the Quarterly Journal of Nuclear Medicine and Molecular Imaging最新文献

Positron-emission tomography magnetic resonance imaging (PET/MRI) has emerged as a powerful hybrid molecular imaging technique in clinical practice, overcoming initial technical challenges to provide comprehensive anatomic and metabolic information. This advanced modality combines the superior soft tissue contrast of MRI with the metabolic insights of PET, offering advantages in hepatobiliary imaging, including improved detection of small liver metastases and reduced radiation exposure. The evolution of PET/MRI technology has been marked by significant advancements, such as the development of MRI-compatible PET detectors and sophisticated motion compensation techniques. These innovations have enhanced image quality and co-registration accuracy, crucial for hepatobiliary imaging. The integration of time-of-flight capability and silicon photomultipliers has further improved spatial resolution and sensitivity. PET/MRI protocols for liver imaging typically involve a whole-body scan followed by a targeted liver examination, utilizing radiotracers like FDG and DOTATATE. This approach allows for comprehensive staging and detailed liver assessment in a single session, potentially altering management decisions in up to 30% of patients with intrahepatic cholangiocarcinoma. While PET/MRI excels in characterizing various hepatobiliary lesions, including hepatocellular carcinoma and cholangiocarcinoma, challenges remain in differentiating certain benign entities like small hemangiomas from metastases. Ongoing research and clinical experience continue to refine the role of PET/MRI in hepatobiliary imaging, promising improved diagnostic accuracy and patient care.

Hepatobiliary scintigraphy with single-photon emission computed tomography (SPECT) is an essential Nuclear Medicine exam for assessing hepatobiliary abnormalities and planning therapy. We aim to offer a thorough and all-encompassing analysis of hepatobiliary imaging with SPECT to emphasize the practicality, precision in diagnosis, surgical or transplant planning, and advanced uses of SPECT/CT in assessing hepatobiliary disease. Readers can anticipate acquiring a comprehensive understanding of the subsequent facets. The manuscript will explore in detail the diverse clinical uses of SPECT/CT imaging in hepatobiliary system, recent technological breakthroughs in SPECT/CT imaging techniques, specifically addressing quantitative analysis methodologies, and the integration of SPECT/CT with other imaging modalities. This article will provide readers with information on current research trends and future prospects in SPECT/CT imaging for hepatobiliary applications, such as strategies for monitoring therapy, the use of artificial intelligence and machine learning for quantitative imaging biomarkers, how these advanced techniques influence patient care, treatment choices, and prognostic predictions. The goal of the review is to help the readers acquire useful knowledge about the latest hepatobiliary SPECT/CT imaging, their clinical applications, and their prospective contribution to the advancement.

Background: Arterial spin labeling (ASL) MRI has been anecdotally used to assess brain perfusion in autoimmune encephalitis (AE) and its relationship with [¹⁸F]FDG-PET dysmetabolism has been scarcely investigated.Considering the physiological coupling of metabolism and perfusion, we aimed to evaluate the degree of correspondence between ASL-MRI and [¹⁸F]FDG-PET in AE.

Methods: A retrospective cohort of five patients underwent ASL-MRI and [¹⁸F]FDG-PET during the acute stage and at follow-up. We assessed the presence of regions with hypermetabolism on [¹⁸F]FDG-PET and hyperperfusion on ASL-MRI and evaluated concordance and spatial overlap of these metrics. Clinical assessment scale in AE and modified Rankin Scale were obtained at baseline and follow-up.

Results: In two patients [¹⁸F]FDG-PET and ASL-MRI were unremarkable; in three patients there were anatomically overlapping areas of hypermetabolism and hyperperfusion (average DICE similarity coefficient 0.358). Following immunotherapy, metabolic and perfusion changes consistently demonstrated a progressive normalization, aligning with clinical improvement.

Conclusions: We identified suboptimal anatomical correspondence of abnormalities assessed with [¹⁸F]FDG-PET and ASL-MRI. Hyperperfusion and hypermetabolism might reflect differently AE-related pathophysiological correlates, but they both demonstrate ability to monitor disease activity. ASL-MRI is a promising marker of disease activity in AE and a favorable alternative to [¹⁸F]FDG-PET due to its cost-effectiveness, safety, and wide availability.

Background: The diagnostic utility of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) compared to bone marrow biopsy (BMB) in patients with non-Hodgkin lymphoma (NHL) remained to be confirmed. This study aimed to compare BMB and PET/CT for bone marrow infiltration (BMI) in patients with NHL.

Methods: PubMed, Embase, and the Cochrane library were searched for papers published up to October 2021. The outcomes were the true positive and negative and false positive and negative rates for BMB and PET/CT. The summarized sensitivity, specificity, positive likelihood ratios (PLR), negative likelihood ratios (NLR), and diagnostic odds ratios (DOR) were calculated.

