A MiFLOW Project
MISSING PROJECT NAME
Larger prostates are expected to obstruct the flow of urine, yet gland size correlates only weakly with symptoms and says little about men who are symptomatic without an enlarged prostate. We hypothesize that the prostate obstructs either by bulk or by stiffness, and that the mechanical state of the tissue surrounding the urethra is the part of the picture current evaluation leaves out. In this project we propose to measure that stiffness non-surgically, using transrectal shear wave elastography of the prostate.
Evaluation of benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS) rests on symptom questionnaires, uroflowmetry, post-void residual, and anatomic measures of the gland — above all prostate volume. Conceptually, a larger prostate is expected to cause bladder outlet obstruction and the symptoms that follow. In practice, size correlates only weakly with symptoms, and it is uninformative in the men who are symptomatic even though their glands are not enlarged. Size describes only one way for a prostate to obstruct: by bulk.
The histological changes of BPH occur in the transition zone, the tissue immediately surrounding the prostatic urethra. Those changes alter the mechanical properties of that tissue as well as its volume, and stiffer periurethral tissue limits how wide the urethra can open during voiding. Stiffness is therefore a plausible second route to obstruction — but it is not measured in routine care. The existing ways to reach it are invasive: urethral resistance from urodynamic studies (UDS), or mechanical testing of excised tissue.
In this project we propose to measure that stiffness less-invasively, with transrectal shear wave elastography (SWE) of the transition zone. SWE derives tissue stiffness from the speed of shear waves induced acoustically in the tissue, and is already established in breast, liver, and thyroid imaging. Using an endocavitary probe, we sample the tissue immediately around the prostatic urethra, along with the peripheral zone as a reference within the same gland. Our aim is to establish whether size and stiffness are complementary biomarkers describing two routes to obstruction — large, soft glands that obstruct by bulk, and small, stiff ones that do not — and, in the longer run, to identify the men who obstruct without an enlarged prostate, who stand to benefit least from treatments directed at reducing gland volume.
