To assess the diagnostic accuracy and inter-observer agreement of T2-weighted (T2W) and diffusion-weighted (DW) magnetic resonance imaging (MRI) for mapping intra-prostatic tumour lesions (IPLs) for the purpose of focal dose-escalation in prostate cancer radiotherapy.
Twenty-six men selected for radical treatment with radiotherapy were recruited prospectively and underwent pre-treatment T2W+DW-MRI and 5 mm spaced transperineal template-guided mapping prostate biopsies (TTMPB). A ‘traffic-light’ system was used to score both data sets. Radiologically suspicious lesions measuring ≥0.5 cm3 were classified as red; suspicious lesions 0.2-0.5 cm3 or larger lesions equivocal for tumour were classified as amber. The histopathology assessment combined pathological grade and tumour length on biopsy (red = ≥4 mm primary Gleason grade 4/5 or ≥6 mm primary Gleason grade 3). Two radiologists assessed the MRI data and inter-observer agreement was measured with Cohens’ Kappa co-efficient.
Twenty-five of 26 men had red image-defined IPLs by both readers, 24 had red pathology-defined lesions. There was a good correlation between lesions ≥0.5 cm3 classified “red” on imaging and “red” histopathology in biopsies (Reader 1: r = 0.61, p < 0.0001, Reader 2: r = 0.44, p = 0.03). Diagnostic accuracy for both readers for red image-defined lesions was sensitivity 85-86%, specificity 93-98%, positive predictive value (PPV) 79-92% and negative predictive value (NPV) 96%. Inter-observer agreement was good (Cohen’s Kappa 0.61).
MRI is accurate for mapping clinically significant prostate cancer; diffusion-restricted lesions ≥0.5 cm3 can be confidently identified for radiation dose boosting.
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 2019 Sep 05 [Epub ahead of print]
E J Alexander, J R Murray, V A Morgan, S L Giles, S F Riches, S Hazell, K Thomas, S A Sohaib, A Thompson, A Gao, D P Dearnaley, N M DeSouza
The Royal Marsden NHS Foundation Trust, Sutton, UK; The Institute of Cancer Research, Sutton, UK. Electronic address: ., The Royal Marsden NHS Foundation Trust, Sutton, UK; The Institute of Cancer Research, Sutton, UK. Electronic address: ., The Institute of Cancer Research, Sutton, UK. Electronic address: ., The Institute of Cancer Research, Sutton, UK. Electronic address: ., The Institute of Cancer Research, Sutton, UK. Electronic address: ., The Royal Marsden NHS Foundation Trust, Sutton, UK. Electronic address: ., The Royal Marsden NHS Foundation Trust, Sutton, UK., The Royal Marsden NHS Foundation Trust, Sutton, UK. Electronic address: ., The Royal Marsden NHS Foundation Trust, Sutton, UK. Electronic address: ., The Royal Marsden NHS Foundation Trust, Sutton, UK; The Institute of Cancer Research, Sutton, UK. Electronic address: ., The Royal Marsden NHS Foundation Trust, Sutton, UK; The Institute of Cancer Research, Sutton, UK. Electronic address: ., The Royal Marsden NHS Foundation Trust, Sutton, UK; The Institute of Cancer Research, Sutton, UK. Electronic address: .