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Purpose: Although ventilation/perfusion (V/Q) scintigraphy is a widely used imaging test, different options are possible for the acquisition and interpretation of the scan. The aim of this study was to assess current practices regarding the use and interpretation of lung scintigraphy in various clinical indications., Patients and Methods: An online survey comprising 25 questions was sent to nuclear medicine departments in Australia, Canada, France, Germany, and United States between 2022 and 2023. A single response per department was consolidated., Results: Four hundred nineteen responses were collected (Australia: 32, Canada: 58, France: 149, Germany: 92, and United States: 88). For acute pulmonary embolism (PE) diagnosis, 82.8% of centers reported using SPECT acquisitions (Australia: 93.3%, Canada: 91.8%, France: 99.2%, Germany: 96.2%, and United States: 32.1%). Among them, SPECT images were combined with a CT scan in 70.5% of centers. A total of 10.6% of centers reported not using ventilation for acute PE diagnosis. SPECT acquisition was used in 97.8% of centers using 99m Tc carbon particles, 97.1% 81m Kr gas, 58.7% 99m Tc-DTPA, and 19.4% 133 Xe gas, respectively. For V/Q SPECT interpretation, the EANM criteria were used in 65.0% of departments. A very wide variety of practices were observed in pregnant women and in COVID-19 patients. SPECT acquisition was widely used in the follow-up of PE and for the screening of chronic thromboembolic pulmonary hypertension (>90% of centers), with inconsistency regarding the interpretation of matched perfusion defects in this setting., Conclusions: This survey shows the strong adoption of SPECT in the various clinical indications of lung scintigraphy, except in the United States, where planar imaging is still mostly used. The survey also shows variability in interpretation criteria both for PE diagnosis and screening for chronic thromboembolic pulmonary hypertension, highlighting the need for further standardizations of practices., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Introduction: The pulmonary Hot Clot artifact (HCa) on 18F-FDG PET/CT is a poorly understood phenomenon, corresponding to the presence of a focal tracer uptake without anatomical lesion on combined CTscan. The hypothesis proposed in the literature is of microembolic origin. Our objectives were to determine the incidence of HCa, to analyze its characteristics and to identify associated factors., Methods: All 18F-FDG PET/CT retrieved reports containing the keywords (artifact/vascular adhesion/no morphological abnormality) during the period June 2021-2023 at Brest University Hospital were reviewed for HCa. Each case was associated with 2 control patients (same daily work-list). The anatomical and metabolic characteristics of HCa were analyzed. Factors related to FDG preparation/administration, patient and vascular history were investigated. Case-control differences between variables were tested using Chi-2 test and OR (qualitative) or Student's t-test (quantitative)., Results: Of the 22,671 18F-FDG PET/CT performed over 2 years, 211 patients (0.94%) showed HCa. The focus was single in 97.6%, peripheral in 75.3%, and located independently in the right or left lung (51.1% vs. 48.9%). Mean ± SD values for SUVmax, SUVmean, MTV and TLG were 11.3 ± 16.5, 5.1 ± 5.0, 0.3 ± 0.3 ml and 1.5 ± 2.1 g respectively. The presence of vascular adhesion (p < 0.001), patient age (p = 0.002) and proximal venous access (p = 0.001) were statistically associated with the presence of HCa., Conclusion: HCa is a real but rare phenomenon (incidence around 1%), mostly unique, intense, small in volume (< 1 ml), and associated with the presence of vascular FDG uptake, confirming the hypothesis of a microembolic origin due to probable vein wall trauma at the injection site., (© 2024. The Author(s).)

