Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Radiología. 2011;53(2):116-133

ISSN: 0033-8338

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UPDATE

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies

F. Ruiz Santiago,* M.M. Castellano García, L. Guzmán Álvarez, M. Tello Moreno

Sección de Radiología Musculoesquelética, Servicio de Radiodiagnóstico, Hospital de Traumatología, Ciudad Sanitaria Virgen de las Nieves, Granada, Spain

Received 7 May 2010; accepted 22 October 2010

KEYWORDS Abstract The use of tomographic imaging techniques, computed tomography (CT) and Spine; magnetic resonance imaging (MRI), to complement or replace plain-fi lm radiography in the Magnetic resonance study of spine pain is becoming more and more common. imaging; The aim of this paper is to provide a general review of the CT and MRI manifestations of the Column; wide spectrum of lesions that can cause pain in the spinal column. This spectrum includes Computed degenerative disease, malalignment, tumors, inflammatory processes, and infectious tomography; processes. ; Precise knowledge and accurate reporting of the fi ndings at CT and MRI are fundamental for Spinal column clinical decision making in patients with spine pain. disease; © 2010 SERAM. Published by Elsevier España, S.L. All rights reserved. Curvature of the spine

PALABRAS CLAVE Tomografía computarizada y resonancia magnética en las enfermedades dolorosas Columna; del raquis: aportaciones respectivas y controversias Resonancia magnética; Resumen Las técnicas de imagen tomográfi cas, tomografía computarizada (TC) y resonancia Raquis; magnética (RM) se vienen usando cada vez de forma más frecuente, en sustitución o adición a Tomografía la radiografía simple, para el estudio del dolor de espalda. computarizada; El objetivo de este trabajo es realizar una revisión general de las manifestaciones en TC y RM Dolor de espalda; del amplio espectro de enfermedades que pueden ser responsables del dolor generado en la Enfermedades columna vertebral. Este espectro abarca la enfermedad degenerativa, de la alineación vertebral, de la columna; tumoral, infl amatoria e infecciosa. Curvatura espinal El conocimiento y la descripción exacta y uniforme de los hallazgos con dichas técnicas suponen un soporte fundamental para la toma de decisiones clínicas en los pacientes con dolor de raquis. © 2010 SERAM. Publicado por Elsevier España, S.L. Todos los derechos reservados.

* Corresponding author. E-mail: [email protected] (F. Ruiz Santiago). 0033-8338/$ - see front matter © 2010 SERAM. Published by Elsevier España, S.L. All rights reserved. Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies 117

Introduction perfusion, in-phase and opposed-phase sequences, etc. Their use is less common and usually reserved for tumor The expanding use of tomographic imaging techniques, imaging. 7 computed tomography (CT) and magnetic resonance imaging (MRI), has led to a relative decline in the use of plain chest radiography as the first imaging technique in multiple Clinical and radiological considerations conditions that manifest with back pain. 1 Clinical guides do not recommend systematic imaging in Spine CT and MRI studies in asymptomatic patients have patients with acute or chronic back pain in the absence of reported a high percentage of vertebral disc disease. On warning signs (red fl ags), since this does not signifi cantly the other hand, there are also symptomatic patients that improve the clinical outcome. 2 Only in the presence of show no pathological changes on imaging studies. 9 warnings signs (fever, weight loss, history of tumor or Many of these disorders are age-related and may be neurological disorders) imaging techniques assume a central asymptomatic or show a symptomatic period of variable role. duration that may sometimes become chronic. One of the Inter-reader variability in the interpretation of the great challenges of imaging techniques is to reliably fi ndings is one of the factors that lead to disagreement in differentiate between symptomatic and asymptomatic 3 the decision-making process. In the present work, we conditions. Modic changes, particularly type I, seem to be assess the diagnostic contributions, advantages and strongly associated with back pain, whereas weaker limitations of CT and MRI in the evaluation of painful spinal association is found with disc disorders. 10 As for facet conditions. joint , some authors consider it rare in asymptomatic patients, 11 but others fail to find a statistically signifi cant association between this condition Technical considerations and back pain. 12

