Vertebral metastases from neuroendocrine tumours: How to avoid false positives on 68Ga-DOTA-TOC PET using CT pattern analysis?

OBJECTIVES: To develop criteria to improve discrimination between vertebral metastases from neuroendocrine tumours (NETs) and benign bone lesions on PET combined with CT using DOTA-D-Phe1-Tyr3-octreotide labelled with gallium-68 (68Ga-DOTA-TOC). METHODS: In 535 NET patients, 68Ga-DOTA-TOC PET/CT examinations were reviewed retrospectively for vertebral CT lesions and/or PET foci. For each vertebral PET abnormality, appearance on CT, biological volume (BV), standardized uptake value (SUVmax) and ratios to those of reference organs were determined. All vertebral abnormalities were characterized as a metastasis, a typical vertebral haemangioma (VH) or other benign lesion. RESULTS: In 79 patients (14.8 %), we found 107 metastases, 34 VHs and 31 other benign lesions in the spine. The optimal cut-off values to differentiate metastases from benign lesions were BV ≥0.72 cm3, SUVmax ≥2, SUVmax ratio to a reference vertebra ≥2.1, to liver ≥0.28 and to spleen ≥0.14. They corresponded to lesion-based 68Ga-DOTA-TOC PET/CT sensitivity of 87 %, 98 %, 97 %, 99 % and 94 %, and specificity of 55 %, 100 %, 90 %, 97 %, 100 %, respectively. CONCLUSIONS: The high sensitivity of 68Ga-DOTA-TOC-PET/CT in detecting NET vertebral metastases was confirmed; this study showed that specificity could be improved by combining CT features and quantifying 68Ga-DOTA-TOC uptake. KEY POINTS: • Bone metastases in neuroendocrine tumours correlate with prognosis. • Benign bone lesions may mimic metastases on 68 Ga-DOTA-TOC PET/CT imaging. • The specific polka-dot CT pattern may be missing in some vertebral haemangiomas. • Lesion atypical for haemangiomas can be better characterized by quantifying 68 Ga-DOTA-TOC uptake.

¹8F-Fluorocholine PET/CT as a complementary tool in the follow-up of low-grade glioma: diagnostic accuracy and clinical utility.

PURPOSE: The follow-up of treated low-grade glioma (LGG) requires the evaluation of subtle clinical changes and MRI results. When the result is inconclusive, additional procedures are required to assist decision-making, such as the use of advanced MRI (aMRI) sequences and nuclear medicine scans (SPECT and PET). The aim of this study was to determine whether incorporating (18)F-fluorocholine PET/CT in the follow-up protocol for treated LGG improves diagnostic accuracy and clinical utility. METHODS: This was a prospective case-series study in patients with treated LGG during standard follow-up with indeterminate clinical and/or radiological findings of tumour activity. All patients underwent clinical evaluation, aMRI, (201)Tl-SPECT and (18)F-fluorocholine PET/CT. Images were interpreted by visual evaluation complemented with semiquantitative analysis. RESULTS: Between January 2012 and December 2013, 18 patients were included in this study. The final diagnosis was established by histology (five surgical specimens, one biopsy specimen) or by consensus of the Neuro-Oncology Group (11 patients) after a follow-up of >6 months (mean 14.9 ± 2.72 months). The global diagnostic accuracies were 90.9% for aMRI (38.8% inconclusive), 69.2 % for (201)Tl-SPECT (11.1% inconclusive), and 100% for (18)F-fluorocholine PET/CT. (201)Tl-SPECT led correctly to a change in the initial approach in 38.9% of patients but might have led to error in 27.8%. The use of (18)F-fluorocholine PET/CT alone rather than (201)Tl-SPECT led correctly to a change in the approach suggested by routine follow-up in 72.2% of patients and endorsed the approach in the remaining 27.8%. CONCLUSION: Our results support the need to complement structural MRI with aMRI and nuclear medicine procedures in selected patients. (18)F-Fluorocholine PET/CT can be useful in the individualized management of patients with treated LGG with uncertain clinical and/or radiological evidence of tumour activity.

Single Seminal Vesicle Metastasis From Dorsal Melanoma Detected by 18 F-FDG PET/CT and Confirmed by Biopsy.

ABSTRACT: This case shows an unusual presentation of a melanoma metastasis, visualized by 18 F-FDG digital PET/CT, with a single abnormal focal uptake in the right seminal vesicle. Histologic analysis confirmed a melanoma metastasis, subsequently treated by stereotactic radiation therapy. We illustrate an unusual and single-site millimetric melanoma metastasis detected by 18 F-FDG PET/CT, highlighting the high performance of state-of-the-art digital PET/CT and the importance of a multidisciplinary approach in treatment and follow-up of melanoma patients. In this case, histological diagnosis was essential for correct diagnosis and adequate clinical management of the patient.

Comparison of integrin αvß3 expression with 68Ga-NODAGA-RGD PET/CT and glucose metabolism with 18F-FDG PET/CT in esophageal or gastroesophageal junction cancers.

