Skagit Radiology Physician Services

Frequently Asked Questions

1	What are the regimens for patients who require premedication prior to intravenous injection of iodinated contrast?
2	What are the recommendations regarding Metformin usage in patients who receive intravenous iodinated contrast material?
3	What are the indications for cervical spine CT in the setting of trauma?
4	What formulations do you use for intra-articular steroid injections?
5	What are the guidelines regarding barium enemas following incomplete colonoscopies?
6	What are the recommendations for breast-feeding patients who receive intravenous contrast for either CT or MRI examinations?
7	Which procedures require that patients have coagulation studies drawn prior to the procedure?
8	Which medications should be discontinued prior to an invasive radiologic procedure?
9	Is it safe for patients with renal failure to receive gadolinium intravenously for contrast-enhanced MRI examinations?
10	What is the recommended imaging study for evaluation of pulmonary embolus in pregnant patients?
11	What is the imaging protocol for palpable breast masses?
12	What is the policy regarding elevated creatinine levels and intravenous contrast for CT scans?
13	How do you decide if a patient is a suitable candidate for CT angiography examinations? See chart here
14	What coagulation cutoff parameters do you use for invasive radiological prodedures?
15	Which types of intravenous access are suitable for the administration of contrast materials?

What are the regimens for patients who require premedication prior to intravenous injection of iodinated contrast material?

1. Prednisone 50mg PO at 13, 7, and 1 hour before IV contrast. Benadryl 50mg PO/IM at 1 hour before IV contrast.
2. Urgent situation: Hydrocortisone 100mg IV at 4-6 hours and 1 hour before IV contrast. Benadryl 50mg PO/IV/IM 1 hour before IV contrast. Reference: Bush, W.H., et al. Radiology Life Support. New York: Oxford University Press, 1999.

What are the recommendations regarding Metformin usage in patients who receive intravenous iodinated contrast material?

• Discontinue metformin at the time of administering IV contrast. IV contrast may still be given if the patient has taken metformin on the morning of the examination.
• Stop metformin for 48 hours after examination.
• Re-start metformin only after renal laboratory re-evaluation is normal.

Reference: Bush WH, Bettmann MA. Update on metformin (Glucophage®) therapy and the risk of lactic acidosis: change in FDA-approved package insert. ACR Bulletin 1998; 54: 15.

What are the indications for cervical spine CT in the setting of trauma?

The following clinical predictors of injury are appropriate criteria to evaluate patients with CT, rather than radiography.

Injury mechanisms:
• High-speed motor vehicle accident: >35 mph combined
• Motor vehicle accident with death at scene
• Fall of >10 feet

Clinical evaluation:
• Known closed head injury
• Pelvic or multiple extremity fractures
• Neurologic symptoms on physical exam
• Cervical spine radiculopathy on physical exam

Reference: Julian A. Hanson, C. Craig Blackmore, Frederick A. Mann, and Anthony J. Wilson. Cervical Spine Injury: A Clinical Decision Rule to Identify High-Risk Patients for Helical CT Screening. Am. J. Roentgenol., Mar 2000; 174: 713 - 717.

What formulations do you use for intra-articular steroid injections?

Joint	Approach	Technique	Joint volume	Kenalog 40 mg/ml	Marcaine 0.75%
Hip	Anterolateral	Fluoro	4 cc	1 cc	3 cc
Knee	Subpatella	Fluoro	7 cc	2 cc	5 cc
Ankle	Anterior	Fluoro	3 cc	1 cc	2 cc
Post subtalar	Lateral	CT/fluoro	3 cc	1 cc	2 cc
SI joint	Posterior	CT/fluoro	1.5 cc	0.5 cc	1 cc
Shoulder	Anterior	Fluoro	4 cc	1 cc	3 cc
Elbow	Lateral	Fluoro	4 cc	1 cc	3 cc
Wrist	Posterior	Fluoro	1.5 cc	0.5 cc	1 cc
Subdeltoid bursa	Anterior	US	2 cc	1 cc	1 cc
Tendon sheaths		US	1.5 cc	0.5 cc	1 cc

What are the guidelines regarding barium enemas following incomplete colonoscopies?

