The importance of mammographic imaging has grown tremendously from 1990-2000. The main reason is that one out of eight women dies due to breast cancer in the U.S.A. alone. There are several imaging modalities that give useful diagnostic information when used for scanning a patient's breasts (see Fig. 23.4, left); the most widely used are x-ray mammography; ultrasound; magnetic resonance (MR) (see Weinreb and 147 references therein, and Lucas-Quesada et al. and references therein); SPECT and lately using infrared breast imaging. Advanced MR technology has played a promising and clinically useful role in the early treatment of early breast lesion detection when using contrast agents injected into the human body, such as Gad (gadolinium-dithylene-triamine-penta-acetate).
Perfusion MRI has played a vital role in early cancer detection, using a combination of MR imaging and contrast agent technology. There are several types of perfusion analysis systems, and these systems can be applied to different parts of the body. The most common areas include brain, breast, heart, liver, and kidney. This chapter is focused only on the breast using MR technology; however, the reader is referred to the articles by other authors in the area of perfusion analysis for other body parts. (For brain perfusion imaging, see Refs. 17 and 18; for SPECT cardiac perfusion, see Refs. 19-21; and for cardiac ultrasound perfusion, see Ref. 22.)
Given these pre- and postcontrast gadolinium (Gad) MR breast images, uptake curve estimation holds diagnostic utility in clinical mammography. The methodology for a complete breast examination is still under investigation by most of the engineering-in-medicine institutions; however, the standard practice is to estimate the uptake curve in the Gad-absorbed regions depending on tissue characteristics. The rate of absorption of Gad by a lesion depicts the type of lesion it might be, and also can give an indication of the malignancy stage. The differences in contrast enhancement rate can be used to distinguish between benign and malignant lesions. In breast perfusion analysis, first, the patient's breasts are scanned prior to administering contrast. Then, the gadolinium contrast agent is injected and the patient's breasts are scanned again, using the identical MR scan (see Refs. 23-25 on MR breast perfusion). Oncologists and radiologists can possibly classify the type of malignancy by looking at quantitative characteristics such as mean and standard deviation of the tissue signal enhancement.
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