A Review Study on the Efficacy of Quantitative DCE-MRI in Breast Lesion Diagnosis

Breast cancer is the most common cancer among women, for which a successful treatment depends in part, on early diagnosis. Accurate differentiation of lesions may greatly affect the outcome of treatment. In this regard, anatomical along with physiological MR imaging modalities, such as dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), diffusion weighted imaging (DWI), and magnetic resonance spectroscopy (MRS) which provide accurate, repeatable and noninvasive physiological biomarkers of tumor growth, have been increasingly used as secondary characterizing tools to ultrasonography (US) and mammography. The aim of this study is to present a thorough review on available scholarly works, especially where quantitative DCE-MRI has been employed for diagnostic decisions on breast cancer, concluding if the modality is either necessary for better sensitivity/specificity, or for a reliable surgery/treatment planning. US and mammography are the conventional screening modalities for breast cancer diagnosis. The overall sensitivity of mammography is 70%90%. However, this sensitivity is variable and can range from as high as 80%98% in women with fatty breast tissue to as low as 30%48% in women with dense breast tissue. Sonographic classification of benign and malignant tumors has a high sensitivity of as high as 98% but a low specificity of about 32%. The low specificity of mammography and US methods and the need for extracting biomarkers, has led to rising interest in employing physiological MR imaging methods for characterizing breast cancers. DCE-MR images can be analyzed in a semi-quantitative (non-model-abased) or quantitative (model-based) approach. The sensitivity and specificity of semi-quantitative DCE-MRI in detecting breast cancer reaches 88.1% and 67.7%, respectively. While it has been proved that DCE-MR imaging features could be useful to noninvasively distinguish highly aggressive breast carcinomas, they are not as useful in discriminating benign from malignant non-mass lesions (such as DCIS). On the other hand, the pharmacokinetic (or model-based) analysis of DCE-MRI can be useful in monitoring and predicting response to therapy, as the changes in tumor vascularization in responder patients precede changes in tumor size, and may better describe tumor response to therapy. Pharmacokinetic model analysis of DCE-MRI data provided a sensitivity and specificity of 100% and 78%, respectively. In comparison with semi-quantitative DCE-MRI, Quantitative DCE-MRI has significantly improved the sensitivity and specificity of breast cancer diagnosis. Other physiological MR imaging alternatives like DW-MRI and MRS have also been employed for breast cancer diagnosis. In a pooled analysis on clinical breast MRS gathered from five independent centers around the world, the sensitivity and specificity of breast MRS were 83% and 85%, respectively. In a study on 78 patients (110 lesions), the sensitivity and specificity of DWI in detection of malignant and benign lesions was reported at 86%. Although the sensitivity and specificity of imaging could be influenced by the selected values of ADC cut-off, the ADC-values may still be used to characterize breast lesions. The diagnosis of breast cancer is a very challenging issue, as early detection may allow for conservative surgery as an alternative to mastectomy. Although mammography and US allow earlier detection of cancers and have been shown to improve the survival of women with breast cancer, with a relatively high sensitivity in women older than 50 years, monitoring the breast cancer is limited by low specificity. DCE-MRI is a powerful imaging tool that has shown utility in delineating the extent of disease in patients with known breast cancer and in screening women at high risk for breast cancer. Semi-quantitative DCE-MRI has high sensitivity but only moderate specificity, because of an overlap between benign and malignant lesions, independent of breast density, tumor type, and menopausal status. Quantitative analysis of DCE-MRI is used by many researchers for detecting and evaluating breast diseases and is a means of increasing the specificity of breast MR examination. MRS of the breast has been proposed as an adjunct to the anatomical MRI examination to improve the specificity of distinguishing malignant from benign breast tumors, however, MRS alone is not suitable in lactating women. Nevertheless, many studies have reported that DWI-MRI may help to differentiate between benign and malignant lesions with good specificity. These findings suggest that incorporating MRS and DW-MRI may increase the overall specificity of quantitative analysis of breast DCE-MRI.