Incidental findings on cone beam computed tomographic images: a Pandora's box?

Abstract

In the closing weeks of 2013, my colleague Dr Allan G. Farman kindly shared cone beam computed tomographic (CBCT) images of a patient who had presented to our facility for cross-sectional imaging of potential implant sites. His concern was not with the implant recipient sites, nor with the jaws, nor even with the maxillofacial skeleton, but rather with an intraosseous entity he had identified in the base of the skull. Specifically, it presented as an osseous corticated intracranial superoinferior pouching defect in the midsagittal of the osseous slope of the basiocciput of the clivus. Without hesitation, we both knew what we were dealing with—an indeterminate incidental finding. The generic term incidental finding is applied in radiology to describe an occult entity discovered unexpectedly on an imaging examination performed for an unrelated reason. An incidental finding is sometimes referred to as an incidentaloma. However, this is often a misnomer, as the suffix -oma suggests that the finding is a tumor. Some incidental findings may be easily identified based on radiologic presentation and location (e.g., tonsilloliths), whereas others, as in the case described above, may be indeterminate and present as radiologic diagnostic dilemmas. It is also not uncommon for many physiologic features, normal variants, minor developmental anomalies, and imaging artifacts to be misidentified as potential pathology by untrained or inexperienced observers. Such misidentification may result in unnecessary concern for the patient, as well as inappropriate and costly supplemental tests and imaging. One area that has received little attention in oral and maxillofacial (OMF) CBCT imaging thus far is the consideration of the professional, ethical, clinical, and legal issues involved in the recognition and management of incidental findings, particularly those for which diagnosis is indeterminate. The availability and use of CBCT imaging continues to expand into all areas of dentistry, giving rise to more and more imaging studies. Not surprisingly, the growing number of these studies is partly responsible for a commensurate increase in incidental findings. However, other factors, such as the greater image resolution, increased knowledge of practitioners, and heightened awareness of medicolegal issues, also contribute to the perceived rise in incidental findings. It is clear that as the number of clinicians who own and operate CBCT equipment and interpret their own images continues to overshadow those with formal training in OMF radiology, guidance on recognition, interpretation, and appropriate management of these findings is necessary. The prevalence of incidentalomas in imaging diagnostic tests in medical radiology is surprisingly high. Lumbreras et al.1Lumbreras B. Donat L. Hernández-Aguado I. Incidental findings in imaging diagnostic tests: a systematic review.Br J Radiol. 2010; 83: 276-289Crossref PubMed Scopus (218) Google Scholar recently performed a systematic review of the available evidence on the frequency and management of incidental findings in medical imaging diagnostic tests. From the 26 included computed tomography (CT) articles, they found the mean frequency of incidental findings was 31.1% (95% CI, 20.1%-41.9%). They proposed a simplistic, albeit subjective, classification system of the incidental findings according to their clinical importance: major, moderate, and minor. Concerning advanced imaging involving the head, 2 recent studies have quantified the prevalence of significant findings from a medical radiology perspective. In the largest study to date, involving almost 16 000 CT scans of children involved in blunt trauma, Rogers et al.2Rogers A.J. Maher C.O. Schunk J.E. et al.Pediatric Emergency Care Applied Research Network. Incidental findings in children with blunt head trauma evaluated with cranial CT scans.Pediatrics. 2013; 132: e356-e363Crossref PubMed Scopus (38) Google Scholar reported that 4% (95% CI, 3.8%-4.5%) of children had incidental findings on their CT scans unrelated to their injury, of whom 4% required immediate attention (tumors), 26% required follow-up (mainly sinus conditions), and the remaining 70% presented with insignificant additional findings. Concern among the professional radiology community in the United States has reached a level where various white papers have been developed to provide guidance to radiologists on specific topics such as abdominal,3Berland L.L. Silverman S.G. Gore R.M. et al.Managing incidental findings on abdominal CT: white paper of the ACR incidental findings committee.J Am Coll Radiol. 