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Background: Besides International Prognostic Index (IPI) score, baseline prognostic factors of post-transplant lymphoproliferative disorders (PTLD) are poorly identified due to the rarity of the disease. New indexes derived from healthy organ uptake in baseline 18F-FDG PET/CT have been studied in immunocompetent lymphoma patients. The aim of this study is to evaluate the performances of the cerebellum-to-liver uptake ratio (denoted as CLIP) as a prognostic factor for PFS and OS. This retrospective multicenter study is based on patients with PTLD included in the K-VIROGREF cohort. The previously published threshold of 3.24 was used for CLIP in these analyses., Results: A total of 97 patients was included with a majority of monomorphic diffuse large B-cell lymphoma subtype (78.3%). Both IPI score (≥ 3) and CLIP (< 3.24) were significant risk factors of PFS with corresponding hazard ratios of 2.0 (1.0-4.0) and 2.4 (1.3-4.5) respectively. For OS, CLIP was not significant and resulted in a hazard ratio of 2.6 (p = 0.059). Neither IPI score or Total Metabolic Tumor Volume reached significance for OS., Conclusion: CLIP is a promising predictor of PFS and perhaps OS in PTLD. Further prospective studies are needed to confirm these results., (© 2024. The Author(s).)

Post-transplant lymphoproliferative disorder (PTLD) is a rare complication of immunosuppression. Sequential treatment is commonly proposed, combining induction with rituximab (R-induction) followed by either continuation of treatment or addition of chemotherapy depending on response. Response to R-induction, often assessed by CT scan, is a major predictor of overall survival (OS). The aim of the study was to analyze predictive factors of R-induction response, including total metabolic tumor volume (TMTV), and investigate the role of 18 F-FDG PET/CT in response assessment. This retrospective multicenter study is based on patients with PTLD included in the K-VIROGREF cohort. Only patients treated by R-induction with a baseline 18 F-FDG PET/CT were included. Response to R-induction was assessed by 18 F-FDG PET/CT. The optimal threshold of TMTV for rituximab response was determined using receiver operating characteristic curves. Univariate and multivariate analyses were conducted to identify predictive factors of response. A total of 67 patients were included. Survival characteristics were similar to those previously reported: the complete response rate to R-induction was 30%, the 3-year OS estimate was 66%, and the treatment-related mortality was 4%. The optimal threshold for TMTV to predict R-induction response was 135 cm 3 . The response rate to R-induction was 38% in the 21 patients with TMTV ≥ 135 cm 3 and 72% in the 46 patients with TMTV < 135 cm 3 . TMTV was a significant predictor of response, both at univariate and multivariate analyses (odd ratios = 3.71, P = 0.022). Baseline TMTV is predictive of response to R-induction. Early assessment of patient response is feasible with 18 F-FDG PET/CT., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the European Hematology Association.)

Neuroendocrine neoplasms (NENs) are rare and heterogeneous epithelial tumors most commonly arising from the gastroenteropancreatic (GEP) system. GEP-NENs account for approximately 60% of all NENs, and the small intestine and pancreas represent two most common sites of primary tumor development. Approximately 80% of metastatic patients have secondary liver lesions, and in approximately 50% of patients, the liver is the only metastatic site. The therapeutic strategy depends on the degree of hepatic metastatic invasion, ranging from liver surgery or percutaneous ablation to palliative treatments to reduce both tumor volume and secretion. In patients with grade 1 and 2 NENs, locoregional nonsurgical treatments of liver metastases mainly include percutaneous ablation and endovascular treatments, targeting few or multiple hepatic metastases, respectively. In the present work, we provide a narrative review of the current knowledge on liver-directed therapy for metastasis treatment, including both interventional radiology procedures and nuclear medicine options in NEN patients, taking into account the patient clinical context and both the strengths and limitations of each modality.

