T. Poeppel - Academia.edu (original) (raw)
Papers by T. Poeppel
European Journal of Nuclear Medicine and Molecular Imaging, 2015
Annals of the Rheumatic Diseases, 2013
ABSTRACT Background PET is a nuclear imaging technique that depicts functional processes within t... more ABSTRACT Background PET is a nuclear imaging technique that depicts functional processes within the body by detecting pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), introduced into the body on a biologically active molecule. 3D images of tracer concentration are then constructed by computer analysis. The biologically active molecule used for PET is 18F labeled Fluoride (18F-F), a bone-seeking agent reflecting bone perfusion and remodeling. The concentrations of tracer image tissue metabolic activity, in terms of regional bone remodeling. PET scans are increasingly read alongside CT or MRI scans, with the combination (“co-registration”) giving both anatomic and metabolic information, e.g. what the structure is, and what it is doing biochemically. Objectives Based on our long experience with MRIs of patients with axSpA we have inaugurated a pilot study with simultaneous PET/MRI in order to examine whether the addition of the PET technique may provide different and additional information in comparison to MRI alone. Methods Eleven axSpA patients, median age 39 years, disease duration range 0.5-10 years, mean BASDAI 5.3, most of them fulfilling the NY criteria for AS, were examined by PET/3-Tesla MRI 40 minutes after injection of a mean dose of 157 MBq of 18F-F using a hybrid whole-body PET/MRI scanner (Siemens Biograph mMR®). 3T-MRIs were scored blinded to patient’s clinical characteristics by two readers (1 rheumatologist and 1 radiologist) using the Berlin MRI score and also by recording inflammatory lesions on a vertebral edge (VE) level. In a second step PET/MRIs were read blindly by the same readers also based on the VE involvement of individual vertebral bodies. Results Acquisition of whole-spine hybrid 18F-F PET/MRI scans was successful in all patients. The resulting mean effective radiation dose per patient was 3.76 mSv. Co-registration of PET/MRI fusion images was highly accurate and allowed a precise comparison of MRI and PET findings. The mean Berlin MRI score was 6.8 (range 0 – 31). In the direct comparison of the MRI and PET signal the two readers saw consistent signals in almost 90% of the sites studied. However, there were some areas where signals differed, for example within existing syndesmophytes where the PET signal was increased but conventional MRIs showed no signal of active inflammation, or the area of sternum and lateral or posterior spinal elements such as facet joints and spinous process. Conclusions The new technique of combining the PET and MRI provides largely similar imaging signals as conventional MRI. However, we did observe differences between the two techniques - especially in areas with less inflammatory activity where bone metabolism seemed to be active or in areas with blurred resolution on conventional MRI. More studies are needed to answer the question whether the differences between these techniques are pathogenically relevant, whether they can be reliably reproduced and quantified, and, of course, whether they are sensitive to change. Especially the possibility that PET detects osteoblastic activity in areas where no inflammatory signal is detected seems to be of interest. Disclosure of Interest None Declared
Annals of the Rheumatic Diseases
Background PET is a nuclear imaging technique that depicts functional processes within the body b... more Background PET is a nuclear imaging technique that depicts functional processes within the body by detecting pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), introduced into the body on a biologically active molecule. 3D images of tracer concentration are then constructed by computer analysis. The biologically active molecule used for PET is 18F labeled Fluoride (18F-F), a bone-seeking agent reflecting bone perfusion and remodeling. The concentrations of tracer image tissue metabolic activity, in terms of regional bone remodeling. PET scans are increasingly read alongside CT or MRI scans, with the combination (“co-registration”) giving both anatomic and metabolic information, e.g. what the structure is, and what it is doing biochemically. Objectives Based on our long experience with MRIs of patients with axSpA we have inaugurated a pilot study with simultaneous PET/MRI in order to examine whether the addition of the PET technique may provide diffe...
The quarterly journal of nuclear medicine and molecular imaging : official publication of the Italian Association of Nuclear Medicine (AIMN) [and] the International Association of Radiopharmacology (IAR), [and] Section of the Society of..., Jan 8, 2015
A retrospective study using PET/CT imaging with 124I--labeled metaiodobenzylguanidine (124I--MIBG... more A retrospective study using PET/CT imaging with 124I--labeled metaiodobenzylguanidine (124I--MIBG) was performed to estimate the (radiation) absorbed dose to the salivary glands in neuroendocrine cancer patients undergoing 131I--MIBG therapy and to compare these results with those in radioiodine (131I--iodide) therapy. Twenty--seven patients received individual 124I--MIBG--PET/CT dosimetries, among whom 18 had not previously undergone any MIBG therapies (patient group before treatment) and 9 had already received MIBG therapies prior to the tracer dosimetries (patient group after treatment). For each patient, three or four 124I--MIBG PET/CT scans were performed at approximately 4 and 24 h, as well as at approximately 48 or/and ≥96 h after tracer injection. The absorbed doses per administered 131I--MIBG activity to the submandibular and parotid glands were calculated based on the MIRD concept, with its assumption of an uniform glandular activity distribution. The mean±standard deviati...
![Research paper thumbnail of Combined PET imaging and diffusion-weighted imaging of intermediate and high-risk primary prostate carcinomas with simultaneous [18F] choline PET/MRI](https://attachments.academia-assets.com/48222233/thumbnails/1.jpg)
](PloS one, 2014
To characterize intermediate and high-risk prostate carcinomas with measurements of standardized ... more To characterize intermediate and high-risk prostate carcinomas with measurements of standardized uptake values (SUVs) and apparent diffusion coefficient (ADC) values by means of simultaneous [18F] choline PET/MRI. 35 patients with primary prostate cancer underwent simultaneous [18F] choline PET/MRI. From these, 21 patients with an intermediate and high risk constellation who were not under ongoing hormonal therapy were included. Altogether 32 tumor lesions with a focal uptake of [18F] choline could be identified. Average ADC values (ADCaver) minimum ADC values (ADCmin) as well as maximum and mean SUVs (SUVmax, SUVmean) of tumor lesions were assessed with volume-of-interest (VOI) and Region-of-interest (ROI) measurements. As a reference, also ADCaver, ADCmin and SUVmax and SUVmean of non-tumorous prostate tissue were measured. Statistical analysis comprised calculation of descriptive parameters and calculation of Pearson's product moment correlations between ADC values and SUVs o...
