MRI of Dumbbell-Shaped Spinal Tumors

The purpose of our study is to review the clinical features and MR findings in patients with dumbbell-shaped spinal tumors that affect the intervertebral foramen.Two radiologists retrospectively evaluated a total of 19 tumors from the period 1989-1994 that exhibited dumbbell configuration. These included 11 benign tumors, including 9 neurogenic ones, and 8 malignant tumors.The time between onset of symptoms and admission was shorter in patients with malignant tumors (mean 3.9 months) than in patients with benign tumors (mean 41.1 months). There was a statistically significant difference (p < 0.05) in the short/long axis ratios (minimum tumor diameter divided by maximum tumor diameter) in the vertebral canal components between benign and malignant tumors. All malignant tumors in this study were extradural and paraspinal type (p < 0.05). Most benign tumors had regular margins and enlarged intervertebral foramina, while most malignant ones had irregular margins (p < 0.05). Many neurogenic tumors had regular margins and enlarged intervertebral foramina, while most malignant ones had irregular margins (p < 0.05> Many neurogenic tumors had cystic lesions (77.8%) and a string-of-beads structure (44.4%). Those tumors that surrounded the thecal sac in the vertebral canal and whose adjacent vertebral bodies had abnormal signal intensities were infiltrating and malignant.There are many kinds of dumbbell-shaped spinal tumors other than neurogenic ones. MRI is useful in diagnosing dumbbell-shaped spinal tumors, especially those of neurogenic origin, and aids in distinguishing benign from malignant tumors.