Computed Tomography Colonography as a Sensible Option for Colorectal Cancer Screening: Evidence Based on Metanalysis / Colonografia por tomografia computadorizada como uma opção sensível para o rastreamento do câncer colorretal: Evidências baseadas em metanálise

Abstract Objective This metanalysis aimed to evaluate the sensitivity and specificity of computed tomography colonography in colorectal polyp detection. Methods A literature search was performed in the PubMed and Web of Science databases. Results A total of 1,872 patients (males 57.2%, females 42.8%) aged 49 to 82 years old (mean age 59.7 ± 5.3 years) were included in this metanalysis. The estimated sensitivity of computed tomography colonography was 88.4% (46.3-95.7%, coefficient of variation [CV]=28.5%) and the estimated specificity was 73.6% (47.4-100.0%, CV=37.5%). For lesions up to 9mm, the sensitivity was 82.5% (62.0-99.9%, CV =25.1%) and the specificity was 79.2% (32.0-98.0%, CV=22.9%). For lesions>9mm, the sensitivity was 90.2% (64.0-100.0%, CV=7.4%) and the specificity was 94.7% (80.0-100.0%, CV=6.2%). No statistically significant differences in sensitivity according to the size of the lesion were found (p=0.0958); however, the specificity was higher for lesions>9mm (p<0.0001). Conclusions Most of the studies analyzed in the present work were conducted before 2010, which is about a decade after computed tomography colonography started being indicated as a screening method by European and American guidelines. Therefore, more studies aimed at analyzing the technique after further technological advancements are necessary, which could lead to the development of more modern devices.

Resumo Objetivo Esta meta-análise teve como objetivo avaliar a sensibilidade e especificidade da colonografia por tomografia computadorizada na detecção de pólipos colorretais. Métodos Foi realizada uma pesquisa bibliográfica nas bases de dados da PubMed e da Web of Science. Resultados Um total de 1.872 pacientes, 57,2% homens e 42,8% mulheres, com idades entre 49 a 82 anos de idade (média de 59,7 ± 5,3 anos) foram incluídos nesta meta análise. A sensibilidade da colonografia por tomografia computadorizada foi estimada em 88,4% (46,3-95,7%; coeficiente de variância [CV]=28,5%) e a especificidade em 73,6% (47,4%-100,0%; CV=37,5%). Para lesões de até 9mm, a sensibilidade foi de 82,5% (62,0-99,9%; CV=25,1%) e a especificidade de 79,2% (32,0-98,0%; CV=22,9%). Para lesõesmaiores que 9mm, a sensibilidade foi de 90,2% (64,0-100,0%; CV=7,4%) e a especificidade de 94,7% (80,0-100,0%; CV=6,2%). Não houve diferença estatisticamente significante entre as sensibilidades por tamanho da lesão (p=0,0958), porém a especificidade foi maior em lesões acima de 9mm (p<0,0001). Conclusão A maioria dos estudos analisados no presente trabalho foi realizada antes de 2010, cerca de uma década depois que a colonografia por tomografia computadorizada passou a ser indicada como método de triagem pelas diretrizes europeias e americanas. Portanto, são necessários mais estudos com o objetivo de analisar a técnica apósmaiores avanços tecnológicos, o que poderia levar ao desenvolvimento de dispositivos mais modernos.

Using computed tomography colonography in patients at high risk of colorectal cancer - a prospective study in a university hospital in South America

