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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6012_Библиотеки_им_академика_М_И_Перельмана.pdf
Chapter 13 Spine Imaging 223
CD
SECTION
II
AB
FIG. 13.28 Follow-up imaging is valuable when evaluating lesion behavior over time. (A) Sagittal T2-weighted
magnetic resonance image and (B) sagittal T1-weighted contrast-enhanced image demonstrate cord signal
abnormality and enhancement (arrow). Follow-up imaging obtained 1 year later demonstrates (C) progression
of T2 signal abnormality (arrow) and (D) resolution of the enhancement. Findings are consistent with
demyelination.
A
FIG. 13.29 Ependymoma. (A) Sagittal T1-weighted magnetic resonance image shows large cystic and solid
intramedullary mass within the cervical cord. A tumor-associated cyst extends to the medulla. (B) Sagittal
T2-weighted image shows central solid component (arrow) with cephalad and caudad cystic components. (C)
Sagittal T1-weighted image after contrast administration shows large enhancing solid component extending
down to C5–C6 (black arrows).
B
C
224 DIAGNOSIS
improvements in brain and cord lesion burden with changes
in clinical disability scoring. Most focal plaques are less than
two vertebral body lengths in size, occupy less than half the
cross-sectional diameter of the cord, and are characteristically peripherally located with respect to a transverse, crosssectional reference. Of spinal cord multiple sclerosis lesions,
60% to 75% are present in the cervical region, and more than
FIG. 13.30 Ependymoma in a patient with neurobromatosis type 2.
Sagittal T1-weighted magnetic resonance image after contrast
administration shows multiple intradural extramedullary enhancing masses
(schwannomas or meningiomas), combined with a less intensely enhancing
mass within the conus (ependymoma).
half of multiple sclerosis patients with cord plaques have
multiple plaques. Of patients with cord plaques, 90% have
intracranial multiple sclerosis plaques.
200,219,220
Intradural Extramedullary Lesions
Intradural extramedullary neoplasms constitute the largest
single group of primary spine neoplasms, accounting for
approximately 55% of all primary spine tumors. Most of these
tumors are benign, with nerve sheath tumors and meningiomas
representing the most common lesions.
are the most common intraspinal tumors and are divided
histologically into two types: schwannomas (i.e., neuromas,
neurinomas, and neurilemmomas) and neurobromas (Fig.
13.33). Solitary schwannomas constitute most intraspinal
nerve sheath tumors, whereas neurobromas are almost
always associated with neurobromatosis type 1. Patients with
neurobromatosis type 2 more commonly have multiple
schwannomas rather than neurobromas, however.
nerve sheath tumors can arise anywhere in the spine.
Nerve sheath tumors are easily recognized on MRI as typically isolated, well-circumscribed, solid masses of so tissue
signal intensity on T1-weighted images surrounded by low
signal CSF. On T2-weighted images, they are of variable signal
intensity. Schwannomas are more vascular and include cystic
degeneration, necrosis, and hemorrhage more commonly
than neurobromas. Various local osseous changes, consisting
mainly of smooth bony remodeling or foraminal enlargement,
are common. Enhancement is almost always present, but the
pattern is variable.
Meningiomas most commonly occur in the thoracic
223
spine.
As is the case intracranially, there is a female sex
predilection, and these lesions occur in a slightly older age
group than nerve sheath tumors. Most are entirely intradural
and typically are isointense to the neural elements on T1- and
218
Nerve sheath tumors
221
Isolated
222
A
FIG. 13.31 Cavernous angioma. (A) Sagittal T1-weighted magnetic resonance image shows linear focus of
high signal reecting hemorrhage within the cord at C2 level. (B) Axial gradient-echo image conrms blood as
focal low signal within substance of cord. (C) Axial gradient-echo image through the brain shows multiple areas
of low signal (dark spots) reecting hemosiderin deposition owing to multiple cavernous angiomas.
B
C
Chapter 13 Spine Imaging 225
SECTION
II
A
FIG. 13.32 Short-tau inversion recovery imaging for intramedullary inammatory disease. (A) Sagittal and (B)
axial images show multiple foci of abnormal increased signal throughout the cervical cord without expansion,
reecting demyelinating disease (arrows).