CT provides high spatial resolution for anatomical imaging and it is particularly indicated in the evaluation of bone Causes of back pain lesions. From imaging acquisition in the axial plane, multidetector computed tomography (MDCT) allows for The causes of back pain can be classifi ed into mechanical isotropic images with no significant spatial distortion in and non-mechanical. Mechanical pain is secondary to 4 multiplanar and 3D reconstructions. anomalous stress and tension on the spine and may be Spine CT imaging must include a continuous helical triggered or worsened by certain movements or physical scanning across the range of interest, which is determined activities. 13 It accounts for 97 % of the causes of vertebral by clinical criteria or by the presence of a lesion previously pain, including sprain, degenerative disc and facet joint identified by other imaging techniques. Submilimeter disease, , and osteoporotic slices allow for isotropic images; however, for extensive fractures. Non-mechanical causes account for 1 %, studies, reconstruction thickness of 1-3mm may be including infl ammatory, infectious and tumor diseases. 14 acceptable. Pain secondary to trauma fractures, surgery and referred The major drawback of CT is radiation dose, much pain secondary to visceral lesions are excluded from this higher than that of conventional radiography, and it may study. range between 13-26 mSv depending on the instrumentation 5 and technical parameters. The use of low-dose CT with Sprain or soft tissue strain (fi g. 1) radiation levels of around 1 mSv is not universally spread. 6 Muscle strain and sprain are the most common MR imaging offers better characterization of soft-tissue causes of acute and cervical pain in the general structures than CT. A standard protocol should include axial population. 14,15 and sagittal T1 and T2 sequences and, at least, one Muscle pain may appear without previous trauma or fat-suppressed T2-weighted sequence, based on techniques may be secondary to trauma strain or direct muscle of chemical shift and/or of inversion-recovery suppression. contusion. In muscles and , the severity of the Concerning the cervical spine and due to the smaller size of lesions ranges from overstretching to partial or complete the discs, the axial gradient echo sequence is recommended, rupture. which usually allows differentiation between disc Spine imaging is indicated only in cases of sprain secondary (hyperintense) and osteophytes (hypointense). 7 In case of to injury severe enough to make us suspect a spinal fracture, suspected infl ammatory, infectious or neoplastic disorders, in instability secondary to ligament rupture, or damage to the examination is completed with additonal T1 sequences nervous structures. obtained after gadolinium administration. Fat suppression MRI demonstrates edema of the paravertebral muscles in at least one plane allows better enhancement evaluation that may resolve or progress to atrophy of the involved of these pathological processes. 8 muscles. 16 In more severe cases, MRI shows ligament and Innovative MRI techniques are being developed that try capsular involvement or signs associated with instability, to provide metabolic, functional and physiological including interspinous widening, vertebral subluxation, information to the anatomical image of the standard vertebral compression fracture and loss of cervical methods. Some of these techniques are diffusion, . 17 Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

118 F. Ruiz Santiago et al

Figure 1 Lumbar sprain. Axial T1 W (A) and T2 W (B) images show edema in the paravertebral muscles (multifi dus muscle) (arrows) and atrophy in the area of the lumbar rotator muscles (*). C) Sagittal T2 image show yellow ligament rupture and disc herniation (arrows) following hyperfl exion injury. D) Cervical sprain. Sagittal STIR image demonstrates interspinous edema (arrow) in a patient with severe osteochondrosis and subchondral bone edema C5-C6 (*).

Facet joint disease (fi g. 2) Degenerative disc disease

CT provides detailed imaging of the structural lesions Degenerative disc disease has two basic patterns: secondary to facet joint degeneration: osteophytes, deformans and intervertebral osteochondrosis. The former subchondral sclerosis and geodes, facet joint impingement, involves essentially the annulus fi brosus and epiphyseal rings while capsular and ligamentous calcifi cations. MRI understimates the disc height remains normal, and it is considered a consequence bone changes but is very sensitive to the presence of joint of the natural aging of the disc. Intervetebral osteochondrosis effusion, synovial cysts or bone edema. 18 Increased involves the disc, endplates and subchondral bone. 24 intra-articular fl uid 19 and facet edema 20 are associated with MR is the most sensitive technique for the detection of instability of the involved segment and with the presence of early changes secondary to this condition. 25 symptoms. 20,21 T2-weighted sequences show a progressive loss of the Synovial cysts extending into the paravertebral muscles homogeneous hyperintensity of the nucleus pulposus or into the spinal canal may result in nerve compression. progressing to a loss of differentiation between nucleus MRI reveals the fluid content (synovial or hemorrhagic) pulposus and annulus fi brosus. The disc losses height and of the cyst, while TC is better for air content or extends beyond the endplate margins contributing to calcifi cations. 22,23 marginal osteophyte formation. Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies 119

Figure 2 Facet joint disease. A) CT scan shows arthrosis with void phenomenon and subchondral erosions. B) Axial T2. Paravertebral synovial cyst (*). C) and D) T1 and STIR sequences show a facet edema pattern (arrows).

Figure 3 Annular tears. Sagittal T2-weighted MRI shows a concentric (A), transverse (B) and radial tear with extrusion (C). D) Sagittal CT scan shows transverse tear in L3-L4 and radial tears in the two lower discs (arrows). Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

120 F. Ruiz Santiago et al

Figure 4 Disc disease in the axial plane. T2 MRI. A) Normal disc. B) Bulging disc. C) Focal central protrusion (arrow). D) Paramedial or subarticular protrusion (arrow). E) Foraminal extrusion (arrow). F) Extraforaminal extrusion (arrow).

