Efficacy of 'fine' focal spot imaging in CT abdominal angiography.

OBJECTIVES

To assess the efficacy of fine focal spot imaging in calcification beam-hardening artefact reduction and vessel clarity on CT abdominal angiography (CTAA).

METHODS

Adult patients of any age and gender who presented for CTAA were included. Thirty-nine patients were examined with a standard focal spot size (SFSS) of 1 × 1 mm in the first 3 months while 31 consecutive patients were examined with a fine focal spot size (FFSS) of 1 × 0.5 mm in the following 3 months. Vessel clarity and calcification beam-hardening artefacts of the abdominal aorta, celiac axis, superior mesenteric artery, inferior mesenteric artery, renal arteries, and iliac arteries were assessed using a 5-point grading scale by two blinded radiologists randomly.

RESULTS

Cohen's Kappa test indicated that on average, there was substantial agreement among reviewers for vessel wall clarity and calcification artefact grading. Mann-Whitney test showed that there was a significant difference between the two groups, with FFSS performing significantly better for vessel clarity (U, 6481.50; p < 0.001; r, 0.73) and calcification artefact reduction (U, 1916; p < 0.001; r, 0.77).

CONCLUSION

Fine focus CT angiography produces images with better vessel wall clarity and less vessel calcification beam-hardening artefact.

KEY POINTS

Focal spot size affects the spatial resolution of a CT system. Fine focus CTAA produces images with improved vessel wall clarity. Fine focus CTAA is associated with fewer calcification beam-hardening artefacts. Fine focus CTAA may improve accuracy in assessment of luminal stenosis.