B
AB
FIG. 13.33 Schwannoma. (A) Sagittal T1-weighted, (B) T2-weighted, and (C) T1-weighted enhanced magnetic
resonance images show a round, intensely enhancing intradural mass at the L4 level, displacing the adjacent
cauda equina.
C
T2-weighted images. Meningiomas enhance intensely aer
gadolinium–diethylenetetramine-pentaacetic acid (DTPA)
administration, which may allow demonstration of the typical
broad dural base.
224,225
e last category of intradural extramedullary lesions is
the so-called leptomeningeal pattern, which includes leptomeningeal metastatic disease, inammation, and benign
granulomatous processes such as sarcoid and tuberculosis
(Fig. 13.34).
226
e list of tumors that may seed the CSF is
long, but the most common types are cranial ependymomas,
glioblastomas, and medulloblastomas (especially in pediatric
patients). Additional malignancies that can spread less commonly are ependymoma, pineoblastoma, germinoma, and
retinoblastoma. Lesions outside the central nervous system
that are capable of spreading along the leptomeninges include
carcinoma of the lung and breast, lymphoma, leukemia,
and melanoma. Administration of contrast material with
T1-weighted images is mandatory and shows a linear and
nodular enhancement pattern along the leptomeninges. e
overall sensitivity of MRI examinations is low in patients with
226 DIAGNOSIS
A
FIG. 13.34 Leptomeningeal enhancement. Sagittal T1-weighted magnetic
resonance images (A) before and (B) after contrast administration show
extensive leptomeningeal enhancement of cauda equina and distal cord
surface in a patient with Staphylococcus aureus meningitis.
B
A B
FIG. 13.35 In general, most pathologic marrow (neoplastic, degenerative,
or infectious) demonstrates water signal intensity. However, distribution of
the signal abnormality can be helpful in arriving at a dierential diagnosis.
(A) Sagittal T1-weighted image and (B) sagittal short-tau inversion recovery
(STIR) image demonstrates abnormal low T1 signal intensity and STIR
hyperintensity centered about the C2–C3 facet joint (arrow), which is
degenerative or inammatory in nature rather than neoplastic.
proven histologic evidence of neoplastic seeding, so examination of the CSF remains the gold standard.
Extradural Lesions
Pathology that can involve the extradural space can include
degenerative disc disease, epidural hematoma or abscess, or
neoplasm extending from adjacent osseous structures.
Bone Marrow Imaging
MR imaging is the preferred modality for imaging the bone
marrow when compared with radiographs or CT imaging,
although CT imaging can demonstrate osseous destruction or
abnormal increased attenuation. Pathologic or abnormal
marrow on MR imaging is typically manifested as low T1
signal intensity and T2 or STIR hyperintensity. Distribution
of the marrow abnormalities is helpful, as abnormal marrow
centered about a joint or articulating surface can be degenerative or inammatory in nature rather than neoplastic (Fig.
13.35). Complete marrow replacement by low T1 signal
intensity can be seen with both metastatic disease and red
marrow replacement in patients with anemia.
can demonstrate the matrix of a lesion (increased attenuation
when osteogenic, ground glass for brous lesions, or anular
calcications in cartilaginous lesions). Lesions with sclerotic
borders tend to be less aggressive compared with lesions with
ill-dened or poor margins.
229
Primary and secondary tumors to the extradural space are
well evaluated by MRI and CT (Fig. 13.36). Metastatic disease
228
227
CT imaging
to the spine is the most common type of extradural tumor.
Because of its high contrast sensitivity and spatial resolution,
MRI is the examination of choice in the detection of osseous
metastases (Figs. 13.37 and 13.38).
230,231
Because many metastatic tumors enhance, the routine use of contrast medium–
enhanced studies alone is not recommended because the
distinction between metastases and normal marrow fat is
diminished, occasionally to the point of masking even large
lesions (Fig. 13.39). Although diuse osseous metastases can
appear as homogeneous, diuse, low marrow signal on
T1-weighted images, this appearance is not specic.
