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Aim To assess the diagnostic accuracy of whole-body magnetic resonance imaging (WB-MRI) for metastatic disease in patients with solid small round cell tumours (SRCT) by comparing it with routine staging procedures (standard of care). Materials and methods Eligible cases of neuroblastoma, primitive neuroectodermal tumour, and rhabdomyosarcoma were enrolled in the study after obtaining informed consent. WB-MRI was undertaken using overlapping coronal T1 and short-tau inversion recovery (STIR) sequences. Lesions were classified into skeletal, pulmonary, and soft-tissue types. Conventional staging, which consisted of combined positron-emission tomography & computed tomography (PET-CT), bone scintigraphy & bone marrow biopsy for bone metastases, CT thorax for lung metastases, combined PET-CT, metaiodobenzylguanidine (MIBG) scintigraphy (in neuroblastoma) for soft tissue metastases and clinical evaluation was used as the reference standard. Parameters for diagnostic accuracy were calculated. Results Thirty-four out of forty patients enrolled were included in final analysis, half of them having metastatic disease. The sensitivity, specificity, positive and negative predictive value, and the diagnostic accuracy of WB-MRI and PET-CT for skeletal metastases as compared to reference standard were 91.9%, 99.8%, 97.4%, 99.6%, and 95.5% and 99.1%, 99.9%, 99.1%, 99.9%, and 99.9%, respectively. The sensitivity of MRI, only PET and PET-CT with plain CT thorax was 30%, 40%, and 100%, respectively, for lung metastases. The sensitivity of MRI for soft-tissue lesions was 76.9%. Conclusion WB-MRI is a radiation-free tool with high diagnostic accuracy for the evaluation of metastatic disease to the marrow. The rate of detection of soft-tissue metastases, such as nodal metastases, is less when WB-MRI is compared with conventional staging using coronal STIR images. CT thorax is essential for accurate evaluation of lung metastases. [ABSTRACT FROM AUTHOR]

There is a lack of consensus regarding the management of post-chemotherapy residual mass in classical seminoma. The use of fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) may aid the detection of residual masses harbouring viable disease and help to tailor therapy. The aim of this study was to evaluate if PET-CT could identify patients who will benefit from locoregional radiotherapy. This ethics-approved study included patients with advanced classical seminoma primarily treated with standard platinum-based first-line chemotherapy. Patients were either observed or given adjuvant radiotherapy based on the clinician's preference and followed up. For this study, patients were stratified into two groups based on FDG PET-CT residual nodal maximum standardised uptake value (SUVmax): low risk (SUVmax <3) and high risk (SUVmax ≥3). Further subgroup analysis was carried out for patients with residual nodal size ≥3 cm and SUVmax ≥3, and this was considered as the very high risk group. The diagnostic accuracy of FDG PET-CT was assessed and survival was compared between the different groups. Sixty-nine patients were included in the study: 48 patients were observed and 21 received radiotherapy. The low and high risk groups contained 50.7% and 49.3% of the patients, respectively. The very high risk subgroup had 24 patients. At a median follow-up of 44 months, locoregional failures in the radiotherapy and observation cohorts were 0% and 30% (P = 0.059) in the very high risk subgroup and 5.8% and 29.4% (P = 0.078) in the high risk group. The positive predictive value for the very high risk and high risk groups was 30% and 17.1%, respectively. The benefit of locoregional control failed to translate into overall survival benefit. A tailored, FDG PET-based risk-adapted treatment approach can refine the management of post-chemotherapy residual masses in seminoma. In this study, with the largest cohort of advanced seminoma patients treated with radiotherapy reported to date, radiotherapy seems to benefit patients with post-chemotherapy residual mass SUVmax ≥3. • FDG PET-CT can help to optimise the management of post-chemotherapy residual mass in advanced seminoma. • Risk grouping can be carried out based on uptake in residual mass in PET-CT scan. • Residual mass with SUVmax ≥3 seems to benefit from locoregional radiotherapy. [ABSTRACT FROM AUTHOR]

To evaluate the utility of Ga68-PSMA PETCT based response to neoadjuvant androgen deprivation therapy (ADT) as a predictive biomarker in patients with node positive prostate cancer treated with definitive radiotherapy Patients with newly diagnosed non-metastatic adenocarcinoma prostate with regional nodal involvement on index Ga68-PSMA PETCT scan were identified from prospectively maintained institutional database. All patients were started on neoadjuvant ADT and treated with definitive image-guided conformal radiotherapy with long term ADT. Eligible patients also had a response assessment Ga68-PSMA PETCT scan prior to radiotherapy. Patients who had a single PSMA PETCT scan, or who received prior or concurrent abiraterone ordocetaxel were excluded. Imaging parameters including maximum standardized uptake values (SUV max), PSMA tumor volume (PSMA-TV), and total lesion PSMA (TL-PSMA) were calculated separately for prostate and pelvic nodes in the paired Ga68-PSMA PETCT scans done pre-ADT and pre-radiotherapy. Absolute and relative response for these parameters was calculated. Biochemical failure (BCF) was defined by the Phoenix criteria and its association with absolute and relative response in Ga68-PSMA PETCT parameters was tested using the logistic regression analysis. Total 93 patients were eligible for analysis. Median duration of neoadjuvant ADT was 6 months. Response observed in the paired Ga68-PSMA PETCT scans is detailed in Table 1. Complete metabolic response was observed in 62% patients for pelvic nodes and 7% for prostate. Partial metabolic response was observed in 23% for pelvic nodes and 55% for prostate, while stable disease was seen in 11% and 18% for pelvic nodes and prostate respectively. Progressive disease was observed in 4% for pelvic nodes and 14% for prostate. At a median follow up of 37 months, 15 patients (16%) experienced BCF. Median absolute and relative decline in SUV max for pelvic nodes was 8.29 (IQR:3.5-20.3) and 100% (IQR:61.3-100) respectively. Both the absolute and the relative decline in SUV max for pelvic nodes showed statistically significant association with BCF post treatment using logistic regression (p=0.05 each). No significant association was observed for other volumetric parameters. A steeper decline in absolute and relative nodal SUV max on Ga68-PSMA PETCT with neoadjuvant ADT is associated with lower probability of BCF post radiotherapy in node positive prostate cancer. [ABSTRACT FROM AUTHOR]