- Email: [email protected]
Gastroenterologists Should Read CT Colonography
G as tro en t ero l o g i s ts Should Read CT Colonography Steve Carpenter,
MD
KEYWORDS CT colonography Optical colonoscopy Colon cancer screening
Screening for colorectal neoplasms has become the standard of care in advanced medical settings worldwide. Identifying asymptomatic colorectal neoplastic lesions has been shown to reduce colorectal cancer incidence and the overall cost of medical care. Clinicians have several alternatives at their disposal as they consider screening for their respective patient population. Many different organizations have spent considerable time weighing the evidence to establish appropriate evidence-based guidelines directing clinicians how to appropriately manage screening; 2 important methods to consider are optical colonoscopy and computed tomographic colonography (CTC).1 The purpose of this article is to make the case that gastroenterologists should read CTC. By virtue of their training, there is no question that radiologists may provide this service competently. Gastroenterologists are well trained to detect and remove colonic abnormalities using optical colonoscopy. In training and practice, gastroenterologists develop considerable experience in colonic pathology and anatomic variation. Given this experience in three-dimensional intracolonic imaging, gastroenterologists are also well suited to interpret intracolonic images obtained via CTC. Furthermore, gastroenterologists work within a patient care infrastructure that provides a personal relationship with patients, and leads patients effectively and efficiently through their options for effective colorectal cancer screening. Central to the argument that gastroenterologists read CTC is the benefit of experience with threedimensional video-assisted colonic imaging and the physician-patient relationship. OPTICAL COLONOSCOPY
Clinicians use optical colonoscopy as a primary means to screen the entire colon not only for cancer but also for precancerous adenomatous lesions. Most adenomas may
Department of Internal Medicine, Mercer University School of Medicine, Memorial University Medical Center, 4700 Waters Avenue, Savannah, GA 31404, USA E-mail address: [email protected] Gastrointest Endoscopy Clin N Am 20 (2010) 271–277 doi:10.1016/j.giec.2010.02.006 1052-5157/10/$ – see front matter ª 2010 Published by Elsevier Inc.
giendo.theclinics.com
272
Carpenter
be removed at the time of optical colonoscopy. The size, location, shape, and pathologic nature of polyps may be determined during this single clinical encounter, providing the patient and clinician with valuable information to guide the future colorectal cancer screening strategy. Often, the clinician doing the endoscopic procedure has an established relationship with the patient and may provide recommendations regarding care at a subsequent clinical encounter. Established Centers of Digestive Health, worldwide, have proved to be successful in driving the colorectal cancer effort. Clearly, many patients and health care providers are comfortable with this protocol of patient care; however, optical colonoscopy does have its disadvantages. The procedure requires adequate colon cleansing to allow for complete mucosal evaluation, and many patients state that the arduous task of colonic preparation is a major drawback to the entire process. Often, colonoscopy requires moderate conscious sedation, requiring the clinician to reflect on the patient’s overall underlying medical condition: ‘‘Can my patient tolerate this degree of sedation?’’ From the patient’s perspective, moderate conscious sedation provides them with a comfortable medical procedure but also requires that the patient have access to reliable transportation from the medical setting. As a result, the patients not only have to absent themselves from their daily responsibilities, but their transporter must also take time from their routines to ensure safe passage home. This is a significant issue to consider when reviewing the overall cost of the colorectal cancer screening effort. During the insertion procedural phase and, if need be, polypectomy, perforation of the colon may occur. Although this is a relatively rare complication, it can and does occur in the care of asymptomatic patients. In addition, bleeding even after the most simple of polypectomies may occur and thus may require hospitalization or even administration of blood products. Because of the potential for colonic perforation, postpolypectomy bleeding, and other complications, adequately trained medical personnel must carefully discuss these possibilities to obtain meaningful informed consent from all patients before the procedure. There is simply no substitute for an excellent patient-physician relationship. Optical colonoscopy is not a perfect screening modality. Several tandem colonoscopy studies demonstrate that, for many reasons, adenomatous colon polyps may be missed during the procedure. Polyps may be behind folds, obscured by colonic debris, or simply not seen by the endoscopist. This issue has prompted considerable focus by gastrointestinal societies on quality parameters such as adenoma detection rate, cecal intubation rate, and colonoscopic withdrawal times. Many endoscopy centers have initiated routine documentation of these important quality measures and, collectively, we hope these developments can improve the overall colorectal cancer screening effort. Several studies demonstrate that adequate training and experience translate into improved quality; but we require additional experienced endoscopists. As the age of our patients increases and the population grows, we need to train more endoscopists with a firm grasp on the limitations of endoscopy and their role in the overall improvement of quality colorectal cancer screening. CT COLONOGRAPHY
