introduction to interventional radiology

Introduction to

Interventional

Radiology

Dr. Ahmed Alsharef FarahDr. Ahmed Alsharef Farah 1

• Interventional radiology (IR) is a specialtythat uses image guidance to assist in theperformance of minimally invasive procedures.

Dr. Ahmed Alsharef Farah 2

• The diagnostic and therapeutic proceduresoffered by interventional radiologist cover awide variety of organ systems requiringknowledge and interaction with many differentsubspecialties.


• Interventional radiology has a therapeuticrather than diagnostic purpose in that itintervenes in, or interferes with, the course of adisease process or other medical condition.

• Every interventional radiologic proceduremust include two integral processes.


• The first is the interventional or medical sideof the procedure, in which the highly skilledradiologist uses needles, catheters, and specialmedical devices (e.g., occluding coils, guidewires) to produce an improvement in thepatient's status or condition.


• The second process involves the use offluoroscopy and radiography to guide anddocument the progress of the steps taken duringthe first process.


• The CIT must receive special education in theangiographic and interventional suite.

• This skilled CIT has a very important role inassisting the angiographer in the interventionalprocedures.


• The first angiogram was performed onlymonths after Roentgen's discovery of x-rays.

• Two physicians injected mercury salts into anamputated hand and created an image of thearteries.

History


Post mortem injection of mercury salts in Jan,1896.Dr. Ahmed Alsharef Farah 9

• Interventional radiologic procedures began in1930s with angiography.

• In early 1960s Mason Jones pioneeredtransbrachial selective coronary angiography.

• Later in 1960s transfemoral angiography wasdeveloped.


• Arterial access.• In 1953 Seldinger described a method for

catheterization of vessels.• A Percutaneous technique for arterial and

venous access.• Femoral artery is most commonly used.

Basic principles:


Interventional

Radiology Procedures


• Diagnosis & presence of ischemic heart disease.• After revascularization procedures.• Congenital heart lesions & anomalies of great

vessels.• Valve disease, myocardial disease & ventricular

function.

Indications:


• Atheroma.• Aneurysms.• Arteriovenous malformations.• Arterial ischemia.• Trauma.


1. Vascular.2. Non-Vascular.

Interventional Radiology Procedures:


1. Vascular:

• Angiography.• Stenting.• Embolization.• Chemotherapy infusion.• Thrombolysis.• Transjugular intrahepatic portosystemic shunts.• Venous access.• Vena cava filter placement.


2. Nonvascular:

• Biopsy.• Abscess drainage.• Biliary drainage.• Gastrostomy tube placement.• Nephrostomy.• Stone extraction.• Foreign body retrieval.• Screw placement.


• Explain procedure & risk to the patient.• History & physical examination.• Lab tests.• Consent.• Pre procedure I/V fluids.• Medication to relieve anxiety.

Patient preparation:


• ECG, Automatic BP measurement & pulse oximetry.

• Life saving drugs and equipments.• Immobile for minimum 4hrs after.• Vital signs monitored.• Puncture site inspected.

Monitoring during and after procedure:


• Contrast allergy.• Impaired renal function.• Blood- clotting disorders.• Anti coagulant medication.• Unstable cardio pulmonary/ neurological status.

Contra-indications:


• Bleeding at puncture site.• Thrombus formation.• Embolus formation – Plaque dislodged from

vessel wall by catheter.• Dissection of vessel.• Puncture site infection.• Contrast reaction.

Risks:


• Specifically designed to accommodate thequantity of equipment needed & the largenumber of people involved in the procedure.

Interventional radiology suite:


• Procedure Room:

Room size: 400 - 600 square feet.Easily cleaned (Floors, Wall, etc.).Outlets needed for O2, suction.At least three means of access.


• Control Room:

100 - 150 square feet.Easy access and communication to procedureroom.Operating console with Computers, monitors .


• There are numerous devices that aninterventional radiologist can employ during aparticular procedure.

• Each of these is often modified for the particularapplication.

Tools


• A catheter is a hollow flexible tube that can beinserted into a body cavity, duct or vessel.

• Catheters thereby allow injection of fluids.• The process of inserting a catheter is

catheterization.

Catheters:


• Catheters allow the interventional radiologist toaccess a specific area in the body from anotherentry point in the body.

• Angiographic catheters can be divided into flushcatheters and selective catheters.


• Flush catheters are typically used for aorticinjections and have multiple side holes near thetip to allow for a rapid high-volume injection toopacify the large diameter vessel.


• A "pigtail" catheter is a special multiple sidehole catheter that allows higher volumes ofcontrast to be injected.

• Selective catheters contain only a single endhole and have no side holes.


Angiographic catheters.A. Flush catheters.B. Selective catheters.Dr. Ahmed Alsharef Farah 30

• Better Torque Control.• Strength.• Radiopacity.• Flexible.• A traumatic Tip.• Low Surface frictional resistance for good

trackability over guide wire.

