Prepare a Patient for a CT
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:
Premedication Instructions for Patients with Contrast Allergies
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.
Central Lines and Ports for CT Studies
Catheters that may be used for power injection include the following:
Prepare a Patient for an MRI
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:
Patients are also screened for other potential contraindications to an MRI which include:
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:
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:
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.
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.
Instructions for Holding Medications Prior to Procedures
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
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.