Publications by authors named "Lars Stegger"

72 Publications

PET/CT Imaging and Physiology of Mice on High Protein Diet.

Int J Mol Sci 2021 Mar 22;22(6). Epub 2021 Mar 22.

Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands.

Background: High protein (HP) diets have been proposed to reduce body weight in humans. The diets are known to alter energy metabolism, which can affect the quality of [F]FDG PET heart images. In this preclinical study, we therefore explore the impact of a prolonged HP diet on myocardial [F]FDG uptake.

Methods: C57BL/6J (Black six (Bl6)) and apolipoprotein E-deficient () mice were fed chow, a HP diet, or a low protein (LP) diet for 12 weeks. At baseline and after treatment, the animals were injected with 33.0 MBq of [F]FDG and a 30 min PET/CT scan was made. Myocardial volume and [F]FDG uptake were quantified using PET and the % of body fat was calculated from CT.

Results: Myocardial [F]FDG uptake was similar for all diets at the follow-up scan but an increase between baseline and follow-up scans was noticed in the LP groups. Myocardial volume was significantly smaller in the C57BL HP group compared to the other Bl6 groups. Body weight increased less in the two HP groups compared to the chow and LP groups. Body fat percentage was significantly higher in the LP groups. This effect was stronger in C57BL mice (28.7%) compared to mice (15.1%).

Conclusions: Myocardial uptake of [F]FDG in mice is not affected by increased protein intake but [F]FDG uptake increases when the amount of protein is lowered. A lower body weight and percentage of body fat were noticed when applying a HP diet.
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http://dx.doi.org/10.3390/ijms22063236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8004865PMC
March 2021

Diagnostic efficiency of hybrid imaging using PSMA ligands, PET/CT, PET/MRI and MRI in identifying malignant prostate lesions.

Ann Nucl Med 2021 Mar 19. Epub 2021 Mar 19.

Department of Nuclear Medicine, University Hospital of Muenster, Muenster, Germany.

Objective: The objective of this study was to assess the accuracy of Ga-PSMA-11 PET/MRI, F-PSMA-1007 PET/CT, Ga-PSMA-11 PET/CT, and multiparametric (mp)MRI for the delineating of dominant intraprostatic lesions (IPL).

Materials And Methods: 35 patients with organ-confined prostate cancer who were assigned to definitive radiotherapy (RT) were divided into three groups based on imaging techniques: Ga-PSMA-PET/MRI (n = 9), F-PSMA-PET/CT (n = 16) and Ga-PSMA-PET/CT (n = 10). All patients without PSMA-PET/MRI received an additional mpMRI. PSMA-PET-based automatic isocontours and manual contours of the dominant IPLs were generated for each modality. The biopsy results were then used to validate whether any of the prostate biopsies were positive in the marked lesion using Dice similarity coefficient (DSC), Youden index (YI), sensitivity and specificity. Factors that can predict the accuracy of IPLs contouring were analysed.

Results: Diagnostic performance was significantly superior both for manual and automatic IPLs contouring using Ga-PSMA-PET/MRI (DSC/YI SUV-0.62/0.51), F-PSMA-PET/CT (DSC/YI SUV-0.67/0.53) or Ga-PSMA-PET/CT (DSC/YI SUV-0.63/0.51) compared to mpMRI (DSC/YI-0.47/0.41; p < 0.001). The accuracy for delineating IPLs was not improved by combination of PET/CT and mpMRI images compared to PET/CT alone. Significantly superior diagnostic accuracy was found for large prostate lesions (at least 15% from the prostate volume) and higher Gleason score (at least 7b) comparing to smaller lesions with lower GS.

Conclusion: IPL localization was significantly improved when using PSMA-imaging procedures compared to mpMRI. No significant difference for delineating IPLs was found between hybrid method PSMA-PET/MRI and PSMA-PET/CT. PSMA-based imaging technique should be considered for the diagnostics of IPLs and focal treatment modality.
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http://dx.doi.org/10.1007/s12149-021-01606-7DOI Listing
March 2021

Pain in survivors of Ewing sarcoma: Prevalence, associated factors and prediction of recurrence.

Pediatr Blood Cancer 2021 Mar 12;68(3):e28801. Epub 2020 Nov 12.

Department of Paediatric Haematology and Oncology, University Hospital Münster, Münster, Germany.

Background: While the prognosis of patients with Ewing sarcoma (EwS) is improving, little is known about the frequency of pain and its risk factors in survivors of EwS. This study aims to analyse the prevalence and risk factors of pain and its predictive value for recurrence.

Patients And Methods: In patients with remission after treatment of EwS, frequency and characteristics of pain within the first 5 years of follow up were assessed retrospectively.

Results: Of 80 patients, 37 (46%) presented with at least one episode of pain. Chronic pain (>3 months) was observed in 10 patients (13%). Experience of at least one episode of pain was associated with prior combined local treatment (surgery and radiation compared to surgery alone; odds ratio [OR] 5.83, 95% confidence interval [CI] 1.43-34.9, P = .007). A total of 59 episodes of pain were observed, including 47 acute and 12 chronic episodes. Lower limb pain accounted for 46% (27/59) of all episodes of pain, and was associated with primary tumour of the pelvis or lower extremity (OR 4.29, 95% CI 1.18-18.21, P = .025), which represented 64% (51/80) of all EwS. The positive predictive value of pain for recurrence was only 12%.

Conclusion: Pain is a common problem in survivors of EwS, which mostly affects the lower extremity, and should be regularly assessed. Interventions to reduce pain may be particularly important in patients with combined local treatment with surgery and radiation, who seem to be at considerably increased risk for pain. Patients presenting with pain should be examined for recurrence.
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http://dx.doi.org/10.1002/pbc.28801DOI Listing
March 2021

Analysis of failed therapy evaluations in radioembolization of primary and secondary liver cancers.

J Cancer Res Clin Oncol 2021 May 6;147(5):1537-1545. Epub 2020 Nov 6.

Institute of Clinical Radiology, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149, Munster, Germany.

Purpose: To analyze patients' characteristics and reasons for not performing planned transarterial radioembolization (TARE) in liver cancer after Tc-labeled macroaggregated albumin (Tc-MAA) evaluation.

Methods: In this retrospective single-center cohort, all patients undergoing Tc-MAA evaluation prior to planned TARE for primary or secondary liver cancer between 2009 and 2018 were analyzed. Patients were assigned to either "TARE" or "no TARE" group. Patients' characteristics, arising reasons for not performing the planned TARE treatment as well as predictive factors for occurrence of these causes were analyzed.

