4) DSA - principles, indications, contraindications.

Types of subtractions

1) Mask-mode subtraction: It most widely used a) First image is stabilize the exposure factors b) Second image is stored as mask image c) mask image is subtracted from subsequently acquired images 2) Time-interval difference subtraction = Temporal subtraction: cardiac imaging (rapid motion) a) Previous image is subtracted from current frame. 3) Dual energy subtraction: Higher kV image is subtracted from lower kV image. Það eru fleiri til en þetta er svona helsta. Ef ég treysti mér í að muna meira farðu i compendium.

What are contraindications

Allergy to contrast medium Renal dysfunction = use then CO2 Deranged coagulogram CO2 = has risk of cardiotoxicity and neurotoxicity COPD patients patients on nitrous oxide anesthesia: may increase the volume of the CO2 bubbles leading to pulmonary artery vapor lock which may be fatal

Auka

Hann vildi vita hvar maður sprautar CO2 contrast og það er infradiaphramic eða fyrir neðan diaphram. CO2 er negative contrast medium.

What is the principle

It is based on the principle of fluoroscopy - real time subtraction of pre and post contrast injection images. - Water soluble iodine containing contrast medium - CO2 is used in patients with renal insufficiency or iodine hypersensitivity. - Iodine absorbs photons more than blood and tissue. - blood vessels are not normally seen in an x-ray image due to low contrast. - Improves the perception of vessels with removal of background anatomy.

new type of DSA

Syngo iflow 1) Help with visualization and improve diagnosis 2) Automates the process to produce a color image highlighting the part of the contrast medium. Very good for treating intracranial ateriovenous malformation.

Indication?

Therapeutic: embolization, coiling, stenting, thrombolysis, thrombectomy. - It is usually combined with endovascular treatment a) PTA = Percutaneous transluminal angioplasty b) DEB = Drug- eluting balloons c) DES = Drug- eluting stent - placed into narrow vessels that are coated with antiproliferative substances (immunosuppressant drugs, cytostatic drugs) that prevent excessive intimal hyperplasia DIAGNOSTICS: Thrombosis, Aneurysm, arterial dissection, non-traumatic subarachnoid hemorrhage, Arteriovenous malformation, tumour vascularity, arteriovenous fistula, Also have a high diagnostic rate of peripheral vascular diseases. - It is rarely used today for diagnostics purpous.

DSA?

digital subtraction angiography - classical invasive method to clearly visualize blood vessels in a bony or dense subcutaneous tissue environment. - It is the basis of all interventional procedures. a) therapeutic = treated through endovascular access b) Diagnostic investigation of blood vessels.

Procedure

https://youtu.be/BtxLQvGkSkM It is called Seldinger technique 1) Local anesthesia 2) Puncture of common femoral artery (ipsilateral, contralateral), just below the inguinal ligament with sharp hollow needle. - alternatives: axillary, brachial, radial, popliteal - Transfemoral is the best approach. 3) Guidewire is advanced through the lumen of the needle and the needle is withdrawn. 4) Dilation of the tract 5) Sheath is passed over the guidewire into the vessel and the guidewire is removed. 6) Sheath can be used to introduce catheter or other devices to perform endoluminal procedures - pigtail catheter: typically used for an overview angiopraghy - Sidewinder: Selective or super-selective depiction of vessel. 7) Add iodine contrast.