Extracolonic findings at virtual colonoscopy: implications for screening programs

Screening for Colorectal Cancer

Colorectal cancer (CRC) is the second leading cause of cancer death. Screening has been proven to reduce both cancer incidence and cancer-related mortality. Various screening tests are available, each with their own advantages and disadvantages and varying levels of evidence to support their use. Clinicians should offer CRC screening to average-risk persons aged 50 to 75 years; starting screening at age 45 years remains controversial. Screening may be beneficial in select persons aged 76 to 85 years, based on their overall health and screening history. Offering a choice of screening tests or sequentially offering an alternate test for those who do not complete screening can significantly increase participation.

The bowel and beyond: extracolonic findings from CT colonography

CT colonography has emerged as the investigation of choice for suspected colorectal cancer in patients when a colonoscopy in incomplete, is deemed high risk or is declined because of patient preference. Unlike a traditional colonoscopy, it frequently reveals extracolonic as well as colonic findings. Our study aimed to determine the prevalence, characteristics and potential significance of extracolonic findings on CT colonography within our own institution. A retrospective review was performed of 502 patients who underwent CT colonography in our institution between January 1, 2010 and January 4, 2015. Of 502 patients, 60.63% had at least one extracolonic finding. This was close to other similar-sized studies (Kumar et al. Radiology 236(2):519-526, 2005). However, our rate of E4 findings was significantly higher than that reported in larger studies at 5.3%(Pooler et al. AJR 206:313-318, 2016). The difference may be explained by our combination of symptomatic/screening patients or by the age and gender distribution of our population. Our study lends support to the hypothesis that CT colonography may be particularly useful in identifying clinically significant extracolonic findings in symptomatic patients. CT colonography may allow early identification of extracolonic malignancies and life-threatening conditions such as an abdominal aortic aneurysm at a preclinical stage when they are amenable to medical or surgical intervention. However, extracolonic findings may also result in unnecessary investigations for subsequently benign findings.

Extracolonic findings and radiation at CT colonography: what the referring provider needs to know

A better understanding of the risks and benefits of extracolonic findings and radiation dose will aid in the safe and proper implementation of CT colonography in clinical practice. The majority of extracolonic findings in screening patients are benign and can be ignored by referring physicians. Radiologists also need to be responsible in reporting extracolonic findings. Referring providers must be knowledgeable about the theoretic risks and controversies regarding the use of ionizing radiation. Screening CT colonography imparts a low-level of radiation to patients that is equivalent or less than annual background dose.

Lumbar Transforaminal Epidural Steroid Injections: Incidental Extraspinal Findings on Planning Imaging

OBJECTIVE

Planning imaging performed during CT-guided procedures may occasionally contain important incidental findings. The purpose of this study was to identify and characterize by clinical relevance the extraspinal findings detected on planning imaging for CT-guided lumbar transforaminal epidural steroid injections (TFESIs).

MATERIALS AND METHODS

Four radiologists retrospectively evaluated the planning scout views and CT studies for 488 consecutive CT-guided lumbar TFESIs performed in 400 patients over a 1-year period. Incidental extraspinal findings were identified and used to characterize patients by the need for follow-up using the CT Colonography Reporting and Data System (C-RADS), a classification scheme originally developed to characterize incidental findings on CT colonography. Patients with C-RADS E4 findings have potentially important findings that should be communicated to the referring physician; patients with C-RADS E3 findings have findings that are likely unimportant, but workup may be indicated. All previously unknown C-RADS E3 and E4 findings discovered in the course of this research were reported to referring physicians for appropriate patient follow-up.

RESULTS

Ten of 400 (2.5%) patients were classified as C-RADS E4; the most common C-RADS E4 finding was vascular aneurysm or stenosis (4/400, 1.0%). Thirteen of 400 (3.3%) patients were classified as C-RADS E3; the most common C-RADS E3 finding was hepatomegaly (4/400, 1.0%). Of 22 patients with C-RADS E3 and E4 findings unknown to clinicians, the finding for only one (4.5%) was communicated to clinicians at the time of the procedure.

CONCLUSION

Clinically important incidental extraspinal findings were identified in 5.8% of patients on the planning imaging performed for CT-guided lumbar TFESIs. Communication of clinically important findings was poor (4.5%).

Is intravenous contrast necessary for detection of clinically significant extracolonic findings in patients undergoing CT colonography?

OBJECTIVE

To determine whether intravenous contrast (IVC) is necessary for detection of extracolonic findings (ECFs) in patients undergoing CT colonography (CTC).

METHODS

We performed a retrospective review of CT findings in 179 cases of CTC studies performed over 18 months where both pre-contrast (NECT) and post-contrast (CECT) scans were performed in the prone and supine positions, respectively, in the same patients. All ECFs were recorded on a per patient basis and graded according to the colonography reporting and data system classification.

RESULTS

There was no significant change in E grade for the cohort (p = 0.171) between the NECT and CECT scans. On the CECT scans, additional findings were detected in 49.1% of patients. Overall, there were 27/179 (15.1%) patients graded E3 and 18/179 (10.1%) patients graded E4 on the CECT study. Compared with the NECT study, there was a decrease of 12.9% of patients graded E3 and no change in the number of patients graded E4.

CONCLUSION

With IVC administration, additional ECFs are detected in nearly half of all patients. However, there was no increase in the number of patients with clinically significant lesions. The risk-benefit ratio of routine IVC administration for CTC in symptomatic patients thus requires further evaluation.

ADVANCES IN KNOWLEDGE

This study reviews the utility of IVC in CTC and is thus relevant to current clinical practice at many institutions.

