Wednesday, May 23, 2012

MRI Scanning Technique of Thoracic spine

Initially a localizer is taken in three planes.

Then the myelogram is planned in localizer in sagittal and coronal plane. The epicenter of FOV is kept at the posterior border of sixth thoracic vertebra in sagittal localizer and the scan line is kept at the middle of the vertebrae in coronal localizer. In axial localizer, the mid point of the scan line is kept at the posterior border of the vertebra where the line divides the vertebra into right and left equal halves.
T2 sagittal images are obtained. The mid scan line is run through the middle of the spinal cord as seen in myelogram and the parasagittal images are obtained so that the right and left nerve root foramina can be depicted. The scan lines run perpendicular to the vertebra in axial localizer and the epicenter of FOV is kept at the posterior border of sixth thoracic vertebra in sagittal localizer so that the FOV covers from seventh cervical vertebra upto inferior border of first lumbar vertebra. Labelling of the vertebra may be required for relevance.
T1 sagittal images are obtained by copying the scan lines of the T2 sagittal sequence.
T2 STIR sagittal images are also obtained by copying the scan lines of the T2 sagittal sequence.
T2 Axial sequence is planned now. This sequence is planned in mid- T2 sagittal image. The stacks of slices are centered at the intervertebral discs covering the superior and inferior end plates. 1-3 slices are planned in each intervertebral discs from seventh cervical vertebra to first lumbar vertebra. Less slices are chosen where disc bulging and protusion are not seen and more slices are required where there is disc bulging and protusion.
T1 Axial sequence is planned by copying the slice lines of T2 Axial sequence.
T2 Coronal sequence may also be required. The mid scan line is made parallel to the anterior aspect of spinal cord in myelogram and make sure that the whole thoracic spinal cord is included in the scan plan.
The routine MRI sequences for Thoracic spine are:
T1 Sagittal
T2 Sagittal STIR
T2 Axial
T1 Axial
T2 Coronal (optional)
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