Fig. 3.1 Right paracentral disk herniation at L5–S1, evaluated on high-resolution thin section imaging at 3T. One problem in MR regarding the evaluation of disk herniations is the large thickness of the slice relative to the disk and relevant portion of the affected nerves. Illustrated are contiguous high in-plane spatial resolution 2-mm thick axial images. Here, the right S1 nerve root (arrows) can be followed on each section, initially exiting from the thecal sac, subsequently being compressed and displaced (both posteriorly and laterally) to varying degrees by the adjacent disk herniation, and subsequently recovering its normal shape just prior to its exit in the neural foramen.

Fig. 3.2 Pancoast (superior sulcus) tumor. An apical soft tissue lung mass is noted, seen both in the sagittal (part 1) and axial (part 2) planes, with extensive involvement of the chest wall, ribs, and adjacent spine (specifically the facets, transverse process, pedicle, and lateral vertebral body). There is no spinal canal compromise. The lesion demonstrates inhomogeneous contrast enhancement, with the suggestion of a central necrotic (nonenhancing) component. An apical lung mass with adjacent bone involvement should be considered to be bronchogenic carcinoma unless otherwise proven.

Fig. 3.3 Transitional vertebra. Lateral and AP radiographs are presented in a patient with a sacralized L5. The count was established on the basis of the chest x-ray. There were 12 rib-bearing vertebral bodies, with the left rib at T12 small, and the right rib vestigial (and poorly visualized on the AP view). Nonsegmentation of L5 and the sacrum bilaterally is well seen on the AP radiograph. The lateral radiograph demonstrates the L5–S1 disk space to be small, and absence of the normal sacral curvature. Both findings can be key to recognition on MR of a transitional vertebra at the lumbosacral junction.

Fig. 3.4 Congenital cervical vertebral body nonsegmentation (single level). Well seen on sagittal and coronal CT is nonsegmentation of C4–5. Note in this instance that there is nonsegmentation both anteriorly (vertebral body) and posteriorly (arrow, spinous process). The vertebral body segment is slightly narrowed in the AP dimension at the level of nonsegmentation, a characteristic finding. On CT there is little evidence of a residual disk space, which is typically more evident on MR.

Fig. 3.5 Posterior fusion defect of C1. There is incomplete ossification of the arch of C1 posteriorly along the midline (arrow), seen on sagittal and axial CT. The margins of the defect are well corticated. This common congenital variant should not be mistaken for a fracture.

Fig. 3.6 Os odontoideum. This anatomic variant is illustrated on both sagittal CT and MR images. The well-corticated os (arrow) lies above a hypoplastic odontoid process. Note the corticated margins on CT, the lack of edema on MR, and the hypertrophic anterior arch of C1, all characteristic for this variant, and distinguishing it from an acute type II odontoid fracture.

Fig. 3.7 Congenital lumbar spinal stenosis. Despite evidence of mild degenerative changes, including disk dehydration and loss of disk space height, there is no compromise of the canal due to disk disease. The spinal canal is, nevertheless, small in AP dimension. Congenitally shortened pedicles—the etiology of this finding—are evident in the axial image. For the clinician recognition of this entity is important, as a congenitally narrowed canal will amplify the severity of any degenerative findings or trauma. Note the incidental limbus vertebra (arrow), involving L3 anteriorly and superiorly.

Fig. 3.9 Conjoined nerve root. This common entity has many variants, with the most frequently seen being that in which two nerves arise within a single root sleeve, which subsequently divides, with the respective nerves then exiting separately in the appropriate foramina. Illustrated is a conjoined L5–S1 nerve root sleeve on the left. The sections chosen show the two nerves (L5 and S1, labeled) on the left just after separation (arrow), on the slice just caudal to this (middle column), and then on a final more caudal axial slice (right column) where relative symmetry of right and left has been reestablished.

Fig. 3.10 Type II spinal meningeal cyst (Tarlov perineural cyst, thoracic). Small cysts such as that illustrated are commonly noted on cervical and thoracic MR exams, as seen on the right at a lower thoracic level, and are incidental findings.

Fig. 3.11 Type II spinal meningeal cysts (Tarlov perineural cysts). Tarlov cysts are the most frequently encountered spinal meningeal cysts in clinical practice. Such lesions typically involve the sacral nerve roots, and demonstrate CSF SI on all pulse sequences. In the example presented, Tarlov cysts involve the S2 and S3 nerve root sleeves on the right. Foraminal enlargement and posterior scalloping of the vertebral bodies are common.

