川井 夫規子, 伊東 紘一, 谷口 信行, 中村 みちる

Fukiko KAWAI, Kouichi ITOH, Nobuyuki TANIGUCHI , Michiru NAKAMURA

自治医科大学臨床病理学教室

Department of Clinical Pathology, Jichi Medical School

キーワード : Echo intensity, Frequency dependent attenuation (FDA) , Siderotic liver, Tissue characterization, Ultrasound

We sought to estimate iron content in human siderotic livers from degree of frequency dependent attenuation (FDA) and level of echo intensity. FDA values were measured by the spectral-shift zero-crossing method. Echo levels were determined by subtracting echo intensity of a standard graphite-agar phantom from that of a liver sample represented by an echo-intensity histogram. First, we used a 3.5 MHz convex transducer to measure FDA values of livers in vivo in patients with hematologic diseases that are often associated with iron deposition in that organ. FDA values were higher in patients with aplastic anemia, leukemia, and myelodysplastic sysndrome than in patients with idiopathic thrombocytopenia and hereditary spherocytosis. Second, we used a 7.5 MHz annular array transducer to measure FDA values and echo levels of sectioned livers obtained from patients who had died of similar hematologic disorders and other diseases. Degree of iron deposition in sectioned livers was graded by microscopy, and iron content was quantitated according to the method of Foy. FDA values correlated closely with iron content as well as with histologic grade. Echo level, on the other hand, had no correlation with iron content. We conclude that FDA can be used to estimate hepatic iron content noninvasively when echo level is normal.