Single-Photon Emission Computed Tomography (SPECT)

Single-Photon Emission Computed Tomography (SPECT) is a nuclear medicine imaging technique that uses gamma rays to produce detailed, three-dimensional images of the body's internal structures.

Principle

SPECT works by injecting a small amount of radioactive tracer into the bloodstream. The tracer accumulates in specific areas of the body, such as organs or tissues, and emits gamma rays. A gamma camera, which is a specialized detector, rotates around the body to capture the gamma rays emitted by the tracer.

Procedure

The SPECT procedure typically involves the following steps:

• A small amount of radioactive tracer is injected into a vein in the arm.
• The patient is then placed on a table that slides into the SPECT scanner.
• The gamma camera rotates around the body, capturing images from multiple angles.
• The images are reconstructed using computer algorithms to produce detailed, three-dimensional pictures of the internal structures.

Applications

SPECT is used in a variety of medical applications, including:

• Cardiology: SPECT is used to evaluate coronary artery disease, cardiac function, and myocardial perfusion.
• Oncology: SPECT is used to diagnose and stage cancer, as well as to monitor treatment response.
• Neurology: SPECT is used to evaluate brain function, including blood flow and metabolism.
• Orthopedics: SPECT is used to evaluate bone health and diagnose conditions such as osteoporosis and bone cancer.

Advantages

SPECT has several advantages over other imaging modalities, including:

• High sensitivity: SPECT can detect small amounts of radioactive tracer, making it sensitive to subtle changes in tissue function.
• Good spatial resolution: SPECT can produce detailed images with good spatial resolution, allowing for accurate localization of abnormalities.
• Functional information: SPECT provides functional information about tissue metabolism and blood flow, which can be useful in diagnosing and monitoring disease.

Limitations

SPECT also has several limitations, including:

• Radiation exposure: SPECT involves exposure to small amounts of ionizing radiation, which may be a concern for some patients.
• Limited availability: SPECT scanners are not as widely available as other imaging modalities, such as CT or MRI.
• Long acquisition times: SPECT scans can take several minutes to an hour to complete, which may be uncomfortable for some patients.

Hybrid Imaging

SPECT can be combined with other imaging modalities, such as CT or MRI, to produce hybrid images that combine the functional information of SPECT with the anatomical detail of the other modality. This is known as SPECT/CT or SPECT/MRI.