Magnetic Resonance Imaging MRI MRI Becoming the imaging

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 – 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