RöFo : Fortschritte auf dem Gebiete der Röntgenstrahlen und der Nuklearmedizin, 2010
To retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahe... more To retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahepatic shunting before SIRT. 30 patients (mean age: 64+/-12 years) with hypervascularized hepatic tumors underwent hepatic angiography, coil embolization of gastrointestinal collaterals and 99mTc-macroaggregated albumin (MAA) SPECT/CT before SIRT. Before MAA injection via a microcatheter from the intended treatment position, an angiography and angiography-based C-arm CT (XperCT, Philips Healthcare) were acquired. Angiographies and XperCT were performed from 48 microcatheter positions followed by MAA injections and MAA-SPECT/CT. MAA-SPECT/CT served as the reference standard for determining the accuracy of hepatic arteriography and C-arm CT for the detection of extrahepatic shunting. MAA-SPECT/CT revealed extrahepatic shunting in 5 patients (17%). Hepatic arteriography yielded a true negative in 22 (73%), a false negative in 5 (17%), and an unclear result in 3 patients (10%). C-arm CT yield...
Journal of Nuclear Medicine, 2011
Radiolabeled somatostatin analogs represent valuable tools for both in vivo diagnosis and therapy... more Radiolabeled somatostatin analogs represent valuable tools for both in vivo diagnosis and therapy of neuroendocrine tumors (NETs) because of the frequent tumoral overexpression of somatostatin receptors (sst). The 2 compounds most often used in functional imaging with PET are 68 Ga-DOTATATE and 68 Ga-DOTATOC. Both ligands share a quite similar sst binding profile. However, the in vitro affinity of 68 Ga-DOTATATE in binding the sst subtype 2 (sst2) is approximately 10-fold higher than that of 68 Ga-DOTATOC. This difference may affect their efficiency in the detection of NET lesions because it is the sst2 that is predominantly overexpressed in NET. We thus compared the diagnostic value of PET/CT with both radiolabeled somatostatin analogs ( 68 Ga-DOTATATE and 68 Ga-DOTATOC) in the same NET patients. Methods: Forty patients with metastatic NETs underwent 68 Ga-DOTATOC and 68 Ga-DOTATATE PET/CT as part of the work-up before prospective peptide receptor radionuclide therapy. The performance of both imaging methods was analyzed and compared for the detection of individual lesions per patient and for 8 defined body regions. A region was regarded positive if at least 1 lesion was detected in that region. In addition, radiopeptide uptake in terms of the maximal standardized uptake value (SUVmax) was compared for concordant lesions and renal parenchyma. Results: Seventy-eight regions were found positive with 68 Ga-DOTATATE versus 79 regions with 68 Ga-DOTATOC (not significant). Overall, however, significantly fewer lesions were detected with 68 Ga-DOTATATE than with 68 Ga-DOTATOC (254 vs. 262, P , 0.05). Mean 68 Ga-DOTATATE SUVmax across all lesions was significantly lower than 68 Ga-DOTATOC (16.0 6 10.8 vs. 20.4 6 14.7, P , 0.01). Mean SUVmax for renal parenchyma was not significantly different between 68 Ga-DOTATATE and 68 Ga-DOTATOC (12.7 6 3.0 vs. 13.2 6 3.3). Conclusion: 68 Ga-DOTATOC and 68 Ga-DOTATATE possess a comparable diagnostic accuracy for the detection of NET lesions, with 68 Ga-DOTATOC having a potential advantage. The approximately 10-fold higher affinity for the sst2 of 68 Ga-DOTATATE does not prove to be clinically relevant. Quite unexpectedly, SUVmax of 68 Ga-DOTATOC scans tended to be higher than their 68 Ga-DOTATATE counterparts.
Journal of Nuclear Medicine, 2009
Radioembolization with 90 Y microspheres is a novel treatment for hepatic tumors. Generally, hepa... more Radioembolization with 90 Y microspheres is a novel treatment for hepatic tumors. Generally, hepatic arteriography and 99m Tc-macroaggregated albumin (MAA) scanning are performed before selective internal radiation therapy to detect extrahepatic shunting to the lung or the gastrointestinal tract. Whereas previous studies have used only planar or SPECT scans, the present study used 99m Tc-MAA SPECT/CT scintigraphy (SPECT with integrated low-dose CT) to evaluate whether SPECT/CT and additional diagnostic contrast-enhanced CT before radioembolization with 90 Y microspheres are superior to SPECT or planar imaging alone for detection of gastrointestinal shunting. Methods: In a prospective study, we enrolled 58 patients (mean age, 66 y; SD, 12 y; 10 women and 48 men) with hepatocellular carcinoma who underwent hepatic arteriography and scintigraphy with 99m Tc-MAA using planar imaging, SPECT, and SPECT with integrated low-dose CT of the upper abdomen (acquired with a hybrid SPECT/CT camera). The ability of the different imaging modalities to detect extrahepatic MAA shunting was compared. Patient follow-up of a mean of 180 d served as the standard of reference. Results: Gastrointestinal shunting was revealed by planar imaging in 4, by SPECT in 9, and by SPECT/CT in 16 of the 68 examinations. For planar imaging, the sensitivity for detection of gastrointestinal shunting was 25%, the specificity 87%, and the accuracy 72%. For SPECT without CT, the sensitivity was 56%, the specificity 87%, and the accuracy 79%. SPECT with CT fusion had a sensitivity of 100%, a specificity of 94%, and an accuracy of 96%. In 3 patients, MAA deposits in the portal vein could accurately be attributed to tumor thrombus only with additional information from contrast-enhanced CT. The follow-up did not show any gastrointestinal complications. Conclusion: SPECT with integrated low-dose CT using 99m Tc-MAA is beneficial in radioembolization with 90 Y microspheres because it increases the sensitivity and specificity of 99m Tc-MAA SPECT when detecting extrahepatic arterial shunting. The overall low risk of gastrointestinal complications in radioembolization may therefore be further reduced by SPECT/CT.