Head and neck squamous cell carcinoma (HNSCC) remains a malignancy with high rates of locoregional recurrence and poor prognosis for recurrent cases. Early detection of subclinical lesions is challenging but critical for effective patient management. Imaging surveillance after treatment, particularly 18 F-FDG PET/CT, has shown promise in the diagnosis of HNSCC recurrence. The aim was to evaluate the diagnostic performance of 18 F-FDG PET/CT according to delay after treatment in detecting subclinical recurrence (SCR) in HNSCC patients. Methods: In this retrospective study, all 18 F-FDG PET/CT scans were performed at a single center. All adults with histologically proven HNSCC who were treated with curative intent between January 1, 2006, and December 31, 2021, were included. They had a normal clinical examination before each scan. Patients who underwent an intensive follow-up strategy after treatment had 18 F-FDG PET/CT with an intravenous contrast agent at 3-6 mo and annually thereafter for 5 y. The primary endpoint was diagnostic performance (positive and negative predictive values, sensitivity, specificity, and accuracy). Results: In total, 2,566 18 F-FDG PET/CT scans were performed among 852 patients, with an average of 3 scans per patient. The overall diagnostic performance measures were as follows: positive predictive value (88%), negative predictive value (98%), sensitivity (98%), specificity (89%), and accuracy (93%). There were no significant differences in diagnostic performance over time. The scans detected 126 cases of SCR (14.8%) and 118 cases of metachronous cancer (13.8%). The incidence of SCR decreased over time, with the highest detection rate in the first 2 y after treatment. Positive predictive value improved over time, reaching 90% for the digital Vision 600 system (third period) compared with 76% for the analog Gemini GXLi system (first period, P < 0.001). Multivariate analysis identified advanced stage, high body mass index, and initial PET/CT upstaging as predictive factors for detection of SCR. Conclusion: Our study demonstrates that 18 F-FDG PET/CT has high diagnostic performance in detecting SCR during follow-up after treatment of HNSCC, especially in the first 2 y. Advanced tumor stage, initial PET/CT upstaging, and high body mass index were associated with a higher likelihood of SCR detection. The routine use of 18 F-FDG PET/CT during follow-up seems justified for patients with HNSCC., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Introduction: Pulmonary embolism (PE) is a challenge to diagnose and when missed, exposes patients to potentially fatal recurrent events. Beyond CT pulmonary angiography (CTPA) and planar ventilation/perfusion (V/Q) scan, single photon emission CT (SPECT) V/Q emerged a new diagnostic modality of scintigraphic acquisition that has been reported to improve diagnostic performances. To date, no management outcome study or randomised trial evaluated an algorithm based on SPECT V/Q for PE diagnosis. We present the design of a randomised multicentre, international management study comparing SPECT V/Q with validated strategies., Material and Methods: We will include a total of 3672 patients with suspected PE requiring chest imaging, randomised into three different groups, each using a different diagnostic strategy based on SPECT V/Q, CTPA and planar V/Q scan. Randomisation will be unbalanced (2:1:1), with twice as many patients in SPECT V/Q arm (n=1836) as in CTPA and planar V/Q arms (n=918 in each). Our primary objective will be to determine whether a diagnostic strategy based on SPECT V/Q is non-inferior to previously validated strategies in terms of diagnostic exclusion safety as assessed by the 3-month risk of thromboembolism in patients with a negative diagnostic workup. Secondary outcomes will be the proportion of patients diagnosed with PE in each arm, patients requiring additional tests, the incidence of major and clinically relevant non-major bleeding and the incidence and cause of death in each arm., Ethics and Dissemination: This trial is funded by a grant from Brest University Hospital and by INVENT. The study protocol was approved by Biomedical Research Ethics Committee. The investigator or delegate will obtain signed informed consent from all patients prior to inclusion in the trial. Our results will inform future clinical practice guidelines and solve the current discrepancy between nuclear medicine guidelines and clinical scientific society guidelines., Trial Registration Number: NCT02983760., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The primary objective of the present study was to identify a subset of radiomic features extracted from primary tumor imaged by computed tomography of early-stage non-small cell lung cancer patients, which remain unaffected by variations in segmentation quality and in computed tomography image acquisition protocol. The robustness of these features to segmentation variations was assessed by analyzing the correlation of feature values extracted from lesion volumes delineated by two annotators. The robustness to variations in acquisition protocol was evaluated by examining the correlation of features extracted from high-dose and low-dose computed tomography scans, both of which were acquired for each patient as part of the stereotactic body radiotherapy planning process. Among 106 radiomic features considered, 21 were identified as robust. An analysis including univariate and multivariate assessments was subsequently conducted to estimate the predictive performance of these robust features on the outcome of early-stage non-small cell lung cancer patients treated with stereotactic body radiation therapy. The univariate predictive analysis revealed that robust features demonstrated superior predictive potential compared to non-robust features. The multivariate analysis indicated that linear regression models built with robust features displayed greater generalization capabilities by outperforming other models in predicting the outcomes of an external validation dataset., (© 2024. The Author(s).)

