MRS AND MRI OF BREAST CANCER AT VERY HIGH MAGNETIC FIELD

目前，没有诊断成像方法提供足够的特异性，以可靠地区分良性和恶性乳腺病变的患者。 病理学评估是目前获得明确诊断的唯一途径。 这项研究将使用磁共振波谱（MRS）的新方法和非常高的磁场（4特斯拉）来区分恶性和良性乳腺病变。 所需的特异性将获得从非侵入性测量质子（1H）MRS的生化特性。这项工作将进一步研究早期的发现，在3.2 ppm的含胆碱化合物（Cho）的存在下，在1H光谱可能是乳腺病变的恶性肿瘤的标志物。 据推测，假阳性诊断可能是由3.2 ppm处的共振引起的，该共振不是由Cho引起的，而是源于迁移率降低和横向弛豫时间（T2）短的脂质或其他大分子。 在脑的~ 1H谱中，在3.2ppm处出现大分子共振。 在本项目中，所测得的内在T2的差异应允许在3.2 ppm的大分子和脂质共振与游离Cho区分开来，从而消除假阳性。所提出的MRS方法和4特斯拉磁场提供的改善的SNR将显著降低假阴性诊断的发生率。 作为表征乳腺病变的替代方法，还将通过静脉注射富含稳定13 C同位素的葡萄糖后检测13 C标记的乳酸盐，研究MRS测量乳腺病变中葡萄糖代谢的能力。将通过动态对比增强二维MRI和高分辨率三维MRI可视化乳腺病变。在活检或手术切除之前，将对临床确定的可疑乳腺病变进行MRI和MRS扫描。与病理结果的相关性将揭示所提出的MRS测量是否提供了准确识别和表征乳腺患者恶性病变所需的额外特异性。

Currently no diagnostic imaging method offers sufficient specificity to reliably differentiate between benign and malignant breast lesions in patients. Pathologic evaluation is presently the only way to obtain a definitive diagnosis. This research will use new methods in magnetic resonance spectroscopy (MRS) and a very high magnetic field (4 Tesla) to distinguish malignant from benign breast lesions. The required specificity will be gained from biochemical properties measured non- invasively with proton (1H) MRS. This work will further investigate the earlier finding that the presence of choline- containing compounds (Cho) at 3.2 ppm in 1H spectra may be a marker for malignancy in breast lesions. It is hypothesized that false-positive diagnoses can result from a resonance at 3.2 ppm that does not arise from Cho, but instead originates from lipids or other macromolecules with reduced mobility and short transverse relaxation time (T2). A macromolecular resonance at 3.2 ppm has been shown to occur in 1H spectra of brain. In the present project, the measured difference in intrinsic T2 should permit macromolecular and lipid resonances at 3.2 ppm to be distinguished from free Cho, thus eliminating false-positives. The improved SNR offered by the proposed MRS methods and the 4 Tesla magnetic field will significantly reduce the incidence of false-negative diagnoses. As an alternative means to characterize breast lesions, the ability of MRS to measure glucose metabolism in breast lesions will also be investigated, by detecting 13C-labeled lactate following an intravenous injection of glucose enriched with the stable 13C isotope. Breast lesions will be visualized by dynamic contrast-enhanced two-dimensional MRI and high resolution three-dimensional MRI. MRI and MRS scans will be performed on clinically identified suspicious breast lesions prior to biopsy or surgical removal. Correlation with pathologic findings will reveal whether the proposed MRS measurements provide the additional specificity needed to accurately identify and characterize malignant lesions in breast patients.