Deep Learning Denoising Improves and Homogenizes Patient [18F]FDG PET Image Quality in Digital PET/CT.

Given the constant pressure to increase patient throughput while respecting radiation protection, global body PET image quality (IQ) is not satisfactory in all patients. We first studied the association between IQ and other variables, in particular body habitus, on a digital PET/CT. Second, to improve and homogenize IQ, we evaluated a deep learning PET denoising solution (Subtle PETTM) using convolutional neural networks. We analysed retrospectively in 113 patients visual IQ (by a 5-point Likert score in two readers) and semi-quantitative IQ (by the coefficient of variation in the liver, CVliv) as well as lesion detection and quantification in native and denoised PET. In native PET, visual and semi-quantitative IQ were lower in patients with larger body habitus (p < 0.0001 for both) and in men vs. women (p ≤ 0.03 for CVliv). After PET denoising, visual IQ scores increased and became more homogeneous between patients (4.8 ± 0.3 in denoised vs. 3.6 ± 0.6 in native PET; p < 0.0001). CVliv were lower in denoised PET than in native PET, 6.9 ± 0.9% vs. 12.2 ± 1.6%; p < 0.0001. The slope calculated by linear regression of CVliv according to weight was significantly lower in denoised than in native PET (p = 0.0002), demonstrating more uniform CVliv. Lesion concordance rate between both PET series was 369/371 (99.5%), with two lesions exclusively detected in native PET. SUVmax and SUVpeak of up to the five most intense native PET lesions per patient were lower in denoised PET (p < 0.001), with an average relative bias of -7.7% and -2.8%, respectively. DL-based PET denoising by Subtle PETTM allowed [18F]FDG PET global image quality to be improved and homogenized, while maintaining satisfactory lesion detection and quantification. DL-based denoising may render body habitus adaptive PET protocols unnecessary, and pave the way for the improvement and homogenization of PET modalities.

A Phase II Redifferentiation Trial with Dabrafenib-Trametinib and 131I in Metastatic Radioactive Iodine Refractory BRAF p.V600E-Mutated Differentiated Thyroid Cancer.

PURPOSE: To evaluate the efficacy and safety of dabrafenib-trametinib-131I for the treatment of radioactive iodine refractory metastatic differentiated thyroid cancer (DTC) with a BRAF p.V600E mutation. PATIENTS AND METHODS: A prospective phase II trial including patients with RECIST progression within 18 months and no lesion > 3 cm. Following a baseline recombinant human (rh)TSH-stimulated diagnostic whole-body scan (dc1-WBS), dabrafenib and trametinib were given for 42 days. A second rhTSH-stimulated dc WBS (dc2-WBS) was done at day 28 and 131I (5.5 GBq-150 mCi after rhTSH) was administered at day 35. Primary endpoint was the 6-month RECIST objective response rate. In case of partial response (PR) at 6 or 12 months, a second treatment course could be given. Among 24 enrolled patients, 21 were evaluable at 6 months. RESULTS: Abnormal 131I uptake was present on 5%, 65%, and 95% of the dc1-WBS, dc2-WBS, and post-therapy scans, respectively. At 6 months, PR was achieved in 38%, stable disease in 52%, and progressive disease (PD) in 10%. Ten patients received a second treatment course: one complete response and 6 PRs were observed at 6 months. The median progression-free survival (PFS) was not reached. The 12- and 24-month PFS were 82% and 68%, respectively. One death due to PD occurred at 24 months. Adverse events (AE) occurred in 96% of the patients, with 10 grade 3-4 AEs in 7 patients. CONCLUSIONS: Dabrafenib-trametinib is effective in BRAF p.V600E-mutated DTC patients for restoring 131I uptake with PR observed 6 months after 131I administration in 38% of the patients.

Detection, resection and cure: a systematic review and meta-analysis of 18F-choline PET in primary hyperparathyroidism.