OBJECTIVES: The purpose of our study was to report the results of the implementation of computed tomography colonography in a university hospital setting serving a Brazilian population at high risk of colorectal cancer. METHODS: After creating a computed tomography colonography service in our institution, 85 patients at high risk of colorectal cancer underwent computed tomography colonography followed by a same-day optical colonoscopy from September 2010 to May 2012. The overall accuracy of computed tomography colonography in the detection of lesions ≥6 mm was compared to that of optical colonoscopy (direct comparison). All colonic segments were evaluated using quality imaging (amount of liquid and solid residual feces and luminal distension). To assess patient acceptance and preference, a questionnaire was completed before and after the computed tomography colonography and optical colonoscopy. Fisher's exact test was used to measure the correlations between colonic distension, discomfort during the exam, exam preference and interpretation confidence. RESULTS: Thirteen carcinomas and twenty-two lesions ≥6 mm were characterized. The sensitivity, specificity and accuracy of computed tomography colonography were 100%, 98.2% and 98.6%, respectively. Computed tomography colonography was the preferred method of investigation for 85% of patients. The preparation was reported to cause only mild discomfort for 97.6% of patients. According to the questionnaires, there was no significant relationship between colonic distension and discomfort (p>0.05). Most patients (89%) achieved excellent bowel preparation. There was a statistically significant correlation between the confidence perceived in reading the computed tomography colonography and the quality of the preparation in each colonic segment (p≤0.001). The average effective radiation dose per exam was 7.8 mSv. CONCLUSION: It was possible to institute an efficient computed ...

Colonografia por tomografia computadorizada versus colonoscopia óptica no rastreamento do câncer colorretal: uma revisão sistemática / Computed tomographic colonography versus optical colonoscopy in colorectal cancer screening: a systematic review

Objetivo: comparar, por meio de uma revisão sistematizada, a colonografia por tomografia (CTC) versus colonoscopia óptica (CO) em relação ao rastreamento e vigilância do câncer colorretal (CCR). Método: foram analisados estudos em inglês e português sobre CTC e CO realizados em humanos adultos de ambos os sexos, publicados no MedLine/PubMed (National Library of Medicine) e no Scielo (Scientific Eletronic Library Online) no período entre 1990 a 2013. A busca incluiu combinações de palavras-chave (Colonoscopy, Cólonoscopic surgery, virtual Colonoscopy, CT Colonography) com boolianos AND e OR. Os critérios de inclusão foram ensaios clínicos controlados e randomizados, estudo de revisão, revisões sistemáticas com ou sem metanálise, consenso, pacientes adultos, pacientes assintomáticos ou sintomáticos. Os critérios de exclusão foram pacientes inapropriados e somente em resumo. Resultados: foram selecionados 26 estudos com melhor abordagem dos desfechos selecionados para rastreamento e vigilância do câncer (CCR). O número global de pacientes submetidos às variáveis foi de 397.342 indivíduos. Os valores das variáveis de sensibilidade e especificidade para detecção de pólipos maior ou igual a 10mm e câncer colorretal apresentam percentagens semelhantes, sendo a taxa de sensibilidade da CTC diretamente proporcional ao tamanho do pólipo. A taxa de pacientes submetidos à CO após a CTC variou de 12% a 36,4%; destes, 3,8% apresentaram lesões significativas. A análise da taxa de CO incompleta obteve um padrão de variações entre 11% e 64,8%. A aceitação dos pacientes, tanto para o preparo intestinal como para o procedimento, foi maior para a CTC. Os achados extracólicos nos pacientes submetidos à CTC foram analisados e variaram de 58 a 69%. As complicações dos dois métodos foram baixas, maior na CO. Conclusão: as diferenças na sensibilidade e especificidade entre a CO e a CTC no rastreamento e vigilância do CCR não são relevantes. A indicação de CO após CTC deve seguir critérios consensuais para evitar aumento de custos e de riscos ao paciente. Pacientes com CO incompleta têm indicação de realizar CTC por se enquadrar no grupo de alto risco para desenvolver CCR. A aceitação dos pacientes na realização dos dois métodos é boa e não representa impedimento ao rastreamento e vigilância do CCR. Os achados extracólicos na CTC é um benefício adicional para o paciente. As complicações inerentes aos dois métodos não superam o impacto positivo dos mesmos na prevenção do CCR.