Ossication of Posterior Longitudinal Ligament
Ossication of the posterior longitudinal ligament (OPLL)
begins with calcication followed by frank ossication of the
posterior longitudinal ligament in the upper cervical spine
(C3–C4 or C4–C5). It may progress inferiorly to the upper
thoracic spine (Figs. 13.40 and 13.41).
present in the sixth decade of life, are generally older than
typical patients with disc disease, and are younger than
patients with cervical spondylosis. Presenting complaints
include neck pain, dysesthesias, and upper and lower extremity weakness. CT ndings oen show the bony pathology
better than MRI. Hirabayashi and Satomi
into four types based on CT: (1) continuous OPLL extends
between vertebral bodies and crosses multiple disc spaces
(27% of cases), (2) segmental OPLL is limited to the posterior
vertebral body margins (39% of cases), (3) mixed OPLL is
continuous and segmental (29% of cases), and (4) the remaining 5% of OPLL is restricted to the disc space level.
232
Patients tend to
233
divided OPLL
Chapter 13 Spine Imaging 227
SECTION
II
A
FIG. 13.36 Chondroblastic osteosarcoma. (A) Sagittal T2-weighted magnetic resonance image shows large
paraspinal mass with well-dened margins and heterogeneous internal signal typical of cartilaginous lesions,
including chordoma. (B) Axial T1-weighted image after contrast administration shows a large, irregularly
enhancing mass involving the left lateral aspect of the thoracic body with extension into the paravertebral
region. There is left lateral epidural extension of tumor with mild mass eect on the cord.
A
FIG. 13.37 Multiple myeloma. (A) Sagittal T1-weighted magnetic resonance
image shows markedly diminished signal from all the visualized marrow of
thoracolumbar spine. There is severe compression deformity at L1. (B)
Sagittal T2-weighted image shows typical “salt and pepper” pattern of
multiple myeloma. No epidural tumor is identied.
B
B
Spinal Cysts
Various investigators,
234-236
including Nabors and colleagues,
have claried the confusing array of terms for spinal menin-
geal cysts. Spinal meningeal cysts are congenital diverticula of
the dural sac, root sheaths, or arachnoid that may be classied
into three major groups. e rst group includes extradural
cysts without spinal nerve roots (type I), the second includes
extradural cysts with spinal nerve roots (type II), and the third
includes intradural cysts (type III) (Fig. 13.42). Type I are
diverticula that maintain contact with the thecal sac by a
narrow ostium. Type I cysts include extradural cysts, pouches,
and diverticula and the so-called occult intrasacral meningo-
celes. Sacral type I cysts are found in adults and are connected
to the tip of the caudal thecal sac by a pedicle. Type II meningeal cysts with contained nerve roots are extradural lesions
previously called Tarlov cysts, perineural cysts, or nerve root
diverticula. ese are generally seen as multiple incidental
lesions but are occasionally associated with radiculopathy or
incontinence. Type III meningeal cysts are intradural lesions
most commonly found on the posterior subarachnoid space
and have been called arachnoid diverticula or arachnoid cysts.
ese are lined by a single layer of normal arachnoid cells and
lled with CSF.
235
Circumferential compression of the cord may result from
combined OPLL and ossication of the ligamentum avum.
In continuous OPLL, MRI shows a thick band of decreased
signal on T1- and T2-weighted images. e segmental type is
more dicult to discern on MRI and shows a thin area of
decreased signal intensity, without signal from within the
ossication region.
Trauma
Studies have shown that if strict criteria are followed, patients
who arrive at the emergency department with a collar in
place can be clinically evaluated as to whether plain lms are
required.
237,238
Patients with cervical fractures typically have
228 DIAGNOSIS
AB C
FIG. 13.38 Metastatic disease. (A) Lateral radiograph of the cervical spine demonstrates subtle cortical
irregularity (arrow), which is much more apparent on (B) computed tomographic and (C) magnetic resonance
imaging (arrows).
A
FIG. 13.39 Diuse metastatic disease. (A) Sagittal T1-weighted magnetic resonance image shows diuse
abnormal decreased marrow signal from L4 through L1 bodies. There is residual fatty marrow replacement
involving L5 and the sacrum from prior radiation therapy. There is mild anterior epidural extension of tumor at
L4. (B) T2-weighted image shows mass eect of epidural tumor but tends to minimize marrow signal
abnormality. (C) After contrast material is administered, T1-weighted image shows less marrow abnormality
owing to enhancing tumor mimicking fatty marrow signal.