CT colonography (CTC) is a promising colorectal screening tool, and several key factors make this method of colorectal cancer screening attractive to clinicians and patients. The procedure does not require moderate conscious sedation. Therefore, patients may provide their own transportation and return to work immediately following the examination, assuming the patient does not require further evaluation. As the colon is imaged digitally, the risk of procedurally related complications, such
Gastroenterologists Should Read CTC
as perforation and bleeding, is reduced. Improvements in CT technology over the years have resulted in continuous improvement in image quality and data acquisition time, and so in as little as 10 minutes, patients may have their procedure completed and be on the way back to society. Most importantly, CTC has resulted in increased patient awareness of the colorectal cancer screening effort. As CTC has received considerable attention in the lay press, more patients realize the value of cancer screening and may participate in the process; anything that increases overall patient awareness and acceptance of the process of cancer screening is beneficial. Despite these advantages, CT colonoscopy has its own problems. Many patients are disappointed to discover that CTC requires adequate colon preparation for optimal colonic imaging. In fact, the preparation is more complicated as contrast and fecal tagging agents are necessary to adequately differentiate stool from polyps. Trained medical personnel are required to describe the importance and nature of preparation to patients. Current screening recommendations suggest that some patients might have 5 or more CT examinations during their lifetime if CT is the primary colorectal cancer screening modality. Radiation exposure is inherent to the procedure, leading to increased concern about this degree of cumulative radiation exposure, but radiology societies have largely dismissed this issue.2 As a medical community, we do not fully understand the effects of medical radiation in a screening effort and long-term studies are needed. If a polyp is identified via CTC, most patients require optical colonoscopy for polyp removal. Some have suggested that small polyps may be followed with CT at shortened screening intervals. Although some patients may be comfortable with repeated CT examinations to follow a lesion, those in primary care know other patients will have concern about the safety of this watchand-wait approach. DISCUSSION
During CTC, extracolonic information is acquired.3 A standardized CT colonography reporting and data system (CRADS) has been developed and is useful for CTC report uniformity.4 Findings of major clinical relevance, categorized as E4 findings, arise in approximately 4% to 10% of CTC examinations. Examples of E4 findings include renal cell carcinoma, ovarian carcinoma, and an abdominal aortic aneurysm of worrisome size. Indeterminate extracolonic abnormalities are categorized as E3 findings in the CRADS system and are identified in approximately 30% of CTC examinations. Examples of E3 findings include suspicious renal and liver cysts. Findings of low clinical importance, such as simple liver and renal cysts, are placed in category E2. The frequency of E3 findings may be expected to increase, particularly if radiologists are liability averse. Furthermore, in a liability-concerned environment, some radiologists may be inclined to hedge on E2 abnormalities of low clinical importance, thereby increasing the percentage of E3 findings reported. Repeating scans to follow indeterminate findings will increase the overall cost of colorectal cancer screening. This is an important consideration when analyzing CTC from a cost efficacy perspective. Individual CT reports often suggest that E3 findings be followed at the discretion of the patient and referring physician. In the author’s clinical experience, patients tend to worry about any of these extracolonic findings. Time and patience is required to discuss even simple E2 findings with patients. In some cases, these discussions heighten the individual patient’s health care-related anxiety. An excellent doctor-patient relationship is useful in lessening this degree of anxiety and proves invaluable in many respects. For CTC to be clinically and cost effective, it is imperative that radiologists take great care in the nature of CTC extracolonic reporting and be prudent
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with E2 and E3 findings. Likewise, primary care physicians or gastroenterologists must communicate meaningfully with patients. Appropriately trained radiologists should interpret extracolonic findings identified at CT colonoscopy. Although interpretation of extracolonic CT images is thoroughly covered in gastroenterology training and practicing gastroenterologists review multiple CT images within a given work day, gastroenterologists do not have the expertise or privilege to provide an official interpretation of extracolonic CT data. In CTC centers, 1 prime goal is to provide the patient with the opportunity for a sameday optical colonoscopy. Within 20 or 30 minutes, a gastroenterologist reading CTC can provide an immediate intracolonic interpretation as the patient waits. There is no acute need for the extracolonic interpretation. CTC centers run by gastroenterologists can send CT images digitally and thus outsource the reading of extracolonic images. Gastroenterologists who provide CTC within their own center therefore have the opportunity to identify excellent radiologists who deliver high-quality interpretations. Small centers can even send CTC images to major university centers. Several high-quality radiologists have developed their own corporations to provide this service, allowing colorectal cancer screening centers to track the quality of extracolonic interpretations and change to an alternate vendor if necessary to ensure high-quality patient care. Extracolonic findings require careful evidence-based management. Colon cancer screenings centered in 1 locale provide patients with the opportunity to review and