The Department of Radiology & Radiological Sciences

    Prepare a Patient for an Imaging Study or Radiology Procedure

    Prepare a Patient for an Imaging Study or Procedure in Radiology

    Prepare a Patient for a CT

                            General Instructions

    Little preparation is needed for a CT scan.  Patients are asked to drink plenty of water both before and after the exam, especially if the exam is performed with oral or intravenous contrast.  Patients will be asked to remove jewelry and other metallic objects that might interfere with the scan. 

    Patient Screening Prior to Administration of Iodinated Contrast

    Prior to the administration of iodinated contrast, patients are screened for the following:

    • Previous reactions to iodinated contrast media
    • All severe allergies and reactions (both medications and food)
    • History of diabetes, kidney disease, pheochromocytoma, solitary kidney, kidney or other transplant, or myeloma
    • Current use of any metformin-containing medications
    • For women of child-bearing age, currently or possibly pregnant or currently breast-feeding.

    Premedication Instructions for Patients with Contrast Allergies

    • Prednisone 50mg po at 13 hours, 7 hours and 1 hour prior to planned administration of intravenous contrast plus diphenhydramine 50mg po, iv or im at 1 hour prior to planned administration of intravenous contrast


    • Methylprednisolone 32mg po at 12 hours and 2 hours prior to planned administration of contrast plus diphenhydramine 50 mg po, iv or im at 1 hour prior to the planned administration of contrast


    • Hydrocortisone 200mg iv at 13 hours, 7 hours and 1 hour prior to planned administration of intravenous contrast if patient is unable to take po medications

                Creatinine Testing Prior to Contrast Administration

    Routine creatinine testing prior to contrast administration is not necessary in all patients.  The major indications are age over 60, history of renal insufficiency, diabetes mellitus, or hypertension. 

    Contrast Administration in Patients with Elevated Creatinine

    Estimated glomerular filtration rate is a better predicator of renal dysfunction than creatinine alone.  The decision to proceed with contrast administration in patients with an estimated GFR < 45 ml/min/1.732 is a matter of clinical judgment, based on the individual circumstances of the patient and following consultation between the radiologist and requesting physician.   Strategies to prevent nephropathy in patients with renal impairment include hydration, reduction of contrast dose, and discontinuation of nephrotoxic drugs. A critical diagnostic study should not be delayed because of excessive concern regarding possible contrast nephropathy.

    Contrast Administration in Patients with Renal Failure

    Patients on dialysis can receive IV contrast, and early post-procedural dialysis is not routinely required; however, the fact that a patient is on dialysis should not be regarded as automatically allowing the administration IV contrast.  The administration of contrast may jeopardize the return of renal function in patients who are receiving dialysis for acute renal failure and may further worsen renal function in patients who still make some urine but receive dialysis intermittently.  The volume of iv contrast should also be considered in patients on dialysis who are at risk for volume overload.

    Contrast Administration in Patients Receiving Metformin

    Metformin should be discontinued at the time of the procedure, withheld for 48 hours subsequent to the procedure, and reinstituted only after renal function has been re-evaluated and found to be normal.

    Contrast Administration in Pregnant Patients

    The iodine content of contrast media has the potential to cause hypothyroidism in the neonate. Pregnant women who receive an intravenous iodinated contrast agent are counseled that neonatal thyroid function should be checked in the first week of life.  Informed consent is obtained prior to the administration of contrast in pregnant patients.

    Vascular Access and Use of Central Lines and Ports

    IV Access for CT Studies

    The type and location of intravenous access is determined by the examination to be performed. 

    • A single phase exam may be performed with hand injection via a 22G iv. 
    • Multiphase exams and CT angiography can only be performed with power injection, and a 20G iv or larger is required.
    • Right arm injection is preferred unless the exam is to evaluate the right upper arm arterial anatomy, in which case the left arm is used.
    • Both arms must be injected to evaluate central venous patency.
    • Power injection is not permitted through an iv in the volar aspect of the wrist, the foot or the external jugular vein.
    • Power injection also is not permitted through an iv that is not functioning well, i.e. has poor blood return or is difficult or painful to flush.