European Journal of Radiology, Jan 6, 2009
Positron emission tomography (PET) and computed tomography (CT) complement each other's strengths... more Positron emission tomography (PET) and computed tomography (CT) complement each other's strengths in integrated PET/CT. PET is a highly sensitive modality to depict the whole-body distribution of positronemitting biomarkers indicating tumour metabolic activity. However, conventional PET imaging is lacking detailed anatomical information to precisely localise pathologic findings. CT imaging can readily provide the required morphological data. Thus, integrated PET/CT represents an efficient tool for whole-body staging and functional assessment within one examination. Due to developments in system technology PET/CT devices are continually gaining spatial resolution and imaging speed. Whole-body imaging from the head to the upper thighs is accomplished in less than 20 min. Spatial resolution approaches 2-4 mm. Most PET/CT studies in oncology are performed with 18 F-labelled fluoro-deoxy-d-glucose (FDG). FDG is a glucose analogue that is taken up and trapped within viable cells. An increased glycolytic activity is a characteristic in many types of cancers resulting in avid accumulation of FDG. These tumours excel as "hot spots" in FDG-PET/CT imaging. FDG-PET/CT proved to be of high diagnostic value in staging and restaging of different malignant diseases, such as colorectal cancer, lung cancer, breast cancer, head and neck cancer, malignant lymphomas, and many more. The standard whole-body coverage simplifies staging and speeds up decision processes to determine appropriate therapeutic strategies. Further development and implementation of new PET-tracers in clinical routine will continually increase the number of PET/CT indications. This promotes PET/CT as the imaging modality of choice for working-up of the most common tumour entities as well as some of the rare malignancies.
European Journal of Nuclear Medicine and Molecular Imaging, 2014
The aim of this study was to evaluate the positron emission tomography (PET) component of [(18)F]... more The aim of this study was to evaluate the positron emission tomography (PET) component of [(18)F]choline PET/MRI and compare it with the PET component of [(18)F]choline PET/CT in patients with histologically proven prostate cancer and suspected recurrent prostate cancer. Thirty-six patients were examined with simultaneous [(18)F]choline PET/MRI following combined [(18)F]choline PET/CT. Fifty-eight PET-positive lesions in PET/CT and PET/MRI were evaluated by measuring the maximum and mean standardized uptake values (SUVmax and SUVmean) using volume of interest (VOI) analysis. A scoring system was applied to determine the quality of the PET images of both PET/CT and PET/MRI. Agreement between PET/CT and PET/MRI regarding SUVmax and SUVmean was tested using Pearson's product-moment correlation and Bland-Altman analysis. All PET-positive lesions that were visible on PET/CT were also detectable on PET/MRI. The quality of the PET images was comparable in both groups. Median SUVmax and SUVmean of all lesions were significantly lower in PET/MRI than in PET/CT (5.2 vs 6.1, p<0.05 and 2.0 vs 2.6, p<0.001, respectively). Pearson's product-moment correlation indicated highly significant correlations between SUVmax of PET/CT and PET/MRI (R=0.86, p<0.001) as well as between SUVmean of PET/CT and PET/MRI (R=0.81, p<0.001). Bland-Altman analysis revealed lower and upper limits of agreement of -2.77 to 3.64 between SUVmax of PET/CT vs PET/MRI and -1.12 to +2.23 between SUVmean of PET/CT vs PET/MRI. PET image quality of PET/MRI was comparable to that of PET/CT. A highly significant correlation between SUVmax and SUVmean was found. Both SUVmax and SUVmean were significantly lower in [(18)F]choline PET/MRI than in [(18)F]choline PET/CT. Differences of SUVmax and SUVmean might be caused by different techniques of attenuation correction. Furthermore, differences in biodistribution and biokinetics of [(18)F]choline between the subsequent examinations and in the respective organ systems have to be taken into account.
Consciousness and Cognition, 2008
One problem of interpreting research on subconscious processing is the possibility that participa... more One problem of interpreting research on subconscious processing is the possibility that participants are weakly conscious of the stimuli. Here, we compared the fMRI BOLD response in healthy adults to clearly visible single letters (supraliminal presentation) with the response to letters presented in the absence of any behavioural evidence of visibility (subliminal presentation). No letter catch trials served as a control condition. Forced-choice responses did not differ from chance when letter-to-background contrast was low, whereas they were almost 100% correct when contrast was high. A comparison of fMRI BOLD signals for supraliminal and subliminal letters with the control trials revealed a signal increase in left BA 37 (fusiform gyrus). Comparison of supraliminal with subliminal letters showed a significant increase in the right inferior frontal gyrus (BA 44, partly extending to BA 9 and BA 45, as well as BA 46). Finally, a comparison of subliminal with supraliminal letters showed increases in the left middle temporal gyrus (BA 21) and the right extrastriate cortex (BA 19).
Dissociations in the ability to produce words of different grammatical categories are well establ... more Dissociations in the ability to produce words of different grammatical categories are well established in neuropsychology but have not been corroborated fully with evidence from brain imaging. Here we report on a PET study designed to reveal the anatomical correlates of grammatical processes involving nouns and verbs. German-speaking subjects were asked to produce either plural and singular nouns, or first-person plural and singular verbs. Verbs, relative to nouns, activated a left frontal cortical network, while the opposite contrast (nouns-verbs) showed greater activation in temporal regions bilaterally. Similar patterns emerged when subjects performed the task with pseudowords used as nouns or as verbs. These results converge with findings from lesion studies and suggest that grammatical category is an important dimension of organization for knowledge of language in the brain. D
Aim: Huntington’s disease (HD) is an autosomal‐dominant progressive neurodegenerative disorder wi... more Aim: Huntington’s disease (HD) is an autosomal‐dominant progressive neurodegenerative disorder with midlife onset, but the disorder can manifest at any time between infancy and senescence. HD is characterised by motor, psychiatric and cognitive symptoms. The hallmark of neuropathology is the progressive loss of medium‐sized spiny neurones in the corpus striatum, which exhibit a high density of dopamine D1 and D2 receptors. C‐11‐raclopride (RAC) can be used for quantitative imaging of postsynaptic dopamine D2 receptor binding sites in PET. The aim of the present study was to verify whether RAC PET proves useful in the longitudinal assessment of striatal dopaminergic D2 receptor binding in HD. Methods: 40 patients suffering from HD underwent serial RAC PET and MRI scans at baseline and after 3 years. PET data were acquired with a Siemens ECAT EXACT scanner. Parametric images of RAC binding potential (BP) were estimated with receptor parametric mapping software using a simplified refer...
