To establish interobserver reproducibility of tumour volumetry on individual multiparametric(mp) prostate MRI sequences, validate measurements with histology and determine whether functional to morphological volume ratios reflect Gleason score.
Forty-one men with prostate cancer treated with prostatectomy (cohort 1) or radical radiotherapy (cohort 2) who had pre-treatment mp (T2-W, DW-, DCE-) MRI were studied retrospectively. Dominant intraprostatic lesions (DIPLs) were manually delineated on each sequence and volumes compared between observers (n=40 analysable) and with radical prostatectomy (n=20). Volume ratios of DW- and DCE- to T2-W MRI were documented and compared between Gleason grade 3+3, 3+4 and 4+3 or greater categories.
Limits of Agreement of DIPL volumes between observers were: T2-W 0.9, -1.1 cm(3), DW-MRI 1.3, -1.7 cm(3), DCE-MRI 0.74, -0.89 cm(3). In cohort 1, T2-W volumes overestimated fixed specimen histological volumes, (+33% observer 1, +16% observer 2); DW- and DCE-MRI underestimated histological volume, the latter markedly so (-32% observer 1, -79% observer 2). Differences between T2-W, DW- and DCE-MRI volumes were significant (p<10(-8)). The proportional volume of DW- (73.9+18.1 % observer 1, 72.5+21.9% observer 2) and DCE-MRI volume (42.6+24.6% observer 1, 34.3+24.9% observer 2) to T2-W volume was significantly different (p<10(-8)) but these volume ratios did not differ between Gleason grade.
The T2-W MRI DIPL volume variability between observers and with histology best reflects the GTV for radiotherapy planning. The volume of cellular tumour represented by DW-MRI is greater than the vascular (DCE) abnormality; ratios of both to T2-W volume are independent of Gleason score. Advances in knowledge: 1. Manual volume measurement of tumour is reproducible within 1cm(3) between observers on all sequences, confirming suitability across observers for radiotherapy planning. 2. Volumes derived on T2-W MRI most accurately represent in vivo lesion volumes. 3. The proportion of cellular (DW-) or vascular (DCE-) volume to morphological (T2-W) volume is not affected by Gleason score.
The British journal of radiology. 2017 Jan 05 [Epub ahead of print]
Hugh Harvey, Matthew R Orton, Veronica A Morgan, Chris Parker, David Dearnaley, Cyril Fisher, Nandita M deSouza
1 Cancer Research UK Imaging Centre at The Institute of Cancer Research, London and Royal Marsden NHS Foundation Trust, UK., 2 Academic Urology Unit at The Institute of Cancer Research, London and Royal Marsden NHS Foundation Trust, UK., 3 Department of Histopathology at The Institute of Cancer Research, London and Royal Marsden NHS Foundation Trust, UK.