68 Ga-DOTATOC PET/CT Imaging of a Muscular Solitary Fibrous Tumor.

ABSTRACT: A 73-year-old woman was referred for 68 Ga-DOTATOC PET/CT staging of a grade 2 pancreatic neuroendocrine tumor, which showed the primary pancreatic tumor, liver metastases, one left pleural metastasis, and high uptake in a mass of the right triceps brachii muscle. Two years before, she underwent 18 F-FDG PET/CT and 111 In-pentetreotide scan, respectively, with low and high uptake of each radiotracer in the triceps mass. Histopathological analysis revealed a solitary fibrous tumor. Immunohistochemistry showed no staining for SSTR-2 and SSTR-5, suggesting tumor overexpression of another somatostatin receptor. This case highlighted a potential pitfall on 68 Ga-DOTATOC PET/CT.

Absolute Lymphocyte Count After COVID-19 Vaccination Is Associated with Vaccine-Induced Hypermetabolic Lymph Nodes on 18F-FDG PET/CT: A Focus in Breast Cancer Care.

We aimed to predict the presence of vaccine-induced hypermetabolic lymph nodes (v-HLNs) on 18F-FDG PET/CT after coronavirus disease 2019 (COVID-19) vaccination and determine their association with lymphocyte counts. Methods: In this retrospective single-center study, we included consecutive patients who underwent 18F-FDG PET/CT imaging after messenger RNA- or viral vector-based COVID-19 vaccination between early March and late April 2021. Demographics, clinical parameters, and absolute lymphocyte count (ALC) were collected, and their association with the presence of v-HLNs in the draining territory was studied by logistic regression. Results: In total, 260 patients were eligible, including 209 (80%) women and 145 (56%) with breast cancer. The median age was 50 y (range, 23-96 y). The messenger RNA vaccine had been given to 233 (90%). Ninety (35%) patients had v-HLNs, with a median SUVmax of 3.7 (range, 2.0-26.3), and 74 (44%) displayed lymphopenia, with a median ALC of 1.4 × 109/L (range, 0.3-18.3 × 109/L). An age of no more than 50 y (odds ratio [OR], 2.2; 95% CI, 1.0-4.5), the absence of lymphopenia (OR, 2.2; 95% CI, 1.1-4.3), and less than a 30-d interval from the last vaccine injection to the 18F-FDG PET/CT (OR, 2.6; 95% CI, 1.3-5.6) were independent factors for v-HLNs on multivariate analysis. In breast cancer patients, the absence of lymphopenia was the only independent factor significantly associated with v-HLNs (OR, 2.9; 95% CI, 1.2-7.4). Conclusion: Patients with a normal ALC after COVID-19 vaccination were more likely to have v-HLNs on 18F-FDG PET/CT, both of which might be associated with a stronger immune response to vaccination.

Immune Response Visualized In Vivo by [18F]-FDG PET/CT after COVID-19 Vaccine.

Worldwide deployment of COVID-19 vaccines is in progress. Recent immune activation following vaccination can sometimes be seen in fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]-FDG PET/CT). As previously evidenced, FDG-avid axillary lymph node(s) are common in patients receiving vaccines against SARS-CoV-2, influenza virus, or human papillomavirus, and reflect a regional immune response. In addition, these findings may also be accompanied by an increased spleen glucose metabolism after the COVID-19 vaccine, which captures a systemic immune response. Hence, we provide here a clinical example demonstrating that immune response could be associated with increased glucose metabolism in lymphoid organs such as lymph nodes and the spleen, which are critical modulators of T cell immunity. We believe that it is of paramount importance that nuclear physicians should be able to recognize clinical and imaging features of such immune responses upon vaccination for COVID-19 and beyond.

18F-FDG PET/CT in Relapsed Endometrial Cancer Treated with Preoperative PD-1 Inhibitor Dostarlimab.

Dostarlimab is an immune checkpoint inhibitor (ICI) targeting the Programmed-Death-1 (PD-1) co-receptor, recently approved by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA) as a novel therapy for recurrent or advanced endometrial cancer. We report the case of a 64-year-old woman, experiencing vaginal recurrence with microsatellite instability high/hypermutated of a FIGO stage IA grade 2 endometrial endometrioid adenocarcinoma. She received preoperative chemotherapy with four cycles of carboplatin plus paclitaxel, with stable disease on pelvic magnetic resonance imaging (MRI) and fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT). Dostarlimab (500 mg intravenously every 3 weeks) was then introduced. The subsequent evaluation after three perfusions demonstrated a complete metabolic response on 18F-FDG PET/CT according to immunotherapy-modified PET response criteria in solid tumors (imPERCIST) criteria, then confirmed by MRI according to immune response evaluation criteria in solid tumors (iRECIST). This clinical description suggests that 18F-FDG PET/CT might take place among available tools for guiding the preoperative management for recurrent endometrial cancer patients receiving dostarlimab immunotherapy that should be further explored through clinical trials.