Fig. 3.13 Lateral meningoceles, neurofibromatosis type 1, CT. Sagittal and coronal reformatted CT scans (part 1) depict prominent scalloping of the L4 and L5 vertebral bodies, which can be identified as chronic in nature due to the thin sclerotic bony margin. The density therein was fluid (CSF) by attenuation measurement. In this patient, the meningoceles extended far beyond the spine into the adjacent soft tissues, with only the medial margin (white arrows) of their soft tissue extent identified on this cropped image. Volume rendering of the CT dataset (part 2) demonstrates both the vertebral body scalloping as well as thinning and deformity of the pedicles.

Fig. 3.14 Congenital cervical spinal stenosis. Sagittal images identify a reduced AP dimension to the cervical spine, with little CSF either anterior or posterior to the cord. Axial images are presented at the C4–5 and mid C5 levels. At C4–5 a broad-based disk osteophyte complex leads to moderate spinal canal stenosis with moderate cord flattening, which otherwise in a patient with a normal diameter canal would have had little impact. Note also that even at the mid C5 level there is markedly reduced CSF anterior and posterior to the cord, on axial imaging, with mild to moderate cord flattening.

Fig. 3.15 Congenital scoliosis. Two curves are present, the first convex to the left in the cervical spine, and the second convex to the right in the thoracic spine. However, this is different from the more common idiopathic S-shaped scoliotic curvature, which is thoracolumbar in location, with the thoracic component convex to the right. There are nonsegmentation anomalies involving the skull base and upper cervical spine, together with an anomalous upper thoracic vertebral body (representing nonsegmentation of a normal vertebra and a hemivertebra) at the apex of the lower curvature.

Fig. 3.16 Butterfly vertebral body. Coronal and axial images well depict a not uncommon vertebral body anomaly, a “butterfly” vertebral body. In this entity, there is failure of fusion of the two halves of the vertebral body due to persistent notochordal tissue centrally.

Fig. 3.17 Tethered cord with a lipoma (retethering). This 12-year-old child had surgery at 2 years of age, with release of a tethered spinal cord and excision of a lipomeningocele. On the current exam, there is retethering, with the cord taunt and extending to a residual lipoma in the low sacral region. There is evidence of bony spinal dysraphism posteriorly.

Fig. 3.19 Chiari I with extensive, marked hydromyelia. Wedge-shaped cerebellar tonsils are noted extending well below the C1 level. There is little if any CSF surrounding the brainstem at the level of the foramen magnum. There is marked dilatation of the central canal of the spinal cord, with a characteristic haustral-like appearance and the cord substance itself compressed peripherally. Complete evaluation of the cord from the foramen magnum to the conus is important in such cases, to establish the caudal extent of the central canal dilation, which may extend to the conus.

Fig. 3.20 Normal central canal of the spinal cord. The central canal can be visualized on high-resolution MR images in some individuals, as seen on sagittal and axial images, appearing slightly prominent size wise but within the spectrum of normal.

Fig. 3.22 Meningomyelocele, at birth. The midline sagittal T2-weighted image from the MR exam of this newborn, on the first day of life, is presented. A large spinal defect is noted posteriorly in the low lumbar region, with a CSF-filled sac protruding dorsally. It is very rare to ever see such a case on MR, given that surgery (repair with closure) is performed almost immediately. By definition, this defect lacks a skin covering, with neural tissue (and specifically the CSF sac) exposed to air.

Fig. 3.23 Tethered cord in a patient with a Chiari II malformation. The typical tethered cord patient presents with neurologic dysfunction early in life, with many cases repaired at birth. Retethering may occur, as illustrated. The cord gradually tapers until reaching the end of the thecal sac, with no distinct conus—a typical appearance for either simple tethering or retethering. Nearly all Chiari II patients present at birth with a meningomyelocele, as was the case with this child.

Fig. 3.24 Lipomyelocele. A single sagittal midline T2-weighted image demonstrates the cord extending to and tethered in the sacral region, without a change in caliber. There is an extensive posterior bony sacral defect, through which the cord continued terminating in a neural placode (visualized on adjacent off midline images, not presented) within the large dorsal lipoma.

Fig. 3.26 Diastematomyelia. Sagittal, coronal, and axial MR images depict multiple nonsegmented midthoracic vertebral bodies, two hemicords, and on the final axial image a bony spur separating the two cords. Vertebral segmentation anomalies are common with diastematomyelia, in particular block vertebrae, and thus the presence of the latter finding (on plain film or CT) should raise the question of diastematomyelia.