Colorectal cancer: screening and surveillance for high-risk individuals

Colorectal cancer is very common and is closely related to patient age. After age, the second most common risk factor is family history of colon cancer. In fact, it is one of the most hereditable cancers. Colon cancer is preventable and screening has demonstrated efficacy in the reduction of both the incidence and the mortality from colorectal cancer. Several screening techniques are currently available, including endoscopy and nonendoscopic-based techniques. Screening strategies vary according to the individual risk of colon cancer. This paper will focus on the screening recommendations for patients with high-risk colon cancer.

Extracolonic findings (ECF) on CT colonography (CTC) in patients presenting with colorectal symptoms

BACKGROUND

Computed tomographic colonography (CTC) is now an established method for imaging the colon and rectum in the screening and symptomatic setting. Additional benefit of CTC is the ability to assess for extracolonic findings especially in patients presenting with colorectal symptoms.

PURPOSE

To determine prevalence of extracolonic findings (ECF) in symptomatic patients undergoing CTC and determine accuracy of CTC for exclusion of significant abdominal disease and extracolonic malignancy (ECM).

MATERIAL AND METHODS

A total of 1359 unenhanced prone and postcontrast supine CTC studies were performed between March 2002 and December 2007. ECF were retrospectively classified according to C-RADS criteria into E1 to E4 findings. For ECM, a gold standard of clinical and/or radiological follow-up supplemented with data from the regional cancer registry with a median follow-up of 42 months was created. Sensitivity and negative predictive values for ECM was calculated.

RESULTS

Following exclusions, 1177 CTCs were analyzed. Of 1423 extracolonic findings reported, 328/1423 (23%) E3 and 100/1423 (7%) E4 (including six eventual FP studies) findings were identified. Thirty-two ECMs were confirmed following further investigations. Seven further small ECMs were detected during the entire follow-up, of which two were potentially visible in retrospect (false-negative studies). Additional tests were generated from 55/1177 (4.7%) studies. Sensitivity and negative predictive value for ECM was 94.1% (95% CI 78.9-98.9%) and 99.8% (95% CI 99.3-99.9%), respectively.

CONCLUSION

One in 37 patients were found to have an ECM. Two potentially detectable cancers were missed. Only a small proportion of patients underwent additional work-up.

The time has arrived for national reimbursement of screening CT colonography

OBJECTIVE

CT colonography (CTC) has been fully validated as an accurate screening test for colorectal carcinoma and is being disseminated globally. There is an abundance of new literature addressing the prior concerns of the U.S. Preventive Services Task Force and the Centers for Medicare & Medicaid Services. Specific areas related to radiation dose, extracolonic findings, and generalizability of CTC to senior patients are discussed.

CONCLUSION

The time has arrived for national reimbursement of CTC in the United States.

Suspected extracolonic neoplasms detected on CT colonography: literature review and possible outcomes

RATIONALE AND OBJECTIVES

This study summarizes the literature on the detection of cancer among indeterminate extracolonic findings on computed tomographic (CT) colonography in five targeted organs.

MATERIALS AND METHODS

We searched PubMed for English-language literature published between January 1, 1994, and December 31, 2010. We describe extracolonic findings in the kidney, lung, liver, pancreas, and ovary suspect for malignancy as they are associated with high mortality. For each organ, we calculated the median prevalence, positive predictive value (PPV), and false positive rate of malignancy and a pooled false-positive rate across studies.

RESULTS

Of 91 publications initially identified, 24 were eligible for review. Indeterminate renal masses on CT colonography had 20.5% median PPV and low pooled false positive rate of 1.3% (95% confidence interval 0.6-2.0). In contrast, indeterminate masses of the lung, liver, pancreas, and ovary had low PPV (median values ranged from 0% to 3.8%). Indeterminate masses of the ovary resulted in the highest pooled false-positive rate of 2.2%. Results were similar in studies of both screening and nonscreening populations. We estimated the probability of false positive results through the detection of significant extracolonic findings as 46 per 1000 for men and 68 per 1000 for women.

CONCLUSIONS

Indeterminate renal masses newly detected on CT colonography have an estimated one in five chance of malignancy and therefore warrant further follow-up to provide a definitive diagnosis. Conversely, indeterminate masses of the lung, liver, pancreas, and ovary are associated with high false positive rates and merit more conservative clinical follow-up.

Comparative economic evaluation of data from the ACRIN National CT Colonography Trial with three cancer intervention and surveillance modeling network microsimulations

PURPOSE

To estimate the cost-effectiveness of computed tomographic (CT) colonography for colorectal cancer (CRC) screening in average-risk asymptomatic subjects in the United States aged 50 years.

MATERIALS AND METHODS

Enrollees in the American College of Radiology Imaging Network National CT Colonography Trial provided informed consent, and approval was obtained from the institutional review board at each site. CT colonography performance estimates from the trial were incorporated into three Cancer Intervention and Surveillance Modeling Network CRC microsimulations. Simulated survival and lifetime costs for screening 50-year-old subjects in the United States with CT colonography every 5 or 10 years were compared with those for guideline-concordant screening with colonoscopy, flexible sigmoidoscopy plus either sensitive unrehydrated fecal occult blood testing (FOBT) or fecal immunochemical testing (FIT), and no screening. Perfect and reduced screening adherence scenarios were considered. Incremental cost-effectiveness and net health benefits were estimated from the U.S. health care sector perspective, assuming a 3% discount rate.

RESULTS

CT colonography at 5- and 10-year screening intervals was more costly and less effective than FOBT plus flexible sigmoidoscopy in all three models in both 100% and 50% adherence scenarios. Colonoscopy also was more costly and less effective than FOBT plus flexible sigmoidoscopy, except in the CRC-SPIN model assuming 100% adherence (incremental cost-effectiveness ratio: $26,300 per life-year gained). CT colonography at 5- and 10-year screening intervals and colonoscopy were net beneficial compared with no screening in all model scenarios. The 5-year screening interval was net beneficial over the 10-year interval except in the MISCAN model when assuming 100% adherence and willingness to pay $50,000 per life-year gained.

