Diagnostic utility of positron emission tomography-computed tomography and indications for 18F-Fluorodeoxyglucose and amyloid-tracers

Positron emission tomography-computed tomography (PET-CT) is a nuclear medicine imaging technique widely used in oncology, cardiology and neurology where it'is becoming of great interest especially because of its role in the diagnosis and differential diagnosis between several pathological conditions involving the nervous system. In neurodegenerative diseases, the most used PET-CT radiopharmaceuticals are 18Fluoro-Fluorodeoxyglucose (18FFDG), a glucose analogue that is able to identify abnormalities of cerebral glucose metabolism, and amyloid-tracers (11C-PiB, 18F-Florbetapir, 18F-Flutemetamol, 18F-Florbetaben) that are able to detect presence of amyloid plaques. Depending on the specific characteristic of tracers and patient's disease, the examination has dedicated appropriate indications that are illustrated in this article. PET-CT, with its several tracers, is an accurate tool in evaluating neurodegenerative diseases. 18F-FDG is considered a hallmark of the stage of the disease. Glucose hypometabolism in specific cerebral areas allows distinguishing different degenerative diseases. Amyloid tracers are considered the hallmark of the state of the disease. The uptake of PET-amyloids tracers reflects the cortical regional density of amyloid plaques

Prevalence of symptomatic and silent stress-induced perfusion defects in diabetic patients with suspected coronary artery disease referred for myocardial perfusion scintigraphy

Purpose: Silent myocardial ischaemia—as evaluated by stress-induced perfusion defects on myocardial perfusion scintigraphy (MPS) in patients without a history of chest pain—is frequent in diabetes and is associated with increased rates of cardiovascular events. Its prevalence has been determined in asymptomatic diabetic patients, but remains largely unknown in diabetic patients with suspected coronary artery disease (CAD) in the clinical setting. In this study we therefore sought (a) to determine the prevalence of symptomatic and silent perfusion defects in diabetic patients with suspected CAD and (b) to characterise the eventual predictors of abnormal perfusion. Methods: The patient population comprised 133 consecutive diabetic patients with suspected CAD who had been referred for MPS. Studies were performed with exercise (41%) or pharmacological stress testing (1-day protocol, 99mTc-sestamibi, 201Tl or both). We used semi-quantitative analysis (20-segment polar maps) to derive the summed stress score (SSS) and the summed difference score (SDS). Results: Abnormal MPS (SSS≥4) was observed in 49 (37%) patients (SSS=4.9±8.4, SDS=2.4±4.7), reversible perfusion defects (SDS≥2) in 40 (30%) patients [SSS=13.3±10.9; SDS=8.0±5.6; 20% moderate to severe (SDS>4), 7% multivessel] and fixed defects in 21 (16%) patients. Results were comparable between patients with and patients without a history of chest pain. Of 75 patients without a history of chest pain, 23 (31%, 95% CI=21-42%) presented reversible defects (SSS=13.9±11.3; SDS=7.4±1.2), indicative of silent ischaemia. Reversible defects were associated with inducible ST segment depression during MPS stress [odds ratio (OR)=3.2, p<0.01). Fixed defects were associated with erectile dysfunction in males (OR=3.7, p=0.02) and lower aspirin use (OR=0.25, p=0.02). Conclusion: Silent stress-induced perfusion defects occurred in 31% of the patients, a rate similar to that in patients with a history of chest pain. MPS could identify these patients with a potentially increased risk of cardiovascular event

3-Methoxy-Phencyclidine Induced Psychotic Disorder: A Literature Review and an 18 F-FDG PET/CT Case Report

© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/New Psychoactive Substances (NPS) are modifying the drug scenario worldwide and have become a public health concern because of their toxicological profiles and their harmful physical/psychological effects. 3-Methoxy-Phencyclidine (3-MeO-PCP), a non-competitive antagonist of glutamate N-methyl-D-aspartate (NMDA) receptors, belongs to the phencyclidine-like subfamily of arylcyclohexylamines and has gained attention for its toxic, sometimes fatal, effects. Despite several cases of intoxication and death reported in the literature, little is known about substance-induced psychotic disorders (SIP) and potential cognitive impairment following 3-MeO-PCP intake. This literature review aimed to summarize available evidence about 3-MeO-PCP mechanisms of action and physical and psychotropic effects and to spread preliminary findings about persistent psychotic symptoms and impaired cognitive functioning. Additionally, the case of an SIP is reported in a 29-year-old man with small oral intakes of 3-MeO-PCP over two weeks until a high dose ingestion. Psychometric and neuropsychological assessment and brain [18F]-fluorodeoxyglucose positron emission tomography integrated with computed tomography were used to support clinical description. Identifying and addressing the characteristic clinical features and neural substrates of NPS-induced psychoses might help clinicians with a more precise differentiation from other psychotic disorders. Although further studies are required, phenotyping the cognitive profile of NPS users might provide targets for tailored therapeutic approaches.Peer reviewe

Occult lung infarction may induce false interpretation of 18F-FDG PET in primary staging of pulmonary malignancies

Purpose: The aim of the present report is to describe abnormal 18F-fluorodeoxyglucose (FDG) accumulation patterns in the pleura and lung parenchyma in a group of lung cancer patients in whom lung infarction was present at the time of positron emission tomography (PET). Methods: Between November 2002 and December 2003, a total of 145 patients (102 males, 43 females; age range 38-85years) were subjected to whole-body FDG PET for initial staging (n=117) or restaging (n=11) of lung cancer or for evaluation of solitary pulmonary nodules (n=17). Of these patients, 24 displayed abnormal FDG accumulation in the lung parenchyma that was not consistent with the primary lesion under investigation (ipsilateral n=12, contralateral n=9 or bilateral n=3). Without correlative imaging, this additional FDG uptake would have been considered indeterminate in differential diagnosis. Results: Of the 24 patients who were identified as having such lesions, six harboured secondary tumour nodules diagnosed as metastases, while in three the diagnosis of a synchronous second primary lung tumour was established. Additionally, nine patients were identified as having post-stenotic pneumonia and/or atelectasis (n=6) or granulomatous lung disease (n=3). In the remaining six (4% of all patients), a diagnosis of recent pulmonary embolism that topographically matched the additional FDG accumulation (SUVmax range 1.4-8.6, mean 3.9) was made. Four of these six patients were known to have pulmonary embolism, and hence false positive interpretation was avoided by correlating the PET findings with those of the pre-existing diagnostic work-up. The remaining two patients were harbouring small occult infarctions that mimicked satellite nodules in the lung periphery. Based on histopathological results, the abnormal FDG accumulation in these two patients was attributed to the inflammatory reaction and tissue repair associated with the pathological cascade of pulmonary embolism. Conclusion: In patients with pulmonary malignancies, synchronous lung infarction may induce pathological FDG accumulation that can mimic active tumour manifestations. Identifying this potential pitfall may allow avoidance of false positive FDG PET interpretatio

The Prognostic Value of 18^{18}F-FDG PET Imaging at Staging in Patients with Malignant Pleural Mesothelioma: A Literature Review

Malignant pleural mesothelioma (MPM) is an aggressive malignancy, frequently diagnosed at locally-advanced/metastatic stages. Due to a very poor prognosis and limited treatment options, the need to identify new prognostic markers represents a great clinical challenge. The prognostic role of metabolic information derived from Positron Emission Tomography (PET) with $^{18}$F-Fluoro-deoxy-glucose ($^{18}$F-FDG) has been investigated in different MPM settings, however with no definitive consensus. In this comprehensive review, the prognostic value of FDG-PET imaging exclusively performed at staging in MPM patients was evaluated, conducting a literature search on PubMed/MEDLINE from 2010 to 2020. From the 19 selected studies, despite heterogeneity in several aspects, staging FDG-PET imaging emerges as a valuable prognostic biomarker, with higher tumor uptake predictive of worse prognosis, and with volumetric metabolic parameters like Metabolic Tumor Volume, (MTV) and Total Lesion Glycolisis (TLG) performing better than SUVmax. However, PET uptake parameters were not always confirmed as independent prognostic factors, especially in patients previously treated with pleurodesis and with a non-epithelioid histotype. Future prospective studies in larger and clinically homogeneous populations, and using more standardized methods of PET images analysis, are needed to further validate the value of staging FDG-PET in the prognostic MPM stratification, with a potential impact on better patient-tailored treatment planning, in the perspective of personalized medicine