Nuklearmedizin. Nuclear medicine, 2015
This document describes the guideline for peptide receptor radionuclide therapy (PRRT) published ... more This document describes the guideline for peptide receptor radionuclide therapy (PRRT) published by the German Society of Nuclear Medicine (DGN) and accepted by the Association of the Scientific Medical Societies in Germany (AWMF) to be included in the official AWMF Guideline Registry. These recommendations are a prerequisite for the quality management in the treatment of patients with somatostatin receptor expressing tumours using PRRT. They are aimed at guiding nuclear medicine specialists in selecting likely candidates to receive PRRT and to deliver the treatment in a safe and effective manner. The recommendations are based on an interdisciplinary consensus. The document contains background information and definitions and covers the rationale, indications and contraindications for PRRT. Essential topics are the requirements for institutions performing the therapy, e. g. presence of an expert for medical physics, intense cooperation with all colleagues involved in the treatment of...
European heart journal, 2015
![Research paper thumbnail of Combined PET imaging and diffusion-weighted imaging of intermediate and high-risk primary prostate carcinomas with simultaneous [18F] choline PET/MRI](https://attachments.academia-assets.com/48178722/thumbnails/1.jpg)
](PloS one, 2014
To characterize intermediate and high-risk prostate carcinomas with measurements of standardized ... more To characterize intermediate and high-risk prostate carcinomas with measurements of standardized uptake values (SUVs) and apparent diffusion coefficient (ADC) values by means of simultaneous [18F] choline PET/MRI. 35 patients with primary prostate cancer underwent simultaneous [18F] choline PET/MRI. From these, 21 patients with an intermediate and high risk constellation who were not under ongoing hormonal therapy were included. Altogether 32 tumor lesions with a focal uptake of [18F] choline could be identified. Average ADC values (ADCaver) minimum ADC values (ADCmin) as well as maximum and mean SUVs (SUVmax, SUVmean) of tumor lesions were assessed with volume-of-interest (VOI) and Region-of-interest (ROI) measurements. As a reference, also ADCaver, ADCmin and SUVmax and SUVmean of non-tumorous prostate tissue were measured. Statistical analysis comprised calculation of descriptive parameters and calculation of Pearson's product moment correlations between ADC values and SUVs o...
RöFo : Fortschritte auf dem Gebiete der Röntgenstrahlen und der Nuklearmedizin, 2010
To retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahe... more To retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahepatic shunting before SIRT. 30 patients (mean age: 64+/-12 years) with hypervascularized hepatic tumors underwent hepatic angiography, coil embolization of gastrointestinal collaterals and 99mTc-macroaggregated albumin (MAA) SPECT/CT before SIRT. Before MAA injection via a microcatheter from the intended treatment position, an angiography and angiography-based C-arm CT (XperCT, Philips Healthcare) were acquired. Angiographies and XperCT were performed from 48 microcatheter positions followed by MAA injections and MAA-SPECT/CT. MAA-SPECT/CT served as the reference standard for determining the accuracy of hepatic arteriography and C-arm CT for the detection of extrahepatic shunting. MAA-SPECT/CT revealed extrahepatic shunting in 5 patients (17%). Hepatic arteriography yielded a true negative in 22 (73%), a false negative in 5 (17%), and an unclear result in 3 patients (10%). C-arm CT yield...
NeuroImage, 2008
To assess the effect of caffeine on the functional MRI signal during a 2-back verbal working memo... more To assess the effect of caffeine on the functional MRI signal during a 2-back verbal working memory task, we examined blood oxygenation level-dependent regional brain activity in 15 healthy right-handed males. The subjects, all moderate caffeine consumers, underwent two scanning sessions on a 1.5-T MR-Scanner separated by a 24- to 48-h interval. Each participant received either placebo or 100 mg caffeine 20 min prior to the performance of the working memory task in blinded crossover fashion. The study was implemented as a blocked-design. Analysis was performed using SPM2. In both conditions, the characteristic working memory network of frontoparietal cortical activation including the precuneus and the anterior cingulate could be shown. In comparison to placebo, caffeine caused an increased response in the bilateral medial frontopolar cortex (BA 10), extending to the right anterior cingulate cortex (BA 32). These results suggest that caffeine modulates neuronal activity as evidenced ...
Nuklearmedizin. Nuclear medicine, 2005
Ventricular arrhythmias have been shown to originate in the myocardial peri-infarct region due to... more Ventricular arrhythmias have been shown to originate in the myocardial peri-infarct region due to irregular heterotopic conduction. Hypoperfused but viable myocardium is often localised in those areas and may be involved in the pathogenesis of arrhythmias. We tested the hypothesis that these myocardial perfusion/metabolism mismatches (MM) are significantly associated with ventricular arrhythmias in the chronic post infarction state. 47 post infarction patients were included in the study. 33 suffered from ventricular arrhythmia whereas 14 did not. All patients underwent (99m)Tc tetrofosmin SPECT and (18)F-FDG PET. A region-of-interest(ROI)-analysis was used to assess viable myocardium based on predefined MM-criteria. Univariate analyses as well as a logistic regression model for the multivariate analysis were carried out. 94% of the arrhythmic patients displayed at least one MM-segment as compared to 64% of the non-arrhythmic patients. MM-segments and arrhythmia showed a statisticall...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2015
The objective of the present study was to evaluate whether integrated (18)F-FDG PET/MR imaging co... more The objective of the present study was to evaluate whether integrated (18)F-FDG PET/MR imaging could improve the diagnostic workup in patients with cardiac masses. Twenty patients were prospectively assessed using integrated cardiac (18)F-FDG PET/MR imaging: 16 patients with cardiac masses of unknown identity and 4 patients with cardiac sarcoma after surgical therapy. All scans were obtained on an integrated 3-T PET/MR device. The MR protocol consisted of half Fourier acquisition single-shot turbo spin-echo sequence, cine, and T2-weighted images as well as T1-weighted images before and after injection of gadobutrol. PET data were acquired simultaneously with the MR scan after injection of 199 ± 58 MBq of (18)F-FDG. Patients were prepared with a high-fat, low-carbohydrate diet in a period of 24 h before the examination, and 50 IU/kg of unfractionated heparin were administered intravenously 15 min before (18)F-FDG injection. Cardiac masses were diagnosed as follows: metastases, 3; dir...
