CEA-Scan

The CEA-Scan is a diagnostic imaging procedure used primarily to detect tumors that express carcinoembryonic antigen (CEA), a protein often found in high levels in various types of cancer, most notably colorectal cancer. The test involves the use of a radiolabeled antibody, specifically Technetium (99mTc) arcitumomab, which targets CEA molecules.

Overview

CEA-Scan is utilized in the evaluation of patients with known or suspected cancer, helping to determine the extent of the disease and to monitor the effectiveness of therapy. The procedure is particularly useful in the staging and restaging of colorectal cancer, providing valuable information that can influence treatment decisions.

Procedure

During a CEA-Scan, the patient is injected with Technetium (99mTc) arcitumomab, a radioactive antibody that binds specifically to CEA-expressing tumor cells. After allowing time for the antibody to circulate and bind to potential tumor sites, images are taken using a gamma camera. These images help in identifying areas where the radiolabeled antibody has accumulated, indicating the presence of tumor cells.

Indications

The primary indication for a CEA-Scan is the detection and localization of CEA-expressing tumors in patients with:

• Suspected recurrence of cancer
• Known metastatic disease
• Evaluation of tumor response to treatment

Advantages

The CEA-Scan offers several advantages over other imaging modalities:

• It provides specific targeting of CEA-expressing cells, which can improve the accuracy of tumor detection.
• It can be used to assess the whole body in a single imaging session.
• It is particularly useful in cases where other diagnostic tests have provided inconclusive results.

Limitations

Despite its benefits, the CEA-Scan has limitations:

• It may not detect tumors that do not express CEA.
• There can be false positive results due to non-tumor related causes of increased CEA levels.
• The resolution of the images may not be as high as those obtained with more advanced imaging techniques like PET or MRI.

See also

• Carcinoembryonic antigen
• Colorectal cancer
• Nuclear medicine
• Gamma camera