INTRODUCTION: Primary hyperparathyroidism (pHPT) is a common endocrine disorder caused by an autonomous overproduction of parathyroid hormone (PTH) by a parathyroid gland. Over the last decade, 18F-choline (FCH) PET has emerged as a highly performant imaging technique for guiding parathyroidectomy. As cure is the goal of surgery, the main aims of this study were to summarize patient-based sensitivity, positive predictive value (PPV), and cure rate of FCH PET guided surgery in the surgical management of pHPT. EVIDENCE ACQUISITION: We conducted a systematic review and metaanalysis according to the PRISMA Guidelines. A literature search was performed in the PubMed, Web of Science and Cochrane databases, last updated November 2022. Original articles on choline PET in patients with pHPT mentioning patient-based sensitivity, PPV and cure rate were retained. Quality of included studies was assessed using the QUADAS-2 Tool. Patient-based sensitivity, PPV and cure rate were pooled by using a random-effects model. EVIDENCE SYNTHESIS: Twenty-three studies including 1716 patients were included for quantitative assessment. FCH PET showed a pooled patient-based sensitivity of 93.8% (95% CI: 89.8-96.3) and PPV of 97% (95% CI: 92.8-98.8) in patients with pHPT. Parathyroid surgery was performed in 1129 patients. The pooled cure rate of PET-guided surgery was 92.8% (95% CI: 87.4-96.0). Heterogeneity was shown to be moderate for all effect sizes. CONCLUSIONS: FCH PET showed a high patient-based sensitivity, PPV and cure rate of PET guided surgery in patients with pHPT.

Thyroid 18F-fluorocholine uptake in patients with chronic autoimmune thyroiditis.

Objective: 18F-Fluorocholine (18FCH) PET/CT has high sensitivity for parathyroid adenoma detection and can reliably exclude malignancy in thyroid nodules with indeterminate cytology. Data regarding 18FCH uptake in chronic autoimmune thyroiditis (CAT) are scarce. We aimed to assess thyroid 18FCH uptake in CAT with biological and histological correlation. Methods: This is an ancillary study from the Chocolate trial (NCT02784223) that prospectively enrolled 107 patients planned for thyroid surgery. 18FCH PET/CT acquisitions were performed 20 and 60 min after injection. 18FCH uptake in the thyroid gland was assessed by measuring maximum (SUVmax) and mean (SUVmean) standardized uptake values. Thyrotropin, free thyroxine (FT4), thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies were collected. The intensity of thyroiditis and the degree of fibrosis were assessed on pathology. Results: CAT was evidenced in 19/107 (18%) patients. Of these, 13 (68%) displayed an increased and diffuse 18FCH thyroid uptake. This uptake pattern was not observed in patients without CAT. SUVmax and SUVmean were higher in patients with CAT than in those without (P < 0.001). At both acquisition times, SUVmax showed a monotonic relationship with the intensity of thyroiditis (Spearman ρ = 0.44 and 0.51, respectively, P < 0.001) and with the degree of fibrosis (Spearman ρ = 0.55 and 0.62, respectively, P < 0.001). SUVmax showed a linear relationship with TPOAb titers at 20 min (Pearson r = 0.54, P < 0.05; Spearman ρ = 0.59, P = 0.03). Conclusions: More than two-thirds of the patients with CAT present high and diffuse thyroid 18FCH uptake. This uptake pattern is highly specific to CAT and is correlated with pathology and TPOAb titers.

Artificial intelligence-based PET denoising could allow a two-fold reduction in [18F]FDG PET acquisition time in digital PET/CT.

PURPOSE: We investigated whether artificial intelligence (AI)-based denoising halves PET acquisition time in digital PET/CT. METHODS: One hundred ninety-five patients referred for [18F]FDG PET/CT were prospectively included. Body PET acquisitions were performed in list mode. Original "PET90" (90 s/bed position) was compared to reconstructed ½-duration PET (45 s/bed position) with and without AI-denoising, "PET45AI and PET45". Denoising was performed by SubtlePET™ using deep convolutional neural networks. Visual global image quality (IQ) 3-point scores and lesion detectability were evaluated. Lesion maximal and peak standardized uptake values using lean body mass (SULmax and SULpeak), metabolic volumes (MV), and liver SULmean were measured, including both standard and EARL1 (European Association of Nuclear Medicine Research Ltd) compliant SUL. Lesion-to-liver SUL ratios (LLR) and liver coefficients of variation (CVliv) were calculated. RESULTS: PET45 showed mediocre IQ (scored poor in 8% and moderate in 68%) and lesion concordance rate with PET90 (88.7%). In PET45AI, IQ scores were similar to PET90 (P = 0.80), good in 92% and moderate in 8% for both. The lesion concordance rate between PET90 and PET45AI was 836/856 (97.7%), with 7 lesions (0.8%) only detected in PET90 and 13 (1.5%) exclusively in PET45AI. Lesion EARL1 SULpeak was not significantly different between both PET (P = 0.09). Lesion standard SULpeak, standard and EARL1 SULmax, LLR and CVliv were lower in PET45AI than in PET90 (P < 0.0001), while lesion MV and liver SULmean were higher (P < 0.0001). Good to excellent intraclass correlation coefficients (ICC) between PET90 and PET45AI were observed for lesion SUL and MV (ICC ≥ 0.97) and for liver SULmean (ICC ≥ 0.87). CONCLUSION: AI allows [18F]FDG PET duration in digital PET/CT to be halved, while restoring degraded ½-duration PET image quality. Future multicentric studies, including other PET radiopharmaceuticals, are warranted.

