| Purpose:The kidney depth measured on CT images was used as the evaluation standard to evaluate the influence of kidney depth calculated by Tonnesen formula and Li Qian formula on glomerular filtration rate measured by Gates method,and the relationship between kidney depth and waist circumference.Materials and methods:From August 2017 to September 2018,93 patients underwent renal dynamic imaging in the first aff-iliated hospital of medical college of shihezi university,including 49 males and 44 females,aged 16-89 years,with an average age of 55.68±14.53 years.All patients were grouped according to waist circumference criteria proposed in the guidelines for the prevention and control of overweight and obesity in Chinese adults.Normal waist circumference group:A total of 42 patients with male waist circumference<85cm and female waist circumference<80cm were collected,including 19 males with an average age of 49.11±17.39 years,and 23 female patients was 57.87±15.07 years.Waist circumference abnormal group:A total of 51 cases,with male waist circumference?85cm and female waist circumference?80cm were collected,including 30 male cases,were collected with an average age of 55.33±12.83 years,and 21 female patients was 59.71±12.11 years.All patients'age,height,weight,waist circumference and other personal information were measured and recorded on the day of examination.99mTc-dtpa was selected as the marker,and dynamic renal imaging was performed immediately after elbow vein pellet injection in 93 patients,and CT scan of renal area was performed after the completion of the renal dynamic imaging while keeping the body position unchanged.After all examinations,Tonnesen formula and Li Qian formula were used to calculate the predicted values of left and right kidney depth,and the left and right kidney depth were measured on CT images.The calculated renal depth results of the three groups were substituted into the image processing workstation to calculate the corresponding left and right kidney eGFR.SPSS 20.o and MedCalc v18.11.3 statistical software were used for statistical analysis of the data.The kidney depth calculated by Tonnesen formula and Li Qian formula and the corresponding eGFR measured by CT and the corresponding eGFR were matched by t-test.All values were expressed by mean(x±s).There was significant difference between the two groups(P<0.05).Bland-altman method was used for consistency analysis of normal distribution data.Bias were used for all data,i.e.,the standard deviation of the mean(d±Sd)of the difference between the two formulas and the corresponding eGFR,and the standard deviation of the mean(+1.96)of the difference between the two formulas and the actual CT results.(d±1.96Sd)indicated that P<0.05 had significant difference.Result:In the normal waist circumference group,the left and right kidney depths calculated by Li Qian formula were the closest to those measured on CT images,with no statistical difference(t=0.59,1.23,P>0.05).The left and right kidney depths calculated by Tonnesen formula were lower than those measured by CT,and the difference was statistically significant(t=-12.49,-15.17,P<0.01).In the waist circumference abnormal group,the renal depth calculated by Li Qian formula was lower than that measured by CT,and the difference was statistically significant(t=-3.97,3.74,P<0.01).The renal depth calculated by Tonnesen formula was significantly lower than that measured by CT,and the difference was statistically significant(t=-14.64,-12.81,P<0.01).In the normal waist circumference group,the eGFR calculated by substituting the left and right kidney depths calculated by Li Qian formula into the eGFR calculated by Gates'formula was the closest to the eGFR calculated by substituting the kidney depths measured on CT images into the eGFR calculated by Gates' formula,with no statistical difference(t=1.06,0.93,P>0.05).However,the eGFR obtained by the left and right kidney depth calculated by the Tonnesen formula was lower than that obtained by the CT value(t=-10.31,-12.98,P<0.01).In the waist circumference abnormal group,the eGFR of left and right kidney obtained by Li Qian formula was lower than that obtained by the CT measurement value(t=-3.81,-4.09,P<0.01).The left and right kidney eGFR obtained by the Tonnesen formula was significantly lower than the eGFR obtained by the CT value(t=-11.91,-11.79,P<0.01).Consistency analysis the normal waist circumference group:The renal depth calculated by Li Qian formula and corresponding eGFR between the kidney depth measured by CT and corresponding eGFR all showed bias very small.The degree of kidney depth bias was left kidney 0.06 ± 0.55,right kidney 0.09 ± 0.47,and the boundary of renal depth consistency was left kidney-1.03?1.05 and right kidney-0.83?1.02.The degree of eGFR bias was 1.01±7.72 in the left kidney,1.54±7.67 in the right kidney,and the consistency boundary was-14.1?16.16 in the left kidney and-13.49?16.57 in the right kidney.The consistency limit of all the above data was basically within the acceptable range of clinical diagnosis and treatment,and there was no statistical difference in the analysis results,with a good consistency,P>0.05.The kidney depth calculated by the Tonnesen formula and between the renal depthmeasured by CT and corresponding eGFR were significantly biased.The degree of kidney depth bias was left kidney-1.29 ± 0.59,right kidney-1.27 ± 0.52,the limit of renal depth consistency was left kidney-2.44?-0.14,right kidney-2.27?-0.26,the degree of eGFR bias was left kidney-14.32±7.90,right kidney-16.00±7.60,the limit of eGFR consistency was left kidney-29.82?-1.17,right kidney-1.05?-30.95.The consistency limits were partly beyond the clinical acceptable range,and the analysis results showed significant statistical difference with poor consistency,P<0.01.Consistency analysis the waist circumference abnormal group:Kidney depth calculated by Li Qian formula and Tonnesen formula,kidney depth measured by corresponding eGFR and CT,and comparison of corresponding eGFR all showed some degree of bias,and the bias of Tonnesen formula was significant.The degree of kidney depth bias of Li Qian formula was left kidney-0.66±1.17,right kidney-0.67±1.22,and the consistency boundary was left kidney-2.92?1.59,right kidney-2.99±1.65.The eGFR bias of Li Qian formula was left kidney-7.86±14.18,right kidney-8.55±13.88,and the consistency boundary was left kidney-35.58?19.85,right kidney-35.73?18.61.According to Tonnesen formula,the degree of renal depth bias was left kidney-2.41±1.12,right kidney-2.28±1.17,and the consistency boundary was left kidney-4.62?-0.20,right kidney-4.60?0.03.The degree of eGFR bias in Tonnesen formula was left kidney-23.81±13.71,right kidney-23.86±13.41,and the consistency boundary range was left kidney-50.67?3.04,right kidney-50.15?2.43.All the results showed statistical difference,P<0.01.Conclusion:The results of this study showed that when male waist circumference<85cm and female waist circumference<80cm,Li Qian formula can be used to better predict the depth of the kidney,thus significantly improving the accuracy of GFR calculation by Gates method.When male waist circumference is greater than or equal to 85cm and female waist circumference is greater than or equal to 80cm,the calculation results of Li Qian formula and Tonnesen formula will show a certain degree of deviation.In this case,the kidney depth can be obtained by CT images or other methods for correction,so as to improve the accuracy of GFR calculation by Gates method. |
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