原発性肺癌におけるMRI診断の有用性 : 主病巣の病理組織像との対比を中心に  [in Japanese] Magnetic Resonance Imaging in Peripheral Lung Cancer  [in Japanese]

目的.MRI画像解析を病理学的所見と対比しその有用性を検討した.対象と方法.2005年5月から2006年5月までに当センター呼吸器外科において手術を施行した原発性肺癌52症例のうち,肺野末梢型病変で術前にMRIを施行した45例を対象とした.使用したシーケンスはSTIR法,呼吸同期下高b値拡散強調画像(DWI),ダイナミックスタディーである.結果.腺癌35例と非腺癌10例の比較では各シーケンスの所見に有意差を認めなかった.3cm以下の腺癌27例を対象として,仮に生物学的な悪性度の違いからNoguchi分類のType A+Bを非浸潤癌として一群に,Type Cを初期浸潤癌-Type D+E+Fを浸潤癌として定義し比較検討した. DWIスコアが4,もしくはダイナミックで急峻な立ち上がりを示す病変を浸潤陽性と判定するとsensitivityが94.4%,specificityが66.6%,accuracyが85.2%であった.結語.末梢型肺腺癌に対するMRI画像は病変の質的診断に有用であり,とりわけ高b値拡散強調画像は病変の悪性度を見極めるのに有用であると思われる.

Objectives. We evaluated the usefulness of magnetic resonance imaging (MRI) by comparison of MRI studies and pathological findings in lung cancer patients. Materials and Methods. From May 2005 to May 2006, 52 lung cancer patients underwent surgical operation in our division. Forty-five patients, each with a preoperatively recognized peripheral lung lesion underwent the MRI study. Short TI inversion recovery (STIR), high b-value diffusion-weighted imaging (DWI) with free breathing scanning and dynamic MRI studies were performed. Results. There was no statistically significant difference between adenocarcinoma (n = 35) and other carcinomas (n = 10) on MRI findings. Twenty-seven adenocarcinomas (less than 30 mm in diameter) were histologically diagnosed as follows: 9 patients with bronchioloalveolar carcinoma (BAC), 12 patients with advanced BAC, and 6 non-BAC cases (adenocarcinoma without a BAC component) group. When the lesions demonstrated a strong enhancement (steep type) on dynamic studies or showed a strong signal (score 4) intensity on DWI, we judged them to be positive (indicating invasion). Sensitivity, specificity and accuracy were 94.4%, 66.6%, and 85.2%, respectively. Conclusion. The MRI studies permitted the acquisition of more detailed information on peripheral lung adenocarcinomas, and high b-value DWI is valuable as a supporting tool in evaluating the grade of malignancy.