Laterally spreading tumors:Limitations of computed tomography colonography

AIM: To prospectively investigate the detection rate of laterally spreading tumors (LSTs) of the colorectum by computed tomography (CT) colonography (CTC).

Single-center study comparing computed tomography colonography with conventional colonoscopy

AIM:To compare the results from computed tomography (CT) colonography with conventional colonoscopy in symptomatic patients referred for colonoscopy. METHODS: The study included 227 adult outpatients, mean age 60 years, with appropriate indications for colonoscopy. CT colonography and colonoscopy were performed on the same day in a metropolitan teaching hospital. Colonoscopists were initially blinded to the results of CT colonography but there was segmental unblinding during the procedure. The primary outcome measures were the sensitivity and specificity of CT colonography for the identification of polyps seen at colonoscopy (i.e. analysis by polyp). Secondary outcome measures included an analysis by patient, extracolonic findings at CT colonography, adverse events with both procedures and patient acceptance and preference. RESULTS: Twenty-five patients (11%) were excluded from the analysis because of incomplete colonoscopy or poor bowel preparation that affected either CT colonography, colonoscopy or both procedures. Polyps and masses (usually cancers) were detected at colonoscopy and CT colonography in 35% and 42% of patients, respectively. Of nine patients with a finaldiagnosis of cancer, eight (89%) were identified by CT colonography as masses (5) or polyps (3). For polyps analyzed according to polyp, the overall sensitivity of CT colonography was 50% (95% CI, 39%-61%) but this increased to 71% (95% CI, 52%-85%) for polyps ≥ 6 mm in size. Similarly, specificity for all polyps was 48% (95% CI, 39%-58%) increasing to 67% (95% CI, 56%-76%) for polyps ≥ 6 mm. Adverse events were uncommon but included one colonic perforation at colonoscopy. Patient acceptance was high for both procedures but preference favoured CT colonography. CONCLUSION: Although CT colonography was more sensitive in this study than in some previous studies, the procedure is not yet sensitive enough for widespread application in symptomatic patients.

Does training and experience influence the accuracy of computed tomography colonography interpretation?

AIM: To evaluate the effect of experience on the accuracy rate of computed tomography colonography (CTC) interpretation and patient preferences/satisfaction for CTC and colonoscopy.

Recent trends in the prevalence and distribution of colonic diverticula in Japan evaluated using computed tomography colonography

BACKGROUND Computed tomography colonography(CTC)may be superior to colonoscopy and barium enema for detecting diverticula.However,few studies have used CTC to diagnose diverticula.AIM To evaluate the current prevalence and distribution of colonic diverticula in Japan using CTC.METHODS This study was conducted as part of the Japanese National Computed Tomographic Colonography Trial,which included 1181 participants from 14 hospitals in Japan.We analyzed the prevalence and distribution of colonic diverticula and their relationships with age and sex.The relationship between the diverticula and the length of the large intestine was also analyzed.RESULTS Diverticulosis was present in 48.1%of the participants.The prevalence of diverticulosis was higher in the older participants(P<0.001 for trend).The diverticula seen in younger participants were predominantly located in the right-sided colon.Older participants had a higher frequency of bilateral type(located in the rightand left-sided colon)diverticulosis(P<0.001 for trend).The length of the large intestine with multiple diverticula in the sigmoid colon was significantly shorter in those without diverticula(P<0.001).CONCLUSION The prevalence of colonic diverticulosis in Japan is higher than that previously reported.The prevalence was higher,and the distribution tended to be bilateral in older participants.

Irritable bowel syndrome evaluation using computed tomography colonography

AIM To evaluate the morphology of the colon in patients with irritable bowel syndrome(IBS) by using computed tomography colonography(CTC).METHODS Twelve patients with diarrhea type IBS(IBS-D), 13 patients with constipation type IBS(IBS-C), 12 patients with functional constipation(FC) and 14 control patients underwent colonoscopy following CTC. The lengths of the rectosigmoid colon, transverse colon and the total colon were measured. The diameters of the rectum, sigmoid colon, descending colon, transverse colon, and ascending colon were measured.RESULTS The mean length of the total colon was 156.5 cm in group C, 158.9 cm in group IBS-D, 172.0 cm in group IBS-C, and 188.8 cm in group FC. The total colon in group FC was significantly longer than that in group C(P < 0.05). The mean length of the rectosigmoid colon was 56.2 cm, 55.9 cm, 63.6cm, and 77.4 cm(NS). The mean length of the transverse colon was 49.9 cm, 43.1 cm, 57.0 cm, and 55.0 cm. The transverse colonin group IBS-D was significantly shorter than that in group IBS-C(P < 0.01) and that in group FC(P = 0.02). The mean diameter of the sigmoid colon was 4.0 cm, 3.3 cm, 4.2 cm, and 4.3 cm(NS). The mean diameter of the descending colon was 3.6 cm, 3.1 cm, 3.8 cm, and 4.3 cm. The descending colon diameter in group IBS-D was significantly less than that in group IBS-C(P = 0.03) and that in group FC(P < 0.001). The descending colon diameter in group FC was significantly greater than that in group C(P = 0.04). The mean diameter of the transverse colon was 4.4 cm, 3.3 cm, 4.2 cm, and 5.0 cm(NS).CONCLUSION CT colonography might contribute the clarification of subtypes of IBS.

