Role of 18F-FDG PET/CT in Head and Neck Squamous Cell Carcinoma: Current Evidence and Innovative Applications.

This article provides an overview of the use of 18F-FDG PET/CT in various clinical scenarios of head-neck squamous cell carcinoma, ranging from initial staging to treatment-response assessment, and post-therapy follow-up, with a focus on the current evidence, debated issues, and innovative applications. Methodological aspects and the most frequent pitfalls in head-neck imaging interpretation are described. In the initial work-up, 18F-FDG PET/CT is recommended in patients with metastatic cervical lymphadenectomy and occult primary tumor; moreover, it is a well-established imaging tool for detecting cervical nodal involvement, distant metastases, and synchronous primary tumors. Various 18F-FDG pre-treatment parameters show prognostic value in terms of disease progression and overall survival. In this scenario, an emerging role is played by radiomics and machine learning. For radiation-treatment planning, 18F-FDG PET/CT provides an accurate delineation of target volumes and treatment adaptation. Due to its high negative predictive value, 18F-FDG PET/CT, performed at least 12 weeks after the completion of chemoradiotherapy, can prevent unnecessary neck dissections. In addition to radiomics and machine learning, emerging applications include PET/MRI, which combines the high soft-tissue contrast of MRI with the metabolic information of PET, and the use of PET radiopharmaceuticals other than 18F-FDG, which can answer specific clinical needs.

18F-Fluoroethylcholine PET/CT Radiomic Analysis for Newly Diagnosed Prostate Cancer Patients: A Monocentric Study.

AIM: The aim of this study is to assess whether there are some correlations between radiomics and baseline clinical-biological data of prostate cancer (PC) patients using Fluorine-18 Fluoroethylcholine (18F-FECh) PET/CT. METHODS: Digital rectal examination results (DRE), Prostate-Specific Antigen (PSA) serum levels, and bioptical-Gleason Score (GS) were retrospectively collected in newly diagnosed PC patients and considered as outcomes of PC. Thereafter, Volumes of interest (VOI) encompassing the prostate of each patient were drawn to extract conventional and radiomic PET features. Radiomic bivariate models were set up using the most statistically relevant features and then trained/tested with a cross-fold validation test. The best bivariate models were expressed by mean and standard deviation to the normal area under the receiver operating characteristic curves (mAUC, sdAUC). RESULTS: Semiquantitative and radiomic analyses were performed on 67 consecutive patients. tSUVmean and tSkewness were significant DRE predictors at univariate analysis (OR 1.52 [1.01; 2.29], p = 0.047; OR 0.21 [0.07; 0.65], p = 0.007, respectively); moreover, tKurtosis was an independent DRE predictor at multivariate analysis (OR 0.64 [0.42; 0.96], p = 0.03) Among the most relevant bivariate models, szm_2.5D.z.entr + cm.clust.tend was a predictor of PSA levels (mAUC 0.83 ± 0.19); stat.kurt + stat.entropy predicted DRE (mAUC 0.79 ± 0.10); cm.info.corr.1 + szm_2.5D.szhge predicted GS (mAUC 0.78 ± 0.16). CONCLUSIONS: tSUVmean, tSkewness, and tKurtosis were predictors of DRE results only, while none of the PET parameters predicted PSA or GS significantly; 18F-FECh PET/CT radiomic models should be tested in larger cohort studies of newly diagnosed PC patients.

Whole-Body Radioiodine Effective Half-Life in Patients with Differentiated Thyroid Cancer.

Background: Radioactive 131I (RAI) therapy is used in patients with differentiated thyroid cancer (DTC) after total thyroidectomy for remnant ablation, adjuvant treatment or treatment of persistent disease. 131I retention data, which are used to indicate the time at which a 131I treated DTC patient can be released from the hospital, may bring some insights regarding clinical factors that prolong the length of hospitalization. The aim of this study was to investigate the 131I whole-body retention in DTC patients during 131I therapy. Methods: We monitored 166 DTC patients to follow the 131I whole-body retention during 131I therapy with a radioactivity detector fixed on the ceiling of each protected room. A linear regression fit permitted us to estimate the whole-body 131I effective half-life in each patient, and a relationship was sought between patients' clinical characteristics and whole-body effective 131I half-life. Results: The effective 131I half-life ranged from 4.08 to 56.4 h. At multivariable analysis, longer effective 131I half-life was related to older age and extensive extra-thyroid disease. Conclusions: 131I effective half-life during 131I treatment in DTC patients is highly variable among patients and is significantly longer in older and in patients with RAI uptake in large thyroid remnants or in extrathyroidal disease that significantly prolongs the whole-body retention of 131I.

FDG-CT/PET false positive case in hip prosthesis: a clue to avoid error.

A 62 years old woman 6 months after left total hip prosthesis referred to our institution for persistent pain and warm, stiff, and swollen joint. 18F-FDG CT/PET Images showed an intense focal uptake corresponding to the external margin of inter-trochanteric region of prosthesis and inside the stem inferiorly, but common decision was to reconstruct PET images without attenuation correction and now showed a complete and unexpected disappearance of focal and pathological FDG uptake. This case shows the potential propagation of CT artifacts into PET emission data close to metal implants and should be taken in account together to SUV values.

Management of differentiated thyroid cancer through nuclear medicine facilities during Covid-19 emergency: the telemedicine challenge.

PURPOSE: To investigate whether a telemedicine service (TMS) carried out during the Covid-19 pandemic impacted on management of patients with differentiated thyroid cancer (DTC). METHODS: We retrospectively reviewed the number and the findings of outpatient visits in DTC subjects referred between March 11, 2020, and May 31, 2020, during the Covid-19 pandemic at the Radiometabolic Unit of the University of Naples Federico II. Office visits scheduled in March and May 2020 were converted in teleconsultation reaching all patients planned for an in-ward access to advise them to use the TMS for all clinical necessity. The number and the findings of DTC patients evaluated by in-ward access in the corresponding period of 2019 were also assessed for direct comparison. RESULTS: The number of outpatient visits performed by TMS during the pandemic (n = 445) and by in-ward access in the corresponding period of 2019 (n = 525) was comparable with only 15% of outpatient evaluations missed. CONCLUSIONS: Our findings demonstrate the utility of telemedicine tools to avoid the potential negative impact of interruption or postponement of diagnostic and/or therapeutic procedures. Therefore, investments in medical network system development, including the implementation of telehealth approaches, should be encouraged at national and international levels.

Identification and typing of cardiac amyloidosis by noninvasive imaging: Two cases for two patterns.

Cardiac amyloidosis is a restrictive infiltrative cardiomyopathy burdened by high mortality. The two more common forms are immunoglobulin light-chain amyloidosis and transthyretin-related amyloidosis with different prognoses and treatments. However, distinguishing between them is challenging. Appropriate utilization of the different available imaging techniques in the evaluation of patients with known or suspected cardiac amyloidosis is mandatory. We report two cases with cardiac amyloidosis of different etiology and with distinct imaging patterns. In the first case, the negative 99mTc-diphosphonate imaging was useful to support the diagnosis of cardiac amyloid light-chain; the second case emphasized the utility of whole-body scintigraphy in recognizing transthyretin-related cardiac amyloidosis and the potential role of cadmium-zinc-telluride SPECT imaging for the evaluation of segmental distribution of cardiac disease. Both cases support the growing interest in looking for noninvasive methods to type cardiac amyloidosis in the place of invasive myocardial biopsy highlighting both possibilities and limitations of available imaging techniques in diagnosis and treatment monitoring.