A noninvasive technique for monitoring changes in canine prostatic size in vivo

We describe a procedure for monitoring changes in canine prostatic size. Metal beads were sutured to the surface of the prostate and the interbead distances were derived from two X-rays taken at right angles. Prostatic hyperplasia was induced by castration and injection of 5 alpha-androstane-3 alpha, 17 beta-diol and 17 beta-estradiol. Prostatic regression was caused by castration without further treatment. Although growth of the prostate was nonuniform, changes in prostatic volume were shown to be related to the third power of the distance between appropriate beads. This monitoring technique can be repeated every 2nd day if necessary, and thus has an advantage over procedures that require repeated laparotomies. Significant increases in prostatic volume could be detected within 5 days after steroid injection.