Peter Schmidt, MD; Thomas E. Mayer, MD; Robert Drescher, MD, MAFrom the Department of Neuroradiology, Institute of Radiology, University HospitalJena, Jena, Germany The purpose of this study was to evaluate the normal anatomical variability of thealar ligaments in asymptomatic individuals with 3-T magnetic resonance imaging(MRI) and to compare the findings with standard 1.5-T examinations. Thirty-sixparticipants underwent 3-T and 1.5-T MRIs. Alar ligament MRI findings wereanalyzed with regard to the features detectability, signal intensity compared with muscle tissue, homogeneity, shape, spatial orientation, and symmetry.Evaluated images were coronal T2-weighted MRI with a slice thickness, 0.8 mm. KEY POINTS FROM THIS STUDY: 1) Rupture of the alar and transverse ligaments due to whiplash injury can leadto upper cervical spine instability and subsequent neurological deterioration. 2) Delineation of the alar ligaments was significantly better on 3-T images. 3) This study demonstrates that high-field 3-T MRI provides better visualizationof the alar ligaments compared with 1.5-T MRI. The higher signal-to-noise ratioallows detection of small signal changes. 4) Approximately 25% of whiplash-injured patients experience prolongedmorbidity, with little prospect of complete resolution of pain and other symptoms. 5) 24-70% of whiplash-injured patients suffer from long-term symptoms. 6) Up to 16% [of whiplash-injured patients] remain severely impaired manyyears after the accident, which interferes with their activities of daily living. 7) The alar ligaments are considered an important ligamentous craniocervicalstructure for the integrity and stability of the craniocervical junction. Due to the lackof a disk and the horizontal nature of the facet joints, the stability of theatlantoaxial joint depends mainly on ligaments and muscles. 8) The most important function of the alar ligaments is the limitation of axialrotation, and they are most vulnerable when the head is rotated and flexed. 9) Magnetic resonance imaging (MRI) is the modality of choice to visualizeanatomy and pathology of the alar ligaments because of its high tissue contrast andmultiplanar imaging capability. 10) 9.7% of the alar ligaments were difficult to detect on 3-T MRI compared with55.6% on 1.5-T MRI. 11) This study demonstrates that reliable assessment of alar ligaments by meansof MRI can be achieved and that high-field 3-T MRI provides better visualization ofthe alar ligaments compared with 1.5-T MRI. 12) A 2009 study reported that high signal changes of the alar and transverseligaments are common in whiplash-associated disorders and unlikely to representage-dependent degeneration. 13) These authors note that the studies that claim there is no significance to alarligament signal abnormality and chronic whiplash symptoms were performed on a1.5-T MRI. They suggest that the findings and conclusion would most likely bedifferent had the authors used a 3.0-T MRI unit. 14) Alar ligament imaging is difficult because of their subtle structures andvariable orientation. T2 contrast is helpful to differentiate the ligamentousstructures of the spine from surrounding fatty tissue and muscles, as well as fromcerebrospinal fluid. 15) The higher signal-to-noise ratio of 3-T MRI compared with 1.5-T MRI allowsfor the detection of small signal changes of a ligament, which at 1.5 T will likely notovercome the noise threshold. [Key Point] 16) High-field 3-T MRI is a valuable diagnostic tool for imaging of the alarligaments because of its excellent delineation of these ligaments compared withstandard 1.5-T MRI. 17) High-field 3-T MRI increases the reliability and accuracy of alar ligamentlesion classification. COMMENTS FROM DAN MURPHY: Alar ligament integrity is of critical importance to both upper cervical chiropractorsand to chiropractors managing whiplash injuries. A number of studies we havereviewed indicate that: 1) Alar ligaments are specifically injured in motor vehicle collisions. 2) Injured alar ligaments are primarily responsible for chronic whiplashsymptoms, especially post-traumatic headaches. This study clearly points out that 3.0-T MRI has more diagnostic accuracy than dothe standard 1.5-T MRI units.