15- Vascular CT, MRI and ultrasound diagnostic methods. Vascular malformations.

what are the imaging diagnostic used

• Dopped US- first imaging used

• CT or MR angiography- diagnosis + planning interventions

describe doppler US

• uses sound waves to produce images of blood moving through circulatory system

• shows- direction, speed of blood flow

what is the mechanism of doppler US

• RBC will backscatter US beam to transducer

• frequency is higher when target moves towards transducer

what are the doppler types

• Colour

  • assess flow velocity + visualise with colour

• pulsed wave

  • short US that after delay records refracted and changed US

• continuous wave

  • constant US beam, measures flow velocity but not depth

what is CT angiography

• CT used to visualise vessels using contrast agent that is injected into blood vessels → see blockages, aneurysms, dissections, stenosis

• fast, non invasive, cheap, can characterise plaques

what are the types + uses of CTA

• Aortic CT angiography:

  • acute aortic syndrome, aortic injury, thrombosis

• Carotid CT angiography:

  • acute stroke, carotid stenosis, surgical planning

• Lower limb CT angiography:

  • claudication, critical lower limb ischemia, acute embolism, surgery/interventional treatment planning

• Pulmonary CT angiography:

  • symptoms of acute PE, pulmonary HT

what are MRI

• MRI used to image blood vessels without using ionising radiation

what is the mechanism of MRI

• imagines with injecting contrast dye

• normal tissue is enhanced together with scars

• ischemic tissue is not

• check heart viability exams

• accurate haemodynamic parameters

what are the indications of MRI

• evaluation of V function- gold standard

• assessment of ischemia, myocardial viability, CM

• evaluation of congenital heart disease, valvular heart disease

what are the contraindications of MRI

• pacemaker/ ICD

• mechanical valve

• metallic foreign bodies

• hearing aids

• insulin pumps

what are vascular malformations

• abnormalities in vessels- abnormal growth and development

• usually present at birth

  • might only be evident later in life

• can develop in any part of body

• can be present as soft tissue mass, pain, swelling, skin discolouration

what are the types of vascular malformations

• arteriovenous malformation

• venous malformations

• cavernous malformations

• lymphatic malformation

describe arteriovenous malformations

• abnormal connection between arteries and vein

  • bypassing capillary system → appears as a tangle of vessels

• arteries pump blood directly into veins

describe cavernous malformations

• tightly packed capillaries in brain have long “caverns”
• blood moves slowly through caverns

describe lymphatic malformations

• dilated lymphatic channels forming fluid containing cysts tend to develop in soft tissues of the face, neck, axillary regions

what are the symptoms of vascular malformations

• depends on malformation
• can affect skin →
  • raised red/ blue/ brown birthmark → swell, bleed, pain
• cerebral AVM
  • headache, seizures, paralysis, intracranial haemorrhage
• pulmonary AVM
  • dyspnea, reduced gas exchange
• fast flow AVM
  • blood moves fast from arteries to veins
  • fast flow in large AVMs can cause heart to work harder → incrase risk of HF

how do you diagnose vascular malformations

• US → enlarged arteries and dilated veins, high flow
• MRI + CT → large arteries, draining veins, rapid AV shunt

how do you treat vascular malformations

• minimise symptoms + reduce potential complications
• most are treated by closing off or surgically remove affected vessels
  • sclerotherapy, catheter embolisation, laser, radiation

what is the difference between VM and haemangiomas

• haemangioma
  • benign vascular tumour, clump of vessels under the skin, rapidly growing in infants
  • rarely causes problems, goes away without treatment
• VM
  • present at birth, slow growing
  • usually needs treatmen