PET/MRI in practice: a clinical centre survey endorsed by the European Association of Nuclear Medicine (EANM) and the EANM Forschungs GmbH (EARL)

Hybrid cardiovascular imaging. A clinical consensus statement of the european association of nuclear medicine (EANM) and the european association of cardiovascular imaging (EACVI) of the ESC

Hybrid imaging consists of a combination of two or more imaging modalities, which equally contribute to image information. To date, hybrid cardiovascular imaging can be performed by either merging images acquired on different scanners, or with truly hybrid PET/CT and PET/MR scanners. The European Association of Nuclear Medicine (EANM), and the European Association of Cardiovascular Imaging (EACVI) of the European Society of Cardiology (ESC) aim to review clinical situations that may benefit from the use of hybrid cardiac imaging and provide advice on acquisition protocols providing the most relevant information to reach diagnosis in various clinical situations.

Recent Progress of Cardiac MRI for Nuclear Medicine Professionals

Recent technical innovation enables faster and more reliable cardiac magnetic resonance (CMR) imaging than before. Artificial intelligence is used in improving image resolution, fast scanning, and automated analysis of CMR. Fast CMR techniques such as compressed sensing technique enable fast cine, perfusion, and late gadolinium-enhanced imaging and improve patient throughput and widening CMR indications. CMR feature-tracking technique gives insight on diastolic function parameters of ventricles and atria with prognostic implications. Myocardial parametric mapping became to be included in the routine CMR protocol. CMR fingerprinting enables simultaneous quantification of myocardial T1 and T2. These parameters may give information on myocardial alteration in the preclinical stages in various myocardial diseases. Four-dimensional flow imaging shows hemodynamic characteristics in or through the cardiovascular structures visually and gives quantitative values of vortex, kinetic energy, and wall-shear stress. In conclusion, CMR is an essential modality in the diagnosis of various cardiovascular diseases, especially myocardial diseases. Recent progress in CMR techniques promotes more widespread use of CMR in clinical practice. This review summarizes recent updates in CMR technologies and clinical research.

Diagnostic performance of simultaneous PET-MR versus PET-CT in oncology with an overview on clinical utility and referral pattern of PET-MR: a single institutional study

BACKGROUND

PET-Magnetic Resonance (PET-MR) imaging is an upcoming investigative modality with a few installations in Asia and only three in India. PET-Computed Tomography (PET-CT) is an established diagnostic cornerstone for oncological indications but with limited resolution for small lesions due to low soft-tissue contrast and additional radiation exposure.

OBJECTIVE

Our primary objective was to evaluate the diagnostic performance of simultaneous PET-MR and PET-CT in lesion detection in oncological practice. Secondly to assess the referral pattern and study the clinical utility of PET-MR in a university hospital practice.

MATERIALS AND METHODS

A total of 100 consecutive biopsy-proven cancer patients (breast or lung malignancy with suspected metastases) underwent 18 F Fluorodeoxyglucose (FDG) PET-MR and PET-CT for staging as a single injection, double examination protocol. Morphological lesion detection on correlative imaging/histopathology was used as the gold standard. Analysing the referral pattern, a total of 9366 patients underwent simultaneous PET-MR imaging for various indications in the past 5 years since installation.

RESULTS

18 F FDG PET-MR detected 100% of primary tumours in breast/lung carcinoma patients while PET-CT was positive in 96%. Overall accuracy of nodal metastases detection for PET-MR and PET-CT was 96 and 88%, while for distant metastases the accuracy was 100 and 93%, respectively. FDG PET-MR proved more sensitive and specific than PET-CT for regional nodal ( P  = 0.011 and P  < 0.001) and distant metastases detection ( P  = 0.017 and P < 0.001, respectively). Analysing the general referral pattern for PET-MR, the majority were oncology referrals when compared to nononcological indications (66.5, 33.5%). About 66.24% were FDG based, followed by 68 Ga Prostate-Specific Membrane Antigen (PSMA) and dodecane tetraacetic acid (DOTA). The general utility of PET-MR was found incremental in better delineation of small lesions especially in head, neck, liver, brain and gynaecological malignancies.

CONCLUSION

In our past 5 years of PET-MR practice, we found that simultaneous PET-MR is a highly recommended ideal imaging technique for oncological and nononcological indications. It has excellent diagnostic performance with high sensitivity, specificity and accuracy when compared to PET-CT in primary tumour, nodal and distant metastases (TNM) staging in specific subgroup of breast and lung malignancy patients.

Topographic metabolism-function relationships in Alzheimer's disease: A simultaneous PET/MRI study

Disruptions of neural metabolism and function occur in parallel during Alzheimer's disease (AD). While many studies have shown diverse metabolic-functional relationships in specific brain regions, much less is known about how large-scale network-level functional activity is associated with the topology of metabolism in AD. In this study, we took the advantages of simultaneous PET/MRI and multivariate analyses to investigate the associations between AD-related stereotypical spatial patterns (topographies) of glucose metabolism, measured by fluorodeoxyglucose PET, and functional connectivity, measured by resting-state functional MRI. A total of 101 participants, including 37 patients with AD, 25 patients with mild cognitive impairment (MCI), and 39 cognitively normal controls, underwent PET/MRI scans and cognitive assessments. Three pairs of distinct but optimally correlated metabolic and functional topographies were identified, encompassing large-scale networks including the default-mode, executive and control, salience, attention, and subcortical networks. Importantly, the metabolic-functional associations were not only limited to one-to-one-corresponding regions, but also occur in remote and non-overlapping regions. Furthermore, both glucose metabolism and functional connectivity, as well as their linkages, exhibited various degrees of disruptions in patients with MCI and AD, and were correlated with cognitive decline. In conclusion, our results support distributed and heterogeneous topographic associations between metabolism and function, which are jeopardized by AD. Findings of this study may deepen our understanding of the pathological mechanism of AD through the perspectives of both local energy efficiency and long-term interactions between synaptic disruption and functional disconnection contributing to the clinical symptomatology in AD.