Assessment Of Split Renal Function With Spectral Detector Computed Tomography Iodine Quantification Versus Renal Dynamic Imaging

Objective:We aimed to explore a method that can evaluate split renal function by spectral detector computed tomography（SDCT）using iodine quantification and compare it with glomerular filtration rate（GFR）measured by^99mTechnetium-diethylene triaminepentaacetic acid(^99mTc-DTPA)renal dynamic imaging Gates method,so as to find its potential clinical value.Methods:We reviewed 101 patients who underwent both multiphasic enhanced renal SDCT and^99mTc-DTPA renal dynamic imaging Gates GFR within two weeks from January 2021 to September 2021 in the First Hospital of Shanxi Medical University.SDCT scans were performed using a normal enhanced abdominal protocol.Renal volumes（V）,mean CT number（HU）,and mean iodine concentration（IC）were delineated manually.The cumulative amount of iodine contrast media（K）was the product of IC and V.Clearance of single kidney was calculated using a simplified“two-point Patlak plot.”The patients’kidneys were divided into three groups according to Gates GFR:normal（Gates GFR≥40m L/min）,mild-to-moderate（20m L/min≤Gates GFR<40m L/min）,and severe（Gates GFR<20m L/min）groups.SDCT parameters were compared between groups using one-way analysis of variance or Kruskal-Wallis H test.Correlation between SDCT parameters and Gates GFR was analyzed using Spearman’s coefficient.Receiver operating characteristic（ROC）curve analysis was used to determine diagnostic performance for clearance of single kidney to distinguish between normal and mild-to-moderate impaired renal function,as well as mild-to-moderate and severe impaired renal function.Bland–Alterman plot was created between clearance of single kidney and Gates GFR.Results:The V,mean HU of arterial phase-HU（t1）,mean HU of parenchymal phase-HU（t2）,mean IC of arterial phase-IC（t1）,mean IC of parenchymal phase-IC（t2）,K of arterial phase-K（t1）,K of parenchymal phase-K（t2）and the clearance of single kidney between the groups were statistically significant（F/Z=47.997,48.572,45.284,48.596,49.628,70.152,91.880,and 91.892,respectively;all P（27）0.001）.V,HU（t1）,HU（t2）,IC（t1）,IC（t2）,K（t1）,K（t2）,and the clearance of single kidney were correlated with Gates GFR（r=0.538,0.468,0.476,0.486,0.504,0.683,0.743,and 0.752,respectively;all P<0.001）.The area under curve（AUC）for the clearance of single kidney distinguishing between normal and mild-to-moderate damaged split renal function was 0.760,the sensitivity and specificity were 0.736 and 0.698,and the cutoff value was 450mg;The AUC for the clearance of single kidney distinguishing between mild-to-moderate and severe damaged split renal function was 0.928,the sensitivity and specificity were 0.463 and 0.934,and the cutoff value was 240 mg.The Bland-Altman plot showed 8 samples,that is,3.96%（<5%）outside the consistency range of 95%,and the error was acceptable.Conclusion:All parameters of SDCT were positively correlated with Gates GFR obtained by^99mTc-DTPA renal dynamic imaging,which could reflect split renal function.The correlation between clearance of single kidney from SDCT and Gates GFR was the highest and consistent,which could realize quantitative classification of split renal function.It is meaningful in clinical work.