Correction to: The role of molecular imaging in the frame of the revised dementia with Lewy body criteria

In the article mentioned above all authors were assigned affiliation 14, which is wrong. Affiliation 14 belongs only to author Agostino Chiaravalloti

Application of Artificial Neural Network to Preoperative 18F-FDG PET/CT for Predicting Pathological Nodal Involvement in Non-small-cell Lung Cancer Patients

Purpose: To evaluate the performance of artificial neural networks (aNN) applied to preoperative 18F-FDG PET/CT for predicting nodal involvement in non-small-cell lung cancer (NSCLC) patients. Methods: We retrospectively analyzed data from 540 clinically resectable NSCLC patients (333 M; 67.4 \ub1 9 years) undergone preoperative 18F-FDG PET/CT and pulmonary resection with hilo-mediastinal lymphadenectomy. A 3-layers NN model was applied (dataset randomly splitted into 2/3 training and 1/3 testing). Using histopathological reference standard, NN performance for nodal involvement (N0/N+ patient) was calculated by ROC analysis in terms of: area under the curve (AUC), accuracy (ACC), sensitivity (SE), specificity (SP), positive and negative predictive values (PPV, NPV). Diagnostic performance of PET visual analysis (N+ patient: at least one node with uptake mediastinal blood-pool) and of logistic regression (LR) was evaluated. Results: Histology proved 108/540 (20%) nodal-metastatic patients. Among all collected data, relevant features selected as input parameters were: patients\u2019 age, tumor parameters (size, PET visual and semiquantitative features, histotype, grading), PET visual nodal result (patient-based, as N0/N+ and N0/N1/N2). Training and testing NN performance (AUC = 0.849, 0.769): ACC = 80 and 77%; SE = 72 and 58%; SP = 81 and 81%; PPV = 50 and 44%; NPV = 92 and 89%, respectively. Visual PET performance: ACC = 82%, SE = 32%, SP = 94%; PPV = 57%, NPV = 85%. Training and testing LR performance (AUC = 0.795, 0.763): ACC = 75 and 77%; SE = 68 and 55%; SP = 77 and 82%; PPV = 43 and 43%; NPV = 90 and 88%, respectively..Conclusions: aNN application to preoperative 18F-FDG PET/CT provides overall good performance for predicting nodal involvement in NSCLC patients candidate to surgery, especially for ruling out nodal metastases, being NPV the best diagnostic result; a high NPV was also reached by PET qualitative assessment. Moreover, in such population with low a priori nodal involvement probability, aNN better identify the relatively few and unexpected nodal-metastatic patients than PET analysis, so supporting the additional aNN use in case of PET-negative images

DWI-MR and PET-CT Functional Imaging for Boost Tumor Volume Delineation in Neoadjuvant Rectal Cancer Treatment

