A
Carotid or Cerebral Angiogram is a diagnostic test designed
to show the condition of the blood vessels of the brain.
X-ray contrast material is injected into an artery through
a small tube (catheter), and X-ray images are obtained.
Carotid angiography is used to study the caliber of the carotid
artery and look for stenosis that may be significant and cause an increased risk
of stroke. Carotid angiography is performed with a routine angiographic procedure
from the groin using thin catheters. Often both the carotid artery in the neck
and the intracerebral vessels are studied at the same time.
Cervical spine biopsies can be performed with CT fluoroscopy. This is indicated for lesions of the cervical spine that are thought to be metastatic and if so, would change the management of the patient. With attention to details, the carotid artery, the esophagus and other vital structures in the neck can be avoided and good sample material can be obtained from the vertebral bodies with a low complication rate.
Biopsy of the cervical spine can be safely done with CT guidance. Image to the right is a case of hemangioma with an extra osseous component. The standard 13G bone biopsy needle is used.
Cisternograms
are used to diagnosis CSF (cerebrospinal fluid) leakage.
A CSF leak can occur after trauma and it is often difficult
to tell exactly where the location of the leakage is.
In order to determine the position of the leak a contrast
material is injected into the subarachnoid space via
a lumbar approach. The patient is then tilted with the
head down and a CT scan is performed to see where the
CSF and the contrast is leaking out. A cisternogram can
also be performed with a nuclear medicine technique.
This is slightly more sensitive but the anatomic resolution
is lower than the CT cisternogram.
Often
the two examinations are combined so that both the CT
and nuclear contrast materials are injected at the same
time. This offers the best anatomic resolution with the
highest sensitivity.
CT
(computed tomography) angiography (CTA) is an examination that
uses x-rays to visualize blood flow in arterial vessels throughout
the body, from arteries serving the brain to those bringing
blood to the lungs, kidneys, and the arms and legs. CT combines
the use of x-rays with computerized analysis of the images.
Beams of x-rays are passed from a rotating device through the
area of interest in the patient's body from several different
angles so as to create cross-sectional images, which then are
assembled by computer into a three-dimensional picture of the
area being studied. Compared to catheter angiography, which
involves injecting contrast material into an artery, CTA is
much less invasive and a more patient-friendly procedure; contrast
material is injected into a vein rather than an artery. This
exam has been used to screen large numbers of individuals for
arterial disease. Most patients have CT angiography without
being admitted to hospital. For
further information see http://www.radiologyinfo.org/content/ct-angiography.htm.
CT
(computed tomography) guided biopsies are done percutaneously
when lesions are not palpable and cannot be done in the clinical
setting. CT guided biopsies offer a noninvasive alternative
to open surgical biopsies.
The
image to the right shows a needle placed inferior to the
foramen ovale. The second case below shows an orbital lesion
that was biopsied with a fine needle technique.
CT
(computed tomography), sometimes called CAT scan, uses special
x-ray equipment to obtain many images from different angles,
and then join them together to show a cross-section of body
tissues and organs. CT scanning provides more detailed information
on head injuries, brain tumors, and other brain diseases than
do regular radiographs (plain films). It also can show bone,
soft tissues, and blood vessels in the same images. CT of the
head and brain is a patient-friendly exam that involves little
radiation exposure.
For further information see http://www.radiologyinfo.org/content/ct_of_the_head.htm
This
is an axial thin section Head CT image that depicts the
brain parenchyma and the fused spaces in the head (ventricular
and subarachnoid space). CT scans are helpful in detecting
abnormalities of the brain.
Face
(Sinus) CT is
typically done to look for fractures or sinus disease.
Neck CT
can
be performed for a multitude of reasons. It can be done to
look for lymph nodes associated with cancer, for traumatic
injuries, and for inflammatory conditions such as an abscess
spreading from the face down towards the neck
Orbit
CT scanning
is performed to evaluate for disease in the orbits such as trauma
or tumors. In this patient there is proptosis on the right side.
Lumbar
Spine CT
Thoracic
Spine CT can
be done for question of other bone conditions evaluated with CT
scans.
This
is a special radiographic test to see if there is blockage
of the tear canals. Radiographic dye is injected into the tear
canal and then radiographic pictures are taken to determine
if the duct is blocked or if there is free flow of tears from
the eye into the nose. It is a simple procedure which causes
no pain and no risk of damage to the eyes or tear ducts. A
few drops of a local anesthetic are instilled into the eye.
A thin probe is placed into the opening of tear duct in the
medial portion of the lower eye lid. A small amount of fluid
is injected through the tear duct and X-ray images are taken.
During injection the fluid may cause some trickling in the
back of the mouth and there may be a bitter taste in the mouth.
The test does not affect eye sight and the patient may drive
immediately after the test is performed.
