REGIONAL VARIATIONS OF ULTRASONIC INTEGRATED BACKSCATTER IN NORMAL AND MYOPATHIC LEFT-VENTRICLES - A NEW MULTIVIEW APPROACH

The purpose of the present study was to determine whether the cyclic v ariation of integrated backscatter is measurable and quantifiable in a ll left ventricular walls and whether the information obtained using b oth parasternal and apical transducer positions can be used to identif y changes in myocardial structure and contractility. The cyclic variat ion of integrated backscatter was measured from the parasternal long-a xis, apical four-chamber and two-chamber views in 26 patients with idi opathic dilated cardiomyopathy (mean age 58 +/- 9 years, ejection frac tion 29 +/- 10%) and compared with information obtained from 30 aged-m atched healthy volunteers. For each subject, the cyclic variation of i ntegrated backscatter was calculated from 16 predetermined regions-of- interest located within the myocardium of the basal and mid-segments o f the left ventricle imaged from the long-axis view and also the basal mid and apical left ventricular segments imaged from the two apical v iews. The cyclic variation of integrated backscatter was found to be p resent in 100% of the analysed regions-of-interest in healthy voluntee rs and in 87.5% of the analysed regions-of-interest in patients with i diopathic dilated cardiomyopathy. The mean value of cyclic variation o f integrated backscatter, averaged from all regions-of-interest in the idiopathic dilated cardiomyopathy group, was significantly reduced co mpared to that in the healthy volunteers group (3.2 +/- 2.5 dB [mean /- SD] vs 4.8 +/- 2.9 dB, P<0.0001). Additionally, the healthy volunte ers group demonstrated marked regional variability in the magnitude of cyclic variation of integrated backscatter which closely followed the regional changes in the contractile function of the normal heart. The se regional differences in the magnitude of the cyclic variation of in tegrated backscatter were only partially retained in the idiopathic di lated cardiomyopathy group, and suggest that a multi-view approach of the recording of cyclic variation of integrated backscatter can be of value to differentiate normal from myopathic myocardium and to quantif y regional differences in myocardial contractile performance throughou t the left ventricular walls.