Diagnostic accuracy of MRI in detecting posterior ligamentous complex injury in thoracolumbar vertebral fractures

Transcription

1 Diagnostic accuracy of MRI in detecting posterior ligamentous complex injury in thoracolumbar vertebral fractures Poster No.: C-1726 Congress: ECR 2011 Type: Scientific Exhibit Authors: E. Aguirre, P. Chimeno, E. Benza, J. Pizones, B. Lannegrand; Madrid/ES Keywords: Trauma, MR, Musculoskeletal spine, Emergency DOI: /ecr2011/C-1726 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 17

2 Purpose Spinal instability is defined by White and Panjabi as the loss of the spine's ability to keep its patterns of displacement under physiologic loads without neurological deficit, without provoking major deformity nor pain [1]. Thus determining spinal stability is substantial in the selection of therapeutic options in acute thoracolumbar spinal fractures. The spinal stabilizing system is mainly determined by two components: spinal column and posterior ligamentous complex (PLC) with spinal muscles [2]. The structures of PLC contribute significantly to the stability of the thoracolumbar spine, it includes the supraspinous ligament (SSL), ligament interspinous (ISL), ligamentum flavum (LF) and facet joint capsules (FC). Among the different imaging techniques used in the assessment of acute thoracolumbar injuries, Magnetic Resonance Imaging (MRI) may be less used due to its high cost and limited availability, however it is superior to radiography (RX) and computed tomography (CT) in the evaluation of CLP. Purpose The aim of this prospective study is to assess the diagnostic accuracy of MRI in the assessment of the integrity of CLP compared with surgical findings. Methods and Materials Patients Twenty-eight patients with acute thoracolumbar fracture were prospectively studied during The exclusion criteria were pathologic fractures such are the ones due to neoplasic process, osteopenia (female patients over 55 years-old and male patients older than 60 years) or neuromuscular pathology. Page 2 of 17

3 Imaging protocol The patients were examined by plain radiography and MRI before surgery, within 1 week from injury. MRI examination was performed using 1.5 T magnet T1 and T2 Fat sat and T2 STIR weighted acquisitions (FOV 350 mm, matrix 320 x 384, distance factor 10%). Thoracolumbar fractures were classified according to new Thoracolumbar Injury Classification and Severity Score (TLICS) proposed by Vaccaro et al [4], that distinguises 4 basic types of fracture based on logical forces that affect the spine (compression, flexion-distraction and rotation-traslation). Fig.: Morphology of fratures based on the Thoracolumbar Injury Classification and Severity Score (TLICS) by Vaccaro et al. References: E. Aguirre; Radiology, Hospital Universitario Getafe, Madrid, SPAIN A musculoskeletal radiologist evaluated integrity of each component of posterior ligament complex (PLC). Patterns of abnormality seen on MRI for ligamentous structures were edema (high T2 signal), disruption ("black stripe" on T1 sagittal MRI) and high T2 signal, widening or dislocation of facet capsules [5,6]. Page 3 of 17

4 MRI - Surgery correlation Preoperative MR imaging findings were compared with intraoperative direct observation of PLC injury (gold standard). PLC components were characterized as intact or injured by MR imaging and intraoperative observation. Sensitivity, specificity, positive predictive value and negative predictive value of MRI were determined for detecting PLC injury. Images for this section: Fig. 1: Morphology of fratures based on the Thoracolumbar Injury Classification and Severity Score (TLICS) by Vaccaro et al. Page 4 of 17

5 Results Twenty-eight patients attended hospital sustaining acute thoracolumbar vertebral fracture during The patients were 14 women and 14 men, (mean age, 41 years; range, 10-60). Causes of trauma were automobile accidents (n= 11), falls from a height (n= 6) and other (n= 11). Forty-seven fractures were detected on conventional radiography. Most of patients (75% 21/28) had unique fracture. The most common fracture level was the thoracolumbar junction (T11-L2: 53% 25/47). Our study depicted 27 compressions, 13 burst, 7 flexion- distraction and 1 rotation. There were 2 patients who sustained incomplete spinal cord lesion. Thirteen patients underwent surgery, in 11 patients posterior approach was performed and 2 underwent both anterior and posterior fusion. PLC MRI evaluation PLC was evaluated in 72 levels on MRI. The findings were correlated with surgery in 26 levels (of 13 patients). PLC injury was detected in 19/26 (73%), it was more common in flexion-distraction and rotation fractures. Most frequently affected ligament was ISL (17/26, 65,4%), followed by SSL (12/26, 46,2%) and FC (12/26, 46,2%). Ligamentum flavum was the least injured (7/26, 26,9%) Fig 1-8. MRI-Surgery correlation Page 5 of 17