Dentascan
is a specialized CT scan of the mandible or maxilla often done
before placement of dental implant. Dentascan helps the dental
surgeon to evaluate the dimensions of the jaw bone and assess
the quality of the jaw bone for optimal results of placement
of dental implant. Dentascan
can also be used to study dental pathology when dental x-rays
and panoramic x-rays do not provide the needed information.
Discogram
is a diagnostic test primarily performed to identify the
source of pain. It also gives information about the condition
of the
discs. The patient is initially given intravenous medication
for relaxation and pain, and after local anesthesia a needle
is placed into the suspected disc and a small amount of radiographic
dye is injected. A normal disc will not be painful when a
small amount of dye is injected. However
if the patient's pain is coming from the disc, it is likely that
the contrast injection will cause pain similar to what the patient
normally experiences.
Discography is usually performed
in the lumbar spine but can be done also in the cervical and thoracic
spine.
Cervical
discogram
When the pain is located in the neck and other studies
have not been able to identify the source of the pain cervical
discogram
can sometimes be helpful. Thin needles are place in the disks
and if injection pressure causes significant pain this is
an indication that the pain is originating from the disk
itself. Three or more disks are often injected to make sure
that the painful one is included in the study.
Lumbar discogram
When the pain is thought to be discogenic
and is located in the lumbar spine a discogram of this region
is often helpful to pinpoint
the origin of the pain. Here is a L3/4 through L5/S1 disogram.
The single level discogram illustrates the normal morphology
of the lumbar disk
Functional
MR imaging of the brain is a specialized MR study where the
radio waves in a strong magnetic field are used to measure
the quite and tiny metabolic changes that take place in an
active part of the brain. Physicians know the general area
of the brain where speech, sensation, memory and other functions
occur. However the exact location varies from individual to
individual. Injuries and diseases, such as stroke or brain
tumor, can even cause function to shift to other parts of the
brain. Functional MR imaging cannot only help the radiologist
to look closely at the anatomy of the brain but can help them
to determine precisely which part of the brain is handling
critical functions such as thought, speech, motor activity,
and sensation. This information can be critical when planning
surgery or radiation therapy.
Intraoperative
angiography is done in the operating room during a surgical
procedure of the brain. One common situation is when a brain
aneurysm is clipped. The intraoperative angiogram is done to
make sure that the aneurysm clip is correctly placed. If there
is still a residual aneurysm the clip can be adjusted or another
clip can be placed. In the situation where an adjacent vessel
has been compromised the clip this can also be adjusted.
Magnetic
resonance imaging (MRI) is a method of producing extremely
detailed pictures of body tissues and organs without the need
for x-rays. The electromagnetic energy that is released when
exposing a patient to radio waves in a strong magnetic field
is measured and analyzed by a computer, which forms two- or
three-dimensional images that may be viewed on a TV monitor.
MR angiography (MRA) is an MRI study of the blood vessels.
It utilizes MR technology to detect, diagnose and aid the treatment
of heart disorders, stroke and blood vessel diseases. MRA provides
detailed images of blood vessels without using any contrast
material, although today a special form of contrast usually
is given to make the MR images even clearer. The procedure
is painless, and the magnetic field is not known to cause tissue
damage of any kind.
For further information see http://www.radiologyinfo.org/content/mr-angiography.htm
Head
MR Angiography is
usually done without contrast. The technique is completely
noninvasive and provides a good
visual aid.
Neck
MRA in
this case has been performed with contrast. It covers from
the aortic arch to the Circle of Willis.
MR
diffusion-weighted images (DWI) detect changes in the mobility
of free molecular protons. In all biological systems, the free
diffusion of proton is limited by physical barriers such as
cell membranes or chemical interactions such as bonding to
micromolecules. Comparison of this limited diffusion with the
diffusion characteristics of free water can provide information
on the physical and physiologic conditions of tissue.
MRI
(magnetic resonance imaging) uses radio waves and a strong
magnetic field rather than x-rays to provide remarkably clear
and detailed pictures of internal organs and tissues. This
technique has proved very helpful to radiologists in diagnosing
tumors of the brain as well as disorders of the eyes and the
inner ear. It requires specialized equipment and expertise
and allows evaluation of some body structures that may not
be as visible with other imaging methods.
For further information see http://www.radiologyinfo.org/content/mr_of_the_head.htm
Head
MR
MR Imaging
of the Face and Orbits
is
done for inflammatory neoplastic lesions. Contrast is often given to help improve
the image quality and increase the diagnostic yield.
MR
imaging is occasionally done of the fetus. Usually it is to
look for congenial abnormalities of the brain and often to
clarify something seen on ultrasound. Below are examples of fetal
MR images.