Purpose: Evaluate the benefit of 2-deoxy-2-[18F]-fluoro-D-glucose ([ 18 F] FDG) positron emission tomography/computed tomography (PET/CT) for the therapeutic assessment of Abatacept (ABA) as first-line therapy in early-onset polymyalgia rheumatica (PMR) patients., Methods: This was an ancillary study of ALORS trial (Abatacept in earLy Onset polymyalgia Rheumatica Study) assessing the ability of ABA versus placebo to achieve low disease activity (C-Reactive Protein PMR activity score (CRP PMR-AS) ≤ to 10) without glucocorticoid (GC) at week 12 in patients with early-onset PMR. The patients underwent [ 18 F] FDG PET/CT at baseline and after 12 weeks of treatment. Responses to treatments were evaluated according to CRP PMR-AS, Erythrocyte Sedimentation Rate (ESR) PMR-AS, Clin PMR-AS, and CRP-Imputed (Imput-CRP) PMR-AS. Quantitative score by maximal standardized uptake value (SUVmax) and combined qualitative scores according to liver uptake (Leuven, Leuven/Groningen, and Besançon Scores) were used for assessment of [ 18 F] FDG uptake in regions of interest (ROI) usually affected in PMR. Student's t-test was applied to evaluate the clinical, biological, and [ 18 F] FDG uptake variation difference in ABA and placebo groups between W0 and W12. Subgroup analysis by GC rescue was performed., Results: At W12, there was no significant difference according to SUVmax between the ABA and the placebo groups in all ROI. Subgroup analysis according to GC administration demonstrated a significant (p 0.047) decrease in SUVmax within the left sternoclavicular joint ROI in the ABA group (- 0.8) compared to the placebo group (+ 0.6) without GC rescue. Other results did not reveal any significant difference between the ABA and placebo groups. According to combined qualitative scores, there was no significant difference between ABA and placebo groups for the direct comparison analysis and subgroup analysis according to GC rescue., Conclusion: [ 18 F] FDG PET/CT uptake did not decrease significantly after ABA compared to placebo in anatomical areas usually affected in PMR patients. These results are correlated with the clinical-biological therapeutic assessment., Clinical Trial Registration: The study was approved by the appropriate ethics committee (CPP Sud-Est II Ref CPP: 2018-33), and all patients gave their written informed consent before study enrollment. The protocol was registered on Clinicaltrials.gov (NCT03632187)., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To develop machine learning models to predict regional and/or distant recurrence in patients with early-stage non-small cell lung cancer (ES-NSCLC) after stereotactic body radiation therapy (SBRT) using [ 18 F]FDG PET/CT and CT radiomics combined with clinical and dosimetric parameters., Methods: We retrospectively collected 464 patients (60% for training and 40% for testing) from University Hospital of Liège and 63 patients from University Hospital of Brest (external testing set) with ES-NSCLC treated with SBRT between 2010 and 2020 and who had undergone pretreatment [ 18 F]FDG PET/CT and planning CT. Radiomic features were extracted using the PyRadiomics toolbox®. The ComBat harmonization method was applied to reduce the batch effect between centers. Clinical, radiomic, and combined models were trained and tested using a neural network approach to predict regional and/or distant recurrence., Results: In the training (n = 273) and testing sets (n = 191 and n = 63), the clinical model achieved moderate performances to predict regional and/or distant recurrence with C-statistics from 0.53 to 0.59 (95% CI, 0.41, 0.67). The radiomic (original&#95;firstorder&#95;Entropy, original&#95;gldm&#95;LowGrayLevelEmphasis and original&#95;glcm&#95;DifferenceAverage) model achieved higher predictive ability in the training set and kept the same performance in the testing sets, with C-statistics from 0.70 to 0.78 (95% CI, 0.63, 0.88) while the combined model performs moderately well with C-statistics from 0.50 to 0.62 (95% CI, 0.37, 0.69)., Conclusion: Radiomic features extracted from pre-SBRT analog and digital [ 18 F]FDG PET/CT outperform clinical parameters in the prediction of regional and/or distant recurrence and to discuss an adjuvant systemic treatment in ES-NSCLC. Prospective validation of our models should now be carried out., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: The aim was to investigate the feasibility of a shortened dynamic whole-body (dWB) FDG-PET/CT protocol and Patlak imaging using a population-based input function (PBIF), instead of an image-derived input function (IDIF) across the 60-min post-injection period, and study its effect on the FDG influx rate (Ki) quantification in patients with metastatic melanoma (MM) undergoing immunotherapy., Methods: Thirty-seven patients were enrolled, including a PBIF modeling group (n = 17) and an independent validation cohort (n = 20) of MM from the ongoing prospective IMMUNOPET2 trial. All dWB-PET data were acquired on Vision 600 PET/CT systems. The PBIF was fitted using a Feng's 4-compartments model and scaled to the individual IDIF tail's section within the shortened acquisition time. The area under the curve (AUC) of PBIFs was compared to respective IDIFs AUC within 9 shortened time windows (TW) in terms of linear correlation (R 2 ) and Bland-Altman tests. Ki metrics calculated with PBIF vs IDIF on 8 organs with physiological tracer uptake, 44 tumoral lesions of MM and 11 immune-induced inflammatory sites of pseudo-progression disease were also compared (Mann-Whitney test)., Results: The mean ± SD relative AUC bias was calculated at 0.5 ± 3.8% (R 2  = 0.961, AUC PBIF  = 1.007 × AUC IDIF ). In terms of optimal use in routine practice and statistical results, the 5th-7th pass (R 2  = 0.999 for both Ki mean and Ki max) and 5th-8th pass (mean ± SD bias = - 4.9 ± 6.5% for Ki mean and - 4.8% ± 5.6% for Ki max) windows were selected. There was no significant difference in Ki values from PBIF 5&#95;7 vs IDIF 5&#95;7 for physiological uptakes (p > 0.05) as well as for tumor lesions (mean ± SD Ki IDIF 5&#95;7 3.07 ± 3.27 vs Ki PBIF 5&#95;7 2.86 ± 2.96 100ml/ml/min, p = 0.586) and for inflammatory sites (mean ± SD Ki IDIF 5&#95;7 1.13 ± 0.59 vs Ki PBIF 5&#95;7 1.13 ± 0.55 100ml/ml/min, p = 0.98)., Conclusion: Our study showed the feasibility of a shortened dWB-PET imaging protocol with a PBIF approach, allowing to reduce acquisition duration from 70 to 20 min with reasonable bias. These findings open perspectives for its clinical use in routine practice such as treatment response assessment in oncology., (© 2023. The Author(s).)