CONCLUSION

All three models predict CT colonography to be more costly and less effective than non-CT colonographic screening but net beneficial compared with no screening given model assumptions.

Management of concomitant cancer and abdominal aortic aneurysm

Background. The coexistence of neoplasm and abdominal aortic aneurysm (AAA) presents a real management challenge. This paper reviews the literature on the prevalence, diagnosis, and management dilemmas of concurrent visceral malignancy and abdominal aortic aneurysm. Method. The MEDLINE and HIGHWIRE databases (1966-present) were searched. Papers detailing relevant data were assessed for quality and validity. All case series, review articles, and references of such articles were searched for additional relevant papers. Results. Current challenges in decision making, the effect of major body-cavity surgery on an untreated aneurysm, the effects of major vascular surgery on the treatment of malignancy, the use of EVAR (endovascular aortic aneurysm repair) as a fairly low-risk procedure and its role in the management of malignancy, and the effect of other challenging issues such as the use of adjuvant therapy, and patients informed decision-making were reviewed and discussed. Conclusion. In synchronous malignancy and abdominal aortic aneurysm, the most life-threatening lesion should be addressed first. Endovascular aneurysm repair where possible, followed by malignancy resection, is becoming the preferred initial treatment choice in most centres.

Colorectal cancer screening comparing no screening, immunochemical and guaiac fecal occult blood tests: a cost-effectiveness analysis

Comparability of cost-effectiveness of colorectal cancer (CRC) screening strategies is limited if heterogeneous study data are combined. We analyzed prospective empirical data from a randomized-controlled trial to compare cost-effectiveness of screening with either one round of immunochemical fecal occult blood testing (I-FOBT; OC-Sensor®), one round of guaiac FOBT (G-FOBT; Hemoccult-II®) or no screening in Dutch aged 50 to 75 years, completed with cancer registry and literature data, from a third-party payer perspective in a Markov model with first- and second-order Monte Carlo simulation. Costs were measured in Euros (€), effects in life-years gained, and both were discounted with 3%. Uncertainty surrounding important parameters was analyzed. I-FOBT dominated the alternatives: after one round of I-FOBT screening, a hypothetical person would on average gain 0.003 life-years and save the health care system €27 compared with G-FOBT and 0.003 life years and €72 compared with no screening. Overall, in 4,460,265 Dutch aged 50-75 years, after one round I-FOBT screening, 13,400 life-years and €320 million would have been saved compared with no screening. I-FOBT also dominated in sensitivity analyses, varying uncertainty surrounding important effect and cost parameters. CRC screening with I-FOBT dominated G-FOBT and no screening with or without accounting for uncertainty.

Incidental findings in imaging research: evaluating incidence, benefit, and burden

BACKGROUND

Little information exists concerning the frequency and medical significance of incidental findings (IFs) in imaging research.

METHODS

Medical records of research participants undergoing a research imaging examination interpreted by a radiologist during January through March 2004 were reviewed, with 3-year clinical follow-up. An expert panel reviewed all IFs generating clinical action to determine medical benefit/burden on the basis of predefined criteria. The frequency of IFs that generated further clinical action was estimated by modality, body part, age, and sex, along with net medical benefit or burden.

RESULTS

Of 1426 research imaging examinations, 567 (39.8%) had at least 1 IF (1055 total). Risk of an IF increased significantly by age (odds ratio [OR], 1.5; 95% confidence interval, 1.4-1.7 per decade increase). Abdominopelvic computed tomography generated more IFs than other examinations (OR, 18.9 vs ultrasonography; 9.2% with subsequent clinical action), with computed tomography of the thorax and magnetic resonance imaging of the head next (OR, 11.9 and 5.9; 2.8% and 2.2% with action, respectively). Of the 567 examinations with an IF, 35 (6.2%) generated clinical action, resulting in clear medical benefit in 1.1% (6 of 567) and clear medical burden in 0.5% (3 of 567). Medical benefit/burden was usually unclear (26 of 567 [4.6%]).

CONCLUSIONS

Frequency of IFs in imaging research examinations varies significantly by imaging modality, body region, and age. Research imaging studies at high risk for generating IFs can be identified. Routine evaluation of research images by radiologists may result in identification of IFs in a high number of cases and subsequent clinical action to address them in a small but significant minority. Such clinical action can result in medical benefit to a small number of patients.

Extracolonic findings on CT colonography increases yield of colorectal cancer screening

OBJECTIVE

The purpose of this study is to evaluate the impact of extracolonic findings when screening is undertaken by CT colonography (CTC).

MATERIALS AND METHODS

We performed a retrospective cohort study of patients completing a screening CTC from August 2003 to June 2006 at Walter Reed Army Medical Center. Extracolonic findings were categorized using a CTC reporting and data system that classifies findings as highly significant, likely significant, and insignificant. All final diagnoses, surgeries, malignancies, and costs of diagnostic radiology procedures were calculated for each category.

RESULTS

Of 2,277 patients (mean +/- SD age, 59 +/- 11 years; 60% white; 56% male) undergoing CTC, extracolonic findings were identified in 1,037 (46%) patients, with 787 (34.5%) insignificant and 240 (11.0%) significant findings. Evaluation of significant findings generated 280 radiology procedures and 19 surgeries over a mean follow-up time of 19 +/- 10 months. The total cost of the radiology studies was $113,179; the studies added approximately $50 extra per patient. Seven high-risk lesions were identified (six extracolonic malignancies and one large aortic aneurysm) in patients with significant findings. CTC also identified six intracolonic malignancies and three adenomas with high-grade dysplasia. When considering extracolonic findings, CTC increased the odds of identifying high-risk lesions by 78% (nine intracolonic lesions vs 16 intracolonic plus extracolonic lesions; p = 0.0156). Of the 16 intracolonic and extracolonic high-risk lesions, 11 (69%) underwent curative resection, and 5 of 11 (44.4%) were extracolonic.