Fig. 3.28 Anterior sacral meningocele. Sagittal, coronal, and axial T2-weighted scans demonstrate a small presacral CSF collection contiguous with the thecal sac. There is also mild hydromyelia involving the distal cord, seen on the sagittal image. Characteristic accompanying findings include hypoplasia of the sacrum and, in the coronal plane, a curved “scimitar” shape to the sacrum. The Currarino syndrome (triad), present in this patient, consists of an anorectal malformation (typically with constipation), bony sacral defect, and presacral mass (anterior meningocele or benign teratoma). Note the dilated stool-filled rectum, reflecting the third part of the triad in this patient.

Fig. 3.29 Dorsal dermal sinus. Sagittal midline images are presented in this infant, the first being at 2 months of age (left most image). Additional images (T1- and T2-weighted, and DWI – insert) are provided from a second exam at 9 months of age. On the initial exam a sinus tract is noted extending from the skin, posteriorly, to the thoracic cord. There is a small associated intradural lipoma. On the follow-up exam, the sinus tract is again noted, but now well seen is an intramedullary lesion, with low and high SI respectively on T1-and T2-weighted images, and restricted diffusion (high SI on DWI). This abnormality corresponds to a growing epidermoid (with an epidermoid or dermoid found, in association, in 50% of dermal sinus cases), which was resected a few weeks following the second exam.

Fig. 3.31 Idiopathic spinal cord herniation. The sagittal T2-weighted scan demonstrates focal anterior displacement (kinking) of the cord in the midthoracic region. On the axial scan, the cord is noted to have prolapsed through an anterolateral dural defect. The patient presented with spastic monoparesis of the right leg. Findings were confirmed at surgery, with reduction of the herniation.

Fig. 3.33 Vertebral body scalloping, neurofibromatosis type 1, MR. There is posterior scalloping of L4, and to a lesser degree L5 (without any associated mass), seen on axial and sagittal images. Spine manifestations of NF1 include scoliosis, bony dysplasia, dural ectasia (with vertebral scalloping), and lateral meningoceles.

Fig. 3.34 Neurofibromatosis type 1, CT. Sagittal and coronal reformatted CT sections demonstrate the neural foramina of the cervical spine to be diffusely enlarged, due to the presence of plexiform neurofibromas.

Fig. 3.35 Neurofibromatosis type 1, MR. There is diffuse enlargement of lumbar nerve roots within the neural foramina (which are also slightly enlarged), consistent with a diagnosis of NF1. The lesions are hyperintense on the T2-weighted scan, and demonstrate moderate contrast enhancement. This adolescent male patient has extensive plexiform neurofibromas, meeting the clinical criteria for diagnosis on this basis together with the presence of multiple café-au-lait spots.

Fig. 3.36 Neurofibromatosis type 2. Three small intramedullary lesions, with high signal intensity on the T2-weighted scan and abnormal enhancement post-contrast, are noted within the cervical cord, consistent with either small astrocytomas or ependymomas, both which occur in NF2. Note also the small enhancing meningioma, with a broad dural base adjacent to the posterior arch of C1.

Fig. 3.37 Klippel-Feil syndrome. On the sagittal image, the C2–C4 vertebral bodies are hypoplastic and nonsegmented, with absence of normal intervening disk spaces. Diastematomyelia is identified on the axial scan at C1–2, with the two hemicords tethered by a fibrous band and enveloped in a single arachnoid-dural sheath.

Fig. 3.38 Multiple cervical vertebral anomalies. Seen on sagittal and coronal MR these include hemivertebrae (C5, C6), nonsegmentation of the posterior elements (C1–2), and a wedge-shaped vertebral body (C7). A large osteophyte at C2–3 reflects accentuated movement at this level, with mobility of the cervical spine otherwise evidently restricted.

Fig. 3.40 Interspinous ligament injury. On CT, this injury is visualized only indirectly by widening of the interspinous distance (*). On MR, edema within the ligament can be directly visualized (arrow), with the extensive posterior paraspinous edema/hemorrhage an additional indication of the severity of the injury in this patient.

Fig. 3.41 Traumatic C3 burst fracture. An axial load injury has resulted in a burst fracture of C3, with mild loss of height and edema seen throughout the vertebral body. A vertically oriented, fracture plane is seen on the sagittal T2-weighted image extending through the C3 vertebral body. Retropulsion of the posterior portion of the C3 vertebral body into the spinal canal results in mild spinal canal compromise with mild cord flattening. There is no evidence of cord edema in this region. Edema in the posterosuperior portion of the C4 vertebral body is consistent with an additional acute fracture. Prevertebral soft tissue edema (only partially depicted) extended from the skull base to the C4 level.

Fig. 3.43 C1 fracture. Because C1 is a ring, when fractured there will typically be at least two fracture lines (as in this instance, with fractures of both the anterior [black arrow] and posterior [white arrow] arches). The Jefferson fracture, of which this is an example, is a burst fracture due to axial loading.