Objective: to compare in a systematic review the computed tomographic Colonography (CTC) and the optical Colonoscopy (OC) methods for the screening and monitoring of colorectal cancer (CRC). Method: english and portuguese studies on CTC and OC that were carried out on adult humans of both genders that had been published in MedLine/PubMed (National Library of Medicine) and SciELO (Scientific Electronic Library Online) between 1990 and 2013 were analyzed. The search included combinations of keywords (Colonoscopy, Cólonoscopic surgery, virtual Colonoscopy, CT Colonography, etc.) with the AND and OR Boolean operators. The inclusion criteria were as follows: controlled and randomized clinical trials, review studies, systematic reviews with or without meta-analysis, consensus, adult patients, and asymptomatic or symptomatic patients. The exclusion criteria were as follows: unsuitable patients and manuscripts only containing abstracts. Results: twenty-six studies that included the selected outcomes for screening for and monitoring CRC were selected. The overall number of patients analyzed was 397, 342 individuals. The sensitivity and specificity percentages for the detection of polyps greater than or equal to 10 mm and for colorectal cancer were similar between the two methods, and the CTC sensitivity rate was directly proportional to the size of the polyp. The rate of patients undergoing OC after CTC ranged from 12% to 36.4%, and of these patients, 3.8% had significant lesions. The analysis of the incomplete OC rate found variation ranging from 11 to 64.8%. The acceptance rates of the patients for both intestinal preparation and for the procedure were greater for CTC. The extracolic findings in patients undergoing CTC were analyzed and ranged from 58 to 69%. Complications were minimal for the patients undergoing both methods and higher for those in the OC group. Conclusion: the differences in the sensitivity and specificity of OC and CTC in screening and monitoring CRC are not significant. The indication of OC after CTC must follow agreed-upon criteria to avoid increased costs and risks to the patient. Patients with an incomplete OC should undergo CTC, as they fall within the high risk group for developing CRC. The acceptance of patients undergoing the two methods is good and does not represent an impediment to screening for and monitoring CRC. The extracolic findings, in the CTC group, is an additional benefit to the patient. The complications inherent in the two methods do not outweigh their positive impacts in the prevention of CRC.

Virtual Colonoscopy is Feasible in Geriatric Patients-A Case Series.

Virtual colonoscopy (VC) or computed tomographic colonography is now an established imaging test in the detection of colorectal cancer. Like other modern imaging tests VC requires highly compliant patients (rectal air insufflation, breath hold, imaging in supine and prone position). As patients are getting older VC is also requested in the elderly. In a case series of geriatric patients (mean age 83 years) undergoing VC after incomplete optical colonoscopy 92.7% of all colonic segments were adequately visualized. VC seems to be feasible in geriatric patients and has therefore replaced barium enema in this patient group after incomplete optical colonoscopy at our department.

Preferência do paciente no rastreamento do câncer colorretal: uma comparação entre colonografia por tomografia computadorizada e colonoscopia / Patient preferences toward colon cancer screening: a comparison between computed tomography colonography and conventional colonoscopy

OBJETIVO: Avaliar o grau de aceitação do paciente submetido a colonografia por tomografia computadorizada (CTC) em comparação com a colonoscopia, quando realizadas para rastreamento de doença colorretal. MATERIAIS E MÉTODOS: Cinquenta pacientes com suspeita de doença colorretal foram submetidos a CTC e colonoscopia. Questionários foram aplicados antes e após a realização da CTC e após a colonoscopia. Graduou-se o desconforto esperado e experimentado antes e após a realização da CTC e da colonoscopia, bem como a preferência do paciente por exame. RESULTADOS: Em relação à CTC, antes de iniciar o exame 18 por cento dos pacientes afirmaram esperar pouco desconforto, 78 por cento, desconforto moderado e 4 por cento, muito desconforto. Após a realização do exame, 72 por cento dos pacientes relataram pouco desconforto, 26 por cento, desconforto moderado e apenas um (2 por cento) dos pacientes referiu muito desconforto. Após a realização da colonoscopia, 86 por cento dos pacientes relataram preferência pela CTC. O grau de distensão colônica e a quantidade de fluido residual não influenciaram na preferência dos pacientes. CONCLUSÃO: Os pacientes preferiram a CTC à colonoscopia, não havendo relação estatística com o grau de distensão colônica na CTC e a eficiência do preparo intestinal.