2010; 7: 754-773Abstract Full Text Full Text PDF PubMed Scopus (609) Google Scholar adnexal,4Patel M.D. Ascher S.M. Paspulati R.M. et al.Managing incidental findings on abdominal and pelvic CT and MRI, part 1: white paper of the ACR Incidental Findings Committee II on adnexal findings.J Am Coll Radiol. 2013; 10: 675-681Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar vascular,5Khosa F. Krinsky G. Macari M. Yucel E.K. Berland L.L. Managing incidental findings on abdominal and pelvic CT and MRI, part 2: white paper of the ACR Incidental Findings Committee II on vascular findings.J Am Coll Radiol. 2013; 10: 789-794Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar splenic,6Heller M.T. Harisinghani M. Neitlich J.D. Yeghiayan P. Berland L.L. Managing incidental findings on abdominal and pelvic CT and MRI, part 3: white paper of the ACR Incidental Findings Committee II on splenic and nodal findings.J Am Coll Radiol. 2013; 10: 833-839Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar nodal,6Heller M.T. Harisinghani M. Neitlich J.D. Yeghiayan P. Berland L.L. Managing incidental findings on abdominal and pelvic CT and MRI, part 3: white paper of the ACR Incidental Findings Committee II on splenic and nodal findings.J Am Coll Radiol. 2013; 10: 833-839Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar and biliary7Sebastian S. Araujo C. Neitlich J.D. Berland L.L. Managing incidental findings on abdominal and pelvic CT and MRI, part 4: white paper of the ACR Incidental Findings Committee II on gallbladder and biliary findings.J Am Coll Radiol. 2013; 10: 953-956Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar CT findings. Although not specifically pertinent to OMF radiology, they do provide a methodology incorporating classification based on description of the lesion and algorithms with steps that involve further data gathering to affect management (e.g., categorization, demographics, history) or action (e.g., performing an additional imaging study, following up, or intervening with a biopsy or surgery). The identification of incidental findings on the images of research participants has received particular attention8Ballantyne C. To know or not to know.Nat Med. 2008; 14: 797Google Scholar from not only the medical9Booth T.C. Jackson A. Wardlaw J.M. Taylor S.A. Waldman A.D. Incidental findings found in “healthy” volunteers during imaging performed for research: current legal and ethical implications.Br J Radiol. 2010; 83: 456-465Crossref PubMed Scopus (59) Google Scholar but also the legal10Tovino S.A. Incidental findings: a common law approach.Account Res. 2008; 15: 242-261Crossref PubMed Scopus (10) Google Scholar profession, with even the development of management pathways and disclosure recommendations.11Wolf S.M. Lawrenz F.P. Nelson C.A. et al.Managing incidental findings in human subjects research: analysis and recommendations.J L Med Ethics. 2008; 36 (211): 219-248Crossref PubMed Scopus (547) Google Scholar Without clear professional guidelines, radiologists face a dilemma. Currently there is a continuum of professional opinion as to the reporting of incidentalomas in medical radiography, representative of the thoughts of OMF radiologists. At one end of the spectrum is the concept that too much medical information is potentially harmful and that the patient would be better off not knowing all incidental findings. Those in this camp insist that radiologists should have discretion to ignore incidental findings on imaging studies if they appear benign or if the disclosure of such findings provides little or no benefit to patients and potentially exposes them to considerable psychologic distress.12Welch H.G. Schwartz L.M. Woloshin S. Overdiagnosed: Making People Sick in the Pursuit of Health. Beacon Press, Boston, MA2011: 90-101Google Scholar, 13Volk M.L. Ubel P.A. Better off not knowing: improving clinical care by limiting physician access to unsolicited diagnostic information.Arch Intern Med. 2011; 171: 487-488PubMed Google Scholar Indeed, some insist that unfiltered reporting of incidentalomas, especially among zealous practitioners, is tantamount to overdiagnosis, having the potential to harm patients by exposing them to overtreatment including supplemental imaging or clinical procedures (such as biopsy). On the opposite end of the spectrum, others contend that practitioners have the ethical and legal duty to disclose all relevant medical information to patients.14American Medical Association Council on Ethical and Judicial