discuss colonic and extracolonic findings with 1 clinician in 1 sitting. Appropriate evidence-based management of all findings may be coordinated in this fashion. All members of the population should receive some form of testing to improve colorectal cancer screening outcomes. Unfortunately, this is not yet the case. There are many reasons for this lack of adherence, but some patients remain concerned about endoscopy. CTC presents patients with an alternative, as we have no perfect screening modality. Before making a decision, it is desirable that each patient has an understanding of the positive and negative attributes of available methods. Communication about the alternatives requires patience and time. A formal consultative visit can prove immensely beneficial. Although primary care physicians are perfectly suited to provide this service during routine visits, because of issues of time and the complexity of primary care, a thorough discussion is often not possible. Physicians who carefully follow the topic of colorectal screening realize that the data are far from static. Many primary care physicians are not fully versed about the sensitivity and specificity of optical colonoscopy and CTC in asymptomatic patients or the proper surveillance intervals for adenomas. Many patients are interested in discussing the data and options, and gastroenterologists are in a prime position to provide this expertise. With regard to the interpretation of colonic findings obtained during CTC, gastroenterologists have a wealth of experience with optical colonoscopy. Reading CTC flythrough images is intuitive to endoscopists. Standards for gastroenterologists performing and interpreting diagnostic CTC have been established and training programs organized by professional gastrointestinal organizations are effective in orienting endoscopists to this new technology.5 Although courses can be helpful for introduction, there is no substitute for hands-on experience; this can be achieved via mentored leader programs. Ideally, personal hands-on experience is obtained in centers providing CTC and optical colonoscopy services. Gastroenterologists may interpret colonic CTC images proficiently with accuracy similar to that of radiologists.6 Interpreting physicians must have adequate training and experience to ensure highly accurate readings. Experience and level of training directly correlate with accuracy. Colonoscopists with considerable experience with endoscopic imaging find CTC
Gastroenterologists Should Read CTC
colonic interpretation intuitive; however, there is a learning curve to acquire proficiency with the software used for CTC. Several vendors have created excellent CTC software and revision of these platforms continues. Gastroenterologists interested in CTC proficiency should select 1 software platform and learn it well. Development of expertise in CTC requires a substantial time commitment. It is reasonable to consider that CTC may become part of the gastrointestinal core curriculum for fellowship training.7 It is important that current gastroenterology fellows develop a basic familiarity with the indications, interpretation, and limitations of CTC. More in-depth training in CTC may become a reality where resources are available, requiring cooperation with departments of radiology. Some have suggested a new track within traditional gastroenterology training, wherein imaging becomes the focus and fellows would concentrate on technologies such as wireless capsule endoscopy and CTC. A comprehensive training curriculum would need to be established and training standards for current fellows developed. Established gastroenterologists who gravitate toward CTC and have an interest in interpretation must first demonstrate expertise and then make a personal commitment toward maintenance of proficiency. Radiologists require a meaningful physician peer review program for accreditation. Currently, there exists no infrastructure in gastroenterology societies for this quality control process. Randomly selected CTC studies would need to be reviewed on a regularly scheduled basis, requiring repeat reading of completed studies. Although members of one’s own organization might feasibly perform this task, this method of peer review might not result in meaningful critique. Therefore, review networks will need to be organized and the results must be readily available, with reviewers able to correlate the interpretation and original report with corresponding endoscopic and pathologic findings. Some recommend that a national database be developed in the infancy of CTC so that CTC, endoscopic, and pathologic findings might be correlated and meaningfully studied. Policies and procedures must be in place to resolve discrepant peer review findings providing the means for CTC centers to achieve quality outcomes improvement.8 For gastroenterologists to participate on a wide-scale basis in CTC interpretation, gastroenterology societies must either partner with other societies to develop appropriate peer review, quality, and safety policies and procedures, or they must initiate the process independently. Many questions remain about this process of peer review. Although this is a substantial hurdle for gastroenterology to overcome, available data confirm that gastroenterologists have the expertise to proficiently interpret CTC images, meaningfully participate in this colorectal cancer screening approach, and provide patients with colorectal cancer screening by a variety of methods within a single center. As physicians we need to identify and eliminate barriers that interfere with patient adherence to colorectal screening. Patients will benefit from a single center approach to colorectal cancer screening with a strong emphasis on providing the option of same-day optical colonoscopy should a mucosal abnormality be identified on CTC. Occasionally, because of technical or anatomic issues, optical colonoscopy may not provide complete colonic imaging. Having CTC immediately available is optimal from a patient convenience perspective, but offering the option of same-day CTC and optical colonoscopy will require a coordinated scheduling effort to ensure adequate time is preserved for endoscopy to provide definitive therapy for those with abnormal colonic findings on CTC. Same-day optical colonoscopy will require prompt interpretation of CTC data and immediate referral for optical colonoscopy. It is unlikely that patients will embrace an approach wherein optical colonoscopy follows CTC by more than 1 or 2 hours. Furthermore, studies on the quality of colonic preparation imply that if optical colonoscopy occurs greater than 4 hours after CTC, we can
