Magnetic Resonance Imaging MRI

MRI Becoming the imaging method of choice in small animal medicine Superior, high-contrast anatomically detailed images of soft tissue Non-invasive Multiple image planes

MRI Radiography and CT use x-rays MRI uses electromagnetic signal emitted from protons in different tissues

How does it work? Complex Manipulates the energy state of protons Powerful magnet

How does it work? Radiofrequency pulse applied Allowed to return to original state

How does it work? Relaxation Receiver coil detects signal Occurs at different rates in different tissues Leads to the release of energy Signal Receiver coil detects signal Computer displays signal data as image Shade of grey assigned based on difference Contrast media Further differentiate tissues

Contrast Media Gadolinium Areas that retain agent appear lighter on final image

MRI Advantages Primarily a diagnostic tool Can help locate neoplasm for excision or irradiation Used when traditional diagnostic imaging cannot work – as in CNS Comparable to CT in results obtained

MRI Disadvantages Cost Sedation/General anesthesia use Transport of patient Lack of facilities Becoming more prevalent

MRI Disadvantages Safety Microchips Pacemakers Magnetic metals –bbs, bullets, metal shaving (eye) Nothing in room that is metal Equipment certified MRI safe

MRI Indications for use CNS disorders Seizures, ataxia, cranial nerve abnormalities, paresis, paralysis

MRI Indications for use Neoplasms Inflammatory Conditions Hemorrhage and Infarction Seizures Spinal Cord and Vertebral Column Disorders Nasal Tumors Eye and orbital disease Musculoskelatal Conditions Vascular abnormalities Bulla disorders