Purpose
The safety of acoustic radiation force impulse (ARFI) elastography, which applies higher acoustic power with a longer pulse duration (PD) than conventional diagnostic ultrasound, is yet to be verified. We assessed the ARFI-induced lung injury risk and its relationship with peak rarefactional pressure amplitude (PRPA) and mechanical index (MI).
Methods
Eighteen and two rabbits were included in the ARFI (0.3-ms push pulses) and sham groups, respectively. A 5.2-MHz linear probe was applied to the subcostal area and aimed at both lungs through the liver for 30 ARFI emissions. The derated PRPA varied among the six ARFI groups—0.80 MPa, 1.13 MPa, 1.33 MPa, 1.70 MPa, 1.91 MPa, and 2.00 MPa, respectively.
Results
The occurrence of lung hemorrhage and the mean lesion area among all samples in the seven groups were 0/6, 0/6, 1/6 (1.7 mm2), 4/6 (8.0 mm2), 4/6 (11.2 mm2), 5/6 (23.8 mm2), and 0/4 (sham), respectively. Logistic regression analysis showed that derated PRPA was significantly associated with lung injury occurrence (odds ratio: 207, p < 0.01), with the threshold estimated to be 1.1 MPa (MI, 0.5). Spearman’s rank correlation showed a positive correlation between derated PRPA and lesion area (r = 0.671, p < 0.01).
Conclusion
This study demonstrated that the occurrence and severity of ARFI-induced lung hemorrhage increased with a rise in PRPA under clinical conditions in rabbits. This indicates a potential risk of lung injury due to ARFI elastography, especially when ARFI is unintentionally directed to the lungs during liver, heart, or breast examinations.