Three distinct types of annular tears have been described: is still not universally accepted. In the axial plane, the disc concentric, transverse and radial. Concentric tears result may be classified as normal, bulging, protruded and from the separation of the lamellae of the annulus. extruded. 24 Protrusion and extrusion are also described Transverse tears are horizontal fissures that occur in the according to their position in the axial plane. In 90 % of cases periphery of the annulus close to the endplates. Both types they are central or paramedial (subarticular in the new of tears are common fi ndings in autopsy studies of individuals nomenclature), and foraminal and extraforaminal in 10 % of older than 60 and they are considered manifestations of the cases (fi g. 4). spondylosis deformans or aging of the disc 26 (fi g. 3). The term bulging disc refers to a deformity ≥ 180° of the Radial tears extend from the nucleus through the annulus circumference of the entire disc. This bulging usually and are not age-related. They are associated with loss of extends < 3 mm beyond the outer ridges of the endplates. 24 chondroid matrix, disc impingement and instability, and are Protruded disc refers to a deformity or displacement < 180° considered the critical factor in the genesis of intervertebral of the circumference of the disc where the nucleus pulposus osteochondrosis. 27 is presumably contained by the annulus. The term focal Annular tears have been described in 39 % of people who protrusion refers to protrusions involving less than 25 % of suffer from lumbar pain, and most commonly involve the circumference of the disc, otherwise the term diffuse or L4-L5 and L5-S1 levels. 28 CT is not very sensitive; however, it broad-based protrusion is used. In the sagittal plane, the can depict these tears when occupied by air or fluid. On distance between the edges of the protruded material must T2 MRI sequences, tears appear as linear areas of high not be more than the distance between the edges of the signal. Some authors have found correlation between disc of origin and, in the axial plane, the diameter of high-intensity signal and clinically active lesion, 29 while the protruded material must not be more than the diameter others have found no correlation. 30 of the neck or the base. 31 Disc disease nomenclature is still a matter of debate. The Extrusions are focal abnormalities in which the nuclear project of nomenclature of the North American Spine Society material extends beyond the entire annulus fi brosus. In the Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies 121

Figure 5 Disc disease in the sagittal plane. T2 MRI. A) Protruded disc. The disc does not extend beyond the endplates. B) Extruded disc. The disc exceeds the height of the disc. C) Extruded disc that migrates cranially (arrow). D) Contrast-enhanced sagittal T1 MRI. Sequestrated disc in the central canal (arrow).

Figure 6 Modic changes. Sagittal T1 (A), T2 (B), STIR (C) and CT scan (D) show type III sclerotic changes (arrows) surrounded by type I edematous changes in a patient with listhesis. Sagittal T1 (E), T2 (F), STIR (G) and CT (H) sequences in a patient with fatty changes in type II. CT scan only shows the presence of sclerosis in both cases. Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

122 F. Ruiz Santiago et al

Figure 7 A) Sagittal CT shows cervical Schmorl’s node (arrow). B) Sagittal CT scan shows lumbar Schmorl’s nodes (arrows). Posterior marginal herniation (arrowhead). C) Sagittal STIR MR imaging shows Schmorl’s node and mild edema (fl echa). D) Sagittal T2 MRI sequence shows posterior marginal disc herniation (arrowhead) and endplate irregularities (arrows) in a patient with lumbar Scheuermann disease.

sagittal plane, the distance between the edges of the disc Table 1 Radiological signs that help differentiate material is greater than the height of the parent disc, or between pathologic and insuffi ciency fractures. the extruded fragment shows at least one dimension greater than the base. The nuclear material may migrate Sign Pathologic Insuffi ciency cranially and/or caudally or maintain no continuity with fractures fractures the nucleus of origin; this is known as sequestrated disc (fi g. 5). Posterior border Convex Vertebral Focal protrusions and extrusions are traditionally referred margin as “disc herniations”. The new nomenclature considers disc retropulsion herniation a generic term that includes both protrusions and Vertebral extrusions. Cyst or fi ssure No Common Signal intensity changes in subchondral marrow of the Intravertebral Paravertebral and/or Asymmetric No/Fine vertebral endplates are associated with disc degeneration epidural mass symmetric and were divided into three groups by Modic et al. 32 Type I Edema pattern Diffuse, patchy Band-like changes demonstrate subchondral edema with decreased or nodular low signal on T1 and increased signal on T2 and STIR Spared areas Uncommon Common sequences. These changes correlate well with lumbar pain of marrow and instability. 33 Cortical or trabecular Uncommon Common Type II changes involve instability and lipid marrow fracture replacement. They are represented by increased signal on Cortical or trabecular Common Uncommon T1 and T2 that is suppressed on STIR sequences. Type III destruction changes correlate with bone sclerosis at radiography and CT, and show decreased signal on all MRI sequences. Studies on Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies 123

