Elastography is a recommended technique for breast cancer specialists. With just short training, oncologists and physicians can acquire the same degree of competence as a ultrasound specialist in the ultrasonic diagnosis of breast cancer. Yet until recently, diagnoses based on strain imaging lacked objectivity. To provide greater objectivity in assessing elasticity, our group developed a new quantitative parameter called the Fat-Lesion Ratio (FLR).
The FLR is defined as the ratio obtained by dividing the mean strain of fat by the mean strain of a hypo-echoic lesion. The strain of subcutaneous fat is determined from a circular area bound by the skin and mammary glands. The strain of a lesion, meanwhile, is determined from a circular area bound by the inner margin of the hypo-echoic area.
The subjects of this study included 695 patients with hypo-echoic lesions (not over 2 cm in diameter) who underwent examinations by elastography between January 25, 2005 and September 26, 2008. Among these, patients, 305 had breast cancer and 390 had benign disease.
The mean FLR in breast cancer (12.4) was considerably higher than the mean FLR in benign disease (4.2). When applying a cutoff point of 5.2, we obtained a sensitivity of 76.8%, specificity of 78.9%, and accuracy of 77.8%. The area under the ROC curve was high (0.832), with a sensitivity, specificity, and accuracy of 80.7%, 74.1%, and 77.8% respectively. FLR was effective for clinical diagnosis, with high diagnostic objectivity irrespective of the experience of the examiners