Ultrasound-Guided Biopsy of Focal Lesions Using Three-Dimensional Ultrasound With a Matrix Array Transducer

Abstract

To investigate the feasibility of biopsy-guided 3-dimensional (3D) ultrasound (US) with a matrix array transducer (3D US-MAT), using the lateral and/or elevation tilt modes. Both inexperienced and experienced examiners performed biopsy experiments using a freehand technique on agar-based phantoms with 2-dimensional (2D) US guidance and 3D US-MAT guidance allowing real-time biplane imaging, using the lateral tilt mode and/or elevation tilt mode. Each phantom contained 4 targets of different sizes, and there were 3 different types of phantom, each having a different distance between the target and the surface. In every session, each target was aimed at 3 times, with 3 different distances between the transducer and puncture site, which resulted in 36 biopsies (3 biopsies per target × 4 targets × 3 phantoms, each of which was uniquely identified by size, depth, and angle). This procedure was carried out by each of 2 examiner twice by 2D US and twice by 3D US-MAT, resulting in paired data for each biopsy and each examiner. Target variables were target specimen length (TSL), procedure time, and agreement between the TSL of the first and second procedure by each examiner with identical biopsy parameters as a reliability measure. The intraexaminer agreements between the TSLs with the 3D US-MAT in both inexperienced (r = 0.84) and experienced (r = 0.93) examiners were higher than with the 2D US (r = 0.59 with P = 0.0066, and r = 0.87 with P = 0.06, respectively). However, the procedure time with the 3D US-MAT was significantly longer than with the 2D US. The TSL were significantly longer with 3D US-MAT than with 2D US for both the examiners; the inexperienced examiner (P < 0.001) benefited more than his experienced colleague (P = 0.024). In addition, the 3D US-MAT had significant benefits for the acquisition of TSL with small target diameters and for targets with shallow locations; with more acute puncture angles for both the examiners (all P < 0.05). Using a 3D US-MAT guidance improves the reliability and precision of biopsies, particularly under difficult conditions and for inexperienced examiners.