Comparison of 3D multi-echo gradient-echo and 2D T2* MR sequences for the detection of arterial thrombus in patients with acute stroke

Objectives

We compared a multi-echo gradient-echo magnetic resonance sequence (susceptibility-weighted angiography [SWAN]) with the T2* sequence for the detection of an arterial thrombus in acute ischaemic stroke.

Methods

Seventy-four consecutive patients with acute ischaemic stroke were included. Proximal arterial occlusions were diagnosed using time-of-flight (TOF) magnetic resonance angiography (MRA). Two-dimensional (2D) axial reformats from 3D SWAN were generated to match with 2D T2* images. For arterial thrombus detection, each set of MR images (T2*, 2D SWAN reformats and 3D multiplanar SWAN images) was examined independently and separately by three observers who assigned the images to one of three categories: (0) absence of thrombus, (1) uncertain thrombus, (2) certain thrombus. Agreement and diagnostic accuracy were calculated.

Results

Twenty-four proximal arterial occlusions involving the anterior (n?=?20) or posterior (n?=?4) circulation were found. Inter-observer agreement was moderate using T2* images (κ?=?0.58), good using 2D SWAN reformats (κ?=?0.83) and excellent using multiplanar SWAN images (κ?=?0.90). For the diagnosis of thrombus, T2* images were 54 % sensitive and 86 % specific, 2D SWAN reformats were 83 % sensitive and 94 % specific and SWAN multiplanar analysis was 96 % sensitive and 100 % specific.

Conclusions

Three-dimensional SWAN sequence improves the detection of arterial thrombus in patients with acute ischaemic stroke in comparison with the 2D T2* sequence.

Key Points

? Multi-echo gradient-echo MR (e.g. susceptibility-weighted angiograph, [SWAN]) is increasingly used in neuroradiology. ? Compared with conventional T2* sequences, SWAN improves detection of arterial thrombus. ? Multiplanar SWAN analysis had the best diagnostic performance for arterial thrombus detection. ? Sensitivity was 96?% and specificity 100?%. ? Findings support combination of time-of-flight and susceptibility effects in suspected acute stroke.