Effect of renal depth estimation on residual renal GFR in dynamic renal scintigraphy of renal occupied lesion

Objectives: The aim of this study was to evaluate the effect of the renal depth estimation in calculation of residual renal GFR in renal occupied lesions.

Methods: Forty cases were selected from the patients who had renal occupied lesions and underwent 99mTc-DTPA SPECT/CT renal dynamic imaging with low-dose abdominal CT in General Hospital of Ningxia Medical University during Jan. to Dec. 2018. According to the results of pathology, patients were divided into benign group (12 cases) and malignant group (28 cases). The renal depths of both groups were calculated by CT measurement and Tonnesen formula separately, and then the results were introduced to the Gates formula to calculate the split renal GFR respectively. CKD-EPI formula was used as the standard method to calculate the total GFR of the patients. The renal depth and GFR within the group were analyzed by Paired-sample T Test, and the difference between the two groups was analyzed by Independent-sample T Test.

Results: There were significant statistical differences of the renal depth and corresponding GFR between CT method and Tonnesen method in both benign and malignant group (P<0.05). When comparing the corresponding GFRs between benign and malignant group, no statistical differences were found (P>0.05). No significant difference of the GFR between CT method and CKD-EPI method was found (P>0.05). Tonnesen-GFR was statistically lower than EPI-GFR (P<0.05) in all patients.

Conclusions: The measurement of renal depth using CT method may improve accuracy of the GFR estimation for patients with occupied lesions. GFR were no statistical difference between benign and malignant renal mass. Tonnesen-GFR underestimated the GFR in patients with renal mass.