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expect suboptimal colonic preparation in some cases. This event could lead to inability to localize true abnormalities identified on CTC, resulting in a false-negative optical colonoscopy. Excellent communication between the physician interpreting the CTC data and the endoscopist should and will be expected. Colorectal cancer screening centers will need to carefully follow quality parameters tracking false-negative and false-positive results of CTC and optical colonoscopy. It simply makes sense to coordinate the colorectal cancer screening effort within single centers. Centers for digestive health may effectively follow the quality of patient care while providing comprehensive colorectal cancer screening options using the modality selected by the patient and their personal physician. Gastroenterologists are well versed in the appropriate follow-up intervals for surveillance following removal of an adenomatous polyp. Although polyp growth is a fairly slow phenomenon, it is not clear whether small polyps detected at CTC may be safely followed with serial CTC for years. Gastrointestinal societies believe that patients should be fully informed about the results of their procedures and be given options regarding management. Patients will benefit from their personal physician assisting them with this process and gastroenterologists are well suited to assist with this decision making. At the time of initial consultation, information regarding the inherent risks and benefits of either optical colonoscopy or CTC may be reviewed. Patients deserve a balanced approach and the opportunity to discuss and determine the right testing approach for them. At the time of follow-up visit after either CTC or optical colonoscopy, intracolonic and extracolonic abnormalities may be discussed thoroughly. Appropriate follow-up of intracolonic abnormalities will require development of a patient health maintenance profile. Via this method, patients may be entered into a center database ensuring that they will be contacted in subsequent years when due for repeat colorectal cancer screening, be it by CTC or optical colonoscopy. Extracolonic abnormalities will require careful attention; this is best done between patients and their personal physicians. Gastroenterologists are well suited to handle any extracolonic finding identified at the time of CTC. They are also prepared to discuss simple and incidental findings with worried patients, to discuss and develop an evidence-based follow-up plan for more worrisome E3 findings, and to determine the appropriate therapeutic plan for E4 findings, such as hepatocellular carcinoma, cirrhosis, or large abdominal aortic aneurysms. Communication in medicine is difficult and, on occasion, lack of communication may result in an adverse patient outcome. Keeping the CTC experience under the direct control of the patient’s personal physician within single centers will facilitate patient care, make communication easier, and ease patient anxiety if an abnormality is identified. Centers for Digestive Health, often headed by gastroenterologists, have proliferated across the United States, with a minority of these centers also providing CTC. If CTC continues to improve and the modality is included in screening and surveillance guidelines, gastroenterologists will remain interested in this option and can discuss options with patients, perform the examinations within their center, interpret the images, proceed with endoscopy when required, and review information acquired. Medical care is fragmented by nature. Patients will benefit from their gastroenterologist being involved with every phase of their colon cancer screening experience, including the interpretation of intracolonic images obtained during CTC. REFERENCES
1. Rex DK. Clinical gastroenterologist’s perspective on training in CTcolonography. AGA Perspectives 2008. Available at: http://www.gastro.org. Accessed October, 2009.
Gastroenterologists Should Read CTC
2. Brenner DJ, Hall EJ. Computed tomography – an increasing source of radiation exposure. N Engl J Med 2007;357:2277–84. 3. Pickhardt PJ, Hanson ME, Vanness DJ, et al. Unsuspected extra-colonic findings at screening CT colonography: clinical and economic impact. Radiology 2008;249: 151–9. 4. Zalis ME, Barish MA, Choi JR, et al. CT colonography reporting and data system: a consensus proposal. Radiology 2005;236:3–9. 5. Rockey D, Barish M, Brill J, et al. CT colonography standards: standards for gastroenterologists for performing and interpreting diagnostic computed tomographic colonography. Gastroenterology 2007;133:1005–24. 6. Young PE, Ray QP, Hwang I, et al. Gastroenterologists’ interpretation of CTC: a pilot study demonstrating feasibility and similar accuracy compared with radiologist’ interpretation. Am J Gastroenterol 2009;104(12):2926–31. 7. Wang TC, Cominelli F, Fleischer DE, et al. AGA Institute Future Trends Committee report: the future of gastroenterology training programs in the United States. Gastroenterology 2008;135:1764–89. 8. 2005 ACR guidelines and technical standards. ACR position statement on quality control and improvement, safety, infection control, and patient education concerns. Page IV. Available at: http://www.acr.org/safety. Accessed October 1, 2009.
