Use of contrast-enhanced computed tomography to measure clearance per unitrenal volume: A novel measurement of renal function and fractional vascular volume

The iodinated contrast agents used for computed tomography (CT) have pharma cokinetics similar to inulin and can measure physiological indices, such as clearance per unit renal volume (alpha/V) and fractional vascular volume ( fvv), Clinical experience with these techniques is, however, scanty, and th e present study explored their potential in subjects with and without renal dysfunction. In a series of subjects, a single slice of kidney was scanned sequentially after the bolus injection of contrast material. Time-attenuat ion curves were constructed, and alpha/V and fvv were calculated using a Pa tlak graphic analysis, In the first part of the study, 50 normal kidneys in 35 subjects (aged 21 to 75 years) were studied. In the second stage, alpha /N was compared with glomerular filtration rate (GFR) measurements in 24 pa tients with diabetes (aged 28 to 84 years) with or without renal dysfunctio n. In normal kidneys, alpha/V averaged 0.49 +/- 0.11 mL/min/mL and fvv aver aged 35% +/- 12%, These values agree with literature data obtained using ot her techniques. A negative correlation was seen between age and alpha/V (r = 0.66; P < 0.0001), but not fvv. In patients with diabetes, a strong corre lation was observed between renal clearance values, calculated from CT and corrected for renal volume, and GFR (r = 0.87; P < 0.0001). Dynamic CT can provide quantitative renal physiological information on a regional basis no ninvasively, (C) 1999 by the National Kidney Foundation, Inc.