OBJECTIVE: To assess the degree of acceptance of patients undergoing computed tomography colonography (CTC) in comparison with colonoscopy in the screening of colorectal disease. MATERIALS AND METHODS: Fifty patients with suspected colorectal disease underwent CTC and colonoscopy. Questionnaires were administered before and after the performance of the CTC and after the colonoscopy. The discomfort expected and experienced before and after the performance of both procedures as well as the patients' preference for each method were evaluated. RESULTS: As regards CTC, before the procedure, 18 percent of the patients reported expecting little discomfort, 78 percent, mild discomfort, and 4 percent, a lot of discomfort. After the procedure, 72 percent of the patients reported little discomfort, 26 percent, mild discomfort, and only one (2 percent) of the patients reported a lot of discomfort. Upon completion of the colonoscopy, 86 percent of the patients reported their preference for CTC. The degree of colonic distention and residual amount of fluid had no influence on the patients' preference. CONCLUSION: CTC was preferred to colonoscopy, with no statistical relationship with the degree of colonic distention at CTC and efficiency of bowel preparation.

Distensión colónica con bomba de CO2: Impacto en el disconfort del paciente en los estudios de colonoscopía virtual / Colonic distention with CO2 insufflation: Impact on the patient's discomfort in virtual colonoscopy studies

Objetivos. Analizar el rol de la distensión colónica con CO2 y su influencia en el disconfort del paciente y en el tiempo de duración de la colonoscopía virtual en nuestra práctica diaria. Materiales y Métodos. Se estudiaron 200 pacientes, 50 insuflados con aire ambiental y 150 con CO2. Los estudios se realizaron con un equipo multidetector de 64 filas con cortes de 2 mm de espesor, 120 kV y 50 mAs. En todos los pacientes se efectuó una adquisición en decúbito supino y otra en prono. Se calculó el tiempo total del procedimiento en cada grupo y se utilizó una prueba "t de Student" para calcular las diferencias. Los pacientes completaron un cuestionario en referencia al grado de disconfort percibido. Se utilizó una escala de 0 a 3: 0- sin disconfort, 1- disconfort leve, 2- moderado y 3- severo. Se utilizó un test de proporciones para calcular las diferencias del grado de disconfort entre ambos grupos. Resultados. El tiempo total de los procedimientos fue de 30,5 minutos para los realizados con CO2 y 35,4 minutos para los efectuados con aire ambiental, con una diferencia de -4,9 min (p=0,0003). En la valoración del disconfort, en el grupo con insuflado con aire ambiental, el 44% de los pacientes manifestó un grado de disconfort moderado, mientras que en el grupo con CO2 el 76% manifestó ausencia de disconfort. Conclusiones. La colonoscopía virtual realizada con insuflación de CO2 permitió disminuir en forma parcial el tiempo total del examen y, de modo significativo, el disconfort durante y después del examen.

Objectives. To analyze the role of colonic distention with CO2 and its influence on patients' discomfort and the duration of the virtual colonoscopy procedure in our daily practice. Materials and Methods. Two hundred patients were evaluated, 50 were insufflated using room air and 150 with CO2. The studies were performed with a 64-row CT scanner using 2-mm slice thickness, 120 kV and 50 mAs. In all patients, scans were acquired both in prone and supine positions. We calculated the total procedure time in each group; a Student's t-test was used to calculate the differences. Patients completed a questionnaire about the degree of discomfort perceived. We used a scale of 0 to 3: 0- no discomfort, 1- mild, 2- moderate and 3- severe discomfort. We used a test of proportions to calculate the differences in the degree of discomfort between the two groups. Results. The total procedure time was 30.5 minutes for studies performed with CO2 and 35.4 minutes for those performed with room air, with a difference of -4.9 min (p =0.0003). As regards the assessment of discomfort, in the group insufflated with room air, 44% of patients reported a moderate degree of discomfort, while in the group insufflated with CO2, 76% of the patients expressed no discomfort. Conclusions. Virtual colonoscopy performed with CO2 insufflation partially reduced the total procedure time, and significantly reduced discomfort during and after the procedure.

