SummaryMontefiore Medical Center uses a simple algorithm to promote appropriate use of imaging tests for stable emergency department patients with suspected pulmonary embolism, with the goal of promoting patient safety by reducing unnecessary radiation exposure for patients. The algorithm recommends that physicians order and review results from an initial chest x-ray for all these patients. For those with a normal result in need of additional imaging, the algorithm suggests a ventilation-perfusion scan. This test involves less radiation than the more commonly used computed tomography pulmonary angiography, which under the algorithm is used only for patients with abnormal x-ray results. The program has various systems in place to assist physicians in following the algorithm, including phone calls and e-mails from senior radiology department leaders when orders deviate from the algorithm, along with ongoing tracking of false negative tests (an indicator of quality of care). The program reduced use of pulmonary angiography and increased use of ventilation-perfusion scans, leading to less radiation exposure for patients without negatively affecting outcomes.Moderate: The evidence consists of pre- and post-implementation comparisons of the use of computed tomography (CT) pulmonary angiography and ventilation-perfusion (V/Q) scans, estimates of per-patient radiation exposure, and the percentage of false negative results for each type of test.
Developing OrganizationsMontefiore Medical Center
Date First Implemented2007
Vulnerable Populations > Urban populations
Problem AddressedEmergency department (ED) physicians routinely order computed tomography (CT) pulmonary angiography for patients with suspected pulmonary embolism (PE). Although an effective diagnostic tool, this test can unnecessarily expose patients to high doses of radiation, which has been highlighted as an important patient safety issue. Ventilation-perfusion (V/Q) scanning, an equally effective alternative that involves less radiation, tends to be underutilized.
- Increased use of CT pulmonary angiography: In the 1980s and early 1990s, V/Q scanning served as the main imaging test for detecting PE. However, the widespread availability of CT pulmonary angiography has led to a rapid increase in its use over the past several decades, with a concomitant decline in use of V/Q scanning.1
- Contributing to high radiation exposure for patients: CT pulmonary angiography exposes the patient to roughly five times more radiation than does V/Q scanning, with radiation exposure being 20 to 40 times greater for the female breast.2 Increased use of CT pulmonary angiography contributes to the larger trend toward increased overall radiation exposure for patients. The per capita effective dose of radiation from medical imaging rose by 600 percent between 1980 and 2006, from 0.54 millisieverts (mSv) to 3.2 mSv.3 The World Health Organization has identified medical radiation exposure as an important patient safety issue,4 as has the U.S. Food and Drug Administration, calling for safer use of imaging technologies and clinical decision support tools to assist providers in making appropriate decisions about ordering imaging tests.5
- V/Q scan as an effective but underused alternative: While both diagnostic methods have similar positive predictive values6 and patients fare equally well with either test,7,8 V/Q scanning remains underutilized as an imaging technique for patients with suspected PE.
Description of the Innovative ActivityMontefiore Medical Center uses a simple algorithm to promote appropriate use of imaging tests for stable ED patients with suspected PE, with the goal of promoting patient safety by reducing unnecessary radiation exposure for patients. The algorithm recommends that physicians order and review results from an initial chest x-ray for all these patients. For those with a normal result in need of additional imaging, the algorithm suggests a V/Q scan, which involves less radiation than CT pulmonary angiography. The program has various systems in place to assist physicians in following the algorithm, including phone calls and e-mails from senior radiology department leaders when orders deviate from the algorithm, along with ongoing tracking of false negative tests. Key program elements are outlined below:
- Three-step, simple algorithm: ED physicians use a 3-step algorithm to inform ordering of imaging studies for patients with suspected PE. The algorithm represents a general guide, not a mandate, with ED physicians having the final say on which studies to use.
- Initial chest x-ray: The algorithm recommends a chest x-ray for every stable patient with a clinical suspicion of PE. Though the x-ray cannot diagnose PE and may appear normal even if a PE exists, it can rule out other conditions that mimic the disease.
- V/Q scan for those with normal x-ray: If the chest x-ray findings are normal and the physician deems that further imaging is appropriate, the algorithm recommends a V/Q scan. In accordance with the hospital's usual clinical care, the algorithm also calls for V/Q scans for patients with contraindications to CT pulmonary angiography (regardless of chest x-ray findings), including pregnancy, contrast media allergies, and renal failure.
- CT pulmonary angiography for those with abnormal x-ray: If the chest x-ray shows certain lung problems (e.g., pleural or parenchymal abnormalities), the algorithm recommends a CT pulmonary angiography for any patient without contraindications.
- Backup test as needed: If either the V/Q scan or CT pulmonary angiography provides equivocal findings or the results seem discordant with the physician's impressions, the algorithm directs the physician to order the alternative test as well.
