dialysis kidney, ultrasound examination, acquired cystic disease of the kidney, renal cell carcinoma
過去において透析腎は腎不全の終末像であり萎縮した腎臓の評価が主であった．しかしその後，長期透析に関連する後天性腎嚢胞（Acquired cystic disease of the kidney: ACDK）の発生と腎癌の関連性が示唆されるようになり，ACDKの診断が重要になってきた．さらに最近では導入患者の高齢化と透析期間の長期化が重なり腎癌診断の重要性が増している．そのため透析腎に対する超音波検査は現在ほぼ必須検査として多くの透析施設において実施される．一方透析導入患者における慢性糸球体腎炎由来患者の減少と糖尿病由来患者の増加による腎不全の原疾患の構成割合の変化や導入前治療による修飾などのため透析導入後の腎臓はいろいろな形態を呈するように変化している．このため透析腎の超音波診断では透析腎の経時的変化や原疾患との関連性，先天性と後天性嚢胞腎の違いと嚢胞内出血と腎癌の鑑別，造影エコーによる腎癌診断法について十分に理解した上で検査に臨むことが大切である．
In the past, kidneys after long-term dialysis represented a terminal state of renal failure, for which the care provided remained primarily atrophy assessment. Later, however, it was suggested that the development of acquired cystic disease of the kidney (ACDK) after prolonged dialysis was associated with renal carcinoma, drawing attention to the importance of the diagnosis of ACDK. Furthermore, in recent years, a rise in the age of incident patients has been observed concurrently with longer periods of dialysis, highlighting that the diagnosis of renal carcinoma is increasingly important. For this reason, ultrasonic examination of the kidneys in patients on maintenance dialysis is conducted as a quasi-requisite test in many dialysis centers today. Meanwhile, changes in the breakdown of underlying diseases among incident patients due to decreases in those originally suffering from chronic glomerulonephritis and increases in those with diabetic nephropathy-derived renal failure in combination with other factors, including modifications occurring after treatments provided prior to dialysis, have caused changes in the kidneys leading them to appear in varied forms after dialysis initiation. Based on the above observations, it is important to fully understand changes over time in kidneys on long-term dialysis, their relations with the underlying pathology, differences between congenital and acquired cystic kidneys, differences between cystic hemorrhage and renal tumors, as well as the contrast-enhanced echo techniques for diagnosis of renal carcinoma, before performing ultrasonic diagnosis in patients on prolonged dialysis treatment.