Improved Lesion Detection by Using Axial T2-Weighted MRI with Full Spinal Cord Coverage in Multiple Sclerosis

BACKGROUND AND PURPOSE:Identification of lesions in specific locations gains importance in multiple sclerosis imaging diagnostic criteria. In clinical routine, axial scans are usually exclusively obtained to depict the cervical spinal cord or used to confirm suspected lesions on sagittal scans. We sought to evaluate the detection rate for MS lesions on axial T2WI scans with full spinal cord coverage in comparison with sagittal scans.MATERIALS AND METHODS:One hundred fifteen patients with definite or suspected MS underwent an MR imaging examination including 3-mm sagittal and 3.5-mm axial T2-weighted images with full spinal cord coverage. T2WI lesions were identified on axial and sagittal scans independently by 2 raters. Axial diameter, craniocaudal extension, lesion intensity, and location were analyzed.RESULTS:Four hundred forty-nine of 509 (88.2%) lesions were detected on axial and 337/509 (66.2%) on sagittal scans. Only 277/449 (61.7%) axial lesions were also detected on sagittal images. The number of lesions visible on sagittal and axial images was dependent on the axial lesion diameter (P < .001).CONCLUSIONS:Axial T2WI scans with full spinal cord coverage showed 22% more lesions in patients with MS in comparison with sagittal scans, especially for lesions with small axial diameters. We suggest including biplanar spinal MR imaging with full spinal cord coverage for lesion detection in MS in clinical routine and for clinical studies.

Multiple sclerosis is a chronic inflammatory disease, considered the most common demyelinating process involving the central nervous system.¹ The diagnosis requires typical clinical findings in addition to the evidence of lesions in the CNS disseminated in time and space seen on MR imaging of the brain or spinal cord.² While the diagnostic focus of most multiple sclerosis studies is still based on MR imaging of the brain, several studies have revealed spinal cord lesions in 75%–90% of patients with clinically diagnosed MS.^3–6 As many as 20% of spinal MS lesions are isolated, without coexisting brain lesions.¹Spinal cord abnormalities seen on MR imaging were incorporated into the McDonald Diagnostic Criteria for MS in 2005.^7,8 Since the revision of the McDonald Diagnostic Criteria for MS in 2010,⁹ they have gained even more importance because better spinal cord lesion detection potentially impacts the recognition of the dissemination of MS lesions in space.In 2006, a consortium of MS centers published consensus guidelines with a standardized MR imaging protocol for spinal cord imaging in MS, recommending a 3-plane scout; a pre- and post-contrast-enhanced sagittal T1; a pre-contrast-enhanced sagittal FSE proton-density/T2; and additionally, only in case of suspected lesions, a pre-contrast-enhanced axial FSE proton-density/T2 and a post-contrast-enhanced axial T1.¹⁰ In the clinical routine of MS diagnostics, axial scans are typically obtained exclusively with coverage of the cervical spinal cord or are used to confirm suspected lesions in sagittal scans. This is mainly due to the long scanning time of axial scans with full spinal cord coverage.So far in most MS studies, spinal cord lesions were evaluated and marked on the sagittal plane,^11,12 while some groups included axial scans covering only the cervical spine^13–15 and very few studies analyzed the axial and sagittal planes of the entire spinal cord.^3,16 Also, lesion location and size were described on sagittal scans only or on axial scans covering the cervical spinal cord exclusively.¹⁵We hypothesized that axial T2WI scans with full spinal cord coverage would detect more T2WI lesions in comparison with sagittal scans. We sought to evaluate detection rates for T2WI lesions on axial and sagittal scans in relation to the distribution and extent of spinal cord lesions in patients with MS. To our knowledge, this is the first study focusing on the clinical application of axial 3.5-mm scans with full spinal cord coverage. We used a sequence with reasonable duration, feasible in clinical routine.