Objective: Hypothyroidism is the most common complication of hemithyroidectomy for thyroid nodules. This retrospective cohort study investigated the prognostic factors for hypothyroidism following hemithyroidectomy., Methods: We included patients who underwent hemithyroidectomy between 2016 and 2017, excluding those with history of preoperative hypothyroidism or malignancy on histopathological examination. The primary endpoint was development of hypothyroidism during follow-up (TSH≥2 above normal)., Results: Twenty-six of the 128 included patients (20%) developed postoperative hypothyroidism. The following independent prognostic factors were found: preoperative TSH level>1.5 mIU/L (OR 2.11; P=0.013), and remaining thyroid volume adjusted for body surface area<4.0mL/m 2 (OR 1.77; P=0.015). Twenty-one patients (81%) had first TSH values above the upper limit of normal. Postoperatively, first TSH level correlated significantly with the preoperative value (R=0.5779, P<0.001). Levothyroxine was prescribed to 16% of patients, with a mean dose of 0.92μg/kg/day., Conclusion: Patients with TSH>1.5 mIU/or remaining thyroid volume adjusted for body surface area<4.0mL/m 2 should have intensified clinical and biological follow-up in the first year after surgery., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)

In this article the technique, interpretation, and diagnostic performance of scintigraphy for the diagnosis of acute pulmonary embolism (PE) are reviewed. Lung scintigraphy has stood the test of time as a reliable and validated examination for the determination of PE. Ventilation/perfusion (V/Q) lung scintigraphy assesses the functional consequences of the clot on its downstream vascular bed in conjunction with the underlying ventilatory status of the affected lung region, in contrast to CT pulmonary angiography (CTPA), which visualizes presence of the clot within affected vessels. Most-commonly used ventilation radiopharmaceuticals are Technetium-99m labeled aerosols (such as 99m Technetium-DTPA), or ultrafine particle suspensions ( 99m Tc-Technegas) which reach the distal lung in proportion to regional distribution of ventilation. Perfusion images are obtained after intravenous administration 99m Tc-labeled macro-aggregated albumin particles which lodge in the distal pulmonary capillaries. Both planar and tomographic methods of imaging, each favored in different geographical regions, will be described. Guidelines for interpretation of scintigraphy have been issues by both the Society of Nuclear Medicine and Molecular Imaging, and by the European Association of Nuclear Medicine. Breast tissue is particularly radiosensitive during pregnancy due to its highly proliferative state and many guidelines recommend use of lung scintigraphy rather than CTPA in this population. Several maneuvers are available in order to further reduce radiation exposure including reducing radiopharmaceutical dosages or omitting ventilation altogether, functionally converting the study to a low-dose screening examination; if perfusion defects are present, further testing is necessary. Several groups have also performed perfusion-only studies during the COVID epidemic in order to reduce risk of respiratory contagion. In patients where perfusion defects are present, further testing is again necessary to avoid false-positive results. Improved availability of personal protective equipment, and reduced risk of serious infection, have rendered this maneuver moot in most practices. First introduced 60 years ago, subsequent advances in radiopharmaceutical development and imaging methods have positioned lung scintigraphy to continue to play an important clinical and research role in the diagnosis of acute PE., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Importance: Patients with head and neck squamous cell carcinoma (HNSCC) have a significant risk of locoregional recurrence within the first 2 years, with approximately two-thirds of patients experiencing such recurrence. While early recurrence detection may be associated with improved patient outcomes, the association of such detection with survival remains uncertain., Objective: To investigate the association of an intensive posttreatment follow-up strategy using 18F-fludeoxyglucose-positron emission tomography with computed tomography (18FDG-PET/CT) with survival among patients with HNSCC., Design, Setting, and Participants: This case-control study was conducted among patients treated at 1 of 3 locations in Brest, France (University Hospital, Military Hospital, or Pasteur Clinic). The statistical analysis was conducted from January to June 2023. All adults with histologically proven HNSCC who were treated with curative intent between January 1, 2006, and December 31, 2019, and achieved a complete response on imaging at 3 to 6 months were included. They had a minimum of 3 years of follow-up., Exposures: Patients undergoing an intensive posttreatment follow-up strategy had 18FDG-PET/CT (PET/CT group) at months 12, 24, and 36, chosen at the discretion of ear, nose, and throat surgeons., Main Outcomes and Measures: Overall survival (OS) at 3 years., Results: Among 782 patients with HNSCC (642 males [82.1%]; median [IQR] age, 61 [56-68] years), 497 patients had 18FDG-PET/CT during follow-up and 285 patients had conventional follow-up (CFU group). Cox regression analysis showed an association between undergoing 18FDG-PET/CT and lower risk of death (odds ratio, 0.71; 95% CI, 0.57-0.88; P = .002) after adjustment for covariates (age, sex, comorbidities, primary location, stage, surgeon, year of treatment, and treatment). The mean (SD) 3-year OS was significantly better in the PET/CT vs CFU group (72.5% [2.0%] vs 64.3% [2.9%]; P = .002). Analysis based on American Joint Committee on Cancer stage showed significantly better mean (SD) 3-year OS for advanced stages III and IV in the PET/CT group (373 patients) vs CFU group (180 patients; 68.5% [2.4%] vs 55.4% [3.8%]; P < .001), while no significant difference was observed between patients with stage I or II HNSCC. Analysis based on primary tumor site revealed significantly longer mean (SD) 3-year OS for oropharyngeal tumor in the PET/CT group (176 patients) than the CFU group (100 patients; 69.9% [3.5%] vs 60.5% [5.0%]; P = .04)., Conclusions and Relevance: This case-control study found that use of 18FDG-PET/CT in the standard annual CFU of HNSCC was associated with a 3-year survival benefit, with a larger benefit for patients with advanced initial tumor stage (III-IV) and oropharyngeal disease.