• For barium enemas ordered following an incomplete colonoscopy, the patient should have the enema scheduled at 7-10 days after colonoscopy if any biopsy, polypectomy, fulguration, or laser coagulation has been performed during the colonoscopy.
• Otherwise, an attempt will be made to perform the barium the same day of the colonoscopy. Of note, enemas may be too difficult to perform in some patients with excessive retained gas after colonoscopy. The patients may be requested to return on the following day for the barium enema.
Personal communication, University of WA gastrointestinal imaging staff

What are the recommendations for breast-feeding patients who receive intravenous contrast for either CT or MRI examinations?

Patients who are breast-feeding, who receive either iodinated contrast or gadolinium may continue breast-feeding after the examination without interruption.

References
1. http://www.radiology.ucsf.edu/instruction/abdominal/ab_handbook/05-CT_MRI_preg.html#contrast
2. Omniscan package insert, Nycomed, Princeton, NJ.
3. Kubik-Huch RA, Gottstein-Aalame NM, Frenzel T, et al. Excretion of gadopentetate dimeglumine into human breast milk during lactation. Radiology 2000; 216: 555-558.
4. Mutzel W, Speck U. Pharmacokinetics and biotransformation of iohexol in the rat and the dog. Acta Radiol Suppl. 1980; 362: 87-92.
5. Webb JA, Thomsen HS, Morcos SK; Members of Contrast Media Safety Committee of European Society of Urogenital Radiology (ESUR). The use of iodinated and gadolinium contrast media during pregnancy and lactation. Eur Radiol 2005; 15: 1234-1240.
6. Ito S. Drug therapy: Drug therapy for breast-feeding women. N Engl J Med 2000; 343: 118-126.

Which procedures require that patients have coagulation studies drawn prior to the procedure?

Angiograms
Angioplasty
Arteriovenous fistulogram
Arthrograms (IF patient is on blood thinners)
Biliary drain
Biopsies
Central line placement (permanent or temporary)
Cholangiograms (percutaneous)
Cryoplasty
Dialysis catheter placement (permanent or temporary)
Drains and chest tubes
Embolization and chemo-embolization
Epidural steroid injection
IVC filters
Kyphoplasty
Lumbar puncture
Myelogram
Nephrostomy
Nerve root block
Paracentesis
PICC placement
Pyelogram (antegrade)
Radiofrequency ablation
Thoracentesis
Ureteral stents
Vascular stents and stent grafts
Venograms
Vertebroplasty

Which medications should be discontinued prior to an invasive radiologic procedure?

• Patients should stop taking Coumadin 5 days prior to any such procedure. For all such patients on Coumadin, coagulation studies should then be ordered on the day of procedure, including a PT/INR.

• Low molecular weight heparin should not be administered less than 24 hours prior to the procedure.

• For core biopsies only, patients should also stop the following 5 days prior: aspirin, non-steroidal anti-inflammatory drugs (NSAID’s), Plavix, garlic pills, and gingko supplements. Thyroid fine needle aspirations and all non-biopsy procedures are exempt from this last condition.

Is it safe for patients with renal failure to receive gadolinium intravenously for contrast-enhanced MRI examinations?

With more data coming in regarding the incidence of Nephrogenic Systemic Fibrosis (NSF) in patients with renal insufficiency receiving gadolinium-based contrast agent, the FDA recently issued an update to their public health advisory, advising caution with patients with moderate to end-stage renal disease. In light of this data, as well as more research data from radiology journals, the following policy has been adopted in our radiology department for now:

MRI technologists will be screening for patients with certain risk factors for receiving gadolinium contrast. These include:

Age greater than 65 years.
Personal or family history of any kidney disease.
Diabetes
Hypertension
Paraproteinemia syndromes such as multiple myeloma
Collagen vascular diseases: lupus, scleroderma, or rheumatoid arthritis.
Nephrotoxic medications such as chemotherapy and long-term non-steroidal anti-inflammatory drugs (NSAID’s).

MRI technologists will be checking for creatinine levels by the following criteria:

Existing lab results will be checked for the most recent Cr level for ALL patients that may receive gadolinium. Patients scheduled for non-contrast exams will be exempt from this requirement.
For those patients with one or more of the above risk factors, a Cr level within the last 30 days would be sufficient. These patients would also need to sign a consent form regarding the potential risk of gadolinium solution.
If a Cr level is not available, then it needs to be determined by a blood draw prior to performing the gadolinium-enhanced exam. The order for the Cr level will need to come from the referring physician’s office.
From the Cr level, an estimated glomerular filtration rate (GFR) will then be determined.