B
C
Chapter 13 Spine Imaging 229
SECTION
II
A
B
D
at least one of the following: intoxication, neck tenderness,
altered level of consciousness, or a painful injury elsewhere.
Indications for CT in evaluation of the cervical spine include
further evaluation of known or questionable fracture on
plain lms and evaluation of areas inadequately seen on plain
239,240
lms.
Techniques vary from institution to institution, but
slice thickness is generally 1.5 to 2 mm, sagittal and coronal
reformats, so tissue and bone windows, with no intravenous
contrast material. e sensitivity of CT to detect fracture is 78%
to 100%.
241,242
CT is particularly useful in diagnosing posterior
element (laminar) fractures. e use of spiral thin-section
techniques (1 to 1.5 mm) with multiplanar reformats should
enable sensitivity approaching 100%. Most institutions use
CT as the primary screening study in patients with multiple
areas of trauma, bypassing plain lms.
243,244
When imaging the
cervical spine with radiographs, the average time to complete
the examination approaches 22 minutes as opposed to an
average time of 12 minutes with CT imaging.
245,246
Plain lms
C
FIG. 13.40 Ossication of posterior longitudinal ligament. (A) Sagittal
T1-weighted magnetic resonance image shows band of abnormal
mixed signal intensity spanning epidural space from C3–T1 (arrows),
with dorsal displacement of cord. (B) Mass eect is conrmed on
sagittal T2-weighted image, with owing anterior epidural mass
primarily showing low signal. Axial (C) gradient-echo and (D)
T1-weighted images show mass severely eacing cord.
with exion and extension can be of use in dening instability
in patients with persistent pain or so tissue swelling without
a denite fracture on the initial plain lm evaluation.
MRI allows direct visualization of cord abnormalities, which
cannot be identied by any other imaging modality. MRI can
dene intramedullary hematoma, intramedullary edema and
contusion, disc herniations, ligamentous injury, and epidural
hemorrhage (Fig. 13.43).
247-250
Hemorrhage within the rst
week is seen as low signal on T2-weighted images related to
deoxyhemoglobin. Contusion without hemorrhage is identied as high signal on T2-weighted images and as isointense or
decreased signal on T1-weighted images. Ligamentous disruption is seen as loss of the usual low signal from the anterior
and posterior longitudinal ligaments, with increased signal on
T2-weighted images in the adjacent tissues.
251,252
e most common area of traumatic involvement in the
lumbar spine is the thoracolumbar junction, which acts as a
fulcrum for spine motion and is susceptible to unstable
230 DIAGNOSIS
AB
C
FIG. 13.41 Thoracic ossication of posterior longitudinal ligament. (A) Axial computed tomographic (CT) scan
and (B) sagittal reformat show large owing bony mass encompassing the anterior epidural space throughout
the mid-thoracic spine. Sagittal (C) T1-weighted and (D) T2-weighted magnetic resonance (MR) images are
more dicult to interpret without CT guidance because the heterogeneous anterior epidural signal could
reect blood or fatty marrow (arrows). MR images do show the degree of mass eect on the thecal sac and
cord. (E) On axial gradient-echo image, the cord is atrophic and there is diuse hemosiderosis of the cord
surface seen as linear low signal (long arrow), with ossication of the posterior longitudinal ligament mass of
very low signal within anterior epidural space (short arrows). There are small bilateral pleural eusions.
DE
Chapter 13 Spine Imaging 231
SECTION
II
A
FIG. 13.42 Arachnoid cyst and syrinx. (A) Sagittal T1-weighted magnetic resonance image through the
thoracic spine shows a ventrally displaced cord with abruptly expanding dorsal margin at T4 level (arrow), with
a small syrinx seen as linear low signal within the cord. (B) Sagittal T2-weighted image shows a thin line of low
signal at the cephalad margin of the dorsally expanded cerebrospinal uid (CSF) space (arrow) with a
“windsock” pattern reecting an arachnoid cyst margin. (C) Single sagittal image from a cine CSF ow series is
encoded to show upward motion as dark areas. This technique outlines the abrupt change in CSF ow pattern
at the top of the cyst (arrow).
