Early Experience Studying Cerebral Aneurysms with Rotational and Threedimensional Angiography and Review of CT and MR Angiography Literature

Depiction of branch vessels arising from intracranial aneurysm sacs: Time-of-flight MR angiography versus CT angiography

BACKGROUND

To evaluate the sensitivity, specificity, and accuracy of time-of-flight MR angiography (MRA) compared with CT angiography (CTA) for detection of branch vessels arising from the intracranial aneurysm sac, using a 3-tesla MR scanner and an area detector CT scanner.

METHODS

Fifty patients with an intracranial aneurysm (25 patients with a branch vessel arising from the sac and 25 patients without) underwent rotational intraarterial digital subtraction angiography (rotational DSA), MRA, and CTA. The following six image sets were assessed using a 3-point scale for the existence of a branch vessel: (1) volume rendering with MRA (MRA-VR); (2) CTA-VR; (3) source images with MRA; (4) source images with CTA; (5) VR and source images with MRA ('MRA-VR+source images'); and (6) 'CTA-VR+source images'. Each set comprised the data of all 50 patients. Three radiologists then performed consensus review and calculated the sensitivity, specificity, and accuracy for MRA and CTA; rotational DSA was considered as the gold standard.

RESULTS

Higher accuracies were obtained in review using VR+source compared with both VR and source alone. In addition, higher accuracies were obtained in review using MRA compared with CTA. The highest accuracy of 0.96 was obtained for 'MRA-VR+source images'; in contrast, accuracy on 'CTA-VR+source images' was 0.86.

CONCLUSIONS

The results show that 3-tesla MRA is an ideal non-invasive imaging examination for detection of a branch vessel arising from an intracranial aneurysm sac. Higher accuracy, especially sensitivity, with MRA compared with CTA was found in ICA, but accuracy with MRA was same as that with CTA in MCA.

3D cerebral angiography: radiation dose comparison with digital subtraction angiography

BACKGROUND AND PURPOSE

As the use of 3D rotational angiography (3D RA) for the evaluation of cerebral vasculature becomes more widespread, it is important to evaluate this imaging method's effect on patient radiation dose. The purpose of the study is to measure 3D RA radiation dose as compared with biplanar digital subtraction angiography (DSA).

METHODS

The distribution and peak skin dose were measured for 3D RA and biplanar DSA by using an anthropomorphic skull phantom. In addition, the cumulative incident dose, summed over all images in each acquisition, was determined. Measurements were acquired for our facility's standard 3D RA acquisition mode (25 degrees /s rotational speed; 162 total frames) and other available acquisition mode selections.

RESULTS

For 3D RA, the skin dose was found to be distributed across the back and sides of the skull with the peak skin dose located at the center of the back of the skull. The peak skin dose for the standard 3D RA acquisition mode was 15 mGy. For a biplanar DSA run, the peak skin dose was 58 mGy, also located at the back of the skull. The cumulative incident dose for the standard 3D RA acquisition mode was 33 mGy, compared with 53 mGy for biplanar DSA.

CONCLUSION

The patient radiation dose for 3D RA is significantly lower than for biplanar DSA, by nearly a factor of 4 in peak skin dose and 40% lower in cumulative incident dose.