X-rays, CT scans, MRIs, mammograms and ultrasound images are well-known diagnostic tools for health care professionals.
But when scans are taken of patients and sent off, where do they go, and who makes a diagnosis?
The answer often happens in a dark room with the overhead lights turned off.
In his tiny office, his face lit by three screens, flickering grey images bounce off the eyes of Dr. W. Fin Hodge as he examines a section of a patient’s anatomy by scrolling the wheel of his computer mouse.
With each click, different slices of the man’s leg appear in anatomical detail.
At times, the layers move so fast, it looks like stop-motion video of a slithering primordial creature.
He sifts through different angles from an MRI and settles on one picture.
Hodge adjusts the contrast and begins to explain the situation.
The patient is a man in his early 50s. His history: Knee pain.
He examines several ligaments (dark fibres, all intact), before focusing on a too-thin layer of cartilage near the medial femoral condyle.
“This person has a tiny little fragment of (loose) bone that’s sitting in this joint space, and so every time he walks on that, it’s moving around in there and it does damage to the cartilage.”
There are also indications of osteophytosis, outgrowths of bone tissue that forms around damaged joints.
Though the image looks big on the screen, the area of damage is actually just one to two millimetres in length.
“As a radiologist, you need to know the anatomy of the structures you’re looking at because you need to know what normal looks like, and you really need to know the physics of the modality you’re using.”
Although the osteoarthritic degeneration of the patient’s knee is advanced for his age, Hodge says that there are injection and surgical treatments that will be used long before a knee replacement would be considered.
Hodge, based in the Jim Pattison Outpatient Care and Surgery Centre in North Surrey, is a type of doctor some patients will never see – an interpreter of medical imaging.
He has 13 years of post-secondary education, including four years for a science degree, four years of medical school and a further five years (one intern) specializing in radiology.
He’s also got a battery of different imaging modalities – a term that pops up repeatedly when you talk to radiologists – to help with his diagnoses.
X-rays, most often of the chest, are the bread-and-butter work for radiologists.
The process hasn’t changed much since the late 19th century, where ionizing radiation is sent through the body onto detectors. (At times, film is still used at the SMH, but radiologists mainly use Digital Radiography (DR), where the picture is created on a phosphor plate and then digitized by a laser image reader before being sent to a computer screen).
The ghostly images are familiar, with a gradient of increasing darkness as the matter gets less dense: Bones in white (they’re too hard for the weak X-rays to pass through to reach the “film”), muscle in light grey, fat in dark grey and fluids or air (such as lungs) in black.
CT scans (computed tomography) also use X-rays, but produce multiple images from different angles. Hodge describes it as a fan beam of X-rays that captures a larger volume of information as it spins around the patient.
Ultrasound scanners use high-frequency sound waves to produce images. Results-wise, the same rules apply for ultrasound as for X-rays.
“Bone reflects sound, whereas fat absorbs sound,” making bones lighter in the images,” Hodge explains.
Then there is the most modern of modalities, the MRI, which stands for Magnetic Resonance Imaging.
“I won’t go into too much detail,” Hodge begins without irony, “but essentially we align the protons of the body in one direction along the main magnetic field and then we can manipulate those with radio frequency pulses. And the radio frequency signal that is emitted by those protons as they relax back to their state, we can record, and through some complex transformations that are done by the computer, we end up with MRI images.”
Each modality has its strengths and weaknesses, and part of a radiologist’s job is to determine which modality would be best suited for the patient’s problem – though usually X-rays come first, especially in emergency cases.
There are 10 radiologists shared between the Surrey Memorial Hospital and Jim Pattison Outpatient Care and Surgery Centre – scans at the latter are given to more mobile patients.
Radiology was always a diagnostic specialty, but imaging interpreters are getting more involved in the therapeutic side of medicine.
With the increasing sophistication in imaging, they can now see and do more.
“In some cases, we can provide treatment,” says Dr. Del Dhanoa, a radiologist specializing in interventional therapy in his office at SMH.
He gives some common examples of image-guided treatments he performs:
• Guiding targeting markers (metallic beads) put into prostate glands for radiation treatment;
• Inserting stents or tubes to help cancer patients bypass obstructions, often in the liver;
Photo by Boaz Joseph: Dr. Del Dhanoa, seen through a CT Scanner at SMH.
• Inserting catheters used to treat infections;
• Guiding renal access for catheters in dialysis patients; and
• Hybrid diagnostic and interventional therapies (including guiding for biopsies) at the Breast Health Clinic, where a new system aims to provide triple assessment (mammogram and/or ultrasound, physical exam and tissue sample) in one visit.
“Generally (the modalities are) a combination of fluoroscopy and CT scanners, but we can also use ultrasound – it depends on the situation,” says Dhanoa.
(Fluoroscopy sends X-rays through the patient onto an image intensifier that allows real-time visuals on a screen. It allows radiologists to watch, for example, the actions of a patient’s esophagus and stomach as they swallow a liquid).
Dhanoa says interventional radiology has blossomed recently, making for less invasive treatments for patients.
“Rather than having a six-inch scar from a surgery, you have a three- or four-millimetre puncture hole.”
The result: Shorter stays and lower costs to the medical system – as well as more interaction with patients.
Next week: Box therapy
How a wrist was saved by the simplest of tools
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