6 MR imaging was highly sensitive for injury to facet capsules (100%) and interspinous ligament (94%), but it was less sensitive for injury to supraspinous ligament (83,3%) and ligamentum flavum (85,7%). See Table 1 Table 1 S E PPV NPV 83, ,5 Interspinous 94 Ligament (ISL) ,5 Ligamentum Flavum (LF) 85, Facet Capsules (FC) ,7 85,7 100 Supraspinous Ligament (SSL) Images for this section: Fig. 1: A flexion distraction fracture in 28 year-old patient. Sagittal T2 fat sat and T1 weighted images depict hyperintensity and disrupted supraspinous ligament at D10 (white arrows). Page 6 of 17

7 Fig. 2: Sagittal T2 STIR image shows a flexion-distraction fracture with bulging vertebral posterior wall and high T2 signal of interspinous ligament and paravertebral tissues (blue arrow). Page 7 of 17

8 Fig. 3: Sagittal T2 STIR weighted image demonstrates fracture hyperintensity of interspinous ligament (blue arrow) and disrupted supraspinous (red arrow) in a 38 yearold patient who suffered flexion distraction fracture. Page 8 of 17

9 Fig. 4: On the sagittal STIR weighted MRI image ligamentum flavum is disrupted (red arrow) and extradural hematoma is occupying spinal channel. Page 9 of 17

10 Fig. 5: Axial T2 STIR weighted image shows hypersintense facet capsule joints (red arrows) due to distension and paravertebral tissue edema. Page 10 of 17

11 Fig. 6: On axial T2 Fat sat weighted image there is distension of facet capsule joints (white arrows) and fracture of left lamina (red arrow) Page 11 of 17

12 Fig. 7: Axial T1 and T2 Fat sat weighted images show disruption of left facet capsule joint and lamina in a rotation fracture (blue arrow). Page 12 of 17

13 Fig. 8: A 10 year-old patient who sustained D11 and D12 flexion-distraction fracture. On the sagittal STIR weighted MRI image (A), the supraspinous (white arrow), interspinous (orange arrows) ligaments are hyperintense and shows disrupted ligamentum flavum (red arrow) and extradural hematoma occupying spinal channel. On the sagittal STIR weighted MRI image (B) left and right facet capsules are dislocated (green arrow). On the axial Fat Sat T2 weighted MRI image (C) ligamentum flavum (red arrow) is disrupted and there is occupation of spinal channel by extradural hematoma. Page 13 of 17

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15 Fig. 9: Intraoperative findings show disrupted interspinous ligament (blue arrow) and desinserted supraspinous ligament (green arrow). Page 15 of 17

16 Conclusion 1. MR imaging is highly sensitive for detection PLC injury, specially to facet capsules and interspinous ligament in acute thoracolumbar vertebral fractures. 2. MRI is highly specific for detecting intact supraspinous ligament and ligamentum flavum. 3. Therefore MRI is a useful technique with high diagnostic accuracy for detecting PLC injuries, thus essential for detecting unstable fractures that may benifit of surgical treatment. References [1] A.A. White, M.M. Panjabi (Eds.), Clinical biomechanics of the spine, 2nd ed, JB Lippincott, Philadelphia, PA, [2] Panjabi MM. Clinical spinal instability and low back pain. J.Electromyogr.Kinesiol Aug;13(4): [3] Valentini MC, Busch R, Ferraris MM, Venturi F. The role of imaging in the choice of correct treatment of unstable thoraco-lumbar fractures. Eur J Radiol ;59(3): [4] Vaccaro AR, Lehman RA,Jr, Hurlbert RJ, Anderson PA, Harris M, Hedlund R, et al. A new classification of thoracolumbar injuries: the importance of injury morphology, the integrity of the posterior ligamentous complex, and neurologic status. Spine (Phila Pa 1976) 2005 Oct 15;30(20): [5] Oner FC, van Gils AP, Dhert WJ, Verbout AJ. MRI findings of thoracolumbar spine fractures: a categorisation based on MRI examinations of 100 fractures. Skeletal Radiol 1999 Aug;28(8): Page 16 of 17

17 [6] Vaccaro AR, Lee JY, Schweitzer KM,Jr, Lim MR, Baron EM, Oner FC, et al. Assessment of injury to the posterior ligamentous complex in thoracolumbar spine trauma. Spine J Sep-Oct;6(5): Personal Information Page 17 of 17