Imaging assessments of lower urinary tract dysfunctions: Future steps.

Urodynamic tests are the standard diagnostic method for lower urinary tract dysfunctions (LUTD). However, these tests are invasive. The current review describes the noninvasive imaging techniques that have been used to monitor LUTD. The main imaging technologies that have been applied in diagnosing LUTD were 2D ultrasonography, Doppler ultrasonography, and near-infrared spectroscopy (NIRS). Ultrasonographic parameters, such as bladder wall thickness (BWT), detrusor wall thickness (DWT), and ultrasound-estimated bladder weight (UEBW), have been proposed as surrogates for bladder outlet obstruction (BOO) or detrusor overactivity (DO). Few studies have reported diagnostic cut-offs in diagnosing BOO or DO; thus, there is still a need to standardize the measurement method. NIRS can detect the hemodynamic changes related to DO and BOO in real-time, which could be advantageous in clinical practice, but the liability of NIRS to motion artefacts is a limitation. Bladder strain imaging in real-time using 2D ultrasound enables noninvasive estimation of the dynamic changes in the bladder wall during voiding. Many imaging techniques have been used to monitor the urinary bladder during the storage and voiding phases of the micturition cycle. These techniques were either static [i.e., measuring fixed parameters, such as BWT, DWT, UEBW, and intravesical prostatic protrusion (IVPP)] or dynamic (monitoring the structural and hemodynamic changes in the bladder wall in real-time). These techniques are currently being developed and standardized for potential use in diagnosing LUTD in clinical practice.