European Journal of Nuclear Medicine and Molecular Imaging, 2015
Annals of the Rheumatic Diseases, 2013
ABSTRACT Background PET is a nuclear imaging technique that depicts functional processes within t... more ABSTRACT Background PET is a nuclear imaging technique that depicts functional processes within the body by detecting pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), introduced into the body on a biologically active molecule. 3D images of tracer concentration are then constructed by computer analysis. The biologically active molecule used for PET is 18F labeled Fluoride (18F-F), a bone-seeking agent reflecting bone perfusion and remodeling. The concentrations of tracer image tissue metabolic activity, in terms of regional bone remodeling. PET scans are increasingly read alongside CT or MRI scans, with the combination (“co-registration”) giving both anatomic and metabolic information, e.g. what the structure is, and what it is doing biochemically. Objectives Based on our long experience with MRIs of patients with axSpA we have inaugurated a pilot study with simultaneous PET/MRI in order to examine whether the addition of the PET technique may provide different and additional information in comparison to MRI alone. Methods Eleven axSpA patients, median age 39 years, disease duration range 0.5-10 years, mean BASDAI 5.3, most of them fulfilling the NY criteria for AS, were examined by PET/3-Tesla MRI 40 minutes after injection of a mean dose of 157 MBq of 18F-F using a hybrid whole-body PET/MRI scanner (Siemens Biograph mMR®). 3T-MRIs were scored blinded to patient’s clinical characteristics by two readers (1 rheumatologist and 1 radiologist) using the Berlin MRI score and also by recording inflammatory lesions on a vertebral edge (VE) level. In a second step PET/MRIs were read blindly by the same readers also based on the VE involvement of individual vertebral bodies. Results Acquisition of whole-spine hybrid 18F-F PET/MRI scans was successful in all patients. The resulting mean effective radiation dose per patient was 3.76 mSv. Co-registration of PET/MRI fusion images was highly accurate and allowed a precise comparison of MRI and PET findings. The mean Berlin MRI score was 6.8 (range 0 – 31). In the direct comparison of the MRI and PET signal the two readers saw consistent signals in almost 90% of the sites studied. However, there were some areas where signals differed, for example within existing syndesmophytes where the PET signal was increased but conventional MRIs showed no signal of active inflammation, or the area of sternum and lateral or posterior spinal elements such as facet joints and spinous process. Conclusions The new technique of combining the PET and MRI provides largely similar imaging signals as conventional MRI. However, we did observe differences between the two techniques - especially in areas with less inflammatory activity where bone metabolism seemed to be active or in areas with blurred resolution on conventional MRI. More studies are needed to answer the question whether the differences between these techniques are pathogenically relevant, whether they can be reliably reproduced and quantified, and, of course, whether they are sensitive to change. Especially the possibility that PET detects osteoblastic activity in areas where no inflammatory signal is detected seems to be of interest. Disclosure of Interest None Declared
Annals of the Rheumatic Diseases
Background PET is a nuclear imaging technique that depicts functional processes within the body b... more Background PET is a nuclear imaging technique that depicts functional processes within the body by detecting pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), introduced into the body on a biologically active molecule. 3D images of tracer concentration are then constructed by computer analysis. The biologically active molecule used for PET is 18F labeled Fluoride (18F-F), a bone-seeking agent reflecting bone perfusion and remodeling. The concentrations of tracer image tissue metabolic activity, in terms of regional bone remodeling. PET scans are increasingly read alongside CT or MRI scans, with the combination (“co-registration”) giving both anatomic and metabolic information, e.g. what the structure is, and what it is doing biochemically. Objectives Based on our long experience with MRIs of patients with axSpA we have inaugurated a pilot study with simultaneous PET/MRI in order to examine whether the addition of the PET technique may provide diffe...
The quarterly journal of nuclear medicine and molecular imaging : official publication of the Italian Association of Nuclear Medicine (AIMN) [and] the International Association of Radiopharmacology (IAR), [and] Section of the Society of..., Jan 8, 2015
A retrospective study using PET/CT imaging with 124I--labeled metaiodobenzylguanidine (124I--MIBG... more A retrospective study using PET/CT imaging with 124I--labeled metaiodobenzylguanidine (124I--MIBG) was performed to estimate the (radiation) absorbed dose to the salivary glands in neuroendocrine cancer patients undergoing 131I--MIBG therapy and to compare these results with those in radioiodine (131I--iodide) therapy. Twenty--seven patients received individual 124I--MIBG--PET/CT dosimetries, among whom 18 had not previously undergone any MIBG therapies (patient group before treatment) and 9 had already received MIBG therapies prior to the tracer dosimetries (patient group after treatment). For each patient, three or four 124I--MIBG PET/CT scans were performed at approximately 4 and 24 h, as well as at approximately 48 or/and ≥96 h after tracer injection. The absorbed doses per administered 131I--MIBG activity to the submandibular and parotid glands were calculated based on the MIRD concept, with its assumption of an uniform glandular activity distribution. The mean±standard deviati...
PloS one, 2014
To characterize intermediate and high-risk prostate carcinomas with measurements of standardized ... more To characterize intermediate and high-risk prostate carcinomas with measurements of standardized uptake values (SUVs) and apparent diffusion coefficient (ADC) values by means of simultaneous [18F] choline PET/MRI. 35 patients with primary prostate cancer underwent simultaneous [18F] choline PET/MRI. From these, 21 patients with an intermediate and high risk constellation who were not under ongoing hormonal therapy were included. Altogether 32 tumor lesions with a focal uptake of [18F] choline could be identified. Average ADC values (ADCaver) minimum ADC values (ADCmin) as well as maximum and mean SUVs (SUVmax, SUVmean) of tumor lesions were assessed with volume-of-interest (VOI) and Region-of-interest (ROI) measurements. As a reference, also ADCaver, ADCmin and SUVmax and SUVmean of non-tumorous prostate tissue were measured. Statistical analysis comprised calculation of descriptive parameters and calculation of Pearson's product moment correlations between ADC values and SUVs o...
