Endo-rectal coil magnetic resonance imaging in clinically localized prostate cancer: is it accurate?

We assessed the staging accuracy of endo-rectal coil magnetic resonance imaging (MRI) in patients with clinically localized prostate cancer.

In a prospective study 56 consecutive patients underwent endo-rectal coil MRI before scheduled surgery. The ability of MRI to identify tumor involvement of the periprostatic soft tissue, seminal vesicles and pelvic lymph nodes was assessed by comparison with final pathological stage.

Specificity of MRI was relatively high (84% for periprostatic soft tissue, 93% for seminal vesicles and 91% for pelvic lymph nodes) and sensitivity was low (22, 23 and 0%, respectively). Accuracy was 64% for identification of periprostatic soft tissue invasion, 77% for seminal vesicle invasion and 86% for pelvic lymph node metastases. Had we excluded from surgery patients with MRI evidence of extraprostatic disease our organ confined disease rate would have improved by 16.6%. However, this improvement would have been obtained at the expense of incorrectly excluding from surgery 21% of our patients with pathologically organ confined disease because of false-positive MRI predictions.

Endo-rectal coil MRI is not sufficiently accurate to influence the treatment of patients with clinically localized prostate cancer. Therefore, we advise against routine use of this imaging modality in staging such cases.