Reverberant wavefield characterization and directional filtering for penile vibro-elastography: a pilot feasibility...

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Urology

Background:

• Penile vibro-elastography faces challenges due to reverberant shear wavefields in the corpus cavernosum (CC).
• These reverberations can inaccurately bias shear wave speed (SWS) estimates, impacting stiffness assessment.
• Accurate CC stiffness measurement is crucial for diagnosing and managing erectile dysfunction (ED).

Purpose of the Study:

• To evaluate local phase velocity imaging with wavefield band-pass filtering (LPVI-WBF) for CC stiffness assessment in post-prostatectomy ED.
• To compare LPVI-WBF against phase gradient (PG) and time-of-flight (TOF) methods in estimating SWS.
• To determine the reliability of different methods under reverberant conditions.

Main Methods:

• Six patients with post-prostatectomy ED underwent penile vibroelastography across four visits.
• Shear wave speed (SWS) was measured in flaccid and erect states using LPVI-WBF, PG, and TOF at 100, 150, and 200 Hz.
• Simulations were conducted to assess accuracy and frequency stability under varying wavefield conditions.

Main Results:

• Reverberant components significantly affected penile acquisitions, with traveling wave energy absent in 59% of cases.
• LPVI-WBF yielded physiologically consistent SWS estimates (erect > flaccid), unlike PG and TOF which showed reversed results.
• LPVI-WBF demonstrated minimal frequency dependence (dispersion exponent α = 0.048), indicating accurate assessment of weakly viscoelastic CC tissue.

Conclusions:

• LPVI-WBF provides reliable SWS estimates consistent with expected CC biomechanics in post-prostatectomy ED patients.
• Traditional methods (PG, TOF) failed to provide accurate CC stiffness measurements due to reverberant wavefield contamination.
• Further phantom validation and multi-directional wavefield simulations are recommended to fully establish LPVI-WBF accuracy.