (86.8 % vs. 60.6 %, p
    Full-text · Article · Aug 2014 · European journal of nuclear medicine and molecular imaging
  • Gustav K von Schulthess

    No preview · Article · Aug 2014 · Journal of Magnetic Resonance Imaging
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    ABSTRACT: The goal of the present work was to compare the image quality obtained on a new ToF PET/MR prototype with that of equivalent state-of-the-art standalone systems. The MR image quality of this system was tested by scanning a volunteer with a comprehensive brain protocol. The same exact acquisition was repeated before and after the PET detectors were installed. Furthermore, a baseline measurement was acquired by importing the protocol on a GE Discovery 750 w MR system and repeating the acquisition on the same subject. The obtained datasets were registered and reviewed by medical doctors with experience in both radiology and nuclear imaging. Structure detectability, delineation and noise ratio were considered. MR image quality was shown to be virtually identical between the hybrid (pre- and post-insert) and standalone systems. We conclude that clinical MR sequences are not qualitatively affected by the presence of the PET detector insert.
    Full-text · Article · Jul 2014
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    Gaspar Delso · Tim Deller · Mehdi Khalighi · Patrick Veit-Haibach · Gustav von Schulthess

    Preview · Article · Jul 2014

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14k Citations
1,275.84 Total Impact Points

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Institutions

  • 1989-2015
    • University of Zurich
      • • Department of Biostatistics
      • • Internal Medicine Unit
      • • Center for Integrative Human Physiology
      Zürich, Zurich, Switzerland
  • 1986-2013
    • University Hospital Zürich
      Zürich, Zurich, Switzerland
  • 2005
    • Schulthess Klinik, Zürich
      Zürich, Zurich, Switzerland
  • 1987
    • ETH Zurich
      Zürich, Zurich, Switzerland
  • 1985
    • Kantonsspital St. Gallen
      San Gallo, Saint Gallen, Switzerland