The enhancement of the renal cortex and medulla and the renal function: a correlative study of conventional CT scan with glomerular filtration rate

目的 探讨肾脏常规皮质、髓质CT平扫与增强扫描与肾小球滤过率(GFR)的关系.方法 回顾性分析35例单侧肾后性梗阻性肾积水患者16层螺旋CT平扫与增强皮质期影像.以SPECT的GFR为参考标准,将35例患者按照肾功能结果分为4组:正常组,轻、中、重度肾功能损害组.测量计算患肾肾皮、髓质增强程度及各项比值.采用单因素方差分析比较上述指标的差异,采用Pearson法与GFR进行相关性分析.结果 肾功能正常组及轻、中、重度受损组患肾肾皮质增强程度(CT皮增-CT皮平)分别为(154.98±28.70)、(122.67±39.32)、(81.30±32.94)和(57.60±23.49)HU、增强后患侧与健侧皮质的CT值比值(CT患皮/CT健皮)分别为0.97±0.09、0.79±0.18、0.64±0.24和0.51±0.13、患侧及健侧髓质的CT值比值(CT患髓/CT健髓)分别为0.98±0.26、0.89±0.18、0.86±0.31和0.75±0.28、患侧皮髓质CT值比值(CT患皮/CT患髓)分别为2.76±0.35、2.35±0.79、1.83±0.68和1.73±0.28、患侧皮髓质CT值比值与健侧皮髓质CT值比值之比[(CT患皮/CT患髓)/(CT健皮/CT健髓)]分别为1.00±0.28、0.89±0.34、0.75±0.17和0.69±0.14,差异有统计学意义(P<0.05).肾皮质CT值增强程度与GFR呈高度正相关(r=0.887,P<0.01),肾髓质CT值增强程度与GFR无相关性(r=0.203,P>0.05),患侧与健侧皮质增强CT比值与GFR呈高度正相关(r=0.872,P<0.01),患侧及健侧髓质增强CT比值与GFR呈中度正相关(r=0.504,P<0.01),患侧皮髓质增强CT值比值与GFR呈高度正相关(r=0.772,P<0.01),患侧皮髓质增强CT比值与健侧皮髓质增强CT比值之比与GFR呈中度正相关(r=0.663,P<0.01).以皮质期CT患皮/CT患髓高(≥2.60)、较高(2.20～2.59)、中(1.80～2.19)、低(<1.80)为判断肾功能正常、轻度损害、中度损害与重度损害的标准,对35例患肾功能SPECT结果对照,两种分组的符合率为80.0%.结论 GFR分级定量分析,不同GFR分组各肾皮质相关CT增强指标差异有统计学意义,且与GFR呈正相关,其中患侧皮髓质增强CT值比值适用于对单、双侧梗阻患者单肾功能进行评价,可对肾后性梗阻积水肾功能损害作出半定量诊断,相对于CT灌注简单方便,X线辐射剂量低.Objective To study the relationship between the enhancement of renal cortex and medulla during the conventional CT scans with and without contrast enhancement and the renal glornerular filtration rate (GFR). Methods Thirty five cases with unilateral posternal obstructive hydronephrosis According to GFR, the 70 kidneys were divided into 4 groups: normal, slightly impaired, moderately impaired and severely impaired. In the cortical phase of enhanced CT scan, the enhancing intensity of the renal cortex and medullar was measured and following measures were calculated: CTce - CTcp, CTmc -CTmp,ratio of enhancement of affected and unaffected renal cortex and medullar, and the ratio of those of each case: CTac/CTnc, CTam/CTum, CTac/CTam, CTnc/CTnm, (CTac/CTam) / (CTuc/CTum). The differences of these measures in different groups were analyzed with one-way ANOVA and their correlation with GFR was studied with Pearson test. The best indicator to reflect enhancement of renal cortex was selected from these measures, and all the kidneys were divided into 4 groups accordingly: strong, less strong, medium and weak. Then its consistency with GFR groups were calculated. Result (1) The differences of CTce - CTcp ( 154. 98 ± 28. 70 ), ( 122.67 ± 39. 32 ), ( 81.30 ± 32.94 ) and ( 57.60 ±23.49) HU respectively, CTac/CTuc 0. 97 ±0. 09, 0. 79 ±0. 18, 0. 64 ±0. 24 and 0. 51 ±0. 13 respectively,CTam/CTum 0. 98 ±0. 26, 0. 89 ±0. 18, 0. 86 ±0. 31 and 0. 75 ±0. 28 respectively, CTam/CTum 2. 76 ±0. 35,2. 35 ± 0. 79, 1. 83 ± 0. 68 and 1.73 ± 0. 28 respectively, CTac/CTam and ( CTac/CTam)/( CTuc/CTum) 1.00 ±0. 28,0. 89 ±0. 34, 0. 75 ±0. 17 and 0. 69 ±0. 14 respectively of different GFR groups were evident( P < 0. 05 ) . ( 2 ) Positive correlation was found between GFR and CTce-CTcp ( r = 0. 887, P <0. 01 ), CTac/CTuc ( r = 0. 872, P < 0. 01 ), CTam/CTum ( r = 0. 504, P < 0. 01 ), CTac/CTam ( r =0. 772, P < 0. 01 ), (CTac/CTam) / (CTuc/CTum) ( r = 0. 663, P < 0. 01 ). ( 3 ) Selecting CTac/CTam to reflect enhancement of renal cortex, the diseased kidneys can be divided into groups of strong ( CTac/CTam ≥2. 60); less strong (2. 20 ≤CTac/CTam <2. 60); medium ( 1.80 ≤CTac/CTam <2. 20); and weak ( CTac/CTam < 1. 80). The consistency with GFR grouping was 80. 0%. Conclusions There is significant correlation between renal cortex-related indicators and GFR, especially CTac/CTam, which can be used as the indicator of renal function in patients with unilateral or bilateral postrenal obstructive hydronephrosis. The conventional contrast enhanced CT scan can be taken as a semi-quantitative method of GFR measuring with relative low X-ray dosage compared with CT perfusion.中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)09958-9624