Figure 8 Sagittal T1 (A) and T2 (B) images show central canal stenosis and myelopathy (arrow). C) Axial T2 image shows central canal stenosis (arrow). D) Sagittal T2 image shows foraminal stenosis (arrow). E) Coronal CT. Uncarthrosis (arrow). F) Sagittal CT. Uncarthrosis with foraminal stenosis (arrows).

the correlation between MRI-CT have demonstrated that Schmorl’s nodes are defi ned as herniations of the nucleus endplate sclerosis exists in all types of Modic types, pulposus into the endplates. They are more common in the particularly in mixed changes. MRI is not sensitive to thoracic than in the lumbar spine. On CT and MRI Schmorl’s sclerosis detection 34 (fi g. 6). nodes appear as bone defects of the endplates into which Modic changes are considered different stages of the same the disc herniates. 38 When they occur between the endplate pathological condition. Conversion from one type to another and the epiphyseal ring, they are known as postero marginal may occur, mixed types probably being intermediate stages herniation or limbus (fi g. 7). of this conversion. Conversion from type I into type II is the most common. 35 Spinal stenosis (fi g. 8) Modic changes occur in 20-50 % of patients with and their incidence increases with age. 36 However, Spinal canal stenosis most often results from degenerative these changes are present in 10-25 % of asymptomatic changes in the spine. A congenitally narrow canal promotes patients, 37 although with different distribution and early development of symptoms secondary to disc and facet morphology. In these patients, the changes are usually focal degeneration. 39 and located at the anterior superior endplates of the MRI provides similar information to that of a CT myelogram mid-lumbar spine, with preserved adjacent disc. In for the assessment of the causes of stenosis. However, the symptomatic patients, the lower back is most commonly myelogram provides higher resolution images of the osseus affected and the changes appear in the endplates adjacent component and its imprint on nervous structures. MRI to a degenerated disc. provides direct visualization of nerves and . Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

124 F. Ruiz Santiago et al

Figure 9 A-D) Osteoporotic insuffi ciency fractures. Sagittal CT scan shows subchondral sclerosis bands (A) that correspond to bandlike edema pattern on STIR sequence (arrows) (B). Sagittal CT (C) and sagittal STIR (D) show intervertebral fi ssure (arrow) and retropulsion of the posterior superior margin (black arrow). E) and F) Pathologic fractures. Sagittal CT scan shows renal carcinoma metastasis (E) and sagittal T2 (F) image shows lung metastasis, with convex posterior margin (arrow).

Increased intramedullary signal on T2 weighted and STIR root deviation and root compression between the disc and sequences is often seen in patients with myelopathy the posterior osseous structures. 41 As for foraminal stenosis, suggesting edema, ischemia, myelomalacia or cystic obliteration in the vertical or transverse direction is degeneration. 40 considered mild stenosis and obliteration in both vertical Spinal stenosis may occur in the central and/or lateral and transverse axis with no deformity of the nerve root is canal. In the lumbar spine, a sagittal diameter < 12 mm considered moderate. Severe stenosis shows morphological is very suggestive of stenosis; 8 however, the axial area changes secondary to compression. 42 of the thecal sac is considered more effective in the The estimated minimum sagittal diameter of the cervical diagnosis of stenosis. In this respect, values < 76mm 2 are spinal canal between C3 and C7 is 12mm. Lower values considered severe stenosis and 76-100 mm 2 are considered increase the risk of degenerative spinal stenosis. 43 In the moderate. 41 foramen, uncarthrosis is the main cause of stenosis. In the lateral canal, the stenosis may occur at the proximal Uncinate joints are found from C2-C3 to C6-C7 and they entrance of the root or lateral recess, or at the exit or hypertrophy as a result of the mechanical overload caused foramen. Nerve root involvement in the lateral recess by disc impingement. Osteophytes may project into the ranges from contact of the disc with the nerve root to nerve foramen resulting in stenosis with . 44 Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies 125

Figure 10 3D CT scans. A) Idiopathic . B) Scoliosis secondary to incomplete block (arrow). C) Scoliosis secondary to hemivertebra (arrows).

