Inter- and intra-observer variability in prostate definition with tissue harmonic and brightness mode imaging

Area of Science:

• Medical imaging
• Radiology
• Oncology

Background:

• Accurate prostate volume delineation is crucial for radiation therapy planning.
• Transrectal ultrasound (TRUS) is a key imaging modality for prostate assessment.
• Evaluating different ultrasound modes, like harmonic (H) and brightness (B), is essential for optimizing image quality and consistency.

Purpose of the Study:

• To compare the relative utility of tissue harmonic (H) and brightness (B) transrectal ultrasound (TRUS) images for prostate delineation.
• To assess interobserver and intraobserver variation in prostate contouring using both imaging modes.

Main Methods:

• Ten early-stage prostate cancer patients were selected for TRUS imaging in B and H modes.
• Prostates were contoured by an experienced radiation oncologist and five trained observers.
• Prostate volumes and midgland slice areas were calculated, and inter- and intraobserver variability was evaluated.

Main Results:

• Observer-delineated volumes showed agreement with the radiation oncologist (p > 0.05).
• Prostate volumes and midgland areas were significantly smaller with H mode compared to B mode (p = 0.008 and p = 0.006, respectively).
• H mode demonstrated greater interobserver consistency for small prostate glands (≤35 cc), while B mode was more consistent for large glands (≥35 cc).

Conclusions:

• Tissue harmonic imaging offers superior inter- and intraobserver agreement for defining prostate volume in small to medium-sized glands.
• H mode provides no additional advantage in large glands; B mode offers more consistent estimates in these cases.
• The utilization of harmonic imaging for prostate delineation appears judicious, particularly for smaller prostates.