CONCLUSION

CTC increased the odds of identifying high-risk lesions by 78%. CTC should be considered as an alternative to optical colonoscopy for colorectal cancer screening or as a onetime procedure to identify significant treatable intracolonic and extracolonic lesions.

Colorectal cancer screening: The role of CT colonography

Computed tomography colonography (CTC) in colorectal cancer (CRC) screening has two roles: one present and the other potential. The present role is, without any further discussion, the integration into established screening programs as a replacement for barium enema in the case of incomplete colonoscopy. The potential role is the use of CTC as a first-line screening method together with Fecal Occult Blood Test, sigmoidoscopy and colonoscopy. However, despite the fact that CTC has been officially endorsed for CRC screening of average-risk individuals by different scientific societies including the American Cancer Society, the American College of Radiology, and the US Multisociety Task Force on Colorectal Cancer, other entities, such as the US Preventive Services Task Force, have considered the evidence insufficient to justify its use as a mass screening method. Medicare has also recently denied reimbursement for CTC as a screening test. Nevertheless, multiple advantages exist for using CTC as a CRC screening test: high accuracy, full evaluation of the colon in virtually all patients, non-invasiveness, safety, patient comfort, detection of extracolonic findings and cost-effectiveness. The main potential drawback of a CTC screening is the exposure to ionizing radiation. However, this is not a major issue, since low-dose protocols are now routinely implemented, delivering a dose comparable or slightly superior to the annual radiation exposure of any individual. Indirect evidence exists that such a radiation exposure does not induce additional cancers.

Prevalence of extravascular collateral findings during 64-slice CT angiography of the abdominal aorta and lower limbs

PURPOSE

The aim of this study was to assess the prevalence of extravascular collateral findings during 64-slice CT angiography of the abdominal aorta (AA-CTA) and lower limbs (LL-CTA).

MATERIALS AND METHODS

The images of 536 AA-CTA and LL-CTA examinations performed for suspected aortic and peripheral vascular disease in 500 patients were retrospectively reviewed. Two radiologists evaluated the 5-mm axial images independently using appropriate window settings for the area under investigation. Collateral findings were divided according to their clinical significance into significant, nonsignificant and meriting further investigation.

RESULTS

No collateral findings were identified in 97/500 patients (19.4%). In the remaining patients, 821 collateral findings were detected, of which 43 (5.24%) were classified as significant, 135 (16.44%) as meriting further investigation and 643 (78.32%) as nonsignificant. The findings indicative of the presence of a malignant lesion totalled 36 (4.5%).

CONCLUSIONS

AA-CTA and LL-CTA demonstrate a nonnegligible prevalence of collateral findings, many of them major. It therefore appears that the evaluation should focus not only on the image reconstructions to identify vascular disease, but also on the native axial images to detect incidental findings.

Extracolonic findings at CT colonography

Computed tomographic colonography (CTC) is a validated tool for the evaluation of the colon for polyps and cancer. The technique employed for CTC includes a low-dose CT scan of the abdomen and pelvis that is typically performed without the administration of intravenous contrast. Using this technique it is possible to discover findings outside of the colon. By far, most extracolonic findings are determined to be clinically inconsequential on CTC and most patients are not recommended for further testing. However, some findings may result in additional diagnostic evaluation or intervention, which can lead to patient anxiety and increased morbidity and health care costs. Alternatively, some findings can lead to the earlier diagnosis of a clinically significant lesion, which could result in decreased patient morbidity and mortality as well as overall savings in downstream health care costs. The controversies of detecting and evaluating these incidental extracolonic findings on CTC are discussed.

Gastroenterologists' interpretation of CTC: a pilot study demonstrating feasibility and similar accuracy compared with radiologists' interpretation

OBJECTIVES

Computed tomography colonography (CTC) is an emerging colon cancer screening modality that has the potential to increase adherence to current screening recommendations. Traditionally, the interpretation of CTC has been limited to radiologists. As the technology of CTC has developed, three-dimensional endoluminal fly-through images have largely replaced two-dimensional CT images as the primary reading modality. Such a display is a realistic corollary to the endoscopic view obtained during colonoscopy. Our study sought to determine whether gastroenterologists could interpret the colonic display of CTC with an accuracy similar to that of trained radiologists.

METHODS

Three board-certified gastroenterologists and four gastroenterology fellows in various stages of training interpreted a mean of 45 CTCs (range: 30-50) in which colonoscopy had also been performed. Before reading any cases, each reader underwent CTC interpretation training with an experienced CTC radiologist. After interpreting each CTC, the gastroenterologist had access to both the original radiology interpretation of the CTC and the corresponding colonoscopy results. Outcomes included accuracy of the gastroenterologists' interpretation, time required for CTC interpretation, evidence of learning, and the level of diagnostic agreement between gastroenterologists and radiologists.

RESULTS

Gastroenterologist readers identified polyps >or=6 mm on CTC with a mean sensitivity and specificity of 83.5% (67-100%) and 78.8% (69-100%), respectively. Corresponding values for polyps >or=8 mm were 83.8% (68-100%) and 74% (30-93%), respectively, and those for polyps >or=10 mm were 87.8% (67-100%) and 85.2% (60-94%), respectively. Overall, 83% (5 of 6) of gastroenterologists achieved kappa scores >or=0.60, suggesting good agreement with radiologists; 66% achieved kappa>or=0.75. There was a direct relationship between diagnostic accuracy and level of gastroenterology training, with third-year fellows being nearly as accurate as the attendings. The average gastroenterologist CTC reading time was 18.4 min (range: 11.2-25.6).

CONCLUSIONS

The gastroenterologists in this study were able to read CTCs with an accuracy that approaches that of radiologists. The level of training affected the accuracy of CTC interpretation by the gastroenterologist. Average gastroenterologist CTC interpretation times in this study were similar to recommended colonoscopy times. Further studies are warranted to determine whether gastroenterologists are able to interpret CTCs independently in clinical practice.

