EXPEDITED REVIEW: EDITORIAL COMMENT
Noncardiac Abnormalities in Diagnostic Cardiac Computed Tomography
Within Normal Limits or We Never Looked!*
John A. Rumberger, PhD, MD, FACC*
The Ohio State University, HealthWISE Wellness Diagnostic Center, Dublin, Ohio
* Reprint requests and correspondence: Dr. John A. Rumberger, The Ohio State University, HealthWISE Wellness Diagnostic Center, 5747 Perimeter Drive, Suite 105, Dublin, Ohio 43017. (Email: jrumberger{at}healthwisecenter.com).
Noncontrast cardiac computed tomography (electron beam tomography [EBT] and multidetector computed tomography [MDCT]) for the definition of coronary artery calcium score has been shown to be of value in defining individualized cardiac risk, over and above population-based, conventional risk factors (1,2). This is considered to be screening by some clinicians and justified for refinement of individual risk by others (3). Regardless, such imaging studies include all structures within the pericardium and at least a portion of the surrounding lung, aorta, and chest—depending on the chosen image reconstruction field of view. Because the entire chest is irradiated with such procedures, reconstructing images of the heart and then reconstructing images of the chest as a whole provides no additional radiation to the patient. Controversies abound about whether the lungs and chest should be formally reviewed on these screening "heart scans." Although I have personal opinions about what should be done (which form the foundations for the subsequent discussion), they are not universally shared by colleagues who also perform cardiac and cardiovascular screening.
Contrast-enhanced cardiac CT scans are becoming more common, literally worldwide, as diagnostic tools after literally scores of studies (originally investigated and validated in Germany [4] and in the U.S. [5] using EBT). As cardiac CT has become more sophisticated, the latest generation of 64-slice MDCT have now shown the greatest promise in defining not only focal coronary stenoses but also calcified and noncalcified (6) plaque. Such studies are not done for screening purposes, but as part of a diagnostic workup, generally in a patient with symptoms caused by a potential cardiovascular origin or to clarify potential pathology from other tests (e.g., echocardiography, perfusion imaging, and invasive angiography). Because common symptoms such as "chest pain" and "shortness of breath" are not universally accounted for by purely cardiac causes, diagnostic contrast-enhanced chest CT is often used as a "triple rule-out," i.e., looking for the three most deadly causes of such symptoms—myocardial ischemia/infarction, aortic dissection, and pulmonary embolism. Of course, because part of the structures are included in the radiation field, review of the images is needed for less immediately life-threatening, but still important, associated diagnoses such as pneumonia, diagrammatic hernia, and pericardial disease.
In the cases of the triple rule-out using contrast-enhanced chest CT, it would be appropriate to include a team approach—using the interpretive skills of individuals trained in cardiologic and radiographic imaging. However, as the use of cardiac CT for a variety of purposes (using EBT or MDCT) grows (almost exponentially if the number of "training" course offered by various professional societies and/or private concerns is a fair measure), it is not clear whether the approach of reviewing the images for cardiac and noncardiac findings is being universally taught or applied in practice.
The paper in this issue of the Journal by Onuma et al. (7) on defining noncardiac findings in cardiac CT brings these issues to the forefront. As a cardiovascular disease specialist, I have focused much of my professional career, spanning now more than 20 years, on the development of cardiac CT and its application to clinical practice. I have also had the privilege, as an admitted "interloper" in the world of radiology, to sit beside and interact, cajole, learn, and be guided by colleagues who were pioneers and remain leaders in this application of radiological sciences. As such, I have some comments to make about looking "outside the box" of the heart into the chest and adjacent structures to complete the image review and to provide the best care to patients. These comments revolve around three aspects that are interrelated, but still separate: medico-legal, medico-moral, and medico-economic.
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Medico-Legal
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Hunold et al. (8) in a "screening" population from Germany found that 53% of 1,812 patients had at least one noncardiac finding using EBT. The current study by Onuma et al. (7) found the prevalence to be 58%, although 52% were either current (13%) or former (39%) smokers. A study by Horton et al. (9) looked at a screening population of 1,326 in Baltimore and found a much lower incidence of pulmonary abnormalities, with only 7.8% requiring clinical or radiologic follow-up. In the latter study, only 25% of the cohort had a smoking history. However, the prevalence of active smokers in Europe and Japan is not necessarily greater than the current 24% in the U.S. (10). Additionally, the high prevalence of heart disease in the U.S. is especially important in former smokers, and the potential for lung cancer development is relatively high for at least 10 years (and potentially up to 20 years) after cessation. Although in the short follow-up from the Onuma study only 8% (a total of 4) had malignancies (2 lung cancers and 2 breast cancers), the missing of even one cancer is clinically unacceptable. Additionally, "failure to diagnose" remains one of the most common issues in malpractice cases. Also of major clinical importance, Onuma et al. (7) showed that in 32 of 201 patients in whom coronary disease was ruled out, noncardiac findings by CT were considered sufficient to explain the symptoms.
