ABSTRACT Diminished bladder contractility is a critical but poorly addressed factor in men with benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS). We propose to test the hypothesis that MRI can be used to identify and quantify specific changes in bladder anatomy and voiding function in men with BPH/LUTS. BPH surgery involves removal of enlarged peri-urethral prostate tissue to reduce resistance to urine flow during the voiding effort. However, diminished bladder contractility is present in many patients with BPH/LUTS and greatly influences the degree of improvement of flow and emptying postoperatively, independent of bladder outlet obstruction. In our recently published studies, we used MRI based imaging to quantify metrics of bladder and prostate anatomy, regional differences in bladder wall thickness, and blood flow. Further, we showed that real-time imaging during voiding combined with computational modeling can quantify metrics of bladder contraction such as the rate of detrusor muscle shortening and urinary flow dynamics parameters such as velocity, pressure, and vorticity. We will use these to compare bladder voiding function in healthy young men and men with BPH/LUTS. We will identify changes in bladder anatomy and the specific mechanisms that impair voiding function and delineate the relative contribution of each mechanism to reduced urine flow and impaired bladder emptying. This MR image-based strategy employs techniques that have been used extensively to assess cardiovascular function. The novelty of the proposal is the adaptation of these techniques to study the bladder. To our knowledge, nothing like it has ever been done. The scientific impact is the implementation and validation of MRI to achieve comprehensive assessment of lower urinary tract anatomy and function in healthy young men and men with BPH/LUTS. Metrics of bladder anatomy and function obtained by MRI will be validated throughout the proposal with measurement of bladder wall thickness determined by ultrasound and the canonical metrics of pressure, flow, bladder outlet obstruction index (BOOI), and bladder contractility index (BCI) determined by multi-channel urodynamics. Validation of the fidelity of our MRI techniques is critical for clinical implementation. These MRI protocols can be implemented using standard MRI machines available in most hospitals. The clinical impact is that these methods and validated metrics of normal and impaired bladder function provide physicians with a single, non-invasive test that simultaneously delineates both anatomy and function of the lower urinary tract. This will enable a personalized medicine approach to counseling and selection of treatment based upon a clear understanding of the specific anatomic features and functional changes that impair voiding in individual patients with BPH/LUTS.