MRI Advanced Test.

MRI is a modality that uses - correct answer Strong magnetic fields and radio waves to generate very detailed images of the body without the use of radiation Mri is superior to ct in imaging the - correct answer Central nervous system, ie. The evaluation of of acute stroke and metastatic disease Mri is primarily based on the - correct answer Hydrogen atom Why is mri based primarily on hydrogen atom - correct answer Water is about two thirds of the body weight and therefore there is an abundance of hydrogen for imaging, and due to one electron spinning around one photon, hydrogen molecules are by design magnets and are easily influenced by strong magnetic fields Electromagnetism is created by - correct answer Passing an electrical current through a wire that is wrapped around an iron core Three types of magnets - correct answer Permanent, resistive, superconducting Permanent magnets - correct answer Require no external power supply and are low in capital and operating costs, operate at low magnetic field strengths, are extremely heavy and can restrict where the magnet can be placed within a building Resistive magnets - correct answer Are electromagnets, but they are not cooled to superconductivity, therefore they are somewhat limited to lower magnetic field strengths, are expensive to operate because they need a constant supply of electricity to maintain the magnetic field Superconducting magnets - correct answer Designed with virtually no electrical resistance because it is supercooled, the cooling is accomplished by insulating the magnet with liquid helium, are more expensive, but generate very high field strengths for faster and more diverse imaging techniques, these are most common Magnetic field strength is measured in units called - correct answer Gauss, and tesla (1 tesla = 10,000 gauss) Most superconducting magnets operate at - correct answer 1-3 tesla, with research magnets operating at 4 tesla and above Magnetic resonance angiography and venography are imagine of the - correct answer Arterial and venous structures without and with the use of contrast materials A non invasive alternative to ERCP - correct answer Magnetic resonance cholangiopancreatography Analyzes tissue for specific chemicals to qualify MR image findings, can be performed in the brain, breast, prostate, liver - correct answer Magnetic resonance spectroscopy This can be used to evaluate cardiac morphology, ventricular wall motion, valve function, congenital defects and to assess for tissue viability and damage post MI - correct answer Cardiac MR Non invasive mapping of brain functions in preoperative patients or in research settings. Allows doctors to view locations of critical brain functions prior to biopsy or removal of tumor/vascular malformations - correct answer Functional MRI Real time imaging during surgical procedures, require mr compatible monitoring equipment as well as surgical instruments - correct answer Intraopertive MRI Imagine is done with IV and oral contrast to evaluate for GI abnormalities in patient with Chrohn's disease and those with colitis - correct answer MR enterography Advantages of MRI - correct answer No ionizing radiation, no known harmful effects, non invasive, direct multiplanar imaging,detection of soft tissue and bony abnormalities, in utero imaging of fetus Disadvantages of MRI - correct answer Inability of patient to be motionless or to follow directions, tattoos and piercings, intracranial aneurysm clips must be documented to be safe at the magnetic field, claustrophobia This is an injected paramagnetic contrast material that shortens T1 relaxation times and has a similar diagnostic value to iodinated contrast in xray imaging - correct answer Gadolinium Risk factors looked at prior to receiving contrast - correct answer Diabetes, hypertension, being over 60, history of renal or liver transplants Bigger and shorter magnet bores on high field MR systems offer reduced - correct answer Claustrophobia and are able to accept larger patients