[Radiological diagnostics of spinal tumors. Part 2: special diagnostics of intradural tumors and tumor-like lesions]

Diffusion tensor imaging in unclear intramedullary tumor-suspected lesions allows separating tumors from inflammation

DESIGN

Prospective diagnostic study.

OBJECTIVES

Primary imaging-based diagnosis of spinal cord tumor-suspected lesions is often challenging. The identification of the definite entity is crucial for dedicated treatment and therefore reduction of morbidity. The aim of this trial was to investigate specific quantitative signal patterns to differentiate unclear intramedullary tumor-suspected lesions based on diffusion tensor imaging (DTI).

SETTING

Medical Center - University of Freiburg, Germany.

METHODS

Forty patients with an unclear tumor-suspected lesion of the spinal cord prospectively underwent DTI. Primary diagnosis was determined by histological or clinical work-up or remained indeterminate with follow-up. DTI metrics (FA/ADC) were evaluated at the central lesion area, lesion margin, edema, and normal spinal cord and compared between different diagnostic groups (ependymomas, other spinal cord tumors, inflammations).

RESULTS

Mean DTI metrics for all spinal cord tumors (n = 18) showed significantly reduced FA and increased ADC values compared to inflammatory lesions (n = 8) at the lesion margin (p < 0.001, p = 0.001) and reduced FA at the central lesion area (p < 0.001). There were no significant differences comparing the neoplastic subgroups of ependymomas (n = 10) and other spinal cord tumors (n = 8), but remaining differences for both compared to the inflammation subgroup. We found significant higher ADC (p = 0.040) and a trend to decreased FA (p = 0.081) for ependymomas compared to inflammations at the edema.

CONCLUSION

Even if distinct differentiation of ependymomas from other spinal cord neoplasms was not possible based on quantitative DTI metrics, FA and ADC were feasible to separate inflammatory lesions. This may avoid unnecessary surgery in patients with unclear intramedullary tumor-suspected lesions.

Spinal diffusion tensor tractography for differentiation of intramedullary tumor-suspected lesions

BACKGROUND AND PURPOSE

Primary MRI diagnosis of spinal intramedullary tumor-suspected lesions can be challenging and often requires spinal biopsy or resection with a substantial risk of neurological deficits. We evaluated whether Diffusion Tensor Imaging (DTI) tractography can facilitate the differential diagnosis.

MATERIALS AND METHODS

Twenty-five consecutive patients with an intramedullary tumor-suspected lesion considered for spinal surgery were studied with a Diffusion-weighted multi-shot read out segmented EPI sequence (RESOLVE). White matter tracts ("streamlines") were calculated using the FACT algorithm and visually co-registered to a T2-weighted 3D sequence. The fused images were assessed concerning spinal streamline appearance as normal, displaced or terminated. Definite diagnosis was verified by histological analysis or further clinical work-up.

RESULTS

All patients with normal appearing streamlines (n=6) showed an acute inflammatory demyelinating pathology in the further clinical work-up. In 10 patients streamline displacing lesions were found from which 5 patients underwent a surgical treatment with histologically confirmed low-grade tumors like ependymomas and pilocytic astrocytomas. In nine patients streamlines were terminated, from which 6 patients received a histology proven diagnoses with a more heterogenous spectrum (3 cases of high grade tumor, 1 case of low grade tumor with intralesional hemorrhage and 2 cases with gliosis but no tumor cells).

CONCLUSION

Using multi-shot DTI spinal tractography acute inflammatory lesions can be differentiated from other tumorous intramedullary lesions. The entity diagnosis of spinal tumors seems to be more challenging, primarily due to the variety of factors like invasivity, expansion or intralesional hemorrhage.

Geometrical dimensions and morphological study of the lumbar spinal canal in the normal Egyptian population

Information regarding the precise dimensions of the lumbar vertebrae is essential for spinal surgery and instrumentation. When stenosis of the vertebral canal or the intervertebral foramen exists, the neural structures in them can be affected and cause symptoms such as low back or radicular pain. Accurate and comprehensive spinal canal measurements in the lumbar vertebrae are incomplete. The purpose of this study was to collect data on the dimensions of the lumbar spinal canal from computed tomography scans. Three hundred patients (162 men and 138 women) were studied. Computed tomography scans were obtained to determine the normal values of the midsagittal diameter, interpedicular distance, and lateral recess depth in the normal Egyptian population. The narrowest level was L3. The range of the midsagittal diameter was 11.07 to 26.07 mm at all levels. The range of the interpedicular distance was 17.00 to 43.41 mm at all levels. In all patients at all levels, mean lateral recess depth was 6.7 mm (range, 4-14 mm). The narrowest lateral recess depth was at L5. Few patients (3.3%) had a statistically stenotic midsagittal diameter measurement. The canal shape was not uniform along the 5 lumbar vertebrae; it ranged from being circular or rounded in the upper lumbar vertebrae to triangular in the midlumbar vertebrae to trefoil in the lower lumbar vertebrae, especially at L5. Trefoil canals existed mainly in the lower lumbar vertebrae at L5, followed by L4. Data from computed tomography scans combined with accurate measurements are the basis for anatomical studies, clinical research, and the development of implants suitable for a group of patients with measurements different from the population standard.