Does 11C-choline PET-CT contribute to multiparametric MRI for prostate cancer localisation?

The aim of this work was to determine whether 11C-choline positron emission tomography (PET)-computed tomography (CT) makes a positive contribution to multiparametric magnetic resonance imaging (MRI) for localisation of intraprostatic tumour nodules. A total of 73 patients with biopsy-proven intermediate- and high-risk prostate cancer were enrolled in a prospective imaging study consisting of T2-weighted (T2w), dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) MRI and 11C-choline PET-CT before radical prostatectomy. Cancerous regions were delineated on the whole-mount prostatectomy sections and on the different MRI modalities and analysed in 24 segments per patient (3 sections, 8 segments each). To analyse PET-CT images, standardized uptake values (SUV) were calculated per segment. In total, 1,752 segments were analyzed of which 708 (40.4%) were found to be malignant. A high specificity (94.7, 93.6 and 92.2%) but relatively low sensitivity (31.2, 24.9 and 44.1%) for tumour localisation was obtained with T2w, DCE and DW MRI, respectively. Sensitivity values significantly increased when combining all MRI modalities (57.2%). For PET-CT, mean SUVmax of malignant octants was significantly higher than mean SUVmax of benign octants (3.68±1.30 vs. 3.12±1.02, p<0.0001). In terms of accuracy, the benefit of adding PET-CT to (multiparametric) MRI was less than 1%. The additional value of 11C-choline PET-CT to MRI in localising intraprostatic tumour nodules is limited, especially when multiparametric MRI is used.