We aimed to assess the relationship between residual pulmonary vascular obstruction (RPVO) on planar lung scan after completion of at least 3 months of anticoagulant therapy for acute pulmonary embolism (PE) and the risk of recurrent venous thromboembolism (VTE) or death due to PE one year after treatment discontinuation. The systematic review was registered with the International Prospective Registry of Systematic Reviews (PROSPERO: CRD42017081080). The primary outcome measure was to generate a pooled estimate of the rate of recurrent VTE at one year in patient with RPVO diagnosed on planar lung scan after discontinuation of at least 3 months of anticoagulant treatment for an acute PE. Individual data were obtained for 809 patients. RPVO (ie, obstruction >0%) was found in 407 patients (50.3%) after a median of 6.6 months of anticoagulant therapy for a first acute PE. Recurrent VTE or death due to PE occurred in 114 patients (14.1%), for an annual risk of 6.4% (95% confidence interval, 4.7%-8.6%). Out of the 114 recurrent events, 63 occurred within one year after discontinuation of anticoagulant therapy corresponding to a risk of 8.1% (6.4%-9.8%) at 1 year. The risk of recurrent VTE at one year was 5.8% (4.4-7.2) in participants with RPVO <5%, vs 11.7% (9.5-13.8) in participants with RPVO ≥5%. RPVO is a significant predictor of the risk of recurrent venous thromboembolism. However, the risk of recurrent events remains too high in patients without residual perfusion defect for it to be used as a stand-alone test to decide on anticoagulation discontinuation., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Introduction: Prostate adenocarcinoma (CaP) is the leading cancer in men. After curative treatment, from 27% to 53% of patients will experience biochemical recurrence (BR). With the development of focal therapies, precise early identification of recurrence's sites is of utmost importance in order to deliver individualized treatment on positive lesions. The aim of this study was to assess the detection rate (DR) of 68 Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) in selected patients with prostate cancer BR and recent negative 18 F-choline PET/CT., Patients and Methods: We performed a retrospective analysis including all patients with CaP referred for BR with a negative 18 F-choline PET/CT, and who underwent 68 Ga-PSMA-11 PET/CT between October, 2018 and December, 2019. The overall DR of 68 Ga-PSMA-11 PET/CT was calculated, and described according to BR characteristics especially PSA levels and velocity. Patients were followed up for at least 1 year. Patient management following 68 Ga-PSMA-11 PET/CT and PSA levels evolution after treatment were also recorded., Results: One hundred fifty-nine patients comprising 164 examinations were analyzed. The overall DR of 68 Ga-PSMA-11 PET/CT for BR was 65.9% (95CI, 58.6-73.1). The DR was 52.5% (95CI, 39.9-65.0), 70.6% (95CI, 55.3-85.9), 70.4% (95CI, 53.1-87.6), and 78.6% (95CI, 66.2-91.0) for PSA levels between 0.2 and 0.49 ng/mL, 0.5 to 0.99 ng/mL, 1 to 1.99 ng/mL and PSA ≥ 2 ng/mL, respectively. The DR was 70.7% (95CI, 59.0-82.4) with a PSA doubling time (PSA-DT) ≤6 months and 65.2% (95CI, 55.5-74.9) with a PSA-DT >6 months. Around 3/4 of patients (75.9%) with a positive 68 Ga-PSMA-11 PET/CT initiated treatment, including surgery (2.4%), stereotactic radiotherapy ± androgen deprivation therapy (ADT) (22%) or external conformational radiotherapy ± ADT (46.3%). Patient management changed in 43 cases (39.8%)., Conclusion: Our study confirmed the ability of 68 Ga-PSMA-11 PET/CT to detect occult biochemical recurrence, even in a selected population of CaP patients with negative 18 F-choline PET/CT, even at low PSA levels., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Introduction: Quantifying the pulmonary vascular obstruction index (PVOI) is essential for the management of patients with pulmonary embolism or chronic thromboembolic pulmonary hypertension (CTEPH). The reference method for quantifying the PVOI with planar lung ventilation/perfusion (V/Q) scintigraphy is the Meyer score, which was validated using pulmonary angiography as a reference standard. However, it is complex to use in daily practice. In contrast, a rapid and fast quantification method consists in estimating the PVOI based on the number of segmental perfusion defects. However, the accuracy of this method has never been evaluated. In this study, we aimed to compare PVOI quantification on planar V/Q scintigraphy assessed by a segmental visual scoring (SVS) to the Meyer score., Materials and Methods: The eligible study population consisted of consecutive patients who underwent planar V/Q scan for CTEPH screening. A central review was performed by three nuclear medicine physicians. PVOI was assessed by summing the number of segmental perfusion defects or equivalent (2 sub-segments = 1 segment = 5%) and by Meyer's method. The two interpretations were performed 6 months apart. A Spearman rank correlation coefficient was calculated to evaluate correlation between the two measurement methods. An intra-class correlation (ICC) was calculated to assess agreement. A Bland et Altman plot analysis was used to evaluate agreement between the two measurements., Results: A total of 226 V/Q scans were interpreted. Spearman rank correlation coefficient between SVS and Meyer was 0.963 (95%CI 0.952-0.971) for mismatched perfusion defects and 0.963 (95%CI 0.953-0.972) for perfusion defects regardless of ventilation. Intra-class correlation (ICC) for agreement was 0.978 (95%CI 0.972-0.983) for mismatched perfusion defects and 0.968 (95%CI 0.959-0.976) for perfusion defects regardless of ventilation. In Bland & Altmann analysis, the mean difference between the SVS method and the Meyer score was 0.42 and 0.61 for the mismatched or matched evaluation, respectively., Conclusion: Our study shows a high correlation, and low differences in PVOI quantification when using a segmental visual scoring (SVS) as compared to the Meyer score. The SVS has the great advantage to be easy and rapid to apply in daily practice., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Le Pennec, Tromeur, Orione, Robin, Le Mao, Gut-Gobert, Le Gal, Salaün and Le Roux.)

Rational: To validate a population-based input function (PBIF) model that alleviates the need for scanning since injection time in dynamic whole-body (WBdyn) PET., Methods: Thirty-seven patients with suspected/known well-differentiated neuroendocrine tumors were included (GAPETNET trial NTC03576040). All WBdyn 68Ga-DOTATOC-PET/CT acquisitions were performed on a digital PET system (one heart-centered 6 min-step followed by nine WB-passes). The PBIF model was built from 20 image-derived input functions (IDIFs) obtained from a respective number of patients' WBdyn exams using an automated left-ventricle segmentation tool. All IDIF peaks were aligned to the median time-to-peak, normalized to patient weight and administrated activity, and then fitted to an exponential model function. PBIF was then applied to 17 independent patient studies by scaling it to match the respective IDIF section at 20-55 min post-injection time windows corresponding to WB-passes 3-7. The ratio of area under the curves (AUCs) of IDIFs and PBIF 3-7 were compared using a Bland-Altman analysis (mean bias ± SD). The Patlak-estimated mean Ki for physiological uptake (Ki-liver and Ki-spleen) and tumor lesions (Ki-tumor) using either IDIF or PBIF were also compared., Results: The mean AUC ratio (PBIF/IDIF) was 0.98 ± 0.06. The mean Ki bias between PBIF 3-7 and IDIF was -2.6 ± 6.2% (confidence interval, CI: -5.8; 0.6). For Ki-spleen and Ki-tumor, low relative bias with low SD were found [4.65 ± 7.59% (CI: 0.26; 9.03) and 3.70 ± 8.29% (CI: -1.09; 8.49) respectively]. For Ki-liver analysis, relative bias and SD were slightly higher [7.43 ± 13.13% (CI: -0.15; 15.01)]., Conclusion: Our study showed that the PBIF approach allows for reduction in WBdyn DOTATOC-PET/CT acquisition times with a minimum gain of 20 min., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2022 Thuillier, Bourhis, Pavoine, Metges, Le Pennec, Schick, Blanc-Béguin, Hennebicq, Salaun, Kerlan, Karakatsanis and Abgral.)

