The Application Of Split-bolus MDCT Enhancement In Renal Clear Cell Carcinomas

Objective:To retrospectively evaluate the evaluation of diagnosis and preoperational TNM stage of renal clear cell carcinomas following split-bolus multidetector computed tomographic (MDCT) enhancement and the change of effective radiation dose.Methods:Between January2012and December2012we recruited90patients who underwent CT enhancement examination for renal mass. Patient consent was granted. MDCT enhancement was performed using64slices Light Speed VCT (GE, American). Contrast medium injection was performed using Irich medical injector through anticubital vein. In all patients the first acquisition was without IV contrast material from the adrenal gland to the inferior pole of kidney. In44patients (experimental group, mean age=58.34years;15females;29males), split-bolus MDCT enhancement was performed. After the first acquisition,45mL of ioversol (320mgI/ml,) was injected IV at the rate of4mL/s. When the CT value of the ROI in the aorta abdominalis increased into100HU, the corticomedullary phase (CMP)was acquired. Additional55mL of ioversol (320mgI/ml,) was injected IV at the rate of4mL/s210seconds after the CMP. The third set of images was acquired70seconds after the second injection, yielding images in a combined nephrographic and excretory phase(N-EP). In another46patients(control group, mean age=59.30years;16females;30males),100ml of ioversol (320mgI/ml,) was injected IV at the rate of3mL/s. When the CT value of the ROI in the aorta abdominalis increased into100HU, the corticomedullary phase (CMP)was acquired. The nephrograpgic phase(NP) and excretory phase(EP) was acquired respectively40seconds and180seconds after CMP. Images were independently reviewed by two abdominal imaging staff radiologists. SPSS19.0software was used to statistical analysis.Results:1. Compare to the control group, tumors CMP CT value decreased in the experimental group, and there is no significant difference (P=0.064); there is a significant difference of tumors’CT value between the N-EP and NP (P=0.000); there is no significant difference of tumors’CT value between the N-EP and EP (P=0.105) 2. There is no significant difference of renal cortex’s CT value between the experimental group CMP and the control group CMP (P=0.510). Renal parenchyma’s CT value obviously decreased in N-EP compared to NP, and obviously increased compared to EP. The differences are significant (respectively P=0.000, P=0.001)3. In the experimental group, the preoperational tumor T stage in CT kept well consistency with pathological T stage(K=0.820, P<0.01). In the control group, the preoperational tumor T stage kept well consistency with pathological T stage(K=0.824, P<0.01). The overall accuracy rate of MDCT was86.4%and87.0%respectively and the difference between two groups was insignificant (P=0.934).There is no lymphatic metastasis in both CT and operation.4. Renal arteries’CT value in experimental group and control group were169.87±47.69HU and190.08±54.43HU respectively, and the difference was significant (P=0.009). In experimental group,34(77.3%)patients’VR images could display renal arteries, while46(100%) in control group (P=0.000). In MIP images,14(31.8%) patients showed1-2level branches of renal arterie and30(68.2%) showed3-4level branches of renal arteries in experimental group, while in control group6(13.0%)showed1-2level branches and40(87.0%) showed3-4level branches (P=0.032). In experimental group, one or more supply arteries of tumors were showed in15patients,6patients had one accessory renal artery.8showed the early branching of the main renal artery. In control group one or more supplying arteries of tumors were showed in20patients,5patients had one or more accessory renal arteries.10patients showed the early branching of the main renal artery.5. In experimental group, the average effective dose was15.25mSv. There is30%less than the radiation effective dose from the control group.Conclusions:The split-bolus CT enhancement of renal can display renal clear cell carcinomas and renal parenchyma well, which is enough to make diagnosis and TNM stage. At the same time, the effective dose is decreased obviously.