Table 3.

Comparison of MRI findings for Granulomatous Prostatitis and Prostate Cancer

Sequence	Granulomatous Prostatitis	Prostate Cancer
T2	Diffuse or nodular pattern Low signal intensity lesions Loss of normal peripheral zone/transitional zone architecture May show capsular irregularity, suggestive of high stage prostate cancer	Round or ill-defined, low signal intensity focus in peripheral zone. May appear as lenticular or homogeneous signal mass with indistinct margins (“erased charcoal sign”) in transitional zone. Higher grade cancers often have lower signal intensity than low grade tumours.
DWI	High signal intensity on DWI Very low ADC values compared to normal normal peripheral zone tissue (mean ADC 702 ± 79×10−6 mm/s2).	High signal intensity on DWI Low ADC values compared to normal peripheral zone tissue. ADC values inversely correlate with increasing Gleason score. Lowest values seen in Gleason > 8 cancers.
DCE	Early diffuse enhancement seen in all cases. A subset of patients have rim enhancement, consistent with caseous necrosis and abscess formation.	Prostate cancer may reveal early and increased enhancement Lack of enhancement does not exclude malignancy Best used to discriminate equivocal lesions in the peripeheral zone.