Loss of fine structure and edge sharpness in fast-spin-echo carotid wall imaging: Measurements and comparison with multiple-spin-echo in normal and atherosclerotic subjects

Abstract

Purpose: To test whether the k-space acquisition strategy used by fast-spin-echo (FSE) is a major source of blurring in carotid wall and plaque imaging, and investigate an alternative acquisition approach. Materials and Methods: The effect of echo train length (ETL) and T2 on the amount of blurring was studied in FSE simulations of vessel images. Edge sharpness was measured in black-blood T1W and proton density-weighted (PDW) carotid images acquired from 5 normal volunteers and 19 asymptomatic patients using both FSE and multiple-spin-echo (Multi-SE) sequences at 3 Tesla (T). Plaque images were classified and divided in group α (tissues' average T 2 ∼40-70 ms) and group β (plaque components with shorter T2). Results: Simulations predicted 26.9% reduction of vessel edge sharpness from Multi-SE to FSE images (ETL = 9, T2 = 60 ms). This agreed with in vivo measurements in normal volunteers (27.4%) and in patient group α (26.2%), while in group β the loss was higher (31.6%). Conclusion: FSE significantly reduced vessel edge sharpness along the phase-encoding direction in T1W and PDW images. Blurring was stronger in the presence of plaque components with short T2 times. This study shows a limitation of FSE and the potential of Multi-SE to improve the quality of carotid imaging. Copyright © 2011 Wiley-Liss, Inc.