AffairsSection 8.082. Withholding Information from Patients.in: Code of Medical Ethics of the American Medical Association, 2010-2011. American Medical Association, Chicago, IL2010: 269-270Google Scholar In the current litigious medical environment, where patient autonomy is valued and where there is no interpretive reporting standard on what constitutes a relevant or legitimate incidental finding, subscribers to this opinion contend that the patient's “right to know” trumps all other professional considerations and that it is ultimately for the patient to decide on how much risk they themselves should tolerate. In this view, to do otherwise would be malpractice.15Brown S.D. Professional norms regarding how radiologists handle incidental findings.J Am Coll Radiol. 2013; 10: 253-257Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar Compared with advanced medical imaging modalities such as CT and magnetic resonance imaging, where soft tissue differences are discernible, one might expect CBCT imaging to be less likely to result in the identification of incidental findings. However, numerous authors have reported on the frequency of incidental findings on CBCT, and although these can vary widely depending on age groups, population studied, and category of findings, they are consistently approximately 50%.16Miles D.A. Clinical experience with cone-beam volumetric imaging report of findings in 381 cases.Comput Tomography. 2005; 20: 416-424Google Scholar, 17Cha J.Y. Mah J. Sinclair P. Incidental findings in the maxillofacial area with 3-dimensional cone-beam imaging.Am J Orthod Dentofacial Orthop. 2007; 132: 7-14Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar, 18Pliska B. DeRocher M. Larson B.E. Incidence of significant findings on CBCT scans of an orthodontic patient population.Northwest Dent. 2011; 90: 12-16PubMed Google Scholar, 19Drage N. Rogers S. Greenall C. Playle R. Incidental findings on cone beam computed tomography in orthodontic patients.J Orthod. 2013; 40: 29-37Crossref PubMed Scopus (35) Google Scholar, 20Pette G.A. Norkin F.J. Ganeles J. et al.Incidental findings from a retrospective study of 318 cone beam computed tomography consultation reports.Int J Oral Maxillofac Implants. 2012; 27: 595-603PubMed Google Scholar, 21Price J.B. Thaw K.L. Tyndall D.A. Ludlow J.B. Padilla R.J. Incidental findings from cone beam computed tomography of the maxillofacial region: a descriptive retrospective study.Clin Oral Implants Res. 2012; 23: 1261-1268Crossref PubMed Scopus (75) Google Scholar, 22Cağlayan F. Tozoğlu U. Incidental findings in the maxillofacial region detected by cone beam CT.Diagn Interv Radiol. 2012; 18: 159-163Crossref PubMed Scopus (70) Google Scholar, 23Allareddy V. Vincent S.D. Hellstein J.W. Qian F. Smoker W.R. Ruprecht A. Incidental findings on cone beam computed tomography images.Int J Dent. 2012; 2012: 871532Crossref PubMed Scopus (62) Google Scholar Considering the penetration of CBCT imaging in dental practice, most studies report findings from a relatively small sample (less than 400 participants). Only one study attempted to classify incidentalomas into groups regarding their potential clinical significance; it found that although 16.1% required follow-up or referral, this was mostly in regard to questionable periapical status.21Price J.B. Thaw K.L. Tyndall D.A. Ludlow J.B. Padilla R.J. Incidental findings from cone beam computed tomography of the maxillofacial region: a descriptive retrospective study.Clin Oral Implants Res. 2012; 23: 1261-1268Crossref PubMed Scopus (75) Google Scholar Only one study has reported for a sample size of 1000 participants, within which 3 malignancies were identified incidentally.23Allareddy V. Vincent S.D. Hellstein J.W. Qian F. Smoker W.R. Ruprecht A. Incidental findings on cone beam computed tomography images.Int J Dent. 2012; 2012: 871532Crossref PubMed Scopus (62) Google Scholar Clearly there is a need for multivariate analysis of a much larger (perhaps multicenter) study sample enrolling up to 10 000 participants to provide a clearer understanding of the prevalence of significant incidentalomas and to provide associative guidance on identification. The American College of Radiology guidelines for CT reporting24American College of Radiology. ACR practice guideline for communication of diagnostic imaging findings. 