Unusual increase in carcinoembryonic antigen despite response to selpercatinib in two patients with medullary thyroid cancer.

Introduction: Serum calcitonin (CT) and carcinoembryonic antigen (CEA) are valuable tumour markers in patients with medullary thyroid carcinoma (MTC). Both markers most often evolve in parallel after treatment. Selpercatinib (LOXO-292) is a highly selective RET kinase inhibitor indicated in advanced RET-mutant MTC patients. Cases presentation: In this study, we report two observations of RET-mutant progressive metastatic and symptomatic MTC patients who were treated with selpercatinib. Patient 1, a 61-year-old man, presented dyspnoea and diarrhoea at selpercatinib initiation with large neck lymph nodes and lung metastases. Patient 2, a 76-year-old man, had acute discomfort with flush and diarrhoea, with small but diffuse bone and liver disease. Both patients had an objective tumour response with rapid clinical improvement and RECIST 1.1 response (-90%) in patient 1. A rapid dramatic decrease in CT level was observed in both patients (-99% in both patients), while CEA levels gradually and sustainably increased after selpercatinib initiation (+207% at cycle 15 in patient 1 and + 835% at cycle 14 in patient 2). In both patients, 18FDG PET/CT did not show any abnormal uptake that could explain the CEA increase. Colonoscopy and oesogastric fibroscopy showed colonic polyposis with mild oesophagitis and gastritis in patient 1 and were normal in patient 2. Conclusion: These observations show an unusual and lasting increase in serum CEA in two MTC patients who exhibited an objective tumour response to selpercatinib. The mechanism behind this unexpected rise in CEA level remains unknown. The frequency of this evolving profile will be determined in further phase III studies.

Subdiaphragmatic Lymph Nodes Uptake on 18F-FDG PET/CT After COVID-19 Vaccination in the Thigh.

ABSTRACT: Since worldwide COVID-19 vaccination, 18F-FDG uptake in reactive axillary lymph nodes has been frequently observed in PET/CT studies. We describe a patient with breast cancer who underwent 18F-FDG PET/CT 7 days after receiving COVID-19 vaccination in the right thigh. 18F-FDG uptake was observed in nonenlarged right-sided inguinal, iliac, and para-aortic lymph nodes. As the thigh can be used as an alternate site for COVID-19 vaccine injection in case of lymphedema in both arms or for adequate axillary staging in patients with breast cancer, physicians should be aware of such 18F-FDG uptake pattern.

PSMA Expression in Differentiated Thyroid Cancer: Association With Radioiodine, 18FDG Uptake, and Patient Outcome.

CONTEXT: Little is known about prostate-specific membrane antigen (PSMA) expression in patients with cervical involvement of differentiated thyroid cancer (DTC). OBJECTIVE: We investigated PSMA expression in neck persistent/recurrent disease (PRD) using immunohistochemistry and the association with radioiodine (RAI) or 18-fluorodeoxyglucose (18FDG) uptake, and patient outcome. DESIGN, SETTING, AND PATIENTS: Data from 44 consecutive DTC patients who underwent neck reoperation from 2006 to 2018 in a comprehensive cancer center. MAIN OUTCOME MEASURE(S): Immunostaining was performed with vascular endothelial marker CD31 and PSMA. PSMA expression was quantified using the immunoreactive score (IRS). RAI and 18FDG uptake were assessed before surgery using posttherapeutic RAI scintigraphy and 18FDG positron emission tomography with computed tomography. Mean follow-up after reintervention was 6.5 ±â€…3.7 years. RESULTS: Thirty patients (68%) showed at least 1 PSMA-positive lesion (IRS ≥ 2) with similar proportions in RAI-positive and RAI-negative patients (75% vs 66%). In RAI-negative patients, however, the proportion of PSMA-positive disease (79% vs 25%, P < 0.01) and the mean IRS (4.0 vs 1.0, P = 0.01) were higher in 18FDG-positive than in 18FDG-negative patients. Furthermore, mean IRS was higher in patients ≥ 55 years, large primary tumors (>40 mm) or aggressive subtypes, and was correlated with structural disease at last follow-up. Strong PSMA expression (IRS ≥ 9) was associated with shorter progression-free survival (PFS). CONCLUSIONS: Our findings show that PSMA expression was present in two-thirds of patients with neck PRD, that it was related to poor prognostic factors and that very high expression was associated with poorer PFS. This preliminary study may offer new perspectives for the management of RAI-refractory DTC.

