Virtual colonoscopy

Virtual Colonoscopy in Colorectal Cancer Screening

Colorectal cancer is the third most commonly diagnosed tumor in both males and females in the United States. Current modalities for colorectal cancer screening include fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Virtual colonoscopy is a promising new method for assessing the entire colon. Vining and Gelfand first described this technique in 1994. Since then, virtual colonoscopy has been shown to be extremely safe and well tolerated by patients. Indications for virtual colonoscopy include screening for polyps, incomplete or failed colonoscopy, and preoperative assessment of the colon proximal to an occlusive cancer or even redundant fixed or stenotic colon that cannot be endoscopically traversed. Virtual colonoscopy may dramatically increase patient participation in screening programs, leading to early diagnosis of colorectal cancer. Although virtual colonoscopy seems a potentially attractive screening method for colorectal cancer, the cost-effectiveness of this method is yet to be determined.

Implications of Aging in Surgical Oncology

Global growth of the elderly population is requiring health care providers to cater to an expanding elderly cancer subpopulation. Surgeons are called upon to provide optimal cancer management for this heterogeneous group in par with care provided for younger patients, an ethical dilemma that is compounded by an ill-understood tumor biology. Delivery of suboptimal surgical cancer treatment due to ageist attitudes and personal beliefs is no longer acceptable. Cancer surgeons have to offer optimal surgery in consideration of individualized operative risk. The need for a tool to assess operative risk and predict postoperative outcome is obvious. This article wishes to raise awareness among surgeons about epidemiology, physiologic changes, performance status and comorbidities, and patterns of care and ways to improve them. We visit existing tools to assess operative risk, reveal interim results from the Preoperative Assessment of Cancer in Elderly (PACE) study, and discuss the future of oncogeriatrics.

Spasmolysis at CT colonography: butyl scopolamine versus glucagon

PURPOSE

To retrospectively determine if the use of butyl scopolamine or glucagon in the supine patient improves colonic distention and reduces the number of collapsed intestinal segments at computed tomographic (CT) colonography.

MATERIALS AND METHODS

This study had institutional review board approval; subject informed consent was not required. CT colonography was performed without the administration of an intravenous spasmolytic in 80 asymptomatic subjects (group 1; 45 women, 35 men; age range, 48-77 years; mean, 61.9 years). These subjects were matched with two groups of 80 subjects who were similar in age but were premedicated with glucagon (group 2; 41 women, 39 men; age range, 43-76 years; mean, 63.1 years) or butyl scopolamine (group 3; 43 women, 37 men; age range, 34-77 years; mean, 63.4 years). All 240 subjects were examined in the supine position with multisection CT and a section thickness of 1 mm after intravenous contrast agent administration and rectal carbon dioxide insufflation. The colon was divided into seven segments, and the colon length, total volume, radial distensibility, and number of non-distended segments were calculated for each subject and compared among the three groups. Statistical analysis was performed with analysis of variance and chi2 testing.

RESULTS

Mean bowel length was not significantly different among the groups. Mean colon volumes and radial distensibilities, respectively, were 1.84 L and 3.69 cm in group 1, 2.14 L and 3.98 cm in group 2, and 2.35 L and 4.23 cm in group 3; differences in colon volume and radial distensibility were significant only between group 1 and group 3 (P < .001). At CT colonography, 29 segments in 20 group 1 subjects were collapsed, 23 segments in 12 group 2 subjects were collapsed, and 11 segments in six group 3 subjects were collapsed (P = .016).

CONCLUSION

Premedication with butyl scopolamine or, less effectively, glucagon improves colonic distention in the supine subject.

The surgical management of elderly cancer patients

Although cancer in the elderly is extremely common, few health professionals in oncology are familiar with caring for series of oncogeriatric patients. Surgery is at present the first choice, but is frequently delivered suboptimally: under-treatment is justified by concerns about unsustainable toxicity, whilst over-treatment is explained by the lack of knowledge in optimising preoperative risk assessment. This article summarises the point of view of the Surgical Task Force @ SIOG (International Society for Geriatric Oncology), pointing out differences from, and similarities to, the younger cohorts of cancer patients, and highlighting the latest updates and trends specifically related to senior cancer patients.