BACKGROUND: The primary aims of this study were to compare in patients with esophageal or esophagogastric junction cancers the potential of 68Ga-NODAGA-RGD PET/CT with that of 18F-FDG PET/CT regarding tumoral uptake and distribution, as well as histopathologic examination. METHODS: Ten 68Ga-NODAGA-RGD and ten 18F-FDG PET/CT were performed in nine prospectively included participants (1 woman; aged 58 ± 8.4 y, range 40-69 y). Maximum SUV (SUVmax) and metabolic tumor volumes (MTV) were calculated. The Mann-Whitney U test and Spearman correlation analysis (ρ) were used. RESULTS: 68Ga-NODAGA-RGD PET/CT detected positive uptake in 10 primary sites (8 for primary tumors and 2 for local relapse suspicion), 6 lymph nodes and 3 skeletal sites. 18F-FDG PET/CT detected positive uptake in the same sites but also in 16 additional lymph nodes and 1 adrenal gland. On a lesion-based analysis, SUVmax of 18F-FDG was significantly higher than those of 68Ga-NODAGA-RGD (4.9 [3.7-11.3] vs. 3.2 [2.6-4.2] g/mL, p = 0.014). Only one participant showed a higher SUVmax in an osseous metastasis with 68Ga-NODAGA-RGD as compared to 18F-FDG (6.6 vs. 3.9 g/mL). Correlation analysis showed positive correlation between 18F-FDG and 68Ga-NODAGA-RGD PET parameters (ρ = 0.56, p = 0.012 for SUVmax, ρ = 0.78, p < 0.001 for lesion-to-background ratios and ρ = 0.58, p = 0.024 for MTV). We observed that 18F-FDG uptake was homogenous inside all the confirmed primary sites (n = 9). In contrast, 68Ga-NODAGA-RGD PET showed more heterogenous uptake in 6 out of the 9 confirmed primary sites (67%), seen mostly in the periphery of the tumor in 5 out of the 9 confirmed primary sites (56%), and showed slight extensions into perilesional structures in 5 out of the 9 confirmed primary sites (56%). CONCLUSIONS: In conclusion, 68Ga-NODAGA-RGD has lower potential in the detection of esophageal or esophagogastric junction malignancies compared to 18F-FDG. However, the results suggest that PET imaging of integrin αvß3 expression may provide complementary information and could aid in tumor diversity and delineation. TRIAL REGISTRATION: Trial registration: NCT02666547. Registered January 28, 2016-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT02666547 .

Overview of the RGD-Based PET Agents Use in Patients With Cardiovascular Diseases: A Systematic Review.

Studies using arginine-glycine-aspartate (RGD)-PET agents in cardiovascular diseases have been recently published. The aim of this systematic review was to perform an updated, evidence-based summary about the role of RGD-based PET agents in patients with cardiovascular diseases to better address future research in this setting. Original articles within the field of interest reporting the role of RGD-based PET agents in patients with cardiovascular diseases were eligible for inclusion in this systematic review. A systematic literature search of PubMed/MEDLINE and Cochrane library databases was performed until October 26, 2021. Literature shows an increasing role of RGD-based PET agents in patients with cardiovascular diseases. Overall, two main topics emerged: the infarcted myocardium and atherosclerosis. The existing studies support that αvß3 integrin expression in the infarcted myocardium is well evident in RGD PET/CT scans. RGD-based PET radiotracers accumulate at the site of infarction as early as 3 days and seem to be peaking at 1-3 weeks post myocardial infarction before decreasing, but only 1 study assessed serial changes of myocardial RGD-based PET uptake after ischemic events. RGD-based PET uptake in large vessels showed correlation with CT plaque burden, and increased signal was found in patients with prior cardiovascular events. In human atherosclerotic carotid plaques, increased PET signal was observed in stenotic compared with non-stenotic areas based on MR or CT angiography data. Histopathological analysis found a co-localization between tracer accumulation and areas of αvß3 expression. Promising applications using RGD-based PET agents are emerging, such as prediction of remodeling processes in the infarcted myocardium or detection of active atherosclerosis, with potentially significant clinical impact.

Using CT Data to Improve the Quantitative Analysis of 18F-FBB PET Neuroimages.

18F-FBB PET is a neuroimaging modality that is been increasingly used to assess brain amyloid deposits in potential patients with Alzheimer's disease (AD). In this work, we analyze the usefulness of these data to distinguish between AD and non-AD patients. A dataset with 18F-FBB PET brain images from 94 subjects diagnosed with AD and other disorders was evaluated by means of multiple analyses based on t-test, ANOVA, Fisher Discriminant Analysis and Support Vector Machine (SVM) classification. In addition, we propose to calculate amyloid standardized uptake values (SUVs) using only gray-matter voxels, which can be estimated using Computed Tomography (CT) images. This approach allows assessing potential brain amyloid deposits along with the gray matter loss and takes advantage of the structural information provided by most of the scanners used for PET examination, which allow simultaneous PET and CT data acquisition. The results obtained in this work suggest that SUVs calculated according to the proposed method allow AD and non-AD subjects to be more accurately differentiated than using SUVs calculated with standard approaches.

[Findings of the (18)F-FDG PET-CT in a cardiac angiosarcoma complicated by a cardiac rupture]. / Hallazgos de la PET-TC con (18)F-FDG en un angiosarcoma cardíaco complicado con una rotura cardíaca.

Primary malignant tumors of the heart are a rare condition. The most common type is the cardiac angiosarcoma. The symptoms of this disease are very nonspecific and can be very difficult to diagnose by conventional imaging techniques. We report the case of a male patient with cardiac angiosarcoma who also had a rare complication, this being cardiac rupture, which required the use of (18)F-FDG PET-CT to demonstrate the mass malignancy and to reach a definitive diagnosis.