Fig. 3.44 Type I odontoid fracture. There is a mildly distracted fracture involving the tip of the odontoid, seen on sagittal and coronal reformatted images. A type I fracture involves only the superior portion of the dens, as distinguished from a type II fracture that involves the base of the dens (not illustrated). In this patient, there is likely an additional atlantoaxial dissociation injury, with increased distance between the articular facets of C1 and C2 on the right.

Fig. 3.46 Traumatic spondylolisthesis of C2 (hangman fracture). Sagittal images reveal coronally oriented fractures (arrows) bilaterally of the pars interarticularis of the axis (C2). In this instance there is little displacement or angulation.

Fig. 3.47 Clay-shoveler fracture. Sagittal and axial CT images (part 1) depict a slightly displaced acute fracture of the C7 spinous process. Note the very sharp discontinuity of cortical bone, best seen on the axial section, defining this fracture as acute. On sagittal MR (part 2), the fracture of the spinous process can be identified (white arrow), but is more difficult to detect than on CT. Note the relative absence of edema within the bone adjacent to the fracture line, a common but nonintuitive finding in acute trauma. What CT does not depict however is the extensive nature and severity of the injury, reflected by the diffuse edema in the posterior paraspinal tissues (*) and the prevertebral edema/fluid (black arrow).

Fig. 3.49 Compression fractures, acute, cervical spine. In trauma, a vertebral body may wedge anteriorly due to flexion. Or, with excess axial load, a compression (burst) fracture may result—this being the most common traumatic injury in the thoracic spine. The latter may manifest as a loss of vertebral body height, as seen in the T3 vertebral body (lower white arrow). However, body height may be maintained, rendering visualization impossible on plain film or CT. With MR these microfractures are easily identified due to marrow edema, in this instance with low signal intensity (upper arrow) on the T1-weighted scan within C7.

Fig. 3.50 Severe hyperflexion injury, CT. Midline and right lateral sagittal reformatted CT images are presented (part 1), along with a single axial image at the C4 level (part 2). There is a fracture involving the left C4 lamina extending into the articular pillar and transverse foramen. The C4–C5 facet on the right is perched. Splaying of the C4–C5 spinous processes, consistent with interspinous ligament injury and instability, is also noted. Together these result in 4 mm of anterolisthesis of C4 on C5 with a mild acute kyphotic angulation at this level. This anterolisthesis and a broad-based disk bulge at the C4–5 level (not well seen on the images presented) result in mild AP dimension spinal canal narrowing at this level. Given the extent of injury, likely the entire posterior ligamentous complex is disrupted at C4–5.

Fig. 3.51 Severe hyperflexion injury, MR. On the midline sagittal MR image, there is a traumatic anterolisthesis of C4 on C5, with an acute disk herniation, leading to mild canal narrowing and cord compression. There is splaying of the C4–5 spinous processes, and edema between, consistent with disruption of the interspinous ligament. On the off-midline image, a perched facet is also noted (arrow), implying at least an additional tear of the interfacetal ligaments.

Fig. 3.52 Burst fracture, acute, thoracic spine, CT. Sagittal, coronal (part 1), and axial (part 2) reformatted CT images are presented of the midthoracic spine, in the acute time frame following trauma. There is moderate loss of height of T7, with mild anterior wedging. Portions of the vertebral body are displaced (on the sagittal image) both anteriorly and posteriorly, and (on the coronal image) both to the left and right. Note the centrifugally located vertebral body fragments, best appreciated on the axial image.

Fig. 3.53 Compression fracture, acute, L1 (CT). On the sagittal reformatted image, a mild anterior wedge compression deformity is noted, with an acute fracture suggested only indirectly (in this plane) by the sclerotic line (black arrow). This corresponds to compressed trabecular bone. CT is excellent for demonstration of acute fracture lines, in particular where they intersect cortical bone (small white arrow, axial plane), but insensitive to marrow edema and microfractures, which are well depicted by MR.

Fig. 3.54 Compression fracture, acute and chronic, lumbar spine (CT). There is generalized osteopenia. There is an acute compression fracture of L3 with discrete fracture lines identified (arrows). There is approximately 50% loss of vertebral body height. There is moderate retropulsion of the posterior superior portion of the L3 vertebral body into the spinal canal. This leads to approximately one-third to one-half loss of bony central spinal canal dimensions in the AP direction. However, the level of canal compromise should be well below the termination of the conus, which could not be determined on this CT. Also demonstrated is a chronic anterior wedge compression deformity of L4, with the time frame of this deformity established by its presence on a prior exam. There is mild retropulsion of the superior posterior portion of this vertebral body into the spinal canal.

Fig. 3.55