Implementation of shear wave elastography on pediatric cardiac transducers with pulse-inversion harmonic imaging and time-aligned sequential tracking

Abstract

Monitoring myocardial stiffness changes with shear wave elastography (SWE) has promising potential for assessing chemotherapy-induced cardiotoxicity for pediatric cancer patients. While ultrasound B-scan with adult cardiac probes on children is commonly acceptable, SWE can be challenging due to the narrow intercostal spaces of children, which hinders the effective transmission of the push beam and detection beam for shear wave generation and shear wave detection. This study aimed at addressing this challenge by implementing cardiac SWE on a pediatric cardiac probe (P7-4) with pulse-inversion harmonic imaging (PIHI) and time-aligned sequential tracking (TAST). The performance of the proposed pediatric cardiac SWE sequence (P7-4 PIHI-TAST) was systematically compared with an adult cardiac transducer equipped with the same PIHI and TAST cardiac SWE sequence (P4-2 PIHI-TAST), and a pediatric cardiac SWE sequence with fundamental imaging TAST shear wave detection (P7-4 Fundamental-TAST). In vivo transthoracic scans in healthy pediatric volunteers demonstrated substantial improvement of shear wave signal quality using the P7-4 PIHI-TAST sequence, as compared to the adult P4-2 PIHI-TAST sequence and the pediatric P7-4 Fundamental-TAST sequence. The results showed higher increase in SWE success rate among younger children when using the pediatric transducer. Also agreeing with previous studies, this study demonstrated that PIHI shear wave detection could substantially improve the shear wave signal quality as compared to fundamental imaging shear wave detection.

Pediatric Cardiac Shear Wave Elastography for Quantitative Assessment of Myocardial Stiffness: A Pilot Study in Healthy Controls

“…The details of the cardiac SW elastography sequence have been previously described (Song et al 2014b(Song et al , 2015(Song et al , 2016. Briefly, two cardiac SW elastography sequences, one based on an adult cardiac transducer (P4-2; Philips Healthcare, Andover, MA, USA) and the other based on a pediatric cardiac transducer (P7-4; Philips Healthcare), were developed and used in this study.…”

“…The adult transducer was preferred due to the large range of imaging depth. However, it was challenging to robustly generate and detect SW signals with the adult transducer for patients with narrow intercostal spaces; the narrow rib gap causes severe acoustic shadowing to the myocardium that blocks effective transmission of both the push and detection beams (Song et al 2015). Figure 8 shows several examples of comparisons between the adult (P4-2) and pediatric (P7-4) transducers.…”

“…We also reported the first transthoracic cardiac SW elastography results from in vivo adult humans (Song et al 2013(Song et al , 2014b(Song et al , 2016. To alleviate the acoustic shadowing caused by the narrow intercostal spaces of young pediatric patients, we recently developed cardiac SW elastography on a pediatric cardiac transducer and demonstrated significant improvement of SW signal quality over an adult cardiac transducer (Song et al 2015). At present, because no pediatric cardiac SW elastography results have been reported, the clinical feasibility and performance of pediatric cardiac SW elastography remain unknown.…”