A pheochromocytoma is a rare tumor that typically originates in the adrenal glands, small organs located above your kidneys. These tumors arise from specialized cells called chromaffin cells and can lead to an overproduction of hormones like adrenaline and noradrenaline. While often benign, pheochromocytomas can cause various symptoms due to this excess hormone production, including high blood pressure. Imaging tests, such as a CT scan, are routinely used to help locate and diagnose these tumors.
Why a CT Scan is Used
A Computed Tomography (CT) scan provides detailed cross-sectional images of the body, making it a widely used imaging method for pheochromocytoma. This allows medical professionals to precisely locate the tumor, which most commonly occurs in the adrenal glands, but can also be found in other areas of the abdomen or chest. CT scans can reveal adrenal pheochromocytomas as small as 5-10 mm with a sensitivity greater than 95%.
The scan also helps determine the tumor’s size, consistency, and shape, which can range from 1 to 15 cm, with an average size at diagnosis between 4-6 cm. CT imaging can assess if the tumor has spread to other parts of the body, aiding in treatment planning. Pheochromocytomas often appear as solid or complex masses on CT, and their density is usually higher than 10 Hounsfield units (HU) on unenhanced scans, helping differentiate them from other adrenal lesions.
How to Prepare for the Scan
Preparing for a pheochromocytoma CT scan involves several steps to ensure accurate results and safety. Current guidelines generally do not recommend fasting before routine intravenous contrast material administration for CT scans. However, your doctor may still provide specific instructions regarding food or drink, especially if other procedures are planned.
It is important to discuss all current medications with your healthcare provider, particularly those for blood pressure or diabetes, as adjustments might be necessary before the scan. You should also inform the medical staff about any known allergies, especially to iodine or intravenous contrast dye. If you have a history of contrast allergy, a premedication regimen may be prescribed to reduce the risk of an allergic reaction. This contrast material is administered to enhance image clarity, helping to better visualize the tumor and surrounding structures.
What Happens During the Scan
During the CT scan, you will lie on a movable table that slides into a large, doughnut-shaped machine. It is important to remain as still as possible throughout the procedure, as movement can blur the images. The technologist operates the scanner from an adjacent room but can communicate with you through an intercom system.
If intravenous contrast material is used, it will be administered through a vein, usually in your arm. You might feel a warm sensation or a metallic taste in your mouth as the contrast is injected. The scan itself is typically brief, lasting only a few minutes. You may hear humming or clicking noises from the machine during the imaging process.
Interpreting Your Scan Results
After your CT scan, a radiologist will analyze the pictures to identify any abnormalities. They will look for the tumor’s exact location, its size, and specific characteristics that help distinguish a pheochromocytoma from other types of masses. Pheochromocytomas are often large, exceeding 3 cm, and may appear as round or oval masses with a density similar to that of the liver. Larger tumors can sometimes show areas of necrosis (tissue death), hemorrhage, or fluid-filled regions, making their appearance on the scan inhomogeneous.
The radiologist will then generate a detailed report of their findings, which will be sent to your referring doctor. Your doctor will discuss these results with you, explaining what they mean for your diagnosis and potential next steps, which could include further diagnostic tests or the development of a treatment plan. In most cases, clear CT findings combined with positive biochemical tests provide sufficient evidence for a pheochromocytoma diagnosis.
Risks and Important Considerations
While a CT scan is a valuable tool, it does involve certain considerations. Exposure to ionizing radiation is one aspect. The radiation dose from a single CT scan is low, and medical professionals carefully weigh this risk against the diagnostic benefits, especially for a condition like pheochromocytoma where precise localization is needed.
Another consideration is the potential for reactions to the contrast material. While generally safe, some individuals may experience allergic reactions, ranging from mild symptoms like hives to more severe responses. There is also a small risk of kidney issues, particularly for individuals with pre-existing kidney conditions. Your medical team will assess your individual health profile and take precautions to minimize these potential risks.