277
MD
KEYWORDS CT colonography Optical colonoscopy Colon cancer screening
Screening for colorectal neoplasms has become the standard of care in advanced medical settings worldwide. Identifying asymptomatic colorectal neoplastic lesions has been shown to reduce colorectal cancer incidence and the overall cost of medical care. Clinicians have several alternatives at their disposal as they consider screening for their respective patient population. Many different organizations have spent considerable time weighing the evidence to establish appropriate evidence-based guidelines directing clinicians how to appropriately manage screening; 2 important methods to consider are optical colonoscopy and computed tomographic colonography (CTC).1 The purpose of this article is to make the case that gastroenterologists should read CTC. By virtue of their training, there is no question that radiologists may provide this service competently. Gastroenterologists are well trained to detect and remove colonic abnormalities using optical colonoscopy. In training and practice, gastroenterologists develop considerable experience in colonic pathology and anatomic variation. Given this experience in three-dimensional intracolonic imaging, gastroenterologists are also well suited to interpret intracolonic images obtained via CTC. Furthermore, gastroenterologists work within a patient care infrastructure that provides a personal relationship with patients, and leads patients effectively and efficiently through their options for effective colorectal cancer screening. Central to the argument that gastroenterologists read CTC is the benefit of experience with threedimensional video-assisted colonic imaging and the physician-patient relationship. OPTICAL COLONOSCOPY
Clinicians use optical colonoscopy as a primary means to screen the entire colon not only for cancer but also for precancerous adenomatous lesions. Most adenomas may
Department of Internal Medicine, Mercer University School of Medicine, Memorial University Medical Center, 4700 Waters Avenue, Savannah, GA 31404, USA E-mail address: [email protected] Gastrointest Endoscopy Clin N Am 20 (2010) 271–277 doi:10.1016/j.giec.2010.02.006 1052-5157/10/$ – see front matter ª 2010 Published by Elsevier Inc.
giendo.theclinics.com
272
Carpenter
be removed at the time of optical colonoscopy. The size, location, shape, and pathologic nature of polyps may be determined during this single clinical encounter, providing the patient and clinician with valuable information to guide the future colorectal cancer screening strategy. Often, the clinician doing the endoscopic procedure has an established relationship with the patient and may provide recommendations regarding care at a subsequent clinical encounter. Established Centers of Digestive Health, worldwide, have proved to be successful in driving the colorectal cancer effort. Clearly, many patients and health care providers are comfortable with this protocol of patient care; however, optical colonoscopy does have its disadvantages. The procedure requires adequate colon cleansing to allow for complete mucosal evaluation, and many patients state that the arduous task of colonic preparation is a major drawback to the entire process. Often, colonoscopy requires moderate conscious sedation, requiring the clinician to reflect on the patient’s overall underlying medical condition: ‘‘Can my patient tolerate this degree of sedation?’’ From the patient’s perspective, moderate conscious sedation provides them with a comfortable medical procedure but also requires that the patient have access to reliable transportation from the medical setting. As a result, the patients not only have to absent themselves from their daily responsibilities, but their transporter must also take time from their routines to ensure safe passage home. This is a significant issue to consider when reviewing the overall cost of the colorectal cancer screening effort. During the insertion procedural phase and, if need be, polypectomy, perforation of the colon may occur. Although this is a relatively rare complication, it can and does occur in the care of asymptomatic patients. In addition, bleeding even after the most simple of polypectomies may occur and thus may require hospitalization or even administration of blood products. Because of the potential for colonic perforation, postpolypectomy bleeding, and other complications, adequately trained medical personnel must carefully discuss these possibilities to obtain meaningful informed consent from all patients before the procedure. There is simply no substitute for an excellent patient-physician relationship. Optical colonoscopy is not a perfect screening modality. Several tandem colonoscopy studies demonstrate that, for many reasons, adenomatous colon polyps may be missed during the procedure. Polyps may be behind folds, obscured by colonic debris, or simply not seen by the endoscopist. This issue has prompted considerable focus by gastrointestinal societies on quality parameters such as adenoma detection rate, cecal intubation rate, and colonoscopic withdrawal times. Many endoscopy centers have initiated routine documentation of these important quality measures and, collectively, we hope these developments can improve the overall colorectal cancer screening effort. Several studies demonstrate that adequate training and experience translate into improved quality; but we require additional experienced endoscopists. As the age of our patients increases and the population grows, we need to train more endoscopists with a firm grasp on the limitations of endoscopy and their role in the overall improvement of quality colorectal cancer screening. CT COLONOGRAPHY
CT colonography (CTC) is a promising colorectal screening tool, and several key factors make this method of colorectal cancer screening attractive to clinicians and patients. The procedure does not require moderate conscious sedation. Therefore, patients may provide their own transportation and return to work immediately following the examination, assuming the patient does not require further evaluation. As the colon is imaged digitally, the risk of procedurally related complications, such