Results: 436 patients [male = 248, female = 188, median age 62 (23-88) years] with Tc-MAA evaluation prior to planned TARE of primary or secondary liver cancer were included in this study. 148 patients (33.9%) did not receive planned TARE. Patients with a hepatic tumor burden > 50%, no liver cirrhosis, no previous therapies and a higher bilirubin were significantly more frequent in "no TARE" compared to "TARE" group. Main reasons for not performing TARE were extrahepatic tracer accumulation (n = 70, 40.5%), non-target accumulation of Tc-MAA (n = 27, 15.6%) or a hepatopulmonary shunt fraction of more than 20% (n = 23, 13.3%). Independent preprocedural parameters for not performing planned TARE were elevated bilirubin (p = 0.021) and creatinine (p = 0.018) and lower MELD score (p = 0.031).

Conclusion: A substantial number of patients are precluded from TARE following Tc-MAA evaluation, which is, therefore, implicitly needed to determine contraindications to TARE and should not be refrained from in pretreatment process. However, a preceding careful patient selection is needed especially in patients with high hepatic tumor burden and alteration in lab parameters.
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http://dx.doi.org/10.1007/s00432-020-03443-zDOI Listing
May 2021

Repeated radioembolization in advanced liver cancer.

Ann Transl Med 2020 Sep;8(17):1055

Institute of Clinical Radiology, University Hospital Muenster, Muenster, Germany.

Background: To evaluate safety and clinical outcome of repeated transarterial Y (yttrium) radioembolization (TARE) in primary and metastatic liver cancer.

Methods: Between 2009 and 2018, n=288 patients underwent TARE for treatment of malignant liver disease in a tertiary care hospital. This retrospective single center study analyzed the safety and outcome of patients (n=11/288) undergoing repeated resin microsphere TARE. Included patients suffered from hepatocellular carcinoma (n=3), colorectal cancer (n=2), breast cancer (n=2), intrahepatic cholangiocarcinoma (n=3), and neuroendocrine carcinoma (n=1). All patients had shown either partial response (n=9) or stable disease (n=2) after first TARE. Lab parameters, response assessed by the Response Evaluation Criteria in Solid Tumors (mRECIST/RECIST) at 3 months and overall survival was analyzed. Additionally, patients with repeated TARE were compared to a matched control group (n=56) with single TARE therapy. Kaplan Meier analysis was performed to analyze survival.

Results: Patients after repeated TARE showed similar increase in lab parameters as compared to their first TARE. No case of radioembolization induced liver disease was observed. While n=5/11 patients showed a partial response and n=4/11 patients a stable disease after repeated TARE, only n=2/11 patients suffered from progressive disease. Median overall survival was 20.9±11.9 months for the repeated TARE group while it was 5.9±16.2 months for the control group.

Conclusions: Repeated Y TARE is safe and can be of benefit for patients yielding a comparable degree of local disease control compared to patients with singular TARE.
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http://dx.doi.org/10.21037/atm-20-2658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575953PMC
September 2020

EFFICACY OF 90Y-RADIOEMBOLIZATION IN METASTATIC COLORECTAL CANCER DEPENDING ON THE PRIMARY TUMOR SIDE.

Dig Dis 2020 Nov 3. Epub 2020 Nov 3.

Metastatic colorectal cancer (mCRC) is associated with different molecular biology, clinical characteristics and outcome depending on the primary tumor localization. We aimed to evaluate the effectiveness of 90Y-radioembolization (RE) for therapy of colorectal liver metastases depending on the primary tumor side. We performed a retrospective analysis of n=73 patients with mCRC and RE in our university liver center between 2009 and 2018. Patients were stratified according to the primary tumor side (left vs. right hemicolon), treatment response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST) at follow-up after 3 months. Kaplan-Meier analysis was performed to analyze survival followed by Cox regression to determine independent prognostic factors for survival. Prior to RE all patients had received systemic therapy, with either stable or progressive disease, but no partial or complete response. In n=22/73 (30.1%) patients the primary tumor side was in the right colon, in n=51/73 (69.9%) patients in the left colon. Hepatic tumor burden was ≤25% in n=36/73 (49.3%) patients and >25% in n=37/73 (50.7%) patients. At 3 months, n=21 (33.8%) patients showed treatment response [n=2 (3.2%) complete response, n=19 (30.6%) partial response], n=13 (21.0%) stable disease, and n=28 (45.2%) progressive disease after RE. The median survival in case of primary tumor side in the left colon was significantly higher than for primary tumors in the right colon (8.7 vs. 6.0 months, p=0.033). The median survival for a hepatic tumor burden ≤25% was significantly higher compared with >25% (13.9 vs. 4.3 months, p<0.001). The median overall survival was 6.1 months. The median survival after RE in hepatic-metastatic CRC depends on the primary tumor side and the pre-procedural hepatic tumor burden.
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http://dx.doi.org/10.1159/000512744DOI Listing
November 2020

Somatostatin Receptor-Targeted Radioligand Therapy in Head and Neck Paraganglioma.

World Neurosurg 2020 Nov 31;143:e391-e399. Epub 2020 Jul 31.

Department of Nuclear Medicine, University Hospital Münster, Münster, Germany.

Objective: Surgical resection is the therapy of choice in head and neck paraganglioma but is associated with considerable morbidity. For treatment of inoperable or progressive disease, less aggressive adjuvant options are warranted. This study assessed effectiveness and safety of peptide receptor radionuclide therapy (PRRT) with lutetium-177-DOTATATE for head and neck paraganglioma with emphasis on response assessment.

Methods: A retrospective analysis of 7 patients with head and neck paraganglioma treated with PPRT between May 2014 and October 2016 was performed. Three patients had jugulotympanic paraganglioma, 3 patients had carotid body tumors, and 1 patient had a combination of both. Patients underwent PRRT after discussion in the local tumor board regarding progressive disease, inoperability, or lack of other adjuvant options. All patients underwent 3-5 cycles of PRRT. Treatment response was evaluated by gallium-68-DOTATATE positron emission tomography/computed tomography and contrast-enhanced computed tomography or magnetic resonance imaging. Outcome measures were two-dimensional tumor diameters and total tumor volumes.

Results: Median patient age was 60 years (interquartile range: 14-84 years). All patients had stable disease at posttherapy assessment. Decreasing tumor volumes were found in 4 patients. Clinical symptoms improved in 2 patients. No progression or adverse events occurred during a median follow-up of 39 months (interquartile range: 35-47 months).