Efficacy of Barium-Based Fecal Tagging for CT Colonography: a Comparison between the Use of High and Low Density Barium Suspensions in a Korean Population - a Preliminary Study

OBJECTIVE: This preliminarily study was designed to determine and to compare the efficacy of two commercially available barium-based fecal tagging agents for CT colonography (CTC) (high-density [40% w/v] and low-density [4.6% w/v] barium suspensions) in a population in Korea. MATERIALS AND METHODS: In a population with an identified with an average-risk for colorectal cancer, 15 adults were administered three doses of 20 ml 40% w/v barium for fecal tagging (group I) and 15 adults were administered three doses of 200 ml 4.6% w/v barium (group II) for fecal tagging. Excluding five patients in group I and one patient in group II that left the study, ten patients in group I and 14 patients in group II were finally included in the analysis. Two experienced readers evaluated the CTC images in consensus regarding the degree of tagging of stool pieces 6 mm or larger. Stool pieces were confirmed with the use of standardized CTC criteria or the absence of matched lesions as seen on colonoscopy. The rates of complete fecal tagging were analyzed on a per-lesion and a per-segment basis and were compared between the patients in the two groups. RESULTS: Per-lesion rates of complete fecal tagging were 52% (22 of 42; 95% CI, 37.7-66.6%) in group I and 78% (28 of 36; 95% CI, 61.7-88.5%) in group II. The difference between the two groups did not reach statistical significance (p = 0.285). The per-segment rates of complete tagging were 33% (6 of 18; 95% CI, 16.1%-56.4%) in group I and 60% (9 of 15; 95% CI, 35.7%-80.3%) in group II; again, the difference between the two groups did not reach statistical significance (p = 0.171). CONCLUSION: Barium-based fecal tagging using both the 40% w/v and the 4.6% w/v barium suspensions showed moderate tagging efficacy. The preliminary comparison did not demonstrate a statistically significant difference in the tagging efficacy between the use of the two tagging agents, despite the tendency toward better tagging with the use of the 4.6% w/v barium suspension.

Fundamental Elements for Successful Performance of CT Colonography (Virtual Colonoscopy)

There are many factors affecting the successful performance of CT colonography (CTC). Adequate colonic cleansing and distention, the optimal CT technique and interpretation with using the newest CTC software by a trained reader will help ensure high accuracy for lesion detection. Fecal and fluid tagging may improve the diagnostic accuracy and allow for reduced bowel preparation. Automated carbon dioxide insufflation is more efficient and may be safer for colonic distention as compared to manual room air insufflation. CT scanning should use thin collimation of < or =3 mm with a reconstruction interval of < or =1.5 mm and a low radiation dose. There is not any one correct method for the interpretation of CTC; therefore, readers should be well-versed with both the primary 3D and 2D reviews. Polyps detected at CTC should be measured accurately and reported following the "polyp size-based" patient management system. The time-intensive nature of CTC and the limited resources for training radiologists appear to be the major barriers for implementing CTC in Korea.

