Combining Quantitative 3D Subharmonic Imaging and Clinical Assessments for Accurate Characterization of Breast Masses

This multi-center study evaluated the ability of contrast-enhanced, nonlinear 3D ultrasound imaging to characterize indeterminate breast lesions using quantitative parametric maps and clinical assessments. In total 236 women with biopsy-proven breast lesions were enrolled in this study. Following B-mode and power Doppler imaging (PDI), an ultrasound contrast agent (Definity®, Lantheus Medical Imaging, N Billerica, MA, USA) was administrated. Contrast-enhanced 3D harmonic imaging (HI; transmitting/receiving at 5.0/10.0 MHz) as well as 3D subharmonic imaging (SHI; transmitting/receiving at 5.8/2.9 MHz) were performed using a modified Logiq 9 scanner (GE Healthcare, Waukesha, WI, USA) with a 4D10L probe. Five radiologists blinded to the reference independently scored the imaging modes using a 7-point BIRADS scale. Parametric volumes were constructed from time-intensity curves for vascular heterogeneity, perfusion (PER as the slope of the curve) and area under the curve (AUC) based on individual voxel values in the lesion. ROC analysis were applied to assess diagnostic accuracy with biopsy results as the reference. Out of the 236 cases, 219 were successfully scanned and biopsies resulted in 164 (75%) benign and 55 (25%) malignant lesions. 3D HI showed flow in 8 lesions (5 benign and 3 malignant), whereas 3D SHI visualized flow in 83 lesions (58 benign and 25 malignant). Hence, extracting quantitative parameters was restricted to the SHI volumes that demonstrated sufficient flow for processing. Diagnostic accuracy for the quantitative SHI parameters ranged from 0.52 to 0.75. Diagnostic accuracies from the clinical assessments ranged from 0.55-0.94 for baseline ultrasound, 0.52-0.93 for PDI, 0.59-0.85 for HI and 0.55-0.91 for SHI. The best logistical regression model achieved an accuracy of 0.91. In conclusion, combining quantitative SHI perfusion estimates and conventional B-mode imaging may increase the accuracy for characterizing indeterminate breast masses.