Effect of intravenous contrast agent volume on colorectal cancer vascular parameters as measured by perfusion computed tomography

Aim

To determine the effect of two different contrast agent volumes on quantitative and semi-quantitative vascular parameters as measured by perfusion computed tomography (CT) in colorectal cancer.

Materials and methods

Following ethical approval and informed consent, eight prospectively recruited patients with proven colorectal adenocarcinoma underwent two separate perfusion CT studies on the same day after (a) 100ml and (b) 50ml of a 340mg/ml iodinated contrast medium, respectively. Quantitative (blood volume, blood flow, permeability surface area product) and semi-quantitative (peak enhancement, time to peak enhancement) tumour vascular parameters were determined using commercial software based on distributed parameter analysis and compared using t-testing.

Results

Tumour blood volume, blood flow, and permeability surface area product were not substantially different following the injection of 100ml and 50ml contrast medium: 6.12 versus 6.23ml/100g tissue; 73.4 versus 71.3ml/min/100g tissue; 15.6 versus 15.3ml/min/100g tissue for 100 and 50ml, respectively; p>0.05. Tumour peak enhancement and time to peak were significantly greater following the injection of 100ml versus 50ml contrast medium: 41.2 versus 28.5 HU; 16.1 versus 11.8 s for 100ml and 50ml, respectively; p=0.002; p=0.0003.

Conclusion

Quantitative parameters do not appear to change substantially with a higher contrast agent volume suggesting a combined diagnostic staging–perfusion CT study following a single injection is feasible for colorectal cancer.