Purpose: Thyroid nodules frequently coexist with primary hyperparathyroidism (pHPT). Because of the increasing use of 18F-fluorocholine (18F-FCH) PET/CT in patients with pHPT, evaluation of its clinical utility for thyroid nodules characterization in this population is of paramount importance. Herein, we investigate the value of dual-point 18F-FCH PET/CT in the diagnosis of thyroid cancer in patients referred for pHPT imaging who have thyroid nodules., Patients and Methods: All pHPT patients who underwent a dual-time point 18F-FCH PET/CT (at 5 and 60 minutes postinjection) between July 2019 and December 2020 were analyzed. Only those with a thyroid nodule greater than 10-mm and pathological analysis (criterion standard) were included. Nodule-to-thyroid SUVmax ratio was calculated at the 2 study points, as well as the 18F-FCH washout index (WO%)., Results: Twenty-seven patients (32 nodules) were included in this study. The final diagnoses were as follows: 27 benign nodules including 2 NIFTPs (noninvasive follicular thyroid neoplasm with papillary-like nuclear features) and 5 cancers of follicular origin. Early uptake ratio was significantly higher in malignant lesions than in benign nodules (P = 0.0008). Thyroid cancers were also characterized by a marked 18F-FCH washout index (WO% benign vs cancer: 2.9% ± 4.1% vs 45.5% ± 13.4%, P = 0.0001). Using a WO% threshold of 22.1%, 25/27 benign nodules and 5/5 malignant lesions were accurately classified (sensitivity of 100%, specificity of 92.6%, positive predictive value of 71.4%, and negative predictive value of 100%). The false-positive findings were related to the 2 NIFTPs that share similarities with thyroid cancer., Conclusions: Our preliminary results suggest to perform a dual-time-point PET/CT acquisition protocol in pHPT patients with uncharacterized centimeter thyroid nodules. However, the real impact of these promising results should be assessed by prospective studies on a larger cohort of patients., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Ventilation/perfusion lung scan is subject to blur due to respiratory motion whether with planar acquisition or single photon emission computed tomography (SPECT). We propose a data-driven gating method for extracting different respiratory phases from lung scan list-mode or dynamic data., Methods: The algorithm derives a surrogate respiratory signal from an automatically detected diaphragmatic region of interest. The time activity curve generated is then filtered using a Savitzky-Golay filter. We tested this method on an oscillating phantom in order to evaluate motion blur decrease and on one lung SPECT., Results: Our algorithm reduced motion blur on phantom acquisition: mean full width at half maximum 8.1 pixels on non-gated acquisition versus 5.3 pixels on gated acquisition and 4.1 pixels on reference image. Automated detection of the diaphragmatic region and time-activity curves generation were successful on patient acquisition., Conclusions: This algorithm is compatible with a clinical use considering its runtime. Further studies will be needed in order to validate this method.

Objective: To devise a simple PET-CT score for measurement of muscle disease activity in patients with inflammatory myopathies (IMs) and to assess its validity., Methods: A total of 44 PET-CT examinations in 34 IM patients (performed during cancer screening) and 20 PET-CT examinations in matched controls (investigated for pulmonary nodules with a conclusion of benignity) were analysed. Maximal standardized uptake values (SUVmax) were recorded bilaterally in eight proximal muscles. The muscle SUVmax (mSUVmax) was defined as the average of the 16 muscle SUVmax values, normalized on the liver mean SUV. Reliability, validity and responsiveness were evaluated., Results: The mSUVmax was increased in IM patients compared with controls. This index allowed the identification of patients with high vs low muscle disease activity using the myositis intention to treat activity index as the gold standard. In patients with subsequent examinations, our method showed good accuracy to detect changes in muscle disease activity [area under the curve 0.96 (95% CI 0.84, 1)]. Responsiveness was strong. Interrater reliability was excellent., Conclusion: PET-CT, a non-invasive tool useful for cancer screening, is also valuable to measure muscle disease activity and its evolution in IM patients., (© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

In this simulation study, we assessed differences in gross tumor volume (GTV) in a series of skull base paragangliomas (SBPGLs) using magnetic resonance imaging (MRI), 18 F-dihydroxyphenylalanine ( 18 F-FDOPA) combined positron emission tomography/computed tomography (PET/CT), and 18 F-FDOPA PET/MRI images obtained by rigid alignment of PET and MRI. GTV was delineated in 16 patients with SBPGLs on MRI (GTV MRI ), 18 F-FDOPA PET/CT (GTV PET ), and combined PET/MRI (GTV PET/MRI ). GTV PET/MRI was the union of GTV MRI and GTV PET after visual adjustment. Three observers delineated GTV MRI and GTV PET/MRI independently. Excellent interobserver reproducibility was found for both GTV MRI and GTV PET/MRI . GTV PET and GTV MRI were not significantly different. However, there was some spatial difference between the locations of GTV MRI , GTV PET , and GTV PET/MRI . The Dice similarity coefficient median value was 0.4 between PET/CT and MRI, and 0.8 between MRI and PET/MRI. The combined use of PET/MRI produced a larger GTV than MRI alone. Nevertheless, both the target-delivered dose and organs-at-risk conservancy were respected when treatment was planned on the PET/MRI-matched data set. Future integration of 18 F-FDOPA PET/CT into clinical practice will be necessary to evaluate the influence of this diagnostic modality on SBPGL therapeutic management. If the clinical utility of 18 F-FDOPA PET/CT and/or PET/MRI is confirmed, GTV PET/MRI should be considered for tailored radiotherapy planning in patients with SBPGL.