Low-energy vertebral fractures (fi g. 9) differences in the signal intensity ratio between both types of fractures have been reported. 50 Fractures secondary to tumor are called pathologic fractures PET-TC has shown an accuracy of 92 % in differentiating and those secondary to ostheoporosis, insufficiency benign and malignant fractures. This modality is considered fractures. 45 Differentiation between the two types using an additional tool in equivocal cases, 51 although biopsy, with imaging techniques is based on bone marrow signal and or without vertebroplasty, may be necessary for fi nal patient morphology of the fractured vertebra (table 1). management. On MRI, pathologic fractures usually show complete replacement of the bone marrow of the vertebral body. and scoliosis (fi g. 10) Incomplete replacement shows patchy or nodular appearance. Convex vertebral margins secondary to Scheuermann’s disease or idiopathic kyphosis accounts for tumor expansion and the presence of an asymmetric 90 % of cases of juvenile kyphosis. Diagnostic criteria for this paravertebral or epidural mass are characteristic of condition are kyphosis > 45° and at least one vertebra with malignancy. 46 wedgening > 5°. Irregular endplates and Schmorl’s nodes are In steoporotic fractures, medullary signal changes depend associated fi ndings. 52 on the age of the fracture. Accute fractures usually show Scoliosis is defi ned as a lateral curvature of the spine > 10° edema with bandlike pattern in the subchondral endplate. as measured by the Cobb method on a standing radiograph. 53 The linear image corresponding to the fracture may be often Scoliosis can be classified as congenital, neuromuscular, identifi ed within the edema pattern. Fissures and cysts with degenerative, or idiopathic, with the last being the most air or fl uid content may also appear. 47 In chronic fractures, common and usually not painful. there is reversion to normal fat signal from the bone marrow. CT is indicated for the assessment of surgical correction Retropulsion of a bone fragment toward the canal is very of congenital scoliosis. The most severe curves appear with suggestive of benignancy. 46 unilateral bars; moderate curves with hemivertebra and MRI morphological signs are usually conspicuous on CT. congenital blocks and wedged vertebrae are present in mild Fracture lines within the trabecular and cortical bone are patterns. 54 characteristic of osteoporotic fractures, while bone MRI is indicated in children younger than 10 that develop destruction is typical of pathologic fractures. 48 Pedicle scoliosis (infantile and juvenile forms) because of its frequent involvement, described in pathologic fractures, is also a association with neural axis abnormalities. 55 In general, common fi nding in insuffi ciency fractures. 49 tomographic imaging techniques are not indicated for Diffusion and perfusion techniques have been used in the adolescent scoliosis (11 to 17 years), the most common type differentiation between pathologic and insufficiency of idiopathic scoliosis, except when it is painful or unusual fractures, albeit with controversial results. In-phase/ symptoms are present, such as headache or neurological opposed-phase imaging, based on the assumption that involvement (ataxia or pes cavus). Causes of pain include malignant lesions completely replace fat, unlike benign , Scheuermann kyphosis, syringo/hydromyelia, lesions, is the most promising modality. 7 Significant herniated disc, tethered cord or bone or medullary tumors. 56 Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