MR imaging complements ultrasound when additional information is needed to make treatment decisions during pregnancy. Up till recently studies were limited by fetal motion but now the scanners are so fast that it is possible to get good images even if the fetus moves. Due to fast imaging techniques now available, images can be obtained in less than 1/2 a second. This means that neither the mother nor the fetus needs to be sedated. MR imaging has proven to be especially beneficial in evaluation of fetal brain abnormalities such as:
MR perfusion
is a specialized MR technique that evaluates the relative
perfusion tissue. Most of the time this is done in association
with contrast enhancement but future techniques are promising
for the possibility of being able to do it without contrast
enhancement. MR perfusion is often done in situations of
tumors of the brain as well as ischemic injuries (stroke).
MR spectroscopy
is a specialized way to analyze the chemical contents of
the brain tissue. It is used to characterize the brain tumors,
infarcts or stroke, metabolic disorders, developmental
disorders
as well as infectious processes. Although MR spectroscopy
is relatively new, it can be very valuable in adding information
to the MR image sequences obtained. For more information see http://www.mritutor.org/mritutor/mrs.htm, http://www.mghneuroradiology.org/NewFiles/mrs.html,
Drug Delivery Patch
If the metallic foil of the patch is in the volume of excitation,
the case should be discussed with the radiologist.
An icepack can be placed directly on the patch since the problem
is heat.
If the patch is removed a specific staff member should be given
responsibility for insuring that it is replaced or repositioned. Accompanying Family/Personnel
Persons who accompany a patient going into the MR scanner should
be screened in the same way as a patient. Fetal MR Contrast Agent
Contrast should be given only when there is overwhelming potential
benefit to the patient and/or fetus outweighing theoretical but
potential real risk of long term exposure to the developing fetus.
MR contrast passes through the placental barrier and enters the
fetal circulation. The MR contrast is filtered in the fetal kidneys
and excreted into the amniotic fluid and may remain in the amniotic
fluid for an indeterminate amount of time until it is reabsorbed
and eliminated. The impact on the fetus from the free gadolinium
ions in the amniotic fluid is unclear. Cardiac Pacemakers and Defibrillators
Pacemakers and defibrillators are contra-indications for routine
MR imaging.
A
myelogram is an x-ray examination of the spinal canal and
its nerves. The purpose of the procedure is to detect whether
there is a compression of the spinal cord or the nerves coming
out of the spinal cord.
In
order to see these nerves an x-ray contrast dye must be injected
into the spinal canal. In
this procedure the skin of the lower back is cleansed and
a local
anesthetic is administered. Then the radiologist or the physicians’ assistant
inserts a needle to inject radiographic contrast and, with
the aid of a TV monitor, x-ray images are obtained that show
the nerve roots. The person performing the study may tilt
the table somewhat to move the contrast along the spinal
canal. You will be instructed which position to assume and
when to avoid breathing while the radiographs are obtained.
Patient
Preparation
The
night before and on the morning of the procedure, the patient
should drink plenty of fluids especially caffeinated products.
The patient may have a light meal up to two hours prior to
the procedure. The patient must arrange to be driven directly
home by another individual after the myelogram. There should
be no eating or drinking for two hours immediately before
the study.
Immediately prior to the myelogram the patient is given oral medication for relaxation and pain control.
Lumbar
CT Myelogram
Lumbar
CT Myelogram - Sagittal view
Lumbar
CT Myelogram - Axial view
Cervical
CT Myelogram
Thoracic
CT Myelogram - Sagittal view
Side
Effects
The
most common side effect is a spinal headache. This is a relatively
uncommon occurrence today with the use of very thin needles.
If it happens it may last from a few hours to several days
and can be treated with over the counter pain medication
in most instances. Less commonly, such headaches are associated
with nausea and vomiting. Persistent nausea and vomiting
may cause dehydration and should be reported promptly to
your primary care physician.
If you develop a severe headache that over the counter medication
does not help or you still have a headache on the second morning following your
myelogram, please call the radiologist at 585-275-2222. Identify yourself as
a post-myelogram patient and ask to be directed to the neuroradiologist on call.
Frequently
asked questions regarding a myelogram
Q.
What is a Myelogram?
A.
A Myelogram is an x-ray study of the spine, that uses dye directly
injected into your spinal canal to show where your spinal cord
or nerves may be damaged by bone or disc in your spine. It is
often used, in addition to an MRI study, to clearly define the
structure of the nerves.
Q.
What must be done before the Myelogram?
A.
The night before and morning of the study,
you must drink plenty of fluids. You may have a light meal
up to
two hours prior to the study, but must not eat or drink for
the two hours just prior to the procedure.You must arrange
for a responsible adult to drive you home and stay with you
the night following the procedure.
You must arrange to bring any prior MRI studies with you for
the procedure.