Prognostic value of inflammatory response biomarkers using peripheral blood and [18F]-FDG PET/CT in advanced NSCLC patients treated with first-line chemo- or immunotherapy.

OBJECTIVES: We aimed to compare the prognostic value of inflammatory biomarkers extracted from pretreatment peripheral blood and [18F]-FDG PET for estimating outcomes in non-small cell lung cancer (NSCLC) patients treated with first-line immunotherapy (IT) or chemotherapy (CT). MATERIALS AND METHODS: In this retrospective multicenter study, we evaluated 111 patients with advanced NSCLC who underwent baseline [18F]-FDG PET/CT before IT or CT between 2016 and 2019. Several blood inflammatory indices were evaluated: derived neutrophil-to-lymphocyte ratio (dNLR), platelet-to-lymphocyte ratio (PLR), C-reactive protein (CRP) and systemic immune-inflammation index (SII). FDG-PET inflammatory parameters were extracted from lymphoid tissues (BLR and SLR: bone marrow or spleen-to-Liver SUVmax ratios). Association with survival and relationships between parameters were evaluated using Cox prediction models and Spearman's correlation respectively. RESULTS: Overall, 90 patients were included (IT:CT) (51:39pts). Median PFS was 8.6:6.6 months and median OS was not reached:21.2 months. In the IT cohort, high dNLR (>3), high SII (≥1,270) and high SLR (0.77) were independent statistically significant prognostic factors for one-year progression-free survival (1y-PFS) and two-year overall survival (2y-OS) on multivariable analysis. In the CT cohort, high BLR (≥0.80) and high dNLR (>3) were associated with shorter 1y-PFS (HR 2.2, 95% CI 1.0-4.9) and 2y-OS (HR 3.4, 95CI 1.1-10.3) respectively, on multivariable analysis. Finally, BLR significantly but moderately correlated with most blood-based inflammatory indices (CRP, PLR and SII) while SLR was only associated with CRP (p < 0.01 for all). CONCLUSION: In advanced NSCLC patients undergoing first-line IT or CT, pretreatment blood and inflammatory factors evaluating the spleen or bone marrow on [18F]-FDG PET/CT provided prognostic information for 1y-PFS and 2y-OS. These biomarkers should be further evaluated for potential clinical application.

Long-term progression of non-invasive follicular thyroid neoplasm with papillary-like nuclear features: A single-center retrospective study of the French Marne-Ardennes thyroid cancer registry.

CONTEXT: Non-invasive forms of encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) were reclassified as non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) in order to reduce overtreatment. A few studies showed neck lymphadenopathy at diagnosis, or even distant metastasis in patients with NIFTP. OBJECTIVE: Our aim was to report the frequency, clinical features and long-term progression of histologically confirmed NIFTP, using data from the French Marne-Ardennes thyroid cancer registry, and to compare findings against FVPTC. METHODS: This was a retrospective study on data for follicular variant of PTC (FVPTC) diagnosed between 1975 and 2015 obtained from the specialized Marne-Ardennes thyroid cancer registry. Pathology reports were used to select appropriate cases from a large series, and FVPTC specimens were reviewed by endocrine pathologists. Strict diagnostic criteria were used for reclassification as NIFTP. RESULTS: In total, 115 cases were reviewed histologically out of 383 cases of FVPTC. Sixty-five met all criteria for NIFTP and were consequently reclassified. Incidence of NIFTP was 16.9% of cases of FVPTC. Fifty patients were women (76.9%); median age was 47 years. Mean NIFTP size was 2.6 cm. There were no significant differences in age, gender or tumor size between NIFTP and FVPTC. Fifty patients underwent total thyroidectomy and 15 lobectomy. There were no lymph node metastases at diagnosis, and none of the patients (N=17) who underwent central and/or lateral neck dissection had positive findings on microscopic examination. 46 patients (70.8%) received radioiodine (RAI). Patients were followed up for 1.9-27.3 years (median 14.6 years) after initial treatment. All patients remained in complete remission during follow-up. CONCLUSION: Consistently with previous studies, our results showed the indolent course of NIFTP and that risk of recurrence after complete resection is very low (zero in our cohort), even when size is ≥4cm and in absence of adjuvant RAI treatment. Prospective studies are needed to confirm those results.

Added value of 18F-fluorocholine positron emission tomography-computed tomography in presurgical localization of hyperfunctioning parathyroid glands after dual tracer subtraction scintigraphy failure: A retrospective study of 47 patients.