Conclusions: Somatostatin receptor-targeted therapy using lutetium-177-DOTATATE shows promising effectiveness with a high safety profile. Patients in whom surgical morbidity outweighs oncologic benefit should be informed about PRRT as a treatment option.
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http://dx.doi.org/10.1016/j.wneu.2020.07.165DOI Listing
November 2020

Response assessment of somatostatin receptor targeted radioligand therapies for progressive intracranial meningioma.

Nuklearmedizin 2020 Sep 20;59(5):348-355. Epub 2020 Jul 20.

Department of Nuclear Medicine, University Hospital Münster, Germany.

Background:  In somatostatin receptor (SSTR) expressing progressive meningioma, peptide receptor radionuclide therapy (PRRT) has shown effect in small clinical series. However, standardized treatment and response assessment protocols are lacking. We present our experience on PPRT with Lu-DOTATATE in progressive meningioma with a special emphasis on state-of-the-art response assessment.

Methods:  Retrospective analysis on PRRT with Lu-DOTATATE from 2015 to 2019. Pre- and post-therapy imaging was performed using MRI and Ga-DOTATATE-PET for standard bidimensional and volumetric analyses, respectively, following novel RANO guidelines.

Results:  Seven patients with progressive intracranial meningioma (median age 73 years, interquartile range 60-76; 5 WHO II, 2 WHO I; 5 multifocal) received a median of 4 cycles 2 3 4 of PRRT with Lu-DOTATATE in eight-week intervals. Three patients did not undergo post-therapy Ga-DOTATATE-PET due to early symptomatic progression and subsequent cessation of PRRT. After completion of 4 PRRT cycles volumetric PET imaging showed stable disease in two of four patients. According to bidimensional MRI response assessment, only one patient was stable. Progression free survival at six months was 42.9 %.

Conclusion:  In this heterogeneous collective of seven patients with progressive meningioma, 177Lu-DOTATATE therapies showed heterogeneous effectiveness. PET-based volumetric assessment should be used for response assessment in PRRT additionally to bidimensional imaging.
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http://dx.doi.org/10.1055/a-1200-0989DOI Listing
September 2020

Clinical Evaluation of a Data-Driven Respiratory Gating Algorithm for Whole-Body PET with Continuous Bed Motion.

J Nucl Med 2020 10 14;61(10):1520-1527. Epub 2020 Feb 14.

Department of Nuclear Medicine, University Hospital Münster, Münster, Germany.

Respiratory gating is the standard to prevent respiration effects from degrading image quality in PET. Data-driven gating (DDG) using signals derived from PET raw data is a promising alternative to gating approaches requiring additional hardware (e.g., pressure-sensitive belt gating [BG]). However, continuous-bed-motion (CBM) scans require dedicated DDG approaches for axially extended PET, compared with DDG for conventional step-and-shoot scans. In this study, a CBM-capable DDG algorithm was investigated in a clinical cohort and compared with BG using optimally gated (OG) and fully motion-corrected (elastic motion correction [EMOCO]) reconstructions. Fifty-six patients with suspected malignancies in the thorax or abdomen underwent whole-body F-FDG CBM PET/CT using DDG and BG. Correlation analyses were performed on both gating signals. Besides static reconstructions, OG and EMOCO reconstructions were used for BG and DDG. The metabolic volume, SUV, and SUV of lesions were compared among the reconstructions. Additionally, the quality of lesion delineation in the different PET reconstructions was independently evaluated by 3 experts. The global correlation coefficient between BG and DDG signals was 0.48 ± 0.11, peaking at 0.89 ± 0.07 when scanning the kidney and liver region. In total, 196 lesions were analyzed. SUV measurements were significantly higher in BG-OG, DDG-OG, BG-EMOCO, and DDG-EMOCO than in static images ( < 0.001; median SUV: static, 14.3 ± 13.4; BG-EMOCO, 19.8 ± 15.7; DDG-EMOCO, 20.5 ± 15.6; BG-OG, 19.6 ± 17.1; and DDG-OG, 18.9 ± 16.6). No significant differences between BG-OG and DDG-OG or between BG-EMOCO and DDG-EMOCO were found. Visual lesion delineation was significantly better in BG-EMOCO and DDG-EMOCO than in static reconstructions ( < 0.001); no significant difference was found when comparing BG and DDG for either EMOCO or OG reconstruction. DDG-based motion compensation of CBM PET acquisitions outperforms static reconstructions, delivering qualities comparable to BG approaches. The new algorithm may be a valuable alternative for CBM PET systems.
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http://dx.doi.org/10.2967/jnumed.119.235770DOI Listing
October 2020

Prognostic Factors for Overall Survival in Advanced Intrahepatic Cholangiocarcinoma Treated with Yttrium-90 Radioembolization.

J Clin Med 2019 Dec 25;9(1). Epub 2019 Dec 25.

Department of Clinical Radiology, Universitätsklinikum Münster, D-48149 Münster, Germany.

Purpose: To evaluate factors associated with survival following transarterial Y (yttrium) radioembolization (TARE) in patients with advanced intrahepatic cholangiocarcinoma (ICC).

Methods: This retrospective multicenter study analyzed the outcome of three tertiary care cancer centers in patients with advanced ICC following resin microsphere TARE. Patients were included either after failed previous anticancer therapy, including relapse after surgical resection, or for having a minimum of 25% of total liver volume affected by ICC. Patients were stratified and response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST) criteria at 3 months. Kaplan-Meier analysis was performed to analyze survival followed by cox regression to determine independent prognostic factors for survival.

Results: 46 patients were included (19 male, 27 female), median age 62.5 years (range 29-88 years). A total of 65% of patients had undergone previous therapy, while 63% had a tumor volume > 25% of the entire liver volume. Median survival was 9.5 months (95% CI: 6.1-12.9 months). Due to loss in follow-up, = 37 patients were included in the survival analysis. Cox regression revealed the extent of liver disease to one or both liver lobes being associated with survival, irrespective of tumor volume ( = 0.041). Patients with previous surgical resection of ICC had significantly decreased survival (3.9 vs. 12.8 months, = 0.002). No case of radiation-induced liver disease was observed.

Discussion: Survival after Y TARE in patients with advanced ICC primarily depends on disease extent. Only limited prognostic factors are associated with a general poor overall survival.
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http://dx.doi.org/10.3390/jcm9010056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7020033PMC
December 2019

Additional Local Therapy for Liver Metastases in Patients with Metastatic Castration-Resistant Prostate Cancer Receiving Systemic PSMA-Targeted Therapy.

