Pitfalls in computed tomography of the cervical and lumbar spine

The Usefulness of Dual-Layer Spectral Computed Tomography for Myelography: A Case Report and Review of the Literature

We describe a case of lumbar stenosis in which retrospective spectral analysis using dual-layer spectral detector computed tomography (CT) had the ability to expand the evaluable region in the spinal canal. Spinal canal stenosis is a common condition whose symptoms (such as lower back and leg pain with walking) deteriorate the quality of life. Generally, magnetic resonance imaging (MRI) and CT myelography are performed to diagnose canal stenosis. Dual-layer spectral detector CT can yield virtual monochromatic imaging and retrospective on-demand spectral analysis without a prescan setting. Spectral analysis could expand the evaluable region in the spinal canal for increasing the contrast enhancement in the canal.

Sonographic characterization of the lumbar intervertebral disk with anatomic correlation and histopathologic findings

OBJECTIVE

The purpose of this study was to describe the normal anatomy and abnormalities of the lumbar intervertebral disk with sonography in cadaveric specimens and to correlate the sonographic findings with pathologic findings.

METHODS

Sonographic imaging with both 4.5- and 10-MHz linear array transducers was performed on 35 lumbar intervertebral disks in 13 human cadaveric spines. The cadaveric specimens were sectioned for anatomic and histopathologic evaluation. Findings on anatomic sections were correlated with the findings on corresponding sonographic images with respect to the sonographic appearance of disk components in 30 intervertebral disks.

RESULTS

High-resolution sonography with a 10-MHz frequency transducer enabled distinction of the nucleus pulposus from the annulus fibrosus and assessment of the echogenic characteristics of these structures. Sonography showed numerous fine linear echoes in the outer portion of the intervertebral disk in 26 (87%) of 30 specimens, which corresponded to the normal concentric arrangement of the fibers in the periphery of the annulus fibrosus. Amorphous areas of low echogenicity in the inner portion of the annulus fibrosus (n = 14, 47%) correlated with degenerative changes of the disk on corresponding microscopic sections. The nucleus pulposus appeared relatively isoechoic (n = 5, 17%) or hyperechoic (n = 4, 13%) to the annulus fibrosus. In degenerative disks (n = 21, 70%), the nucleus pulposus showed decreased echogenicity, and differentiation between the nucleus pulposus and annulus fibrosus was difficult.

CONCLUSIONS

High-resolution sonography is a simple imaging method that can show the normal lumbar intervertebral disk and degenerative changes in appropriate subjects. High-resolution sonography proves superior to conventional sonography for evaluation of the lumbar intervertebral disk.

Association between postoperative outcome and results of magnetic resonance imaging and computed tomography in working dogs with degenerative lumbosacral stenosis

OBJECTIVE

To determine whether results of magnetic resonance imaging (MRI) and computed tomography (CT) are associated with postoperative outcome in working dogs with degenerative lumbosacral stenosis.

DESIGN

Prospective cohort study.

ANIMALS

12 dogs treated surgically for degenerative lumbosacral stenosis.

PROCEDURE

The lumbosacral vertebral column was examined before surgery by use of MRI and CT and after surgery by use of CT. Outcome, based on performance in standardized training exercises, was assessed 6 months after decompressive surgery. Associations between imaging results and postoperative outcome were determined by use of a Fisher exact test and logistic regression.

RESULTS

None of the dogs were able to perform their duties before surgery. By 6 months after surgery, 8 of 12 dogs had been returned to full active duty. Nerve tissue compression was effectively localized by use of CT and MRI. Significant associations between results of imaging studies and postoperative outcome were not identified.

CONCLUSIONS AND CLINICAL RELEVANCE

Surgical intervention is justified in high-performance working dogs with degenerative lumbosacral stenosis. However, results of imaging studies may be less important than clinical or surgical factors for predicting outcome in affected dogs.

Subclinical CT abnormalities in the lumbosacral spine of older large-breed dogs

Computed tomography (CT) of the L5-S3 vertebral levels was performed in six, large-breed dogs presented for problems unrelated to the lumbosacral spine. All dogs were asymptomatic for lumbosacral stenosis on neurologic examination. Breeds included German Shepherd, Golden Retriever, Boxermix and Belgian Malinois. Ages ranged from 5-12 years. Five out of six dogs exhibited CT abnormalities. Among the 18 disc levels examined, the most common findings were idiopathic stenosis, loss of vertebral canal epidural fat, and nerve tissue displacement. Less common abnormalities were vertebral canal or foraminal bone proliferation, loss of intervertebral foramen fat, vertebral canal disc bulging, degenerative articular process joint disease, transitional vertebra, dural ossification, foraminal disc bulging, Schmorl's nodes, calcified extruded disc fragment, and sacroiliac joint osteophytes. Vertebral subluxation was absent in all dogs. Findings indicate that some lumbosacral CT abnormalities may be clinically insignificant, especially in older dogs.