X-Ray Tests for Adrenal Gland Tumors
There are 4 primary x-ray tests to examine the adrenal glands (and the rest of the abdomen) for the presence of a tumor (the word "tumor" simply means "mass". Tumors can be benign or malignant). Some of these tests are better than others and are therefore used routinely, while one or two are used infrequently yet can yield important information when positive.
This is the fastest, cheapest, and most readily available test to look at the kidneys and adrenals. But, it is the least accurate, so it is usually not used as much as the CT scan. Can be used to examine any type of adrenal tumor.
The CT scan (also called CAT scan) is very accurate at examining the adrenal glands and other abdominal structures and can be used on any type of adrenal tumor. Like the other 3 tests in this group, the CT scan is painless. It will take about 30 minutes to complete. The pictures which result are very good at finding tumors throughout the body, and very accurate measurements can be taken which help the planning of subsequent therapies. This scan shows a left adrenal gland (yellow) lying on top of the left kidney (red) and behind the pancreas (green). The spleen is outlined in blue. This is the normal location for an adrenal, its just a lot bigger than it should be. The right adrenal gland is its normal small size and cannot be seen on this CT scan (as expected). Tumors of this size ( less than 6cm, or 2.5 inches) are rarely cancerous and lend themselves very nicely to laparoscopic adrenalectomy.
This CT scan, on the other hand, shows a much larger adrenal gland. This right adrenal (outlined in yellow) measures18 cm (8 inches) which is much more worrisome for cancer. Also worrisome (although not so apparent with the yellow line on the picture) is that the edges of this tumor are not well defined, suggesting it is malignant and growing into surrounding structures. The liver (normal) is outlined in red, and the left kidney (normal) is outlined in blue. Large tumors and those with ill-defined borders are not suited for laparoscopic adrenalectomy.
The MRI (also called an MR scan or NMR scan) is very similar to the CT scan in the type of information and pictures it provides. The scan takes about an hour and uses magnetic fields to generate pictures of body structures rather than x-rays like the CT scan or sound waves like the ultrasound. Often pheochromocytomas enhance (light up brightly) on an MRI scan which is so characteristic that it is almost as accurate as a biopsy, yet this test can be used for any type of adrenal tumor. The MRI shown here is different from the other pictures on this page in that the patient is not "cut in half" across their body, but rather they are "cut in half" down the length of their body as if the front half was removed and we can see inside them. This MRI shows a much enlarged left adrenal (outlined in yellow) on top of the left kidney (outlined in red). This tumor was benign as was suggested by its moderate size and nice smooth edges. This scan also shows very nicely the relationship the left adrenal has to the spleen (outlined in pink). The left adrenal normally lives on top of the left kidney and below and behind the spleen. The liver is normal sized and is outlined in blue. The spinal column can be seen as a series of discs lying on top of one another down the center of the picture.
The MIBG scan is used only to detect the presence and location of adrenal pheochromocytomas. This test does NOT detect any other type of adrenal tumor. MIBG is another nuclear medicine scan which takes advantage of the fact that endocrine cells make hormones. Just like the sestamibi scan which makes hyperactive parathyroids radioactive so they can be seen on special x-ray film, the MIBG scan shows pheos. A special radioactive dye is given to a patient which is a precursor for adrenaline (the hormone made by the adrenal medulla). This dye is concentrated in the hyperactive endocrine tissue which comprises the pheo and it can be seen on x-ray film. The picture on the right shows a bright pheo in the patient's left adrenal gland. To make the picture easier to interpret, the radiologist gave the patient a second radioactive dye which is absorbed by the kidney. The computer interprets the dye in both kidneys as black areas, which accounts for the two "empty" areas on the scan. The pheo, therefore is the bright spot (the adrenal) on the top side of the left (empty) kidney. This test takes about an hour a day for 3 or 4 days. Note: X-rays are typically read as if we were looking at the patient, therefore, the patients left side will be on the right side of the picture we are viewing.