Published in:
Open Access
01-08-2015 | Review
False positive and false negative diagnoses of prostate cancer at multi-parametric prostate MRI in active surveillance
Authors:
Jeffrey S. Quon, Bardia Moosavi, Maneesh Khanna, Trevor A. Flood, Christopher S. Lim, Nicola Schieda
Published in:
Insights into Imaging
|
Issue 4/2015
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Abstract
MP-MRI is a critical component in active surveillance (AS) of prostate cancer (PCa) because of a high negative predictive value for clinically significant tumours. This review illustrates pitfalls of MP-MRI and how to recognise and avoid them. The anterior fibromuscular stroma and central zone are low signal on T2W-MRI/apparent diffusion coefficient (ADC), resembling PCa. Location, progressive enhancement and low signal on b ≥1000 mm²/s echo-planar images (EPI) are differentiating features. BPH can mimic PCa. Glandular BPH shows increased T2W/ADC signal, cystic change and progressive enhancement; however, stromal BPH resembles transition zone (TZ) PCa. A rounded morphology, low T2 signal capsule and posterior/superior location favour stromal BPH. Acute/chronic prostatitis mimics PCa at MP-MRI, with differentiation mainly on clinical grounds. Visual analysis of diffusion-weighted MRI must include EPI and appropriate windowing of ADC. Quantitative ADC analysis is limited by lack of standardization; the ADC ratio and ADC histogram analysis are alternatives to mean values. DCE lacks standardisation and has limited utility in the TZ, where T2W/DWI are favoured. Targeted TRUS-guided biopsies of MR-detected lesions are challenging. Lesions detected on MP-MRI may not be perfectly targeted with TRUS and this must be considered when faced with a suspicious lesion on MP-MRI and a negative targeted TRUS biopsy histopathological result.
Keypoints
• Multi-parametric MRI plays a critical role in prostate cancer active surveillance.
• Low T2W signal intensity structures appear dark on ADC, potentially simulating cancer.
• Stromal BPH mimics cancer at DWI and DCE.
• Long b value trace EPI should be reviewed
• Targeted biopsy of MR-detected lesions using TRUS guidance may be challenging.