Computed tomography (CT) and positron emission tomography (PET) scans are imaging tests designed to enable your radiologist and referring clinician to study internal organs and structures. If you have an appointment to receive a CT or a PET scan, you may have questions about why one was ordered over another. In some cases, you may be due to get a CT/PET scan, and wonder why the tests have been combined. To answer some questions, let’s look at these two scans, separately and together.
Computed Tomography
CT is a sophisticated technology that provides detailed cross-sectional images of the organs, muscles, bone, lymph nodes and blood vessels. By capturing images from varying angles, CT is able to provide multidimensional composites of the area being studied for greater accuracy than traditional x-ray. Because of its speed and detail, CT is a go-to test to examine internal injuries, diagnose disease, and plan treatment.
CT is typically used to diagnose and assess:
Injury to or disease of internal organs
Spine and bone fracture, damage or disease
Vascular disease, damage and blockage
Signs of stroke and assessment of damage
Infection
Excess fluid
Tumors, cysts, stones
Cancers, particularly of the lungs, liver, pancreas, spleen and bones
CT and Cancer
CT’s ability to capture even small tumors as well as the blood vessels feeding them makes it a valuable investigative tool to diagnose cancer, determine if and where it has spread, stage treatment, and check for possible recurrence. CT can also be used to assess a tumor’s reaction to therapy so the efficacy can be monitored.
Positron Emission Tomography
A PET scan is a nuclear medicine imaging test that creates visuals of organs and tissues at work, so their function can be examined. PET utilizes a tiny amount of injectable radioactive material to localize diseased cells so they show up on a specialized gamma camera. Diseased cells, particularly cancer cells, soak up the material more readily than healthy tissue, making PET an important test for discovering certain diseases or disorders that may not show up on other imaging tests. By being able to image molecular activity and crucial processes as they happen, PET is able to assess things like blood flow, oxygen use, glucose metabolism, and organ or system dysfunction. The radiotracer’s ability to highlight cancer enables a PET scan to help diagnose cancer and specific heart and brain diseases, as well as monitor treatment.
PET is often used to diagnose and assess:
Tumors (benign or malignant) affecting the brain, breast, thyroid, lungs, pancreas, colon, musculoskeletal system and other areas
Lymphoma and melanoma
Coronary artery and heart disease
Signs of heart attack
Seizures/epilepsy, dementia, and other brain disorders
PET scans may be performed more than once to investigate:
Whether cancer has metastasized to other areas of the body
The effectiveness of treatment
Cancer recurrence
Damage after a heart attack or stroke
Ongoing brain abnormalities
Which is More Accurate: a PET Scan or CT Scan?
CT provides more detailed images than PET, but PET’s ability to turn cellular changes into highly visible “hot spots” can increase the likelihood of finding problems like cancer early in their course. So, which test is best depends on the area being studied and the type of disease or dysfunction your doctor suspects may be present. Both tests are painless and take only about 30 minutes to complete. CT usually involves an injection of contrast dye to enhance details. PET requires an injection of radioactive material.
PET/CT Scan
A PET/CT scan combines the enhanced imaging detail of CT with the functional information and early cell change capture of PET. Performed at the same time with the same machine, PET/CT is more accurate than these tests performed separately, and able to produce both 3D and moving images to diagnose, evaluate and/or monitor:
Many types of cancer
Evidence of metastasis
Effectiveness of cancer treatment
Cancer recurrence
Cellular activity, metabolism and tissue viability
The effects of a heart attack
The need for angioplasty or coronary artery bypass surgery
Brain irregularities, cognitive decline, and other central nervous system disorders
While not all tumors absorb the injectable radioactive material, the ones that do reveal whether they are malignant or benign with great accuracy. By being able to scrutinize changes and abnormalities at a cellular level, your doctor and radiologist can localize irregular, cancerous or damaged tissues to diagnose disease, stage treatment and monitor the success of therapy.
RAO for CT, PET and PET/CT
With 50 years of diagnostic and interventional treatment experience, RAO is fully accredited in Computed Tomography and Positron Emission Tomography by the American College of Radiology for accuracy, safety and best practice standards. Our team of Board-certified radiologists includes doctors who are fellowship-trained in diagnostic imaging, nuclear medicine, neuroradiology, vascular and interventional radiology and other areas of specialization. We are committed to the highest level of accuracy, efficiency and compassion during every level of care.
