Purpose: To assess (1) the potential benefit that MRI may bring to prostate radiotherapy planning and delivery; (2) a method of improving registration of MRI and CT imaging to aid the RT planning workflow; (3) the role of in-bore MRI guided biopsy in informing management; (4) dosimetric outcome and toxicity of an integrated High Dose Rate (HDR-B) or Volumetric Modulated Arc Therapy (VMAT-IB) boost to the area of dominant disease within the prostate; (5) whether a predictive response can be identified measuring changes in Diffusion Weighted Imaging (DWI) and Dynamic Contrast Enhancement (DCE) during prostate RT after neo-adjuvant HT (NA-HT); (6) the necessity of hormone therapy (HT) with dose escalated radiotherapy (DE-RT) for intermediate risk prostate cancer. Methods: (1) Perform a systematic review of literature pertaining to MRI and image guided radiotherapy; (2) compare registration accuracy, based on displacement of fiducial markers or degree of overlap of segmented prostate measured by Dice Similarity Coefficient (DSC), of MRI and CT for 14 patients after conventional operator driven visual matching and then an additional registration step using interstitial points identified on high quality volumetric CT (HQVCT); (3) assess the predictive power of in-bore MRI guided biopsy of areas with suspicious appearance on multi-parametric MRI by comparing biopsy accuracy to histological findings and repeat biopsy results for 42 PIRADS 4-5 lesions in 31 men; (4) analyse patients treated in a prospective study receiving standard radiotherapy to the prostate plus a HDR-B (20 patients) or VMAT-IB (26) to a total dose of 250 Gy BED to assess acute and late toxicity and dosimetric variation between the two methods; (5) prospectively recruit 15 patient who have received NA-HT and perform DWI and DCE before, during and after completion of radiotherapy to look for significant changes in values in normal and malignant tissue which may predict for ultimate outcome; (6) Assess clinical outcome for patients receiving 75.6 – 78 Gy +/- bicalutamide. Results: (1) The review has quantified uncertainties in treatment delivery and the degree that the addition of MRI may mitigate this; (2) point based registration of CT and MRI imaging after visual registration achieved a significant reduction in fiducial marker displacement and a significant increase in DSC; (3) seven lesions targeted by in-bore MR guided biopsy had non-significant or negative results, most with biopsy needle deflected to the target periphery with four confirmed false negative on repeat biopsy; (4) with a median follow up of 12 months acute and late toxicity was similar after either treatment with HDR-B delivering a significantly higher dose to a proportion of the gross tumour volume (GTV) but with significantly lower minimum dose to the planned target volume (PTV); (5) tumour DWI values during RT after NA-HT were not found to significantly alter, DCE was found to vary significantly during treatment and initial changes correlated with changes in DWI; (6) the addition of bicalutamide did not significantly improve biochemical control or overall survival. Conclusions: (1) Routine use of MRI will to improve radiotherapy planning and delivery; (2) repeat point based registration using interstitial points has the potential to improve visual CT and MRI registration; (3) an in-bore MRI guided biopsy has little value in informing a decision to offer focal therapy to an MRI identified PIRADS 4-5 lesion due to its high false negative rate; (4) with limited follow up HDR-B and VMAT-IB appear safe methods of focal dose escalation although with significant dosimetric variations;(5) early changes in DWI and DCE during RT after NA-HT appear to correlate, longer follow up will assess their prognostic value; (6) A benefit of HT combined with DE-RT was not shown in this study.

OBJETIVO: Avaliar a relação entre mensurações de gordura (subcutânea e periprostática) realizadas em ressonância magnética, com o prognóstico do paciente portador de câncer de próstata. MATERIAIS E MÉTODOS: A mensuração da gordura periprostática e subcutânea com exame de ressonância magnética com ênfase na próstata foram realizadas em 58 pacientes com o diagnóstico histopatológico de câncer de próstata. Dados demográficos, clínicos e patológicos dos pacientes foram coletados e a correlação com o prognóstico, realizada. RESULTADOS: Na análise univariada, as gorduras periprostática e a subcutânea indicaram serem preditores de evolução desfavorável com significância estatística para o observador 1, no caso da gordura periprostática e para o observador 2 no caso da gordura subcutânea. Na análise multivariada, não houve associação com significância estatística. CONCLUSÃO: A associação entre obesidade e o câncer de próstata é complexa. Os dados obtidos neste estudo indicam que a medida da gordura periprostática, pelas imagens em T2, na RM, podem ser um preditor independente, da evolução desfavorável de pacientes com neoplasia de próstata / PURPOSE: Evaluate the relationship between fat measurements (subcutaneous and periprostatic) performed on MRI, with the prognosis of the patient with prostate cancer. MATERIALS AND METHODS: Measurements of periprostatic and subcutaneous fat with magnetic resonance imaging with emphasis on the prostate were performed in 58 patients with the histopathological diagnosis of prostate cancer. Demographic, clinical and pathological data of the patients were collected and the correlation with the prognosis was performed. RESULTS: In the univariate analysis, the periprostatic and subcutaneous fat were predictors of unfavorable evolution with statistical significance for the observer 1, in the case of the periprostatic fat and for the observer 2 in the case of the subcutaneous fat. In the multivariate analysis, there was no association with statistical significance. CONCLUSION: The association between obesity and prostate cancer is complex. The data obtained in this study indicate that the measurement of periprostatic fat by T2-weighted images in MRI may be an independent predictor of the unfavorable evolution of patients with prostate neoplasia