Extracolonic findings of computed tomographic colonography in Koreans

AIM: To determine the frequency and characteristics of extracolonic lesions detected using computed tomographic (CT) colonography.

METHODS: The significance of extracolonic lesions was classified as high, intermediate, or low. Medical records were reviewed to establish whether further investigations were carried out pertaining to the extracolonic lesions that were detected by CT colonography.

RESULTS: A total of 920 cases from 7 university hospitals were included, and 692 extracolonic findings were found in 532 (57.8%) patients. Of 692 extracolonic findings, 60 lesions (8.7%) were highly significant, 250 (36.1%) were of intermediate significance, and 382 (55.2%) were of low significance. CT colonography revealed fewer extracolonic findings in subjects who were without symptoms (P < 0.001), younger (P < 0.001), or who underwent CT colonography with no contrast enhancement (P = 0.005). CT colonography with contrast enhancement showed higher cost-effectiveness in detecting highly significant extracolonic lesions in older subjects and in subjects with symptoms.

CONCLUSION: Most of the extracolonic findings detected using CT colonography were of less significant lesions. The role of CT colonography would be optimized if this procedure was performed with contrast enhancement in symptomatic older subjects.

Incidental extracolonic findings on CT colonography: the impending deluge and its implications

The probable future widespread adoption of computed tomographic colonography (CTC) will lead to the detection of numerous incidental extracolonic findings (ECFs). Defining, characterizing, and making diagnostic and management recommendations for such ECFs are likely to be inconsistent and, averaged over the patient population, may be more costly than CTC itself. Several reports that suggested a modest cost for evaluating ECFs did not include all of the downstream costs of diagnosis and treatment, while studies that more closely tracked costs arrived at figures up to 5 times as high. The ECF aspect of CTC is analogous to total-body screening, which has been widely criticized, and the cost-effectiveness of evaluating and managing ECFs is unproven and controversial, which also has implications for managing incidental findings from other applications for abdominal and pelvic computed tomography. The author reviews studies that have assessed the frequency, costs, and effects of ECFs. Establishing national or local criteria for detecting ECFs and providing recommendations for referring clinicians may be an important step toward achieving the most effective patient care for ECFs, which are the inevitable consequence of performing CTC.

Extracolonic findings at virtual colonoscopy: an important consideration in asymptomatic colorectal cancer screening

BACKGROUND

Virtual colonoscopy has been evaluated for use as a colorectal cancer screening tool, and in prior studies, it has been estimated that the evaluation of extra-colonic findings adds $28-$34 per patient studied.

METHODS

As an ancillary study to a prospective cohort study comparing virtual colonoscopy to conventional colonoscopy for colorectal cancer detection, the investigators retrospectively determined the number and estimated costs of all clinic visits, imaging and laboratory studies, and medical procedures that were generated as a direct result of extra-colonic findings at virtual colonoscopy.

RESULTS

We enrolled 143 subjects who underwent CTC followed by conventional colonoscopy. Data were available for 136 subjects, and 134 (98%) had at least one extra-colonic finding on CT. Evaluation of extra-colonic findings was performed in 32 subjects (24%). These subjects underwent 73 imaging studies, 30 laboratory studies, 44 clinic visits, 6 medical procedures, and 44 new or return outpatient visits over a mean of 38 months following the CTC. The most common findings causing further evaluation were lung nodules and indeterminate kidney lesions. No extra-colonic malignancies were found in this study. A total of $33,690 was spent in evaluating extra-colonic findings, which is $248 per patient enrolled.

CONCLUSIONS

The cost of the evaluation of extra-colonic findings following virtual colonoscopy may be much higher in actual practice than is suggested by prior studies. This will impact the cost-effectiveness of using virtual colonoscopy for asymptomatic colorectal cancer screening and underscores the importance of standardizing the reporting of extra-colonic findings to encourage appropriate follow-up.

Unsuspected extracolonic findings at screening CT colonography: clinical and economic impact

PURPOSE

To evaluate the frequency and estimated costs of additional diagnostic workup for extracolonic findings detected at computed tomographic (CT) colonography in a large screening cohort.

MATERIALS AND METHODS

This retrospective HIPAA-compliant study, which had institutional review board approval, evaluated extracolonic findings in 2195 consecutive asymptomatic adults (1199 women, 996 men; age range, 40-90 years; mean age, 58.0 years +/- 8.1 [standard deviation]) undergoing low-dose CT colonographic screening performed without contrast material at a single institution over a 20-month period. All diagnostic workups generated because of extracolonic findings were reviewed. Associated costs were estimated by using 2006 Medicare average reimbursement. Testing for statistical significance was performed by using the chi(2) and t tests.

RESULTS

Further diagnostic workup for unsuspected extracolonic findings was performed in 133 (6.1%) of 2195 patients, including 18 patients in whom additional workup was not recommended by the radiologist. Additional testing included ultrasonography (n = 64), CT (n = 59), magnetic resonance imaging (n = 11), other diagnostic imaging tests (n = 19), nonsurgical invasive procedures (n = 19), and surgical procedures (n = 22). Benign findings were confirmed in the majority of cases, but relevant new diagnoses were made in 55 (2.5%) patients, including extracolonic malignancies in nine patients. The mean cost per patient for nonsurgical procedures was $31.02 (95% confidence interval: $23.72, $38.94); that for surgical procedures was $67.54 (95% confidence interval: $38.62, $101.55).

CONCLUSION

Detection of relevant unsuspected extracolonic disease at CT colonographic screening is not rare, accounting for a relatively large percentage of cases in which additional workup was recommended. Judicious handling of potential extracolonic findings is warranted to balance the cost of additional workup against the potential for early detection of important disease, because many findings will prove to be of no clinical consequence.