RöFo : Fortschritte auf dem Gebiete der Röntgenstrahlen und der Nuklearmedizin, 2010
To retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahe... more To retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahepatic shunting before SIRT. 30 patients (mean age: 64+/-12 years) with hypervascularized hepatic tumors underwent hepatic angiography, coil embolization of gastrointestinal collaterals and 99mTc-macroaggregated albumin (MAA) SPECT/CT before SIRT. Before MAA injection via a microcatheter from the intended treatment position, an angiography and angiography-based C-arm CT (XperCT, Philips Healthcare) were acquired. Angiographies and XperCT were performed from 48 microcatheter positions followed by MAA injections and MAA-SPECT/CT. MAA-SPECT/CT served as the reference standard for determining the accuracy of hepatic arteriography and C-arm CT for the detection of extrahepatic shunting. MAA-SPECT/CT revealed extrahepatic shunting in 5 patients (17%). Hepatic arteriography yielded a true negative in 22 (73%), a false negative in 5 (17%), and an unclear result in 3 patients (10%). C-arm CT yield...
Journal of Nuclear Medicine, 2011
Radiolabeled somatostatin analogs represent valuable tools for both in vivo diagnosis and therapy... more Radiolabeled somatostatin analogs represent valuable tools for both in vivo diagnosis and therapy of neuroendocrine tumors (NETs) because of the frequent tumoral overexpression of somatostatin receptors (sst). The 2 compounds most often used in functional imaging with PET are 68 Ga-DOTATATE and 68 Ga-DOTATOC. Both ligands share a quite similar sst binding profile. However, the in vitro affinity of 68 Ga-DOTATATE in binding the sst subtype 2 (sst2) is approximately 10-fold higher than that of 68 Ga-DOTATOC. This difference may affect their efficiency in the detection of NET lesions because it is the sst2 that is predominantly overexpressed in NET. We thus compared the diagnostic value of PET/CT with both radiolabeled somatostatin analogs ( 68 Ga-DOTATATE and 68 Ga-DOTATOC) in the same NET patients. Methods: Forty patients with metastatic NETs underwent 68 Ga-DOTATOC and 68 Ga-DOTATATE PET/CT as part of the work-up before prospective peptide receptor radionuclide therapy. The performance of both imaging methods was analyzed and compared for the detection of individual lesions per patient and for 8 defined body regions. A region was regarded positive if at least 1 lesion was detected in that region. In addition, radiopeptide uptake in terms of the maximal standardized uptake value (SUVmax) was compared for concordant lesions and renal parenchyma. Results: Seventy-eight regions were found positive with 68 Ga-DOTATATE versus 79 regions with 68 Ga-DOTATOC (not significant). Overall, however, significantly fewer lesions were detected with 68 Ga-DOTATATE than with 68 Ga-DOTATOC (254 vs. 262, P , 0.05). Mean 68 Ga-DOTATATE SUVmax across all lesions was significantly lower than 68 Ga-DOTATOC (16.0 6 10.8 vs. 20.4 6 14.7, P , 0.01). Mean SUVmax for renal parenchyma was not significantly different between 68 Ga-DOTATATE and 68 Ga-DOTATOC (12.7 6 3.0 vs. 13.2 6 3.3). Conclusion: 68 Ga-DOTATOC and 68 Ga-DOTATATE possess a comparable diagnostic accuracy for the detection of NET lesions, with 68 Ga-DOTATOC having a potential advantage. The approximately 10-fold higher affinity for the sst2 of 68 Ga-DOTATATE does not prove to be clinically relevant. Quite unexpectedly, SUVmax of 68 Ga-DOTATOC scans tended to be higher than their 68 Ga-DOTATATE counterparts.
Journal of Nuclear Medicine, 2009
Radioembolization with 90 Y microspheres is a novel treatment for hepatic tumors. Generally, hepa... more Radioembolization with 90 Y microspheres is a novel treatment for hepatic tumors. Generally, hepatic arteriography and 99m Tc-macroaggregated albumin (MAA) scanning are performed before selective internal radiation therapy to detect extrahepatic shunting to the lung or the gastrointestinal tract. Whereas previous studies have used only planar or SPECT scans, the present study used 99m Tc-MAA SPECT/CT scintigraphy (SPECT with integrated low-dose CT) to evaluate whether SPECT/CT and additional diagnostic contrast-enhanced CT before radioembolization with 90 Y microspheres are superior to SPECT or planar imaging alone for detection of gastrointestinal shunting. Methods: In a prospective study, we enrolled 58 patients (mean age, 66 y; SD, 12 y; 10 women and 48 men) with hepatocellular carcinoma who underwent hepatic arteriography and scintigraphy with 99m Tc-MAA using planar imaging, SPECT, and SPECT with integrated low-dose CT of the upper abdomen (acquired with a hybrid SPECT/CT camera). The ability of the different imaging modalities to detect extrahepatic MAA shunting was compared. Patient follow-up of a mean of 180 d served as the standard of reference. Results: Gastrointestinal shunting was revealed by planar imaging in 4, by SPECT in 9, and by SPECT/CT in 16 of the 68 examinations. For planar imaging, the sensitivity for detection of gastrointestinal shunting was 25%, the specificity 87%, and the accuracy 72%. For SPECT without CT, the sensitivity was 56%, the specificity 87%, and the accuracy 79%. SPECT with CT fusion had a sensitivity of 100%, a specificity of 94%, and an accuracy of 96%. In 3 patients, MAA deposits in the portal vein could accurately be attributed to tumor thrombus only with additional information from contrast-enhanced CT. The follow-up did not show any gastrointestinal complications. Conclusion: SPECT with integrated low-dose CT using 99m Tc-MAA is beneficial in radioembolization with 90 Y microspheres because it increases the sensitivity and specificity of 99m Tc-MAA SPECT when detecting extrahepatic arterial shunting. The overall low risk of gastrointestinal complications in radioembolization may therefore be further reduced by SPECT/CT.