Diagnostic Performance of CT Colonography for the Detection of Colorectal Polyps

OBJECTIVE: To investigate the diagnostic value of CT colonography for the detection of colorectal polyps. MATERIALS AND METHODS: From December 2004 to December 2005, 399 patients underwent CT colonography and follow-up conventional colonoscopy. We excluded cases of advanced colorectal cancer. We retrospectively analyzed the CT colonography findings and follow-up conventional colonoscopy findings of 113 patients who had polyps more than 6 mm in diameter. Radiologists using 3D and 2D computer generated displays interpreted the CT colonography images. The colonoscopists were aware of the CT colonography findings before the procedure. RESULTS: CT colonography detected 132 polyps in 107 of the 113 patients and conventional colonoscopy detected 114 colorectal polyps more than 6 mm in diameter in 87 of the 113 patients. The sensitivity of CT colonography analyzed per polyp was 91% (41/45) for polyps more than 10 mm in diameter and 89% (101/114) for polyps more than 6 mm in diameter. Thirteen polyps were missed by CT colonography and were detected on follow-up conventional colonoscopy. CONCLUSION: CT colonography is a sensitive diagnostic tool for the detection of colorectal polyps and adequate bowel preparation, optimal bowel distention and clinical experience are needed to reduce the rate of missing appropriate lesions.

Papel de la colonoscopia virtual en la evaluación de la enfermedad no polipoidea en pediatría / Virtual colonoscopy in pediatrics. Its role in the evaluation of non-polypoid lesions

Virtual colonoscopy is a new non-invasive method useful in the evaluation of elevated lesions. Due to the fact that the method has only been used for that purpose in the adult and pediatric population, the aim of this paper is to determine its utility in pediatric pathologies other than elevated lesions. Twenty patients with abdominal pain, chronic constipation and defecation problems were evaluated. The studies were performed with a 4-row CT scanner, using 1 mm slice thickness collimation. The acquisition time was 7-12 seconds. Neither sedation nor anesthesia was necessary. CT colonography can generate images similar to those from barium enema studies, without the use of barium contrast, avoiding related complications. The CT exam also provides information about the rest of the abdominal organs. All studies were performed without complications. Patients with Hirschprung disease, colorectal malformations, post-surgical complications and psichogenic megacolon were detected.

La colonoscopia virtual es una modalidad diagnóstica no invasiva para la valoración de enfermedad colorrectal sobre elevada. Dada su escasa aplicación en la población pediátrica, el objetivo de este trabajo es determinar su utilidad en otras patologías pediátricas. Se evaluaron 20 pacientes con síntomas como dolor abdominal, constipación crónica y dificultad en la defecación. Los estudios se realizaron con un tomógrafo de 4 filas de detectores, con cortes de 1 mm de espesor. La adquisición de las imágenes se realizó en decúbito supino, sin necesidad de apnea ni de anestesia. El tiempo de adquisición fue de aproximadamente 7 a 12 segundos. La colonoscopia virtual permite obtener imágenes similares a las de un colon por enema sin utilizar ningún tipo de contraste, por lo que evita posibles complicaciones. A ello se agrega la extrema rapidez del estudio, sin necesidad de movilizar al paciente. Además, brinda información adicional sobre el resto de los órganos abdominales, lo que determina un estudio más completo del paciente. No se observaron complicaciones. Se detectaron diversas patologías pediátricas como enfermedad de Hirschprung, megacolon psicógeno, malformaciones anorrectales y complicaciones posquirúrgicas

Colonoscopia virtual / Virtual colonoscopy

Since the first report in 1994 virtual colonoscopy or CT colonography has had an explosive development due to the improvement in hardware and software. The multidetector CT has allowed faster studies with better images due to better multiplanar reconstructions and its speed avoiding the artifact of the breathing or bowel peristalsis. The new software has allowed to obtain better 3D images and faster reconstruction with shorter interpretation. This development, the use of standarized protocol plus the experience of trained radiologists have obtained sensitivity and specificity over 85% and 95% in polyps smaller and larger than 10 mm respectively. These results and the lower price of virtual colonoscopy in the United States compared with fibrocolonoscopy has done this technique a real alternative for the screening of colorectal cancer side by side with fibrocolonoscopy.

