Novel ultrasonic fusion imaging method based on cyclic variation in myocardial backscatter

Quantitative ultrasonic tissue characterisation of the myocardium based on integrated backscatter (IB) has the potential of becoming an effective method for detecting and evaluating myocardial ischaemia. To facilitate IB-based clinical applications, a new imaging method has been developed that combines the anatomical information of a B-mode image with the contractile performance of a selected myocardial region. To produce such a fusion image, a region of interest (ROI) in a B-mode cardiac image was first selected by the user. Algorithms for detection of the endocardium and epicardium were developed, and the resulting mean distance between the computer-detected curve and the manually traced curve was 0.83mm for the endocardium and 0.58mm for the epicardium. The cyclic variation of IB (CVIB) of each myocardial tissue element within the ROI was then calculated over one cardiac cycle. Finally, a grey-scale B-mode image at the end of diastole was displayed as a still image, and the pixels representing the myocardial tissue in the ROI colour-coded according to the corresponding CVIB over the past heart cycle. Both the B-mode image and the colour-coded region were refreshed (up-dated) at the next end-of-diastole. Preliminary results from normal (CVIB= 10-12dB) and ischaemic (CVIB = 5-7 dB) canine hearts are presented that demonstrate the utility of this new imaging method.