European Journal of Radiology, Jan 6, 2009
Positron emission tomography (PET) and computed tomography (CT) complement each other's strengths... more Positron emission tomography (PET) and computed tomography (CT) complement each other's strengths in integrated PET/CT. PET is a highly sensitive modality to depict the whole-body distribution of positronemitting biomarkers indicating tumour metabolic activity. However, conventional PET imaging is lacking detailed anatomical information to precisely localise pathologic findings. CT imaging can readily provide the required morphological data. Thus, integrated PET/CT represents an efficient tool for whole-body staging and functional assessment within one examination. Due to developments in system technology PET/CT devices are continually gaining spatial resolution and imaging speed. Whole-body imaging from the head to the upper thighs is accomplished in less than 20 min. Spatial resolution approaches 2-4 mm. Most PET/CT studies in oncology are performed with 18 F-labelled fluoro-deoxy-d-glucose (FDG). FDG is a glucose analogue that is taken up and trapped within viable cells. An increased glycolytic activity is a characteristic in many types of cancers resulting in avid accumulation of FDG. These tumours excel as "hot spots" in FDG-PET/CT imaging. FDG-PET/CT proved to be of high diagnostic value in staging and restaging of different malignant diseases, such as colorectal cancer, lung cancer, breast cancer, head and neck cancer, malignant lymphomas, and many more. The standard whole-body coverage simplifies staging and speeds up decision processes to determine appropriate therapeutic strategies. Further development and implementation of new PET-tracers in clinical routine will continually increase the number of PET/CT indications. This promotes PET/CT as the imaging modality of choice for working-up of the most common tumour entities as well as some of the rare malignancies.
European Journal of Nuclear Medicine and Molecular Imaging, 2014
The aim of this study was to evaluate the positron emission tomography (PET) component of [(18)F]... more The aim of this study was to evaluate the positron emission tomography (PET) component of [(18)F]choline PET/MRI and compare it with the PET component of [(18)F]choline PET/CT in patients with histologically proven prostate cancer and suspected recurrent prostate cancer. Thirty-six patients were examined with simultaneous [(18)F]choline PET/MRI following combined [(18)F]choline PET/CT. Fifty-eight PET-positive lesions in PET/CT and PET/MRI were evaluated by measuring the maximum and mean standardized uptake values (SUVmax and SUVmean) using volume of interest (VOI) analysis. A scoring system was applied to determine the quality of the PET images of both PET/CT and PET/MRI. Agreement between PET/CT and PET/MRI regarding SUVmax and SUVmean was tested using Pearson's product-moment correlation and Bland-Altman analysis. All PET-positive lesions that were visible on PET/CT were also detectable on PET/MRI. The quality of the PET images was comparable in both groups. Median SUVmax and SUVmean of all lesions were significantly lower in PET/MRI than in PET/CT (5.2 vs 6.1, p<0.05 and 2.0 vs 2.6, p<0.001, respectively). Pearson's product-moment correlation indicated highly significant correlations between SUVmax of PET/CT and PET/MRI (R=0.86, p<0.001) as well as between SUVmean of PET/CT and PET/MRI (R=0.81, p<0.001). Bland-Altman analysis revealed lower and upper limits of agreement of -2.77 to 3.64 between SUVmax of PET/CT vs PET/MRI and -1.12 to +2.23 between SUVmean of PET/CT vs PET/MRI. PET image quality of PET/MRI was comparable to that of PET/CT. A highly significant correlation between SUVmax and SUVmean was found. Both SUVmax and SUVmean were significantly lower in [(18)F]choline PET/MRI than in [(18)F]choline PET/CT. Differences of SUVmax and SUVmean might be caused by different techniques of attenuation correction. Furthermore, differences in biodistribution and biokinetics of [(18)F]choline between the subsequent examinations and in the respective organ systems have to be taken into account.
Consciousness and Cognition, 2008
One problem of interpreting research on subconscious processing is the possibility that participa... more One problem of interpreting research on subconscious processing is the possibility that participants are weakly conscious of the stimuli. Here, we compared the fMRI BOLD response in healthy adults to clearly visible single letters (supraliminal presentation) with the response to letters presented in the absence of any behavioural evidence of visibility (subliminal presentation). No letter catch trials served as a control condition. Forced-choice responses did not differ from chance when letter-to-background contrast was low, whereas they were almost 100% correct when contrast was high. A comparison of fMRI BOLD signals for supraliminal and subliminal letters with the control trials revealed a signal increase in left BA 37 (fusiform gyrus). Comparison of supraliminal with subliminal letters showed a significant increase in the right inferior frontal gyrus (BA 44, partly extending to BA 9 and BA 45, as well as BA 46). Finally, a comparison of subliminal with supraliminal letters showed increases in the left middle temporal gyrus (BA 21) and the right extrastriate cortex (BA 19).
Dissociations in the ability to produce words of different grammatical categories are well establ... more Dissociations in the ability to produce words of different grammatical categories are well established in neuropsychology but have not been corroborated fully with evidence from brain imaging. Here we report on a PET study designed to reveal the anatomical correlates of grammatical processes involving nouns and verbs. German-speaking subjects were asked to produce either plural and singular nouns, or first-person plural and singular verbs. Verbs, relative to nouns, activated a left frontal cortical network, while the opposite contrast (nouns-verbs) showed greater activation in temporal regions bilaterally. Similar patterns emerged when subjects performed the task with pseudowords used as nouns or as verbs. These results converge with findings from lesion studies and suggest that grammatical category is an important dimension of organization for knowledge of language in the brain. D
Aim: Huntington’s disease (HD) is an autosomal‐dominant progressive neurodegenerative disorder wi... more Aim: Huntington’s disease (HD) is an autosomal‐dominant progressive neurodegenerative disorder with midlife onset, but the disorder can manifest at any time between infancy and senescence. HD is characterised by motor, psychiatric and cognitive symptoms. The hallmark of neuropathology is the progressive loss of medium‐sized spiny neurones in the corpus striatum, which exhibit a high density of dopamine D1 and D2 receptors. C‐11‐raclopride (RAC) can be used for quantitative imaging of postsynaptic dopamine D2 receptor binding sites in PET. The aim of the present study was to verify whether RAC PET proves useful in the longitudinal assessment of striatal dopaminergic D2 receptor binding in HD. Methods: 40 patients suffering from HD underwent serial RAC PET and MRI scans at baseline and after 3 years. PET data were acquired with a Siemens ECAT EXACT scanner. Parametric images of RAC binding potential (BP) were estimated with receptor parametric mapping software using a simplified refer...
