A new MRI technique for imaging scoliosis in the sagittal plane

Abstract

IntroductionIn idiopathic scoliosis, biomechanical, biological and clinical views confirm that the deformity in the sagittal plane is of primary pathogenetic significance [8]. A fixed lordotic section causes rotation and increased lateral curvature of the spine as a result of the asymmetry in the coronal plane [2]. Various studies confirm that lordosis of the thoracic vertebrae is characteristic for idiopathic scoliosis in adolescents [3,8,11].The scoliotic deformity in the follow-up of scoliosis patients is usually examined using anteroposterior (AP) radiographs. An additional lateral radiograph, while providing additional information, would result in increased X-ray exposure. On the lateral X-ray projection, the mean entrance surface radiation dose for the thoracic spine is 6.1 mGy and for the lumbar spine 6.7 mGy [1]. However, monitoring the scoliotic deformity on a lateral view can provide additional information, useful, for example, for assessing the effect of brace treatment in two planes or determining further prognostic factors.The technique of MR total spine imaging developed by the authors allows visualization of the whole spine in the coronal and sagittal planes [4,5]. The present study aimed to establish whether MR total spine imaging is a reliable and useful method to image scoliosis in the sagittal plane. AbstractThe purpose of the present study was to introduce a new magnetic resonance imaging (MRI) procedure showing the whole spine in a coronal and sagittal plane, and to study the assessment of sagittal Cobb angle measurements using this technique. Prospectively we studied 32 patients (average age 14.8 years) with idiopathic scoliosis (mean thoracic Cobb angle 33°on radiograph) and 18 patients (average age 14.5 years) without scoliosis. The MRI investigation was carried out in a standard supine position. The cervical and upper thoracic spine and the lower thoracic and lumbar spine were measured on a 1.5-T Gyroscan ACS-NT Powertrak 6000 system. An algorithm was developed to combine the results of the cranial and caudal scans into a coronal and a sagittal image of the whole spine (MR total spine imaging). Measurement of the sagittal Cobb angle conducted ten times by four independent investigators revealed an intraobserver variance of 1.6°and an interobserver variance of 1.8°. In the group with scoliosis the mean sagittal Cobb angle from T4 to T12 was 12°(range -3°to 24°) and in the group without scoliosis 22°(range 16°to 30°), which was a significant difference. MR total spine imaging makes it possible to image scoliosis in the sagittal plane. On these MR projections, idiopathic thoracic scoliosis was identified by a reduced sagittal Cobb angle. MR total spine imaging would allow monitoring of scoliosis in the sagittal plane, which can reveal relevant clinical data without radiation exposure.

Sagittal Plane Analysis of the Spine and Pelvis in Adolescent Idiopathic Scoliosis According to the Coronal Curve Type

“…28 Many authors have already demonstrated that the TK is smaller for thoracic curves than for control curves. 11,14,29,30 The small TK is related to the disturbed growth of the vertebral body in thoracic AIS. 14 In contrast, Propst-Proctor and Bleck 12 found no significant difference in the TK between patients with scoliosis and control subjects.…”

Ultrasound Imaging of Spinal Vertebrae to Study Scoliosis

“…Therefore, alternative non-invasive, radiationfree, and reliable methods to study scoliosis are urgently sought. Magnetic resonance imaging (MRI) could reconstruct high-quality tomographic images of spinal vertebrae [17,18]. However, the use of MRI is costly and time consuming; therefore, its use to evaluate AIS still remains very limited.…”

Visualisation of the brace effect on the spinal profile in idiopathic scoliosis

“…the presence of a syrinx or other intraspinal pathologies [2,4]. The department of radiology at the University of Bonn developed the MR total spine imaging to reduce the radiation exposure in the follow-up of scoliosis patients [5,10]. A further reconstruction algorithm allows visualising the whole spine in vertical projections with rotational steps of 2°, from )90°to 90°, referred to as MR animation.…”