Why three phases
Different formations accumulate contrast in different ways over time: hepatocellular cancer accumulates brightly in the arterial phase and is “washed out” in the delayed phase, hemangioma is filled gradually, metastases are visible in the venous phase, pancreatic tumors appear as hypodense areas in the pancreatic phase; renal tumors are characterized by the nephrographic phase. Such a study allows making a diagnosis without a biopsy in many cases, assessing operability (vascular involvement), planning resection of the liver or pancreas, and assessing the response to chemotherapy. Preparation: creatinine, 6 hours fasting, no allergy to iodine.
Indications
- aneurysm and aortic dissection, chest and back pain with suspected vascular accident;
- coronary heart disease - non-invasive assessment of coronary arteries, calcium index;
- pulmonary embolism (PE) with shortness of breath and chest pain;
- stenosis of the carotid and cerebral arteries, cerebral aneurysms, stroke;
- obliterating atherosclerosis and intermittent claudication - arteries of the legs before surgery;
- planning of stenting, bypass surgery, aortic endoprosthetics, monitoring after them.
What is MSCT
Multislice computed tomography is a layer-by-layer X-ray study in which detectors receive dozens of sections up to 0.5–1 mm thick in one revolution of the tube, and a computer builds a three-dimensional image of the organ. MSCT is performed in 5-15 minutes, accurately shows bones, lungs, stones, hemorrhages, tumors and vessels (with contrast), and is often the method of choice for trauma and acute conditions when MRI is too long or contraindicated.
Preparation and contrast
Non-contrast MSCT does not require preparation. Before a study with intravenous contrast, a test for creatinine (kidney function) and the absence of an allergy to iodine are required; 4–6 hours without eating; When taking metformin, agree on a break with your doctor. Contrast (Unigexol) is administered using an automatic injector; a feeling of warmth for 1–2 minutes is normal. To examine the abdominal and pelvic organs, oral contrast is used, which is drunk 30–60 minutes before the scan. Remove metal objects from the examination area. The radiologist’s conclusion is completed within 1–2 hours, the images are issued on film and disk.
Radiation exposure and safety
Modern devices use low-dose protocols; the dose for one study is comparable to several months of natural background and does not accumulate dangerously when prescribed appropriately. MSCT is not performed on pregnant women (except for vital indications); for children - according to strict indications with a minimum dose. Iodine contrast is contraindicated in severe renal failure, iodine allergy and uncontrolled hyperthyroidism. Pacemaker and metal implants are not a contraindication, unlike MRI.
