Radiation dose reduction in perfusion CT imaging of the brain using a 256-slice CT: 80 mAs versus 160 mAs.

Purpose: To examine CTP of the brain in real patient data after reducing tube current down to 80 mAs to decrease radiation dose.

Methods: CTP was acquired in 60 suspected stroke patients with 80 (n: 30) or 160 (n: 30) mAs. Data were analyzed retrospectively by two independent readers. SNR, perfusion maps and image quality were compared in hypoperfused and non-affected areas.

Results: SNR was significantly higher in CTP with 160 mAs compared to 80 mAs (p < 0.001) in non-affected regions, but there was no significant difference in hypoperfused regions. Overall, images with 80 mAs were rated worse than the ones with 160 mAs (3.0 ± 0.7 versus 4.0 ± 0.7), however, still as sufficient to detect proximal vessel occlusions.

Conclusion: Tube current of 80 mAs is still sufficient for the detection of perfusion deficits of proximal vessel occlusions.