What is the difference between a CT and a PET-CT scan?


CT and PET-CT scans are very common procedures that doctors administer every day to help localize their examination and to provide the most thorough diagnosis. Both procedures contain varying, minimal risks but can provide huge benefits for patients that need a more in-depth examination and specialized treatment.

What is a CT scan?

A CT scan or a Computed Tomography scan is a medical procedure that uses x-ray radiation and fascinating computer technology to create cross-sectional images of the body’s organs and tissues. CT scans can also be called CAT or Computed Axial Tomography. CT scans take helical images of the examined part of the body which produces better 3-dimensional imaging. The better the image, the better the diagnosis your doctor can make. CT scans are particularly useful in the examination of tissues, cancer staging, and determining vascular disease.

What is a PET-CT scan?

A PET-CT scan or Positron Emission Tomography is a medical procedure similar to a CT scan but PET-CT scans are commonly used in determining the difference between healthy and diseased tissue. Using nuclear medicine these exams allow particular focus on oncological symptoms in the brain and heart as well as any vascular or tissue abnormalities.

What are the procedures like?

The biggest difference between a CT and a PET-CT scan is the machinations of the procedure. There are varying states of discomfort between both procedures, but both are relatively painless and easy to complete for any patient.

A CT machine looks like a large tire with the patient placed inside the “hole.” The patient is placed on the examination table and will be administered contrast material through the mouth or intravenously. The feet will be the first to enter into the machine and the body will be slowly moved into the chamber. The procedure lasts approximately 10-30 minutes. Patients typically report that they hear a slight whirring sound which is the machine rotating around them gathering imaging. The doctor will able to speak to you and you will be able to respond.

A PET-CT scan is similar to a CT scan in some ways but the biggest difference between the two is the instructions prior to the exam. Most doctors and facilities will request that a patient not eat at least 4 hours prior to the scan and to drink lots of water. The exam also lasts slightly longer at about 30-45 minutes. Contrast material is commonly used as well and will either be  administered through an IV or by inhalation. If the PET-CT scan is being administered because of possible heart disease, the patient will often be asked to perform a stress test. The body will be examined at rest and during exercise in efforts to determine any cardiovascular problems. You may also hear a buzzing or clicking sound during this procedure.

Which procedure is more painful?

Both procedures have a minimal amount of pain and discomfort. The most common complaint is concerning the IV injection site or a claustrophobic feeling. But the contrast material is necessary for properly determining the condition of tissues and veins as well as highlighting possible cancerous cells. Furthermore, the body moves through the machine. It only covers the area that will be examined — it does not encapsulate the entire body.

Are there any risks?

Doctors and imaging facilities have been able to minimize the risks surrounding these procedures to practically nothing. Both a CT and PET-CT scan use small amounts of radiation to image the examined area. If you are pregnant or could possibly be pregnant, you should let your doctor know. There is no medical evidence that the amount of radiation is dangerous for an unborn child. But if there is another safer method to examine, your doctor can help you understand your options. Also if you have any implanted devices, artificial body parts or features such as hearing aids or dentures, talk to your doctor about what needs to removed for the procedure.

Ready to make your appointment? You can use our request an appointment form online or just call us at 504-883-8111.

The History of Medical Imaging

The first X-RayMedical imaging is a form of technology that has revolutionized the medical field in the past century.  With these new innovations, doctors were able to elevate the standard of practice and the experience of the patient. Now, areas of pain or trouble can be non-invasively examined and treatment can begin without the patient even needing to go under. But when did the innovation of medical imaging begin?

Read below to take a trip down memory lane and find out how the medical field and the technology industry have been working together to build a better, healthier world.

Röntgen performs X-Ray in 1895

Professor Wilhelm Röntgen accidentally discovers the ability to look through the skin and see the bones of the body while performing experiments on another project. While working with a cathode ray generator, he noticed an image that was left when the cathode rays came into contact with the vacuum tube. He performed the first X-ray on his wife’s hand and even gave the technology the name we use today, calling this discovery “X” rays because they were unsure what exactly they were. This invention was eventually standardized by William Coolidge and his X-ray known as the “Coolidge tube” is what all modern X-ray machines are based from.  The first X-rays required at least 11 minutes of exposure to produce a quality image. Now X-rays take only a few seconds and they use about 2% of the radiation amount seen in the early 20th century machines.

