Purpose: The insidious onset and variety of clinical symptoms of cervical myelopathy (CM) pose a big challenge to clinician for early diagnosis and precise prognostication. The gross morphological and signal changes in T2-weighted magnetic resonance images (MRI) did not necessarily correlate with the severity of chronic compressive injuries of spinal cord. In the present study, we aimed to employ a relatively novel index in diffusion MR imaging directional entropy (DE) to investigate the potential pathogenic levels in CM patients.
Methods: Subjects Total 22 volunteers were recruited in this study with informed consent, including 8 CM patients (64±20yrs) and 14 healthy subjects (46±16yrs). Diffusion MRI maging MR imaging were performed with a 3T MR system (Philips, Netherlands), by using pulsed gradient, spin-echo-echo-planar imaging sequence (data acquisition parameters: TR/TS=5000/60ms; 13 slices (7mm slice thickness, 2.2mm gap); field of view= 80 (RL) ×36 (AP) mm; matrix size=128×128; non-collinear diffusion encoding directions=16, b=600s/mm2; reconstruction resolution= 0.63×0.63×7.0mm3).
Results: It was revealed the DE value in the myelopathy cord was significantly higher than healthy cord (p<0.05) at compression level (DE(0): 0.91±0.03) and adjacent three levels towards both rostral (DE(-3): 0.74±0.05; DE(-2): 0.82±0.05; DE(-1): 0.85±0.03) and caudal directions(DE(1):0.83±0.05; DE(2): 0.81±0.06; DE(3): 0.79±0.05). The pathogenic probability was estimated in a multilevel case by extracted increment (C3~4: 31.6%; C4~5: 5.3%; C5~6: 40.5%; C6~7:22.6%).
Conclusion: The directional entropy successfully described and quantitatively measured the microstructural disorganization in the cervical myelopathy. It might be a novel approach for the pathogenic level estimation.