4. DSA - principles, indications, contraindications

DES =

= drug-eluting stent - stent is placed into a narrowed vessel and slowly releases a rug to block cell proliferation (prevent fibrosis -> restenosis)

Contraindications:

Allergy to contrast medium Renal dysfunction Deranged coagulogram.

Principles:

Based on the principle of fluoroscopy • Real-time subtraction of pre- and post- contrast injection images o Water-soluble iodine-containing contrast medium (CO2) o Blood vessels are not normally seen in an x-ray image due to low contrast. o Iodine absorbs photons more than blood and tissue. • Improves the perception of vessels with removal of background anatomy (bones)

(DSA) Digital subtraction angiography

Classical invasive method to clearly visualize blood vessels in a bony or dense ST environment. • It is the basis of all interventional procedures o Therapeutic = diseases/conditions are treated through endovascular acesss. o Diagnostic investigations are being replaced by sectional imaging .e.g CT or MRI angiography.

Complications

Complications: rare Hematoma (subcutaneous) Retroperitoneal hemorrhage Thromboembolism, dissection of vessel wall, infection

Types of substractions

Mask mode substraction Time-interval difference subtraction Dual energy subtraction Hybrid substraction K-edge substraction

Procedure:

Seldinger technique Local anesthesia • Puncture of common femoral artery (ipsilatera, contralateral), just below the inguinal ligament with sharp hollow needle o Alternatives: axillary, brachial, radial, popliteal a. o Transradial: more used by cardiologists - less risk of bleeding, but higher risk of occlusion. o Venous system: femoral or popliteal veins o Transfermoal: best approach - the diameter of the puncture site is quite big (7mm), it is closed to the head of femur (after procedure we can compress the puncture site to stop the bleeding). o Currently we have different devices to occlude puncture site after procedure, so risk of bleeding is now very low. • Guidewire is advanced through the lumen of the needle and the needle is withdrawn. • Sheath is passed over the guidewire into the vessel and the guidewire is removed. • Sheath can be used to introduce catheter or other devices to perform endoluminal procedures. o Pigtail catheter: typically used for an overview angiography. o Sidewinder: selective or super-selective depiction of vessel. • Add iodine contrast

Indications:

Therapeutic: embolization, coiling, stenting, thrombolysis, thrombectomy • Usually combined with endovascular treatment: Diagnostic: thrombosis, aneurysm, arterial dissection, non-traumatic SAH, AVM, AVF, tumour vascularity • Rarely for diagnostic purpose anymore, CTA and MRA are preffered.

Hybrid substraction:

combination of temporal subtraction + dual energy

DEB

drug-eluting balloons - angioplasty balloon covered with an anti-proliferative drug which is released into the vessel during inflation of the balloon.

SyngoiFlow:

new digital DSA software - Help with visualization and improve diagnosis. - Automates the process to produce a color image highlighting the pat of the contrast medium.

PTA-POBA

percutaneous transluminal angioplasty - plain old balloon angioplasty

Sidewinder

selective or super-selective depiction of vessel.

K-edge substraction:

substraction: removal of all x-rays from the beam except those that lie below the k-shell

Dual energy subtraction:

subtraction: elimination of motion artifacts • Higher kV image is subtracted from lower kV image

Time-interval difference subtraction:

temporal subtraction - cardiac imaging (rapid motion) • Consecutive previous frame is subtracted from current frame

Mask-mode substraction

temporal subtraction - most widely used • First image: stabilize the exposure factors • Second image: stored as mask image • Mask image is subtracted from subsequently acquired images (1-6 images per sec)

Diagnostic:

thrombosis, aneurysm, arterial dissection, non-traumatic SAH, AVM, AVF, tumour vascularity • Rarely for diagnostic purpose anymore, CTA and MRA are preffered.

o Pigtail catheter:

typically used for an overview angiography.