What is Interventional Radiology?
Interventional Radiology is a subspecialty of radiology in which radiologists treat various conditions using an imaging modality to guide the procedure. In most cases the procedure involves guiding a needle or catheter to a specific location through a puncture in the skin. The most common interventional procedures performed are pain blocks, drainage procedures and vascular procedures which are all discussed below.
The Lake Imaging radiologists performing interventional procedures have a special interest in the technique which ensures the highest standards are maintained. Before the examination, patients are interviewed by the radiologist and in the case of vascular intervention, by the nurse. Information about the procedure is conveyed and any questions answered. A consent form must be signed prior to an interventional procedure.
Pain Blocks (including nerve root blocks)
Pain blocks are usually performed under fluoroscopic or CT guidance and occasionally with ultrasound. Patients with pain due to inflammation in a ligament or joint or irritation of a nerve root can benefit from this procedure. A facet block is a specific type of pain block targeting inflamed facet joints in the spine. Facet joints are joints in the spine that lie behind the main body of the vertebrae. Other joints that can be treated include the shoulder, sacroiliac and hip joints. Patients with inflammation in the foot (plantar fasciitis) can be similarly treated. Local anaesthetic is infiltrated into the skin at the site of puncture. A small gauge needle is inserted into the painful joint or adjacent to the irritated nerve. A combination of a local anaesthetic and a long acting steroid with anti-inflammatory properties is injected to relieve the pain. In the case of a 'frozen shoulder', the distention of the joint due to the injection is thought to assist in improving joint mobility. The image to the right is an example of CT guided needle placement for a pain block.
Preparation: There is no specific preparation.
Drainage procedures
Percutaneous drainage of fluid collections usually from the thorax, abdomen or pelvis or from cysts in the kidney, liver, breast etc. 'Percutaneous' means via a puncture through the skin. After injection of local anaesthetic into the skin, a small to medium gauge needle is inserted into the cyst or collection under aseptic conditions. In some cases the cyst or collection is simply drained by aspiration through this needle as in the drainage of breast cysts. In large infected collections particularly in the abdomen or pelvis, a flexible 'pigtail' catheter may be inserted into the collection using guidewires and dilators to assist in the placement of the catheter.
This catheter is left in place and attached to a drainage bag to enable complete resolution of the collection. Material obtained from the aspiration is sent for pathology tests to identify infecting organisms or sometimes to check for abnormal cells. Some large cysts of the kidney may be treated with an alcohol injection after the drainage. The alcohol irritates the cyst lining and helps prevent recurrence.
A nephrostomy is a special type of drainage procedure which involves the insertion of a 'pigtail' catheter into the collecting system of a kidney to relieve an obstruction. A needle is inserted into the dilated kidney and the position confirmed. A guide wire is inserted into the kidney and dilators used to enlarge the tract. The pigtail catheter is inserted over the guidewire and secured in place. A drainage bag is connected to the catheter.