Semiautomatic method for peak velocity quantification using 4D flow imaging in hypertrophic cardiomyopathy with left ventricular outflow tract obstruction.

OBJECTIVES

The presence of left ventricular outflow tract obstruction (LVOTO) is an important factor in the management of hypertrophic cardiomyopathy. Measurement of left ventricular outflow tract (LVOT) peak velocity on 4D flow cardiac magnetic resonance imaging using current postprocessing methods can be laborious and time-consuming. The purpose of this study was to assess the reliability and reproducibility of a new semiautomatic measurement method.

MATERIALS AND

METHODS

This single-center prospective study included patients who underwent cardiac MRI at 1.5 T for the assessment of hypertrophic cardiomyopathy with left ventricular ejection obstruction as part of their initial assessment or follow-up. A free-breathing kat-ARC accelerated 4D flow sequence was added to the usual protocol. MRI scans were anonymized and analyzed by two observers to quantify LVOT peak velocity using conventional and semiautomatic methods. The duration of postprocessing was recorded for each method.

RESULTS

Twenty-six patients (60.9 ± 11 years, 11 men) were included. Intraobserver agreement was excellent for both methods but was slightly higher for the semiautomatic method than for the conventional method (Intraclass Correlation Coefficient ICC = 0.998 vs 0.905). Interobserver agreement was good for the conventional method (ICC = 0.859) and excellent for the semiautomatic method (ICC = 0.999). In addition, analysis times were significantly shorter with the semiautomatic method (p < 10-3).

CONCLUSION

The semiautomatic method for measuring LVOT peak velocity on a kat-ARC accelerated 4D flow sequence in hypertrophic cardiomyopathy with left ventricular outflow tract obstruction is fast and reproducible. It is an alternative to the conventional quantification method, which is time-consuming and operator dependent.