You cannot return to work after this procedure, and must not
engage in any strenuous
activities for 72 hours.
Q.
Can I take my usual medications before the study?
A.
Yes, with a few exceptions:
COUMADIN/WARFARIN must be stopped at least three days prior
to the study, with permission from the physician who ordered its use. The myelogram
will not be
performed if it is not stopped as directed.
LOVENOX must be stopped 24 hours prior to the procedure. COMPAZINE, and other
PHENOTHIAZINES must be stopped two days prior to the myelogram. Ask your doctor
if you have questions about if any of your medicines must be stopped.
Take all of your other medications as usual, the morning of
the procedure, with a small amount of water. PLEASE take your pain medication
as usual!
Consult your doctor about resuming any medications that had
been stopped for the myelogram.
Q.
What if I have a contrast allergy?
A.
ANY contrast allergy, even if not severe, MUST
be pre-treated with PREDNISONE 50mg tablet at 25 hours, 13 hours,
and one hour prior to the myelogram, and BENADRYL 25-50 mg tablet
2 hours prior to the procedure. The physician ordering the myelogram
will prescribe these for you.
Q.
What are the risks of the procedure?
A.
The most common risk is a headache, which can
be prevented and treated by rest and fluids. It is most likely
to occur during the first 24 hours after, but may occur up to
3 days after the procedure. Other risks are less common, and
will be discussed during the review of your consent form.
Q.
What happens when the test is performed?
A.
You will be on an x-ray table on your stomach
for a study of the lower spine, or on your side for a study of
the upper spine. X-ray guidance will be used to locate the site
to access the spinal canal. Your skin will be numb from a local
anesthetic, a thin needle will be placed to access the spinal
fluid, then the dye will be injected. After this, a series of
x-rays will be taken. This takes about one hour, and completes
the myelogram portion of the procedure. You will then be monitored
by the nursing staff, and will have a CT scan of the spine. You
should expect to be in the hospital for a total of 3-4 hours.
Sacral
biopsies can be performed with CT guidance. In the images below
the lesion was a hemangioma but there was suspicion for a more
aggressive
process.
A
sialogram is performed to diagnose blockage of the salivary
flow due to stones or strictures. This
examination is done by introducing a very thin tube into
the opening of the duct and injecting a small amount of
liquid. This probe procedure is done without any anesthesia
since it is not too painful. It is a simple procedure usually
completed in 30 minutes. Occasionally it can be difficult
to the find the duct opening and in those cases the procedure
with take longer.
The adjacent image is a sialogram of the submandibular
gland that demonstrates stricture of the duct. In
this study, contrast material has been injected into the duct
in the floor of the mouth.
The adjacent image is a sialogram
of the parotid gland with severe inflammatory changes.
This is an 8mm stone removed with a basket under radiologic control.
A
bone biopsy of skull lesions can be done percutaneously
with CT guidance. Such a biopsy might be needed in patients
who have a history of cancer and who develop new lesions
seen on bone scan and/or CT scans. Via a mini incision,
a bone trocar is used to obtain a bone biopsy of the
suspected abnormal skull bone.
A
spinal angiogram is an x-ray study of the blood vessels
supplying the spine. It is usually performed to look
for abnormality of the vessels, so called vascular
malformations. It may also be done to treat a vascular
tumor or a vascular malformation.
A spinal angiogram is done in an angiography suite with an
x-ray machine. You will have to have fasted for 4 to 6 hours before the procedure.
There will be a doctor and nurse and a radiologic technologist in the room. The
groin is anesthetized with local anesthesia and the artery in the groin is punctured
and a long fine catheter is feed up into the artery. The tip of the catheter
is placed in the spinal arteries. Multiple views are needed with multiple injections
of each of the spinal arteries.
Spinal angiograms are often performed to evaluate for arteriovenous
malformations related to the spinal cord. It can be done with MR imaging, but
often conventional angiography is necessary for finer details.
Spinal
angiography is a tedious process because there is
one spinal
artery for each rib and often you cannot tell before
the study which artery is supplying the vascular
malformation. During
the procedure it is important to keep track of which
injection represents which artery since the printed
images look the same and there is no way to count on
the individual images.
In
the images there is a case where we could use MR angiography
to localize which artery was feeding the arteriovenous
malformation, then we would have to do a conventional spinal
digital subtraction angiography.
If
there is a suspicion for tumor or infection of the vertebral
bodies, a biopsy is often needed. This can be done percutaneously
with a needle using x-ray guidance. It is a minimally invasive
procedure that yields diagnostic information in most cases
with little complications.
Using
a special algorithm called maximal intensity projection
we can create a semi-transparent image of the facial structure.
This technique also eliminates practically all artifacts
usually seen in CT scans where the patient has metallic
dental fillings. We often use this technique for evaluation
of facial fractures.
