中田 典生, 原田 潤太, 福田 国彦

Norio NAKATA, Junta HARADA, Kunihiko FUKUDA

東京慈恵会医科大学放射線医学教室

Department of Radiology, Jikei University School of Medicine

キーワード : Artifacts, Harmonics, Kidney, Nonlinearity parameter (B/A), Ultrasonography

We studied 63 patients with abnormal findings on renal ultrasonography in the attempt to evaluate the clinical usefulness of tissue harmonic imaging in non-contrast enhanced renal ultrasonography. A Hitachi-ATL HDI 5000 ultrasound system with a convex broadband probe (2 to 5 MHz) was used. Renal ultrasound (US) images produced with tissue harmonic imaging (THI) were compared with corresponding images made with conventional fundamental US, and three radiologists (certified by the Board of The Japan Society of Ultrasonics in Medicine) independently compared all 63 cases. We classified US images obtained with THI into four categories: excellent, better, equal, and worse. Four (6.3%) of the 63 cases were classified as excellent; 21 (33.3%), as better; 36 (57.1%), as equal; and 2 (3.2%), as worse. Image quality with THI was improved, especially in cases of cystic lesions (51.2%) and hydronephrosis (60%) and in 1 (33.3%) of the 3 cases of renal cell carcinoma. The advantages of THI included (1) high signal-to-noise ratio, enhanced image contrast, and fewer side-lobe artifacts; and (2) fewer multiple reflection artifacts. THI proved highly useful for evaluating cystic lesions and hydronephrosis in renal ultrasonography, and, moreover, in differentiating between renal cysts and solid renal cell carcinomas. Renal ultrasonography is also playing important clinical roles in the screening of renal cell carcinomas in Japan. We consider THI to be helpful in diagnosing renal lesions in routine examinations because of its high image quality and smaller number of artifacts.