Evaluation of the particulate concentration in a gelatin-based phantom for sonographically guided lesion biopsy.

Objectives: The purpose of this study was to determine the particulate concentration in a gelatin-based ultrasound phantom for lesion biopsy at 6 cm in depth to reduce visualization of the biopsy needle in the near field, simulating subcutaneous fat and tissue echogenicity, and maintain target lesion visualization.

Methods: Four gelatin-based phantoms with cornstarch at concentrations of 4, 8, 12, and 16 g/L and an anechoic gelatin target at 7 cm in depth were rated on a 5-point scale by readers for visibility of the target lesion, similarity of near-field to abdominal subcutaneous fat echogenicity, and visibility of a 22-gauge spinal needle in the phantom. A timed sonographically guided localization task was performed on the anechoic target by 4 radiology residents using the 22-gauge spinal needle. Results were analyzed by comparative statistical analysis.

Results: An increasing particulate concentration did not alter the similarity of near-field to abdominal subcutaneous fat echogenicity (P = .6) but did significantly reduce visibility of the anechoic target at a cornstarch concentration of 16 g/L (P = .04) and the 22-gauge needle at 12 g/L (P = .03). Decreased visualization of the needle or target lesion did not affect the time for needle localization of the anechoic target (P = .96).

Conclusions: The optimal ultrasound phantom cornstarch concentration was 12 g/L to reduce visualization of the spinal needle, simulating subcutaneous fat echogenicity while maintaining target lesion visualization.