Gastroenterologists Should Read CTC
as perforation and bleeding, is reduced. Improvements in CT technology over the years have resulted in continuous improvement in image quality and data acquisition time, and so in as little as 10 minutes, patients may have their procedure completed and be on the way back to society. Most importantly, CTC has resulted in increased patient awareness of the colorectal cancer screening effort. As CTC has received considerable attention in the lay press, more patients realize the value of cancer screening and may participate in the process; anything that increases overall patient awareness and acceptance of the process of cancer screening is beneficial. Despite these advantages, CT colonoscopy has its own problems. Many patients are disappointed to discover that CTC requires adequate colon preparation for optimal colonic imaging. In fact, the preparation is more complicated as contrast and fecal tagging agents are necessary to adequately differentiate stool from polyps. Trained medical personnel are required to describe the importance and nature of preparation to patients. Current screening recommendations suggest that some patients might have 5 or more CT examinations during their lifetime if CT is the primary colorectal cancer screening modality. Radiation exposure is inherent to the procedure, leading to increased concern about this degree of cumulative radiation exposure, but radiology societies have largely dismissed this issue.2 As a medical community, we do not fully understand the effects of medical radiation in a screening effort and long-term studies are needed. If a polyp is identified via CTC, most patients require optical colonoscopy for polyp removal. Some have suggested that small polyps may be followed with CT at shortened screening intervals. Although some patients may be comfortable with repeated CT examinations to follow a lesion, those in primary care know other patients will have concern about the safety of this watchand-wait approach. DISCUSSION
During CTC, extracolonic information is acquired.3 A standardized CT colonography reporting and data system (CRADS) has been developed and is useful for CTC report uniformity.4 Findings of major clinical relevance, categorized as E4 findings, arise in approximately 4% to 10% of CTC examinations. Examples of E4 findings include renal cell carcinoma, ovarian carcinoma, and an abdominal aortic aneurysm of worrisome size. Indeterminate extracolonic abnormalities are categorized as E3 findings in the CRADS system and are identified in approximately 30% of CTC examinations. Examples of E3 findings include suspicious renal and liver cysts. Findings of low clinical importance, such as simple liver and renal cysts, are placed in category E2. The frequency of E3 findings may be expected to increase, particularly if radiologists are liability averse. Furthermore, in a liability-concerned environment, some radiologists may be inclined to hedge on E2 abnormalities of low clinical importance, thereby increasing the percentage of E3 findings reported. Repeating scans to follow indeterminate findings will increase the overall cost of colorectal cancer screening. This is an important consideration when analyzing CTC from a cost efficacy perspective. Individual CT reports often suggest that E3 findings be followed at the discretion of the patient and referring physician. In the author’s clinical experience, patients tend to worry about any of these extracolonic findings. Time and patience is required to discuss even simple E2 findings with patients. In some cases, these discussions heighten the individual patient’s health care-related anxiety. An excellent doctor-patient relationship is useful in lessening this degree of anxiety and proves invaluable in many respects. For CTC to be clinically and cost effective, it is imperative that radiologists take great care in the nature of CTC extracolonic reporting and be prudent
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with E2 and E3 findings. Likewise, primary care physicians or gastroenterologists must communicate meaningfully with patients. Appropriately trained radiologists should interpret extracolonic findings identified at CT colonoscopy. Although interpretation of extracolonic CT images is thoroughly covered in gastroenterology training and practicing gastroenterologists review multiple CT images within a given work day, gastroenterologists do not have the expertise or privilege to provide an official interpretation of extracolonic CT data. In CTC centers, 1 prime goal is to provide the patient with the opportunity for a sameday optical colonoscopy. Within 20 or 30 minutes, a gastroenterologist reading CTC can provide an immediate intracolonic interpretation as the patient waits. There is no acute need for the extracolonic interpretation. CTC centers run by gastroenterologists can send CT images digitally and thus outsource the reading of extracolonic images. Gastroenterologists who provide CTC within their own center therefore have the opportunity to identify excellent radiologists who deliver high-quality interpretations. Small centers can even send CTC images to major university centers. Several high-quality radiologists have developed their own corporations to provide this service, allowing colorectal cancer screening centers to track the quality of extracolonic interpretations and change to an alternate vendor if necessary to ensure high-quality patient care. Extracolonic findings require careful evidence-based management. Colon cancer screenings centered in 1 locale provide patients with the opportunity to review and discuss colonic and extracolonic findings with 1 clinician in 1 sitting. Appropriate evidence-based