Ronan Abgral

UNLABELLED: Posttreatment surveillance for the recurrence of head and neck squamous cell carcinoma (HNSCC) is a diagnostic challenge. Tissue distortion from radiation and surgery can obscure early detection of recurrence by conventional follow-up approaches such as physical examination, CT, and MRI. Several studies have shown that 18F-FDG PET may be an effective technique for the detection of persistent, recurrent, and distant metastatic HNSCC after treatment. The aim of this prospective study was to determine the benefits of hybrid 18F-FDG PET/CT in detecting a subclinical locoregional recurrence of HNSCC and distant metastases. The study patients were considered cured of HNSCC on the basis of 12 mo of negative findings on conventional follow-up. We also assessed the diagnostic accuracy of 18F-FDG PET/CT in these patients. METHODS: Ninety-one patients cured of HNSCC without any clinical evidence of recurrence were included. Whole-body 18F-FDG PET/CT examination was performed 11.6+/-4.4 mo after the end of the treatment. The gold standard was histopathology or 6 mo of imaging follow-up. RESULTS: The whole-body 18F-FDG PET/CT examinations had negative results in 52 patients and positive results in 39. Nine of these patients who exhibited abnormal 18F-FDG uptake in the head and neck area did not have recurrent HNSCC (false-positive). Thirty had proven recurrence. The sensitivity and specificity of 18F-FDG PET/CT in this study for the diagnosis of HNSCC recurrence were 100% (30/30) and 85% (52/61), respectively. The positive predictive value was 77% (30/39). The negative predictive value was 100% (52/52). The overall accuracy was 90% (82/91). CONCLUSION: The results of our study confirm the high effectiveness of 18F-FDG PET/CT in the assessment of HNSCC recurrence and suggest that 18F-FDG PET/CT is more accurate than conventional follow-up physical examination alone in the assessment of recurrence after previous curative treatment for HNSCC and could be proposed systematically at 12 mo of the usual follow-up.

The aim of this retrospective multicentric study was to develop and evaluate a prognostic ¹⁸F-FDG PET/CT radiomic signature in early-stage non–small cell lung cancer patients treated with stereotactic body radiotherapy (SBRT). <b>Methods:</b> Patients from 3 different centers (<i>n</i> = 27, 29, and 8) were pooled to constitute the training set, whereas the patients from a fourth center (<i>n</i> = 23) were used as the testing set. The primary endpoint was local control. The primary tumor was semiautomatically delineated in the PET images using the fuzzy locally adaptive Bayesian algorithm, and manually in the low-dose CT images. In total, 184 Image Biomarkers Standardization Initiative–compliant radiomic features were extracted. Seven clinical and treatment parameters were included. We used ComBat to harmonize radiomic features extracted from the 4 institutions relying on different PET/CT scanners. In the training set, variables found significant in the univariate analysis were fed into a multivariate regression model, and models were built by combining independent prognostic factors. <b>Results:</b> Median follow-up was 21.1 mo (range, 1.7–63.4 mo) and 25.5 mo (range, 7.7–57.8 mo) in training and testing sets, respectively. In univariate analysis, none of the clinical variables, 2 PET features, and 2 CT features were significantly predictive of local control. The best predictive models in the training set were obtained by combining one feature from PET (Information Correlation 2) and one feature from CT (flatness), reaching a sensitivity of 100% and a specificity of 96%. Another model combining 2 PET features (Information Correlation 2 and strength) reached sensitivity of 100% and specificity of 88%, both with an undefined hazard ratio (<i>P</i> &lt; 0.001). The latter model obtained an accuracy of 0.91 (sensitivity, 100%; specificity, 81%), with a hazard ratio undefined (<i>P</i> = 0.023) in the testing set; however, other models relying on CT radiomic features only or the combination of PET and CT features failed to validate in the testing set. <b>Conclusion:</b> We showed that 2 radiomic features derived from ¹⁸F-FDG PET were independently associated with local control in patients with non–small cell lung cancer undergoing SBRT and could be combined in an accurate predictive model. This model could provide local relapse-related information and could be helpful in clinical decision making.

OBJECTIVE: The purpose of this prospective study was to compare the performance of (111)In-octreotide somatostatin receptor scintigraphy (SRS) and (18)fluorodesoxyglucose positron emission tomography (FDG-PET) in aggressive well-differentiated endocrine carcinoma (WDEC) defined by a high Ki67 (≥10%). METHODS: Eighteen consecutive patients explored in a single hospital between November 2003 and 2008 for high Ki67 (≥10%) WDEC were prospectively included. WDEC were sporadic in 17 cases and secreting in 16 cases. FDG-PET, SRS, and computed tomography (CT) were performed within a maximum of 3 months and reviewed by two independent readers. For each patient, an analysis per organ and lesion was performed. Both the results of conventional imaging and the highest number of metastatic organs and distinct lesions visualized by all imaging methods including SRS, FDG-PET, and thoraco-abdomino-pelvic CT were considered for the determination of the standard. Correlation between tumor slope and maximum standardized uptake value, Ki67 value, and grade of uptake at SRS was evaluated. RESULTS: FDG-PET, SRS, and CT showed at least one lesion in 18 (100%), 15 (83%), and 17 (94%) patients, respectively. A total of 254 lesions were diagnosed in 59 organs. FDG-PET, SRS, and CT detected 195 (77%), 109 (43%), and 195 (77%) lesions in 53 (90%), 30 (51%), and 39 (66%) organs, respectively. FDG-PET, compared to SRS, detected more, the same as, and less lesions in 14 (78%), one (6%), and three (17%) patients, respectively. A statistical trend was found between Ki67 value and tumor slope (P = 0.07). Median survival after diagnosis was 25 months (range, 6-71 months). CONCLUSION: These results suggest that FDG-PET is more sensitive than the SRS for high Ki67 WDEC staging.