骨肉腫の治療効果判定における画像評価法の検討

Radiological Evaluation of the Response to Chemotherapy for Osteosarcoma

　骨肉腫の61例に対し，X線，血管造影，MRI，²⁰¹Tl，^99mTc-MIBIを施行し，術前化学療法の画像評価法について検討した．X線では硬化像，皮質の修復，血管造影では腫瘍血管の変化，MRIでは骨腫瘤縮小率，²⁰¹Tl，^99mTc-MIBIでは集積低下率から反応群と無反応群に分類した．全例に対し病理学的評価を行い，壊死率90％以上を反応群とした．病理学的評価を基準とした感度，特異度，正確度は，X線で81.0％，19.0％，60.3％，血管造影で77.1％，20.0％，60.0％，MRIで82.1％，69.0％，75.4％，²⁰¹Tlで81.5％，68.0％，75.0％，^99mTc-MIBIで76.7％，70.6％，74.5％であった．画像検査の総合的評価は感度88.9％，特異度84.0％，正確度86.9％であった．

　Sixty-one patients with osteosarcoma were examined by radiographs, angiograms, MRI, ²⁰¹Tl and ^99mTc-MIBI scintigram to evaluate their response to preoperative chemotherapy.　All patients were classified as either responders or non-responder according based on the imaging findings.　The radiographs were evaluated according to the degree of sclerotic change and cortical recovery, and the angiograms were evaluated according to the degree of vascular change.　MR images were evaluated according to the rate of extraskeletal mass reduction.　The ²⁰¹Tl and ^99mTc-MIBI scans were evaluated by the percentage reduction of the uptake ratio.　All patients were evaluated on the basis of a pathological examination of the resected specimens.　We also devised a combined radiological scoring system according to the predictive power of each type of diagnostic image and investigated the correlation between the radiological evaluation and the pathological evaluation.　Sensitivity, specificity, and accuracy were 81.0%, 19.0%, and 60.3%, respectively for the radiographs；77.1%, 20.0%, and 60.0%, respectively, for angiograms；82.1%, 69.0%, and 75.4%, respectively for MRI；81.5%, 68.0%, and 75.0%, respectively, for ²⁰¹Tl scans；76.7%, 70.6%, and 74.5% for ^99mTc-MIBI scans；and 88.9%, 84.0%, and 86.9%, respectively, for the combined radiological evaluation.