Sagittal/coronal SE/FSE T1 or coherent GRE T2*

Acts as a localizer if three-plane localization is unavailable. The coronal or sagittal planes may be used.

Coronal localizer: Medium slices/gaps are prescribed relative to the vertical alignment light, from the posterior aspect of the spinous processes to the anterior border of the vertebral bodies. The area from the base of the skull to the second thoracic vertebra is included in the image.

P 20 mm to A 30 mm

Sagittal localizer: Medium slice thickness/gaps are prescribed on either side of the longitudinal alignment light, from the left to the right lateral borders of the vertebral bodies. The area from the base of the skull to the second thoracic vertebra is included in the image.

L 7 mm to R 7 mm

Sagittal SE/FSE T1 (Figure 9.3)

Thin slices/gaps are prescribed on either side of the longitudinal alignment light, from the left to the right lateral borders of the vertebral bodies (unless the paravertebral areas are required). The area from the base of the skull to the second thoracic vertebra is included in the image.

L 22 mm to R 22 mm

Sagittal SE/FSE T2 or coherent GRE T2* (Figure 9.4)

Slice prescription as for sagittal T1.

Axial/oblique SE/FSE T1/T2 or coherent GRE T2* (Figure 9.5)

Thin slices/gaps are angled so that they are parallel to the disc space or perpendicular to the lesion under examination (Figures 9.6 and 9.7). For disc disease, three or four slices per level usually suffice. For larger lesions such as tumour or syrinx, thicker slices covering the lesion and a small area above and below may be necessary.

Sagittal/axial oblique SE/FSE T1

Slice prescription as for axial/oblique T2* with contrast enhancement for tumours.

Technical issues

The SNR in this region is mainly dependent on the quality of the coil. Posterior neck coils give adequate signal for the cervical spine and cord, but signal usually falls off at the anterior part of the neck, so they are not recommended for imaging structures such as the thyroid or larynx. In addition, flare from the posterior skin surface can be troublesome in sagittal T1 imaging, where the large fat pad situated at the back of the neck returns a high signal. Volume coils produce even distribution of signal, but the SNR in the cord is sometimes reduced compared with a posterior neck coil. Multi-coil array combinations commonly produce optimum SNR, and may be used with a large FOV to include the thoracic spine. This strategy is important when pathology extends from the cervical to the thoracic areas of the cord, for example, syrinx.

Spatial resolution is also important, especially in axial/oblique imaging, as the nerve roots in the cervical region are notoriously difficult to visualize. Thin slices with a small gap and relatively fine matrices are employed to maintain spatial resolution. Ideally, 3D imaging is used as this allow very thin slices with no gap, and the volume may be viewed in any plane (see Volume imaging in Parameters and trade-offs in Part 1). Multiple NEX/NSA are also advisable if the inherent SNR is poor. Therefore, unless FSE is utilized, scan times are often of several minutes duration.

Fortunately, a rectangular/asymmetric FOV is used very effectively in sagittal imaging as the cervical spine fits into a rectangle with its longitudinal axis running S to I. This facilitates the acquisition of fine matrices in short scan times. With a reduced FOV in the phase direction, aliasing may be a problem. In sagittal imaging, this artefact originates from the chin and the back of the head wrapping into the FOV. Increasing the size of the overall FOV or utilizing oversampling (if available) may eliminate or reduce this artefact. In addition, spatial pre-saturation pulses brought into the FOV to nullify signal coming from these structures are effective (see Flow phenomena and artefacts in Part 1).

The multiple 180° RF pulses used in FSE sequences cause lengthening of the T2 decay time of fat so that the signal intensity of fat on T2-weighted FSE images is higher than in CSE. This sometimes makes the detection of marrow abnormalities difficult. Therefore, when imaging the vertebral bodies for metastatic disease, a STIR sequence should be utilized (see Pulse sequences in Part 1).

Artefact problems

The cervical area is often plagued with artefact. Not only does aliasing from structures outside the FOV obscure the image, but the periodic, pulsatile, motion of CSF within the spinal canal produces phase ghosting. The speed of flow is usually quite rapid in the cervical region, and therefore, conventional flow-reducing measures, such as spatial pre-saturation and GMN, are less effective than in the lumbar region where CSF flow is slower. On T1-weighted images, spatial pre-saturation pulses placed S and I to the FOV are usually sufficient. However, on T2-weighted sequences, flow artefact is commonly troublesome. In addition, selecting an S–I phase direction along with oversampling can also reduce CSF flow artefact in sagittal imaging and in that scenario, spatial pre-saturation pulses are not needed.

Related posts:

Pulse sequences Patient care and safety 2: Examination areas Gating and respiratory compensation techniques Pelvis Head and neck

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