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Objectives: Disease patterns (DP) derived from the scaled subprofile model, a principal component analysis based method (SSM/PCA), have been used to successfully identify Alzheimer’s disease (AD) patients based on 18F-FDG PET scans. In the current study, a similar approach was explored with parametric images derived from pharmacokinetic analysis of 11C-Pittsbough Compound B (PIB) to generate DPs based on different imaging characteristics of the disease. Methods: Pharmacokinetic modeling using the simplified reference tissue model 2 was applied to the dynamic PIB-PET scans of 30 subjects (15 AD and 15 healthy controls). Parametric images of binding potential (BPND) and relative influx of tracer (R1) were used to construct metric-specific DPs. Then Z-scores were assigned to the images based on its similarities with these DPs. Moreover, the subjects were classified based on a specific threshold derived from receiver-operator characteristic curves. Finally, a set of 32 different subjects diagnosed with AD (n = 4), Lewy body dementia (DLB) (n = 5), frontal temporal dementia (FTD) (n = 5), or mild cognitive impairment (MCI) with (+) (n = 11) or without (-) (n = 7) deposits of amyloid-β plaques, were tested against the DPs. Results: Visual inspection of the DPs generated for each method were in line with previous studies: a higher binding (BPND images) and hypoperfusion (R1) were observed in multiple gray matter regions of AD, as compared to healthy subjects. The Z-score threshold for classifying AD patients based on BPND and R1 parametric maps were, respectively, 4.3 (area under the curve (AUC) = 1) and 1.3 (AUC = 0.9). Figure 1 shows the distribution of the Z-scores of the testing subjects. The AD group, as expected, presented an average value above the threshold, of 6.9 ± 6.8 (mean ± SD) for the BPND and 2.0 ± 1.7 for the R1. Meanwhile, the MCI- and DLB groups both presented mean Z-scores smaller than the thresholds (for the DLB group, BPND was of 0.7 ± 1.0 and R1 was 1.0 ± 0.8, and for the MCI-, 0.7 ± 3.1 and 0.8 ± 1.2 respectively). The MCI+ group presented a similar BPND pattern as the AD subjects, with a mean of 14.4 ± 7.2, but the same did not apply to the R1, with a mean of 0.6 ± 0.6. Interestingly, an opposite effect was observed in the FTD group, with high R1 Z-scores (2.1 ± 1.4), and low BPND (–0.4 ± 0.2). Conclusions: Pharmacokinetic modeling of dynamic PIB-PET scans provide high-quality parametric maps, such as BPND and R1, that provide complimentary information. These images can be used as input for a SSM/PCA analysis, resulting in DPs that demonstrate different characteristic of AD patients when compared to healthy subjects. The multiparametric combination of these parametric images showed to be effective for a better discrimination of AD from other dementias.

Purpose/Introduction Glioma vascularization and perfusion are important factors for tumor diagnostics. Dynamic Susceptibility Contrast (DSC) provides a proxy of perfusion by measuring mean transit time and blood volume and is sensitive to blood-brain-barrier breakdown. Arterial spin labeling (ASL) measures true tissue perfusion and can thus provide complementary information to DSC that may aid in tumor grading and in imaging the treatment response to, e.g., antiangiogenic drugs. Agreement of ASL and PET was shown in volunteers 1 . However, ASL can also partly show intravascular signal making ASL imaging of tumors challenging especially in the presence of vascular shunting. We compared ASL and DSC to the gold-standard for perfusion, [ 15 O]H 2 0 PET, to understand their limits as a surrogate of true regional perfusion. Subjects and Methods As part of the FRONTIER study, 8 glioma patients underwent multiple biopsies before scanning using Philips 3T Achieva MR and Gemini PET-CT 2 . PET (10min, 370 MBq of [ 15 O]H 2 0, simultaneous arterial blood sampling), ASL (pCASL 2D EPI, post-labeling delay and labeling duration 1800ms, 3x3x5 mm 3 ), DSC (TR 1.9s, TE 30ms, 1.7x2.4x3.6mm 3 , preloaded contrast) images were acquired. Cerebral blood flow (CBF) was quantified for ASL with ExploreASL, for DSC with Olea Sphere 3.0 with AIF obtained manually from MCA 3 . CBF images were aligned to PET and downsampled 6x6x6mm 3 resolution. Mean and voxel-wise CBF was compared between modalities in tumors and in contralateral-hemisphere gray matter (GM). Absolute and relative CBF (divided by subject’s mean whole-hemisphere contralateral GM CBF) were assessed. Results Mean hemispheric and voxelwise GM CBF values in the contralateral hemisphere were compared before and after normalization to global GM mean. For relative CBF, we observed a linear relationship between modalities in the tumor maximum values. Voxelwise analysis shows good agreement of PET and ASL for CBF ratio

