Imaging in Low back pain

F. Rajabzadeh, MD
Assistant professor of radiology
IAU, Mashhad

August,2020
• Low back pain is 5th most common reason for all
physician visits. Imaging of the lower spine
before six weeks does not improve outcomes, but
does increase costs.
• Don't do imaging for low back pain within
the first 6 weeks, unless red flags are
present.
• Most patients with radicular symptoms will
recover within several weeks of onset.
• The majority of disc herniations will regress or
reabsorb within eight weeks of onset.
• In the absence of progressive neurologic deficits
or other red flags, there is strong evidence to
avoid CT/MRI imaging in patients with non-
specific low back pain
• Studies have shown that patients with no back
pain often show anatomic abnormalities on
imaging.
• Risks associated with routine imaging include
unnecessary radiation exposure and patient
labeling. The labeling phenomenon of patients
with low back pain has been studied and shown
to worsen patients’ sense of well-being.
Red Flags
• Severe or progressive neurologic deficits (e.g.,
bowel or bladder function, saddle parasthesia)
• Fever
• Sudden back pain with spinal tenderness
(especially with history of osteoporosis, cancer,
steroid use)
• Trauma
• Serious underlying medical condition (cancer)
• Weight loss, immunosuppresion, IV drug abuse,
>70 yo, significant trauma
• The choice of certain radiological method over
other depends on many factors like patient’s
presentation, presence of contraindication,
availability, relative cost of the test, and the
expected impact of the results on management.
• Radiological evaluation helps the physician
reach the most likely cause of LBP, confirm the
provisional diagnosis, provide alternative one, or
narrow the differential diagnosis.
• Plain X-ray radiograph is useful in initial general
assessment.
• Magnetic resonance imaging (MRI) is the
imaging modality of choice in the evaluation of
LBP because of elegant demonstration of
anatomical details and many pathologies.
• Computerized tomography (CT) can provide
high-resolution images of the bonystructures
and is particularly invaluable in trauma.
• sonography may have a role in the evaluation of soft
tissue lesions and the sacroiliac joints.
• Angiography is useful for vascular evaluation.
Isotope imaging may be used in the elucidation of
hidden cause of pain (tumors or fracture).
• Conventional myelography and discography are
virtually obsolete in current clinical practice because
of the presence of much safer and accurate new
modalities.
• Finally, interventional radiology has an increasing
role in treating certain conditions.
Plain X-ray radiograph

Advantages
• Low cost
• Availability
• Noninvasiveness
• Acceptable resolution of bony structures
• No significant contraindication
Plain X-ray radiograph
limitations
• Poor visualization of soft tissue structures.
• Cannot show the details of the spinal canal.
• Cannot show the intervertebral disc material and
hence will not give information about the type nor
the severity of herniation [3]. Factors like obesity
and excessive bowel gases may obscure some
abnormalities or make interpretation of
X-ray difficult.
• Source of radiation to the patient.
X-ray Dx value
• General alignment of the spine, any asymmetry, or
gross deformity. Straightening
of the normal lumbosacral curvature may be
considered as an indirect sign of acute spasm or
pain.
• Abnormal position of certain vertebra in the form of
foreword (spondylolisthesis)or backward
(retrolisthesis) shifting of the vertebral body relative
to the vertebrae above and below.
• Some congenital anomalies of the spine like
scoliosis, spina bifida, and vertebral deformities
in the form of abnormal shape, number, and
alignment.
• Lumbosacral spinal degenerative changes in the
form of disc space narrowing, marginal
osteophytes and bony sclerosis near disc
• Signs of spinal inflammations
• Bone tumors
Magnetic resonance imaging
Advantages
• No radiation
• Noninvasiveness
• Excellent imaging quality of the spine and pelvis
• Most accurate modality in the demonstration of
the neural structures that can be the source of
LBP like the spinal cord and nerve roots
Limitations
• Presence of contraindications (see Section 3.5).
• Imaging quality is affected by the patient’s motion, so examination needs a
cooperative and stable patient. Agitated and unstable patients result in bad
images that are diagnostically not useful.
• Long examination time, usually 10-20 minutes (longer than X-ray and CT)
• Not so accurate in certain conditions like cortical fractures and
calcification(CT scan and lesser extent X-ray radiography are better).
