Imaging of circulatory disturbances Flashcards
Types of anatomical vascular imaging? (5)
Plain films - simple x-ray contrast angiography ultrasound CT MRI
Types of functional vascular imaging? (3)
Radionuclide Imaging
MRI functional imaging
Ultrasound
problems with vascular imaging?
Soft tissue contrast - contrast between different soft tissues can only be enhanced by the injection of contrast media
Functional significance of lesions (ie how does it affect bodily function)
Is treatment effective
Structures in order of density in radiographic imaging? (most dense to least dense)
Metal Bone Muscle Fat Air
What does radiographic contrast allow you to discriminate between?
different vascular structures between their densities
which important structures can’t be seen very well?
Blood vessels
Lumen of hollow viscera
What are the ideal properties of a man-made contrast agent in radiology?
Inert
Unequal distribution in and out of selected body compartments –so you can tell where the vessel starts and stops
Painless
Easy to use
cheap
Iodinated Contrast
Differential X Ray attenuation Inert Stable in selected body compartments Painless Easy to use Cheap
Problems with Iodinated Contrast (6)
Major Reactions (allergic) Renal Dysfunction – molecules are quite large Disturbance of Thyroid Metabolism Disturbance of Clotting Seizures Pulmonary oedema
Parenteral Iodinated Contrast ie IV, IM, SC - common effects (6)
Metallic Taste Feeling of warmth Arterial injections Micturition - urination Discomfort Rarely nausea
Metformin and complications with iodinated contrast
used to treat type 2 diabetes
serious reaction as your kidneys may not be able to properly remove metformin from your blood.
If a patient has had a previous contrast reaction then what is the next reaction like?
more severe
asthma/atopy and iodinated contrast
asthma - more likely to develop bronchospasm
define atopy
genetic tendency to develop allergic diseases such as allergic rhinitis, asthma and atopic dermatitis eczema
What is a catheter angiography
Vessel punctured and catheterised
Sterile procedure
Contrast injected using pump injector
Rapid series of images acquired - arteries, veins, and the heart chambers
what is digital subtraction imaging?
take initial image and then take another and then take one away from the other – only shows vessels
e.g angiography
Uncontrolled arterial injury
blood spills out into tissues - non-contained
Types of interventional Radiology (6)
Minimal invasive treatment of lots of things
Angiography / Angioplasty
Embolisation
Catheter thrombolysis
Drainage of abscesses
Nephrostomy
Vertebroplasty
when to use angioplasty?
Short stenoses or occlusions
Sessile / concentric plaques
Iliac > sfa > popliteal > crural - bigger the vessel the better the result. More proximal the problem, the more likely you are to get a solution
A balloon to stretch open a narrowed or blocked artery. Most modern angioplasty procedures also involve inserting a short wire-mesh tube, called a stent, into the artery during the procedure.
Carbon dioxide as a contrast agent
CO2 is quite safe - it gets absorbed really quickly by vessels
Useful in patients with poor renal function or sensitivity to iodinated contrast agents
What is a negative contrast agent
gases of low density (air, oxygen, carbon dioxide) which appear radiolucent.
Problems with Angioplasty
Occlusion
Dissection – tear in lining – get second channel of blood flow
Embolisation
Rupture
Infection
pros/cons of ultrasound of vascular disturbances
No radiation dose
Quick, portable
non invasive
resolution vs penetration
may be more physiological
operator dependant
variable imaging quality
true or false:- ultrasound can show direction of blood flow
true
what is lung scintigraphy?
lung scan
image using gamma camera
patient has to breath in an aerosol that will localise in the alveoli - tracer
V/Q lung scan, is a type of medical imaging using scintigraphy and medical isotopes - examines airflow (ventilation) and blood flow (perfusion) in the lungs.
mainly used to exclude pulmonary embolism (PE)
applications of radionuclide imaging (3)
Perfusion of transplant kidneys
Blood loss into gastrointestinal tract
Cerebrovascular perfusion - dementia
CT angiogram
Gives information about other structures Sensitive IV injection only Radiation Dose High Contrast Dose Expensive
MR angiography pros and cons
Sensitive
Specific
No radiation
No nephrotoxic contrast
Very expensive
Needs state of the art machinery
High contrast cost
out of CTA and MRA which is better for females of child baring age
MRA - prevent exposure to radiation
consent and radiology
newly qualified doctors should not routinely obtain consent from patients
the doctor performing the interventional procedure should be the one to obtain consent from the patient
only when a newly qualified doctor has detailed knowledge from active involvement and experience in interventional studies should they gain informed consent from patients
reaction that contrast media may induce can range from…
mild rash to severe, acute anaphylaxis
gold standard imaging option for DVT
contrast venography
However, this procedure is invasive, not always technically possible, and it carries a small risk of an allergic reaction or venous thrombosis.
what imaging is appropriate for abdominal pain due to suspected abdominal aortic aneurysm leak
CT
