Nuclear Medicine/PET-CT Specialists

Medical Imaging Center of Southern California

Radiology and Medical Imaging located in Santa Monica & Beverly Hills

Nuclear Medicine/PET-CT Q & A

What is nuclear medicine?

Nuclear medicine, which is also known as molecular imaging, allows our team of physician specialists to diagnose many diseases.

Nuclear medicine is a well-established diagnostic imaging technique that requires the injection of a specific isotope that uses a small amount of radiation to detect specific diseases.

Photo of a full body MRI scan

What studies in nuclear medicine are available? (not including PET-CT)

The following is a list of studies where nuclear medicine can be used.

Bone studies

  • Bone scan (Tc MDP)

Neurological studies

  • Brain Spect Technetium-99m(99mTc) Neurolite [Bicisate]
  • CSF leak study (In-111 DTPA) – looks for CSF leaks
  • SPECT CT fusion scan — degenerative spine disorders

Cardiac studies

  • Myyocardial perfusion Technetium-99m(99mTc) Cardiolite/201 TI Thallium
  • MUGA scan (Tc-labeled RBCs)
Photo of a MRI scan

Oncologic/Infectious Disease studies

  • Lymphoscintigraphy (Tc-Filtered Sulfur Colloid) — lymphedema and tumor in lymph nodes
  • Indium White Blood Cell Scan (In-111 WBC) — infection
  • Sentinel node localization (Tc-Filtered Colloid) — breast cancer or melanoma
  • Gallium scan (Ga67) — neoplasm (for example, lymphoma)

Cardiac studies

  • Myocardial perfusion (99mTc Cardiolite/201 TI Thallium)
  • MUGA scan (Tc-labeled RBCs)

Endocrine and GI studies

Photo of a MRI scan

How do nuclear medicine studies work?

Lymphoscintigraphy (Tc Sulfur Colloid)

Lymphoscintigraphy allows the radiologist to see the workings of your lymphatic system and it can help in diagnosing lymphedema, a condition in which lymphatic fluid accumulates in your soft tissues and can lead to inflammation and obstruction. For this scan, radioactive Tc Sulfur Colloid is injected into the web space between your fingers or toes and images are acquired 20 minutes and two hours after the injection.

RBC liver/hemangioma study (Tc-labeled RBC’s)

This scan is helpful in determining whether or not a mass found in the liver is a hemangioma (benign growth) or not. Images of the liver are obtained using red blood cells labeled with a radiotracer. Labeling the blood takes 20-30 minutes, the initial imaging takes 30 minutes, and after a 45-minute break, the SPECT images of the liver are taken. There’s no patient preparation for this scan.

Photo of Dr. Bradley pointing at a MRI scan

HIDA Hepatobiliary scan (Tc Choletec/Tc Disida)

Hepatobiliary scans demonstrate gallbladder function. You’re injected with 99m Tc Choletec. Once on the table, periodic images are taken over the course of one hour. Additional images may be needed after the first set of images is taken, and can take up to four hours.

You must not eat anything six hours before your scheduled appointment or take pain medication on the day of the study — opiate medications such as morphine, Demerol, and codeine may result in a false positive.

Parathyroid scan (Tc-Cardiolite)

Parathyroid scans are helpful in detecting parathyroid adenoma, as well as glands not seen via ultrasound. Upon arrival, an IV is started and you’re injected with 99mTc Cardiolite. After about 10-15 minutes, images are taken for about 30 minutes. Two hours after initial images are taken, the same images are repeated as well as a SPECT scan of the neck (approximately one hour). There is no preparation for this scan.

Thyroid uptake scan (I-NaI Sodium Iodide Capsule)

Thyroid scans are helpful in evaluating hyperthyroidism, thyroiditis, and thyroid nodules. The thyroid uptake scan requires three visits to the Medical Imaging Center of Southern California. On the first visit, you swallow a small radioactive iodine capsule. Six hours later, you return to have images taken of your thyroid and measurements of the radioiodine uptake are completed. On the second day, you return for another measurement of the radioiodine uptake.

In preparation for this scan, iodine-containing drugs must not be taken for two weeks prior to the scheduled appointment. This includes radiographic contrast and thyroid hormone replacements. For five days prior, no shellfish or iodine-rich foods should be eaten. Additionally, you should not eat or drink for four hours prior to coming in on the first day.