- Phone calls to physicians ordering CT pulmonary angiography after normal x-ray: Whenever a physician requests CT pulmonary angiography following a normal chest x-ray, a member of the radiology department phones the doctor to remind him or her of the protocol, verify that the deviation was intentional, and discuss the reason for the deviation. The ordering physician is asked to voice the reason for the deviation (e.g., there is a clinical concern for aortic dissection), but regardless of the reason, the final decision as to which test to order is left to the ED clinician.
- Followup e-mail to ED leaders after deviation from algorithm: Whenever a physician orders CT pulmonary angiography following a normal chest x-ray, radiology department leaders send an e-mail to ED leaders to describe the specific details that led to the order and verify the appropriate ordering of this test.
- Data tracking on false negatives: After 1 year, the department tallied the rate of false negative imaging results for V/Q scans and CT pulmonary angiography. (A false negative is defined as a negative imaging examination with subsequent diagnosis of PE or deep vein thrombosis within 90 days; typically about 1 percent of negative images result in false negatives.)
References/Related ArticlesStein EG, Haramati LB, Chamarthy M, et al. Success of a safe and simple algorithm to reduce use of CT pulmonary angiography in the emergency department. AJR Am J Roentgenol. 2010 Feb;194(2):392-7. [PubMed] This study, available as a free download at http://www.ajronline.org/doi/abs/10.2214/AJR.09.2499, includes a visual representation of the algorithm.
Freeman LM. Don't bury the V/Q scan: it's as good as multidetector CT angiograms with a lot less radiation exposure. J Nucl Med. 2008 Jan;49(1):5-8. Epub 2007 Dec 12. [PubMed]
Amis ES Jr, Butler PF, Applegate KE, et al. American College of Radiology white paper on radiation dose in medicine. J Am Coll Radiol. 2007 May;4(5):272-84. [PubMed]
Contact the InnovatorLinda B. Haramati, MD, MS
Director of Cardiothoracic Radiology
Montefiore Medical Center
111 E 210 St.
Bronx, NY 10467
Phone: (718) 920-7458
Innovator DisclosuresDr. Haramati has not indicated whether she has financial interests or business/professional affiliations relevant to the work described in this profile.
ResultsThe program has reduced use of CT pulmonary angiography and increased use of V/Q scans, leading to less radiation exposure for patients without negatively affecting outcomes.
Moderate: The evidence consists of pre- and post-implementation comparisons of the use of computed tomography (CT) pulmonary angiography and ventilation-perfusion (V/Q) scans, estimates of per-patient radiation exposure, and the percentage of false negative results for each type of test.
- Less use of CT pulmonary angiography, greater use of V/Q scans: The proportion of ED patients with suspected PE receiving CT pulmonary angiography decreased from 62.4 percent in 2006 (representing 1,234 patients) to 43.1 percent in 2007 (920 patients). By contrast, use of V/Q scans over the same period increased from 37.6 percent of patients in 2006 (745 patients) to 56.9 percent in 2007 (1,216 patients).
- Less radiation: The estimated mean effective dose of radiation for ED patients with suspected PE fell by 20 percent, from 8 mSv in 2006 to 6.4 mSv in 2007. The average dose for women younger than 40 fell by 32 percent over the same time period (from 7.2 mSv to 4.9 mSv). (Because measuring individual patient radiation exposure is not practical, these figures represent estimates based on an average radiation dose of 10 mSv for each CT pulmonary angiography and 2.2 mSv for each V/Q scan.)
- No significant effect on patient outcomes: The program has had virtually no impact on the likelihood of a false negative test (meaning that someone who has a PE does not get diagnosed and treated in a timely manner). A medical record review found that false negative rates for CT pulmonary angiography remained virtually unchanged, rising from 0.8 percent in 2006 (8 out of 1,046 cases) to 1.1 percent in 2007 (8 out of 753 cases). False negative rates for V/Q scans rose from 1.1 percent in 2006 (7 out of 666 cases) to 1.2 percent in 2007 (13 out of 1,087 cases). None of these differences met the threshold for statistical significance.
Context of the InnovationA 745-bed teaching hospital in the Bronx, NY affiliated with the Albert Einstein College of Medicine, Montefiore Medical Center treats about 80,000 patients a year in its ED, with x-rays, CT pulmonary angiography, and V/Q scanning available to these patients at all times. The impetus for this program came from leaders of the nuclear medicine department, who became concerned that patients were unnecessarily exposed to more radiation due to the increased use of CT scans in the last decade. Leonard M. Freeman, MD, the vice chair and chief of nuclear medicine at the Moes Division of Montefiore, became especially concerned about the issue, writing several articles on the topic. When a major study published in the New England Journal of Medicine in 2006 found that V/Q scanning was as effective as CT pulmonary angiography in diagnosing PE,6 Dr. Freeman and his staff decided to work with other hospital leaders to create a mechanism to encourage ED physicians to reduce the use of CT pulmonary angiography in clinically appropriate situations.