Objective: The diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH) is a major challenge as it is a curable cause of pulmonary hypertension (PH). Ventilation/Perfusion (V/Q) lung scintigraphy is the imaging modality of choice for the screening of CTEPH. However, there is no consensus on the criteria to use for interpretation. The aim of this study was to assess the accuracy of various interpretation criteria of planar V/Q scintigraphy for the screening of CTEPH in patients with PH., Methods: The eligible study population consisted of consecutive patients with newly diagnosed PH in the Brest University Hospital, France. Final diagnosis (CTEPH or non-CTEPH) was established in a referential center on the management of PH, based on the ESC/ERS guidelines and a minimum follow-up of 3 years. A retrospective central review of planar V/Q scintigraphy was performed by three nuclear physicians blinded to clinical findings and to final diagnosis. The number, extent (sub-segmental or segmental) and type (matched or mismatched) of perfusion defects were reported. Sensitivity and specificity were evaluated for various criteria based on the number of mismatched perfusion defects and the number of perfusion defects (regardless of ventilation). Receiver operating characteristic (ROC) curves were generated and areas under the curve (AUC) were calculated for both., Results: A total of 226 patients with newly diagnosed PH were analyzed. Fifty six (24.8%) were diagnosed with CTEPH while 170 patients (75.2%) were diagnosed with non-CTEPH. The optimal threshold was 2.5 segmental mismatched perfusion defects, providing a sensitivity of 100 % (95% CI 93.6-100%) and a specificity of 94.7% (95%CI 90.3-97.2%). Lower diagnostic cut-offs of mismatched perfusion defects provided similar sensitivity but lower specificity. Ninety five percent of patients with CTEPH had more than 4 segmental mismatched defects. An interpretation only based on perfusion provided similar sensitivity but a specificity of 81.8% (95%CI 75.3-86.9%)., Conclusion: Our study confirmed the high diagnostic performance of planar V/Q scintigraphy for the screening of CTEPH in patients with PH. The optimal diagnostic cut-off for interpretation was 2.5 segmental mismatched perfusion defects. An interpretation only based on perfusion defects provided similar sensitivity but lower specificity., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Le Pennec, Tromeur, Orione, Robin, Le Mao, De Moreuil, Jevnikar, Hoffman, Savale, Couturaud, Sitbon, Montani, Jaïs, Le Gal, Salaün, Humbert and Le Roux.)

Background: The use of 18FDG-PET/CT for delineating a gross tumor volume (GTV, also called MTV metabolic tumor volume) in radiotherapy (RT) planning of head neck squamous cell carcinomas (HNSCC) is not included in current recommendations, although its interest for the radiotherapist is of evidence. Because pre-RT PET scans are rarely done simultaneously with dosimetry CT, the validation of a robust image registration tool and of a reproducible MTV delineation method is still required., Objective: Our objective was to study a CT-based elastic registration method on dual-time pre-RT 18FDG-PET/CT images to assess the feasibility of PET-based RT planning in patients with HNSCC., Methods: Dual-time 18FDG-PET/CT [whole-body examination (wbPET) + 1 dedicated step (headPET)] were selected to simulate a 2-times scenario of pre-RT PET images deformation on dosimetry CT. ER-headPET and RR-headPET images were, respectively, reconstructed after CT-to-CT rigid (RR) and elastic (ER) registrations of the headPET on the wbPET. The MTVs delineation was performed using two methods (40%SUVmax, PET-Edge). The percentage variations of several PET parameters (SUVmax, SUVmean, SUVpeak, MTV, TLG) were calculated between wbPET, ER-headPET, and RR-headPET. Correlation between MTV values was calculated (Deming linear regression). MTVs intersections were assessed by two indices (OF, DICE) and compared together (Wilcoxon test). Additional per-volume analysis was evaluated (Mann-Whitney test). Inter- and intra-observer reproducibilities were evaluated (ICC = intra-class coefficient)., Results: 36 patients (30M/6F; median age = 65 y) were retrospectively included. The changes in SUVmax, SUVmean and SUVpeak values between ER-headPET and RR-headPET images were <5%. The variations in MTV values between ER-headPET and wbPET images were -6 and -3% with 40%SUVmax and PET Edge, respectively. Their correlations were excellent whatever the delineation method (R 2 > 0.99). The ER-headPET MTVs had significant higher mean OF and DICE with the wbPET MTVs, for both delineation methods ( p ≤ 0.002); and also when lesions had a volume > 5cc (excellent OF = 0.80 with 40%SUVmax). The inter- and intra-observer reproducibilities for MTV delineation were excellent (ICC ≥ 0.8, close to 1 with PET-Edge)., Conclusion: Our study demonstrated no significant changes in MTV after an elastic deformation of pre-RT 18FDG-PET/CT images acquired in dual-time mode. This opens possibilities for HNSCC radiotherapy planning improvement by transferring GTV-PET on dosimetry CT., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Maajem, Leclère, Bourhis, Tissot, Icard, Arnaud, Le Pennec, Dissaux, Gujral, Salaün, Schick and Abgral.)

Background: In patients with pulmonary embolism (PE), there is a growing interest in quantifying the pulmonary vascular obtruction index (PVOI), which may be an independent risk factor for PE recurrence. Perfusion SPECT/CT is a very attractive tool to provide an accurate quantification of the PVOI. However, there is currently no reliable method to automatically delineate and quantify it. The aim of this phantom study was to assess and compare 3 segmentation methods for PVOI quantification with perfusion SPECT/CT imaging., Methods: Three hundred ninety-six SPECT/CT scans, with various PE scenarios (n = 44), anterior to posterior perfusion gradients (n = 3), and lung volumes (n = 3) were simulated using Simind software. Three segmentation methods were assesssed: (1) using an intensity threshold expressed as a percentage of the maximal voxel value (MaxTh), (2) using a Z-score threshold (ZTh) after building a Z-score parametric lung map, and (3) using a relative difference threshold (RelDiffTh) after building a relative difference parametric map. Ninety randomly selected simulations were used to define the optimal threshold, and 306 simulations were used for the complete analysis. Spacial correlation between PE volumes from the phantom data and the delineated PE volumes was assessed by computing DICE PE indices. Bland-Altman statistics were used to calculate agreement for PVOI between the phantom data and the segmentation methods., Results: Mean DICE PE index was higher with the RelDiffTh method (0.85 ± 0.08), as compared with the MaxTh method (0.78 ± 0.16) and the ZTh method (0.67 ± 0.15). Using the RelDiffTh method, mean DICE PE index remained high (> 0.81) regardless of the perfusion gradient and the lung volumes. Using the RelDiffTh method, mean relative difference in PVOI was - 12%, and the limits of agreement were - 40% to 16%. Values were 3% (- 75% to 81%) for MaxTh method and 0% (- 120% to 120%) for ZTh method. Graphycal analysis of the Bland-Altman graph for the RelDiffTh method showed very close estimation of the PVOI for small and medium PE, and a trend toward an underestimation of large PE., Conclusion: In this phantom study, a delineation method based on a relative difference parametric map provided a good estimation of the PVOI, regardless of the extent of PE, the intensity of the anterior to posterior gradient, and the whole lung volumes.

