Incidental Findings of the Lumbar Spine at MRI During Herniated Intervertebral Disk Disease Evaluation

OBJECTIVE. The objective of our study was to evaluate the frequency and types of incidental findings of the lumbar spine during MR evaluation for herniated intervertebral disk disease. MATERIALS AND METHODS. A total of 1268 patients (male-to-female ratio, 421: 847; age range, 1-97 years) with clinically suspected herniated intervertebral disk disease underwent MRI of the lumbar spine. Musculoskeletal radiologists evaluated the MR examinations for the presence of incidental findings. We defined incidental finding as any abnormal finding not related to the chief complaint. Vertebral hemangioma, Tarlov cyst, fibrolipoma, synovial cyst, and sacral meningocele were included. Frequency distributions of the assessed imaging characteristics were calculated. For analysis of the relationship of incidental findings with patient characteristics, the chi-square test was used. RESULTS. Overall, 107 patients (8.4%) had incidental findings. Fibrolipoma was most common (41 cases, 3.2%), followed by Tarlov cyst (27 cases, 2.1%) and vertebral hemangioma (19 cases, 1.5%). Fibrolipoma and sacral meningocele were more common in males (p < 0.05). There was no difference in the incidence between the sexes in the other incidental findings (p = 0.26-0.96). Four of the five incidental findings were significantly more frequent in individuals younger than 50 years (p < 0.05), whereas the incidence of vertebral hemangioma did not differ by patient age (p = 0.32). CONCLUSION. Incidental findings at MRI of the lumbar spine were common and associated with age and sex. Most were benign findings. An awareness of the prevalence of the incidental findings detected at MRI of the lumbar spine is helpful for diagnosing lesions not related to symptoms.