PET CT Scan and ultrasound scan are two types of diagnostic imaging used to evaluate abnormality in the body. Both are non-invasive procedures meaning they do not involve any type of surgical procedure. The PET CT scan is a more advanced imaging modality in comparison to ultrasound scan because it utilizes a radioactive tracer in evaluation of abnormality. PET CT scan is more expensive but another advantage of the PET CT scan is that it provides enhanced detail in evaluation of body systems and it can even evaluate cancerous conditions at a metabolic or functional level.
PET CT scan is advised by the doctor in case of suspicion of any form of cancer, look for treatment response, evaluate metastasis to various body systems and assist with tailoring the best treatment course. Ultrasound on the other hand is a simpler, cost effective and fast procedure which is used to evaluate for abnormality using sound waves.
The ultrasound machine is equipped with a transducer that uses sound waves to visualize and assess for abnormality in the body. Ultrasound is commonly used for pregnancy monitoring and assessment of basic functional abnormalities like kidney stones, liver disease assessment, gallstones, etc. Ultrasound would be the preferred testing modality since there is no exposure to any type of radiation.
What is PET CT?
(PET CT – positron emission tomography) is a very advanced diagnostic procedure that integrates a PET scan and CT scan to evaluate for abnormality in the body. PET CT utilizes a radioactive tracer, typically FDG, to evaluate for abnormality.
Common Uses of PET CT:
- Detecting and staging cancers.
- Monitoring response to cancer treatment.
- Identifying recurrence or spread of tumors.
- PET CT is helpful in heart diseases
- It helps to check blood flow within the heart and functions.
- PET CT is effective in detecting neurological abnormalities like epilepsy, Alzheimer’s disease etc.
What is Ultrasound?
Ultrasound uses sound waves of high frequency for the detection of abnormalities in the body. Ultrasound is commonly referred to as sonography which provides real time images of the body organs. Sound waves produced by the transducer bounce back and help to make the real time images of the organs.
What Are The Uses of Ultrasound?
- Mainly used to monitor pregnancy.
- Used to monitor growth and development of the fetus.
- Assists in detecting kidney stones.
- Assists in detecting gallstones.
- Assists in assessing heart function.
- Helpful in identifying gallstones, liver disorders etc.
- Can identify tumors. Can help guide procedures.
Differences Between PET Scan and Ultrasound
| Features | PET CT scan | Ultrasound |
| Technology Used | Combines radioactive tracer with CT imaging | Sound waves for the real time image generation |
| Type of Information | Both functional and anatomical details | Structural and motion based images |
| Radiation | Yes | No |
| Details of Imaging | Highly detailed images | Real time images with less detail |
| Best suitable for | Cancers, heart and neurological diseases | Pregnancy, abdominal organs and fluid detection |
| Time taken | Around 1 to 2 hours | Around 15 to 30 minutes |
| Cost | Very Expensive | Affordable |
| Portability and Availability | Not portable, less availability | Portable and widely available |
| Safety Concern | Radiation exposure not suitable for pregnant women | No radiation exposure and is safe for pregnant women |
| Real Time Imaging | Provides static images with structural data | Provides real time images with movement |
What Are the Advantages of PET CT?
PET CT imaging integrates functional and anatomical imaging, and thus is extremely effective in determining stages for cancer. PET CT can distinguish between malignant and benign cancer and is very helpful in detecting spread, or metastases, of the cancer in the body. The imaging also provides this useful information for treatment, and, if treatment is ongoing, for assessment of therapy.
In addition to being important for detecting recurrence of cancer, PET CT is very powerful for diagnosing neurological abnormality. PET CT imaging can optimize body imaging by utilizing wider angles to help eliminate unwarranted invasive procedures and provide patients with the right care at the right time.
What Are the Advantages of Ultrasound
Ultrasound imaging does not expose the patient to radiation and is therefore safe for diagnostic testing of quality assessments. It is also relatively inexpensive, quick, and generally more accessible than other diagnostic testing. Ultrasound is easy to transport and is very effective.
The biggest advantage of ultrasound is that it provides real-time moving images, which allows gallstones, for example, to be directly visualized, and it can help guide some surgical interventions as well. Ultrasound is non-invasive and is safe to use repeatedly, especially for longitudinal observations of patients with chronic diseases or conditions. Ultrasound can also be done rather easily in an outpatient/practice setting, and is typically a convenience, both for the patient and the clinician.
Also Read: Difference Between PET CT Scan and MRI Scan
PET CT Limitations
- Expensive in comparison to ultrasound.
- Scans expose the patient to radiation.
- The scan requires specialized scans to have the doctor interpret the images.
- Should not be used in pregnancy.
- Does not detect small tumors or tumors with a low metabolism.
Ultrasound Limitations
- Has less excursion than the PET CT.
- Does not show metabolic information.
- Can be unclear especially in obese patients.
- Dependent upon technician and thus can vary in quality.
- Limited to deeper/more complex structures inside.
Conclusion
PET CT scan is a more advanced and detailed diagnostic procedure when compared to other modalities like ultrasound, CT, and MRI. Ultrasound utilizes sound waves to detect abnormalities in the body and allows the real time imaging for organs in motion. Ultrasound is much more affordable and widely used compared to PET CT.
There are many advantages and disadvantages to both modalities and a physician will recommend a specific procedure after knowing the history and symptoms of the condition. PET CT is used for cancer conditions like stage, metastasis, treatment effectiveness, etc. Ultrasound is often used for pregnancy and well-being of the fetus. Additionally, it is used to identify abnormalities in abdominal organs.
