Radiology Flashcards
Densities in the body
By descending order: gas, fat, fluid, bone, metal
How to tell whether a CT or MRI
Look for the bone: CT=cortical bone is white
MRI=cortical bone is DARK
Angiogram= picture of vessels
complication: local hemorrhage emolus allergic death can be used for therappy as well as diagnosis
Contrast agents
Barium for GI tract- swallowed or rectal admin
Water soluble material for tube placement
Intrauterine- hysterosalpingography
Intra-articular-arthography
Intrathecal-myelogram
Intravenous ie for contrast CT MRI
Intra-arterial-angiography
CT Scan
Much better soft tissue resolution than plain films
High radiation dose
Can have severe contrast reactions, including death
Different types of MRI scan
T1 (anatomical): fast to acquire, excellent structural detail (e.g. white and gray matter). T2 (pathological): slower to acquire, therefore usually lower resolution than T1. Excellent for finding lesions.
(Left) Lateral radiograph and (Right) sagittal MRI of the knee. The MRI gives significantly better visualization of the soft tissues than does radiography.(Left)
MRI
Excellent soft-tissue resolution
Not as good as CT for bone
No radiation dose
Noisy, claustrophobic
How to tell whether a CT or MRI
Look for the bone
CT = cortical bone is WHITE
MRI = cortical bone is DARK
Ultrasounds
•Uses high-frequency, sound waves•Principle is that used by bats and in submarines•Pulses of sound pass into the body, are reflected back to the probe and transformed into 2D picture
Ultrasound Terms
•Ultrasound, sonogram, echo• Echogenic, increased echogenicity (hyperechoic), decreased echogenicity (hypoechoic), anechoic• Simple fluid e.g. in a cyst is anechoic (no echoes)• Complex fluid e.g. blood, pus has echoes• Solid tissue has varying degrees of echogenicity• Calcium, bone and air reflect the majority of sound and paper white
Common Ultrasound studies
•OBGYN•Gallbladder – RUQ pain, gallstones etc•Abdominal – pain, mass, fluid•Thyroid – nodules, enlargement•Carotid – TIA, stroke•Guidance for biopsies
Cardiac Ultrasound
•Ultrasound is a safe, accurate method of imaging cardiac anatomy and function
Doppler Ultrasound
•Area of plaque in the carotid bulb producing visible narrowing of the vessel caliber•This would be associated with an increase in velocity of the blood at that site, which can be quantified with ultrasound
Ultrasound
•No ionizing radiation•No known side-effects in levels used•User dependent•Little value in bone and gas containing organs •Very useful for point of care imaging
Metastatic Prostatic Cancer
•A bone scan in a patient with prostate cancer, metastatic to the bones•The white areas in the bones represent areas of increased osteoblastic activity secondary to bone metastases
Common nuclear medicine procedures
- Bone scan* – for metastatic disease
- Cardiac scan* – myocardial function
- HIDA scan* – for gallbladder function
- Thyroid scan* – thyroid nodules, treatment with radioactive iodine
Nuclear Medicine
Uses ionizing radiation
Poor spatial resolution
Can show function as well as anatomy
PET/CT very important in oncology
Plain fims
5 different densities: oGasoFatoFluidoBoneoMetal- increasing order
You need two or more images
Soft tissue differentiation is not good
Radiographic Imaging
•Radiographic imaging is a 2-Dimensional representation of 3-Dimensional structures•You need at least two images at 90-degrees to each other