Computed tomography colonography (virtual colonoscopy): climax of a new era of validation and transition into community practice

Colorectal cancer, which kills more than 50,000 patients every year in the United States and costs more than $6 billion in direct health costs, is a prime target for cancer prevention. Computed tomography colonography (CTC) has emerged as a minimally invasive, structural examination of the entire colon that can complement the current tools of cancer prevention and may improve patient compliance. Large trials have suggested a sensitivity of roughly 90% and specificity greater than 97% for CTC for patients with polyps >or= 10 mm. Bowel preparation by diet restriction, catharsis, and stool and fluid tagging are typically used. A prepless CTC protocol is an active area of research with a focus on improving patient compliance. Insurance coverage of CTC is a key factor affecting current dissemination and local and national coverage decisions are ongoing. CT examination of the abdomen allows visualization of extracolonic organs, where detection of additional disease must balance any unnecessary anxiety and testing. Estimates of CTC cost-effectiveness are generally favorable, but vary due to the high sensitivity of these models to costs, polyp sensitivity, compliance rates, and other parameters, which are difficult to accurately assess. Quality initiatives are being developed that will be key for implementation into community practice.

Extravascular incidental findings at multislice CT angiography of the abdominal aorta and lower extremity arteries: a retrospective review study

PURPOSE

To assess the frequency and clinical impact of extravascular incidental findings on routine CT angiography of abdominal aorta or lower extremity arteries.

MATERIALS AND METHODS

From January 2002 to July 2004, a total of 692 patients underwent CT angiography of abdominal aorta and lower extremity arteries. Two radiologists retrospectively reviewed by consensus cross-sectional images for the presence and clinical impact definition of extravascular findings. The revision of hospital charts, medical records, and all procedures' reports performed before and after CT angiography represented the standard of reference (SOR).

RESULTS

Only 373 out of 605 patients in whom extravascular findings were found had a SOR; in these patients CT angiography obtained a true-positive incidental rate of 98.9% (369/373). For the clinical impact definition of CT-angiography incidental findings, a concordance with SOR was obtained in 56.3% of patients, whereas a subsequent investigation was required in 183 patients (183/369, 49.6%). Among clinically relevant incidental findings, a total of 35 malignancies (35/894, 3.9%) were detected in 20 patients (20/423, 4.7%); in 15 patients (15/423, 3.5%) malignancy was unknown before CT-angiography exam.

CONCLUSIONS

A careful observation of cross-sectional images, even if "time consuming", is mandatory not only to assess vascular findings but also to avoid a misdiagnosis of clinical relevant extravascular findings.

Incidental findings in CT colonography: literature review and survey of current research practice

Incidental findings (IFs) of potential medical significance are seen in approximately 5-8 percent of asymptomatic subjects and 16 percent of symptomatic subjects participating in large computed tomography (CT) colonography (CTC) studies, with the incidence varying further by CT acquisition technique. While most CTC research programs have a well-defined plan to detect and disclose IFs, such plans are largely communicated only verbally. Written consent documents should also inform subjects of how IFs of potential medical significance will be detected and reported in CTC research studies.

Polyethylene glycol solution (PEG) plus contrast medium vs PEG alone preparation for CT colonography and conventional colonoscopy in preoperative colorectal cancer staging

PURPOSE

This study evaluated the usefulness of combined polyethylene glycol solution plus contrast medium bowel preparation (PEG-C preparation) followed by dual-contrast computed tomography enema (DCCTE) and conventional colonoscopy. The main purpose of these examinations is the preoperative staging of already known tumors.

MATERIALS AND METHODS

One hundred patients with colorectal tumors were alternately allocated to either a polyethylene glycol solution preparation (PEG preparation) group (n=50) or a PEG-C preparation group (n=50) before undergoing conventional colonoscopy and computed tomographic (CT) colonography. After conventional colonoscopy, multidetector row CT scans were performed. Air images were reconstructed for both groups; contrast medium images were additionally reconstructed for the PEG-C preparation group. DCCTE images were a composite of air images and contrast medium images without use of dedicated electronic cleansing software. Quality scores (the presence or absence of blind spots of the colon) were compared between the two groups.

RESULTS

Complete tumor images were obtained by DCCTE for all 50 (100%) lesions in the PEG-C preparation group, as compared with only nine of the 50 lesions (18%) in the PEG preparation group (air-contrast CT enema). The overall quality score in the PEG-C preparation group was significantly better than that in the PEG preparation group (P<0.0001).

CONCLUSIONS

DCCTE showed the entire colon without blind spots in nearly all patients in the PEG-C preparation group because the areas under residual fluid were reconstructed as contrast medium images. DCCTE and conventional colonoscopy after PEG-C preparation are feasible and safe procedures that can be used for preoperative evaluation in patients with colorectal cancer.

Screening for colon cancer

Colorectal cancer screening reduces mortality in individuals 50 years and older. Each of the screening tests currently available has advantages and limitations, and there is no consensus as to which test or combination of tests is best. What is clear, however, is that the rates of colorectal cancer screening remain low. This review summarizes the clinical evidence supporting colorectal cancer screening in the average risk population and in high risk groups, discusses the advantages and disadvantages of the available screening tests, outlines the currently recommended guidelines for screening based on risk category, and discusses new and emerging technologies for colorectal cancer screening.

Incidental Findings on Integrated PET/CT That Do Not Accumulate18F-FDG

OBJECTIVE

The purpose of this study was to report the prevalence of abnormalities that do not show increased 18F-FDG uptake on the CT component of integrated PET/CT in patients with non-small cell lung cancer.

MATERIALS AND METHODS

Images from all PET/CT studies performed consecutively between April and October 2003 on patients with non-small cell lung cancer were retrospectively reviewed. All abnormalities present on the CT component of the PET/CT scans that did not show abnormally increased 18F-FDG uptake were documented.