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Medico-Moral
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I cannot imagine that any cardiologist would look only at the heart on a chest radiograph. It is the obligation of the clinician or the summation of the clinicians involved in any medical case to ensure that all data available are reviewed. Of course, this may depend on the diagnostic capability of the tests available. For instance, standard cardiac myocardial perfusion imaging is simply not of sufficient quality to be diagnostic of surrounding pulmonary structures. Thus, no accountability is expected for areas outside the target. The same can be said for other methods, such as echocardiography and even cardiac catheterization. However, CT is diagnostic. The required high-resolution, thin-sectioning imaging for contrast-enhanced cardiac CT is sufficient for general noncardiac body diagnostics. It is thus the contention that medico-moral (obligatory) situations would implicate viewing all images and areas irradiated as diagnostic of potential pathology.
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Medico-Economic
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There are a number of discussions related to the potential medico-economic issues of screening. That is the situation in which a heart scan was performed to define coronary calcification and an incidental finding was a small pulmonary nodule. Many academic discussions then define the downstream testing that might follow an obligatory workup for that nodule. Most of these end up with the potential scenario of biopsies being done on benign lesions. Such statements are generally hyperbole, just as the farcical comments by some related to finding coronary calcium and "unnecessary" cardiac catheterizations. There are simply no data to support these fanatical downstream economic projects that would ostensibly bankrupt the insurance companies.
There are published guidelines on what to do with positive CT coronary calcium studies (11) that are almost universally applied, and there are also published guidelines as to what to do with pulmonary nodules found in CT scans performed in smokers and nonsmokers (12). None of these guidelines suggest cardiac catheterization or lung biopsy, respectively, as an initial approach to abnormal studies. To put it simply, diagnostic imaging is just that: diagnostic; it may or may not require confirmation of other diagnostic modalities, but the responsible clinician will proceed with such workup in the most economical, but legal and moral, manner. I often end my lectures that discuss cost effectiveness with this poignant remark: "Cost effectiveness in medicine often depends on whose life is being saved, mine or somebody else’s."
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Conclusions
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We all learned as medical students or residents the shortcut to use in the medical record noting certain areas of the physical examination as WNL. Of course this was shorthand for within normal limits; however, with the expanding role of cardiovascular CT and radiation and imaging of both the target areas as well as other structures, we simply cannot tolerate for legal, moral, and economic reasons to use the other meaning of within normal limits: we never looked.
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Footnotes
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Dr. Rumberger has received a grant from the National Institutes of Health and is currently on the KOS Pharma Speakers Bureau.
* Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology. 
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References
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- Arad Y, Goodman KJ, Roth M, Newstein D, Guerci AD. Coronary calcification, coronary disease risk factors, C-reactive protein, and atherosclerotic cardiovascular disease events J Am Coll Cardiol 2005;46:158-165.[Abstract/Free Full Text]
- LaMonte M, FitzGerald SJ, Church TS, et al. Coronary artery calcium score and coronary heart disease events in a large cohort of asymptomatic men and women Am J Epidemiol 2005;162:1-9.[Free Full Text]
- Greenland P, LaBree L, Azen SP, Doherty TM, Detrano RC. Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals JAMA 2004;291:210-215.[Abstract/Free Full Text]
- Moshage WE, Achenbach S, Seese B. Coronary artery stenosisthree-dimensional imaging with electrocardiographically triggered contrast agent enhanced, electron-beam CT. Radiology 1995;196:707-714.[Abstract/Free Full Text]
- Schmermund A, Rensing BJ, Sheedy PF, Bell MR, Rumberger JA. Intravenous electron-beam CT coronary angiography for segmental analysis of coronary artery stenoses J Am Coll Cardiol 1998;31:1547-1554.[Abstract/Free Full Text]
- Leber AW, Becker A, Knez A, et al. Accuracy of 64-slice computed tomography to classify and quantify plaque volumes in the proximal coronary systema comparative study using intravascular ultrasound. J Am Coll Cardiol 2006;47:672-677.[Abstract/Free Full Text]
- Onuma Y, Tanabe K, Nakazawa G, et al. Noncardiac findings in cardiac imaging with multidetector computed tomography J Am Coll Cardiol 2006;48:402-406.[Abstract/Free Full Text]
- Hunold P, Schmermund A, Seibel RM, Grönemeyer DH, Erbel R. Prevalence and clinical significance of accidental findings in electron-beam tomographic scans for coronary artery calcification Eur Heart J 2001;22:1748-1758.[Abstract/Free Full Text]
- Horton KM, Post WS, Blumenthal RS, Fishman EK. Prevalence of significant noncardiac findings on electron-beam computed tomography coronary artery calcium screening examinations Circulation 2002;106:532-534.[Abstract/Free Full Text]
- Reeves MJ, Rafferty AP. Healthy lifestyle characteristics among adults in the United States, 2000 Arch Intern Med 2005;165:854-859.[Abstract/Free Full Text]
- Rumberger JA, Brundage BH, Rader DJ, Kondos G. Electron beam CT coronary calcium scanninga review and guidelines for use in asymptomatic individuals. Mayo Clin Proc 1999;74:243-252.[ISI][Medline]
- MacMahon H, Bao B, Austin JHM, et al. Guidelines for the management of small pulmonary nodules detected on CT scansa statement from the Fleischner Society. Radiology 2005;237:395-400.[Abstract/Free Full Text]
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- Noncardiac Findings in Cardiac Imaging With Multidetector Computed Tomography
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Medico-Legal
Medico-Moral