Pathology
Preparation
mitotic figures
neovascularization
infectiion
inflammation
hemorrhage
nuclei
necrosis
Cerebrovascular
AVM
cavernous angioma
infarct
Congenital
Degenerative
Infection
brain abscess
cysticercosis
Inflammation
Post op
Trauma
Tumor
Preparations
Plain X ray films are images that result when X rays are shown directed through a body onto a sheet of photographic film. Denser tissues absorb more of the x-rays resulting in lighter areas on the film (bone is the densest and appears white). Less dense tissue (such as fat) absorbs less tissue and shows up black on the developed film. Although replaced for evaluation of many nervous system diseases by CT and MRI, skull x-rays are still an important modality.
Dye that absorbs x-rays and that is injected into fluid filled spaces outlines the spaces on x-rays. Following injection of contrast dye into the blood stream through a puncture of the femoral artery blood circulates through the cerebral vasculature which is then imaged on an x-ray image of the head.
Dye that absorbs x-rays and that is injected into fluid filled spaces outlines the spaces on x-rays. Injecting dye into the subarachnoid space (into the thecal sac through a lumbar puncture, into the cervicomedullary subarachnoid space by cisternal puncture) provides an image of the subarachnoid space around the spinal cord, providing an image of this structure and of nerves traveling through it on their way to become peripheral nerves at the neural foramina.
Indications for myelography: MRII is gives excellent images of both the inner and external anatomy of the spinal cord. Myelography is much less useful for imaging of spinal cord tumors. Myelography is still used to image nerve roots although MRI is very good for these as well.
In most cases an MRI is at least as good but usually better than myelography for the evaluation of nerve root pathology. A myelogram may help a neurosurgeon decide if a nerve root that appears to be "pinched" at a neural foramen really is. Some radiologists feel more confident saying that a nerve root is compressed if he or she sees no myelogram dye entering the nerve root sheath.
Today's scans give amazingly precise definition of anatomic and pathologic structures of the brain, skull, and scalp. Although CT does not have the precision of anatomic definition that MRI does, CT is more than adequate to evaluate a number of different lesions -- hematomas, tumors, infections, etc.
Because head CT scans are so ubiquitous in Departments of Emergency Medicine in North America today the standard of care is that any patient suspected of having dangerous intracranial pathology potentially requiring urgent treatment (such as the comatose head trauma patient) should have a CT scan of the head.
CT scans are comparable to MRI in precisely defining the anatomy of bones. For this reason they are frequently ordered in the workup of patients suspected of having traumatic spinal column injuries.
Stains
adio pulses passed through materials placed between powerful magnets cause changes in hydrogen ions that in turn release energy waves detectable by sensors as signals that can be processed and combined by computers to give images of the different tissue densities within an object.
MRI axial cross sectional plane through pons, 4th ventricle, and cerebellum
MR is the best imaging test currently available for evaluating the normal and pathologic anatomy of the central and peripheral nervous system.
MR angiography and functional MR provide information not obtainable using the techniques of standard MR scanning.
Positron emission tomography (PET)
A technique for 2 dimensional imaging that differentiates tissues according to their metabolic activity.
Indications: differentiation radiation necrosis and recurrent tumor.
Radioactive molecules attached to normal biological molecules such as glucose are taken up by cells where they show up on images taken from radioactivity sensors placed in an array generates an image of the organ made up by the tissue that takes up the radioactive molecules.
Findings
mitotic figures
neovascularization
infectiion
inflammation
hemorrhage
nuclei
necrosis