MEDICAL IMAGING
What is a Radiologist?
Radiology
A Radiologist is a doctor who has undergone a 5-year specialist post-graduate training in diagnostic radiology (DR) and obtained the Fellowship of the Royal College of Radiologists (FRCR). A significant number of Radiologists obtained medical and surgical qualifications before embarking in a career in Radiology e.g Member of the Royal College of Physicians (MRCP) or Member of the Royal College of Surgeons (MRCS). Radiology is a recognised specialty within hospital medicine.
A Diagnostic Radiologist (DR) is a doctor who specialises in medical imaging to aid the diagnosis of certain conditions and assess treatment responses. Radiologists are fully trained, including the underlying physics, to use X-rays, fluoroscopy, nuclear scanning, ultrasound, CT scanning and MRI scanning. As the complexity of the technology becomes more advanced it is common in tertiary and quaternary hospitals that radiologists become more sub-specialised in specific areas of medicine e.g. a urogenital radiologist or a gastrointestinal radiologist.
Interventional Radiology (IR) is a sub-specialty of radiology, requiring further specialist training, aimed at treating medical conditions using imaging as guidance – it is often referred to as minimally invasive surgery.
What is Diagnostic Radiology?
Diagnostic Radiology
DR is a medical specialty that is concerned with diagnosing medical conditions using different medical imaging modalities which include fluoroscopy (x rays), ultrasound, Nuclear scanning, CT scanning and MRI scanning. Diagnostic radiology plays an integral part in the diagnosis of disease or injury. The exams often use radiation, at levels that have been determined to be safe, to create detailed anatomical images.
Examples of diagnostic radiology include: Radiography (X-rays) Ultrasound Computed Tomography (CT) Scans Magnetic Resonance Imaging (MRI) Scans Nuclear Medicine Scans
Diagnostic radiology can be used to identify a wide range of problems. Broken bones, heart conditions, blood clots, and gastrointestinal conditions are just a few of the problems that can be identified by diagnostic imaging. In addition to identifying problems, doctors can use diagnostic radiology to monitor how your body is responding to a current treatment. Diagnostic radiology can also screen for diseases such as breast cancer and colon cancer.
What is Interventional Radiology (IR)?
Traditionally open surgery has been the gold standard for the treatment of many medical conditions. However since the mid 90’s there has been a movement toward minimally invasive alternatives leading to the replacement of many open surgical procedures. Laparoscopic and robotic surgical techniques are now common place. However, Interventional Radiology (IR) is the ultimate minimally invasive surgical option that can treat a number of medical conditions through 1-2mm incisions often as a day-case with less post procedural pain and early recovery times. These techniques are typically in the setting of a day-case performed under simple local anaesthetic or intravenous sedation without the need for a full general anaesthetic
IR developed in diagnostic angiography in the 1960s, after Dr Sven-Ivar Seldinger described the Seldinger technique for access in 1953. Over the past decades there has been a massive expansion in the conditions treatable by IR due to the technical advances in medical device technologies and quality of imaging, IR is at the cutting edge of medical technologies and devices and became a recognised sub-speciality in Radiology in 2010.
Conditions treated by IR range from draining of fluid collections (abscesses, dilated kidneys, pleural effusions), opening up of blocked tubes (arteries, veins, bile ducts, ureters and others), stopping bleeding from any cause by occluding the vessels with embolisation, destroying tumours in the liver, lung, kidney by delivering local chemotherapy, embolisation or ablation techniques, minimally invasive treatments of thoracic and abdominal aneurysms and preoperative embolisation to improve the safety of surgery.
IRs pioneered the safe and high-quality procedures and standards for performing minimally invasive therapies, with a concentration on patient safety. IR’s are specialists of radiology, who have completed additional education and training in interventional radiology including radiation safety, radiation physics, the biological effects of radiation, injury prevention and clinical practice.
What is Ultrasound Scanning?
Ultrasound Imaging
Ultrasound (US) imaging uses high frequency sound waves which reflects differently of the internal body tissues allowing the computer to build up an image of whatever part of the body is being scanned.
US is dynamic, it is real time imaging, and quick allowing out patient scanning as a first line investigation for a number of medical conditions. It is very safe and can be used in pregnancy. It does not involve any ionising radiation.