Planning and Development ProcessKey steps included the following:
- Interdisciplinary meetings: Leaders and senior physicians from the departments of nuclear medicine, emergency medicine, radiology, and several subsections (including cardiothoracic radiology) met monthly to talk about issues of shared concern. During 2006, they reviewed and discussed recent research on increased radiation exposure in patients and on the effectiveness of various imaging technologies used to diagnose PE.
- Algorithm development: Using the aforementioned research as background, meeting participants developed the algorithm in the fall of 2006. They decided to present it to physicians as a clinical decision support tool rather than a mandate, with physicians retaining the final say about which diagnostic approach to use (although they might be called on to explain their choice).
- Educational seminars/program rollout: In December 2006 and January 2007, the director of nuclear medicine, in collaboration with the chiefs of radiology and cardiothoracic radiology, led two hour-long seminars for ED staff, including residents and attending physicians. Participants discussed information from the literature about the relative accuracy and radiation exposure from V/Q scanning and CT pulmonary angiography. During these sessions, they received a copy of the algorithm as a handout. The protocol was subsequently agreed upon and the department was asked to begin using it.
Resources Used and Skills Needed
- Staffing: The program requires no new staff, as the team members that developed it did so as part of their regular duties, while ED physicians and radiologists participate on an ongoing basis as part of their patient care responsibilities.
- Costs: The program did not require any financial outlay by the hospital. While the cost of a V/Q scan tends to be higher than CT pulmonary angiography, insurers reimburse the hospital for both of these services. In addition, some of the increased per-patient cost presumably would be offset by the long-term reduction in radiation-related health problems.
Getting Started with This Innovation
- Take collaborative approach: The algorithm was developed through a collaborative process that included input from the leaders of three major departments (nuclear medicine, radiology, and emergency medicine). Having broad support at this level made it easier to gain the support of physicians charged with following the algorithm.
- Emphasize research basis: During educational sessions with ED physicians, spend considerable time sharing and discussing recent studies on radiation exposure and the effectiveness of V/Q scanning versus CT pulmonary angiography, with an emphasis on the long-term patient benefits from reduced radiation exposure.
- Avoid requiring adherence: ED physicians will be more likely to support the algorithm if hospital leaders present it as an optional decision support tool rather than a mandate.
Sustaining This Innovation
- Include algorithm in training of new hires: Incorporate the algorithm into the training of newly hired ED physicians and encourage them to use it, as appropriate, in their practice.
- Track and share data: Track and share data on false negative rates for each test, as this data will help to ensure ED physicians that using the algorithm does not compromise quality of care.
- Discuss deviations collegially: Discussions of the algorithm and deviations from its recommendations should occur as needed in a collegial manner.
Levin DC, Rao VM, Parker L, et al. Recent trends in utilization rates of noncardiac thoracic imaging: an example of how imaging growth might be controlled. J Am Coll Radiol. 2007;4(12):886-9. [PubMed]
Mettler FA Jr, Huda W, Yoshizumi TT, et al. Effective doses in radiology and diagnostic nuclear medicine: a catalog. Radiology. 2008;248(1):254-63. [PubMed]
Mettler FA Jr, Bhargavan M, Thomadsen BR, et al. Nuclear medicine exposure in the United States, 2005–2007: preliminary results. Semin Nucl Med. 2008;38(5):384-91. [PubMed]
Stein PD, Fowler SE, Goodman LR, et al. Multidetector computed tomography for acute pulmonary embolism. N Engl J Med. 2006;354(22):2317-27. [PubMed]
Anderson DR, Kahn SR, Rodger MA, et al. Computed tomographic pulmonary angiography vs. ventilation-perfusion lung scanning in patients with suspected pulmonary embolism: a randomized controlled trial. JAMA. 2007;298(23):2743-53. [PubMed]
Burge AJ, Freeman KD, Klapper PJ, et al. Increased diagnosis of pulmonary embolism without a corresponding decline in mortality during the CT era. Clin Radiol. 2008;63(4):381-6. Epub 2007 Dec 21. [PubMed]
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Service Delivery Innovation Profile
Original publication: November 09, 2011.
Original publication indicates the date the profile was first posted to the Innovations Exchange.
Last updated: April 17, 2013.
Last updated indicates the date the most recent changes to the profile were posted to the Innovations Exchange.
Date verified by innovator: October 17, 2012.
Date verified by innovator indicates the most recent date the innovator provided feedback during the annual review process. The innovator is invited to review, update, and verify the profile annually.