Diagnostic tests

DIAGNOSTIC/ELECTRODIAGNOSTIC
TESTING

COMPUTED TOMOGRAPHY (CT)


Imaging procedure where detailed information is obtained from thin section in collimated X-rays.

Indications
• Evaluation of bony structure, especially cortical bone.
• Useful for diagnosis in compound fracture, dislocations, stress fracture and spinal pathologies.
• Structural evaluation of lung, mediastinal pathologies.
• Structural analysis of intracranial lesions.
• Evaluation and comparison of the normal organ and abdominal tissues.

Contraindications
• Restless patient
• Pregnancy.

MAGNETIC RESONANCE IMAGING (MRI)


Cross sectional image is formed by certain atomic nuclei, which possess unpaired protons or
neutrons, possess an inherent spin. Positive charged nucleus generates a small magnetic field around itself, when it spins. Those signals emitted by the nuclei are measured and reconstructed by computer to create an image of soft tissue and bone.

Advantages
• Noninvasive.
• Give high intrinsic contrast.
• No bony or air defect.
• No known biological hazards.
• Sagittal, transverse imaging are possible.
• It does not involve the use of ionizing
radiation.


Disadvantages
• Patients may produce artifacts, because imaging time is long.
• Expansive.
• Require trained technical staff.
• Patient with a cardiac pacemaker, brain aneurysm clip or other metallic implants with the exception of those attached to the bone, i.e. prosthetic joints cannot be scanned.

ULTRASOUND


Based on piezo-electric effect which is the property of certain substances to convert electrical
energy to sound energy. These are the active portions of the ultrasonic transducers. Can be
used to examine a broad range of soft tissue structures.

Advantages
• Noninvasive.
• Cost-effective.
• Widely available.
• Also used in wards.
• Does not involve the use of ionizing radiation and can therefore be safely used in a pregnant women.


Disadvantages
• Limited in thorax.
• Cannot image the bone.
• Limited use in the abdomen when there is gaseous distension.

RADIOGRAPHY


Oldest imaging technique, formed by exposure to short wavelengths of X-rays that pass through the body and hit a photographic receptor placed behind the patient body.

• In dentistry
• Mammography
• Chest examinations
• Diagnosis of fractures.
Hollow organ can be visualized by filling them with a radiopaque substances. These block the X-rays and visualize the structures.


Angiography: Visualization of the blood vessels.
Arthrography: Visualize the degenerations of the joints.
Discography: Visualize the disc pathology.
Myelography: Visualize the compressive lesions of the spinal cord and cauda equine.
Tenography: Visualize the tendon pathology and ligaments ruptures.

ELECTROENCEPHALOGRAPHY (EEG)


Electroencephalography examines by means of scalp electrode the spontaneous electrical activity
of the brain. Tiny electrical potentials, which recorded, amplified and displayed on either 8 or
16 channels of a pen recorder. Mainly used in diagnosis of coma, epilepsy and certain forms of
encephalitis.

ELECTROMYOGRAPHY (EMG)


Electromyography is a technique used in studying the electrical activity of the muscles for the diagnosis of neuromuscular disease. Used in the diagnosis of a broad range of myopathies and neuropathies.

NERVE CONDUCTION STUDIES (NCV)


Recording technique of a peripheral nerve impulses at same location, which may distant from the site from where the propagating action potential is induced in that peripheral nerves. Mainly used in the diagnosis of nerve entrapments, peripheral neuropathies, motor and sensory nerve damage and multifocal motor neuropathies.


EVOKED POTENTIALS (EP)


An electrical response recorded from the brain, the spinal cord or the peripheral nerve that is evoked by various external stimuli such as visual (e.g. flashing the light), auditory (click sound),
somatosensory (electrical stimulation), etc. The recording electrodes are placed over the scalp,
neck or spine surface, which vary depending on the type of stimulus modality to be tested. Mainly used for detecting multiple sclerosis, brainstem and cerebellopontine angle lesions, various cerebral metabolic disorders in infants and children

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