3 T-乳腺MRIにおけるsection select gradient reversal法併用拡散強調画像の脂肪抑制法の検討

摘要

This study evaluates fat suppression of diffusion-weighted imaging (DWI) using section select gradient reversal (SSGR) technique in clinical images on 3 T breast MRI. A total of 20 patients with breast cancer were examined at a Philips Ingenia 3 T MRI. We acquired DWI with SPAIR, SSGR-SPAIR, STIR, and SSGR-STIR. We evaluated contrast between the fat region and lesion, the coefficient of variance (CV) of the fat region and the apparent diffusion coefficient (ADC) of normal breast tissue and lesion. The contrast between the fat region and lesion was improved with SSGR technique. The CV of the fattest region did not have any significant difference in SPAIR technique (p＞0.05), but it was significantly decreased in the STIR technique using SSGR technique (p＜0.05). Positive correlation was observed in ADC value between SPAIR and other fat suppression techniques (SSGR-SPAIR, STIR, SSGR-STIR). DWI using SSGR technique was suggested to be effective on 3 T breast MRI.%乳腺magnetic resonance imaging(MRI)は病変の質的診断，病変の存在診断，病変の拡がり診断の三つの役割がある.その乳腺MRIにおける拡散強調画像は腫瘍の良悪性の鑑別や乳癌の検出，乳癌の術前化学療法の治療効果判定などに用いられており，特に有用なシーケンスのひとつである.乳房は脂肪を多く含む臓器であるために，拡散強調画像は脂肪抑制が不可欠で脂肪抑制を併用することにより脂肪組織と病変部のコントラストが改善するが，一方で画像の不均一やケミカルシフトアーチファクトが診断の妨げとなる可能性がある.特に3Tesla(3T)では，1.5Tと比較して理論上2倍のsignal-to-noiseratio(SNR)が得られるが，磁場不均一の影響を受けやすく，脂肪抑制不良による画像の不均一が生じるといった問題がある.