• Clinical MRI mismatch. Many abnormal findings specially disc
degeneration or mild herniation are seen incidentally on spinal MRI of
asymptomatic persons and vice versa where MRI can be completely normal
in the presence of significant LBP. This has raised the issue of importance of
clinical and electrophysiological correlation and the controversial need for
more specific diagnostic tests like discography
Contraindications
• Cardiac pacemakers, cochlear implants
• Metallic object (shells, bullet, orthopedic fixation devices). However, if the
fixation devices used were made of MRI-compatible metals (more
expensive than regular ones), MRI examination can be safely done despite
some artifacts that slightly reduce diagnostic imaging quality.
• Early pregnancy. However, the chemical material sometimes may be
injected intravenously (gadolinium) to enhance the images, and this should
not be used throughout pregnancy.
• Claustrophobia. Seen in about 5–10% of population, when the person is
unwillingly afraid of being in closed space. This problem may be resolved by
reassurance and careful description of the procedure to the patient.
Sometimes the patient will need to be examined using a special type of MRI
device called “open type” that has wider aperture and more space around
the patient. Rarely sedative/antianxiety drugs may be prescribed.
MRI Dx value
• Comprehensive evaluation of the lower back ,Variable
pathologies from degenerative,neoplastic, infective, and
congenital abnormalities can be elegantly demonstrated.
• Complete evaluation of the spinal canal including the
presence of any narrowing, stenosis or abnormal widening.
Measurement of the cross-sectional areaof the canal is
preferred to objectively assess stenosis.
• Detection of any mass within or outside the spinal canal that
may have effects on the spinal cord, nerve roots, soft tissues,
or bones including vertebral bony tumors, nerve sheath
tumors, lipomas, vascular malformations,etc. [6].
• Accurate depiction of variable congenital spinal
malformations that may present as LBP, like scoliosis, spina
bifida, myelomeningocele, dermoids, splitting of the cord,
low-lying tethered spinal cord, and absence of the sacrum.
CT
Advantages
• Excellent depiction of the bony anatomy and bony changes at
the lower back including lumbosacral spine and pelvis [7].
Bony changes can be readily seen on CT even before
appearance on X-ray radiographs.
• Can compete with MRI in the visualization of lumbar disc
prolapse and bony spinal canal stenosis.
• Relatively more widely available and accessible than MRI.
• Lesser cost than MRI.
• Less affected by the patient’s motion during examination than
MRI.
• Short time of examination (usually less than minute).
• Can be safely done for patients with metallic implants, shells,
and magnetic fixation devices (but some image compromise).
CT
• Limitations
• High risk of radiation exposure [7]. This is indeed
the most important disadvantage of CT scan. CT
scan delivers a huge amount of radiation dose to the
patient (almost 100 times that of chest X-ray).
• Poor demonstration of intraspinal neural content
like cord and nerve root andearly bone marrow
infiltration
• Artifacts from metallic fixation devices or shells
may badly affect the quality of image and can
obscure some anatomical and pathological findings.
CT Dx value
• Abnormal bone densities of the lower spine and pelvis including osteolytic (blacker) and
osteoblastic (whiter) lesions, with a lot of possible causes, from incidental nonsignificant
(bone islands), benign (hemangiomas, osteomas) to malignant (metastases, multiple
myeloma) lesions.
• Abnormal configuration and deformity, whether of congenital origin or as sequel of old
trauma or surgery.
• Traumatic findings like linear fracture, partial or complete vertebral compression, and
burst vertebra (Figure 3). CT scan can detect even tiny fractures of the bony cortex
particularly of the posterior spinal elements (laminae and pedicles) which are usually
difficult to be seen and may be missed on X-ray radiographs [3].
• Size, shape, and exact location of the metallic foreign body or shell or bullet.
• Bone erosion secondary to inflammation, infection, or tumor.
• Many (but not all) features of spinal degeneration like intervertebral disc space narrowing,
marginal osteophytes, and facet joints sclerosis.
• Calcification. CT scan is the best imaging modality in defecting calcification in paraspinal
soft tissues, ligaments, muscles, or within a mass. The presence of calcification has
important diagnostic impact as it helps narrow the differential diagnostic list or may reach
final diagnosis like hydatid cyst or para-articular calcification in some chronic
arthropathies.
