Introduction to Radiology What you need to know about imaging to get through the next four years Mark Chambers D.V.M., Ph.D., M.D.

Topics of Discussion How to approach reading any image What are the different imaging modalities What imaging modality is this Tips and tricks for image interpretation Practice! Practice! Practice!

How to Approach Reading any Image Identify the patient When was the image taken Are these the proper images The five densities Are the images technically adequate

Identify the Patient Always look for the patient name and/or number Even if the film came out of the “right” folder If something seems “wrong”, double check

When was the Image Taken Observe dates and times closely, especially with serial images Date “stickers” (color keyed)

Are these the Proper Images Correct type of study Correct / complete views Correct limb Contrast

The Five Densities Metal Bone Soft tissue (water) Fat Gas

Are the Images Technically Adequate Exposure Development / display Positioning Proper contrast Artifacts Movement Interference

What are the Different Imaging Modalities Radiography “plain films” Computed axial tomography “CT” Magnetic resonance imaging “MRI” Ultrasound “US” Interventional radiology “angio”

Radiography Also called “plain films” or “standard films” Image formed using broad beam ionizing radiation The image formed is related to the subjects density May involve the use of contrast agents Iodinated Barium Air

Computed Axial Tomography Also called CAT scanning or “CT” Image formed using a rotating thin beam(s) of ionizing radiation Image “slices” reconstructed by computation The image formed is related to the subjects density Image display on computer or multiple films New technology is multislice helical scanner

Magnetic Resonance Imaging Also called “MRI” (used to be NMRI) Image formed by transmitting and receiving radio waves inside a high magnetic field Image “slices” reconstructed by computation The image formed is related to: Scanner settings Patient hydrogen density Patient hydrogen chemical/physical environment Image display on computer or multiple films

Ultrasound Also called “sono” or “echo” or “US” Image formed by transmitting and receiving high frequency sound waves Image “slices” reconstructed by computation The image formed is related to interfaces between tissue areas of differing sound transmission characteristics Image display on computer or multiple films

Interventional Radiology Also called angiography or “angio” or “IR” Image formed using broad beam ionizing radiation (fluoroscopy) Images acquired using digital detector and processed by computer The image formed is related to the subjects density Usually involves the use of iodinated contrast agents and long catheters Many varied techniques including the use of CT or MRI Image display on computer or multiple films

What Imaging Modality is this Is it plain film or interventional Is it CT or MRI

Plain Film or Interventional May look very similar Angio studies usually printed on large sheet film like CT or MRI Will usually see catheter or needle, often with contrast in IR studies

CT or MRI CT images are tissue density related Brightness and contrast may vary Bone is brighter than fat MRI is not density related Bone is darker than other tissues

Tips and Tricks for Image Interpretation The “quick read” technique Scrolling through axial images

The “quick read” Technique Why did you order the image What did you expect to see Do you see it Now start over fresh

Scrolling Through Axial Images Rapid paging through sequential images On computer display of CT and MRI images Allows you to follow long/large structures Helps rapidly identify small higher contrast areas

Practice! Practice! Practice! Radiology, News, Education, Service Teenage male with severe left arm pain after hit while playing football. Man with leg swelling and mass in popliteal fossa. History of trauma 8 months ago. Fifty-year-old woman originally presenting with headaches and claudication.