Efficacy of fine focal spot technique in CT graphy of neck.

Objectives: Focal spot size partially defnes spatial resolution of a CT system. Many CT tubes have two focal spot sizes, with the fner one allowing more detailed imaging at the cost of photon intensity and increased heat production. Improved X-ray technology and advancement of various generations of iterative reconstruction allow the use of fne focal spot technique in CT angiography. CT neck angiography (CTNA) has been commonly performed as part of stroke imaging or in the trauma setting. This prospective study aimed to assess the efcacy of fne focal spot scanning in vessel clarity improvement, vessel calcifcation and arterial pulsation artefact reduction on CTNA. Methods and materials: Consecutive adult patients of all ages and genders who presented for CTNA were included. All CTNA were scanned with standard focal spot size (SFSS) of 1 x 1 mm in frst 4 months while the CTNA in the following 4 months with fne focal spot size (FFSS) of 0.5 x 1 mm. Vessel clarity, calcif-cation and arterial pulsation artefact of arch of aorta, brachiocephalic, subclavian, common carotid, carotid bifurcation, internal carotid, external carotid and vertebral arteries were assessed randomly using a 5-point scale by two blinded radiologists. Results were compared. Result(s): There were 43 patients (mean age 60) with 97 calcifed arterial segments in SFSS and 48 patients (mean age 62) with 113 calcifed arterial segments in FFSS. 30 % of patients had > 50% carotid artery stenosis. No occlusion or dissection was found in the remaining arteries. Mann-Whitney test showed FFSS performed signif-cantly better for vessel clarity (U: 48238.50, p < .001,r: 0.556) and calcifcation artefact reduction (U: 2040.50, p < .001,r: 0.564). There was no signifcant reduction for arterial pulsation artefact. Conclusion(s): Fine focal spot technique improves vessel clarity and reduces calcifcation blooming artefact in CTNA. These benefts may potentially improve the assessment of arterial luminal stenosis and vess