To present the feasibility of a dynamic whole-body (DWB) 68 Ga-DOTATOC-PET/CT acquisition in patients with well-differentiated neuroendocrine tumors (WD-NETs). Sixty-one patients who underwent a DWB 68 Ga-DOTATOC-PET/CT for a histologically proven/highly suspected WD-NET were prospectively included. The acquisition consisted in single-bed dynamic acquisition centered on the heart, followed by the DWB and static acquisitions. For liver, spleen and tumor (1-5/patient), Ki values (in ml/min/100 ml) were calculated according to Patlak's analysis and tumor-to-liver (TLR-Ki) and tumor-to-spleen ratios (TSR-Ki) were recorded. Ki-based parameters were compared to static parameters (SUVmax/SUVmean, TLR/TSRmean, according to liver/spleen SUVmean), in the whole-cohort and according to the PET system (analog/digital). A correlation analysis between SUVmean/Ki was performed using linear and non-linear regressions. Ki-liver was not influenced by the PET system used, unlike SUVmax/SUVmean. The regression analysis showed a non-linear relation between Ki/SUVmean (R 2  = 0.55,0.68 and 0.71 for liver, spleen and tumor uptake, respectively) and a linear relation between TLRmean/TLR-Ki (R 2  = 0.75). These results were not affected by the PET system, on the contrary of the relation between TSRmean/TSR-Ki (R 2  = 0.94 and 0.73 using linear and non-linear regressions in digital and analog systems, respectively). Our study is the first showing the feasibility of a DWB 68 Ga-DOTATOC-PET/CT acquisition in WD-NETs.

Objectives: 68 Ga Ventilation/Perfusion V/Q PET-CT is a promising imaging tool for pulmonary embolism diagnosis. However, no study has verified whether the interpretation is reproducible between different observers. The aim of this study was to assess the interobserver agreement in the interpretation of V/Q PET-CT for the diagnosis of acute PE, and to compare it to the interobserver agreement of CTPA interpretation. Methods: Twenty-four cancer patients with suspected acute PE underwent V/Q PET-CT and CTPA within 24 h as part of a prospective pilot study evaluating V/Q PET-CT for the management of patients with suspected PE. V/Q PET-CT and CTPA scans were reassessed independently by four nuclear medicine physicians and four radiologists, respectively. Physicians had different levels of expertise in reading V/Q scintigraphy and CTPA. Interpretation was blinded to the initial interpretation and any clinical information or imaging test result. For each modality, results were reported on a binary fashion. V/Q PET/CT scans were read as positive if there was at least one segmental or two subsegmental mismatched perfusion defects. CTPA scans were interpreted as positive if there was a constant intraluminal filling defect. Interobserver agreement was assessed by calculating kappa (κ) coefficients. Results: Out of the 24 V/Q PET-CT scans, the diagnostic conclusion was concordantly negative in 22 patients and concordantly positive in one patient. The remaining scan was interpreted as positive by one reader and negative by three readers. Out of the 24 CTPA scans, the diagnostic conclusion was concordantly negative in 16 and concordantly positive in one. Out of the seven remaining scans, PE was reported by one reader in four cases, by two readers in two cases, by three readers in one case. Most of discordant results on CTPA were related to clots reported on subsegmental arteries. Mean kappa coefficient was 0.79 for V/Q PET-CT interpretation and 0.39 for CTPA interpretation. Conclusions: Interobserver agreement in the interpretation of V/Q PET-CT for PE diagnosis was substantial (kappa 0.79) in a population with a low prevalence of significant PE. Agreement was lower with CTPA, mainly as a result of discrepancies at the level of the subsegmental arteries., Competing Interests: Unrelated to this study, MH reports grant funding from the Prostate Cancer Foundation,Movember, Prostate Cancer Foundation of Australia, Medical Research Future Fund (MRFF), Victorian Cancer Agency and the U.S. Department of Defence. He has received honorarium for educational lectures or travel from Janssen, Sanofi Genzyme and Ipsen. MH has received industry grant funding from Endocyte (now a Novartis company). The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Le Pennec, Iravani, Woon, Dissaux, Gest, Le Floch, Salaün, Le Gal, Hofman, Hicks and Le Roux.)

Abstract: We report an increased uptake of 18F-choline in the right cerebellopontine angle area in a 73-year-old man with biochemical failure prostate cancer after radical prostatectomy, potentially suggestive of bone metastasis in the base of the skull. A brain MRI was also performed showing an intense gadolinium enhancement focus in the same area, concordant with a right vestibular schwannoma, subsequently histologically proven. This case underlines that schwannoma is a diagnostic pitfall in 18F-choline PET/CT, suggesting this radiolabeled tracer as a promising tool for brain tumors characterization due to its higher signal-to-background ratio than 18F-FDG., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Triplet chemotherapy (FOLFOXIRI) + bevacizumab regimen is indicated as first-line treatment of BRAF-mutated metastatic colorectal cancer (mCRC). Nevertheless, its proven therapeutic efficacy in clinical trials was solely based on partial morphologic responses assessed by CT. To date, only 1 case of complete response assessed by FDG PET/CT was reported in literature in BRAF-mutated mCRC, but treated with doublet chemotherapy (FOLFIRI) + cetuximab regimen. We report a complete metabolic response assessed by FDG PET/CT, maintained over time (13 months) in a 60-year-old woman with BRAF-mutated mCRC treated by FOLFOXIRI-bevacizumab. This also confirms that FDG PET/CT is emerging as a useful approach for therapeutic assessment of targeted drugs in mCRC.