126 F. Ruiz Santiago et al

Local abnormalities of the vertebral alignment in a so-called “bamboo spine”. Diffuse idiopathic skeletal (fi g. 11) hyperostosis also shows paravertebral ossifi cations but with more prominent and coarser bone bridging than ankylosing Spondylolisthesis refers to the anterior displacement of a and with no sacroiliac involvement. 65 vertebra in relation to the vertebra below. Causes of is also a typical fi nding of this group of diseases. spondylolisthesis include: 57 developmental (dysplasia), The initial sign is edema that may progress to structural trauma (stress or accute fracture), degenerative (disc and changes: erosions, subchondral sclerosis and bone bridging facet joint) and pathologic (infection, tumor). with joint fusion. STIR and contrast-enhanced T1 MRI The most severe displacements occur in dysplastic sequences, preferably with fat suppression, are the most spondylolisthesis. The most common are spondylolisthesis sensitive modalities for the detection of these infl ammatory secondary to isthmic lysis and degenerative spondylolisthesis. changes. 66 Generally, STIR sequences alone are suffi cient for Differentiating signs are summarized in table 2. detecting edema, but the enthesis, synovitis and capsulitis Multislice CT with multiplanar reconstructions is the are better characterized on contrast-enhanced T1 optimum technique for diagnosis of spondylolisthesis. MRI sequences, which are not routinely recommended except to imaging is the modality of choice to demonstrate nerve ensure maximum diagnostic confi dence in early stages. 67 impingement, generally in the lateral recess or in the foramen. 58 Meyerding classified the degree of displacement into Vertebral tumors 4 grades based on the position of the posterior margin of the The most common causes of tumor involvement of the spine upper vertebra over the upper endplate of the inferior are metastatic disease and multiple myeloma. Lymphoma vertebra, which is divided into four equal parts and leukemia are much less common. 59 posteroanteriorly. Although primary vertebral tumors are rare, accounting Retrolisthesis is also a manifestation of segmental for 3-9 % of all primary bone tumors, we review the osteoid instability usually secondary to loss of disc material osteoma, osteoblastoma, giant cell tumor, aneurysmal bone associated with intervertebral osteochondrosis and extruded cyst, osteochondroma and hemangioma. 68 nucleus pulposus. Osteoid osteoma and osteoblastoma are generally painful Baastrup’s disease refers to the development of a conditions that produce an osteoid matrix and may result neo-arthrosis between the spinous processes generally in scoliosis and abnormal gait. CT typically shows an secondary to degenerative disc disease with loss of height osteolytic lesion (nidus), which may be calcified, and alignment abnormalities. Erosions and sclerosis are surrounded by sclerosis and usually located in the posterior better depicted on CT, while MRI is useful to assess for bone elements of the spine, and on the concave side if associated 60 edema or interspinous bursitis. with scoliosis. Size is essential to differentiate between the two conditions, osteoid osteoma is < 2 cm and Seronegative spondyloarthropathies (fi g. 12) osteoblastoma > 2 cm in size. MRI shows bone and soft tissue edema that may lead to overestimation of the size Seronegative comprise a group of of the lesion and suspicion of an aggressive or malignant multisystemic infl ammatory diseases, with mainly lumbar lesion 69 (fi g. 13). and sacroiliac involvement, including Hemangiomas are tumors that occur frequently in the and spondyloarthropathies secondary to infl ammatory bowel spine. The most common lesions, which show predominantly disease, psoriasis and reactive arthritis (formerly named fatty content, are usually asymptomatic and discovered Reiter’s syndrome). 61 Patients present with infl ammatory incidentally on MRI. Therefore, they appear as areas of high back pain typically accompanied by morning stiffness that intensity signal on T1 and T2 that is suppressed on STIR improves with activity. However, degenerative disc or facet sequences. Hemangiomas with greater vascular content, disease may also present with stiffness. 62 Imaging techniques which extends to posterior elements or to soft tissues, are are thus essential for differential diagnosis. more likely to be symptomatic. They show hypo- or CT demonstrates structural bone changes (sclerosis, isointense signal on T1 and hyperintense on T2 and STIR. 70 erosion and joint fusion) but it lacks sensitivity to depict Occasionally, symptomatic hemangiomas may increase in infl ammatory changes that may be, however, visible on MRI, size and compress paravertebral and epidural soft tissues even several years before structural changes develop. 63 causing neural compression, simulating malignant or Therefore, MRI is the modality of choice in early phases and metastatic lesions. 71 in infl ammatory episodes, while MRI should be reserved for CT scanning shows sclerotic reinforcement of the structural changes. remaining trabeculae mixed with fatty and vascular areas. Enthesopathy refers to an infl ammatory process at the the These trabeculae give a polka-dot appearance in axial site of insertion of ligaments, tendons or articular capsule imaging or a latticelike pattern in sagittal imaging 72 into bone and it is a characteristic feature of (fi g. 14). spondyloarthropathies. This condition presents with edema Chordoma, chondrosarcoma, Ewing’s sarcoma and and erosions (osteitis) in the vertebral margins and in the osteosarcoma are among malignant spinal tumors. CT is the anterior longitudinal ligament insertion and it progresses to modality of choice for identifi cation and characterization of vertebral body squaring. 64 Later on, during the post-reactive the mineralization of the tumor matrix. MRI is useful for the phase, the edema pattern is replaced by fatty or sclerotic evaluation of the extent of the lesion, particularly with areas with syndesmophyte formation (paravertebral vertical soft-tissue component and involvement of the canal and ossifi cations leading to bone bridging). Late changes result neural structures 68 (fi g. 15). Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies 127

Figure 11 Isthmic lysis with spondylolisthesis. Axial T2-weighted MRI (A), sagittal central (B) and sagittal lateral CT (C) scans show the lytic process (arrows), widening of the central canal and loss of foraminal height. The spinous process step-off is formed with the upper spinous process. D), E) and F) Degenerative listhesis. Axial T2 MRI (D), sagittal central (E) and sagittal lateral (F) CT scans show slip of the articular processes (arrows), central canal stenosis and mild foramen involvement. The spinous process step-off is formed with the lower spinous process. G) Retrolisthesis (arrow) on sagittal lumbar CT. H) and I) Baastrup’s disease (arrow). Spinous neo-arthrosis on sagittal CT (H) and on sagittal STIR (I).

Table 2 Radiological signs helpful in the differentiation between degenerative spondylolisthesis and isthmic spondylolisthesis.

Degenerative spondylolisthesis Lytic spondylolisthesis

Isthmic lysis No Yes Displacement of spinous process Anterior, with the vertebral body No, or posterior displacement Spinous process step-off With the spinous process of the lower With the spinuos process of the upper vertebra vertebra Sagittal diameter of the central canal Decreased Increased Foramen Variable stenosis secondary Stenosis secondary to loss of height to osteoarthritic changes and pseudo disc bulging Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

128 F. Ruiz Santiago et al

Figure 12 Ankylosing spondylitis. A) Sagittal STIR sequence shows edema of the vertebral margins and costovertebral joint (arrows). B) Coronal STIR image shows areas of edema in the sacroiliac joint (arrows). C) CT scan demonstrates subchondral erosions and sclerosis. D) Late stage with sacroiliac fusion. Diffuse idiopathic skeletal hyperostosis. Sagittal CT (E) shows the coarse prevertebral ossifi cations (arrows) and sagittal STIR MRI (F) demonstrate edema in the anterior aspect of the vertebral bodies (arrows).

