MRI, X-Ray, CT Scan, PET, Sonogram
By Deborah Jeanne Sergeant
If you’re sick or injured, you may receive imaging from a healthcare provider, depending upon what’s going on. But what type of imaging you receive differs for many reasons.
“Each type of imaging is designed to look at specific structures,” said Alicia Rayder, certified family nurse practitioner and director of radiation and CT services at Hematology-Oncology Associates in East Syracuse. “An X-ray, for example, is excellent at showing bones and can quickly identify fractures, arthritis or lung infections. It is fast, widely available, and often the first step when someone presents with pain or injury.”
Confusion often enters when an ultrasound may give some but not all the information a provider needs, so a CT scan is necessary, for example. Sometimes the standard practice type of imaging for a case does not reveal sufficient information for providers to diagnose and form an effective treatment plan. Then providers may turn to a different type of imaging.
“Doctors often start with the simplest, safest and most targeted test based on a patient’s symptoms,” Rayder said. “If that first image answers the question, no further imaging is needed. If it raises new concerns or reveals an area that requires closer evaluation, additional imaging helps clarify the diagnosis.”
In general, X-ray is the most commonly performed type of imaging exam in medicine by volume as it is inexpensive and provides a good look at things such as bones. X-ray is good for a two-dimensional image. But some things aren’t as visible on X-ray.
“Ultrasound uses sound waves rather than radiation and is especially useful for evaluating soft tissues, organs, and blood flow,” Rayder said. “It is commonly used to assess conditions such as gallstones, blood clots, pregnancy, or thyroid nodules. In oncology, ultrasound is often used to further evaluate a mass or assess nearby lymph nodes. For example, in breast cancer care, ultrasound may help distinguish a solid mass from a fluid-filled cyst and guide biopsies when tissue sampling is needed.”
A CT scan, MRI or PET scan enables greater detail and is often used for more complex issues with bones, organs and blood vessels. Rayder said a CT is often used in emergency settings, and sometimes CT is used for staging for cancer care to look
at the extent of the disease’s progression.
“MRI provides exceptional detail of soft tissues, including muscles, ligaments, the brain and spinal cord, and is often used when precise visualization is critical,” Rayder said. “A PET scan shows how active cells are in the body, helping doctors identify areas where cancer may be growing or spreading.”
Physicians work with radiologists who read images and together they develop answers for patients, such as a diagnosis and treatment plan. Rayder said that providers use imaging for assessing the patient’s progress and changes over time. Selecting the right type of imaging makes a difference in patient care.
“Using the right imaging test at the right time allows cancer care teams to make informed decisions and tailor treatment to each patient,” Rayder offered as an example. “While undergoing multiple scans can feel overwhelming, each one provides valuable information that guides care with greater confidence and precision.
“Think of it like taking pictures: a wide-angle photo captures the full scene, while a close-up reveals important details. Using the right image at the right time helps doctors avoid unnecessary testing while ensuring nothing important is missed”
X-Ray, CT Scan, PET, MRI
Physician Adam Zinkin, chief of diagnostic imaging at Rochester Regional Health, explains how medical imaging works:
X-rays
“X-rays are the oldest and most widely recognized form of medical imaging. They work by passing a small amount of ionizing radiation through the body. Denser structures such as bones appear white on an X-ray image, while less dense tissues appear darker.
Computed tomography scanning (CT scanning)
“CT scanning builds on x-ray technology to create more detailed images. A CT scanner rotates around the body and allows images to be seen in cross-sectional views. These images allow doctors to examine organs, blood vessels, and soft tissues with much greater clarity than standard X-rays. One of the main drawbacks of CT scans is their higher radiation exposure compared to standard X-rays, which is why doctors weigh the benefits carefully before ordering them, especially for children.
Magnetic resonance imaging (MRI)
“MRI takes a completely different approach. Instead of radiation, MRI uses strong magnetic fields to produce images. This technique is especially effective for visualizing soft tissues such as the brain, spinal cord, muscles, and ligaments. MRI scans can reveal subtle differences in tissue structure, making them essential for diagnosing neurological disorders, joint injuries, and certain tumors. Another advantage is that MRI does not expose patients to ionizing radiation. However, MRI scans take longer, are more expensive, and require patients to remain still in a confined space, which can be uncomfortable, particularly for claustrophobic patients, though MRI technologists are typically quite adept at assisting claustrophobic patients through these exams.
Ultrasound
“Ultrasound imaging relies sound waves rather than radiation or magnets. These sound waves bounce off internal structures and create real-time images that doctors can observe as they are generated. Ultrasound is often used to assess fetal development during pregnancy. It is also widely used to examine the heart, blood flow, and abdominal organs. Because ultrasound does not utilize ionizing radiation, and is relatively inexpensive, it is often used as a first-line imaging tool. Its limitations include lower image resolution compared to MRI or CT scans and reduced effectiveness when imaging areas are blocked by bone or air.
Positron emission tomography (PET)
“PET scanning, focuses on how tissues function rather than how they look. Patients receive a small amount of radioactive tracer, which accumulates in areas of high metabolic activity. These areas appear brighter on PET images, making the technology particularly useful in cancer diagnosis and treatment monitoring. PET scans can identify disease at an early stage, sometimes before structural changes become visible on other imaging tests. Because PET scans are costly and involve radioactive materials, they are usually reserved for specific clinical situations and are often combined with CT scans for greater accuracy.”