The 64-MSCT study of relationship between renal corticomedullary differentiation, contrast between renal cortex and medulla, renal cortex and medulla CT peak value with the single renal function in hydronephrotic kidney

Abstract

Objective To study 64-MSCT perfusion imaging features about renal corticomedullary differentiation, contrast between renal cortex and medulla(CMC), renal cortex and medulla CT peak value in normal and hydronephrotic kidneys, and to explore the relationship between them and the unilateral renal function. Methods Thirty-six patients with obstructive nephrohydrosis underwent 64-MSCT perfusion scanning. The split renal glomerular filtration rates (GFR) of their kidneys were measured by SPECT renal dynamic imaging. The 72 kidneys were divided into groups of normal renal function group, mild and severe renal impairment groups according to GFR. Renal corticomedullary differentiation on CT images was graded as clear, obscure, part clear. The CT intensity of cortex and medulla was measured in order to calculate contrast between renal cortex and medulla (CMC). Using Pearson correlation test, the correlation between them and renal GFR were examined. Resets (1) In the 24 kidneys of normal group, all kidneys showed clear CMD. In the 21 kidneys of mild renal impairment group, 14 kidneys showed clear CMD,2 showed obscure CMD and 5 showed part clear of CMD. In the 27 kidneys of severe renal impairment group, 7 kidneys showed clear CMD, 5 showed obscure CMD and 15 showed part clear of CMD. (2)The CMC of normal group was 0. 62±0. 20, while it was 0. 52±0. 14 and 0. 37±0. 11 for mild renal impairment group and severe renal impairment group CMC respectively. The CMC had positive linear correlation with GFR (r=0.536,P <0.05). (3)The renal cortex and medulla CT peak value of normal group were (133 ± 22) and (104 ± 16) HU; The renal cortex and medulla CT peak value of mild renal impairment group were (91 ± 29) and (76 ± 25) HU ; The renal cortex and medulla CT peak value of severe renal impairment group were (68 ± 24) and (57 ± 21) HU (F = 42. 76 and 32. 68, P < 0. 05). The renal cortex and medulla CT peak value had positive linear correlation with GFR (r = 0. 672 and 0. 623, P < 0. 05). Conclusions The CMC and the renal cortex and medulla CT peak value all degrade when kidney function decreases in patients with obstructive nephrohydrosis. The CMC and the renal cortex CT peak value of obstructive nephrohydrosis had positive linear correlation with GFR. So they are valuable in evaluating the unilateral renal function of hydronephresis. Key words: Kidney calculi; Tomography; X-ray computed; Kidney cortex; Kidney medulla