Medical Imaging
Medical imaging plays an important role in sarcoma care. Exams such as MRI, CT scans, X-rays, ultrasound, and PET/CT are used at different stages to help diagnose the disease, plan treatment, and monitor recovery.
This section is designed to help you understand why imaging is used, what the different tests are, and how they support your care. The information is written for patients and families, with the goal of helping you feel informed and comfortable asking questions throughout your journey.
Introduction
Medical imaging refers to tests that create pictures of the inside of the body, such as MRI, CT scans, X-rays, ultrasound, and PET/CT. In sarcoma care, imaging is essential for diagnosing the disease, determining its extent, guiding procedures such as biopsies, planning treatment, and monitoring how the cancer responds to therapy over time.
Imaging Across the Cancer Journey
Diagnosis and Staging
Imaging is often one of the first steps when a sarcoma is suspected. These tests help doctors:
- Identify the presence of a tumor
- Determine its size, location, and relationship to nearby structures such as muscles, bones, nerves, and blood vessels
- Assess whether the cancer has spread to other parts of the body
This information is critical for confirming the diagnosis, staging the disease, and planning the most appropriate treatment approach.
Imaging-Guided Biopsy
A biopsy is needed to confirm the diagnosis of sarcoma. When tumors are located deep in the body or near important structures, imaging guidance is often used to safely and accurately guide the biopsy needle into the tumor. This helps ensure that the tissue sample is taken from the correct area while minimizing risks.
Treatment Planning and Guidance
Medical imaging is used to guide treatment in several ways:
- In radiotherapy, imaging helps define the exact area that needs to be treated while protecting nearby healthy tissues
- During surgery, imaging may be used to guide the placement of surgical hardware in certain situations
Accurate imaging allows treatments to be tailored to each patient’s specific anatomy and tumor characteristics.
Assessing Treatment Response
After treatments such as radiotherapy given before surgery, imaging is often repeated to evaluate how the tumor has responded. Doctors may look for changes in tumor size or appearance to help assess whether the treatment has been effective and to guide next steps.
Post-Operative Assessment
After surgery, imaging may sometimes be used to check for early complications, such as infection. Not all patients require routine imaging immediately after surgery; this depends on the clinical situation.
Surveillance and Long-Term Follow-Up
Following completion of sarcoma treatment, imaging is commonly used for surveillance. These follow-up scans are done at regular intervals to look for any signs that the cancer has returned or spread to another part of the body. When sarcoma spreads, it most often goes to the lungs. For this reason, many patients have regular chest imaging tests, such as CT scans or chest X-rays, during follow-up. Detecting a recurrence early may allow for more timely and effective treatment.
Conclusion
Once an imaging exam is completed, it is interpreted by a radiologist, a physician specialized in medical imaging. The radiologist prepares a report describing the key findings and sends it to the treating physician. The treating physician then discusses the results with the patient and explains what they mean in the context of their overall care.
Introduction
Several different imaging techniques are used in sarcoma care. Each technique provides specific information and may be used at different stages of diagnosis, treatment, and follow-up. The choice of imaging depends on the type of sarcoma, its location, and the clinical question being asked.
-Magnetic Resonance Imaging (MRI)
MRI uses a strong magnetic field to produce detailed images,. In sarcoma care, MRI is particularly important for:
- Assessing the local extent of a sarcoma
- Planning radiotherapy and surgery
MRI provides very detailed information about how a tumor relates to nearby muscles, bones, nerves, and blood vessels. It is particularly useful at evaluating soft tissues and bone marrow (the tissue inside bones). MRI does not use ionizing radiation. Multiple sets of images are taken during an MRI examination, which can make the exam a bit long. It is important to stay still during the exam because movement can cause artifacts (blurring) on the images. Contrast material (dye) is often, but not always, injected into a vein during an MRI examination to help highlight tumor tissue.
-Ultrasound
Ultrasound uses sound waves to create real-time images. It is commonly used to:
- Evaluate superficial soft tissue masses
- Help distinguish between cystic (fluid-filled) and solid lesions
- Guide biopsies of accessible tumors
Ultrasound is widely available, does not involve radiation, and can often be performed relatively quickly.
-Radiographs (X-rays)
Radiographs use a small amount of radiation to create images. In sarcoma care, they are most commonly used to:
- Evaluate bone tumors
- Detect lung metastases
X-rays are often used as an initial imaging test and may be followed by more advanced imaging if needed.
-Computed Tomography (CT)
CT scans use X-rays sent from many directions by a moving, donut-shaped machine. A computer then puts these images together to create many thin slices of the body. CT is commonly used to:
- Image the chest to look for spread of disease to the lungs at diagnosis and during follow-up
- Evaluate the abdomen and pelvis when relevant, depending on sarcoma type and location
- Assess bone involvement
CT scans are fast and widely used, but they do involve exposure to ionizing radiation. Contrast material (dye) is sometimes used during CT scans to better see organs and blood vessels, particularly when imaging the abdomen or pelvis.
-Positron Emission Tomography with CT (PET/CT)
PET/CT combines two types of imaging: one that shows how parts of the body are working (functional imaging) and one that shows the body’s structure (anatomical imaging). A small amount of radioactive tracer is injected into a vein. This tracer collects in areas with higher metabolic activity in the body and helps highlight them on the images. In some patients with sarcoma, PET/CT may be used to:
- Evaluate the extent of disease
- Assess response to treatment
- Clarify findings seen on other imaging tests
PET/CT is not required for all patients and is used only in certain clinical situations.
-Contrast Agents
Contrast agents are sometimes used during CT or MRI exams to improve visualization of tissues and blood vessels. Contrast can help better define tumor margins, internal characteristics, and relationships to surrounding structures. The healthcare team evaluates the benefits and risks of contrast use for each patient, including kidney function and history of allergies.
-Imaging-Guided Bone Biopsies
When doctors suspect a bone sarcoma, a biopsy is often needed to make a diagnosis. Imaging guidance, most commonly a CT scan, helps guide the needle to the correct area of the bone. During the procedure, CT images are taken several times to make sure the needle is moving in the correct direction and to help reduce the risk of complications. Once the needle is placed in the suspected tumor, small samples of tissue are collected and sent to a pathologist, a doctor who examines tissue under a microscope, to determine the diagnosis.
-Imaging-Guided Soft Tissue Biopsies
When doctors suspect soft tissue sarcoma, a biopsy is often needed to make a diagnosis. Imaging guidance, most commonly ultrasound, can help guide the needle to the correct area of the tumor. During the procedure, ultrasound provides real-time images to make sure the needle is moving in the correct direction and to help reduce the risk of complications by avoiding nearby structures such as blood vessels and nerves. Once the needle is placed in the suspected tumor, small samples of tissue are collected and sent to a pathologist, a doctor who examines tissue under a microscope, to determine the diagnosis.
Conclusion and Additional Resources
Medical imaging can feel complex, but each test plays a specific role in sarcoma care. If you have questions about an imaging exam or its results, your healthcare team can provide you with the necessary information.
Reliable patient-friendly resources include:
- Canadian Cancer Society
- Canadian Association of Radiologists
- American College of Radiology
- National Comprehensive Cancer Network
These organizations provide information to help patients better understand medical imaging and cancer care.