    Central Lines and Ports for CT Studies

    Catheters that may be used for power injection include the following:

    • Power PICC
    • Power port
    • Cook Turbo Flow central venous catheter
    • Cannon II, Cannon II Plus, Trifusion Pheresis or other dialysis catheters.  Dialysis catheters may only be used if approved by an IR or nephrology attending with a written order.
    • Tunneled “Hickman”-type catheters and ports than cannot be confirmed to be “power” ports cannot be used for power injection.

    Prepare a Patient for an MRI

                            General Instructions

    Patients are prepared for an MRI by removing all unnecessary metallic objects, including jewelry and drug delivery patches.

    All patients and other individuals in the room during the actual scan receive acoustic noise protection. When possible, two forms of noise protection are utilized, i.e. ear plugs and pads or head phones.

                            Patient Screening Prior to MRI

    Patients are thoroughly screened for any absolute contraindications to an MRI which are:    

    • Intracranial aneurysm clips
    • Ocular metallic foreign bodies
      • If the patient or guardian is not sure of the presence of an ocular object, but there is a significant likelihood based upon the individual's past experience or occupation, MRI is not performed until independent verification is made.
      • To independently verify the presence or absence of an ocular object, the patient should be referred for an x-ray procedure. A single Water's view is normally sufficient; however, a supplementary CT exam of the orbits using 3mm contiguous slices may also be required at the discretion of the attending radiologist following review of the plain film.
    • Cardiac pacemakers
    • Any electrically active implant

    Patients are also screened for other potential contraindications to an MRI which include:

    • Cochlear implants
    • Any known ferromagnetic metallic materials within the body
    • Pregnancy
    • Coils, stents, and filters 
      • Patients with a history of coil, filter or stent implantation are not granted access to the MRI scan room until the device is identified and the manufacture’s MRI labeling information is reviewed and approved. 
      • Patient is scanned according to the manufacturer guidelines in regards to surface coil selection, dB/dt, T/m, G/cm monitoring of Specific Absorption Rate (SAR) and magnet strength, and configuration.

    Creatinine Testing Prior to Gadolinium Administration

    Routine creatinine testing prior to contrast administration is not necessary in all patients.  Serum creatinine with calculation of eGFR should be performed in patients with any of the following risk factors:

    • Age over 60
    • History of kidney disease, including tumor and transplant
    • Family history or kidney failure or disease
    • Diabetes treated with insulin or other prescribed medications
    • Hypertension requiring medication
    • Multiple myeloma
    • Solid organ transplant
    • History of severe liver disease

    Gadolinium in Patients with Impaired Renal Function

    Nephrogenic systemic fibrosis (NSF), a serious, debilitating, and sometimes fatal scleroderma-like disorder, is associated with the administration of intravenous gadolinium. The primary risk factor is renal failure (patient on dialysis or with a GFR < 30).   The guidelines for administration of gadolinium are as follows:

    • Gadolinium should be avoided or minimized in patients with known renal failure (eGFR<30ml/min) or renal insufficiency (eGFR<90ml/min). If enhanced MR is deemed necessary by the radiologist, the exam will be performed after informed consent, with single-dose Multihance or other alternative to Omniscan (gadodiamide). Omniscan (gadodiamide) should be avoided in patients with any amount of renal insufficiency.
    • Single-dose Multihance or other gadolinium contrast agent will be used in place of Omniscan (gadodiamide) for enhanced MR studies in patients with any known renal insufficiency (eGFR<90 ml/min).
    • Patients with an eGFR>90ml/min reported within 30 days, and who have not had intervening chemotherapy or other treatment or condition that might deteriorate renal function, may receive any gadolinium agent.
    • Patients with known renal insufficiency should not receive additional doses of gadolinium contrast within a 48 hour period. If additional gadolinium contrast is required for a patient with known renal insufficiency within 48 hours of the initial dose, Radiologist approval is required.
    • Informed consent, obtained by a physician, will be required for gadolinium injection in dialysis patient and all patients with known renal insufficiency with an eGFR<30 ml/min, and for all dialysis patients. A written order for the gadolinium contrast is required from the radiologist. This order must arise explicitly from the radiologist and NOT from either a referring physician or an MR imaging protocol standing order. The name of the patient, the name and specific brand of gadolinium contrast, dose, route, and rate of administration should all be explicitly specified on the order, along with the date and signature of the requesting radiologist.
    • Verbal and written instructions will be given to renal insufficiency patients after receiving intravenous gadolinium. Patients with renal insufficiency who receive gadolinium-containing contrast agents should be aware of the following possible signs and symptoms of NSF/NFD, as directed by the FDA warning, and advised to seek medical attention if these occur: swelling and tightening of the skin; difficulty extending the joints of arms, hands, legs, and feet; weakness, reddened or darkened areas on the skin; burning or itching of the skin; and deep bone pain in the hips and ribs.
    • Hemodialysis patients who receive intravenous gadolinium contrast will receive dialysis treatments immediately after the procedure (initiated within 2 hours) and the day following the enhanced MR exam.
    • For administration to patients on chronic ambulatory peritoneal dialysis (CAPD) or continuous cycler-assisted peritoneal dialysis (CCPD) (also known as automated peritoneal dialysis, or APD), there appears to be strong reason to hesitate to administer these agents. As noted above, this process of dialysis seems to be relatively ineffective at clearing the gadolinium from the body. Thus, special caution should be exercised when deciding whether a peritoneal dialysis patient should receive gadolinium-based MR contrast agents. If it is decided that they should be administered such agents, administration of the lowest reasonable dose is strongly recommended. In the past, it had been recommended that the patient avoid periods of a dry abdomen (i.e., no dialysate in the peritoneal cavity) and that the patient be advised to begin additional dialysis self-treatments or CCPD treatments immediately upon the termination of the MR examination in which the GBMCA was administered. These suggestions seemed prudent, although the efficacy of these recommendations had not been established. However, in light of the near-total apparent ineffectiveness of peritoneal dialysis at clearing the gadolinium from the body, it may well be worth considering immediate initiation of hemodialysis in peritoneal dialysis patients who receive even a low dose of a GBMCA (gadolinium based MR contrast agent), or not administering the agent if clinically feasible.
    • Withholding clinically indicated gadolinium contrast can also be associated with its own risks, which should be considered in the decision-making process for all patients with kidney disease.

    MRI in Pregnant Patients

    MRI procedures in pregnant patients are performed only in those cases where the only alternative procedures utilize ionizing radiation, and the procedure cannot be reasonably postponed until after the pregnancy. If it is decided that the procedure is to be performed, the radiologist must explain the benefits/risk of the procedure to the patient and obtain written consent.

    Gadolinium in Pregnant Patients

    Intravenous gadolinium is contraindicated in pregnancy and should only be used if absolutely essential and only after discussion of the potential risks and benefits with the patient and referring clinician.  Informed consent is obtained prior to the administration of gadolinium in pregnant patients.

    Prepare a Patient for a PET Scan

    The patient should be NPO (except water) for 4-6 hours prior to their appointment time.

    The patient should arrive 30 minutes before appointment time to check in and complete paperwork.  The patient will be escorted to a prep room where they will be injected with FDG for the scan.  There are no side effects from the injection of radiolabeled glucose.  They will rest quietly in the prep room for approximately 1 hour depending on the type of scan being performed.  Subsequently, they will be brought into the scan room to have their scan performed, which will take approximately 30 minutes. 

    Patients with type 1 diabetes need to be euglycemic without recent injection of insulin. The study should be scheduled for late morning, with the patient eating a normal breakfast at around 7am and taking the normal amount of insulin.  The patient should then fast for at least 4 hours before the exam.

    Patients with type 2 diabetes should fast for at least 4 hours and continue oral hypoglycemic as usual.

    If claustrophobic, the patient should bring a driver with them to the appointment.  They should inform the technologist upon arrival in the department that they are claustrophobic.  They may be offered Valium, if they have a driver and it is not contraindicated.  Alternatively, they can get an order from their doctor and take an anti anxiety medication immediately prior to arrival in the department.