J Nucl Med 2020 05 10;61(5):723-728. Epub 2019 Oct 10.

Department of Nuclear Medicine, University Hospital Münster, Münster, Germany

The aim of this study was to evaluate the efficacy of Lu-prostate-specific membrane antigen (PSMA)-617 (Lu-PSMA) and selective internal radiation therapy (SIRT) for the treatment of liver metastases of castration-resistant prostate cancer. Safety and survival of patients with metastatic castration-resistant prostate cancer and liver metastases assigned to Lu-PSMA alone ( = 31) or in combination with SIRT ( = 5) were retrospectively analyzed. Additionally, a subgroup ( = 10) was analyzed using morphologic and molecular response criteria. Median estimated survival was 5.7 mo for Lu-PSMA alone and 8.4 mo for combined sequential Lu-PSMA and SIRT. Lu-PSMA achieved discordant therapy responses with both regressive and progressive liver metastases in the same patient (best vs. worst responding metastases per patient: -35% vs. +63% diameter change; < 0.05). SIRT was superior to Lu-PSMA for the treatment of liver metastases (0% vs. 56% progression). The combination of Lu-PSMA and SIRT is efficient and feasible for the treatment of advanced prostate cancer. Lu-PSMA alone seems to have limited response rates in the treatment of liver metastases.
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http://dx.doi.org/10.2967/jnumed.119.233429DOI Listing
May 2020

A Cardiac Metastasis of Follicular Thyroid Carcinoma With Partly Squamous Cell Differentiation: Detection in FDG-PET Preceded Visibility on Echocardiography and MRI by More Than a Year.

Clin Nucl Med 2018 Dec;43(12):e473-e474

From the Departments of Nuclear Medicine.

PET using the radiotracer F-fluorodeoxyglucose (FDG) was performed in a patient who presented with elevated thyroglobulin (Tg) levels several years after initial therapy of follicular thyroid carcinoma (oncocytic variant) and in whom high-dose radioiodine (I) failed to locate recurrent tumor or to decrease Tg levels. A focal fluorodeoxyglucose uptake in the apical septum of the heart did not have a discernible correlate in echocardiography or MRI for more than 12 months. Finally, a metastasis of the follicular thyroid carcinoma with partly squamous cell differentiation was confirmed and treated by resection and stereotactic body radiotherapy.
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http://dx.doi.org/10.1097/RLU.0000000000002297DOI Listing
December 2018

177Lu-DOTATATE Therapy in Radioiodine-refractory Differentiated Thyroid Cancer: A Single Center Experience.

Clin Nucl Med 2018 Oct;43(10):e346-e351

Introduction: Patients with radioiodine-refractory differentiated thyroid cancer (RrDTC) have a rather poor prognosis and are in need of novel treatments. As RrDTCs can in some cases express somatostatin receptors (SSRT), targeting of these receptors by Ga/Lu-DOTATATE could evolve as a novel theranostic option.

Methods: Five RrDTC patients with limited further therapeutic options and documented expression of SSRT using Ga-DOTATATE-PET/CT received 2 to 4 cycles of PRRT with Lu-DOTATATE. Response to therapy was assessed by thyroglobulin (Tg) and morphological and metabolic criteria based on interim and follow-up Ga-DOTATATE-PET/CTs. Analysis was performed on a per-patient basis.

Results: In the post-therapy evaluation, only one out of five patients showed a partial response, whereas three patients had a progressive disease. One patient had discordant findings between stable imaging results albeit rising Tg levels.

Conclusion: In this case study of five patients, Lu-DOTATATE therapy showed only heterogeneous response and efficacy in RrDTC patients despite good lesional uptake in pre-therapeutic PET.
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http://dx.doi.org/10.1097/RLU.0000000000002219DOI Listing
October 2018

Data-driven gating in PET: Influence of respiratory signal noise on motion resolution.

Med Phys 2018 Jul 8;45(7):3205-3213. Epub 2018 Jun 8.

Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, Münster, 48149, Germany.

Purpose: Data-driven gating (DDG) approaches for positron emission tomography (PET) are interesting alternatives to conventional hardware-based gating methods. In DDG, the measured PET data themselves are utilized to calculate a respiratory signal, that is, subsequently used for gating purposes. The success of gating is then highly dependent on the statistical quality of the PET data. In this study, we investigate how this quality determines signal noise and thus motion resolution in clinical PET scans using a center-of-mass-based (COM) DDG approach, specifically with regard to motion management of target structures in future radiotherapy planning applications.

Methods: PET list mode datasets acquired in one bed position of 19 different radiotherapy patients undergoing pretreatment [ F]FDG PET/CT or [ F]FDG PET/MRI were included into this retrospective study. All scans were performed over a region with organs (myocardium, kidneys) or tumor lesions of high tracer uptake and under free breathing. Aside from the original list mode data, datasets with progressively decreasing PET statistics were generated. From these, COM DDG signals were derived for subsequent amplitude-based gating of the original list mode file. The apparent respiratory shift d from end-expiration to end-inspiration was determined from the gated images and expressed as a function of signal-to-noise ratio SNR of the determined gating signals. This relation was tested against additional 25 [ F]FDG PET/MRI list mode datasets where high-precision MR navigator-like respiratory signals were available as reference signal for respiratory gating of PET data, and data from a dedicated thorax phantom scan.

Results: All original 19 high-quality list mode datasets demonstrated the same behavior in terms of motion resolution when reducing the amount of list mode events for DDG signal generation. Ratios and directions of respiratory shifts between end-respiratory gates and the respective nongated image were constant over all statistic levels. Motion resolution d/d could be modeled as d/dmax=1-e-1.52(SNR-1)0.52, with d as the actual respiratory shift. Determining d from d and SNR in the 25 test datasets and the phantom scan demonstrated no significant differences to the MR navigator-derived shift values and the predefined shift, respectively.

Conclusions: The SNR can serve as a general metric to assess the success of COM-based DDG, even in different scanners and patients. The derived formula for motion resolution can be used to estimate the actual motion extent reasonably well in cases of limited PET raw data statistics. This may be of interest for individualized radiotherapy treatment planning procedures of target structures subjected to respiratory motion.
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http://dx.doi.org/10.1002/mp.12987DOI Listing
July 2018

Prostate-Specific Membrane Antigen-Negative Metastases-A Potential Pitfall in Prostate-Specific Membrane Antigen PET.

