Abstract
Virtual Colonoscopy is constantly becoming more and more popular, in comparison with the traditional approach and conventional colonoscopy in particular. Despite the fact, that VC is not fully researched at the moment, most patients prefer it for increased comfort, and doctors have an opportunity to perform the extensive study of this procedure. Considering the benefits of virtual imaging, which is achieved by the means of VC, Conventional Colonoscopy gives the image of poorer quality, thus, all the benefits and demerits of both approaches should be studied and compared. Originally, ionizing radiation is used in both technologies, nevertheless, the VC is closer to computer tomography by its origin. In light of this fact, it should be stated that the original value of VC is the non-surgical principle of the procedure, while CC presupposes penetration into the patient’s rectum.
Introduction
The issues of virtual colonoscopy (VC) vs. conventional colonoscopy (CC) are often raised in the contemporary medical literature. Despite the simplicity and comfort of the former, the latter is still considered simpler, more effective and regarded as the golden standard for colon evaluation. On one hand, such evaluation is originated from the conservative approach of the medical workers who resort to conventional colonoscopy, on the other hand, the virtual colonoscopy is not fully researched at the moment, consequently, the distrust is evident and the lack of information should be filled with additional research. This paper aims to assess the technology of VC from the perspective of several factors, for filling the mentioned gap with the proper amount of arguments.
The Benefits of Virtual Imaging
The main benefit of the VC is the better tolerance of the procedure in general by the patients. While the CC procedure requires many identical preliminary preparations, it causes uncomfortable feelings in the rectum and may agitate and instigate the patient’s colonic issues. Originally, as it is stated in Jeong and Kaufman (2007, p. 560):
The Virtual Colonoscopy may resolve the reticence felt by those who would most benefit by this screening. Men over the age of fifty are at greatest risk and, often, are the least inclined to pick up the phone and schedule this procedure. But, as this procedure becomes more commonplace, that may change. The VC, though still requiring some preparation, is a much more tolerable procedure than its predecessor.
Considering this fact, there is a strong necessity to emphasize that the VC is performed using computed tomography (CT). Universal techniques may be used for the proper diagnosis and a simpler approach for achieving the required CT images. Thus, as CT scans are often used for the internal structures and organs, it should be emphasized that the presence of a tumor may be achieved by VC as easily as by the means of conventional colonoscopy.
As for the matters of injuring a patient, it is emphasized that VC is less dangerous from this point of view. Thus, as Liu Subramanian and Uitert (2007, p 491) emphasize:
There is a very small risk that inflating the colon with air could injure or perforate the bowel. This has been estimated to happen in less than one in 2,000 patients. There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk.
Consequently, most patients will agree to a less risky procedure.
The Detriments of Virtual Colonoscopy
VC and CC employ some of the same tactics to ensure proper bowel preparation. This preparation is listed as the most inconvenient step in the colonoscopy procedure, be it virtual or conventional. As reported by Aschoff et al, “‘‘Bowel cleansing’’ was given most frequently in answer to our questions, ‘‘what was the most inconvenient issue in association with CT colonography?’’ and ‘‘what was the most inconvenient issue in association with colonoscopy?’’ respectively.” The primary disadvantage of VC is that it cannot provide bioptic and therapeutic options during the examination for the same bowel preparation procedure. (Aschoff et al, 2005) If one is undergoing a colonoscopy, with the inconvenience of the bowel preparation, why would one not choose to undergo CC that can also be used to perform biopsies in the same time frame as the colonoscopy? VC also uses ionizing radiation to produce images during the CT exam. Ionizing radiation has been shown to induce leukemia and other cancers. Radiation has also been shown to induce biological defects in future offspring, thus the use of VC for patients, within the ranges of sexual reproduction, should be heavily evaluated before the CT examination.
Patient Insurance coverage
Unfortunately, since the VC is regarded to be an innovative technique, it is not listed among the traditional and accepted methods for Colon screening. Consequently, virtual colonoscopies are not covered by insurance companies, thus, patients must pay for the VC out of pocket. (Wan, Liang and Ke, 2004) On one hand, it will distract patients from resorting to VC, on the other hand, lack of insurance coverage may be regarded as a great opportunity for further evaluation of this innovative technology and method of diagnosing colon cancer. Moreover, most insurance companies cover the expenses if patients have the symptoms of colon cancer. If VC is more effective than the CC, lack of insurance coverage will not be a barrier for further research and implementation of the new technology.