Purpose: To evaluate the optimal tracer uptake time, the minimally amount of radioactivity and the inter-observer agree-ment for 11C-choline positron emission tomography/computed tomography (PET/CT) in patients with primary hyperparathy-roidism (pHPT). Subjects & methods: Twenty-one patients with clinically suspected pHPT were retrospectively studied after injection of mean 6.3 ± 1.2 MBq/kg. PET list mode data of the first nine patients, scanned for up to max 60 min, were reconstructed in 10 min frames mimicking varying 11C-choline uptake times from 10 to 60 min postinjection (p.i.) to assess optimal tracer uptake time. Parathyroid adenoma (PTA) to background contrast ratios were calculated, using standardized uptake values (SUVs), and compared. The first time frame in which there were no significant differences compared to later time frames, was considered the optimal uptake time. Also, data was reconstructed with varying durations (1, 2.5 and 5 min) at 20-30 min p.i. (established optimal uptake time), mimicking less administered radioactivity. To establish the minimal radioactivity administered, the variability of SUVs for PTA and thyroid tissue, normalized to 10 min time frame level of the established optimal uptake time (since the individual measurements of SUV per patient varied considerably), was analysed. Furthermore, four observers were asked to analyse the 11C-choline uptake for PET/CT scans in four randomized rounds for all 21 patients, with increasing scan duration per round. P-values of

Large vessel vasculitis (LVV) is defined as a disease mainly affecting the large arteries, with two major variants, Takayasu arteritis (TA) and giant cell arteritis (GCA). GCA often coexists with polymyalgia rheumatica (PMR) in the same patient, since both belong to the same disease spectrum. FDG-PET/CT is a functional imaging technique which is an established tool in oncology, and has also demonstrated a role in the field of inflammatory diseases. Functional FDG-PET combined with anatomical CT angiography, FDG-PET/CT(A), may be of synergistic value for optimal diagnosis, monitoring of disease activity, and evaluating damage progression in LVV. There are currently no guidelines regarding PET imaging acquisition for LVV and PMR, even though standardization is of the utmost importance in order to facilitate clinical studies and for daily clinical practice. This work constitutes a joint procedural recommendation on FDG-PET/CT(A) imaging in large vessel vasculitis (LVV) and PMR from the Cardiovascular and Inflammation & Infection Committees of the European Association of Nuclear Medicine (EANM), the Cardiovascular Council of the Society of Nuclear Medicine and Molecular Imaging (SNMMI), and the PET Interest Group (PIG), and endorsed by the American Society of Nuclear Cardiology (ASNC). The aim of this joint paper is to provide recommendations and statements, based on the available evidence in the literature and consensus of experts in the field, for patient preparation, and FDG-PET/CT(A) acquisition and interpretation for the diagnosis and follow-up of patients with suspected or diagnosed LVV and/or PMR. This position paper aims to set an internationally accepted standard for FDG-PET/CT(A) imaging and reporting of LVV and PMR. Electronic supplementary material The online version of this article (10.1007/s00259-018-3973-8) contains supplementary material, which is available to authorized users.

The 6th annual meeting to address key issues in positron emission tomography (PET)/magnetic resonance imaging (MRI) was held again in Tübingen, Germany, from March 27 to 29, 2017. Over three days of invited plenary lectures, round table discussions and dialogue board deliberations, participants critically assessed the current state of PET/MRI, both clinically and as a research tool, and attempted to chart future directions. The meeting addressed the use of PET/MRI and workflows in oncology, neurosciences, infection, inflammation and chronic pain syndromes, as well as deeper discussions about how best to characterise the tumour microenvironment, optimise the complementary information available from PET and MRI, and how advanced data mining and bioinformatics, as well as information from liquid biomarkers (circulating tumour cells and nucleic acids) and pathology, can be integrated to give a more complete characterisation of disease phenotype. Some issues that have dominated previous meetings, such as the accuracy of MR-based attenuation correction (AC) of the PET scan, were finally put to rest as having been adequately addressed for the majority of clinical situations. Likewise, the ability to standardise PET systems for use in multicentre trials was confirmed, thus removing a perceived barrier to larger clinical imaging trials. The meeting openly questioned whether PET/MRI should, in all cases, be used as a whole-body imaging modality or whether in many circumstances it would best be employed to give an in-depth study of previously identified disease in a single organ or region. The meeting concluded that there is still much work to be done in the integration of data from different fields and in developing a common language for all stakeholders involved. In addition, the participants advocated joint training and education for individuals who engage in routine PET/MRI. It was agreed that PET/MRI can enhance our understanding of normal and disrupted biology, and we are in a position to describe the in vivo nature of disease processes, metabolism, evolution of cancer and the monitoring of response to pharmacological interventions and therapies. As such, PET/MRI is a key to advancing medicine and patient care.