Upfront F18-choline PET/CT versus Tc99m-sestaMIBI SPECT/CT guided surgery in primary hyperparathyroidism: the randomized phase III diagnostic trial APACH2.

BACKGROUND: The common endocrine disorder primary hyperparathyroidism (PHPT) can be cured by surgery. Preoperative localization of parathyroid adenoma (PTA) by imaging is a prerequisite for outpatient minimally invasive parathyroidectomy (MIP). Compared to inpatient bilateral cervical exploration (BCE) which is performed if imaging is inconclusive, MIP is superior in terms of cure and complication rates and less costly. The imaging procedure F18-choline (FCH) PET/CT outperforms Tc99m-sestaMIBI (MIBI) SPECT/CT for PTA localization, but it is much costlier. The aim of this study is to identify the most efficient first-line imaging modality for optimal patient care in PHPT without added cost to society. METHODS: We will conduct a multicenter open diagnostic intervention randomized phase III trial comparing two diagnostic strategies in patients with PHPT: upfront FCH PET/CT versus MIBI SPECT/CT. The primary endpoint is the proportion of patients in whom the first-line imaging method results in successful MIP and cure. Follow-up including biological tests will be performed 1 and 6 months after surgery. The main secondary endpoint is the social cost of both strategies. Other secondary endpoints are as follows: FCH PET/CT and MIBI SPECT/CT diagnostic performance, performance of surgical procedure and complication rate, FCH PET/CT inter- and intra-observer variability and optimization of FCH PET/CT procedure. Fifty-eight patients will be enrolled and randomized 1:1. DISCUSSION: FCH PET/CT is a highly efficient but expensive imaging test for preoperative PTA localization and costs three to four times more than MIBI SPECT/CT. Whether FCH PET/CT improves patient outcomes compared to the reference standard MIBI SPECT/CT is unknown. To justify its added cost, FCH PET/CT-guided parathyroid surgery should lead to improved patient management, resulting in higher cure rates and fewer BCEs and surgical complications. In the previous phase II APACH1 study, we showed that second-line FCH PET/CT led to a cure in 88% of patients with negative or inconclusive MIBI SPECT/CT. BCE could be avoided in 75% of patients and surgical complication rates were low. We therefore hypothesize that upfront FCH PET/CT would improve patient care in PHPT and that the reduction in clinical costs would offset the increase in imaging costs. TRIAL REGISTRATION: NCT04040946 , registered August 1, 2019.  Protocol version Version 2.1 dated from 2020/04/23.

Diagnostic and prognostic value of a 7-panel mutation testing in thyroid nodules with indeterminate cytology: the SWEETMAC study.

PURPOSE: The aim of this prospective study (ClinicalTrials.gov: NCT01880203) was to evaluate the diagnostic and prognostic value of a 7-panel mutation testing in the aspirates of thyroid nodules with indeterminate cytology (IC). METHODS: Eligible patients had a thyroid nodule ≥15 mm with IC (Bethesda III-V) for which surgery had been recommended. Detection of BRAF and RAS mutations was performed using pyrosequencing and RET/PTC and PAX8/PPARγ rearrangements using Real-Time quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Among 131 nodules with IC, 21 (16%) were malignant including 20 differentiated cancers and one thyroid lymphoma. Molecular abnormalities were identified in 15 nodules with IC corresponding to 10 malignant and 5 benign tumours. BRAF mutation was detected in 4 nodules all corresponding to classic PTC, and PAX8/PPARγ rearrangement in 2 HCC. In contrast, RAS mutation was identified in eight nodules, of which four were malignant, and one RET/PTC3 rearrangement in a follicular adenoma. This data resulted in an accuracy of 88%, sensitivity of 48%, specificity of 95%, positive-predictive value of 67%, and negative-predictive value of 91%. After a 56 month's follow-up, the proportion of excellent response was similar in patients with molecular alterations (67%) and those without (60%). CONCLUSIONS: By increasing the overall risk of cancer from 16 to 67% in mutated nodules and by diminishing it to 9% in wild-type, this study confirms the relevance of the 7-panel mutation testing in the diagnostic of nodules with IC. Genetic testing, however, did not predict outcome in the cancer patient subgroup.