Impact on Patient Safety
The risks of CC include possible bowel perforation, and bloody stools, as well as, enhancing the patient’s abdominal conditions, such as irritable bowel syndromes, constipation, etc…,. As for the radiation, it should be stated that as it is emphasized by Liu, Subramanian and Uitert (2004, p. 567): “The effective radiation dose from this procedure is about 5 mSv, which is about the same as the average person receives from background radiation in 20 months.” In the light of this fact, it should be emphasized that patient safety and measures, which are taken during the procedure do not endanger the patient’s health. Nevertheless, pregnant people, and people with increased sensitivity to x-rays should be subjected to CC, in order to avoid the increased risks.
Who should make the final decision on the issue?
The final decision on the procedure should be made by the patient, as it is up to the patient to decide whether they willingly subject themselves to the health risks. There is a small health risk associated with VC, consequently, any patient should be consulted by a radiologist and CT technologist before performing the examination. As Jeong and Kaufman (2007, p. 550) claim in one of the researches:
As with all colorectal screening methods including CC, there is no guarantee that a VC will identify all cancers and polyps. However, it is one of the most accurate colorectal cancer screening exams currently available.
In the light of this fact, it should be stated that the original value of the decision making and the procedures, which follow this decision is covered in the notion of the performed exam, and the risks, which are generally involved. Nevertheless, the patient should be explained all the alternatives, and the possibility of independent choice should be provided.
To assess the issue, what type of clinical trial or study should be required?
A successful clinical study to evaluate the necessity and outcomes of the VC involves many parameters. A substantial study must have the same patient examined by VC and CC in the same test period. This test period must be within a reasonable time, perhaps within a month of one another. The physicians, both the interpreting radiologist and the performing colonoscopist, must be ignorant of the fact that their patient is undergoing both procedures. Additionally, the interpreting radiologist must also have several hundred VC readings, this is for quality control. The patients must also adhere to the same bowel preparation procedures except the fecal tracer that must be ingested before the VC. Successful colon evaluation is dependent upon polyp size and detectability, the two studies can be cross-referenced on the same patient to see how much information is missed.
The necessity of additional research is covered in the notion that there are restrictions found while practicing virtual colonoscopy. The fact is some of these restrictions have not been confirmed, and all the capabilities of this procedure have not been studied in full measure. Thus, as Jeong and Kaufman (2007, p. 555) state:
A person who is very large may not fit into the opening of a conventional CT scanner or may be over the weight limit for the moving table. CT colonography is strictly a diagnostic procedure. If any significant polyps are found, they will have to be removed by conventional colonoscopy. Many insurance companies do not cover CT colonography as a screening test for colonic polyps, but they may cover the cost of a patient who has symptoms related to the colon.
Consequently, further research is needed for defining the capabilities and restrictions associated with the process of virtual colonoscopy.
Conclusion
Finally the issues associated with virtual colonoscopy generally require additional research, as well as, increased public awareness. The general public must realize that a VC will not assess colon polyps by bioptic means, and that the VC is for screening only. Nevertheless, in comparison with conventional colonoscopy, virtual colonoscopy is safer and simpler for colon cancer screening. One must remember that the success of the VC in diagnosing colon abnormalities is heavily dependent upon proper radiologist and CT technologist training. The CT technologist must follow accepted protocols for each CT procedure and the radiologist must have hundreds of practice readings before interpreting the patient’s VC images.
References
Aschoff, A., Brambs, H., Ehmann, J., & Junchems, M. (2005). A Retrospective Evaluation of Patient Acceptance of Computed Tomography Colonography (“Virtual Colonoscopy”) in Comparison with Conventional Colonoscopy in an Average Risk Screening Population. Acta Radiologica, 46(7), 664-670.
Chen, D., Wax, M.R., Li, L., Liang, Z., Li, B., Kaufman, A.E., (2002) “A novel approach to extract colon lumen from CT images for virtual colonoscopy” MedImg(19), No. 12, pp. 1220-1226.
Jeong, S.J., Kaufman, A.E. (2007) “Interactive wireless virtual colonoscopy” VC(23), pp. 545-557.
Liu, J.F., Subramanian, K., Yoo, T., van Uitert, R. (2004) “A stable optic-flow based method for tracking colonoscopy images” Tensor No. 1. Vol. 8
Wan, M., Liang, Z.R., Ke, Q., Hong, L.C., Bitter, I., Kaufman, A. (2004) “Automatic centerline extraction for virtual colonoscopy” MedImg21, No. 12, pp. 1450-1460.