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来可靠地区分患者的乳腺良恶性病变。病理评估是目前获得明确诊断的唯一途径。本研究将使用磁共振波谱（MRS）和极高磁场（4特斯拉）的新方法来区分乳腺病变的恶性和良性。所需的特异性将从质子（1H） mrs非侵入性测量的生化特性中获得。这项工作将进一步研究早期的发现，即在1H光谱中含有胆碱化合物（Cho）的3.2 ppm可能是乳腺病变恶性肿瘤的标志。据推测，假阳性诊断可能是由3.2 ppm的共振引起的，这种共振不是由Cho引起的，而是由脂质或其他迁移率降低和横向弛豫时间短的大分子（T2）引起的。在3.2 ppm时，大脑的1H光谱显示出大分子共振。在本项目中，测量的内在T2的差异应该允许3.2 ppm的大分子和脂质共振与自由Cho区分开来，从而消除假阳性。所提出的MRS方法所提供的提高的信噪比和4特斯拉磁场将显著降低假阴性诊断的发生率。作为表征乳腺病变的另一种方法，也将研究MRS测量乳腺病变中葡萄糖代谢的能力，通过静脉注射富含稳定13C同位素的葡萄糖来检测13C标记的乳酸。乳房病变将通过动态增强二维MRI和高分辨率三维MRI显示。在活检或手术切除之前，将对临床发现的可疑乳房病变进行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.