Clin Nucl Med 2018 Jun;43(6):e186-e188

Ga-PSMA-11 PET/CT was performed in a 74-year-old man because of biochemical recurrence of prostate cancer following radiation therapy of the prostate gland 24 months earlier. Besides focal nuclide accumulation in the prostate gland suggestive of local recurrence, PET scan revealed no further pathologic uptake. However, CT showed multiple pulmonic nodules suggestive of metastases. Thoracotomy and pathologic examination revealed the nodules to be prostate cancer metastasis. Furthermore, immunohistochemical staining with PSMA antibodies demonstrated a virtual lack of PSMA expression. This case demonstrates the possibility of PSMA-negative metastases of prostate cancer an important pitfall that should be known to physicians interpreting PSMA PET.
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http://dx.doi.org/10.1097/RLU.0000000000002073DOI Listing
June 2018

F-PSMA-1007 PET/CT at 60 and 120 minutes in patients with prostate cancer: biodistribution, tumour detection and activity kinetics.

Eur J Nucl Med Mol Imaging 2018 07 14;45(8):1329-1334. Epub 2018 Mar 14.

Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany.

Purpose: PSMA-targeted PET in patients with prostate cancer (PCa) has a significant impact on treatment decisions. By far the most frequently used PSMA ligand is Ga-labelled PSMA-11. However, due to the availability of larger amounts of activity, F-labelled PSMA ligands are of major interest. The aim of the present study was to evaluate the biodistribution and performance of the novel F-labelled ligand PSMA-1007 at two different time points.

Methods: This retrospective analysis included 40 consecutive patients (mean age 68.7 ± 8.1 years) referred for PSMA PET/CT. F-PSMA-1007 PET/CT was performed for localization of biochemical relapse, primary staging or therapy follow-up. Circular regions of interest were placed on representative slices of the liver, spleen, kidney, abdominal aortic blood pool, bone marrow (fourth lumbar vertebral body), urinary bladder and gluteus muscle at 60 and 120 min after injection. In malignant lesions the maximum standardized uptake (SUV) was measured within volumes of interest at both time points. All SUVs at 60 min were compared with those at 120 min after injection.

Results: The activity in the blood pool, urinary bladder and gluteus muscle was very low and decreased significantly over time (P < 0.001). Uptake in the liver, spleen and kidney showed a significant increase over time and uptake in the bone marrow remained stable. Overall, 135 PCa lesions were detected at 60 min and 136 lesions at 120 min after injection. The median SUV increased significantly (P < 0.001) from 10.98 to 15.51 between 60 and 120 min.

Conclusion: PCa lesions show a significant increase in F-PSMA-1007 uptake at 120 min compared with 60 min after injection. In addition, accumulation of the tracer in the urinary bladder was very low leading to improved contrast of adjacent PCa lesions. Increasing accumulation in the liver may limit the sensitivity of the tracer in detecting liver metastases.
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http://dx.doi.org/10.1007/s00259-018-3989-0DOI Listing
July 2018

Recurrence of Ewing sarcoma: Is detection by imaging follow-up protocol associated with survival advantage?

Pediatr Blood Cancer 2018 07 26;65(7):e27011. Epub 2018 Feb 26.

University Hospital Muenster, Westphalian-Wilhelms University, Muenster, Germany.

Background: The Cooperative Ewing Sarcoma Study and the Late Effects Surveillance System of the Society for Paediatric Oncology and Haematology recommend a structured follow-up imaging protocol (FUIP) for patients with Ewing sarcoma (EwS) with decreasing frequency of imaging over the first 5 years. The present study aims to assess the effectiveness of the FUIP for EwS patients regarding survival after relapse.

Patients And Methods: A retrospective multicenter analysis on 160 eligible patients with EwS recurrence was performed. Potential survival differences following recurrence diagnosis between patients with protocol-detected and symptomatic relapse were investigated using the Kaplan-Meier method. Additional subgroup analyses were performed on the relapse type. Overall survival (OS) was calculated from diagnosis of relapse to last follow-up or death.

Results: In the multicenter analysis, recurrence was detected by FUIP in 77 of 160 patients (48%) and due to symptoms in 83 patients (52%). Regarding the entire study population, OS was significantly superior in patients with protocol-detected relapse compared to patients with symptomatic relapse (median, 2.4 vs. 1.2 years; P < 0.001). In the subgroup analyses, patients whose lung recurrences were detected by the FUIP experienced longer survival after recurrence than those whose recurrences were detected symptomatically (P = 0.023). In the 83 symptomatic patients, pain was the most prevalent symptom of relapse (72%).

Conclusion: FUIP may benefit survival in EwS relapse, especially in lung recurrence. Pain was the leading symptom of relapse.
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http://dx.doi.org/10.1002/pbc.27011DOI Listing
July 2018

Advantage of F-PSMA-1007 over Ga-PSMA-11 PET imaging for differentiation of local recurrence vs. urinary tracer excretion.

Eur J Nucl Med Mol Imaging 2018 06 14;45(6):1076-1077. Epub 2018 Feb 14.

Department of Urology, University Hospital Muenster, 48149, Münster, Germany.

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http://dx.doi.org/10.1007/s00259-018-3952-0DOI Listing
June 2018

Targeting PSMA by radioligands in non-prostate disease-current status and future perspectives.

Eur J Nucl Med Mol Imaging 2018 05 15;45(5):860-877. Epub 2018 Jan 15.

Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany.

Background: Prostate-specific membrane antigen (PSMA) is the up-and-coming target for molecular imaging of prostate cancer. Despite its name, non-prostate-related PSMA expression in physiologic tissue as well as in benign and malignant disease has been reported in various publications. Unlike in prostate cancer, PSMA expression is only rarely observed in non-prostate tumor cells. Instead, expression occurs in endothelial cells of tumor-associated neovasculature, although no endothelial expression is observed under physiologic conditions. The resulting potential for tumor staging in non-prostate malignant tumors has been demonstrated in first patient studies. This review summarizes the first clinical studies and deduces future perspectives in staging, molecular characterization, and PSMA-targeted radionuclide therapy based on histopathologic examinations of PSMA expression.

Conclusions: The non-exclusivity of PSMA in prostate cancer opens a window to utilize the spectrum of available radioactive PSMA ligands for imaging and molecular characterization and maybe even therapy of non-prostate disease.
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http://dx.doi.org/10.1007/s00259-017-3922-yDOI Listing
May 2018

Impact of presynaptic sympathetic imbalance in long-QT syndrome by positron emission tomography.