Ideal characteristics of catheters:


Parts of a catheter:

1. Hub.2. Body.3. Tip.


• The diameter of the catheter is measured inFrench (Fr) size: 3 Fr is equivalent to 1 mm.

• Most diagnostic catheters are 4 or 5 Fr.


Catheters can be classified depending on:• Side holes:

Single Hole.End Hole with side holes.Blocked end with side holes only.

Classification:


• Sizes:Abdominal: 60 - 80 cmThoracic or Carotid Arteries: 100 - 120 cm.Size depends on:

I. Age of the patient.II. Selective or super selective study.III. Size of the vessels.


• Ideal practice is to use the smallest diametercatheter feasible for any particular study tominimize the risk of arterial damage by theprocedure.

Note:


1. Diagnostic catheters:Used for Angiographs.

2. Guiding catheters:Used for Angioplasty.

Catheters can be broadly classified under thesegroups:


• Guiding catheters are like angiography cathetersonly difference is that guiding catheters aremore stiffer& firmas it carries Balloon catheters,PTCA wires and stent delivery system.


• Access site: Femoral/Radial.• Location of ostium.• Anatomy: Patient size/ diameter of aorta.• Equipment required: kissing/bifurcation

intervention.• Back-up.• Side holes.

Factors for catheter choice:


• Angioplasty catheters are specialized catheterswith a balloon placed near its leading end toallow for dilation of Stenosis.

• The balloon is inflated through a side port andtypically connected to a pressure gauge.

Angioplasty Catheters:


• The manufacturer will note on the packaging theballoon diameter, length, nominal pressure, andburst pressure.

• The nominal pressure is the pressure needed toachieve the stated diameter.

• The burst pressure is a recommendation by themanufacturer of the maximal inflation pressurebefore balloon rupture might occur.


Angioplasty catheters.A. The catheter contains one port through which a

guidewire is placed and another port for balloon inflation.

B. Close-up of inflated balloon.Dr. Ahmed Alsharef Farah 42

• Guidewires are metallic or plastic wires thatserve two general roles: exchange and guidancewithin a vessel or lumen.

• Not only can the guidewire be used during theexchange of the access needle to a catheter, butit can be used to exchange different catheters.

Guide Wires:


Guide wires.Dr. Ahmed Alsharef Farah 44

• Stents are metallic cylindrical devices that areplaced within a vessel or other lumen to providea scaffolding to decrease the likelihood ofrecurrent Stenosis.

• Stents can be made of bare metal or can becovered with a fabric (Covered stent or stentgraft).

Stents:


• A balloon-expandable stent is mounted on anangioplasty catheter.

• When that stent is positioned in the properlocation, the balloon is inflated, expanding thestent.


• Alternatively, self-expandable stents can beused. This stent is housed between two layers ofthin catheters. The stent is deployed byunsheathing the outer layer. The metal in a self-expandable stent prevent it from collapsing.

• Balloon-expandable stents are used whenprecise positioning is needed, such as at theorigin of a renal artery.


• However, balloon-expandable stents are notstayed expanded and not used in parts of thebody where extrinsic compression could occur(i.e., neck and extremities).


Stents.A. Left to right: two types of graft covered self-expandable stents

(stent grafts); a bare metal self-expandable stent in the center; and a pair of balloon stents.

B. Endovascular stent grafts for abdominal aortic aneurysm repair.Dr. Ahmed Alsharef Farah 49

• Various materials can be delivered through acatheter to purposely occlude a specific vesselor deliver a specific therapeutic agent.

Embolic Materials:


• Curled metallic wires with or without embeddedfibers called embolization coils are delivered bypushing the coil through a catheter with aguidewire.

• Polyvinyl alcohol (PVA) beads, ranging in sizefrom 50 to 1,000 μm, are often used for tumorembolization.


• Cyanoacrylate glue and other adhesives can beinjected for vascular malformations and otherindications.

• Yttrium 90 radioactive beads andchemotherapeutic agents combined with PVAparticles can treat liver neoplasms.


Embolic agents.A. Polyvinyl alcohol (PVA) particles.B. Embolization coils.C. Detachable vascular plug.Dr. Ahmed Alsharef Farah 53

• These are specialized instruments for ablatingtumors in the liver, kidney, lung, and bonepercutaneously.

• These devices are used to freeze (Cryoablation)or burn (Radiofrequency ablation andMicrowave ablation) tumors.

Percutaneous Ablation Devices:


• These devices include biopsy needles, vena cavafilters, drainage catheters, and venous accessdevices.


Radiofrequency ablation probe.A. Probe with electrodes retracted.B. Tip of probe with electrodes deployed. These are placed

directly into the lesion.Dr. Ahmed Alsharef Farah 56

Biopsy devices.Dr. Ahmed Alsharef Farah 57

The END


introduction to interventional radiology

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