L5-S1 disk extrusion in a 42-yearold
man with left-sided sciatica. (a) Sagittal,
nonenhanced, dual-echo MR image shows a
large extruded fragment (arrow) migrating
inferiorly from the L5-S1 intervertebral
space. Note the defect of the annulus,
the low-signal-intensity margin of the disk at
the normal levels. Note also the similarity
between the signal intensity within the
extruded fragment and that of the parent disk,
which is indicative of acuity. (b) Transverse
nonenhancedT1-weighted MR image (400/15)
shows the large extruded fragment (arrows)
displacing the transiting S1 nerve against the
posterior lamina of the S1 vertebral body. The
fragment is apparently effacing the nerve sleeve.
Relatively little thecal sac compromise is seen
owing to the capacious canal at this level.
Diskitis and paraspinous abscess in a 17-year-
old boy with unrelenting low back pain
that awakened him at night and low-grade
fever at physical examination. (a) Sagittal,
nonenhanced,T2-weighted MR shows increased
signal intensity of the vertebral bodies
immediately adjacent to the L1-2
intervertebral space. A more diffuse signal
intensity increase throughout the L2 vertebral
body also is seen. Note that the disk itself has
relatively low signal intensity except
immediately at the site of the end plate signal
intensity alteration. (b) Corresponding sagittal,
contrast material–enhanced, T1-weighted MR
image shows enhancement of the abnormal
end plates. Slight enhancement of the parent
disk also is seen. (c) Transverse, postcontrast,
T1-weighted MR image obtained at the level
of the intervertebral space shows enhancing
tissue extending from the intervertebral
space into the right neural foramen (arrow).
(d) Transverse, postcontrast, T2-weighted MR
image obtained at a lower level shows myositis
and a small focal abscess (arrow) within the
psoas muscle
L1-2 disk extrusion and migration
in a 52-year-old man with right groin pain.
(a) Transverse nonenhanced CT scan shows a
vague abnormality (arrows) of the right half of
the canal, with a suggestion of high attenuation.
This finding is relatively nonspecific.
(b) Sagittal contiguous nonenhanced T2-weighted
MR images show a soft-tissue mass
(arrows) consistent with extrusion of disk
material(particularly on the off midline image,
where the contiguity of the material with the
parent disk is shown). The fact that the mass is
centered at the parent disk intervertebral space
and the contiguity of the mass with the parent
disk, as opposed to the nonspecific masslike
appearance at CT (a), strongly support disk
extrusion. Varying degrees of disk degeneration
and protrusion are seen at the lower four
levels.
Grade IV spondylolisthesis in a 17-year-old boy with chronic low back pain and no
neurologic dysfunction.
Transverse, nonenhanced, T2-weighted MR image (3,500/98) obtained in a 58-year-old woman with
postoperative pain shows postoperative spinal fluid leakage. The fluid collection (arrows) is
emanating from the spinal canal posteriorly. The high signal intensity of the fluid, its indentation of
the thecal sac, as well as its location, are all consistent with cerebrospinal fluid leakage.
Arachnoiditis in a 52-year-old woman with
postoperative back pain. (a) Sagittal, postcontrast, T1-
weighted image (450/10) shows enhancement of the
cauda equina nerve roots (arrows) and their
adherence to the posterior surgical site. (b) Transverse,
postcontrast, T1- weighted MR image (800/13) shows
clumping (arrow) of the nerve roots at the L3-4 level.
The findings of adhesion and enhancement represent
changes of arachnoiditis.
A 59-year-old male presented with progressive bilateral lower extremity weakness,
cough, and malaise Sagittal T1 fat, saturated magnetic resonance imaging of the
lumbar spine demonstrates thin micronodular enhancement of the surface of the
spinal cord. Further patient workup revealed metastatic lung cancer.
A 68-year-old male presented with severe low back pain and altered bilateral lower
extremity sensation after falling down. He was taking Plavix for a coronary stent.
A sagittal T1 weighted magnetic resonance imaging of the lumbar spine demonstrates
an anterior epidural hematoma from T12 through L5 (black arrow).
A 28-year-old male was imaged because of progressive worsening low back pain. A Sagittal short tau
inversion recovery magnetic resonance imaging of the lumbar spine demonstrates Romanus lesions,
also known as “shiny corners” at the anterior superior endplates of L3 and L4 (white arrows).
Further workup revealed a diagnosis of ankylosing spondylitis .
Transverse nonenhanced MR image (800/13) of the spine at the L4 level obtained in a
32-year-old woman following fusion shows pedicle screw (titanium) artifact (two-sided
arrow). Despite the artifact, the central canal is well delineated.