Heart 2018 02 1;104(4):332-339. Epub 2017 Sep 1.

Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany.

Objective: We investigated the impact of cardiac presynaptic norepinephrine recycling in patients with long-QT syndrome (LQTS) using positron emission tomography (PET) with C-meta-hydroxyephedrine ([C]mHED-PET).

Methods: [C]mHED-PET was performed in 25 patients with LQTS (LQT1: n=14; LQT2: n=11) and 20 healthy controls and correlated with clinical parameters. [C]mHED-PET images were analysed for global and regional retention indices (RI) and washout rates (WO) reflecting dynamic parameters of the tracer activity.

Results: Global and regional RI values were similar between patients with LQTS and controls. Although the global WO rates were similar between these groups, regional WO rates were on average higher in the lateral left ventricle (LV) wall in patients with LQTS (dose, mean ±SD; 0.08±0.14 vs 0.00%±0.09% min; p=0.033). In addition, patients with LQTS with a longer QTc interval showed a higher global WO rate. Clinical symptoms correlated with higher global WO rates. In the presence of normal global WO rates, asymptomatic LQTS patients showed higher global RI values.

Conclusion: The increased regional WO rate of [C]mHED in the lateral LV suggests an imbalance of presynaptic catecholamine reuptake and release, resulting in a higher synaptic catecholamine concentration, in particular in LQT1 patients. This might enhance β-adrenoceptor signalling and thereby aggravate inherited ion channel dysfunction and may facilitate occurrence of ventricular tachyarrhythmias. Detection of regional differences in LV sympathetic nervous function may modify disease expression and potentially serve as a non-invasive risk marker in congenital LQTS.

Trial Registration Number: 2006-002767-41;Results.
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http://dx.doi.org/10.1136/heartjnl-2017-311667DOI Listing
February 2018

Impact of PET acquisition durations on image quality and lesion detectability in whole-body Ga-PSMA PET-MRI.

EJNMMI Res 2017 Dec 6;7(1):12. Epub 2017 Feb 6.

Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany.

Background: While Ga-PSMA PET-MRI might be superior to PET-CT with regard to soft tissue assessment in prostate cancer evaluation, it is also known to potentially introduce additional PET image artefacts. Therefore, the impact of PET acquisition duration and attenuation data on artefact occurrence, lesion detectability, and quantification was investigated. To this end, whole-body PET list mode data from 12 patients with prostate cancer were acquired 1 h after injection of 2 MBq/kg [Ga]HBED-CC-PSMA on a hybrid PET-MRI system. List mode data were further transformed into data sets representing 300, 180, 90, and 30 s acquisition duration per bed position. Standard attenuation and scatter corrections were performed based on MRI-derived attenuation maps, complemented by emission-based attenuation data in areas not covered by MRI. A total of 288 image data sets were reconstructed with varying acquisition durations for emission and attenuation data with and without scatter and prompt gamma correction, and further analysed regarding image quality and diagnostic performance.

Results: Decreased PET acquisition durations resulted in a significantly increased incidence of halo artefacts around kidneys and bladder, decreased lesion detectability and lower SUV as well as markedly lower arm attenuation values: Halo artefacts were present in 5 out of 12 cases at 300-s duration, in 6 at 180 s, in 10 at 90 s, and in 11 cases at 30 s. Using attenuation data of the 300 s scans restored artefact occurrence to the original 300-s level. Prompt gamma correction only led to small improvements in terms of artefact occurrence and size. Of the 141 detected lesions in the 300-s images one lesion was not detected at 180 s, 28 at 90 s, and 64 at 30 s. Using the 300-s attenuation map decreased non-detectability of lesions to zero at 180 s, 9 at 90 s, and 52 at 30 s. Attenuation maps at 90 and 30 s demonstrated markedly lower mean arm attenuation values (0.002 cm) than those at 300 s (0.084 cm), and 180 s (0.062 cm).

Conclusions: Short acquisition durations of less than 3 minutes per bed position result in unacceptable image artefacts and decreased diagnostic performance in current whole-body Ga-PSMA PET-MRI and should be avoided. Increased image noise and imperfections in generated attenuation maps were identified as a paramount cause for image degradation.
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http://dx.doi.org/10.1186/s13550-017-0261-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5293699PMC
December 2017

Diagnostic value of additional Ga-PSMA-PET before Ra-dichloride therapy in patients with metastatic prostate carcinoma.

Nuklearmedizin 2017 Feb 11;56(1):14-22. Epub 2017 Jan 11.

Axel Bräuer, Department of Nuclear Medicine,, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany, Phone: +49 251 8347362, Fax: +49 251 8347363, E-Mail:

Purpose: Medical imaging plays an important role in selecting patients with metastatic castration-resistant prostate cancer for Ra-dichloride therapy of bone metastases. The purpose of this study was to investigate whether Ga-PSMA-PET has incremental value over conventional imaging for selecting patients suitable for Ra-dichloride therapy.

Methods: In 27 consecutive patients referred for Ra-dichloride therapy additional Ga-PSMA-PET/CT was performed and tracer distribution was evaluated systematically with respect to the detection of visceral metastases and bone metastases with inadequate uptake on bone scintigraphy.

Results: In 4 patients (15 %) Ga-PSMA-PET revealed previously unknown visceral metastases (3 liver, 1 adrenal gland), which changed the therapeutic decision in 2 cases. PET revealed more extended tumour involvement in the bone compared to bone scintigraphy in 9 patients (33 %). In 3 of these, the mismatch was extensive enough to question suitability for Ra-dichloride therapy.

Conclusions: Additional Ga-PSMA-PET as a gatekeeper between conventional staging and Ra-dichloride therapy can provide valuable additional information with regard to visceral metastases and tumour manifestations without adequate bone mineral turnover. It may lead to a change in therapeutic management in a significant number of patients and should therefore be considered in future clinical trials.
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http://dx.doi.org/10.3413/Nukmed-0846-16-09DOI Listing
February 2017

An artefact of PET attenuation correction caused by iron overload of the liver in clinical PET-MRI.

Eur J Hybrid Imaging 2017 8;1(1):10. Epub 2017 Nov 8.

1Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany.

