Are you having back pain with any of the following?

  • Severe pain, weakness or tingling in your leg(s).
  • Difficulty stopping urination or loss of control of bladder or bowels.
  • Unexplained fever, nausea or vomiting.
  • A history of cancer or unexplained weight loss.

We understand that you are experiencing one or more of the health issues that might be impacting your back pain.

We recommend that you discuss these health issues with your doctor before proceeding with this program.

Once you are cleared by your doctor to do this program, we hope it helps you find relief from your back pain.

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Dr. Pan and Dr. Lee's Blog

What is PET/CT?

Feb 01, 2011

by Ryan Niederkohr, M.D., Nuclear Medicine Physician


Role of PET/CT

PET/CT is a state-of-the-art imaging tool that plays an important role in the treatment of many types of cancer. PET/CT combines two different kinds of imaging into one procedure. The PET portion provides functional or "physiologic" information, while the CT portion provides structural or "anatomic" information. PET/CT scans are often helpful for detecting cancer and determining where or how far cancer has spread. As such, PET/CT scans often help cancer specialists to create optimal treatment plans for individual patients. Later on, PET/CT scans can also help to show how the cancer is responding to that treatment -- and allow for an earlier change of treatment, if needed.

What is Special about PET?

Currently, the most widely used radioactive molecule for PET scan is called fluorodeoxyglucose (FDG), which is essentially tagged glucose. After injection of a small amount of this radioactive sugar, it distributes throughout the body like sugar would. The PET scanner then takes pictures of this distribution throughout the body and the associated CT images use x-rays to create an anatomic map to precisely localize any abnormalities identified on the PET scan. Since most cancer cells take up sugar at a higher rate than normal cells, areas of tumor typically light up brightly on PET scans. If a particular treatment (e.g., chemotherapy, radiation, etc.) later kills the cancer cells or renders them inactive, they will no longer take up the radioactive sugar and no longer appear bright on the PET scan. In many cases, a PET scan can detect cancer cells more sensitively than other imaging studies like CT or MRI. In many cases, a PET scan can also assess response to a particular treatment earlier than CT or MRI can.

Preparation for PET Scanning

A PET/CT scan requires slightly more preparation than a CT or MRI scan. Because the imaging agent is a sugar-based molecule, the patient's glucose level must be in a specific range. Diabetic patients may be directed to alter their medication schedule on the day of the test. All patients must abstain from food and drink (except water) for 6 hours before a PET/CT scan. Patients are also advised to avoid strenuous activity (heavy lifting, etc.) for 2-3 days before a PET/CT scan to prevent imaging artifacts. The imaging agent (FDG) used for a PET scan does not cause any allergic reactions and does not adversely affect the kidneys (unlike CT or MRI scans, where both of these factors are potential concerns).

During the PET Scan

A PET/CT scan takes about 2 hours from start to finish. Upon arrival, a small IV catheter is placed in the arm and the radioactive sugar is injected. This is followed by a 1 hour "uptake period" during which the FDG is allowed to circulate and distribute throughout the body. The patient is then positioned onto the PET/CT scanner, and the actual scan itself takes around 30 minutes. Results are typically available to the referring doctor within 24-48 hours.

Limitations of PET Scan

PET/CT scans provide very important information to cancer specialists, but they are not perfect. Sometimes, areas of infection of inflammation can light up brightly on a PET scan and can potentially be confused with cancer cells. The experience of our interpreting nuclear physicians can often minimize this confusion, but sometimes diagnostic uncertainty persists. A PET scan is not a substitute for tissue sampling and does not replace the need for a traditional biopsy in many situations. Also, a few cancer types do not light up at all on a PET scan -- so, obviously, PET/CT is not useful in those types of cancers. Finally, like most medical imaging studies a PET/CT scan does expose the patient to a small amount of radiation. The risk of this radiation exposure must always be balanced against the need for the scan in terms of how it would affect the patient's cancer treatment strategy.

Kaiser Permanente Santa Clara Nuclear Medicine Department

The Santa Clara Nuclear Medicine Department efficiently performs a high volume of PET/CT scans daily. We were the first Kaiser facility to be awarded a fixed, state-of-the-art PET/CT scanner and we continue to perform the greatest number of PET/CT scans of any Kaiser facility throughout the Northern California region. Our imaging technologists always have patient comfort and convenience as their first priority and our dedicated, specialty-trained nuclear medicine physicians offer extensive experience and skill in PET/CT scan interpretation. We also take pride in working directly with clinical oncology specialists (in association with the Comprehensive Cancer Care center at Santa Clara), optimizing the integration of diagnosis and treatment. We look forward to serving you.

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