management of all findings may be coordinated in this fashion. All members of the population should receive some form of testing to improve colorectal cancer screening outcomes. Unfortunately, this is not yet the case. There are many reasons for this lack of adherence, but some patients remain concerned about endoscopy. CTC presents patients with an alternative, as we have no perfect screening modality. Before making a decision, it is desirable that each patient has an understanding of the positive and negative attributes of available methods. Communication about the alternatives requires patience and time. A formal consultative visit can prove immensely beneficial. Although primary care physicians are perfectly suited to provide this service during routine visits, because of issues of time and the complexity of primary care, a thorough discussion is often not possible. Physicians who carefully follow the topic of colorectal screening realize that the data are far from static. Many primary care physicians are not fully versed about the sensitivity and specificity of optical colonoscopy and CTC in asymptomatic patients or the proper surveillance intervals for adenomas. Many patients are interested in discussing the data and options, and gastroenterologists are in a prime position to provide this expertise. With regard to the interpretation of colonic findings obtained during CTC, gastroenterologists have a wealth of experience with optical colonoscopy. Reading CTC flythrough images is intuitive to endoscopists. Standards for gastroenterologists performing and interpreting diagnostic CTC have been established and training programs organized by professional gastrointestinal organizations are effective in orienting endoscopists to this new technology.5 Although courses can be helpful for introduction, there is no substitute for hands-on experience; this can be achieved via mentored leader programs. Ideally, personal hands-on experience is obtained in centers providing CTC and optical colonoscopy services. Gastroenterologists may interpret colonic CTC images proficiently with accuracy similar to that of radiologists.6 Interpreting physicians must have adequate training and experience to ensure highly accurate readings. Experience and level of training directly correlate with accuracy. Colonoscopists with considerable experience with endoscopic imaging find CTC
Gastroenterologists Should Read CTC
colonic interpretation intuitive; however, there is a learning curve to acquire proficiency with the software used for CTC. Several vendors have created excellent CTC software and revision of these platforms continues. Gastroenterologists interested in CTC proficiency should select 1 software platform and learn it well. Development of expertise in CTC requires a substantial time commitment. It is reasonable to consider that CTC may become part of the gastrointestinal core curriculum for fellowship training.7 It is important that current gastroenterology fellows develop a basic familiarity with the indications, interpretation, and limitations of CTC. More in-depth training in CTC may become a reality where resources are available, requiring cooperation with departments of radiology. Some have suggested a new track within traditional gastroenterology training, wherein imaging becomes the focus and fellows would concentrate on technologies such as wireless capsule endoscopy and CTC. A comprehensive training curriculum would need to be established and training standards for current fellows developed. Established gastroenterologists who gravitate toward CTC and have an interest in interpretation must first demonstrate expertise and then make a personal commitment toward maintenance of proficiency. Radiologists require a meaningful physician peer review program for accreditation. Currently, there exists no infrastructure in gastroenterology societies for this quality control process. Randomly selected CTC studies would need to be reviewed on a regularly scheduled basis, requiring repeat reading of completed studies. Although members of one’s own organization might feasibly perform this task, this method of peer review might not result in meaningful critique. Therefore, review networks will need to be organized and the results must be readily available, with reviewers able to correlate the interpretation and original report with corresponding endoscopic and pathologic findings. Some recommend that a national database be developed in the infancy of CTC so that CTC, endoscopic, and pathologic findings might be correlated and meaningfully studied. Policies and procedures must be in place to resolve discrepant peer review findings providing the means for CTC centers to achieve quality outcomes improvement.8 For gastroenterologists to participate on a wide-scale basis in CTC interpretation, gastroenterology societies must either partner with other societies to develop appropriate peer review, quality, and safety policies and procedures, or they must initiate the process independently. Many questions remain about this process of peer review. Although this is a substantial hurdle for gastroenterology to overcome, available data confirm that gastroenterologists have the expertise to proficiently interpret CTC images, meaningfully participate in this colorectal cancer screening approach, and provide patients with colorectal cancer screening by a variety of methods within a single center. As physicians we need to identify and eliminate barriers that interfere with patient adherence to colorectal screening. Patients will benefit from a single center approach to colorectal cancer screening with a strong emphasis on providing the option of same-day optical colonoscopy should a mucosal abnormality be identified on CTC. Occasionally, because of technical or anatomic issues, optical colonoscopy may not provide complete colonic imaging. Having CTC immediately available is optimal from a patient convenience perspective, but offering the option of same-day CTC and optical colonoscopy will require a coordinated scheduling effort to ensure adequate time is preserved for endoscopy to provide definitive therapy for those with abnormal colonic findings on CTC. Same-day optical colonoscopy will require prompt interpretation of CTC data and immediate referral for optical colonoscopy. It is unlikely that patients will embrace an approach wherein optical colonoscopy follows CTC by more than 1 or 2 hours. Furthermore, studies on the quality of colonic preparation imply that if optical colonoscopy occurs greater than 4 hours after CTC, we can