Results: Thirteen studies with a total of 2396 patients were included. Significant differences are observed between BMB and PET/CT for sensitivity (relative ratio: 0.749; 95% CI: 0.586-0.956; P=0.020) and NLR (relative ratio: 1.839; 95% CI: 1.106-3.058; P=0.019), but not for specificity (P=0.819), PLR (P=0.802), and DOR (P=0.150). The summary area under the receiver operating characteristic curves for BMB is 0.692 (SE: 0.170) and 0.977 (SE: 0.021) for PET/CT.

Conclusions: PET/CT presents a better sensitivity and NLR for the detection of BMI in patients with NHL, whereas no differences are found regarding specificity, PLR, and DOR compared with BMB.

Introduction: Few therapeutic options are currently available for refractory meningiomas. Encouraging results have been reported for ¹⁷⁷Lu-labeled somatostatin receptor-targeted radiopeptide therapy (SSTR-RT). The current therapeutic scheme is based on the fixed doses that are recommended for neuroendocrine tumor treatment. However, in personalized medicine, tumor dosimetry can be determined from repeat ¹⁷⁷Lu scintigraphy. The aim of this review was to report on the methods used for calculating the tumor absorbed dose (AD) in meningioma patients treated with ¹⁷⁷Lu-SSTR-RT and their values.

Evidence acquisition: The search was performed in Medline, Embase and the Cochrane Library until March 1^st, 2024 to retrieve papers related to the topic. The following terms were used for searching: (meningioma) AND ((sstr) OR (receptors somatostatin) OR (somatostatin) OR (octreotide)) AND ((PRRT) OR (radionuclide therapy) OR (dotatate) OR (dotatoc) OR (177Lu-DOTATOC) OR (177Lu-DOTATATE) OR (radiopeptide)).

Evidence synthesis: Seven articles (including 46 patients and 108 cycles of treatment) reporting on tumor AD during ¹⁷⁷Lu-SSTR-RT were included in the analysis. The methods of acquisition, reconstruction parameters and postimage processing to determine tumor AD were very heterogeneous among the studies. The meningioma AD associated with the agonist ¹⁷⁷Lu-SSTR-RT reported in the majority of studies ranged from 0.1-1.5 Gy/GBq, which was lower than that reported for neuroendocrine tumors (1.3-22.9 Gy/GBq).

Conclusions: The tumor AD that was reported during treatment with ¹⁷⁷Lu-SSTR-RT in refractory meningioma patients is generally low. Harmonization of the methodology for dosimetry calculations is needed to compare the different reported values and optimize treatment at the individual level.

Background: Amino-acid (AA) PET has recently been endorsed by the ESTRO-EANO guidelines for RT-planning in glioblastomas, with recommended lesion-to-brain-ratio thresholds (1.6-1.8) derived from a biopsy-controlled FET-PET study. We aimed to compare target definition at [¹⁸F]DOPA-PET between the ESTRO-EANO thresholds and other biological-tumor-volume (BTV) thresholds (derived from the striatum) typically used in [¹⁸F]DOPA-PET.

Methods: A retrospective analysis was conducted on glioma patients scanned with [¹⁸F]DOPA-PET/CT at our center between April 2021 and January 2024. 3D BTV was semi-automatically computed using a dedicated workstation (Philips HealthCare) with four thresholds: 1.6xSUVmean of background, 1.8xSUVmean of background, SUVmean and SUVmax of the contralateral striatum. The delineation accuracy of different thresholds was visually evaluated and a t-test was used to compare the different VOIs volumes (0.05 significance-level).

Results: 50 patients were included (36 previously received surgery). Volume definition based on the striatum SUVmax was significantly smaller compared to other thresholds (2.1 cm³), resulting in inaccurate VOIs at visual inspection in 21/50 patients. No significant differences were highlighted in BTV defined based on 1.6 or 1.8xSUVmean of background (15.7 vs. 12.7 cm³; VOIs accurate in 49/50 and 46/50 patients, respectively). BTV based on striatum SUVmean was significantly smaller compared to the 1.6xSUVmean threshold only in surgically-treated patients (P=0.04), while no significant differences were highlighted compared to the 1.8xSUVmean threshold regardless of the patients' group.

Conclusions: The ESTRO-EANO FET-PET thresholds proved to be interchangeable in patients scanned with [¹⁸F]DOPA-PET, while the use of a threshold based on the contralateral-striatum SUVmean provided partially overlapping results prompting further investigation.

Background: The pathophysiology of normal pressure hydrocephalus (NPH) has not been fully elucidated. Treating NPH with cerebrospinal fluid shunts to improve gait disturbances may have some risks and inconsistent benefits. No clear predictive factor has been identified thus far. This preliminary study aimed to evaluate the predictive value of preoperative brain ¹⁸F-FDG positron emission tomography (PET) on overall gait response in patients with NPH.