Background: There is currently no reliable or validated tool to delineate and quantify functional lung volumes with ventilation/perfusion (V/Q) SPECT/CT. The main challenges encountered include the physiological non-uniformity of lung function, such as the anterior-to-posterior gradient on perfusion images, and the lack of ground truth to assess the accuracy of delineation algorithms. In that respect, Monte-Carlo simulations would be an interesting tool. Thus, the aim of this study was to develop a realistic model of dual-isotope lung V/Q SPECT-CT Monte-Carlo simulations, integrating the anterior to posterior gradient on perfusion. Methods: Acquisitions and simulations parameters were set in accordance to nuclear medicine guidelines for V/Q lung SPECT-CT. Projections were acquired and simulated, then the reconstructions [with and without attenuation correction (AC)] were compared. A model was built from a patient's CT scan. To model the anterior to posterior gradient, the lungs were divided into sixteen coronal planes, where a rising radioactivity concentration was set. To assess the realism of simulations, they were compared to a normal co-registered normal cases database in terms of pixelwize Z-score map. Results: For ventilation images, mean (SD) Zscores on Zscore maps were -0.2 (0.7) and -0.2 (0.7) for AC and noAC images, respectively. For perfusion images, mean (SD) Zscores were -0.2 (0.6) and -0.1 (0.6) for AC and noAC images, respectively. Conclusion: We developed a model for dual isotopes lung V/Q SPECT-CT, integrating the anterior-to-posterior gradient on perfusion images. This model could be used to build a catalog of clinical scenarios, in order to test delineation methods of functional lung volumes., (Copyright © 2020 Bourhis, Wagner, Essayan, Robin, Le Pennec, Salaun and Le Roux.)

Background: The objective of this study was to assess the therapeutic and prognostic impact of integrating18F-fluorodeoxyglucose (18-FDG) positron emission tomography (PET)/computed tomography (CT) into work-up (WU) at initial staging of patients with head and neck squamous cell carcinoma (HNSCC). Method: 477 consecutive patients (414M/63F, mean age 62.3 ± 9.7 years) with newly diagnosed HNSCC who underwent pre-treatment 18-FDG PET/CT were retrospectively included. The 18-FDG PET/CT stage (sPET) was compared to the conventional work-up stage (sCWU). A group of cancer specialists determined whether integrating PET/CT into WU at initial staging had an impact on the therapeutic decision, classifying the clinical impact as high (change in therapeutic modality), medium (change in the radiotherapy or surgical procedure), or low (modification of TNM staging and/or detection of synchronous cancer without high or medium impact). Three-year overall survival (OS) was considered as primary endpoint of the prognostic analysis. Results: 18-FDG PET/CT had a clinical impact in 221 patients (46.3%) with a medium or high impact on management in 94 (19.5%) patients. Medium and high impact of 18-FDG PET/CT was statistically equivalent between sCWU-stage I/II and III/IV subgroups ( p = 0.02). 42 patients were PET/CT-upstaged from early stage I/II to advanced stage III/IV and had a significantly lower 3-year OS than those with concordant CWU and 18-FDG PET/CT early stage (54.8 vs. 82.6%, p = 0.001). Conclusion: This study demonstrated that implementing 18-FDG PET/CT in the initial WU of HNSCC provides valuable staging information with a better prognostic stratification. Patient management was modified for any disease stage, even for early stage I-II, with consequences on survival., (Copyright © 2020 Leclere, Delcroix, Rousset, Valette, Robin, Guezennec, Le Pennec, Gujral, Abgral, Ollivier, Marianowski, Salaun, Schick and Abgral.)

Aim: Several series have already demonstrated that intratumoral subvolumes with high tracer avidity (hotspots) in 18F-flurodesoxyglucose positron-emission tomography (FDG-PET/CT) are preferential sites of local recurrence (LR) in various solid cancers after radiotherapy (RT), becoming potential targets for dose escalation. However, studies conducted on head and neck squamous cell carcinoma (HNSCC) found only a moderate overlap between pre- and post-treatment subvolumes. A limitation of these studies was that scans were not performed in RT treatment position (TP) and were coregistred using a rigid registration (RR) method. We sought to study (i) the influence of FDG-PET/CT acquisition in TP and (ii) the impact of using an elastic registration (ER) method to improve the localization of hotpots in HNSCC. Methods: Consecutive patients with HNSCC treated by RT between March 2015 and September 2017 who underwent FDG-PET/CT in TP at initial staging (PET A ) and during follow-up (PET R ) were prospectively included. We utilized a control group scanned in non treatment position (NTP) from our previous retrospective study. Scans were registered with both RR and ER methods. Various sub-volumes (A X ; x = 30, 40, 50, 60, 70, 80, and 90%SUVmax) within the initial tumor and in the subsequent LR (R X ; x = 40 and 70%SUVmax) were overlaid on the initial PET/CT for comparison [Dice, Jaccard, overlap fraction = OF, common volume/baseline volume = A X nR X /A X , common volume/recurrent volume = A X nR X /R X ]. Results: Of 199 patients included, 43 (21.6%) had LR (TP = 15; NTP = 28). The overlap between A 30 , A 40 , and A 50 sub-volumes on PET A and the whole metabolic volume of recurrence R 40 and R 70 on PET R showed moderate to good agreements (0.41-0.64) with OF and A X nR X /R X index, regardless of registration method or patient position. Comparison of registration method demonstrated OF and A X nR X /R X indices (x = 30% to 50%SUVmax) were significantly higher with ER vs. RR in NTP ( p < 0.03), but not in TP. For patient position, the OF and A X nR X /R X indices were higher in TP than in NTP when RR was used with a trend toward significance, particularly for x=40%SUVmax (0.50±0.22 vs. 0.31 ± 0.13, p = 0.094). Conclusion: Our study suggested that PET/CT acquired in TP improves results in the localization of FDG hotspots in HNSCC. If TP is not possible, using an ER method is significantly more accurate than RR for overlap estimation., (Copyright © 2020 Truffault, Bourhis, Chaput, Calais, Robin, Le Pennec, Lucia, Leclère, Gujral, Vera, Salaün, Schick and Abgral.)