, Volume 23, Issue 4, pp 1158-1166,
Open Access This content is freely available online to anyone, anywhere at any time.
Date: 01 Nov 2012

Routine pelvic MRI using phased-array coil for detection of extraprostatic tumour extension: accuracy and clinical significance

Abstract

Objectives

To determine the accuracy and assess the clinical significance of surface-coil 1.5-T magnetic resonance imaging (MRI) for the detection of locally advanced prostate cancer (PCa).

Methods

Between December 2007 and January 2010, we examined 209 PCa patients (mean age = 62.5 years) who were consecutively treated with robot-assisted laparoscopic prostatectomy and prospectively staged by MRI. One hundred and thirty-five patients (64.6 %) had locally advanced disease. Conventional clinical tumour stage and MRI-assessed tumour stage were compared with histopathological tumour stage (pT). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy (OA) were calculated using pT as the “gold standard”. Overstaged and understaged cases at MRI were reviewed.

Results

Sensitivity, specificity, PPV, NPV and OA for the detection of locally advanced disease were 25.9, 95.9, 92.1, 41.2 and 50.5 % and 56.3, 82.2, 85.4, 50.4 and 65.4 % for clinical staging and MRI, respectively. Among patients understaged at MRI, the resection margins were free in 64.4 % of the cases (38/59).

Conclusions

Although the accuracy was limited, the detection of locally advanced disease improved substantially when MRI was added to routine clinical staging. The majority of the understaged patients nevertheless achieved free margins. When assessing the clinical significance of MRI staging the extent of extraprostatic extension has to be considered.

Key Points

MRI substantially improves detection of locally advanced prostate cancer

MRI has limited overall staging accuracy

Most T3 cancers unrecognised at MRI still achieved free resection margins

Assessing the true clinical contribution of MRI remains challenging