Temporal evolution of the signal intensity of hyper-acute ischemic lesions in a canine stroke model: influence of hyperintense acute reperfusion marker.

BACKGROUND: To assess the influence of the hyperintense acute reperfusion marker (HARM) on the relative signal intensity (rSI) and apparent diffusion coefficient (ADC) of hyper-acute ischemic lesions in a canine stroke model.

METHODS: Middle cerebral artery occlusion models were established using autologous clot embolization. Diffusion-weighted (DW) and fluid-attenuated inversion recovery (FLAIR) imaging was performed at 1, 2, 3, 4.5 and 6 h after embolization. HARM was defined as the delayed enhancement of cerebrospinal fluid on the subsequent FLAIR images after contrast media used.

RESULTS: Twenty-four stroke models were successfully established and divided into the HARM (n = 16) and No-HARM group (n = 8). No significant differences were found in the rSI on DWI (b0 and b1000 map) and relative ADC between the two groups at each time point after embolization (all P > 0.05). There were no significant differences in the rSI on FLAIR at 1 and 2 h after embolization between the two groups (P > 0.05), while the HARM group showed significantly higher rSI on FLAIR than the No-HARM group at 3, 4.5 and 6 h after embolization (P = 0.044, 0.036 and 0.001, respectively).

CONCLUSIONS: HARM should be noted during the quantitative analysis of FLAIR images in future clinical practice.