18F-Fluorocholine Positron Emission Tomography/Computed Tomography is a Highly Sensitive but Poorly Specific Tool for Identifying Malignancy in Thyroid Nodules with Indeterminate Cytology: The Chocolate Study.

Background: Refining the risk of malignancy in patients presenting with thyroid nodules with indeterminate cytology (IC) is a critical challenge. We investigated the performances of 18F-fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) to predict malignancy. Methods: Between May 2016 and March 2019, 107 patients presenting with a thyroid nodule ≥15 mm with IC and eligible for surgery were included in this prospective study. Head-and-neck PET/CT acquisitions were performed 20 and 60 minutes after injection of 1.5 MBq/kg of FCH. PET/CT acquisition was scored positive when maximal standardized uptake value in the IC nodule was higher than in the thyroid background. Pathology was the gold standard for diagnosis. Results: At pathology, 19 (18%) nodules were malignant, 87 were benign, and one was a noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Sensitivity, specificity, accuracy, positive-predictive value (PPV), and negative-predictive value (NPV) of FCH PET/CT in detecting cancer or NIFTP were 90%, 50%, 55%, 29%, and 96% at 20 minutes and 85%, 49%, 67%, 28%, and 94% at 60 minutes, respectively. Higher specificity (58% vs. 33%, p = 0.01) was observed in nononcocytic (n = 72) than in oncocytic IC nodules (n = 35). The pre-PET/CT probability of cancer or NIFTP in Bethesda III-IV nodules was 11% and the post-PET/CT probability was 19% in PET-positives and 0% in PET-negatives. In retrospective analysis, 42% of surgeries would have been unnecessary after PET/CT and 81% before (p < 0.001), resulting in a hypothetical 48% reduction (95% confidence interval [32-64]). Conclusions: FCH PET/CT offers high NPV to reliably exclude cancer in PET-negative IC nodules, but suffers from low PPV, particularly in those with oncocytic cytology. ClinicalTrials.gov identifier: NCT02784223.

Tumor burden of persistent disease in patients with differentiated thyroid cancer: correlation with postoperative risk-stratification and impact on outcome.

BACKGROUND: In patients with differentiated thyroid cancer (DTC), tumor burden of persistent disease (PD) is a variable that could affect therapy efficiency. Our aim was to assess its correlation with the 2015 American Thyroid Association (ATA) risk-stratification system, and its impact on response to initial therapy and outcome. METHODS: This retrospective cohort study included 618 consecutive DTC patients referred for postoperative radioiodine (RAI) treatment. Patients were risk-stratified using the 2015 ATA guidelines according to postoperative data, before RAI treatment. Tumor burden of PD was classified into three categories, i.e. very small-, small- and large-volume PD. Very small-volume PD was defined by the presence of abnormal foci on post-RAI scintigraphy with SPECT/CT or 18FDG PET/CT without identifiable lesions on anatomic imaging. Small- and large-volume PD were defined by lesions with a largest size < 10 or ≥ 10 mm respectively. RESULTS: PD was evidenced in 107 patients (17%). Mean follow-up for patients with PD was 7 ± 3 years. The percentage of large-volume PD increased with the ATA risk (18, 56 and 89% in low-, intermediate- and high-risk patients, respectively, p < 0.0001). There was a significant trend for a decrease in excellent response rate from the very small-, small- to large-volume PD groups at 9-12 months after initial therapy (71, 20 and 7%, respectively; p = 0.01) and at last follow-up visit (75, 28 and 16%, respectively; p = 0.04). On multivariate analysis, age ≥ 45 years, distant and/or thyroid bed disease, small-volume or large-volume tumor burden and 18FDG-positive PD were independent risk factors for indeterminate or incomplete response at last follow-up visit. CONCLUSIONS: The tumor burden of PD correlates with the ATA risk-stratification, affects the response to initial therapy and is an independent predictor of residual disease after a mean 7-yr follow-up. This variable might be taken into account in addition to the postoperative ATA risk-stratification to refine outcome prognostication after initial treatment.

HYPHYCA: a prospective study in 613 patients conducting a comprehensive analysis for predictive factors of physiological 18F-FDG anal uptake.