    Strenuous activity is to be avoided 12-24 hours prior to the exam.  This includes physical therapy.

    Smoking and nicotine should be avoided immediately prior to the scan.

    Copies of outside scans, if available, should be brought to the department.

    All jewelry and metal should be removed prior to entering the scan room.

    In patients with thyroid cancer who have rising thyroglobulin and negative I 131 scan, FDG PET can be used to evaluate for papillary and follicular thyroid cancer.  These patients should be pretreated with thyrogen prior to their PET scan.  This can be scheduled in the nuclear medicine department or through the patient’s physician.

                Prepare a Patient for an Ultrasound

    Most ultrasound examinations do not require any preparation; however, patients undergoing an abdominal, gall bladder or renal artery ultrasound should fast for at least six hours prior to the exam.

    Prepare a Patient for an X-ray or Fluoroscopic Exam

    No preparation is needed for a routine X-ray.  Most GI studies such as esophagrams, UGI, and barium enemas require that patients fast for 8 hours prior to the exam.  Exams such as feeding tube checks to verify placement, nephrostograms, and cystograms do not require patients to be fasting.  Enemas and IVP patients are required to do a colon cleansing prep prior to the exam.

                Prepare a Patient for a Procedure

    A nurse in the department of radiology calls each patient scheduled for a procedure at least five days prior to the appointment unless the appointment is made less than five days prior to the scheduled date and time.  During this call, the nurse reviews the patient’s medical history and medication list and gives the patient instructions based on the type of procedure that is planned.  A letter containing these instructions and directions to the radiology department is sent to the patient following this call.

                                        General Instructions/Information

    Patients who are undergoing outpatient procedures should arrive one hour before their scheduled appointment time and check in at the radiology front desk (room 1145) in the main Vanderbilt University Hospital. 

    Patients who are undergoing a procedure that requires overnight observation should arrive 1.5 hours before their scheduled appointment time and should stop by the admitting office prior to checking in at the radiology front desk.

    Patients should leave all valuables at home.

    Patients who will receive sedation or anesthesia during their procedure should be accompanied by a responsible adult who will be able to drive the patient home.

    Most procedures that involve sedation last 1 to 2 hours with a 2 to 4 hour recovery period following the procedure.

                                        NPO (Fasting) Instructions

    Only patients who will receive sedation or anesthesia during the procedure need to be NPO.

    • No solid food or milk products for 6 hours prior to the procedure.
    • No clear liquids for 2 hours prior to the procedure.
    • Take all regular medications as scheduled with small sips of water unless otherwise directed.

    Instructions for Holding Medications Prior to Procedures

    Medication                                                               Instruction

    ASA 325mg                                                                Hold 5 days

    ASA 81mg                                                                  Do not hold

    Plavix                                                                          Hold 5 days

    Coumadin                                                                   Hold for INR </= 1.5

    Lovenox therapeutic dose (1mg/kg)                               Hold 24 hours

    Lovenox prophylactic dose (30 – 40 mg)                       Hold 12 hours

    Fundaperinux (Arixtra)                                                 Hold 24 hours

    SQ Heparin                                                                 Hold AM dose

    Aggrenox                                                                    Hold 7 days

    Dabigatron (Pradaxa)                                                   Hold for 2 days if CrCl>50

                                                                                      3 – 5 days if CrCl<50

    Fragmin                                                                      Hold dose the day of procedure

    NSAIDs                                                                       Hold 48 hours before liver, lung or kidney biopsies

    Insulin – if pt NPO                                                     Hold all po and long-acting insulin  Take ½ short-acting insulin dose the morning of the procedure

    Metformin                                                                  Hold for 48 hours after procedure and confirm normal renal function prior to restarting 

                            Informed Consent

    The department of radiology recognizes the right of all patients to make informed decisions regarding health care.  Informed consent is obtained prior to all interventional or invasive procedures in accordance with the policy approved by Vanderbilt University Medical Center. 

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