Scientists Use Ultrasounds in the 1960s

The basics of sonar had been discovered and utilized during World War II as a form of maritime warfare. In the early 1960s, scientists discovered that sending sound waves into the body would bounce off the internal structures and then returned to the ultrasound machine to be reformatted into images for doctors to see. This allowed doctors to non-invasively search for tumors and other growths.

Damadian Discovers MRI in 1970

Dr. Raymond Damadian discovers that different animal tissues emit different signals, as well as that cancerous tissues, take much longer to return the signal sent through them. This is the basis for magnetic resonance imaging. In 1977, Dr. Damadian created the first full-body MRI machine which he named the “Indomitable.”

Hounsfield Invents CT Scans in 1972

The 1970s showed the first instance of computer technology mixing into the medical field with Sir Godfrey Hounsfield’s invention of the CT machine. He theorizes that you could see into an object if you took X-rays from different angles of the object through a machine that would appear as “slices” which could then be put together to form an image. With his idea, he formed the first “axial tomography” machine which we now know as the CT machine. In 1979, he received the Nobel Prize in Medicine and was later knighted by the British Royal Family.

Since then, all of these machines have entered into the digital age and are now updated with the latest technology available. This means that there is less potential risk for patients as well as a greater ability to diagnose and treat.

Looking for medical imaging in Louisiana? At Doctors Imaging, we’re Radiologists concerned with patient care. Meet our Radiologists or request your next medical impaging appointment online.

A Look at Doctors Imaging’s Medical Equipment

At Doctors Imaging, we like to provide the best service, staff, and equipment along with the best price for our patients. We believe that everyone should have access to these machines so that they can be confident in their treatment plans and knowledgeable about their health conditions.

We have a 3T MRI and we offer an open MRI for the patients that feel uncomfortable or claustrophobic in the traditional MRI. A 3T MRI is the most powerful MRI machine for every part of the body and we are the region’s first freestanding center to offer its capabilities. There are other facilities and hospitals that use the 1.5T MRIs, but at Doctors Imaging, we want the most powerful equipment and since insurance companies usually charge the same price no matter what the equipment is, you can have the best equipment and images for a lower price than you would pay at a hospital.

In addition to our MRI machines, we also offer the low-dose CT machine, a powerful CT machine with the lowest radiation settings possible. We use the Toshiba Lightning Aquillon CT scanner with Adaptive Iterative Dose Reduction 3D software. With this technology, multiple “slices” or pictures of the examined area can be provided to doctors allowing them to see further and deeper into the body so they can give a thorough diagnosis and treatment plan. This machine allows for up to 75% reduction rate in radiation as opposed to many other CT machines on the market. We understand that radiation exposure is a concern for many of our patients which is why we dedicate ourselves to providing the best and safest care possible.

At Doctors Imaging, we also provide digital X-rays so there is less radiation exposure from this as opposed to the traditional X-ray machines. We also offer 3D ultrasounds so that expectant mothers, as well as medical patients, can have the most in-depth and detailed images of their babies and bodies available to them.

We want people to know that if you need a medical imaging procedure, you are not required to go to a hospital. Instead, you can come to Doctors Imaging in Metairie and have an immediate appointment, almost no waiting time, fast results and a great affordable price.

Visit our Make an Appointment page or call 504-883-8111 for the best days and times for your imaging procedure.  

The Art Behind a CT Scan

Who know peering into the human body could be so mesmerizing? Dr. Kai-hung Fung is not only a Hong Kong-based radiologist, but he is also known as an artist. While developing 3-D images that allow surgeons to visualize complex anatomies before surgery, Dr. Fung discovered that CT scans are not just black and white.

Using CT scans that show slices of organs at a different depth, Dr. Fung was able to stack the slices into a single image and develop a method to indicate the changes in depth with contour line that resemble those on a topographic map. Human anatomy is beautiful, and a CT scan of a female nose can resemble a beautiful, exotic flower.

Since then, Dr. Fung’s art career has blossomed. His amazing diagnostic images have been awarded, exhibited and published. His CT and MR scans are more than just psychedelic images, they are “4-D visualizations” that help surgeons visualize the changing perspectives and relative relationships of various anatomical structures. Think of “Fantastic Voyage” but this is not science fiction.

This accidental discovery has changed the way we will view CT and MRI scans forever.