2011. Available at: http://www.acr.org/∼/media/C5D1443C9EA4424AA12477D1AD1D927D.pdf. Accessed December 30, 2013.Google Scholar form the basis for CBCT interpretive reporting. A report should have 4 essential elements including sections describing demographics, relevant clinical information, the body of the report, and radiologic impression. Incidental findings should be described as a section within the findings of the body of the report and, if potentially significant, also highlighted in the radiologic impression. In addition, it is here that follow-up or additional diagnostic studies to clarify or confirm the impression should be suggested when appropriate. However, it appears that there is a general lack of agreement concerning how radiologists report incidental findings on multidetector CT.25Johnson P.T. Horton K.M. Megibow A.J. Jeffrey R.B. Fishman E.K. Common incidental findings on MDCT: survey of radiologist recommendations for patient management.J Am Coll Radiol. 2011; 8: 762-767Abstract Full Text Full Text PDF PubMed Scopus (48) Google Scholar I suspect that the same is true for CBCT reports. This may be due, at least in part, to a lack of or inconsistency in standards in disclosing or reporting incidental findings. Given that there is no consensus guideline providing those who perform and interpret CBCT images with a “usual and customary manner” in which to deal with incidental findings, practitioners must decide for themselves how to deal with them. I believe that practitioners have a responsibility to develop individual management protocols to deal with unexpected findings in CBCT imaging. Based on my professional experience since 2004, my personal protocol involves 3 strategies. The first strategy involves a conscientious effort to systematically review the entire CBCT volumetric dataset and report on relevant findings. Numerous medical24American College of Radiology. ACR practice guideline for communication of diagnostic imaging findings. 2011. Available at: http://www.acr.org/∼/media/C5D1443C9EA4424AA12477D1AD1D927D.pdf. Accessed December 30, 2013.Google Scholar, 26Board of Faculty of Clinical Radiology, Royal College of radiologists. Standards for the Reporting and Interpretation of Imaging Investigations. London, England: Royal College of Radiologists; January 2006. Available at: http://www.rcr.ac.uk/docs/radiology/pdf/StandardsforReportingandInetrpwebvers.pdf. Accessed December 31, 2013.Google Scholar professional body guidelines recommend that all imaging procedures, and now specifically CBCT,27Carter L. Farman A.G. Geist J. et al.American Academy of Oral and Maxillofacial Radiology. American Academy of Oral and Maxillofacial Radiology executive opinion statement on performing and interpreting diagnostic cone beam computed tomography.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008; 106: 561-562Abstract Full Text Full Text PDF PubMed Scopus (136) Google Scholar should include an expert opinion from a radiologist, given by means of a written report or comment. Although some discrepancies, such as omissions of insignificant findings, typographical errors, and errors in interpretive opinion, are likely to occur, frank errors (including exclusion of obvious overt findings of significance and lack of description of incidental findings of potentially moderate to high significance), while inevitable, must be minimized. Workload can be a significant factor in increasing the likelihood of errors in CBCT. “Reckless reads,” in which too many cases are viewed superficially, potentially have great legal implications.28Berlin L. Liability of interpreting too many radiographs.AJR Am J Roentgenol. 2000; 175: 17-22Crossref PubMed Scopus (43) Google Scholar Comprehensive radiologic assessment and interpretation takes time and must be considered integral to the performance of CBCT imaging. The second strategy involves familiarity with the incidence, location, and presentation of common incidentalomas. Depending on experience and training, this knowledge base will vary for each practitioner. Practitioners are strongly advised to become familiar with the current scientific literature (e.g., case reports and series in journals; books) and attend continuing dental education courses on CBCT interpretation, such as the certification training offered by the American Dental Association (ADA) and sponsored by the American Academy of Oral and Maxillofacial Radiology (AAOMR), held annually at the ADA Annual Session and now mid-yearly at ADA headquarters in Chicago, IL, USA. These courses offer opportunities at developing baseline competency in understanding the relative incidence and radiographic features of the more common incidental findings, as well as opportunities to network with OMF radiologists. The third and final management strategy when an incidental finding remains indeterminate and