Vertebral infection initial involvement of the disc space in relation to the vertebral body, resulting in more vertebral deformity and MRI is the most sensitive and specific tecnique for the larger paravertebral masses with neurologic deficit. 74 diagnosis of demonstrating decreased signal Isolated involvement of the vertebral body or posterior intensity in the disc and and endplates on T1-weighted elements may be diffi cult to distinguish from a tumor. 75 images. After contrast administration, the inflammatory The differential diagnosis includes intervertebral areas enhance while abscess areas remain hypointense (ring osteochondrosis in type I Modic changes, fractures in block enhancement). On STIR and T2 sequences, the involved vertebrae present in seronegative spondyloarthropathies, areas appear hyperintense. The degree of destruction of the neuropathic and chronic hemodialysis. 74 endplates depends on the progression of the disease and Laboratory tests including white blood cell count, ESR and extension into the soft tissues is variable 73 (fi g. 16). C-reactive protein allow for confi rmation of the infection. Findings of pyogenic spondylodiscitis may be However, guided biopsy may be needed to isolate the indistinguishable from those of tuberculous spondylodiscitis. etiologic pathogen, particularly when blood cultures yield However, the latter has a longer clinical course, with less negative results. Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies 129

Figure 13 Osteoid osteoma. A) STIR MRI shows hyperintense edema (arrow). B) Sagittal CT scan shows a small lytic lesion (arrow). C) Coronal CT. Osteochondroma. D) Sagittal T2 MRI. Giant cell tumor in the spinous process.

Figure 14 A) and B) Atypical vertebral hemangioma, with hyperintensity on T1 and STIR. B) and C) Typical vertebral hemangioma, with hyperintensity on T1 and hypointensity on STIR. E) and F) Hemangioma on CT. Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

130 F. Ruiz Santiago et al

Figure 15 A) Coronal CT. Chordoma with paravertebral extension (arrow). B) Axial CT. Ewing’s sarcoma of the right sacral wing (arrow). C) Axial contrast-enhanced T1 MRI. Mass in the vertebral body and vertebral arch secondary to myeloma. D) Sagittal T1 MRI. Hypointense lesions secondary to lymphoma (arrows).

Figure 16 Spondylodiscitis. Unenhanced sagittal (A) and contrast-enhanced (B) T1 images, STIR (C) show pyogenic infection with edema pattern and epidural abscess (arrow). D) CT scan shows destruction of endplates in a different patient with . E) and F) Sagittal T1 MRI (E) and sagittal CT (F) show endplate destruction in erosive intervertebral osteochondrosis secondary to degenerative listhesis. Presence of intradiscal air helped in the diagnosis. Documento descargado de http://www.elsevier.es el 02/11/2012. Copia para uso personal, se prohíbe la transmisión de este documento por cualquier medio o formato.

Computed tomography and magnetic resonance imaging for painful spinal column: contributions and controversies 131

