Diagnostic Imaging Flashcards
What diagnostic imaging uses ionising radiation?
X-ray, CT and nuclear medicine
What diagnostic imaging doesn’t use ionising radiation?
MRI, ultrasound
In X-rays: What body tissues are black, grey and white?
Black: Air/fat Grey: Soft tissue White: Bone, calcium, metal, contrast agents
How is tissue contrast improved?
Contrast agents: Barium, Iodine -> introduced by swallowing, via rectum, artery, vein
What are CT scans?
Computed tomography: X-rays spin around patient and detector feeds info to computer, which form the cross-sectional map of tissue
How do the different tissues appear on the CT?
Same as X-rays but can differentiate soft tissue and water: water - dark grey
What is special about CTs?
Can form windows - focusing on each tissue in the body Can take images from different planes: sagittal, axial, coronal -> so can form 3D images
What contrast agents are used in CTs?
Iodine injected into arm vein during scan - makes blood vessels easier to see and differentiates pathological from normal tissue
What is ultrasound?
High frequency sound to make images - completely safe
How has US advanced?
Images used to be difficult to interpret but now there are 3D versions, and have become pocket US machines
What is MRI?
Strong magnet, supercooled with liquid He or N2 Transmits radio waves, and sound returns to form image
How does MRI T1 and 2 differentiate?
Cortical bone - Black Bone marrow - White Soft tissue - Grey Fluid - T1(Black) T2(White) Fat - White Air - Black
What is nuclear medicine?
Radioactive tracers that emit radiation with images firmed by detecting radiation coming out of the patient
What is Positron Emission Tomography?
Detects metabolic or function changes, effective in identifying cancer - if present, spreading or responding to treatment
What combination of diagnostic imaging is good for localisation of cancers?
PET, CT, MRI - more specific than PET alone
