CT - Computed Tomography
MRI - magnetic resonance imaging
The selection of imaging modality depends on the ease of identification of the target lesion and surrounding structures
Pt cooperation and stillness are crucial to obtaining the best image resolution
Most procedures can be done with conscious sedation, but some may need GA
CT and MRI use an automated table to transfer pt into the imaging device
All equipment must be non-ferromagnetic
No metals on pt or staff
ECG - use MRI-compatible electrodes and place leads to avoid creating loops
V5 and V6 are least likely to develop artifacts
Pulse Ox - place it outside the MRI, possibly using the toe
NIBP - replace ferrous connections on the cuff and tubing with nylon connectors
A-line - use MRI-compatible tubing
Stethoscope - MRI-compatible, infrared, wireless stethoscope is available
Temperature - MRI compatible available if needed
Capnography - MRI compatible is available, but not accurate due to the long pathway. Suitable for trend and RR
Foley – if it has a temperature probe, it must be disconnected and placed straight on the MRI table to avoid any skin contact and risk of burn
Verbal/visual vigilance
Pad well to prevent any nerve damage
Check eyes
Positioning can be challenging - supine, prone, or lateral
Propofol infusion 25-200 mcg/kg/min
Use micro drip infusion set
Midazolam 0.025-0.1 mg/kg titrated to effect
Children, mentally retarded, claustrophobic, uncooperative, or critically ill patients require general anesthesia
Induction outside MRI in the anteroom
Propofol infusion with micro drip chamber
Extubation in the anteroom
To PACU for recovery with monitors/O2
Gadolinium - local and systemic reaction
N/V, itching, urticaria, sensation of warmth, pain, anxiety, rash
Hemiplegia, blindness, aphasia, and decreased consciousness - may be related to the hyperosmolarity of the agent.
Bronchospasm, low BP, cardiac arrest, pulmonary edema, laryngeal edema, dysrhythmias
Tx with epinephrine, 0.25-0.5 mg IV
Tx anaphylaxis with securing airway, 100% O2, IV fluids, epinephrine, diphenhydramine, ranitidine, steroids
Panic attacks and claustrophobia seen in 5-10% of pts
Temporary hearing loss and tinnitus may be expected in 40% of pts. Use earplugs. GA increased the risk of hearing damage secondary to stapedius muscle relaxation. The stapedius is the tiniest skeletal muscle in the human body. At just over one millimeter in length, its purpose is to stabilize the smallest bone in the body, the stapes. It reflexively dampens the vibrations of the stapes by pulling on the neck of that bone. It prevents excess movement by the stapes, helping to control the amplitude of sound waves from the general external environment to the inner ear.
From induced current, heating of the oximeter probe, and unintentional looping of the cables