P2B-4 Quantitative Analysis of Contrast Enhanced Subharmonic Breast Images

This project was undertaken to demonstrate that quantitative contrast enhanced subharmonic imaging (SHI) can be used to characterize breast lesions in vivo. A modified Logiq 9 scanner (GE Healthcare, Milwaukee, WI) operating in grayscale SHI mode (transmitting/receiving at 4.4/2.2 MHz) was used to study 14 women with 16 breast lesions (4 malignant). Following grayscale and power Doppler imaging (PDI), an ultrasound contrast agent was administrated for PDI and grayscale SHI. Digital clips were acquired and SHI time intensity curves constructed using ImagePro Plus (Media Cybernetics, Silver Spring, MD). SHI perfusion estimates were determined using a linear relationship based on the slope of the initial SHI uptake (previously established in a canine model). Perfusion was determined within 3 regions of interest, (ROIs) encompassing the centre, the periphery or the entire lesion. Cumulative Maximum Intensity (CMI) images were constructed from SHI through maximum intensity capture of temporal data in consecutive images to better visualize tumor neovascularity. The mean transit time was calculated for each lesion. The degree of vascularity observed with PDI and with contrast-enhanced PDI both correlated with SHI (r² ges 0.40; p < 0.009), but not with each other (r² = 0.18; p = 0.103). Perfusion estimates in the whole lesion were significantly different for malignant and benign tumors (p = 0.04) but not for central and peripheral ROIs (p > 0.32). CMI imaging provided a better depiction of the tortuous angiogenic vascular morphology associated with breast lesions. The mean transit time was lower in malignant than in benign masses (0.72s plusmn 0.19s vs. 1.31s plusmn 0.72s; p = 0.02). In conclusion, quantitative methods for analyzing in vivo grayscale SHI have been tested in breast lesions. Preliminary results indicate that perfusion and mean transit time may improve the characterization of malignant and benign breast masses. However, the curren- t