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CT Scans and Contrast: When do I order a test with some type of contrast? Many Computed Tomography (CT or CAT scans) require the patient to have a contrast agent before or at some point during the scan. There are two kinds: IV contrast (Iodine), and Oral Contrast (aka Readi‐Cat). When writing an order for a CT scan, please use the following guidelines. If you have any questions, please contact our helpful schedulers at (907) 212‐3146; our technologists at (907) 212‐2862; or alternatively one of our radiologists at (907) 212‐3148. IV CONTRAST GUIDELINES ORAL CONTRAST GUIDELINES Here are some general guidelines that indicate whether a CT requires IV contrast. IV contrast is required when the radiologist needs to visualize vascular areas. IV contrast required for the following exams: • All angiography • Chest (malignant lesions, etc.) • All abdominal work that emphasizes liver, pancreas, kidney and/or bladder No IV contrast is required for the following CT exams: • Renal Stone Study • Spine workups including C, T and L‐spine • Extremity work (i.e. ankles, knees, wrists, etc.) • Patients who are in renal failure* (and are not on dialysis) • Chest High Resolution (i.e. interstitial lung disease, pulmonary fibrosis, bronchiectasis‐‐typically ordered by pulmonologist) • General brain screening • General sinus, orbit or maxillofacial imaging * patients where renal function is in question need a referral for BUN/
creatinine, within last 30 days, please!
These are the guidelines for order a CT with oral contrast like Readi‐cat*. Oral contrast is required when the radiologist needs to visualize the GI tract. An Abdomen CT scan will visualize from the bottom of the lungs through the top of the pelvis bone. It will not include the pelvic area or the bladder – to include these areas, order the abdomen/pelvis CT scan mentioned below. Patients will be given oral and IV contrast (iodine) unless specified by a urologist. Prep for Abdomen CT Scan • Do not eat or drink anything four (4) hours prior to the examination. Thirty (30) minutes before exam, drink one (1) bottle of oral CT contrast. An Abdomen/Pelvis CT scan will visualize from the bottom of the lungs through the bottom of pelvic anatomy (prostate, rectum). It is generally done on patients whose symptoms are not specific to kidney, ureter or bladder. Patients will be given oral and IV contrast. Use the following oral dosing schedule for this exam, depending on appointment time. Prep for Abdomen/Pelvis CT Scan prior to 9 a.m. • At 9 p.m. the evening before the exam, drink one (1) bottle of oral CT contrast. You may eat and drink as desired after taking the oral contrast until midnight. • On the morning of the exam, do not eat or drink anything other than the oral CT contrast. Thirty (30) minutes before the exam, drink the second bottle of oral CT contrast. Prep for Abdomen/Pelvis CT Scan after 9 a.m. • Drink one (1) bottle of oral CT contrast three (3) hours prior to the exam time. • Nothing to eat after the first bottle of oral CT contrast. Thirty (30) minutes before the exam, drink the second bottle of oral CT contrast. *Readi‐cat is available at our Front Desk. For a small supply in your office, contact Nathan Switzer at 212‐6032. What do I do when a patient has had a prior contrast reaction to iodine? Patients with a history of prior serious allergic‐type reactions to intravenous contrast ad‐
ministration should not have subsequent iodinated contrast injection if another imaging procedure is available that will yield the desired clinical information. If a procedure involv‐
ing intravenous iodinated contrast must be performed, nonionic contrast should be used and premedication should be employed. There are two accepted regimens for prophylactic premedication for iodinated contrast injection. The published literature suggests equivalent efficacy for these protocols. • 32 milligrams of methylprednisolone given orally 12 hours and 2 hours prior to the administration of intravenous iodinated contrast material • 50 milligrams of prednisone given orally 13, 7 and 1 hour prior to the administration of intravenous iodinated contrast material. 50 milligrams of diphenhydramine given orally 1 hour prior to the exam Updated 3/2008 for Dr. Tonya Caylor at the Providence Family Medicine Center