Background: Attenuation correction is one of the most important steps in producing quantitative PET image data. In hybrid PET-MRI systems, this correction is far from trivial, as MRI data are not correlated to PET attenuation properties of the scanned object. Commercially available systems often employ correction schemes based on segmenting the body into different tissue classes (air, lung tissue, fat-, and water-like soft tissue), e.g. by using a dual time-point Dixon sequence. However, several pitfalls are known for this approach. Here a specific artefact of MR-based PET attenuation correction is reported, caused by misidentifying the liver as lung tissue due to iron overload.

Case Presentation: A patient with a history of hematopoietic stem cell transplantation underwent a whole-body [F]FDG PET-MRI scan. Markedly low liver uptake values were noted in the PET images, seemingly caused by an erroneous assignment of lung tissue attenuation values to the liver. A closer investigation demonstrated markedly low MRI intensity values of the liver, indicative of secondary hemochromatosis (iron overload) most probably due to a history of multiple blood transfusions. Manual assignment of adequate liver attenuation values resulted in more realistic PET images.

Conclusions: Iron overload of the liver was identified as a cause of a specific attenuation correction artefact. It remains to be seen how frequent this artefact will be encountered; however, this case highlights that attenuation maps should always be checked during PET image interpretation in hybrid PET-MRI.
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http://dx.doi.org/10.1186/s41824-017-0015-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5954667PMC
November 2017

Ewing sarcoma during follow-up.

Nuklearmedizin 2017 11;56(6):233-238. Epub 2018 Jan 11.

Aim: To evaluate the performance of a prospectively defined follow-up imaging protocol that includes FDG-PET(/CT) to detect tumour recurrence in Ewing sarcoma (EwS) before becoming symptomatic.

Methods: Imaging results and clinical data during follow-up were retrospectively analysed from all patients treated successfully within the EURO E.W.I.N.G. 99 trial at the University Hospital Münster, Germany. All patients received follow-up imaging according to a comprehensive protocol that included regular X-ray, CT, MRI, bone scan and PET(/CT), albeit not all on the same day and with varying intervals for the different modalities.

Results: 80 of 105 patients underwent follow-up at our institution after complete remission. 30 patients had recurrent tumour during the follow-up period of 3.6 years on average. 19 recurrences (63%) were detected by scheduled imaging before the advent of clinical symptoms. The majority of these recurrences (8 out of 19; 42%) was detected first by PET/ CT (and confirmed with additional imaging thereafter), even though the total number of PET/CTs was comparatively low (138) and PET/CT was not systematically scheduled before other imaging techniques. Recurrences detected by bone scan were also detectable by PET.

Conclusions: The implemented follow-up protocol was effective in the detection of EwS recurrence before the advent of symptoms. Most cases of those detected before onset of symptoms were detected by PET/CT first. This hybrid imaging modality should therefore be considered in the routine follow-up of EwS patients, as is standard in our hospital. In combination with PET, low-dose chest CT seems to be sufficient in the detection of small pulmonary nodules.
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http://dx.doi.org/10.3413/Nukmed-0909-17-07DOI Listing
November 2018

Cryopreservation of primary human monocytes does not negatively affect their functionality or their ability to be labelled with radionuclides: basis for molecular imaging and cell therapy.

EJNMMI Res 2016 Dec 24;6(1):77. Epub 2016 Oct 24.

Department of Cardiovascular Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, 48149, Münster, Germany.

Background: Circulating white blood cells crucially contribute to maintenance and repair of solid organs. Therefore, certain cell populations such as monocytes are attractive targets for use in molecular imaging and cell imaging, e.g. after labelling with radionuclides, as well as for cell therapies. However, the preparation of monocytes may require freezing and thawing to preserve cells for timely and standardised applications. Additional modifications of these cells such as radioisotope labelling are necessary prior to their application in vivo. We therefore tested the hypothesis whether cryopreservation of freshly isolated circulating human monocytes affects their functional phenotype or their suitability for radionuclide labelling.

Results: CD14+CD16- monocytes were isolated from human peripheral blood. They were either directly used for cellular assays and labelling or frozen down using cryoprotectants. In the latter case, cells were thawed prior to further use and analysed for survival, chemotactic responses to various growth factors and adhesion on endothelial cells. In addition, both fresh and cryopreserved monocytes were labelled with radiotracers followed by assessment of survival and chemotactic responses. In all functional assays performed, cryopreserved monocytes did not significantly differ from freshly isolated monocytes with regard to their functionality. Cryopreservation did not affect cell survival. There was no effect on the chemotactic response of monocytes towards different growth factors. Likewise, adhesion properties remained unchanged following cryopreservation. Moreover, the labelling efficiency was similar for freshly isolated and cryopreserved monocytes. Labelling did not negatively affect monocyte survival and function.

Conclusions: Our data indicate that cryopreservation of freshly isolated human primary monocytes is feasible and does not negatively affect their functionality when used for labelling and functional assessment.
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http://dx.doi.org/10.1186/s13550-016-0232-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5078113PMC
December 2016

Benefit of 68Ga-PSMA-PET/CT in Patients Considered for 223Ra-Dichloride Therapy.

Clin Nucl Med 2016 Dec;41(12):951-952

From the Departments of *Nuclear Medicine and †Urology, University Hospital Münster, Münster, Germany.

A 66-year-old man with castration-resistant prostate carcinoma and multiple symptomatic bone mestastases was considered for Ra-dichloride (Xofigo) therapy. Staging with Ga-PSMA-PET/CT revealed additional extensive tumor involvement of the spine without relevant uptake in bone scintigraphy. Based on this imaging result, the patient was rescheduled for a PSMA-targeted therapy. Additional Ga-PSMA-PET/CT may have a considerable benefit for patients considered for Xofigo.
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http://dx.doi.org/10.1097/RLU.0000000000001374DOI Listing
December 2016

Subacute Stroke Mimicking Cerebral Metastasis in 68Ga-PSMA-HBED-CC PET/CT.

Clin Nucl Med 2016 Oct;41(10):e449-51

From the *Department of Nuclear Medicine, University Hospital Münster, Münster, Germany; and †European Institute for Molecular Imaging, University of Münster, Münster, Germany.

A 65-year-old man with disseminated bone metastases of prostate cancer was referred for Ga-PSMA-HBED-CC-PET/CT (short PSMA-PET/CT) to exclude visceral metastases before treatment of bone metastases with Ra-dichloride. Apart from disseminated bone metastases, PSMA-PET/CT revealed a focal cerebral tracer uptake in the right frontal lobe highly suspicious for cerebral spread. According to patient history, a cerebral infarction occurred 14 days before PSMA imaging in corresponding localization confirmed by MRI scanning. This case demonstrates the possibility of false-positive finding of cerebral metastases in PSMA-PET early after stroke.
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http://dx.doi.org/10.1097/RLU.0000000000001291DOI Listing
October 2016

Radioligand Therapy With 177Lu-PSMA-617 as A Novel Therapeutic Option in Patients With Metastatic Castration Resistant Prostate Cancer.

