Staging and differential diagnosis of renal cell carcinoma: a comparison of magnetic resonance imaging (MRI) and computed tomography (CT)

Abstract

33例の腎腫瘍に対しMRI, CTを施行し, stagingおよび鑑別診断における意義について検討した.33例の内訳は腎癌29例, 腎血管筋脂肪腫3例, 腎癌と鑑別の難しかった腎盂癌1例である.stagingの正診率は両者に差は認めなかった.静脈浸潤, リンパ節転移, 隣接臓器への浸潤に関してはMRIの方が正確な傾向があったが, 腎周囲脂肪織への浸潤に関してはMRIは僅かに正確であったに過ぎなかった.また, 鑑別診断の目的で, MRIで%コントラスト(腎腫瘍のintensity/腸腰筋のintensity×100)を計算した.clear cell typeの腎癌ではT1強調画像における%コントラストは, 100前後, T2強調画像では大部分の症例で50以下を示したのに対し, spindle cell typeの腎癌ではT1画像では109であったが, T2画像では65～85と高値を示した.腎血管筋脂肪腫では明らかに脂肪成分と思われる部分以外の部位で%コントラストを計算したところ, T1画像では3例とも50以下, T2画像では2例で50以上, 他の1例は21～38の値を示した.このように症例は少ないが, %コントラストを計算することによってある程度鑑別診断が可能であると予想された

The usefulness of magnetic resonance imaging (MRI) was compared with that of computed tomography (CT). Twenty-nine patients with renal cell carcinoma, 3 with angiomyolipomas and 1 with renal pelvic cancer, were examined by both MRI and CT. MRI and CT showed similar results in staging cases of renal cell carcinoma. However, MRI may be more sensitive in detecting the venous extension, metastatic adenopathy, and adjacent organ invasion. In predicting the involvement of perinephric fat, however, MRI is only marginally superior to CT. To demonstrate the usefulness of MRI in differentiating renal cell carcinoma from other renal tumors, the density of renal tumor and that of the psoas muscle were determined using a densitiometer, and the percent (%) contrast (the intensity of the renal tumor/the intensity of the psoas muscle X 100) was calculated. In most patients with clear cell type renal carcinoma, the % contrast value in the T1 weighted images was about 100. In the T2 weighted images, the maximum value of the % contrast value was 50 or less in most patients. In one patient with spindle cell type (sarcomatoid type) carcinoma, the % contrast value was 109 in the T1 weighted images, but was 65-85, at most, in the T2 weighted images. In patients with renal angiomyolipomas, the % contrast values were calculated exclusive of the fatty components. The % contrast value of the T1 weighted images was 50 or less in all 3 patients, and that of the T2 weighted images was 50 or more in 2 patients and 21-38 in the others.(ABSTRACT TRUNCATED AT 250 WORDS)