Estimated GFR will then dictate gadolinium dosage by the following criteria:

GFR is 60 mL/min/1.73 m2 or higher (National Kidney Foundation stages 1 or 2 chronic kidney disease): no restrictions.
GFR is 30-59 mL/min/1.73 m2 (stage 3 chronic kidney disease): use minimum dose of gadolinium (20 mL).
GFR is less than 30 mL/min/1.73 m2 (stages 4 and 5 chronic kidney disease): gadolinium is NOT recommended, unless the patient is on hemodialysis.

Hemodialysis patients should have a dialysis session within 24 hours of gadolinium administration. Of note, peritoneal dialysis has been shown to be ineffective in removing gadolinium from the body.

The above guidelines are not iron-clad, and can be modified on a case-by-case basis following discussions between the attending radiologist and referring clinician regarding the relative benefits and risks of administering gadolinium.

References:
Kanal et al. ACR Guidance Document for Safe MR Practices 2007. AJR 2007; 188: 1-27.

Food and Drug Administration Center for Drug Evaluation and Research. Public health advisory. Update on MRI contrast agents containing gadolinium and nephrogenic fibrosing dermopathy. Available at: www.fda.gov/cder/drug/advisory/gadolinium_agents_20061222.htm.

Sadowski et al. Nephrogenic Systemic Fibrosis: Risk Factors and Incidence Estimation. Radiology 2007; 243: 149-157.

What is the recommended imaging study for evaluation of pulmonary embolus in pregnant patients?

Computed tomography makes use of ionizing radiation, which should be avoided when possible, especially in pregnant patients, and especially in the first trimester of pregnancy. However, when absolutely necessary, pulmonary CTA (CT angiography) is the preferred method of radiologic evaluation for pulmonary embolus in pregnant patients, provided that no contra-indications to iodinated contrast are present. It is unlikely that a single CT examination will lead to serious adverse outcomes to the fetus. The use of iodinated contrast in pregnant patients has not been shown to be associated with adverse outcomes.

References:
1. McColl MD, Ramsay JE, Tait RC, et al. Risk factors for pregnancy associated venous thromboembolism. Thromb Haemost 1997;78:1183-8.
2. Gherman RB, Goodwin TM, Leung B, et al. Incidence, clinical characteristics, and timing of objectively diagnosed venous thromboembolism     during pregnancy. Obstet Gynecol 1999;94:730-4.
3. Ros HS, Lichtenstein P, Bellocco R, et al. Pulmonary embolism and stroke in relation to pregnancy: how can high-risk women be identified? Am J     Obstet Gynecol 2002;186:198-203.
4. British Thoracic Society Standards of Care Committee Pulmonary Embolism Guideline Development Group. British Thoracic Society guidelines for     the management of suspected acute pulmonary embolism. Thorax 2003; 58: 470-483.
5. Hayashino Y, Goto M, Noguchi Y, Fukui T. Ventilation-perfusion scanning and helical CT in suspected pulmonary embolism: meta-analysis of     diagnostic performance. Radiology 2005; 234: 740-748.
6. Quiroz R, Kucher N, Zou KH, Kipfmueller F, Costello P, Goldhaber SZ, Schoepf UJ. Clinical validity of a negative computed tomography scan in     patients with suspected pulmonary embolism: a systematic review. JAMA 2005; 293: 2012-7.
7. Chan WS, Ray JG, Murray S, Coady GE, Coates, G, Ginsberg, JS. Suspected pulmonary embolism in pregnancy: Clinical presentation, results of     lung scanning, and subsequent maternal and pediatric outcomes. Arch Intern Med 2002; 162: 1170-1175.
8. Winer-Muram HT, Boone JM, Brown HL, Jennings SG, Mabie WC, Lombardo GT. Pulmonary embolism in pregnant patients: fetal radiation dose     with helical CT. Radiology. 2002; 224: 487-92.
9. Russell JR, Stabin MG, Sparks RB, et al. Radiation absorbed dose to the embryo/fetus from radiopharmaceuticals. Health Phys 1997; 73:756-769.
10. Hammer-Jacobsen E. Therapeutic abortion on account of x-ray examination during pregnancy. Danish Med Bull 1959; 6: 113-122.
11. Hall EJ. Radiobiology for the radiologist, 4th ed. Philadelphia: Lippincott; 1994: 363-452.
12. Wagner LK, Archer BR, Zeck OF. Conceptus dose from two state-of-the-art CT scanners. Radiology 1986; 159: 787-792.
13. Bushberg JT, Seibert JA, Leidholdt EM, Boone JM. The essential physics of medical imaging. Williams and Wilkins, Baltimore, 1994; 694.
14. Nelson JA, Livingston JC, Moon RG. Mutagenic evaluation of radiographic contrast media. Invest Radiol 1982; 17: 183-185.
15. Morisetti A, Tirone P, Luzzani F, de Haen C. Toxicologic safety assessment of iomeprol, a new x-ray contrast agent. Eur J Radiol 1994; 18     (Suppl 1): 21-31.
16. Ralston WH, Robbins MS, James P. Reproductive, developmental, and genetic toxicity of ioversol. Invest Radiol 1989; 24 (Suppl 1): 16-22.
17. desch F, Camus M, Ermans AM, et al. Adverse effects of amniofetography on fetal thyroid function. Am J Obstet Gynecol 1976; 126: 723-726.
18. na G, Zaffaroni M, Defilippi C, et al. Effects of iopamidol on neonatal thyroid function. Eur J Radiol 1992; 12: 22-25.
19. Webb JA, Thomsen HS, Morcos SK; Members of Contrast Media Safety Committee of European Society of Urogenital Radiology (ESUR). The     use of iodinated and gadolinium contrast media during pregnancy and lactation. Eur Radiol 2005; 15: 1234-1240.

