肺癌の貫壁性心筋転移の診断に123I-BMIPP心筋シンチグラムが有用であった1例

A Case of Transmyocardial Lung Cancer Metastasis diagnosed with 123I-BMIPP Myocardial SPECT

　85歳，男性．1995年9月に他院で肺扁平上皮癌と診断され，放射線療法を50Gy施行された．小康状態を得て外来で経過観察中であったが，1996年6月頃より全身倦怠感を認めたため当院に紹介入院となった．胸部X線写真で心胸郭比の拡大，心電図で肢誘導低電位差を認めたため経胸壁断層心エコー図を施行したところ，心尖部に腫瘍の付着を認めた．付着部位の壁運動は低下していたが，心筋内部のエコー輝度の変化は認めず，貫壁性の心筋転移か否かの鑑別は困難であった．血流を反映するT1では軽度集積低下を認めるのみであったが，脂肪酸代謝を反映するBMIPPでは腫瘍付着部位に一致して欠損を認めた．剖検所見では，BMIPPの欠損部位に一致して貫壁性に心筋転移を認めた．BMIPPは肺癌の左室心筋転移の診断に寄与すると考えられた．

An 81-year-old male was admitted to our hospital with the complaint of increasing general fatigue. He had previously been diagnosed as having lung cancer and treated with radiation (50Gy) to the right lower lung field at another hospital. Chest X-ray revealed right pleural effusion, interstitial shadow in the right lower field and cardiomegaly. ECG showed low voltage in limb leads and negative T wave in leads II, III, aV_F, V₆. Echocardiography revealed slight pericardial effusion and a tumor attached to the left ventricular apex. The wall motion of the left ventricular apex was reduced but there were no differences in gray scales between the apical myocardium and the other myocardium on echocardiography. We could not determine whether the tumor was transmyocardial. ²⁰¹T1 myocardial SPECT, reflected on myocardial perfusion, revealed mildly reduced uptake at the left ventricular apex. ¹²³I-BMIPP myocardial SPECT, reflected on myocardial fatty acid metabolism, showed a defect in that region. We diagnosed this case as transmyocardial metastasis from lung cancer because lung cancer relatively lacked blood supply and metabolized not fatty acids but glucose. Despite treatment, the patient died of ventricular fibril-lation. Autopsy showed the transmyocardial metastatic region at the left ventricular apex. We conclude that ¹²³I-BMIPP myocardial SPECT may be considered diag-nostic of transmyocardial lung cancer metastasis.