Purpose: This study was conducted to directly compare the high-resolution research tomograph (HRRT) (high-resolution brain) and HR+ (standard whole-body) positron emission tomography (PET) only scanners for quantitative brain studies using three tracers with vastly different tracer distributions.Procedures: Healthy volunteers underwent successive scans on HR+ and HRRT scanners (in random order) using either (R)-[11C]verapamil (n = 6), [11C]raclopride (n = 7) or [11C]flumazenil (n = 7). For all tracers, metabolite-corrected plasma-input functions were generated.Results: After resolution matching, HRRT-derived kinetic parameter values correlated well with those of HR+ for all tracers (intraclass correlation coefficients ≥0.78), having a good absolute interscanner test-retest variability (≤15 %). However, systematic differences can be seen for HRRT-derived kinetic parameter values (range −13 to +15 %).Conclusion: Quantification of kinetic parameters based on plasma-input models leads to comparable results when spatial resolution between HRRT and HR+ data is matched. When using reference-tissue models, differences remain that are likely caused by differences in attenuation and scatter corrections and/or image reconstruction.

Contains fulltext : 177750.pdf (Publisher’s version ) (Open Access) To date, there is no published detailed checklist with parameters referencing the DICOM tag information with respect to the quality control (QC) of PET/CT scans. The aims of these guidelines are to provide the know-how for effectively controlling the quality of PET/CT scans in multicenter studies, to standardize the QC, to give sponsors and regulatory agencies a basis for justification of the data quality when using standardized uptake values as an imaging biomarker, to document the compliance with the imaging guidelines, to verify the per protocol population versus intent to treat population, and to safeguard the validity of multicenter study conclusions employing standardized uptake value (SUV) as an imaging biomarker which is paramount to the scientific community. Following the proposed guidelines will ensure standardized prospective imaging QC of scans applicable to most studies where SUVs are used as an imaging biomarker. The multitude of factors affecting SUV measurements when not controlled inflicts noise on the data. Decisions on patient management with substantial noise would be devastating to patients, ultimately undermine treatment outcome, and invalidate the utility of SUV as an imaging biomarker usefulness. Strict control of the data quality used for the validation of SUV as an imaging biomarker would ensure trust and reliability of the data.

Background: In ALK-positive advanced NSCLC, crizotinib has a high response rate and effectively increases quality of life and survival. CT measurement of the tumor may insufficiently reflect the actual tumor load changes during targeted therapy with crizotinib. We explored whether 18F-FDG PET measured metabolic changes are different from CT based changes and studied the impact of these changes on disease progression. Methods: 18F-FDG PET/CT was performed prior to and after 6 weeks of crizotinib treatment. Tumor response on CT was classified with RECIST 1.1, while 18F-FDG PET response was assessed according to the 1999 EORTC recommendations and PERCIST criteria. Agreement was assessed using McNemars test. During follow-up, patients received additional PET/CT during crizotinib treatment and second generation ALK inhibition. We assessed whether PET was able to detect progression earlier then CT. Results: In this exploratory study 15 patients were analyzed who were treated with crizotinib. There was a good agreement in the applicability of CT and 18F-FDG PET/CT using the EORTC recommendations. During first line crizotinib and subsequent second line ALK inhibitors, PET was able to detect progression earlier then CT in 10/22 (45%) events of progression and in the others disease progression was detected simultaneously. Conclusion: In advanced ALK positive NSCLC PET was able to detect progressive disease earlier than with CT in nearly half of the assessments while both imaging tests performed similar in the others.