Complicated Renal Cystに対するCT,MRIによる鑑別診断の比較検討

Abstract

嚢胞性腎腫瘤のうち良悪性の鑑別が困難であったcomplicated cyst 12例に対しUS, CT, MRIおよび血管造影検査を施行した.血管造影所見は全例hypovascularもしくはavascular patternを呈し, 診断的価値は低かった.腎細胞癌の検出においてはdynamic studyを含むCT診断が優れていると考えられたが, false positiveとなった症例を5例認めた.MRIは濃度分解能が優れており, 特に出血性嚢胞やmultilocular cystの診断に有用と思われた.しかし現時点ではCTにて悪性を疑われた嚢胞性腫瘤に対しては補助診断としてMRIを施行し, 腎保存手術の適応を考える上で参考にするといった利用方法が望ましいと思われた

We report 12 cases of renal cystic lesions that could not be diagnosed preoperatively. Sonography, computed tomography (CT), magnetic resonance (MR) imaging, and angiography were performed in all cases. Angiography was not helpful in evaluating cystic lesions, because all cystic lesions were hypovascular or avascular within the cystic mass. CT was useful in depicting the fine structural abnormalities, and especially bolus-contrast CT study was useful in the differentiation of cystic renal cell carcinoma from simple renal cyst. However, there were 5 false positive cases. MR imaging is superior to CT in distinguishing a hemorrhagic cyst or multiloculated cystic mass. In conclusion, CT is currently the primary imaging modality for evaluating complicated renal cysts, and surgical exploration is warranted for the undiagnosed cystic lesion by CT. However, MR imaging also has an important role in detecting the benign complicated cyst. Therefore if complicated cyst is thought to be benign by MR imaging, parenchyma-sparing surgery should be considered preoperatively.