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Purpose The performance of 68  Ga-PSMA PET/CT-MR has been evaluated in prostate cancer (PCa), showing significant results. However, even a technically accurate imaging procedure requires a high interobserver agreement in its interpretation to implement in patients’ management. This study aims to perform a systematic review and meta-analysis on the interobserver variability in 68  Ga-PSMA PET/CT-MR imaging in PCa patients. Methods We conducted a systematic review and meta-analysis on the interobserver variability, including studies: (1) providing Kappa (K) as the inter-observer agreement test or the essential data to calculate it, (2) providing the K confidence interval or the essential crude data to calculate it, (3) measuring K statistic based on the appropriate use criteria for the inter-observer agreement. Results Twelve studies, providing 1585 68  Ga-PSMA PET/CT-MR studies reviewed by 62 independent readers, were included. In general, the pooled inter-observer agreement was interpreted as substantial for all analyzed groups, including tumoral lesions in the prostate bed, lymphadenopathies, bone metastasis, and soft-tissue metastasis (all between 0.6 and 0.8). The regional lymphadenopathy group (0.74) obtained the highest agreement, while the lowest was for soft tissue metastasis (0.65). Conclusion This study showed a substantial interobserver agreement in the overall interpretation and detecting locoregional and distant involvement with 68  Ga-PSMA PET/CT-MR in PCa patients.

BackgroundArtificial intelligence (AI) algorithms based on deep convolutional networks have demonstrated remarkable success for image transformation tasks. State-of-the-art results have been achieved by generative adversarial networks (GANs) and training approaches which do not require paired data. Recently, these techniques have been applied in the medical field for cross-domain image translation.PurposeThis study investigated deep learning transformation in medical imaging. It was motivated to identify generalizable methods which would satisfy the simultaneous requirements of quality and anatomical accuracy across the entire human body. Specifically, whole-body MR patient data acquired on a PET/MR system were used to generate synthetic CT image volumes. The capacity of these synthetic CT data for use in PET attenuation correction (AC) was evaluated and compared to current MR-based attenuation correction (MR-AC) methods, which typically use multiphase Dixon sequences to segment various tissue types.Materials and methodsThis work aimed to investigate the technical performance of a GAN system for general MR-to-CT volumetric transformation and to evaluate the performance of the generated images for PET AC. A dataset comprising matched, same-day PET/MR and PET/CT patient scans was used for validation.ResultsA combination of training techniques was used to produce synthetic images which were of high-quality and anatomically accurate. Higher correlation was found between the values of mu maps calculated directly from CT data and those derived from the synthetic CT images than those from the default segmented Dixon approach. Over the entire body, the total amounts of reconstructed PET activities were similar between the two MR-AC methods, but the synthetic CT method yielded higher accuracy for quantifying the tracer uptake in specific regions.ConclusionThe findings reported here demonstrate the feasibility of this technique and its potential to improve certain aspects of attenuation correction for PET/MR systems. Moreover, this work may have larger implications for establishing generalized methods for inter-modality, whole-body transformation in medical imaging. Unsupervised deep learning techniques can produce high-quality synthetic images, but additional constraints may be needed to maintain medical integrity in the generated data.

IntroductionThe aim of this study was to evaluate the association between average perinephric fat (APF) and surgical complications and survival in individuals with endometrial cancer (EC).MethodsThis is a retrospective cohort study of individuals with EC who underwent surgical staging in a tertiary cancer centre in Canada (2015 – 2021). AFP was measured on pre-operative CT scans. Baseline characteristics, surgical complications and survival data were compared between patients with APF < 2.2 cm and those with AFP ≥ 2.2 cm. Cox proportional hazard model was used to evaluate the association between APF and overall survival (OS) and progression-free survival (PFS).ResultsOverall, 297 patients were included. Of whom, n=271 had APF <2.2 cm and n=26 had APF ≥ 2.2 cm. Baseline characteristics are presented in table 1. Patients with APF ≥ 2.2 cm had higher rates of failed sentinel lymph node mapping (31% vs 6%, p<0.001). There were no differences between groups in intraoperative (3% vs 4%, p=0.61) and postoperative complications (14% vs 19%, p=0.71). On univariable analysis, APF was not associated with OS (HR 1.58, 95% CI 0.90–2.78, p=0.11). However, increase in APF was significantly associated with worse PFS (HR 1.49, 95% CI 1.08 -2.06, p=0.02). In a multivariable analysis including age, stage, LVSI and deep myometrial invasion, the association between APF and PFS was not statistically significant (HR 1.35, 95% CI 0.96–1.91, p=0.08). Conclusion/ImplicationsIn this cohort of individuals with EC, there was a trend towards worse PFS with increased APF. However, increased APF did not impact perioperative complications or OS.Abstract EP164/#666 Table 1Baseline characteristics