Nuklearmedizin. Nuclear medicine, 2015
This document describes the guideline for peptide receptor radionuclide therapy (PRRT) published ... more This document describes the guideline for peptide receptor radionuclide therapy (PRRT) published by the German Society of Nuclear Medicine (DGN) and accepted by the Association of the Scientific Medical Societies in Germany (AWMF) to be included in the official AWMF Guideline Registry. These recommendations are a prerequisite for the quality management in the treatment of patients with somatostatin receptor expressing tumours using PRRT. They are aimed at guiding nuclear medicine specialists in selecting likely candidates to receive PRRT and to deliver the treatment in a safe and effective manner. The recommendations are based on an interdisciplinary consensus. The document contains background information and definitions and covers the rationale, indications and contraindications for PRRT. Essential topics are the requirements for institutions performing the therapy, e. g. presence of an expert for medical physics, intense cooperation with all colleagues involved in the treatment of...
European heart journal, 2015
PloS one, 2014
To characterize intermediate and high-risk prostate carcinomas with measurements of standardized ... more To characterize intermediate and high-risk prostate carcinomas with measurements of standardized uptake values (SUVs) and apparent diffusion coefficient (ADC) values by means of simultaneous [18F] choline PET/MRI. 35 patients with primary prostate cancer underwent simultaneous [18F] choline PET/MRI. From these, 21 patients with an intermediate and high risk constellation who were not under ongoing hormonal therapy were included. Altogether 32 tumor lesions with a focal uptake of [18F] choline could be identified. Average ADC values (ADCaver) minimum ADC values (ADCmin) as well as maximum and mean SUVs (SUVmax, SUVmean) of tumor lesions were assessed with volume-of-interest (VOI) and Region-of-interest (ROI) measurements. As a reference, also ADCaver, ADCmin and SUVmax and SUVmean of non-tumorous prostate tissue were measured. Statistical analysis comprised calculation of descriptive parameters and calculation of Pearson's product moment correlations between ADC values and SUVs o...
RöFo : Fortschritte auf dem Gebiete der Röntgenstrahlen und der Nuklearmedizin, 2010
To retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahe... more To retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahepatic shunting before SIRT. 30 patients (mean age: 64+/-12 years) with hypervascularized hepatic tumors underwent hepatic angiography, coil embolization of gastrointestinal collaterals and 99mTc-macroaggregated albumin (MAA) SPECT/CT before SIRT. Before MAA injection via a microcatheter from the intended treatment position, an angiography and angiography-based C-arm CT (XperCT, Philips Healthcare) were acquired. Angiographies and XperCT were performed from 48 microcatheter positions followed by MAA injections and MAA-SPECT/CT. MAA-SPECT/CT served as the reference standard for determining the accuracy of hepatic arteriography and C-arm CT for the detection of extrahepatic shunting. MAA-SPECT/CT revealed extrahepatic shunting in 5 patients (17%). Hepatic arteriography yielded a true negative in 22 (73%), a false negative in 5 (17%), and an unclear result in 3 patients (10%). C-arm CT yield...
NeuroImage, 2008
To assess the effect of caffeine on the functional MRI signal during a 2-back verbal working memo... more To assess the effect of caffeine on the functional MRI signal during a 2-back verbal working memory task, we examined blood oxygenation level-dependent regional brain activity in 15 healthy right-handed males. The subjects, all moderate caffeine consumers, underwent two scanning sessions on a 1.5-T MR-Scanner separated by a 24- to 48-h interval. Each participant received either placebo or 100 mg caffeine 20 min prior to the performance of the working memory task in blinded crossover fashion. The study was implemented as a blocked-design. Analysis was performed using SPM2. In both conditions, the characteristic working memory network of frontoparietal cortical activation including the precuneus and the anterior cingulate could be shown. In comparison to placebo, caffeine caused an increased response in the bilateral medial frontopolar cortex (BA 10), extending to the right anterior cingulate cortex (BA 32). These results suggest that caffeine modulates neuronal activity as evidenced ...
Nuklearmedizin. Nuclear medicine, 2005
Ventricular arrhythmias have been shown to originate in the myocardial peri-infarct region due to... more Ventricular arrhythmias have been shown to originate in the myocardial peri-infarct region due to irregular heterotopic conduction. Hypoperfused but viable myocardium is often localised in those areas and may be involved in the pathogenesis of arrhythmias. We tested the hypothesis that these myocardial perfusion/metabolism mismatches (MM) are significantly associated with ventricular arrhythmias in the chronic post infarction state. 47 post infarction patients were included in the study. 33 suffered from ventricular arrhythmia whereas 14 did not. All patients underwent (99m)Tc tetrofosmin SPECT and (18)F-FDG PET. A region-of-interest(ROI)-analysis was used to assess viable myocardium based on predefined MM-criteria. Univariate analyses as well as a logistic regression model for the multivariate analysis were carried out. 94% of the arrhythmic patients displayed at least one MM-segment as compared to 64% of the non-arrhythmic patients. MM-segments and arrhythmia showed a statisticall...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2015
The objective of the present study was to evaluate whether integrated (18)F-FDG PET/MR imaging co... more The objective of the present study was to evaluate whether integrated (18)F-FDG PET/MR imaging could improve the diagnostic workup in patients with cardiac masses. Twenty patients were prospectively assessed using integrated cardiac (18)F-FDG PET/MR imaging: 16 patients with cardiac masses of unknown identity and 4 patients with cardiac sarcoma after surgical therapy. All scans were obtained on an integrated 3-T PET/MR device. The MR protocol consisted of half Fourier acquisition single-shot turbo spin-echo sequence, cine, and T2-weighted images as well as T1-weighted images before and after injection of gadobutrol. PET data were acquired simultaneously with the MR scan after injection of 199 ± 58 MBq of (18)F-FDG. Patients were prepared with a high-fat, low-carbohydrate diet in a period of 24 h before the examination, and 50 IU/kg of unfractionated heparin were administered intravenously 15 min before (18)F-FDG injection. Cardiac masses were diagnosed as follows: metastases, 3; dir...