泌尿器科的腎疾患における Xenon-133 washout 法による腎血流量測定の臨床的有用性の検討

Abstract

Renal blood flow was measured in 22 patients with a variety of renal abnormalities using the xenon-133 washout technique. Compartmental analysis was employed to analyze the xenon washout curve. Three components were defined: a first component taken to represent cortical blood flow; a second component taken to represent medullary blood flow; and a third component assumed to represent blood flow in perirenal tissues. Measurements were performed in four patients with renal hematuria thought to have normal renal function on the basis of normal serum creatinine levels and normal PSP excretion. Cortical blood flow in this group averaged 407.5±51.5 ml/100 g/min or 77.3±4.1% of the distribution of xenon. The second component in these patients averaged 111.8±2.7ml/100 g/min or 16.4±2.4%, and the third component averaged 9.5±2.7 mi/100g/min or 6.3±2%. We used the I-131 Hippuran renogram to estimate renal plasma flow and mean transit time through the kidney. The renal vasculature was analyzed after a renal arteriogram using Hollenberg's criteria. We found that the first component of xenon-133 washout values did not correlate well with renal plasma flow (r=0.59), mean transit time (r=0.55), renal vasculature grading (r=0.53), or the ratio of the diameter of the renal artery to that of the abdominal aorta (D RA/AO, r=0.50). However, a cortical distribution percent of xenon was associated with a decreased renal plasma flow (r=0.81), an increased mean transit time (r=0.81), a decrease of the ratio of the diameter of the renal artery to that of the abdominal aorta (r=0.67), and an increased abnormality of renal vasculature grading determined by Hollenberg's technique (r= -0.81). In patients with localized lesions, such as carcinoma, hydronephrosis, or tuberculosis of the kidney, we found a discrepancy between renal plasma flow, estimated from the renogram, and cortical blood flow, determined by the xenon-133 washout technique. Cortical blood flow values were several fold higher than those estimated from the renal renogram. This occurred in patients with renal tuberculosis and hydronephrosis. The xenon-133 value for cortical blood flow was also inappropriately higher than that calculated from the renogram in a patient with renal cell carcinoma. A patient with hyperaldosteronism in whom renal blood flow was normal when calculated from the renogram findings, had very high values for cortical blood flow determined by the xenon-133 washout technique. Another patient with renal artery stenosis showed increased values for cortical blood flow determined by the xenon-133 washout technique some two weeks after repair of his lesion, at which time his blood pressure was normal. However, measurements of renal plasma flow calculated using the renogram did not become normal until one month following surgery. Patients with unilateral renal disease, sufficiently severe that intravenous pyelography showed very poor visualization, had very low values for cortical blood flow determined by the xenon-133 washout technique. In such patients, nephrectomy may be the treatment of choice. This contrasts with patients with moderately decreased renal blood flow and markedly decreased renal plasma flow, where renal constructive surgery might be the treatment of choice. We conclude that estimation of renal blood flow by the xenon-133 washout technique can provide a good index of renal hemodynamics. The test can be performed conveniently and can provide significant information to supplement that obtained by other methods. We believe that further clinical evaluation of this method is warranted.