Options for screening for colorectal cancer

Unlike other types of cancer, there are several options for screening for colorectal cancer (CRC). The most extensively examined method, faecal occult blood testing (FOBT), has been shown, in three large randomized trials, to reduce mortality from CRC by up to 20% if offered biennally and possibly more if offered every year. Recently published data from the US trial suggest that CRC incidence rates are also reduced by up to 20%, but only after 18 years. In this study, the number of positive slides was associated with the positive predictive value both for CRC and adenomas larger than 1 cm, suggesting that the reduction in CRC incidence was caused by the identification and removal of large adenomas. In this respect, this study supports the concept that removing adenomas prevents CRC. More efficient methods of detecting adenomas include the use of colonoscopy or flexible sigmoidoscopy (FS). Considerable evidence exists from case-control and uncontrolled cohort studies to suggest that endoscopic screening by sigmoidoscopy reduces incidence of distal colorectal cancer. However, in the absence of evidence from a randomized trial, several countries have been reluctant to introduce endoscopic screening. Three trialsare currently in progress (in the UK, Italy and the US) to address this issue. Two of these trials are examining the hypothesis that a single FS screen at around age 55-64 might be a cost-effective and acceptable method for reducing CRC incidence rates. Recruitment and screening are now complete in both studies and the first analysis of results on incidence rates is expected in 2004. Colonoscopy screening at 10-year intervals has recently been endorsed in the US on the basis that the reductions in incidence observed with distal CRC screening can be extrapolated to the proximal colon. However, data are lacking and a pilot study for a trial of the acceptability and efficacy of colonoscopy screening is in progress in the US. It has also been suggested that FOBT testing should be used to detect proximal CRC missed by sigmoidoscopy screening, but the small amount of published data suggest that supplementing FS with FOBT offers very little advantage over FS alone. Other forms of CRC screening are under investigation and represent exciting options for the future. Extraction of DNA from stool is now feasible and a number of research groups have shown high sensitivity for CRC using a panel of DNA markers including mutations in k-ras, APC, p53 and BAT26. Data so far indicate that, with the exception of k-ras, these markers are highly specific and therefore represent a significant improvement over FOBT. Whether these tests will replace or supplement existing methods of screening has yet to be determined. It has been suggested that BAT26, which is a marker of microsatellite instability, a feature of proximal sporadic CRC, might be a useful adjunct to sigmoidoscopy screening. Others have suggested that a test for occult blood should be included with the DNA markers to further increase sensitivity. It is not yet known how sensitive these markers are for adenomas--it is only by detecting adenomas that CRC incidence rates can be reduced. A final exciting new option for screening is virtual colonoscopy (VC), which by screening out people without neoplasia allows colonoscopy to be reserved for patients requiring a therapeutic intervention. The sensitivity of VC for large adenomas and CRC appears to be high, although results vary by centre and there is a steep learning curve. Sensitivity for small adenomas is low, but perhaps it is less essential to find such lesions. Some groups have suggested that virtual colonoscopy might be a useful option for investigating patients who test positive with stool-based screening tests. Whichever CRC screening method is finally chosen (and there is no reason why several methods should not ultimately be available), high quality endoscopy resources will always be required to investigate and treat neoplastic lesions detected.

Virtual surgery in a (tele-)radiology framework

This paper presents telemedicine as an extension of a teleradiology framework through tools for virtual surgery. To classify the described methods and applications, the research field of virtual reality (VR) is broadly reviewed. Differences with respect to technical equipment, methodological requirements and areas of application are pointed out. Desktop VR, augmented reality, and virtual reality are differentiated and discussed in some typical contexts of diagnostic support, surgical planning, therapeutic procedures, simulation and training. Visualization techniques are compared as a prerequisite for virtual reality and assigned to distinct levels of immersion. The advantage of a hybrid visualization kernel is emphasized with respect to the desktop VR applications that are subsequently shown. Moreover, software design aspects are considered by outlining functional openness in the architecture of the host system. Here, a teleradiology workstation was extended by dedicated tools for surgical planning through a plug-in mechanism. Examples of recent areas of application are introduced such as liver tumor resection planning, diagnostic support in heart surgery, and craniofacial surgery planning. In the future, surgical planning systems will become more important. They will benefit from improvements in image acquisition and communication, new image processing approaches, and techniques for data presentation. This will facilitate preoperative planning and intraoperative applications.