Heating of the scrotum by high-field-strength MR imaging

Sterility can occur in mammals if spermatogenic tissue is acutely or chronically heated to levels equal to or greater than body temperature. High-field-strength MR imaging has been shown to elevate tissue temperatures, particularly if high levels of RF radiation are used. To determine if MR imaging above the recommended level for RF radiation is associated with heating of the scrotum, scrotal skin temperatures were measured in eight subjects immediately before and after MR imaging of the scrotum with a 1.5-T, 64-MHz MR scanner at mean whole-body average specific absorption rates ranging from 0.56 to 0.84 W/kg (mean, 0.72 W/kg). The average imaging time was 23 min. A statistically significant (p less than .01) increase in average scrotal skin temperature was associated with MR imaging (before MR imaging, 30.8 degrees C; after MR imaging, 32.3 degrees C). The largest change in temperature was 3.0 degrees C, and the highest temperature measured was 34.1 degrees C. MR imaging at relatively high specific absorption rates produced a statistically significant increase in average scrotal skin temperature. However, the recorded temperatures were below the threshold known to affect spermatogenesis in mammals.