Measurement of vertebral endplate bone marrow lesion (Modic change) composition with water-fat MRI and relationship to patient-reported outcome measures
Supplementary material (online only)
Detailed methods Imaging
MRI was performed on a Discovery MR 750 3T scanner (GE Healthcare, Waukesha, WI). Clinical fast spin echo images with T1 and T2 weighting were acquired in the sagittal orientation with a field-of-view of 26 cm and slice thickness of 4 mm. Fat-saturated T2-weighted images had an echo time (TE) = 60 msec, repetition time (TR) = 4877 msec, echo train length (ETL) = 24, readout-bandwidth (rBW) = ±50 kHz, and an in-plane resolution of 0.6 mm. T1-weighted images had TE = 15 msec, TR = 511 msec, ETL
= 4, BW = ±50 kHz, and an in-plane resolution of 0.5 mm. Endplate BML grading was done on the T1- and fat-saturated T2-weighted images according to standard MC definitions, which classify type I
“fibrovascular” BML (MC 1) as hypointense/hyperintense on T1/T2, type II “fatty” BML (MC 2) as hyperintense/iso-to-hypointense on T1/T2, and type III “sclerotic” BML (MC 3) as
hypointense/hypointense on T1/T2.
Water-fat imaging consisted of a 3D spoiled gradient recalled (SPGR) sequence with six echoes and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) reconstruction algorithm. Images were acquired in the sagittal orientation with a field-of-view of 22 cm x 22 cm and slice thickness of 4 mm. Imaging parameters included: TR = 6.6 msec, TE/TE=2.1/1.0 msec, rBW=±83.3 kHz, flip angle 3, and in-plane resolution of 0.86 mm. Acquisition times were ~3-5 minutes.