RESULTS

Three hundred twenty-one patients with non-small cell lung cancer (179 men, 142 women; mean age, 67 years; age range, 38-91 years) underwent initial staging (198/321 [62%]) or restaging (123/321 [38%]) PET/CT imaging during the study period. In 263 (82%) of the patients, CT showed 1,231 abnormalities that were not 18F-FDG avid. The abnormalities were located in the thorax (n = 650), abdomen and pelvis (n = 444), head and neck (n = 69), and bony skeleton (n = 68). In total, 298 (24%) of the abnormalities that were not 18F-FDG avid were located outside the range of a standard thoracic CT scan. The clinical importance of these abnormalities was classified as major (n = 48 [4%]), moderate (n = 465 [38%]), or minor (n = 718 [58%]). Four (1%) of the patients had findings of major clinical importance that did not show increased 18F-FDG uptake and were previously unsuspected.

CONCLUSION

Among patients with non-small cell lung cancer undergoing PET/CT, there is a high prevalence of CT abnormalities that do not show correlative 18F-FDG avidity but that may be clinically important.

Extracolonic Findings Identified in Asymptomatic Adults at Screening CT Colonography

OBJECTIVE

The purpose of this article is to demonstrate the wide variety of extracolonic findings that may be encountered at screening CT colonography (CTC) in asymptomatic adults as well as to discuss the pertinent issues regarding the detection of potential abnormalities in a healthy population.

CONCLUSION

Regardless of whether extracolonic evaluation resulting from CTC screening is viewed as a net benefit or liability, it is an unavoidable responsibility that must be handled with care by the interpreting radiologist. Although many potential abnormalities may be questioned, the pretest probability of clinically relevant disease is quite low in average-risk asymptomatic adults, which may influence subsequent management decisions.

Virtual colonoscopy for colorectal cancer screening: current status

Computed tomography colonography (CTC) (also known as ‘virtual colonoscopy’) is a noninvasive method of imaging the colon using helical CT. Although CTC has been shown to be useful for certain clinical indications, it has not yet been endorsed as a colorectal cancer screening test. The purpose of this article is to review the current status of CTC for colorectal cancer screening. CTC is an accurate method to detect colonic polyps and to select patients who would benefit from colonoscopy. The major advantages of CTC over conventional colonography include its relatively low risk and greater tolerance by patients. In this article, the CTC procedure and results of clinical trials are reviewed, as well as potential pitfalls related to CTC performance and interpretation. Finally, radiation dose, the discovery of incidental extracolonic findings with CTC, bowel preparation methods, and computer-aided diagnosis are addressed.

Extracolonic abnormalities discovered incidentally at CT colonography in a male population

PURPOSE

To evaluate prospectively the prevalence of incidental extracolonic findings at computed tomographic (CT) colonography and to estimate the cost of their imaging work-up in male patients with high and those with average risk of colorectal cancer.

MATERIALS AND METHODS

This study was approved by the institutional review board, and informed consent was obtained from all patients. The study was compliant with requirements of the Health Insurance Portability and Accountability Act. CT colonography was performed in 500 men (mean age, 62.5 years). Of these patients, 194 (38.8%) were at average risk for colorectal cancer and presented for routine screening. The other 306 (61.2%) were at high risk for colorectal cancer. Extracolonic findings were recorded and categorized as either clinically important or clinically unimportant. Clinically important findings were defined as those that necessitated further diagnostic studies or medical or surgical follow-up. The cost of additional imaging required to further characterize important lesions was estimated. Chart review was performed (mean length of follow-up, 3.6 years) to determine whether any important findings were missed at CT colonography. The Fisher exact test was used to determine whether there was a difference between the percentages of average- and high-risk patients with extracolonic findings.

RESULTS

Of the 500 patients in the study, 315 (63.0%) had extracolonic findings, and 45 (9.0%) had clinically important extracolonic findings. Of the 596 extracolonic findings identified, 50 (8.4%) were thought to be clinically important. The mean additional cost to work up important findings was $28.12 per CT colonographic examination. There were no significant differences between average-risk and high-risk patients in the percentages of extracolonic findings (P = .25) or clinically important extracolonic findings (P = .11).

CONCLUSION

A substantial number of both average- and high-risk patients undergoing CT colonography will be found to have clinically important extracolonic findings. There was no increased morbidity or mortality associated with the additional evaluation of extracolonic findings. The cost of evaluating these lesions is low, given the potential for positive effects on patient care.

Extracolonic findings at CT colonography

CT colonography (CTC), also referred to as virtual colonoscopy, is a noninvasive CT examination of the colon. Usually performed without IV contrast, it allows detection of both intraluminal and extraluminal (extracolonic) disease. Several studies demonstrate that although extracolonic disease at CTC is found in the majority of patients, the detection of previously undiagnosed highly important findings (HIF) is much lower. The number of HIF can vary depending on the definition of an HIF, the patient population, as well as technical factors. This article will discuss the incidence and implication of detecting extracolonic findings at CTC.

Extracolonic findings at CT colonography

This review focuses on the detection of extracolonic findings at CT colonography (CTC). Since its introduction, it has been regarded as a promising alternative to conventional colonoscopy for the detection of colorectal polyps and cancers. Unlike conventional colonoscopy and barium enema, CTC allows evaluation not only of the colon but also visualization of the lung bases, the abdomen, and the pelvis. CTC is performed with thin sections (1-5 mm) and small intervals (0.5-2 mm), enabling superb image reconstruction. The ability to evaluate the extracolonic structures can present a clinical dilemma. On the one hand, CTC may incidentally demonstrate asymptomatic malignant diseases or other clinically important conditions, thus possibly reducing morbidity or mortality. On the other hand, CTC may reveal numerous findings of no clinical relevance; this could result in costly additional diagnostic examinations with an increase in morbidity and overall negative impact on patients' health. In this article, extracolonic findings at CTC will be reviewed and the potential benefits and disadvantages will be presented.