BACKGROUND: Anal cancer is a relatively rare tumor of which incidence increases in developed countries. 18F-FDG PET has been increasingly used for its post radio-chemotherapy evaluation. However, several authors have reported the risk of local false-positive findings leading to low specificity and positive predictive values. These false-positive results could be due to post-radiotherapy inflammation or infection but certainly also to physiological anal canal uptake that is observed on a regular basis in clinical practice. The purpose of this prospective study (NCT03506529; HYPHYCA) was therefore to seek predictive factors of physiological anal canal hypermetabolism. MATERIALS AND METHODS: Over a 2-month period, patients aged 18 years old and more, referred for 18F-FDG PET-CT at two EARL-accredited PET centers were included, after obtaining their informed and written consent. They were asked to fill in a questionnaire including seven closed questions about usual intestinal transit, ongoing medications relative to intestinal transit, history of digestive, and anal and/or pelvic diseases. Age, gender, and body mass index (BMI) were recorded. A single nuclear medicine physician visually and quantitatively analyzed anal canal uptake (SUVmax_EARL) and assessed visual rectal content (air, feces, or both) and the largest rectal diameter (mm). RESULTS: Six hundred and thirteen patients were included (sex ratio F/M = 0.99) and 545 (89%) questionnaires were entirely completed. Significantly more males presented anal canal hypermetabolism (sex ratio (M/F) = 1.18 versus 0.85, p = 0.048). Moreover, patients with anal canal hypermetabolism had higher BMI (27.6 (5.7) kg/m2 versus 23.9 (4.5) kg/m2, p < 0.0001), higher rate of hemorrhoid history (43% versus 27%, p = 0.016), and higher rate of rectum filled with only feces (21% versus 12%, p = 0.019) as compared to patients with no anal canal uptake. On logistic regression, all these variables were found to be independent predictors of the occurrence of an anal canal hypermetabolism. Odds ratio were 1.16 (1.12-1.20) per unit of BMI (kg/m2) (p < 0.0001), 1.48 (1.04-2.11) for males (p = 0.030), 1.64 (1.10-2.45) for hemorrhoids history (p = 0.016), and 1.94 (1.147-3.22) for the rectum filled with only feces (p = 0.010). CONCLUSION: According to our study, the predictive factors of physiological anal canal hypermetabolism are high BMI, male gender, hemorrhoid history, and rectum filled with only feces. This may pave the way to a more specific interpretation of post radio-chemotherapy PET evaluations of anal canal cancer, provided that other studies are conducted in this specific population. TRIAL REGISTRATION: This prospective study was registered at Clinicaltrial.gov: NCT03506529; HYPHYCA on April 24, 2018.

Thyroid Incidentaloma on 18F-fluorocholine PET/CT and 68Ga-PSMA PET/CT Revealing a Medullary Thyroid Carcinoma.

A 66-year-old man with prostate cancer underwent F-fluorocholine PET/CT and thereafter Ga-labeled prostate-specific membrane antigen PET/CT to explore a rising prostate-specific antigen level. Both PET/CT studies showed a thyroid incidentaloma of the right lobe. Neck ultrasound confirmed the presence of a 16-mm right thyroid nodule. The serum calcitonin level was moderately increased at 25 ng/mL (<10). Cytology was non-diagnostic (Bethesda I). A right lobectomy was performed and pathology revealed a 15-mm medullary thyroid cancer. Two months after surgery, the calcitonin level returned to normal at 3.3 ng/mL.

Recombinant Thyrotropin vs Levothyroxine Withdrawal in 131I Therapy of N1 Thyroid Cancer: A Large Matched Cohort Study (ThyrNod).