Clin Nucl Med 2016 Jul;41(7):522-8

From the Departments of *Nuclear Medicine and †Urology, University Hospital Münster, Münster, Germany.

Background: Despite progress in treatment of metastatic castration-resistant prostate cancer (mCRPC), new approaches are urgently needed. Recently theranostic concepts using radiolabeled ligands of the prostate-specific membrane antigen (PSMA) have been developed for diagnostics and therapy of patients with advanced mCRPC. The aim of this study was to evaluate tumor response, adverse effects, and survival in patients undergoing radioligand therapy with Lu-PSMA-617.

Methods: Fifty therapies using Lu-PSMA-617 were performed in 28 consecutive patients with mCRPC and exhausted conventional therapeutic options (median age, 73.4 years; range, 45-87 years). Data were retrospectively analyzed with focus on response, safety, and survival. The median overall survival was compared with that of a recent historical patient cohort treated with best supportive care prior to availability of Lu-PSMA-617.

Results: Any PSA decline occurred in 59% and 75% of patients after 1 and 2 therapies. Moreover, a PSA decline of 50% or greater occurred in 32% and 50%. Therapies were well tolerated. Hematologic and renal parameters changed insignificantly; permanent xerostomia or other safety-related toxicity did not occur. The estimated median survival was 29.4 weeks, significantly longer than survival in the historical best supportive care group (19.7 weeks [hazard ratio, 0.44; 95% confidence interval, 0.20-0.95]; P = 0.031).

Conclusions: Results from 50 therapies show that radioligand therapy with Lu-PSMA-617 is effective and well tolerated and seems to increase overall survival. A future randomized controlled prospective study will be necessary to confirm these results.
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http://dx.doi.org/10.1097/RLU.0000000000001240DOI Listing
July 2016

[(68)Ga]DOTATATE PET/MRI and [(18)F]FDG PET/CT are complementary and superior to diffusion-weighted MR imaging for radioactive-iodine-refractory differentiated thyroid cancer.

Eur J Nucl Med Mol Imaging 2016 Sep 8;43(10):1765-72. Epub 2016 Apr 8.

Department of Nuclear Medicine, University Hospital Münster, Münster, Germany.

Purpose: The purpose of this study was to determine whether [(68)Ga]DOTATATE PET/MRI with diffusion-weighted imaging (DWI) can replace or complement [(18)F]FDG PET/CT in patients with radioactive-iodine (RAI)-refractory differentiated thyroid cancer (DTC).

Methods: The study population comprised 12 patients with elevated thyroglobulin and a negative RAI scan after thyroidectomy and RAI remnant ablation who underwent both [(18)F]FDG PET/CT and [(68)Ga]DOTATATE PET/MRI within 8 weeks of each other. The presence of recurrent cancer was evaluated on a per-patient, per-organ and per-lesion basis. Histology, and prior and follow-up examinations served as the standard of reference.

Results: Recurrent or metastatic tumour was confirmed in 11 of the 12 patients. [(68)Ga]DOTATATE PET(/MRI) correctly identified the tumour burden in all 11 patients, whereas in one patient local relapse was missed by [(18)F]FDG PET/CT. In the lesion-based analysis, overall lesion detection rates were 79/85 (93 %), 69/85 (81 %) and 27/82 (33 %) for [(18)F]FDG PET/CT, [(68)Ga]DOTATATE PET/MRI and DWI, respectively. [(18)F]FDG PET(/CT) was superior to [(68)Ga]DOTATATE PET(/MRI) in the overall evaluation and in the detection of pulmonary metastases. In the detection of extrapulmonary metastases, [(68)Ga]DOTATATE PET(/MRI) showed a higher sensitivity than [(18)F]FDG PET(/CT), at the cost of lower specificity. DWI achieved only poor sensitivity and was significantly inferior to [(18)F]FDG PET in the lesion-based evaluation in the detection of both extrapulmonary and pulmonary metastases.

Conclusion: [(18)F]FDG PET/CT was more sensitive than [(68)Ga]DOTATATE PET/MRI in the evaluation of RAI-refractory DTC, mostly because of its excellent ability to detect lung metastases. In the evaluation of extrapulmonary lesions, [(68)Ga]DOTATATE PET(/MRI) was more sensitive and [(18)F]FDG PET(/CT) more specific. Furthermore, DWI did not provide additional information and cannot replace [(18)F]FDG PET for postoperative monitoring of patients with suspected RAI-refractory DTC.
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http://dx.doi.org/10.1007/s00259-016-3378-5DOI Listing
September 2016

Impact of MR-safe headphones on PET attenuation in combined PET/MRI scans.

EJNMMI Res 2016 Dec 2;6(1):20. Epub 2016 Mar 2.

Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany.

Background: MR headphones are attenuation sources affecting PET quantification in hybrid PET/MRI. Despite potentially better patient communication, usage in PET/MRI scans is not approved by the vendor. This study aims to determine the impact of headphones on PET by means of phantom and patient scans. Additionally, the perceived benefit of using headphones was evaluated.

Findings: A cylinder phantom was scanned without and with dedicated MR headphones in a PET/CT scanner. Headphone attenuation was additionally assessed in a clinical setup in 10 patients on a PET/MR scanner using F-18-fluoro-deoxy-glucose. The difference in tracer uptake with and without headset was determined for the various brain regions. Additionally, the patients were asked for differences in noise levels, patient comfort, communication quality, and preference. CT data revealed headphone attenuation values of 350-500 HU. Neglecting headphone attenuation leads to a decrease in PET values between the earcups of about 11 % when compared to the correctly reconstructed data. Regions further away from the headphones were less affected. Patient images demonstrated a decrease of 11 % on average in the cerebellum and temporal lobes, while other regions were less affected. No visual artefacts in the images were noticed. On average, no advantage in terms of noise and patient comfort and only slightly better quality of communication were imparted by the patients.

Conclusions: Using headphones during PET/MR acquisition leads to a negative bias in brain uptake values without introducing obvious image artefacts. Since they lack benefits for the patients, they should be avoided if PET quantification of the brain is needed.
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http://dx.doi.org/10.1186/s13550-016-0178-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4775719PMC
December 2016