Long-axial field-of-view PET/CT for the assessment of inflammation in calcified coronary artery plaques with [68 Ga]Ga-DOTA-TOC.

PURPOSE: Inflamed, prone-to-rupture coronary plaques are an important cause of myocardial infarction and their early identification is crucial. Atherosclerotic plaques are characterized by overexpression of the type-2 somatostatin receptor (SST2) in activated macrophages. SST2 ligand imaging (e.g. with [68 Ga]Ga-DOTA-TOC) has shown promise in detecting and quantifying the inflammatory activity within atherosclerotic plaques. However, the sensitivity of standard axial field of view (SAFOV) PET scanners may be suboptimal for imaging coronary arteries. Long-axial field of view (LAFOV) PET/CT scanners may help overcome this limitation. We aim to assess the ability of [68 Ga]Ga-DOTA-TOC LAFOV-PET/CT in detecting calcified, SST2 overexpressing coronary artery plaques. METHODS: In this retrospective study, 108 oncological patients underwent [68 Ga]Ga-DOTA-TOC PET/CT on a LAFOV system. [68 Ga]Ga-DOTA-TOC uptake and calcifications in the coronary arteries were evaluated visually and semi-quantitatively. Data on patients' cardiac risk factors and coronary artery calcium score were also collected. Patients were followed up for 21.5 ± 3.4 months. RESULTS: A total of 66 patients (61.1%) presented with calcified coronary artery plaques. Of these, 32 patients had increased [68 Ga]Ga-DOTA-TOC uptake in at least one coronary vessel (TBR: 1.65 ± 0.53). Patients with single-vessel calcifications showed statistically significantly lower uptake (SUVmax 1.10 ± 0.28) compared to patients with two- (SUVmax 1.31 ± 0.29, p < 0.01) or three-vessel calcifications (SUVmax 1.24 ± 0.33, p < 0.01). There was a correlation between coronary artery calcium score (CACS) and [68 Ga]Ga-DOTA-TOC uptake, especially in the LAD (p = 0.02). Stroke and all-cause death occurred more frequently in patients with increased [68 Ga]Ga-DOTA-TOC uptake (15.63% vs. 0%; p:0.001 and 21.88% vs. 6.58%; p: 0.04, respectively) during the follow-up period. CONCLUSION: [68 Ga]Ga-DOTA-TOC as a marker for the macrophage activity can reveal unknown cases of inflamed calcified coronary artery plaques using a LAFOV PET system. [68 Ga]Ga-DOTA-TOC uptake increased with the degree of calcification and correlated with higher risk of stroke and all-cause death. [68 Ga]Ga-DOTA-TOC LAFOV PET/CT may be useful to assess patients' cardiovascular risk.

New thresholds in semi-quantitative [18F]FDG PET/CT are needed to assess large vessel vasculitis with long-axial field-of-view scanners.

AIM: [18F]FDG PET/CT proved accurate in the diagnostic work-up of large vessel vasculitis (LVV). While a visual interpretation is currently considered adequate, several attempts have been made to integrate it with a semiquantitative evaluation. In this regard, there is the need to validate current or new thresholds for the semiquantitative parameters on long-axial field of view (LAFOV) scanners. METHODS: We retrospectively evaluated 100 patients (50 with LVV and 50 controls) who underwent [18F]FDG LAFOV PET/CT. Semiquantitative parameters (SUVmax and SUVmean) were calculated for large vessels in 3 districts (supra-aortic [SA], thoracic aorta [TA], and infra-aortic [IA]). Values were also normalized to liver activity (SUVmax/L-SUVmax, and SUVmax/L-SUVmean). RESULTS: Of the 50 patients diagnosed with LVV, SA vessels were affected in 38 (76%), TA in 42 (84%) and IA vessels in 26 (52%). To-liver normalized values had higher diagnostic accuracy than non-normalized values (AUC always ≥ 0.90 vs. 0.74-0.89). For the SA vessels, best thresholds were 0.66 for SUVmax/L-SUVmax and 0.88 for SUVmax/L-SUVmean; for the TA, 1.0 for SUVmax/L-SUVmax and 1.30 for SUVmax/L-SUVmean; finally, for IA vessels, the best threshold was 0.83 for SUVmax/L-SUVmax and 1.11 for SUVmax/L-SUVmean. CONCLUSION: LAFOV [18F]FDG-PET/CT is accurate in the diagnostic workup of LVV, but different threshold in semi-quantitative parameters than reported in literature for standard scanners should be considered.

Diagnostic value of FDG-PET/CT in the diagnostic work-up of inflammation of unknown origin.