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expect suboptimal colonic preparation in some cases. This event could lead to inability to localize true abnormalities identified on CTC, resulting in a false-negative optical colonoscopy. Excellent communication between the physician interpreting the CTC data and the endoscopist should and will be expected. Colorectal cancer screening centers will need to carefully follow quality parameters tracking false-negative and false-positive results of CTC and optical colonoscopy. It simply makes sense to coordinate the colorectal cancer screening effort within single centers. Centers for digestive health may effectively follow the quality of patient care while providing comprehensive colorectal cancer screening options using the modality selected by the patient and their personal physician. Gastroenterologists are well versed in the appropriate follow-up intervals for surveillance following removal of an adenomatous polyp. Although polyp growth is a fairly slow phenomenon, it is not clear whether small polyps detected at CTC may be safely followed with serial CTC for years. Gastrointestinal societies believe that patients should be fully informed about the results of their procedures and be given options regarding management. Patients will benefit from their personal physician assisting them with this process and gastroenterologists are well suited to assist with this decision making. At the time of initial consultation, information regarding the inherent risks and benefits of either optical colonoscopy or CTC may be reviewed. Patients deserve a balanced approach and the opportunity to discuss and determine the right testing approach for them. At the time of follow-up visit after either CTC or optical colonoscopy, intracolonic and extracolonic abnormalities may be discussed thoroughly. Appropriate follow-up of intracolonic abnormalities will require development of a patient health maintenance profile. Via this method, patients may be entered into a center database ensuring that they will be contacted in subsequent years when due for repeat colorectal cancer screening, be it by CTC or optical colonoscopy. Extracolonic abnormalities will require careful attention; this is best done between patients and their personal physicians. Gastroenterologists are well suited to handle any extracolonic finding identified at the time of CTC. They are also prepared to discuss simple and incidental findings with worried patients, to discuss and develop an evidence-based follow-up plan for more worrisome E3 findings, and to determine the appropriate therapeutic plan for E4 findings, such as hepatocellular carcinoma, cirrhosis, or large abdominal aortic aneurysms. Communication in medicine is difficult and, on occasion, lack of communication may result in an adverse patient outcome. Keeping the CTC experience under the direct control of the patient’s personal physician within single centers will facilitate patient care, make communication easier, and ease patient anxiety if an abnormality is identified. Centers for Digestive Health, often headed by gastroenterologists, have proliferated across the United States, with a minority of these centers also providing CTC. If CTC continues to improve and the modality is included in screening and surveillance guidelines, gastroenterologists will remain interested in this option and can discuss options with patients, perform the examinations within their center, interpret the images, proceed with endoscopy when required, and review information acquired. Medical care is fragmented by nature. Patients will benefit from their gastroenterologist being involved with every phase of their colon cancer screening experience, including the interpretation of intracolonic images obtained during CTC. REFERENCES
1. Rex DK. Clinical gastroenterologist’s perspective on training in CTcolonography. AGA Perspectives 2008. Available at: http://www.gastro.org. Accessed October, 2009.
Gastroenterologists Should Read CTC
2. Brenner DJ, Hall EJ. Computed tomography – an increasing source of radiation exposure. N Engl J Med 2007;357:2277–84. 3. Pickhardt PJ, Hanson ME, Vanness DJ, et al. Unsuspected extra-colonic findings at screening CT colonography: clinical and economic impact. Radiology 2008;249: 151–9. 4. Zalis ME, Barish MA, Choi JR, et al. CT colonography reporting and data system: a consensus proposal. Radiology 2005;236:3–9. 5. Rockey D, Barish M, Brill J, et al. CT colonography standards: standards for gastroenterologists for performing and interpreting diagnostic computed tomographic colonography. Gastroenterology 2007;133:1005–24. 6. Young PE, Ray QP, Hwang I, et al. Gastroenterologists’ interpretation of CTC: a pilot study demonstrating feasibility and similar accuracy compared with radiologist’ interpretation. Am J Gastroenterol 2009;104(12):2926–31. 7. Wang TC, Cominelli F, Fleischer DE, et al. AGA Institute Future Trends Committee report: the future of gastroenterology training programs in the United States. Gastroenterology 2008;135:1764–89. 8. 2005 ACR guidelines and technical standards. ACR position statement on quality control and improvement, safety, infection control, and patient education concerns. Page IV. Available at: http://www.acr.org/safety. Accessed October 1, 2009.
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