BACKGROUND/AIM T2 weighted magnetic resonance (MR) imaging is the gold standard for locally advanced rectal cancer (LARC) staging. The potential benefit of functional imaging, as diffusion-weighted MR (DWI) and positron emission tomography-computed tomography (PET-CT), could be considered for treatment intensification strategies. Dose intensification resulted in better pathological complete response (pCR) rates. This study evaluated the inter-observer agreement between two radiation oncologists, and the difference in gross tumor volume (GTV) delineation in simulation-CT, T2-MR, DWI-MR, and PET-CT in patients with LARC. PATIENTS AND METHODS Two radiation oncologists prospectively delineated GTVs of 24 patients on simul-CT (CT$_{GTV}$), T2-weighted MR (T2$_{GTV}$), echo planar b1000 DWI (DWI$_{GTV}$) and PET-CT (PET$_{GTV}$). Observers' agreement was assessed using Dice index. Kruskal-Wallis test assessed differences between methods. RESULTS Mean CT$_{GTV}$, T2$_{GTV}$, DWI$_{GTV}$, and PET$_{GTV}$ were 41.3±26.9 cc, 25.9±15.2 cc, 21±14.8 cc, and 37.7±27.7 cc for the first observer, and 42.2±27.9 cc, 27.6±16.9 cc, 19.9±14.9cc, and 34.8±24.3 cc for the second observer, respectively. Mean Dice index was 0.85 for CT$_{GTV}$, 0.84 for T2$_{GTV}$, 0.82 for DWI$_{GTV}$, and 0.89 for PET$_{GTV}$, representative of almost perfect agreement. Kruskal-Wallis test showed a statistically significant difference between methods (p=0.009). Dunn test showed there were differences between DWI$_{GTV}$ vs. PET$_{GTV}$ (p=0.040) and DWI$_{GTV}$ vs. CT$_{GTV}$ (p=0.008). CONCLUSION DWI resulted in smaller volume delineation compared to CT, T2-MR, and PET-CT functional images. Almost perfect agreements were reported for each imaging modality between two observers. DWI-MR seems to remain the optimal strategy for boost volume delineation for dose escalation in patients with LARC

Prevalence of spinocellulart ataxia type 2 mutation among ittalian Parkinsonian patients

We evaluated the prevalence of the SCA2 mutation among 224 Italian patients affected by typical Parkinsonism, including 145 sporadic and 79 familial forms. Pink1, Parkin, and LRRK2 gene mutations had been excluded previously. Molecular testing for the CAG expansion at the SCA 2 locus was performed on leukocyte DNA. Cloning and sequencing of the expanded allele was performed in patients positive for the SCA2 expansion. A 38 CAG expansion was detected in 1 of 79 families studied. The proband, a male age 67, and his sister, age 69, were both affected by a benign form of L-dopa–responsive Parkinsonism not associated with cerebellar signs. The inheritance was autosomal dominant. The CAG expansion was stable through meiotic transmission: sequence analysis showed that the CAG stretch was interrupted by 3 CAA. Our study shows that CAG expansion at the SCA 2 locus may represent a genetic cause of familial L-dopa–responsive Parkinsonism among Italian patients. The stability of the pathological CAG expansion detected in this family was related to the presence of CAA interruptions. These findings, together with literature data, suggest that the molecular intrinsic structure of the expanded allele may modulate the phenotypic expression of the SCA2 mutatio

Interim FDG-PET/CT in Hodgkin lymphoma: the prognostic role of the ratio between target lesion and liver SUVmax (rPET).

OBJECTIVE: To evaluate the prognostic role of the ratio between target lesion and liver SUVmax (rPET) in patients with Hodgkin lymphoma (HL) undergoing interim FDG-PET/CT and to compare rPET with the 5-point Deauville Score (5p-DS). METHODS: Sixty-eight patients with HL undergoing interim FDG-PET/CT after first courses of chemotherapy were evaluated. The receiver operating characteristic (ROC) approach was applied to identify the optimal cutpoint of rPET with respect to progression free survival (PFS). The prognostic significance of rPET was compared with 5p-DS (scores 4 and 5 considered as positive). Positive predictive value (PPV) and negative predictive value (NPV) were calculated using the presence of an adverse event as the gold standard. RESULTS: The ROC analysis for rPET as a predictor of progression showed an optimal rPET cutpoint of 1.14. Both 5p-DS and rPET were strong outcome predictors (p &lt; 0.001). Patients with negative 5p-DS and patients with rPET &lt;1.14 had a similar two-year PFS (86 and 87 %, respectively). Patients with a positive 5p-DS had a 2-year PFS of 27 %, while patients with rPET &gt;1.14 had a 2-year PFS of 15 %. 5p-DS and rPET cutoff of 1.14 showed a PPV of 58 versus 70 %, and a NPV of 85 versus 86 %, respectively. CONCLUSIONS: rPET could be considered an accurate prognostic factor in patients with HL undergoing interim FDG-PET/CT. Larger prospective studies are needed to confirm these data