What is the imaging protocol for palpable breast masses?

Evaluation of a palpable breast mass in a female

Age	Imaging Protocol
<20	Ultrasound only
20-29	Ultrasound Diagnostic mammogram of symptomatic breast(s)
30-35	Same as 20-30
30-35 & mother or sister w/history of breast cancer	Same as >35
>35	Bilateral diagnostic mammograms Ultrasound of symptomatic breast

Evaluation of a palpable breast mass in a male

Age	Imaging Protocol
<20	Ultrasound only
>20	Bilateral diagnostic mammogram

What is the policy regarding elevated creatinine levels and intravenous contrast for CT scans?

If serum Cr <1.6, proceed with intravenous contrast.
If serum Cr is 1.7 to 1.9, take Mucomyst 600 mg PO BID the day before and the day of the exam.
If serum Cr is >1.9, nephrology consult is recommended before intravenous contrast.
Also, no more than 1 study with iodinated contrast is recommended in a 24 hour period.

How do you decide if a patient is a suitable candidate for CT angiography examinations? see chart here

Studies have shown that interpretation of CTA examinations is limited by vessel calcifications. Patients with diabetes, coexisting cardiac disease, and age greater than 80 have been shown to have a sufficient degree of vascular calcifications that would limit CTA. Also, patients with certain degrees of renal insufficiency may be better served by an MRA examination rather than CTA. This flowchart outlines our basic approach to screening patients for CTA examination:

What coagulation cutoff parameters do you use for invasive radiological prodedures?

In general, platelets > 100, PT/INR > 1.5, and PTT > 45. These parameters may be modified on a case by case basis at the radiologist's discretion.

Which types of intravenous acess are suitable for the administration of contrast materials?

For most contrast-enhanced CT and MR exams, a 22-gauge or larger IV is preferable, but a 24 gauge IV may be adequate for hand injections. For CT angiography exams (e.g. rule out PE, peripheral runoffs), as well as multiphase CT exams (e.g. liver and pancreas protocol exams), an 18-gauge IV is preferred given the higher injection rates of contrast.

Tunneled catheters and PICC's are in general not approved for power injector use. However, Power Port's and Power PICC's manufactured by Bard are approved for use with power injectors. If you are interested in these products, you should consult with the surgeon or intravenous therapy team at your institution regarding their availability.