becomes a diagnostic dilemma is not to continue to act alone but rather to invoke the “call a friend” option, as demonstrated in the worldwide television game show “Who Wants to be a Millionaire.” This is just as true for generalists and other dental specialists as it is for OMF radiologists. Referral should be to a board-certified OMF radiologist first or, if that option is unavailable, an oral pathologist with expertise in advanced imaging. This is likely the most cost-effective referral route, because these individuals usually have a wealth of experience and expertise on which to draw. The practice of providing specific image screenshots for comment, although likened by many to a “corridor consultation,” is akin to handicapping the radiologist, not to mention now being a litigious minefield, especially if the images are forwarded as an e-mail attachment. An opinion request should always be accompanied by inclusion of the entire volumetric dataset. It should be recognized that the OMF radiology professional network is extensive and that OMF radiologists readily seek the opinions of colleagues including head and neck and neuroradiologists. I believe that an essential role of the OMF radiologist is to act as a collaborative resource for clinicians to assist in determining the nature of an incidental imaging feature (whether it is normal, an anatomic variant, or a finding with a low, intermediate, or high level of potential significance) and in guiding appropriate management follow-up. Management options include ignoring the feature (in the case of identification), comparison with available prior relevant imaging examinations, correlation with current clinical presentation, recommendations for further evaluation, and periodic surveillance (observing until some change or threshold is reached). This is often communicated within the written radiologic interpretation report and clarified by telephone conversations or e-mail. Although many practitioners are aware of the prevalence of incidental findings in specific groups, currently this relationship has no roadmap—no consensus direction on the most appropriate management protocol. Professional recommendations, with input from specific specialties and disciplines, are needed to develop clinical decision management algorithms for specific incidentalomas such as the asymptomatic presence of chronic apical periodontitis on root canal filled teeth, asymmetric intracranial calcifications, sinus opacifications, and vertebral entities. One such algorithm has recently been published for the management of the incidental finding of calcified carotid artery atheroma on dental images.29MacDonald D. Chan A. Harris A. Vertinsky T. Farman A.G. Scarfe W.C. Diagnosis and management of calcified carotid artery atheroma: dental perspectives.Oral Surg Oral Med Oral Pathol Oral Radiol. 2012; 114: 533-547Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar So what was the entity that sparked this opining? After Dr Farman and I discussed the case, the anonymous volume was provided by HIPAA (Health Insurance Portability and Accountability Act)–compliant internet transfer to selected colleagues in OMF radiology and neuroradiology for their consideration. Based on this feedback, an extensive differential was developed, including anatomic variations (incomplete basilar transverse segmentation fissure), developmental issues (intraosseous neurenteric cyst, arachnoid herniations, bony cleft of canalis basilaris medianus, meningocele, clival ecchordosis physaliphora) nonneoplastic masses (chordoma), and neoplastic masses (chondrosarcoma, metastasis, lymphoma, meningioma). Because no diagnostic consensus was achieved that would suggest that the finding was innocuous, an interpretive report was sent to the clinician requesting correlation with available information, such as clinical history and current signs and symptoms, along with a recommendation that additional imaging (most likely magnetic resonance imaging) identifying the soft tissue contents of the cleft be performed to establish the entity as a benign condition and differentiate it from other clival lesions. This was followed up with confirmation of receipt of the report and verification from the practitioner that the results and recommendations would be conveyed to the patient. This experience illustrates that although the democratization of maxillofacial CBCT in dentistry has opened a Pandora's box of incidental findings, OMF radiologists serve to provide clinicians with valuable expertise and have extensive familiarity in identifying and managing these entities.