CONTEXT: Recombinant human thyrotropin (rhTSH) has been shown to be an effective stimulation method for radioactive iodine (RAI) therapy in differentiated thyroid cancer, including in those with nodal metastases (N1 DTC). OBJECTIVES: To demonstrate the noninferiority of rhTSH vs thyroid hormone withdrawal (THW) in preparation to RAI regarding disease status at the first evaluation in the real-life setting in patients with N1 DTC. DESIGN: This was a French multicenter retrospective study. Groups were matched according to age (<45/≥45 years), number of N1 nodes (≤5/>5 lymph nodes), and stage (pT1-T2/pT3). RESULTS: The cohort consisted of 404 patients pT1-T3/N1/M0 DTC treated with rhTSH (n = 205) or THW (n = 199). Pathological characteristics and initially administrated RAI activities (3.27 ± 1.00 GBq) were similar between the two groups. At first evaluation (6 to 18 months post-RAI), disease-free status was defined by thyroglobulin levels below threshold and a normal ultrasound. Disease-free rate was not inferior in the rhTSH group (75.1%) compared with the THW group (71.9%). The observed difference between the success rates was 3.3% (-6.6 to 13.0); rhTSH was therefore considered noninferior to THW because the upper limit of this interval was <15%. At the last evaluation (29.7 ± 20.7 months for rhTSH; 36.7 ± 23.8 months for THW), 83.5% (rhTSH) and 81.5% (THW) of patients achieved a complete response. This result was not influenced by any of the known prognostic factors. CONCLUSIONS: A preparation for initial RAI treatment with rhTSH was noninferior to that with THW in our series of pT1-T3/N1/M0-DTC on disease-free status outcomes at the first evaluation and after 3 years.

Optimization of a dedicated protocol using a small-voxel PSF reconstruction for head-and-neck 18FDG PET/CT imaging in differentiated thyroid cancer.

BACKGROUND: 18FDG PET/CT is crucial before neck surgery for nodal recurrence localization in iodine-refractory differentiated or poorly differentiated thyroid cancer (DTC/PDTC). A dedicated head-and-neck (HN) acquisition performed with a thin matrix and point-spread-function (PSF) modelling in addition to the whole-body PET study has been shown to improve the detection of small cancer deposits. Different protocols have been reported with various acquisition times of HN PET/CT. We aimed to compare two reconstruction algorithms for disease detection and to determine the optimal acquisition time per bed position using the Siemens Biograph6 with extended field-of-view. METHODS: Twenty-one consecutive and unselected patients with DTC/PDTC underwent HN PET/CT acquisition using list-mode. PET data were reconstructed, mimicking five different acquisition times per bed position from 2 to 10 min. Each PET data set was reconstructed using 3D-ordered subset expectation maximisation (3D-OSEM) or iterative reconstruction with PSF modelling with no post filtering (PSFallpass). These reconstructions resulted in 210 anonymized datasets that were randomly reviewed to assess 18FDG uptake in cervical lymph nodes or in the thyroid bed using a 5-point scale. Noise level, maximal standard uptake values (SUVmax), tumour/background ratios (TBRs) and dimensions of the corresponding lesion on the CT scan were recorded. In surgical patients, the largest tumoral size of each lymph node metastasis was measured by a pathologist. RESULTS: The 120 HN PET studies of the 12 patients with at least 1 18FDG focus scored malignant formed the study group. Noise level significantly decreased between 2 and 4 min for both 3D-OSEM and PSFallpass reconstructions (p < 0.01). TBRs were similar for all the acquisition times for both 3D-OSEM and PSFallpass reconstructions (p = 0.25 and 0.44, respectively). The detection rate of malignant foci significantly improved from 2 to 10 min for PSFallpass reconstruction (20/26 to 26/26; p = 0.01) but not for 3D-OSEM (15/26 to 19/26; p = 0.26). For each of the five acquisition times, PSFallpass detected more malignant foci than 3D-OSEM (p < 0.01). In the seven surgical patients, PSFallpass evidenced smaller malignant lymph nodes than 3D-OSEM at 8 and 10 min. At 10 min, the mean size of the lymph node metastases neither detected with PSFallpass nor 3D-OSEM was 3 ± 0.6 mm vs 5.8 ± 1.1 mm for those detected with PSFallpass only and 10.9 ± 3.3 for those detected with both reconstructions (p < 0.001). CONCLUSIONS: PSFallpass HN PET improves lesion detectability as compared with 3D-OSEM HN PET. PSFallpass with an acquisition time between 8 and 10 min provides the best performance for tumour detection.

F18-choline PET/CT guided surgery in primary hyperparathyroidism when ultrasound and MIBI SPECT/CT are negative or inconclusive: the APACH1 study.