This study examined whether radiomic features extracted from PET and MRI can enhance prognostication and staging in anal squamous cell carcinoma. A PET-derived shape feature, SHAPE_Volume(vx)(log), was a strong predictor of progression-free survival, and a two-feature model incorporating a heterogeneity measure (GLZLM_SZE) further improved long-term predictive performance. Additionally, eleven PET- and MRI-derived features reliably distinguished early (stage I/II) from advanced (stage III/IV) disease. These findings support the potential of integrated PET/MRI radiomics as non-invasive biomarkers for refined staging and individualized risk stratification, offering clinically meaningful information that may assist treatment planning and patient management.

Objective The aim of this study was to systematically review the literature to evaluate the clinical performance of integrated 18 F-FDG PET/MR as compared with 18 F-FDG PET/CT in oncologic imaging. Methods The literature was searched using MEDLINE and EMBASE via OVID. Studies comparing the diagnostic accuracy of integrated 18 F-FDG PET/MR and 18 F-FDG PET/CT in the diagnosis, staging/restaging, assessment of treatment response, or evaluation of metastasis in patients with suspected or diagnosed cancers were deemed eligible for inclusion. Risk of bias and applicability concerns were assessed using the QUADAS-2 tool. Results Twenty studies met the inclusion criteria. The overall quality of the studies was rated favorably with bias or applicability concerns in a few studies. Our review suggests that 18 F-FDG PET/MR performs comparably to 18 F-FDG PET/CT in the detection of local lymph node and distant metastases and superiorly in determining the local extent of tumor. SUV obtained from 18 F-FDG PET/MR correlated highly with those obtained from 18 F-FDG PET/CT. Conclusions Based on early evidence, 18 F-FDG PET/MR is comparable to 18 F-FDG PET/CT in the clinical scenarios examined in this review. The potential for interchangeability of 18 F-FDG PET/MR with 18 F-FDG PET/CT will vary by indication and the body site that is being imaged, with PET scanners integrated with MRI predicted to provide greater detail in the evaluation of local tumor extent, where 18 F-FDG PET/CT can be limited.

Purpose: The aim of the study is to evaluate the prognostic value of a joint evaluation of PET and CT radiomics combined with standard clinical parameters in patients with HL. Methods: Overall, 88 patients (42 female and 46 male) with a median age of 43.3 (range 21–85 years) were included. Textural analysis of the PET/CT images was performed using freely available software (LIFE X). 65 radiomic features (RF) were evaluated. Univariate and multivariate models were used to determine the value of clinical characteristics and FDG PET/CT radiomics in outcome prediction. In addition, a binary logistic regression model was used to determine potential predictors for radiotherapy treatment and odds ratios (OR), with 95% confidence intervals (CI) reported. Features relevant to survival outcomes were assessed using Cox proportional hazards to calculate hazard ratios with 95% CI. Results: albumin (p = 0.034) + ALP (p = 0.028) + CT radiomic feature GLRLM GLNU mean (p = 0.012) (Area under the curve (AUC): 95% CI (86.9; 100.0)—Brier score: 3.9, 95% CI (0.1; 7.8) remained significant independent predictors for PFS outcome. PET-SHAPE Sphericity (p = 0.033); CT grey-level zone length matrix with high gray-level zone emphasis (GLZLM SZHGE mean (p = 0.028)); PARAMS XSpatial Resampling (p = 0.0091) as well as hemoglobin results (p = 0.016) remained as independent factors in the final model for a binary outcome as predictors of the need for radiotherapy (AUC = 0.79). Conclusion: We evaluated the value of baseline clinical parameters as well as combined PET and CT radiomics in HL patients for survival and the prediction of the need for radiotherapy treatment. We found that different combinations of all three factors/features were independently predictive of the here evaluated endpoints.

