MR imaging of calcified herniated thoracic disk

Diffuse vertebral body edema due to calcified intraspongious disk herniation

We describe the case of a patient with a recent history of high back pain, with magnetic resonance imaging (MRI) of the thoracic spine showing intervertebral disk herniation into the spongious bone of the vertebral body of T9 that might have caused diffuse, low signal intensity on fluid-attenuated inversion recovery T1-weighted (FLAIR-T1W) images, high signal intensity magnetic resonance (MR) on T2-weighted (T2W) images and T2-weighted fat-suppressed images (T2W-FSIs) and marked enhancement on the vertebral body of T9 with gadolinium on T1-weighted fat-suppressed images (T1W-FSIs) images. Those findings suggested diffuse edema and might be indistinguishable from tumoral or inflammatory diseases, but the plain films and the reformatted sagittal computed tomography scans of the thoracic spine were helpful to show a calcified part of the intervertebral disk migrating into the vertebral body of T9. The patient made full recovery from the symptoms after conservative treatment and at the follow-up MRI showed normalization of the bone marrow signal intensity of the vertebral body of T9.

Foraminal deposition of calcium pyrophosphate dihydrate crystals in the thoracic spine: possible relationship with disc herniation and implications for surgical planning

✓ The authors report two cases of nodular calcium pyrophosphate dihydrate (CPPD) crystal deposition close to the thoracic neural foramen, which caused chronic radiculopathy. Preoperatively, the lesions were interpreted as calcified disc herniations. Both patients underwent surgery in which an extended transfacet pedicle-sparing approach was used. Incision of the posterior longitudinal ligament released soft degenerated material. In both cases, histological examination showed abundant degenerative debris along with CPPD crystals.

Spinal CPPD deposition is a comparatively rare disease that almost invariably involves the posterior aspect of the spinal canal, typically the ligamentum flavum. The exceptional foraminal location of the lesions reported here, combined with the surgical findings, indicated that the CPPD crystals were deposited on a laterally herniated disc fragment. A distinctive feature in both cases was the soft consistency of the resected tissue. The consistency of the disc material and the location of the lesion in the axial plane (that is, median compared with lateral) are key factors in determining the optimal surgical approach to thoracic disc herniations. In describing consistency, terms such as “calcified” and “hard” have been used interchangeably in the literature. In the cases reported here, what appeared on computerized tomography and magnetic resonance imaging studies to be densely calcified lesions were shown intraoperatively to be soft herniations.

The authors' experience underscores that not all densely calcified herniated discs are hard. Although detection of this discrepancy would have left surgical planning for the lateral disc herniations unchanged, it could have altered planning for centrally or centrolaterally located disc herniations.

Gd-DTPA-enhanced MR in thoracic disc herniations

The Gd-DTPA-enhanced magnetic resonance findings in two patients with herniated thoracic intervertebral discs are reported. The first patient was a 56-year-old woman with a small subligamentous T6-7 disc herniation, slightly lateralized to the right. The second patient was a 51-year-old man with a central and right posterolateral disc herniation, including a large calcified fragment, at the T8-9 level. The nonenhanced MR examination revealed the presence of an extradural mass lesion in both patients, impinging upon the dural sac and compressing and displacing the spinal cord posteriorly. The lesion was slightly hypointense on both T1- and T2-weighted spin echo sequences. Following intravenous injection of Gd-DTPA in a dosage of 0.1 mmol/kg body weight, enhancement of the posterior longitudinal ligament was noted and triangular areas of contrast uptake were seen to occur in the epidural space above and below the herniated disc. At surgery, they were found to correspond to dilated and congested epidural veins.