A Computed Tomography Pulmonary Angiogram, commonly known as a CTPA scan, is a specialized medical imaging procedure. It uses CT technology to create detailed images of the blood vessels within the lungs. During the scan, a contrast dye is injected into a vein. This dye travels through the bloodstream, highlighting the pulmonary arteries. This allows medical professionals to assess the condition of these vessels and identify abnormalities.
What a CTPA Scan Diagnoses
The primary application of a CTPA scan is to diagnose a pulmonary embolism (PE). A PE occurs when a blood clot, often originating in the legs as a deep vein thrombosis (DVT), travels to the lungs and blocks one or more pulmonary arteries. This blockage can impede blood flow and oxygen exchange, leading to serious complications. The CTPA scan effectively detects these clots, which appear as darker areas within the bright, contrast-filled arteries.
A CTPA is a valuable imaging choice for diagnosing PE due to its ability to quickly and accurately visualize the pulmonary arterial tree. Beyond PE, a CTPA can also help evaluate other conditions affecting the lung vasculature or heart. For instance, it can assist in ruling out conditions such as aortic dissection, a tear in the body’s main artery, or in assessing pulmonary hypertension, a condition characterized by high blood pressure in the arteries of the lungs and heart.
How the Scan is Performed
A CTPA scan involves several steps to capture clear images. Upon arrival, a healthcare professional will insert an intravenous cannula into a vein in your arm. This cannula administers the contrast dye, which is usually iodine-based. The contrast material is injected quickly to ensure it reaches the pulmonary arteries for imaging.
You will then lie on your back on a movable table that slides into the CT scanner, a large, donut-shaped machine. Your arms will generally be positioned above your head to help maintain a stable position and prevent image distortion. As the scan proceeds, the table will move in and out of the scanner. You will receive specific breathing instructions, such as holding your breath, to minimize motion artifacts that can blur images. During the contrast injection, you might experience a warm flush sensation throughout your body.
Preparing for Your Scan
Preparation for a CTPA scan involves several steps to ensure a safe and effective procedure. You may be advised to fast for a few hours before the scan; confirm specific instructions with your healthcare provider. Discuss all current medications with your doctor, especially if you take diabetes medications or have kidney issues, as some might need temporary adjustment.
Inform the medical staff about any known allergies, particularly to contrast dye or shellfish. Also, inform your healthcare provider if there is any possibility of pregnancy, as radiation exposure needs consideration. Blood tests, such as a creatinine level, are often performed before the scan to assess kidney function and ensure your kidneys can safely process the contrast dye.
Understanding the Results and Potential Risks
After your CTPA scan, a radiologist, a doctor specializing in medical imaging, reviews and interprets the images. The radiologist sends a detailed report to your referring physician, who will discuss the findings with you, typically within a few days. A normal CTPA scan shows pulmonary vessels fully filled with bright contrast, indicating unobstructed blood flow. If a blood clot or other abnormality is present, it appears as a darker area against the bright contrast.
While a CTPA scan is a valuable diagnostic tool, it involves potential risks. Radiation exposure is generally low for a single scan but is cumulative over a lifetime. Healthcare providers weigh the diagnostic benefits against this risk, especially when a pulmonary embolism is suspected, as early diagnosis can be life-saving. Reactions to the contrast dye are another consideration; mild reactions like nausea, itching, or a warm sensation are possible. More severe allergic reactions are rare, and kidney strain from the contrast dye is a possibility, particularly for individuals with pre-existing kidney conditions.