Colonography by computed tomography

Computed tomographic colonography ('virtual colonoscopy') has shown promising results in the detection of large (> or = 10 mm) polyps in populations with a high prevalence of polyps. Recent studies in low prevalence populations, however, show variable results in sensitivity, ranging from 55% to 94% for the detection of patients with polyps measuring 10 mm or longer. Therefore questions have been raised about computed tomographic colonography as a screening method, probably the most valuable use of this technique. This article describes possible causes of these remarkable differences as well as advances in computed tomographic colonography.

Colon imaging: computed tomographic colonography

Computed tomographic colonography (CTC, virtual colonoscopy) is an attractive modality with which to image the colon. Many different techniques are available; moreover, during the last several years, advances in hardware and software have been remarkable. Evidence to this date suggests that CTC has varying sensitivity for detection of large colonic lesions, largely dependent on technique and the method of study. A variety of issues related to CTC are reviewed, including evolution of CTC, sensitivity and specificity of CTC, patient experience, extracolonic lesions, advances in colon preparation, and training. It is clear that CTC has great promise, but also that many questions about its use remain to be answered.

Importance of extracolonic findings at IV contrast medium-enhanced CT colonography versus those at non-enhanced CT colonography

To compare the clinical importance of extracolonic findings at intravenous (IV) contrast-enhanced CT colonography versus those at non-enhanced CT colonography. IV contrast medium-enhanced (n=72) and non-enhanced (n=30) multidetector CT colonography was performed in 102 symptomatic patients followed by conventional colonoscopy on the same day. The impact of extracolonic findings on further work up and treatment was assessed by a review of patient records. Extracolonic findings were divided into two groups: either leading to further work up respectively having an impact on therapy or not. A total of 303 extracolonic findings were detected. Of those, 71% (215/303) were found on IV contrast-enhanced CT, and 29% (88/303) were found on non-enhanced CT colonography. The extracolonic findings in 25% (26/102) of all patients led to further work up or had an impact on therapy. Twenty-two of these patients underwent CT colonography with IV contrast enhancement, and four without. The percentage of extracolonic findings leading to further work up or having an impact on therapy was higher for IV contrast-enhanced (31%; 22/72) than for non-enhanced (13%; 4/30) CT scans (P=0.12). IV contrast-enhanced CT colonography produced more extracolonic findings than non-enhanced CT colonography. A substantially greater proportion of findings on IV contrast-enhanced CT colonography led to further work up and treatment than did non-enhanced CT colonography.

Low-dose CT colonography in children: initial experience, technical feasibility, and utility

BACKGROUND

CT colonography (CTC) is utilized as a diagnostic tool in the detection of colon polyps and early colorectal cancer in adults. Large studies in the literature, although focused on adult populations, have shown CTC to be a safe, accurate, non-invasive technique.

OBJECTIVE

We evaluated the technical feasibility of CTC in children using a low-dose technique.

MATERIALS AND METHODS

From November 2001 to April 2004 we evaluated eight patients (3-17 years) with non-contrast CTC. Seven of the patients had CTC, followed by standard colonoscopy (SC) the same day; in one patient, CTC followed a failed SC. CTC results were compared to results of SC. The estimated effective dose from each CTC was calculated and compared to that of standard barium enema.

RESULTS

CTC results were consistent with those of SC. Sensitivity for polyps 5-10 mm was 100%, and sensitivity for polyps 10 mm and larger was 66.7%. The estimated mean effective dose was 2.17 mSv for CTC, compared to the 5-6 mSv for a standard air-contrast barium enema in a small child.

CONCLUSION

Our initial experience shows CTC in children is well-tolerated, safe, and useful. The procedure can be performed successfully with a low radiation dose, and preliminary results compare well with SC.

Incidental lesions found on CT colonography: their nature and frequency

CT colonography has been used to detect colonic polyps and cancers, but its effect in practice will also be influenced by the frequency with which extracolonic lesions of various types are detected. We performed a systematic review of the types of incidental lesions found on CT colonography. This is necessary to model the benefits and harms of detecting extracolonic lesions. Primary clinical studies of extracolonic findings on CT colonography were identified from electronic databases, scanning reference lists and hand searches of relevant journals and conference proceedings. A data collection proforma was used to collect information on extracolonic findings. 17 discreet studies were identified, involving 3488 patients. In total 40% of patients were recorded to have abnormalities and many had more than one abnormality. Nearly 14% of patients had further investigations and 0.8% were given immediate treatment. Extracolonic cancers were detected in 2.7% (0.9% had N0M0 cancers) and 0.9% had an aortic aneurysm. The number of extracolonic findings was high in all studies. While only a small population were judged "important", the prevalence of serious lesions outside the colon was nevertheless higher than in many other screening programs.

Virtual colonoscopy: Issues in implementation

The following issues and requirements related to the implementation of a CT colonography (CTC) service are important: (i) policies are needed regarding the indications for CTC. Concomitant with this is the need for education of potential referrers and patients. Expectations of the procedure, particularly by general practitioners, may be unrealistic and indications for referral may otherwise be inappropriate. At present there is not general acceptance of CTC for screening asymptomatic persons; (ii) a flexible approach to CT protocols is useful, dependent on the indication for and clinical context of referral, the age and body habitus of the patient; (iii) attention to the issues related to the special skills required by the reporting radiologist. While there is a temptation to regard CTC interpretation as an extension of skills used in interpreting other cross-sectional images, there is a need to realise that there are skills required specific to CTC and there should be adequate provision for training; (iv) matters related to reporting, such as reporting format, and lesions that will be reported/not reported; and (v) informed consent from the patient. Information should be provided with regard to the limitations of CTC, the implications of a positive finding and radiation dosage.