Mineralization in calcified plaque is like that of cortical bone—Further evidence from ultrashort echo time (UTE) magnetic resonance imaging of carotid plaque calcification and cortical bone

Authors


Abstract

Purpose:

This study aims to investigate carotid plaque calcification (CPC) using two-dimensional (2D) and 3D ultrashort echo time (UTE) magnetic resonance imaging (MRI) sequences and compare T1, T2*, water concentration, and bone mineral density (BMD) of CPC with those of cortical bone.

Methods:

Twelve carotid plaque specimens and eight tibial cortical bone samples were imaged with UTE sequences. Adiabatic inversion recovery prepared UTE (IR-UTE) acquisitions were used for T2* measurement. Saturation recovery prepared UTE acquisitions were used for T1 measurement. Water concentration was measured by comparing signal from CPC and bone with that from a phantom. BMD was measured withμ CT. Conventional gradient echo and fast spin echo images were also acquired for comparison.

Results:

Our studies show that CPC and cortical bone have similar T1 and BMD values but different T2* and water concentration. For CPC T2*s ranged from 0.31 to 3.87 ms, T1s ranged from 114 to 332 ms, water concentrations ranged from 6.4% to 17.6%, and BMD ranged from 977 to 1319 mg/ml. For cortical bone T2*s ranged from 0.33 to 0.45 ms, T1s ranged from 198 to 254 ms, water concentrations ranged from 24.7% to 33.8%, and mineral densities ranged from 970 to 1287 mg/ml. On average CPC shows about 5% longer T1, 5% lower BMD, 440% longer T2*, and 130% lower water concentration when compared to human cortical bone.

Conclusions:

CPC bears remarkable similarities with cortical bone in terms of BMD and T1. CPC shows a higher mean T2* and a lower mean water concentration.

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