Purpose: Head and neck paragangliomas (HNPGLs) can relapse after primary treatment. Optimal imaging protocols have not yet been established for posttreatment evaluation. The aim of the present study was to assess the diagnostic value of 18 F-FDOPA PET/CT and MR/CT angiography (MRA/CTA) in HNPGL patients with clinical relapse during their follow-up., Methods: Sixteen consecutive patients presenting with local pain, tinnitus, dysphagia, hoarse voice, cranial nerve involvement, deafness, or retrotympanic mass appearing during follow-up after the initial treatment of HNPGLs were retrospectively evaluated. Patients underwent both 18 F-FDOPA PET/CT and MRA (15 patents) or CTA (1 patent). Both methods were first assessed under blinded conditions and afterwards correlated. Head and neck imaging abnormalities without histological confirmation were considered true-positive results based on a consensus between radiologists and nuclear physicians and on further 18 F-FDOPA PET/CT and/or MRA., Results: 18 F-FDOPA PET/CT and MRA/CTA were concordant in 14 patients and in disagreement in 2 patients. 18 F-FDOPA PET/CT and MRA/CTA identified, respectively, 12 and 10 presumed recurrent HNPGLs in 12 patients. The two lesions diagnosed by PET/CT only were confirmed during follow-up by otoscopic examination and MRA performed 29 and 17 months later. 18 F-FDOPA PET/CT images were only slightly influenced by the posttreatment sequelae, showing a better interobserver reproducibility than MRA/CTA. Finally, in 2 of the 16 studied patients, 18 F-FDOPA PET/CT detected two additional synchronous primary HNPGLs., Conclusion: 18 F-FDOPA PET/CT is highly sensitive in posttreatment evaluation of patients with HNPGLs, and also offers better interobserver reproducibility than MRA/CTA and whole-body examination. We therefore suggest that 18 F-FDOPA PET/CT is performed as the first diagnostic imaging modality in symptomatic patients with suspicion of HNPGL relapse after primary treatment when 68 Ga-labeled somatostatin analogues are not available.

Purpose: Infection and malignancy represent two common complications after solid organ transplantation, which are often characterized by poorly specific clinical symptomatology. Herein, we have evaluated the role of 18 F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) in this clinical setting., Methods: Fifty-eight consecutive patients who underwent FDG PET/CT after kidney, lung or heart transplantation were included in this retrospective analysis. Twelve patients underwent FDG PET/CT to strengthen or confirm a diagnostic suspicion of malignancies. The remaining 46 patients presented with unexplained inflammatory syndrome, fever of unknown origin (FUO), CMV or EBV seroconversion during post-transplant follow-up without conclusive conventional imaging. FDG PET/CT results were compared to histology or to the finding obtained during a clinical/imaging follow-up period of at least 6 months after PET/CT study., Results: Positive FDG PET/CT results were obtained in 18 (31 %) patients. In the remaining 40 (69 %) cases, FDG PET/CT was negative, showing exclusively a physiological radiotracer distribution. On the basis of a patient-based analysis, FDG PET/CT's sensitivity, specificity, PPV and NPV were respectively 78 %, 90 %, 78 % and 90 %, with a global accuracy of 86 %. FDG PET/CT was true positive in 14 patients with bacterial pneumonias (n = 4), pulmonary fungal infection (n = 1), histoplasmosis (n = 1), cutaneous abscess (n = 1), inflammatory disorder (sacroiliitis) (n = 1), lymphoma (n = 3) and NSCLC (n = 3). On the other hand, FDG PET/CT failed to detect lung bronchoalveolar adenocarcinoma, septicemia, endocarditis and graft-versus-host disease (GVHD), respectively, in four patients. FDG PET/CT contributed to adjusting the patient therapeutic strategy in 40 % of cases., Conclusions: FDG PET/CT emerges as a valuable technique to manage complications in the post-transplantation period. FDG PET/CT should be considered in patients with severe unexplained inflammatory syndrome or FUO and inconclusive conventional imaging or to discriminate active from silent lesions previously detected by conventional imaging particularly when malignancy is suspected.