The flashcards below were created by user
on FreezingBlue Flashcards.
when and how many times should you screen a patient?
- more than once
- the time the appointment is made, when the patient arrives for the appointment, and immediately before entering the MR suite
what are the contraindications for an MRI exam?
- cardiac pacemakers or other electrically, magnetically, or mechanically activated implants
- ferromagnetic aneurysm clips
what are some items that are not contraindicated but are precautions for MRI?
- implanted ferromagnetic materials
- embedded conductive or magnetically active fragments in or near the eye
- magnetic dentures
- fetuses and infants
- decompensated cardiac patients, febrile patients, and patients with an impaired thermoregulation
- permanent eye-liner, facial makeup, or tattoos
when should CPR be started?
on any patient demonstrating cardiac failure
what is a shock?
the result of insufficient blood flow to the tissues and vital organs
what is a quench?
- the abrupt heating and expansion of the cryogen as it changes from the liquid to the gaseous state
- often audible and results in a reduction or complete loss of the magnetic field
- when a quench happens, ventilation pipes are designed to exhaust the helium gas outside of the building
- a problem occurs if some of the helium gas backs up into the MR suite. The gas is colorless, odorless, and tasteless, but does tend to displace the oxygen in the air and therefore presents a risk of suffocation. Any staff or patients should evacuate the area to avoid suffocation and severe frostbite
what is diamagnetic?
materials have a weak, negative susceptibility to magnetic fields. Diamagnetic materials are slightly repelled by a magnetic field and the material does not retain the magnetic properties when the external field is removed
what is paramagnetic?
materials have a small, positive susceptibility to magnetic fields. These materials are slightly attracted by a magnetic field and the material does not retain the magnetic properties when the external field is removed.
what is ferromagnetic?
materials have a large, positive susceptibility to an external magnetic field. They exhibit a strong attraction to magnetic fields and are able to retain their magnetic properties after the external field has been removed
what does contrast do to the T1 and T2 relaxation times of tissues?
- shortens them
- the shorter the T1 relaxation time, the brighter the signal on a T1 weighted image
what is recommended when injecting contrast to pregnant patients?
- express their breasts and not breast feed for 36 to 48 hours after contrast injection
- MR contrast agents are excreted in very low concentrations in human breast milk
what is recommended when injecting contrast to pediatric patients?
- over 2 years is approved
- under 2 is uncertain
what is SAR?
- restriction on how much RF energy is transmitted into the patient's body
- specific absorption rate
- measured in units of watts per kilogram