Improvement of image quality and radiation dose of CT perfusion of the brain by means of low-tube voltage (70 KV).

OBJECTIVES

To investigate the feasibility of 70 kV cerebral CT perfusion by comparing image quality and radiation exposure to 80 kV.

METHODS

Thirty patients with suspected cerebral ischemia who underwent dual-source CT perfusion were divided into group A (80 kV, 150 mAs) and group B (70 kV, 150 mAs). Quantitative comparisons were used for maximum enhancement, signal-to-noise index (SNI), and values of cerebral blood flow (CBF), cerebral blood flow (CBV), mean transit time (MTT) on CBF, CBV, and MTT images, and radiation dose from these two groups. Qualitative perfusion images were assessed by two readers.

RESULTS

Maximum enhancement for group B was higher than group A (P < 0.05). There were no significant differences between the two groups for SNI on CBF and CBV maps (P = 0.06 - 0.576), but significant differences for MTT when SNI was measured on frontal white matter and temporo-occipital white matter (P < 0.05). There were no differences among values of CBF, CBV, and MTT for both groups (P = 0.251-0.917). Mean image quality score in group B was higher than group A for CBF (P < 0.05), but no differences for CBV (P = 0.542) and MTT (P = 0.962). Radiation dose for group B decreased compared with group A.

CONCLUSIONS

70 kV cerebral CT perfusion reduces radiation dose without compromising image quality.

KEY POINTS

• Radiation dose is a key concern with the increased using cerebral CT perfusion. Cerebral CT perfusion of 70 kV reduces radiation dose without compromising image quality. • A 70-kV protocol could be used for cerebral CT perfusion.