Methods: Sixteen patients with NPH who underwent ¹⁸F-FDG PET before shunt surgery between 2012 and 2022 were included retrospectively and separated into two groups based on their gait response one year after surgery: responders (R) or nonresponders (NR). Brain glucose metabolism was assessed using visual and semiquantitative analyses using SPM8 software (Welcome Department of Cognitive Neurology, University College, London, UK). Five regions of interest were selected: global cortex, cerebellum, thalamus, striatum, and midbrain.

Results: Visual interpretation showed more frequent hypometabolism of the striatum, thalamus and global cortex in NR. None of the patients showing hypometabolism of these regions were R. Based on these results, the visual interpretation allowed us to identify 3/8 NR and 8/8 R. Semiquantitative analysis confirmed significantly lower thalamic metabolism in the NR group (P=0.037) and a trend towards lower metabolism of the striatum (P=0.075) with an area under the curve of 0.77 for thalamic metabolism to discriminate between R and NR.

Conclusions: This preliminary study using brain ¹⁸F-FDG PET suggests that reduced brain metabolism in the thalamus and striatum along with cortical hypometabolism may be associated with poorer gait response to CSF shunting in normal pressure hydrocephalus (NPH). Although these findings suggest that preoperative brain 18F-FDG PET could potentially aid in selecting appropriate candidates for shunt surgery, further research with larger sample sizes is needed to confirm these results.

Introduction: Metabolic connectivity has been studied in various neurodegenerative diseases, particularly Alzheimer's disease (AD), but there is a wealth of accumulated evidence and sometimes conflicting results, depending on the methodology applied. Therefore, the aim of this systematic review was to summarize the results obtained regarding metabolic brain connectivity using [¹⁸F]-FDG-PET in AD patients compared to cognitively normal subjects.

Evidence acquisition: A systematic and exhaustive search of data available in the literature was carried out by querying the PubMed and Web of Science databases. Studies had to meet the following criteria: 1) a metabolic connectivity study with [¹⁸F]-FDG-PET in AD patients; 2) the inclusion of a control group of healthy subjects or cognitively normal controls; and 3) use of seed-based, independent/principal component analyses or methods derived from graph theory. This systematic review followed the PRISMA method.

Evidence synthesis: A total of 49 full-text publications were included, involving 3589 AD patients, 3272 prodromal AD patients and 3898 cognitively normal subjects. These results show that AD patients have a reorganization of metabolic connectivity on a global scale, with a decrease in or even the loss of networks seen in the healthy brain and an increase in more local, less efficient connectivity. This reorganization affects not only areas commonly affected in AD but also remote regions known to be usually spared in this pathology.

Conclusions: Changes in metabolic connectivity in AD patients do not simply constitute a decrease in global connectivity but rather more complex local and global changes ultimately affecting all brain regions.

Background: Cognitive reserve (CR) is an expression of brain resilience in response to damage. Education, occupational experience and leisure activities are thought to increase CR and have beneficial effects on global cognition and cognitive decline in Parkinson's disease (PD). We aimed to disclose brain metabolic and dopaminergic correlates of CR in de-novo PD patients.

Methods: Sixty-two drug-naïve de-novo PD patients underwent [¹⁸F]FDG-PET and DAT-SPECT. CR was quantified through the Cognitive-Reserve-Index questionnaire including total-CR and 3 subscores (educational-CR, occupational-CR, leisure-CR). Specific binding ratios (SBRs) and Z-scores in basal ganglia were obtained with 'BasGan-V2'. Z-scores were used as dependent variables in general linear models to assess the interaction between dopaminergic function and CR. Voxel-based correlation between brain metabolism and CR-scores and between SBR and [¹⁸F]FDG-PET was evaluated using SPM12 (P<0.05 FWE-corrected at peak and cluster level considered significant).

Results: Dopaminergic deficit in the most affected hemisphere (MAH) putamen was significantly less marked in higher CR patients (Z-score -1.7±0.1 highly-educated versus -2.1±0.1 poorly-educated, P<0.02). Total and leisure-related-CR resulted correlated directly with z-scores of the MAH putamen (P<0.018 and P<0.003) and inversely with brain metabolism in both cerebellar hemispheres (P<0.001). MAH-putamen SBR correlated directly with metabolism in occipital and parietal cortex (P<0.003) and inversely in cerebellar hemispheres (P<0.02).

Conclusions: CR proxies demonstrated to correlate directly with dopaminergic function and inversely with metabolism in cerebellar hemispheres in de-novo PD patients. The present multi-modal approach including both metabolic and dopaminergic correlates of CR allowed to identify possible compensation mechanisms, highlighting a potential role of the cerebellum that deserves further investigation.