Desde la primera publicación sobre colonoscopía virtual o colonografía por tomografía computada (TC) esta técnica ha tenido un explosivo crecimiento especialmente dado por el desarrollo en el hardware, específicamente por la introducción de la TC multicorte que ha permitido obtener mejores imágenes gracias a la mayor velocidad que ha obviado los artefactos dados por el movimiento respiratorio y el peristaltismo intestinal. Otro factor importante en su desarrollo ha sido el gran avance en los programas computacionales (software) que han automatizado la técnica obteniendo recons-trucciones 3D de mejor calidad y en menor tiempo. El notable desarrollo tecnológico sumado a la estandarización de la técnica y la mayor experiencia lograda en diferentes centros ha hecho que en la actualidad la sensibilidad y especificidad de la colonografía sobrepasen el 85 y 95% para los pólipos menores y mayores de 1 cm, respectivamente. Todo esto, sumado a la estandarización de la técnica ha llevado a posicionarla como una alternativa válida y en estrecha competencia con la fibrocolonoscopía en la pesquisa de los pólipos de colon.

Comparison of Colonoscopy and Virtual Colonoscopy for the Detection of Colorectal Polyps / 대한소화기내시경학회지

BACKGROUND/AIMS: Virtual colonoscopy using abdominal spiral computed tomography scanning allows total colonic evaluation with minimal invasiveness. We compared the performance of virtual colonoscopy and colonoscopy for the detection of colorectal polyps. METHODS: We performed colonoscopy before the virtual colonoscopy. Virtual colonoscopy was performed immediately before the colonoscopic polypectomy in 24 adults (16 men and 8 women: mean age, 59 years). RESULTS: A total of 48 polyps were found by colonoscopy. Virtual colonoscopy identified 20 of 28 polyps that were 10 mm or more in diameter (71%), 3 of 4 that were 6 to 9 mm (75%), and 9 of 16 that were 5 mm or smaller (56%). Overall sensitivity of virtual colonoscopy for colorectal polyps was 67%. CONCLUSIONS: Our result of virtual colonoscopy showed lower sensitivity for detection of significant colorectal lesions than previously reported studies. Further large group study may be needed to determine the usefulness of virtual colonoscopy.

Early Experience of Virtual Colonoscopy on Colorectal Cancer

PURPOSE: Virtual colonoscopy (VC) is a newly developing non-invasive technique used to detect polyps and cancers of the colon. The aim of this study is to assess the efficacy of VC in the detection of synchronous polyps or cancers in preoperative patients as well as metachronous polyps of postoperative colorectal cancer patients. METHODS: Both VC and conventional colonoscopy (CFS) were performed on 40 patients with colorectal cancer (10 cases of preoperative state and 30 cases of postoperative follow-up) during Sep. 2002 to June 2003 in Daegu Catholic Medical Centre, Catholic University of Daegu, Republic of Korea. The success rate and the detection rate of polyps or cancers along with the locations and sizes of masses and the findings of anastomotic site were compared between VC and CFS. RESULTS: The entire colon was clearly visualized by CFS in all cases. In the preoperative group, VC was successfully performed in 8 out of 10 cases (80%). 8 out of 10 cancers, 4 out of 4 polyps (5 mm or more in diameter) and 3 out of 6 polyps (5 mm or less in diameter) were identified. The success rate of VC in the postoperative group were 58% of low anterior resection (LAR) from cecum to hepatic flexure, 89% of LAR, 45% of right hemicolectomy (RHC) from hepatic flexure to splenic flexure, 63% of LAR, 45% of RHC from splenic flexure to sigmoid colon, and 53% of LAR, 72% of RHC in rectum. The causes of failure were inadequate bowel distension and retained fluid. In postoperative group, VC identified only 3 of 7 polyps(5 mm or more in diameter), 1 of 10 polyps (5 mm or less in diameter) and 1 of 1 recurrent cancer. The anastomotic site was clearly seen by VC in 9 of 19 cases (47%) of LAR and 3 of 11 cases (27%) of RHC. VC also identified 28 extracolonic findings. CONCLUSIONS: Although the efficacy of VC in postoperative colorectal cancer follow up seems to be disappointing, but it can be used as an alternative method for patients with incomplete conventional colonoscopy due to anastomotic site stricture or for other failed cases. Further technological advancement of VC is needed in order for it to replace conventional colonoscopy as a postoperative follow-up test.

