Quantitative correlation of breast tissue parameters using magnetic resonance and X-ray mammography

Abstract

Summary Previous investigators have shown that there is a strong association between the fraction of fibroglandular tissue within the breast as determined by X-ray mammography (per cent density) and breast cancer risk. In this study, the quantitative correlation between per cent density and two objective magnetic resonance (MR) parameters of breast tissue, relative water content and mean T2 relaxation time, as investigated for 42 asymptomatic subjects. Using newly developed, rapid techniques MR measurements were performed on a volume-of-interest incorporating equal, representative portions of both breasts. X-ray mammograms of each subject were digitised and analysed semiautomatically to determine per cent density. (Kelsey et al., 1983).More sensitive risk assessment is provided, however, by quantitative methods of classification based on the relative fraction of fibrogandular breast tissue, known as the per cent density (PD), and also by increasing the number of classification categories to define individuals at highest risk more precisely (Brisson et al., 1982;Warner et al., 1992). A quantitative classification scheme using six categories with PD values of 0%, 0-10%, 10-25%, 25-50%, 50-75% and >75% has been applied recently in a nested case-control study of 332 pairs of women selected from the cohort of women in the mammography arm of the Canadian National Breast Screening Study (Miller et al., 1992a,b). A 6-fold difference in risk was found between the highest and lowest density categories, and the two upper categories accounted for 44% of incident cancers . This result is particularly significant because breast cancer susceptibility genes (Miki et al., 1994; Wooster et al., 1994) account only for approximately 5-10% of breast cancer incidence, and the established risk factors in combination are known to account for only 25-30% of breast cancer incidence (Seidman et al., 1982). The use of quantitative classification schemes indicates clearly that PD is a major risk factor for breast cancer.Semiautomated methods have been developed to calculate PD and other quantitative parameters as continuous variables from digitised mammograms (Byng et al., 1994). These methods substantially reduce the intra-and interobserver variability traditionally involved in classification, are quite insensitive to variations in mammography technique and are strongly correlated with the six-category classification of mammograms by radiologists.The ability to assess breast cancer risk by parenchymal pattern has several applications, e.g. as a tool to study breast cancer aetiology, or to monitor changes in breast cancer risk during interventional studies. Although most investigations of breast parenchymal patterns have used X-ray mammography to date, other non-hazardous imaging modalities can provide similar, and possibly complementary, risk assessment. For example, a qualitative four-category classification scheme has been developed for breast ultrasonography that correlates with the area of the breast occupied by mammographic density ...

Association between Transillumination Breast Spectroscopy and Quantitative Mammographic Features of the Breast

“…Although water associated absorption correlates with fibroglandular tissue (32,33), contributions from oxyhemoglobin are expected in less proliferating dense tissue (31). Increasing values of t 4 suggest some contributions from water as well as oxyhemoglobin (23).…”

“…TiBS score t 2 was also inversely associated with the dense area of the breast among premenopausal women only. Decreasing values of t 3 suggest a higher water content, which correlates with higher-density tissue (32,33), as well as greater contributions from deoxyhemoglobin (that is, lower oxygen saturation) due to increased cellular proliferation and metabolism in denser tissue (28,31). Decreasing values of t 2 indicate greater deoxyhemoglobin and oxyhemoglobin absorption (that is, total hemoglobin content) as a result of increased tissue vascularization in higherdensity tissue (31).…”

“…[24][25][26][27][28][29][30][31]. In breast tissue, stromal and epithelial tissues are characterized by increased scattering and water-associated absorption and concomitant decreased lipid associated absorption, larger total hemoglobin content, and lower oxygen saturation (31)(32)(33).…”

Classification of breast computed tomography data

“…Even so there have been attempts to estimate breast tissue composition by analysis of mammograms 30-37 and MRI data. [5][6][7][8]38 Breast CT is capable of producing high-resolution volumetric images of pendant breasts. 10 Breast CT images are subjectively of higher quality than the images from projection mammography.…”

Differences in breast density assessment using mammography, tomosynthesis and MRI and their implications for practice

“…MRI has been used to calculate the water content of a human breast via slices or slabs and with segmentation of 3D images with tailored sequences [24][25][26][27][28][29][30]. It has been shown that percent MRI-density correlates strongly with mammographic PD; however, MRI, as also discussed above for DBT, has been shown to underestimate breast density compared with conventional mammography.…”