Objective:

To explore the potential clinical value of spectral detector computed tomography (SDCT) iodine quantification in assessing the split renal function impairment in patients with renal tumor.

Methods:

This retrospective study included 50 patients with renal tumors who underwent both multiphasic enhanced renal SDCT and renal dynamic imaging within two weeks. 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 two groups according to

99m

Tc-diethylene triamine pentaacetic acid (

99m

Tc-DTPA) Gates glomerular filtration rate (Gates GFR): normal (Gates GFR≥40 mL/min)

and impaired (Gates GFR＜40 mL/min) group. SDCT parameters were compared between groups using Kruskal-Wallis H test. Correlation between SDCT parameters and Gates GFR was analyzed using Spearman’s coefficient.Receiver operating characteristic (ROC) curve analysis was performed to determine optimal diagnostic threshold for clearance of single kidney to distinguish between normal and impaired renal function.

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 (

Z

/t=-4.459

2.815

-3.313

2.611

-3.609

-4.395

-5.637

-5.815;

P

＜0.05)；and those parameters were related to Gates GFR (r=0.489

0.339

0.481

0.361

0.531

0.590

0.724

0.740;

P

＜0.001). The

cutoff value of clearance in distinguishing normal from impaired renal function was 543 mg.

Conclusion:

All parameters of SDCT could reflect split renal function

among which the clearance had the highest correlation with Gates GFR and could be used in diagnosis of impaired split renal function

which was meaningful in clinical work.