Conclusion 4. West ATH, Marshall TJ, Bearcroft PW. CT of the musculoskeletal system: What is Left in the days of MRI? Eur Radiol. In this paper, we reviewed the main CT and MRI 2009;19:152-64. manifestations of the most common causes of spinal pain. 5. Antevil JL, Sise MJ, Sack DI, Kidder B, Hopper A, Brown CV, et al. Spiral computed tomography for the initial evaluation of An adequate clinical approach, an expert understanding of spine trauma: a new standard of care? J Trauma. 2006;61: the pathological manifestations demonstrated by these 382-7. imaging techniques and a comprehensive report based on a 6. Mulkens TH, Marchal P, Daineffe S, Salgado R, Bellinck P, te universally accepted nomenclature represent the Rijdt B, et al. Comparison of low-dose with standard-dose indispensable tools to improve the diagnostic approach and multidetector CT in cervical spine trauma. AJNR Am J the decission making process in patients with spinal pain. Neuroradiol. 2007;28:1444-50. The superior soft tissue characterization of RMI may be 7. Vertinsky T, Krasnokutsky MV, Augustin M, Bammer R. Cutting complemented with the high-resolution of CT for evaluating edge imaging of the spine. Neuroimaging Clin N Am. 2007;17: bone, although it exposes the patient to ionizing radiation. 117-36. 8. Bartynski WS, Petropoulou KA. The MR imaging features and clinical correlates in low back pain-related syndromes. Magn Autorship Reson Imaging Clin N Am. 2007;15:137-54. 9. Jarvik JG, Deyo RA. Diagnostic evaluation of low back pain with 1. Responsible for the integrity of the study: Fernando emphasis on imaging. Ann Intern Med. 2002;137:586-97. Ruiz Santiago 10. Kjaer P, Leboeuf-Y de CH, Korsholm L, Sorensen JS, Bendix T. 2. Conception of the study: Fernando Ruiz Santiago, María Magnetic resonance imaging and low back pain in adults: a diagnostic imaging study of 40-year-old men and women. Spine. del Mar Castellano García, Luis Guzmán Álvarez. 2005;30:1173-80. 3. Design of the study: Fernando Ruiz Santiago, María del 11. Weishaupt D, Zanetti M, Hodler J, Hodler J, Boos N. MR imaging Mar Castellano García, Luis Guzmán Álvarez, Manuel of the lumbar spine: Prevalence of intervertebral disk extrusion Tello Moreno. and sequestration, nerve root compression, end plate 4. Acquisiton of data: Fernando Ruiz Santiago, María del abnormalities, and osteoarthritis of the facet joints in Mar Castellano García, Luis Guzmán Álvarez, Manuel asymptomatic volunteers. Radiology. 1998;209:661-6. Tello Moreno. 12. Kalichman L, Ling L, Kim DH, Guermazi A, Berkin V, O’Donnell 5. Analysis and interpretation of data: Fernando Ruiz CJ, et al. Facet joint osteoarthritis and low back pain in the Santiago, María del Mar Castellano García, Luis Guzmán community-based population. Spine. 2008;33:2560-5. Álvarez, Manuel Tello Moreno. 13. Walker BF, Williamson OD. Mechanical or infl ammatory low back pain. What are the potential signs and symptoms? Manual 6. Statistical analysis: not applicable. Therapy. 2009;14:314-20. 7. Bibliographic search: Fernando Ruiz Santiago, María del 14. Kinkade S. Evaluation and treatment of acute low back pain. Mar Castellano García, Luis Guzmán Álvarez, Manuel American Family Physician. 2007;75:1181-8. Tello Moreno. 15. Meleger A, Krivickas L. Neck and back pain: musculoskeletal 8. Drafting of the paper: Fernando Ruiz Santiago, María disorders. Neurol Clin. 2007;25:419-38. del Mar Castellano García, Luis Guzmán Álvarez, Manuel 16. Bierry G, Kremer S, Kellner F, Abu Eid M, Bogorin A, Dietemann Tello Moreno. JL, et al. Disorders of paravertebral lumbar muscles: from 9. Critical review with intellectually relevant pathology to crosssectional imaging. Skeletal Radiol. 2008;37: contributions: Fernando Ruiz Santiago, María del Mar 967-77. Castellano García, Luis Guzmán Álvarez, Manuel Tello 17. Zmurko MG, Tannoury TY, Tannoury CA, Anderson G. Cervical sprains, disc herniations, minor fractures, and other cervical Moreno. injuries in the athlete. Clin Sports Med. 2003;22:513-21. 10. Approval of the fi nal version: Fernando Ruiz Santiago, 18. Leone A, Aulisa L, Tamburrelli F, Lupparelli S, Tartaglione T. The María del Mar Castellano García, Luis Guzmán Álvarez, role of computed tomography and magnetic resonance in Manuel Tello Moreno. assessing degenerative arthropathy of the lumbar articular facets. Radiol Med Torino. 1994;88:547-52. 19. Rihn JA, Lee JY, Khan M, Ulibarri JA, Tannoury C, Donaldson WF, Confl ict of interest et al. Does lumbar facet fl uid detected on magnetic resonance Imaging correlate with radiographic instability in patients with The authors declare no confl ict of interest. degenerative lumbar disease? Spine. 2007;32:1555-60. 20. Friedrich KM, Nemec S, Peloschek P, Pinker K, Weber M, Trattnig S, et al. The prevalence of lumbar facet joint edema in patients with low back pain. Skeletal Radiol. 2007;36:755-60. 21. Lakadamyali H, Tarhan NC, Ergun T, Cakir B, Agildere AM. STIR References Sequence for Depiction of Degenerative Changes in Posterior Stabilizing Elements in Patients with Lower Back Pain. AJR Am J 1. Medicare Part B Imaging Services. Rapid spending growth and Roentgenol. 2008;191:973-9. shift to physician offi ces indicate need for CMS to consider 22. Doyle AJ, Merrilees M. Synovial cysts of the lumbar facet joints additional management practices. Washington: U.S. in a symptomatic population: prevalence on magnetic Government Accountability Offi ce; 2008. resonance imaging. Spine. 2004;29:874-8. 2. Fu R, Carrino JA, Deyo RA. Imaging strategies for low-back pain: 23. Stoodley MA, Jones NR, Scott G. Cervical and thoracic systematic review and meta-analysis. Lancet. 2009;373: juxtafacet cysts causing neurologic defi cits. Spine. 2000;25: 463-72. 970-3. 3. Lurie JD, Birkmeyer NJ, Weinstein JN. Rates of advanced spinal 24. Fardon D, Millette P. 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