Identification of intraplaque haemorrhage in carotid artery by simultaneous non-contrast angiography and intraPlaque haemorrhage (SNAP) imaging: a magnetic resonance vessel wall imaging study

Abstract

Objectives

To investigate the usefulness of Simultaneous Non-contrast Angiography and intraPlaque haemorrhage (SNAP) imaging in characterising carotid intraplaque haemorrhage (IPH) compared with magnetisation-prepared rapid acquisition gradient-echo (MP-RAGE) sequence.

Methods

Fifty-four symptomatic patients (mean age: 63.1 ± 5.7 years, 38 males) with carotid atherosclerosis were recruited and underwent carotid MR imaging. The presence and area of IPH on SNAP and MP-RAGE images were determined. The agreement in identifying IPH and its area between SNAP and MP-RAGE was analysed.

Results

Of 1368 slices with acceptable image quality in 54 patients, 13% and 22.6% were found to have IPH on MP-RAGE and SNAP images, respectively. There was moderate agreement between MP-RAGE and SNAP sequences in identifying IPH (κ = 0.511, p = 0.029). The area of IPH on SNAP images was significantly larger than that on MP-RAGE images (17.9 ± 18.2 mm² vs. 9.2 ± 10.5 mm², p < 0.001). For IPHs detected by SNAP imaging, the area of IPHs also detected by the MP-RAGE sequence was significantly larger than that of IPHs not detected by the MP-RAGE sequence (17.9 ± 19.2 mm² vs. 6.4 ± 6.2 mm², p < 0.001).

Conclusion

Compared with the MP-RAGE sequence, SNAP imaging detects more IPHs, particularly for smaller IPHs, suggesting that SNAP imaging might be a more sensitive tool for identification of carotid haemorrhagic plaques.

Key Points

• Moderate agreement was found between SNAP and MP-RAGE in identification of IPH

• SNAP imaging might be a more sensitive tool to detect carotid IPHs

• Compared with the MP-RAGE sequence, SNAP imaging can detect carotid IPHs with smaller size

• SNAP imaging can help clinicians to optimise the treatment strategy