Brain SPECT (Tc Neurolite)

Brain SPECT scans visualize how blood flows to different areas of your brain. This scan is commonly ordered for patients with memory loss due to trauma or to detect early Alzheimer’s disease. For this scan, an IV is placed and you’re injected with Tc Neurolite (Bicisate). Images are taken 20 minutes post-injection for about 40 minutes. There is no preparation for this scan.

Myocardial perfusion scan (Adenosine)

A myocardial perfusion scan is a two-part study to assess blood flow and the function of your heart. There are two types of stress tests offered at Medical Imaging Center:

Treadmill stress

You’re monitored while on a treadmill, which increases in speed and inclines until your heart rate reaches a certain level. The technologist then injects the tracer and you exercise for an additional two minutes.

Adenosine stress

Your heart is stressed pharmacologically using Adenosine while you’re lying down for about five minutes. The radioactive tracer is injected at two minutes. Images of the heart muscles are obtained for about 120 minutes.

For both tests, images are taken upon your arrival and after you complete the stress test.

You must be caffeine free for 24 hours prior to the test, which includes coffee, tea, colas, chocolate, and decaf products. You also shouldn’t eat or drink anything for four hours prior to your test, except water. Diabetic patients may have a light meal if needed.

Bone scan (Tc MDP)

Bone scans can be helpful in identifying fractures, tumors, arthritis, and infection (osteomyelitis). For this scan, you’re injected with a small amount of radioactive tracer (Tc MDP) intravenously. This tracer travels throughout your body to your skeletal system and is distributed into your bones.

After the injection, you may leave the facility for a 2-3 hour break so that the tracer can be absorbed. During this time, you’re asked to drink plenty of water and empty your bladder.

Upon return, images are taken either of the entire body or a specific area, depending on what the referring doctor is requesting. There’s no preparation for this scan but it may be helpful to drink plenty of water prior to your scheduled appointment.

MUGA scan (Tc-labeled RBC’s)

The multiple gated acquisition scan (MUGA) is a noninvasive way to measure the function of your heart while it’s moving. The scan provides a good look at the ventricles of your heart and monitors the ejection fraction. It can also be helpful in following the strength of cardiac function, cardiomyopathy, post-infarct or post-chemotherapy treatment. There’s no preparation for this scan.

Indium White Blood Cell scan (Indium 111 Oxine)

The indium white blood cell scan is helpful in detecting areas of infection or inflammation by tagging your white blood cells with a small amount of radioactive material. Once your white blood cells are tagged, they are injected into your vein and areas of infection or inflammation. This can take up to three hours and delayed images (24 hours later) may be necessary. There’s no preparation for this scan.

What is a PET-CT?

PET-CT (Positron emission tomography) with FDG (Fluro-deoxyglucose) combines nuclear medicine with a CT scanner and can detect the earliest signs of cancer and neurodegenerative brain disease as well as other disease processes.

One of the most common PET-CT techniques requires the intravenous injection of a glucose analog (FDG) attached to an isotope that allows our doctors to visualize and measure abnormal molecular cell activity, which highlights and detects cancer, brain disorders, and heart disease.

A number of new PET-CT isotopes are now available, including Amyvid™ (PET-F18) for Alzheimer’s disease and PSMA (PET-68- Gallium) for prostate cancer. Netspot (Gallium- 68 dotatate) is used to diagnose pancreatic and neuroendocrine tumors.

How do I prepare for a PET/CT scan?

Here are a few things you can do to prepare for your PET/CT scan. This is not necessarily a comprehensive list.

  • Drink lots of water before your exam
  • Wear comfortable clothing without any metallic objects such as buttons and zippers
  • You should not eat after midnight prior to your exam
  • Your sugar intake should be low for 24 hours prior to your exam
  • If you are diabetic, please contact Medical Imaging Center of Southern California for special instructions

How a PET/CT scan works?

  • You will sit in a quiet room for approximately 45 minutes while the technologist injects a glucose analog (FDG) attached to an isotope
  • You will then be guided to lie on a flat table/bed that moves slowly through the PET scanner
  • The scanner has cameras that detect the gamma rays that are emitted and then turns them into electrical signals, which a computer processes to generate the medical images
  • The computer assembles the digital images that are produced into 3D images of your body


To learn more, call Medical Imaging Center of Southern California.