Hyperparathyroidism is a common endocrine disorder. The precise localization of causal parathyroid gland is crucial to guide surgical treatment. Several studies report the added value of 18F-fluorocholine (FCH) positron emission tomography-computed tomography (PET/CT) as second line imaging but rely on suboptimal first-line imaging using 99mTc-sestaMIBI dual phase scintigraphy. The aim of this study is to evaluate the percentage of successful parathyroid localization with FCH PET/CT after failure of a more sensitive first-line detection protocol associating neck ultrasonography and 99mTc-Pertechnetate/99mTc-sestaMIBI dual tracer subtraction scintigraphy.We included retrospectively 47 patients who underwent a FCH PET/CT as second line imaging for biologically proven primary hyperparathyroidism from November 2016 to October 2018 in Godinot Institute (Reims, France). 99mTc-Pertechnetate/99mTc-sestaMIBI dual tracer subtraction scintigraphy and neck ultrasonography were used as first-line imaging and failed to localize the causal parathyroid lesion in all cases.FCH PET/CT demonstrated at least 1 parathyroid target lesion in 29 patients (62%). 21/29 patients underwent surgery. Target lesions corresponded histologically to hyperfunctioning parathyroid glands for all 21 patients and surgery was followed by hyperparathyroidism biological resolution. Calcium serum levels were associated to FCH PET/CT positivity (P = .002) and a trend toward significance was seen for Parathyroid hormone (PTH) levels (P = .09).FCH PET/CT is a promising tool in second-line parathyroid imaging. Large prospective studies and cost-effectiveness analyses are needed to precise its role.

Micropapillary carcinoma: Description and rise in incidence in the French Marne-Ardennes thyroid cancer registry.

CONTEXT: Yearly incidence of thyroid cancer has nearly tripled in the past four decades, due to improvements in and better use of diagnostic procedures, enabling detection of smaller tumors, and notably micropapillary carcinoma (MPC: ≤10 mm). OBJECTIVES: The aim of our study was to confirm increasing incidence, to describe the characteristics and circumstances of discovery, and to examine the reasons for this rise in incidence of MPCs, based on the French Marne-Ardennes registry for 1975-2014. DESIGN: This was a retrospective observational cohort study. RESULTS: Two thousand six hundred and seventy-one patients with thyroid cancer were included for the period 1975-2014, with 966 (36.2%) MPCs. The percentage increased from 18.9% for 1975-1984 to 45.1% for 2005-2014. Standardized incidence per 100,000 patient-years increased from 0.86 for 1975-1984 to 6.20 for 2005-2014. Incidence increase was higher in women (ranging from 1.15 to 8.91) than in men (from 0.20 to 2.54). Incidence increased more in ≥50 year-olds (from 0.41 to 4.21) than in <50 year-olds (from 0.45 to 1.99). Most MPCs (84.6%) were discovered incidentally on histology, and were mainly unifocal (79.4%). Incidental MPCs were smaller, affected older patients and were less multifocal than those suspected before surgery. MPCs were associated with excellent survival and low morbidity, with <1.9% progression. CONCLUSION: The present study confirmed the large rise in incidence of MPCs reported elsewhere. Most MPCs were discovered incidentally on histological examination in the context of surgery for benign pathology. Changes in access to health care and in physicians' and pathologists' practices are likely explanations for our findings.

False-Positive Results in 18F-Fluorocholine PET/CT for a Thymoma in Workup of a Hereditary Primary Hyperparathyroidism.

We present the case of a severe familial primary hyperparathyroidism related to a germline deletion in the HRPT2 (CDC73) gene. Morphological explorations revealed 2 potential hyperfunctioning parathyroid glands: a left cervical lesion on the neck ultrasound, and an ectopic mediastinal lesion on the parathyroid scintigraphy using Tc-methoxyisobutylisonitrile and on F-fluorocholine PET/CT. Surgery removal and histopathological examination determined that the mediastinal mass corresponded to a thymoma and the cervical lesion to a parathyroid adenoma. Those interesting images illustrate that a thymoma can produce false-positive results both on Tc-methoxyisobutylisonitrile scintigraphy and F-fluorocholine PET/CT.

Periurethral Mass Mimicking Neoplasm After Injection of Macroplastique for Postprostatectomy Stress Incontinence: A Pitfall on 18F-FDG PET/CT.

A 64-year-old man underwent initial F-FDG PET/CT staging for gastric cardia adenocarcinoma, which showed the primary gastric tumor, several bone metastases, and high uptake in a periurethral mass mimicking pelvic neoplasm developed after injection of polydimethylsiloxane (Macroplastique) urethral bulking agent 6 years ago for postprostatectomy stress urinary incontinence. This case showed a very rare complication of silicon particle injection therapy, and the intense uptake is likely due to granulomatous reaction around the implant.

Temporal Uptake Patterns of 18F-Fluorocholine Among Hyperfunctioning Parathyroid Glands.

Optimal scan time of F-fluorocholine (FCH) PET/CT for localization of hyperfunctioning parathyroid glands is poorly documented. We report a small series of 9 histologically proven hyperfunctioning parathyroid gland with heterogeneous temporal uptake profile. Thirty-minute dynamic acquisition starting just after F-fluorocholine administration and delayed acquisition were recorded. Three different uptake patterns are seen (early washout, stable uptake, late increase) indicating the importance of an early (5-10 minutes) acquisition. A late acquisition (60 minutes) could be useful when the early acquisition is negative. No correlations were noted between uptake profile and histological or genetic results.