Scheuermann kyphosis in a 14-year-old boy. Sagittal T2-weighted image demonstrates
thoracic kyphosis with mild anterior wedging of the T10 –T12 vertebral bodies with
slight disk space irregularity and Schmorl nodes. Minimal annular bulges slightly indent the
ventral aspect of the thecal sac.
Vertebral osteomyelitis and diskitis in a 7-year-old boy. A, Sagittal T2-weighted image with fat
saturation shows marked disk space narrowing at L2–L3 with hypointense T2 signal intensity within
the disk. There is increased T2 prolongation in adjacent vertebral bodies. B, Sagittal T1-weighted
MR image with fat saturation with gadolinium shows diffuse enhancement in the L2–L3 vertebral
bodies and intervening disk space.
Osteoid osteoma in a 14-year-old girl
Osteoblastoma in a 12-year-old boy. A, Axial CT image demonstrates an
expansile lytic lesion in the pedicle of the C5 vertebra, which involves the
C4–C5 facet joint and the left transverse foramen. B, Axial T1-weighted
image with gadolinium and fat saturation demonstrates extensive
enhancement in the adjacent bone and the left paraspinal soft tissues of the
cervical spine, with extension into the epidural space.
LCH vertebra plana in an 18-month-old boy. A, Sagittal 2D CT reconstruction image of
the lumbar spine shows a collapsed L3 vertebral body. B, Sagittal T2-weighted MR
image of the lumbar spine demonstrates a vertebra plana deformity with significant
decreased height of the L3 vertebral body and preservation of the adjacent
intervertebral disks.
Lymphoblastic lymphoma in a 15-year-old boy. Sagittal T2-weighted MR image
demonstrates an intraspinal extradural well-circumscribed hypointense lesion at the
T2–T4
level with compression of the spinal cord with hypointensity diffusely in the vertebral
bodies.
Acute lymphoblastic leukemia in a 3-year-old boy. A, Sagittal T1-weighted MR image demonstrates
diffuse abnormal low signal intensity in the lumbar spine bone marrow consistent with a diffuse
infiltrative process. B, Sagittal T1-weighted image of a healthy 3-year-old boy with normal higher
T1 signal intensity of the vertebral body marrow relative to the intervertebral disks.
Ewing sarcoma of the lumbar spine in a 17-year-old boy. A, Post-contrast-enhanced
axial CT image demonstrates a large partially calcified mass in the paraspinal
musculature
at the L3–L5 levels. The mass involves the adjacent spinous process and extends into
the spinal canal. B, Axial T1-weighted postgadolinium MR image shows extensive
enhancement of
the mass with epidural extension
Astrocytoma in an 11-year-old boy. A, Sagittal T2 MR image of the cervical and upper thoracic
spine demonstrates a partly cystic and solid intramedullary spinal cord tumor. B, Sagittal T2 MR
image of the thoracic spine demonstrates a partly cystic and solid intramedullary spinal cord tumor.
C, Sagittal T1-weighted postcontrast MR image shows enhancement of the solid portions of the
tumor and peripheral enhancement of the cystic components.
Myxopapillary ependymoma in a 12-year-old boy. Sagittal T1-weighted postcontrast
MR image demonstrates an intradural extramedullary mass lesion extending from the
T12
to L3 levels and a second lesion at the L5–S2 level with diffuse enhancement. There is
associated scalloping of the posterior aspects of the lumbar vertebral bodies.
Focal form of spinal brucellosis in a 26-year-old woman with systemic
brucellosis and low back pain, showing loss of disk height between
L4-L5 Fat-suppressed T1-weighted magnetic resonance image after
administration of gadolinium, showing focal enhancement of the
anterior aspect of the superior end plate of L4 and L5
A 44-year-old woman with lower back pain that radiated to the left side and a positive Brucella titer. (A) Plain
radiograph, showing widening of the left sacroiliac (SI) joint with erosions and sclerosis on the iliac side (arrow). (B)
CT, elegantly demonstrating widening of the left SI joint, with erosions and sclerosis on the iliac side (arrow). (C)
Axial T1-weighted image, showing low signal on both sides of the SI joint along with widening (arrow). (D) Axial T1
post gadolinium infusion, showing avid enhancement of the SI joint, bone, and muscles consistent with brucellar
septic arthritis and osteomyelitis (arrow).
differentiating brucellar spondylitis
from tuberculo-spondylitis
• involvement of the multiple vertebral bodies
with the involvement of the disk space and
Gibbus deformity usually suggests tuberculo-
spondylitis