Diagnostic value of multi-slice spiral CT colonoscopy in colorectal neoplasms / 第三军医大学学报

Objective To study the value of multi-slice spiral CT virtual colonoscopy(CTVC) in diagnosing colorectal neoplasms.Methods Forty-one patients with colorectal neoplasms proven by colonoscopy were further scanned successively by a 16-slice spiral CT with thin-section after intra-anal air insufflation.Then the data were 3D reconstructed simulating in virtual endoscopy and the results were compared with what seen with the conventional colonoscopy and the clinic pathological findings.Results A total of 21 polyps in 12 patients were discovered by colonoscopy,while 15 polyps in 10 patients by CTVC.In addition,29 cases of colorectal cancer were diagnosed by colonoscopy,and 27 cases of colorectal cancer were discovered by CTVC.Besides,two cases of liver metastasis and one case of lymph node metastasis in posterior peritoneal cavity were demonstrated in colonic cancer by CTVC.Conclusion CTVC is a non-invasive and valid technique for colonic occupying lesion,which can demonstrate not only the location and the size of colorectal neoplasms,but also the invasive depth and extracolonic metastasis.CTVC has an important value in clinical stage and choice of surgery for colorectal cancer.

Experimental study of tagged fluid in CT virtual colonoscopy / 第三军医大学学报

Objective To investigate the effects of tagged fluid and substraction in CT virtual colonoscopy (CTVC) on the conspicuity of polyps and to confirm the optimal attenuation value and the optimal viewing window. Methods Polyps measured 3-10 mm were created in fresh porcine colon in vitro and submerged in saline and mixed with positive contrast medium for the CT values of 200 HU, 400 Hu, 600 HU, and 800 HU. Polyps were measured before and after substraction and compared with those in the control group. The effects of different viewing windows and different attenuation values on the measurement and conspicuity of polyps were analyzed. Results The optimal attenuation value of tagged fluid was 800 HU and the optimal viewing window was colon (-150 HU, 1 500 HU) and bone (500 HU, 2 500 HU). Conclusion The combination of tagged fluid and CT substraction can improve the conspicuity of small polyps covered by colonic fluid.

Clinical Application of 64-slice Spiral CT Colonography / 实用放射学杂志

Objective To evaluate the techniques and application of 64-slice helical CT colonography in colonic lesions. Methods Thirty-eight patients (including 12 colonic carcinomas,10 polypi, 9 colon multiple scrobiculus, 2 multiple diverticula, 2 negative, 1 congenital bowel malrotaion,1 ulcerative colitis and tunica mucosa glandular organ hyperplasy,1 colocolic anastomosis of terminal ileum and sigmoid colon) underwent volume scanning using 64-slice helical CT after cleaning colon. Six types of reconstruction including CT virtual colonoscopy(CTVC), volume rendering(VR), multiple planar reconstruction(MPR), 360?sectional view, RaySum,and navigation were gained.CTVC appearances were compared with that of conventional colonoscopy(CC).Results In 12 colonic carcinomas and 10 polypi,the lesions’ morphology,number,size, were satisfactorily shown by CTVC. The lesions’ location,range,and 1 intestinal canal obviously stenosis were also exactly shown by RaySum.The relationship between tumor and environment, 3 liver or retroperitoneal lymph node metastasis were satisfactorily shown by MPR and 2D transection image. On 360?sectional view,the distance between tumor and anus was exactly measured and the result was in conformity to that of CC. Of the CTVC appearances,1 sigmoid carcinoma and 1 transverse colon polyp was in unconformity to that of CC;1 ulcerative colitis and descending colon carcinoma was diagnosed as ulcerative colitis and tunica mucosa glandular organ hyperplasy by pathology.Conclusion 64-slice helical CT is a valuable imaging technique for detecting colon diseases. CTVC can obtain more clinical information than CC combining MPR,RaySum and VR.