Table 3.

Magnetic resonance imaging (MRI) v digital rectal examination in 245 patients assessed by both methods undergoing primary surgery or short course radiotherapy followed by immediate surgery

	Clear	Involved	Grand total
MRI prediction at circumferential resection margin:
Clear	215	15	230
Involved	4	11	15
Grand total*	219	26	245
Digital rectal examination:
Mobile	161	16	177
Fixed/tethered	58	10	68
Grand total†	219	26	245

^*Accuracy=226/245 (92%); sensitivity=11/26 (42%), positive predictive value (PPV)=11/15 (73%); specificity=215/219 (98%); negative predictive value (NPV)=215/230 (93%).

^†Accuracy=171/245 (70%); sensitivity=10/26 (38%); specificity=161/219 (74%); PPV=10/68 (15%); NPV=161/177 (91%).