Correspondence to Dr Geneviève Bouchard-Fortier, Gynecologic Oncology, Princess Margaret Hospital Cancer Centre, Toronto, ON M5G 2C1, Canada; genevieve.bouchard-fortier@uhn.ca Case presentation A 35-year-old woman G5P2 was referred to the gynecologic oncology service for evaluation and management of a large cornual mass on MRI. Given the persistent low level serum HCG and MRI findings, our differential diagnosis included a placenta increta, intermediate trophoblastic diseases such as placental site trophoblastic tumor or epithelioid trophoblastic tumor, or an arteriovenous malformation. Unfortunately, these same appearances can be appreciated in the presence of gestational trophoblastic disease, with the distinguishing difference being the presence or absence of an intermediate T2 signal intensity mass on MRI and human chorionic gonadotropin. 1 Arteriovenous malformations may also have a ‘cluster of grapes’ appearance given the presence of extensive cystic spaces without a true solid component. [...]with regard to the role of ancillary studies in these cases, the diagnosis of placenta accreta/increta/percreta is one which is made primarily on morphologic findings. 3 The gross features are of paramount importance, and close inspection for serosal breach, evidence of prior cesarian section scar and abnormal placental location (such as placenta previa) as well as thorough dissection to evaluate the depth of placental penetration into myometrium are warranted. 4 Judicious sampling for histology should reveal the cardinal feature of all these disorders—namely, implantation of placenta into myometrium without intervening decidua—which is usually evident on routine H&E [hematoxylin and eosin] staining.

Detection of skeletal metastases in patients with prostate cancer or breast cancer remains a major clinical challenge. We aimed to compare the diagnostic performance of 99mTc-methylene diphosphonate (99mTc-MDP) single-photon emission CT (SPECT) and 18F-sodium fluoride (18F-NaF) PET–CT for the detection of osseous metastases in patients with high-risk prostate or breast cancer. MITNEC-A1 was a prospective, multicentre, single-cohort, phase 3 trial conducted in ten hospitals across Canada. Patients aged 18 years or older with breast or prostate cancer with a WHO performance status of 0–2 and with high risk or clinical suspicion for bone metastasis, but without previously documented bone involvement, were eligible. 18F-NaF PET–CT and 99mTc-MDP SPECT were done within 14 days of each other for each participant. Two independent reviewers interpreted each modality without knowledge of other imaging findings. The primary endpoint was the overall accuracy of 99mTc-MDP SPECT and 18F-NaF PET–CT scans for the detection of bone metastases in the per-protocol population. A combination of histopathological, clinical, and imaging follow-up for up to 24 months was used as the reference standard to assess the imaging results. Safety was assessed in all enrolled participants. This study is registered with ClinicalTrials.gov, NCT01930812, and is complete. Between July 11, 2014, and March 3, 2017, 290 patients were screened, 288 of whom were enrolled (64 participants with breast cancer and 224 with prostate cancer). 261 participants underwent both 18F-NaF PET–CT and 99mTc-MDP SPECT and completed the required follow-up for statistical analysis. Median follow-up was 735 days (IQR 727–750). Based on the reference methods used, 109 (42%) of 261 patients had bone metastases. In the patient-based analysis, 18F-NaF PET–CT was more accurate than 99mTc-MDP SPECT (84·3% [95% CI 79·9–88·7] vs 77·4% [72·3–82·5], difference 6·9% [95% CI 1·3–12·5]; p=0·016). No adverse events were reported for the 288 patients recruited. 18F-NaF has the potential to displace 99mTc-MDP as the bone imaging radiopharmaceutical of choice in patients with high-risk prostate or breast cancer. Canadian Institutes of Health Research.

In this Research Ethics Board-approved retrospective study, we evaluated pre-infusion [ 18 F]FDG PET/CT prognostic value in relapsed/refractory diffuse large B-cell lymphoma (DLBCL) patients undergoing chimeric antigen T-cell (CAR-T) therapy. A total of 159 Patients treated with CAR-T between 2018 and 2023 were reviewed. Deauville scores 4 and 5 were considered to be a significant residual disease at baseline. Standardized uptake values (SUVs), whole-body metabolic tumour volume (MTV) and total lesion glycolysis (TLG) were calculated. Additionally, the furthest distance between tumoral lesions throughout the body (Dmax) and from the spleen (spleen Dmax) were measured. Survival analyses evaluated the predictive value of the clinical and imaging-derived variables for progression-free survival (PFS) and overall survival (OS) prognostication. Of 129 DLBCL patients with pre-infusion [ 18 F]FDG PET/CT, 117/129 (91%) had significant residual disease. The median PFS and OS post-CAR-T were six and nine months, respectively. For PFS, variables that remained significant in the multivariate analysis were serum LDH (HR = 1.68) and TLG (HR = 4.31), being independent predictors of PFS. Considering OS, the only variable which retained its significance in the multivariate analysis was [ 18 F]FDG PET/CT-derived standardized Dmax (HR = 3.28). Pre-infusion [ 18 F]FDG PET/CT can provide valuable prognostic information in CAR-T candidates, enhancing patient management.