A
B
B
C
C
FIG. 13.43 Flexion dislocation fracture. (A) Sagittal and
(B) axial computed tomographic images of a patient
after motor vehicle trauma show C5 burst fracture with
posterior dislocation. There is a large sagittal fracture
component (short arrow) and bilateral facet fractures
and lamina fractures (long arrows). (C) Sagittal and (D)
axial T2-weighted magnetic resonance images show
severe cord compression by C5 retropulsed body
(arrow) with extensive prevertebral edema. (E) Sagittal
T2-weighted image after corpectomy and fusion shows
D
E
site of cord transection by C5 body (arrow) and
extensive cord edema.
232 DIAGNOSIS
A
FIG. 13.44 Subdural hemorrhage. (A) Sagittal and (B) axial T1-weighted magnetic resonance images show
high signal blood along dural margin from L3 to S1 (arrows). Axial image shows that the exterior margin of
blood is delimited by dura, so it must be either subarachnoid or subdural in location. Loculation on the axial
view is typical for a subdural location.
B
traumatic injury. e thick, sagittally oriented lumbar facets
minimize rotational injury, but exion and axial loading
injuries oen occur. e forces may combine to produce
exion-compression injuries or the so-called burst fracture.
Burst fractures are notable for instability and a predisposition
for displacing fracture fragments posteriorly and causing
spinal cord compression.
253,254
CT remains the method of
choice for the detection of retropulsed bony fragments and for
the demonstration of fractures of the posterior elements.
255
In
trauma patients when CT imaging of the chest, abdomen, and
pelvis is obtained, the existing image data set can be processed
to evaluate the spine, negating the need for additional image
acquisition and resultant radiation exposure.
256
A hyperexion injury occurring in the lumbar spine is the
seat belt or Chance fracture, which is associated with rapid
deceleration motor vehicle accidents. is type of trauma
produces a horizontal fracture through anterior and posterior
elements.
257,258
e anterior component may be through the
vertebral body or through the disc itself. Although CT is more
sensitive than MRI for detecting bony abnormalities, MRI is
oen superior for evaluating so tissue structures. In particular, the spinal ligaments show focal discontinuity on
T1-weighted images and areas of increased signal intensity on
T2-weighted images.
Hemorrhage
Epidural spinal hematomas occur most frequently in elderly
adults but can occur at any age.
tomas are broadly classied into two groups: nonspontaneous and spontaneous. Nonspontaneous epidural spinal
259-261
Epidural spinal hema-
hematomas may result from spinal taps, spinal anesthesia,
trauma, pregnancy, bleeding diathesis, anticoagulant therapy,
spinal hemangiomas, vascular malformations, hypertension,
and neoplasms. e history can oen be revealing, yet these
tumors commonly occur merely from an episode of sneezing, bending, voiding, turning in bed, or other mild trauma.
Epidural spinal hematomas can be localized or can spread
anywhere along the spinal column. Blood more commonly
accumulates posterolaterally.
Subdural hemorrhage is capable of producing severe and
irreversible neurologic decits, and acute surgical intervention may be needed. Spinal subdural hematomas can have a
typical conguration (Fig. 13.44A).
262,263
As opposed to epidural hematomas, which tend to be capped by fat, subdural
hematomas are located within the thecal sac and are separate
from the adjacent extradural fat, the vertebral bodies, and the
posterior elements. Axial images are useful in dening the
epidural fat surrounding the thecal sac as well as the blood
relating to the interior of the sac with subdural hematomas.
ese may be loculated anteriorly and posteriorly within the
thecal sac. e loculation can take the form of a “Mercedes
Benz sign,” showing a trefoil conguration (Fig. 13.44B).
KEY POINTS
1. Metal artifact on MRI can be reduced with use of FSE, larger
elds of view, higher readout bandwidths, smaller voxel sizes,
and appropriate geometric orientation of the
frequency-encoded direction in relationship to the metal.
2.
The most common spinal vascular lesion is the dural stula,
and the most sensitive MRI nding is increased signal on
T2-weighted images within the cord.