US can also use multiple different probes designed to optimise imaging of certain areas and use sophisticated techniques to look at blood flow within vessels and lesions to help characterise and identify narrowing’s within vessels. These techniques are known as Duplex or Doppler scanning. Use of newer techniques including ultrasound contrast and elastography have added a new dimension to the diagnostic ability of ultrasound imaging.
US is ideal to be used as a screening test for abdominal aneurysms (AAA), assessing carotids and peripheral arteries and veins, assessing blood flow in organs and imaging small parts e.g. scrotum and testes, thyroid. Other common uses include abdominal, musculoskeletal and gynaecological imaging.
What is CT Scanning?
Computer Tomography (CT) imaging uses ionising radiation to create a complete internal picture of the body that can be viewed in multiple planes and often even in 3D/4D. The technology has improved enormously over the past few decades meaning that one can scan the whole body in less than 10 seconds with very high image quality. You lie on a table that passes through a gantry “doughnut” which contains the detectors to build up the image. Often you need preparation for the scan, which involves drinking a special contrast the night before and 1hr prior to your scan. This allows visualisation of the bowel. You will also typically have a small cannula placed to administer additional contrast into a vein to show the blood vessels and internal organs in more detail.
CT scanning is evolving all the time and all the private institutions have the modern multi-detector multi-slice latest generation CT scanners. CT scanning offers a non-invasive way of examining all the internal structures and allows characterisation of any abnormalities seen. It can then be used to guide a tissue biopsy or potential ablative therapies with procedures being performed under local or general anaesthesia within the CT department. It is used widely in the field of oncology and surgery for diagnosis and follow-up of treatment.
What is Fluoroscopy Imaging?
Fluoroscopy
Fluoroscopy is used where real-time X-Ray examination of the patient’s body is required. Some of the uses include positioning of orthopedic implants during surgery, catheters and pacemakers, viewing the movement of contrast agents, such as barium, through the body and studying the movement of parts of the body.
As with conventional radiology, an X-ray beam is passed through the body but instead of being registered on film, the image is displayed on a fluorescent screen. Modern versions digitize the image using ‘flat panel’ detector systems, which reduce the radiation dose required. The image is then intensified digitally and displayed on a screen or recorded for more detailed analysis later.
Contrast agents are used to make organs in the body visible on the images. They can be given by injection into the blood stream or via tubes into internal organs. Barium products, taken orally, are used for examining the gastro-intestinal system. Fluoroscopy is used in many types of examinations and procedures, e.g. barium X-rays and enemas to view movement through the gastro-intestinal tract
As with all X-ray procedures, fluoroscopy exposes the patient to a small amount of ionising radiation. The exact amount varies according to the procedure. This in turn is associated with a low risk to the patient. Doctors and manufacturers know about these risks and do all they can to minimise radiation dose, keeping the exposure time to a minimum. These risks, however, are remote and experts consider them to be far outweighed by the benefits of an accurate diagnosis and treatment. Nevertheless, women should always inform their Doctor or X-ray technologist if there is any possibility that they are pregnant.
What is Magnetic Resonance Imaging (MRI)?
MRI is a modern medical imaging technique invented in 1977 and has developed enormously since then with sophisticated scanners able to image the whole body using strong magnetic fields and radiowaves. MRI does not involve ionizing radiation like CT scanning and gives exquisite images of the internal organs, especially the soft tissues. It complements CT imaging.
New sequence developments now allow functional information to be obtained so that not only can we now identify abnormities we can also determine function e.g likelihood of cancer, amount of oxygen usage. MRI scanners are often known depending on the size of the magnet that they contain e.g 1.5T or 3T scanning.
During an MRI scan, you lie flat and are moved into the scanner. Depending on the part of your body being scanned you will move into the scanner either head or feet first. A radiographer using a computer operates the scanner. MRI scans often involve some noise and can take between 30-60 minutes to complete.
MRI scans work by using a proton at the centre of a hydrogen atom contained within water molecules in the body (water molecules consist of hydrogen and oxygen atoms). Protons are like little magnets and are very sensitive to magnetic fields. When you lie in the scanner magnet these protons all line up, short bursts of radio-waves knock these out of alignment and when they are turned off the protons realign sending out a signal, which generates the image of the body. Early pregnancy and patients with pacemaker implants need special advice before an MRI.