Introduction The present study aims to evaluate the clinical diagnostic value of FDG-PET/CT in patients with inflammation of unknown origin. Material and methods We retrospectively analyzed data of 130 patients who presented general inflammatory symptoms and/or elevated level of CRP and underwent FDG-PET/CT for the purpose of identifying unknown foci of inflammation. The accuracy of PET/CT findings was assessed against the standard of eventual clinical diagnosis e.g. results of pathology, microbiology or other imaging methods. Results In 99/130 patients (76 %) a final diagnosis was established, FDG-PET/CT showed a sensitivity and specificity of each 93 %. A decreased pseudocholinesterase is associated with a higher SUVmax value and with a higher CRP value whereas no significant relationship was found between elevated CRP values and the SUVmax, although higher CRP values are associated significantly with a true positive PET/CT result. Conclusion FDG-PET/CT is a highly sensitive, specific and accurate method for the detection of foci of inflammation of unknown origin. The combination of decreased pseudocholinesterase and increased CRP levels may be a useful tool to select patients for FDG PET/CT.

Life after thyroid cancer: the role of thyroglobulin and thyroglobulin antibodies for postoperative follow-up.

INTRODUCTION: Differentiated thyroid carcinomas (DTCs) are treated with (near-)total thyroidectomy and radioiodine therapy. Recently, the use of highly sensitive thyroglobulin (hsTg) assays has simplified DTC follow-up and improved patients' quality of life. More limited approaches are currently applied in low-risk patients requiring interpretations of Tg results in different clinical scenarios. Finally, Tg assays are hampered by interference from thyroglobulin autoantibodies (TgAb). AREAS COVERED: The role of Tg measurement in DTC patients treated with complete thyroid ablation, thyroidectomy alone, or lobectomy is summarized. The management of patients carrying positive TgAb is also addressed. EXPERT OPINION: Patients with undetectable hsTg after total thyroid ablation are safely managed by periodic hsTg measurement, combined with selective use of imaging procedures in few cases. Serum hsTg trend remains informative in patients treated without radioiodine ablation. However, reliable reference values are urgently needed in this setting. The role of hsTg is debated in patients who have undergone lobectomy due to the amount of Tg released by a functioning thyroid lobe. The evaluation of TgAb trend over time (i.e. surrogate tumor marker) is recommended in patients with positive TgAb and potentially interfering Tg results.

Unexpected 99mTcO4- Uptake by Lung Adenocarcinoma.

ABSTRACT: A 76-year-old woman underwent 99mTcO4- thyroid scintigraphy to clarify thyrotoxicosis. In addition to suppressed thyroid uptake, an atypical tracer accumulation appeared on already know pulmonary adenocarcinoma in the left lung upper lobe. Surgical pathology was reviewed confirming the diagnosis of lung adenocarcinoma with focal mucins production and excluding a misdiagnosed differentiated thyroid carcinoma metastasis.

Different Formulations of Levothyroxine for Treating Hypothyroidism: A Real-Life Study.

OBJECTIVE: Hypothyroid patients are treated by sodium levothyroxine (LT4). Tablet is the mostly used LT4 formulation, and the fasting regimen is required for the absorption of active principle. Also, gastrointestinal diseases and drugs may impair the LT4 bioavailability when tablet is used. Nonsolid LT4 formulations (i.e., liquid solution (LS) and soft gel (SG) capsule) were manufactured to overcome the limitations of LT4 tablet. This study was conceived to evaluate the performance of nonsolid LT4 formulations in a real-life scenario. METHODS: Two institutions participated in the study that was conducted in two phases (i.e., enrollment and re-evaluation). Adults with autoimmune or postsurgical hypothyroidism and on LT4 from a few months were selected. A nonparametric statistical analysis for paired or unpaired data was performed. RESULTS: 121 consecutive cases were included. At the enrollment phase, a 52% of patients took the therapy at least 30 min before breakfast with no difference between tablet and SG/LS users. TSH was 1.65 mIU/L (0.86-2.70) in patients on LT4 tablet and 1.70 mIU/L (1.10-2.17) in those on SG/LS (p=0.66). At the re-evaluation phase, among the patients using correct LT4 assumption, the TSH value was stable in the tablet group (p=0.66). At the re-evaluation phase, among the patients using correct LT4 assumption, the TSH value was stable in the tablet group (p=0.66). At the re-evaluation phase, among the patients using correct LT4 assumption, the TSH value was stable in the tablet group (p=0.66). At the re-evaluation phase, among the patients using correct LT4 assumption, the TSH value was stable in the tablet group (p=0.66). At the re-evaluation phase, among the patients using correct LT4 assumption, the TSH value was stable in the tablet group (. CONCLUSION: The performance of nonsolid LT4 formulations is not influenced by correct or incorrect use of therapy. On the contrary, LT4 tablet does not guarantee euthyroidism when it is ingested without waiting for at least 30 minutes before breakfast. These new data, obtained in a real-life scenario, suggest that LT4 SG/LS should be regarded as first-line therapy for treating adults with newly diagnosed hypothyroidism.