Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

Utility of MR Bone Imaging in the Diagnosis of Pediatric Lumbar Spondylolysis: A Potential Substitute for CT (#168)

Kohei K Okuyama 1 , Yasuchika Y Aoki 2 , Yukio Y Matushita 3 , Takeshi T Toyooka 3 , Shiro S Sugiura 3 , Seiji S Ohtori 1 , Satoru S Nishikawa 3
  1. Graduate School of Medicine, Chiba University, Chuo-ku, Chiba-shi, Japan
  2. Orthopaedic Surgery, Eastern Chiba Medical Center, Togane City, Japan
  3. Orthopaedic Surgery, Nishikawa Orthopaedic Clinic, Sakura City, japan

Introduction ：The diagnosis and determination of treatment strategies for spondylolysis, a common condition in adolescents, often require essential imaging through computed tomography (CT). However, CT involves unavoidable exposure to ionizing radiation, which poses a significant concern for adolescents. The aim of this study is to investigate the potential of a new magnetic resonance imaging (MRI) technology, MR Bone Imaging, as a possible alternative to CT in addressing these concerns.

 

Patients and Methods : From June 2023 to August 2023, we conducted MR Bone Imaging and computed tomography (CT) on all spondylolytic lesions (56 sites) diagnosed by MRI in 24 patients (mean age 13.7±2.54 years). The evaluation of the fracture lines in the pars interarticularis was performed using the sagittal images of MR Bone Imaging and CT, classified into six grades according to the Oba classification in 2013: Grade 0, no findings; Grade Ia, Partial bone absorption; Grade Ib, less than 1/2 crack image; Grade Ic, 1/2 or more crack image; Grade II, complete fracture ; and Grade III, pseudoarthrosis (Fig.1). Two evaluators independently assessed the lesions, and we calculated the intra- and inter-rater agreement between MR Bone Imaging and CT results using Cohen's kappa coefficient.

 

Results : The Kappa coefficients between MR Bone Imaging and CT were 0.69 for Evaluator A and 0.74 for Evaluator B, both falling within the range of 0.61 to 0.80, considered substantial agreement. Additionally, the inter-rater agreement for MR Bone Imaging between the two evaluators was 0.80, while for CT, it was 0.77. Both were also considered substantial agreement within the range of 0.61 to 0.80.

 

Discussion : Separation syndrome is a common stress fracture observed in adolescence. Early separation syndromes are often challenging to detect on plain X-rays, and for early diagnosis, MRI is considered valuable. On the other hand, CT is the most useful for evaluating fracture lines and determining the disease stage, but repeated exposure to radiation from CT scans is a concern. In recent years, MR Bone Imaging, a new MRI technique for assessing bone structure, has been introduced. This study suggests that MR Bone Imaging can evaluate fracture lines in separation syndrome patients, and although it may not surpass CT in certain aspects at this point, it is deemed necessary and sufficient for determining treatment strategies.

 

Conclusion : In patients with adolescent lumbar spondylolysis, the new MRI technique, MR Bone Imaging, has been suggested as a potential substitute for CT. This implies a reduction in medical radiation exposure and, furthermore, could contribute to reducing medical costs.

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Fig.1 Oba classification in 2013