PET/CT Scans

Positron Emission Tomography/Computed Tomography or PET/CT scans are non-invasive diagnostic exams that produce images of the body. PET/CT scans involve a special camera that detects energy emitting from the radioactive substance, called a radiotracer.

Benefits of PET/CT Exams

  • PET/CT exams detect diseases sooner than they would normally show up on a CT or MRI scan.

  • PET/CT exams search the entire body for cancer in a single exam and show the extent of disease; they can reveal the primary site or sites and any metastases, allowing the doctor to know which treatment is appropriate.

  • PET/CT exams show whether a tumor is benign or malignant, avoiding the need for surgery.

  • PET/CT exams monitor progress and test recurrence of disease, which might not show up on an MRI or CT scan.

Scheduling Your PET/CT Exam

PET/CT appointments are scheduled M-F from 7:00am to 3:30pm. PET/CT exams are by appointment only and are typically scheduled by your referring physician. If you need to reschedule your PET/CT exam, please call Radiology Scheduling at 314-362-7111 or 877-992-7111, M-F from 7:00am to 5:30pm.

Before Your PET/CT Exam

  • Please confirm with your referring physician's office that any precertification required by your insurance has been completed before your PET/CT appointment.

  • Please arrive at least 15 minutes prior to your appointment to allow for registration time.

  • Please bring a photo ID (driver’s license or state ID), insurance card(s), and a completed Medication Record with you to your appointment.

  • Take your medication as you normally do, unless your referring physician has told you otherwise.

  • You should not chew gum 4-6 hours prior to your appointment.

  • You should arrive to your appointment fully hydrated.

  • For exams before 1:00pm, do not eat or drink anything except water after midnight prior to your exam.

  • For exams after 1:00pm, do not eat or drink anything except water after 7:00am. You may have a light breakfast before 7:00am.

  • Refrain from strenuous physical exercise 24 hours prior to your exam.

  • Wear comfortable, loose-fitting clothing to your exam. In some cases, you will be given a hospital gown to wear during the procedure.

  • Jewelry and other metallic accessories can interfere with the procedure and should be left at home or removed before the exam. You will be given a place to store your items before the procedure.

  • Be prepared to discuss your completed Medication Record, allergies, past medical history, and any previous surgeries.

  • Women should always inform their physician and the PET/CT technologist if there is any possibility that they are pregnant.

  • PET/CT exams involve a special camera that detects energy emitting from the radioactive substance, called a radiotracer. Before the test, patients receive the radiotracer by injection, by swallowing, or inhaling a gas. Although radiotracers are radioactive, the dosage is small.

  • If the radiotracer is injected into your arm, you might feel a cold sensation moving up your arm. If the radiotracer is swallowed, it has little or no taste. If inhaled, you should feel no differently than when breathing normally.

  • It can take anywhere from several seconds to several days for the radiotracer to travel through your body and accumulate in the organ or area being studied. As a result, imaging might be done immediately, a few hours later, or even several days after you‘ve received the radioactive material.

  • With some procedures, a catheter might be placed in your bladder, which might cause temporary discomfort.

During Your PET/CT Exam

  • A technologist will help you onto the screening table and make you comfortable. Once the exam begins, you will be asked to remain still until the exam is over. The technologist will leave and go to another room, but will remain in contact with you through an intercom. You will also be given a call button to talk to the technologist at any time.

  • A PET/CT scanner is a large machine with a round, doughnut shaped hole in the middle, similar to a CT or MRI unit. Within this machine are multiple rings of detectors that record the emission of energy from the radiotracer in your body.

  • A PET/CT scan generally takes 1 to 2 hours, depending on the exam. For a more exact length of time for your specific exam, please call the PET/CT department at 314-362-8275.

Questions About Your PET/CT Scan

Please call the PET/CT department at 314-362-8275 with any questions about your PET/CT scan.


All radiology exams are read by a physician known as a Radiologist. The radiologists at Barnes-Jewish Hospital are all specialized experts in their field. The radiologist will send the results of your exam to your referring physician’s office within 24 hours. If needed, the radiologists are available to discuss your results with your referring physician. Your physician’s office will then in turn discuss the results with you.

About Your Bill

You will receive two bills for your exam:

  • The hospital bill includes the cost to cover equipment, supplies, and technical personnel. For questions, call Hospital Billing at 314-362-0710.

  • The radiologist’s bill covers the professional interpretation of your exam. For questions, call Mallinckrodt Institute (Washington University) Patient Accounts at 314-273-0500.

Patient Forms

To save time please download, print, fill out, and bring to your appointment.

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