PURPOSE: To evaluate the sensitivity of F18-choline (FCH) PET/CT for parathyroid adenoma detection prior to surgery in patients with primary hyperparathyroidism and negative or inconclusive cervical ultrasound and Tc99m-sestaMIBI SPECT/CT. METHODS: We conducted a prospective bicentric study (NCT02432599). All patients underwent FCH PET/CT. The result was scored positive, inconclusive or negative. The number of uptakes and their sites were recorded. The FCH PET/CT result guided the surgical procedure (minimally invasive parathyroidectomy, bilateral cervical exploration, or other in case of multiple or ectopic foci). FCH PET/CT results were compared to the surgical and pathological findings and the follow-up. RESULTS: Twenty-five patients were included. Mean calcium and PTH levels prior to surgery were 2.76 ± 0.17 mmol/l and 94.8 ± 37.4 ng/l. Nineteen (76%) FCH PET/CTs were scored positive, 3 (12%) inconclusive and 3 (12%) negative, showing 21 cases of uniglandular disease, including 1 ectopic localization and 1 case of multiglandular (3 foci) disease. Mean lesion size was 13.1 ± 8.6 mm. Twenty-four patients underwent surgery. FCH PET/CT guided surgery in 22 (88%) patients, allowing for 17 minimally invasive parathyroidectomies, 1 bilateral cervical exploration for multifocality and 4 other surgical procedures. Two patients with negative FCH-PET/CT underwent bilateral cervical exploration. When dichotomizing the FCH PET/CT results, thereby classifying the inconclusive FCH PET/CT results as positive, the per lesion and per patient sensitivities were 91.3% (95%CI: 72.0-98.9) and 90.5% (95%CI: 69.6-98.8) and the corresponding positive predictive values were 87.5% (95%CI: 67.6-97.3) and 86.4% (95%CI: 65.1-97.1), respectively. Twenty-one (88%) patients were considered cured after surgery. Their mean calcium level after surgery was 2.36 ± 0.17 mmol/l. CONCLUSIONS: Preoperative FCH PET/CT has a high sensitivity and positive predictive value for parathyroid adenoma detection in patients with primary hyperparathyroidism and negative or inconclusive conventional imaging results. Bilateral cervical exploration could be avoided in the majority (75%) of patients.

Shear Wave Elastography in Thyroid Nodules with Indeterminate Cytology: Results of a Prospective Bicentric Study.

BACKGROUND: The clinical management of thyroid nodules with indeterminate cytology (IC) remains challenging. The role of shear wave elastography (SWE) in this setting is controversial. The aim of the study was to assess the performances of SWE in terms of prediction of malignancy, reproducibility, and combined analysis with ultrasound (US) examination in thyroid nodules with IC. METHODS: This prospective study was conducted in two referral centers. Eligible patients had a thyroid nodule ≥15 mm with IC (Bethesda class III-V) for which surgery had been recommended. Patients underwent a standardized US evaluation combined with a SWE exam followed by surgery. SWE parameters included mean (meanEI; kPa) and max (maxEI) elasticity values, and ratio (meanEI nodule/parenchyma). RESULTS: One hundred and thirty-one nodules (median size 30 mm) in 131 patients were studied. IC was class III in 28%, class IV in 64%, and class V in 8% of cases. After surgery, 21 (16%) nodules were malignant, including nine papillary thyroid cancers (PTC), six follicular thyroid cancers, five poorly differentiated carcinomas, and one large B-cell lymphoma. SWE parameters were similar in benign and malignant nodules, including meanEI (20.2 vs. 19.6 kPa), maxEI (34.3 vs. 32.5 kPa), and ratio (1.57 vs. 1.38). In malignant nodules, meanEI, maxEI, and ratio were higher in the classic PTC variants (n = 4) than in the other PTC variants (n = 5; p < 0.02) and in non-PTC tumors (n = 12; p < 0.005). Intra- and inter-observer coefficients of variations for meanEI in nodules were 23% and 26%, respectively. The French Thyroid Imaging Reporting and Data System score, the American Thyroid Association US classification, and the EU-Thyroid Imaging Reporting and Data System were not associated with malignancy. CONCLUSIONS: Despite high elasticity values in classic PTC variants, conventional SWE indexes failed to discriminate between benign and malignant tumors in thyroid nodules with IC.

Propranolol 18F-FDG PET/CT: A Noninvasive Approach for Differential Diagnosis of Hibernoma and Liposarcoma.

A 76-year-old woman was referred for F-FDG PET/CT assessment of a colorectal cancer. A 9-cm F-FDG-avid fatty mass was depicted in the right thigh, suggesting either hibernoma or liposarcoma. Because MRI could not rule out well-differentiated liposarcoma, and biopsy was difficult, surveillance was decided. Follow-up PET/CT showed an increase of F-FDG uptake in the fatty mass. We repeated PET/CT after oral administration of 60 mg of propranolol 1 hour before F-FDG injection. A dramatic decrease in F-FDG uptake was observed, strongly supporting the diagnosis of hibernoma.