Computed tomography colonography and radiation risk:How low can we go?

Computed tomography colonography(CTC)has become a key examination in detecting colonic polyps and colorectal carcinoma(CRC).It is particularly useful after incomplete optical colonoscopy(OC)for patients with sedation risks and patients anxious about the risks or potential discomfort associated with OC.CTC's main advantages compared with OC are its non-invasive nature,better patient compliance,and the ability to assess the extracolonic disease.Despite these advantages,ionizing radiation remains the most significant burden of CTC.This opinion review comprehensively addresses the radiation risk of CTC,incorporating imaging technology refinements such as automatic tube current modulation,filtered back projections,lowering the tube voltage,and iterative reconstructions as tools for optimizing low and ultra-low dose protocols of CTC.Future perspectives arise from integrating artificial intelligence in computed tomography machines for the screening of CRC.

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 scientif ic 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 insuff icient 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.

Preoperative evaluation of colorectal cancer using CT colonography, MRI, and PET/CT

Imaging studies are a major component in the evaluation of patients for the screening,staging and surveillance of colorectal cancer.This review presents commonly encountered findings in the diagnosis and staging of patients with colorectal cancer using computed tomography(CT)colonography,magnetic resonance imaging(MRI),and positron emission tomography(PET)/CT colonography.CT colonography provides important information for the preoperative assessment of T staging.Wall deformities are associated with muscular or subserosal invasion.Lymph node metastases from colorectal cancer often present with calcifications.CT is superior to detect calcified metastases.Three-dimensional CT to image the vascular anatomy facilitates laparoscopic surgery.T staging of rectal cancer by MRI is an established modality because MRI can diagnose rectal wall laminar structure.N staging in patients with colorectal cancer is still challenging using any imaging modality.MRI is more accurate than CT for the evaluation of liver metastases.PET/CT colonography isvaluable in the evaluation of extra-colonic and hepatic disease.PET/CT colonography is useful for obstructing colorectal cancers that cannot be traversed colonoscopically.PET/CT colonography is able to localize synchronous colon cancers proximal to the obstruction precisely.However,there is no definite evidence to support the routine clinical use of PET/CT colonography.

Role of preoperative CT colonography in patients with colorectal cancer

In patients with colorectal cancer (CRC), accurate preoperative evaluation is essential for a correct therapeutic plan. Colonoscopy and intravenous contrast-enhanced computed tomography (CT) are currently recommended in the preoperative work-up for CRC. Preoperative colonoscopy has some limitations such as misdiagnosis of synchronous cancers in cases of incomplete exploration of the colon and inaccurate tumor localization. Intravenous contrast-enhanced CT successfully documents distant metastases although it sometimes enables unsatisfactory locoregional staging. Computed tomography colonography (CTC) is obtained after gas insufflation of the colon and offers a comprehensive preoperative evaluation in patients with CRC, including a definition of the segmental location of the tumor, presence of synchronous lesions or lack thereof, and fairly accurate locoregional staging. CTC has some limitations, including a lack of biopsy capability, suboptimal sensitivity for synchronous small polyps, and unsatisfactory nodal staging. Bearing in mind these limitations, CTC could be employed as a &#x0201c;one-stop-shop&#x0201d; examination for preoperative assessment in patients with CRC.

CT colonography after incomplete colonoscopy in subjects with positive faecal occult blood test

AIM： To report our experience with computed tomography colonography （CTC） systematically performed in subjects with positive faecal occult blood test （FOBT） and an incomplete colonoscopy in the setting of a population-based screening for colorectal cancer （CRC）. METHODS： From April 2006 to April 2007, 43 290 individuals （age range 50-70） who adhered to the regional screening program for the prevention of CRC underwent immunochemical FOBT. FOBT was positive in 1882 subjects （4.3%）. 1463 （77.7%） of these subjects underwent colonoscopy, 903 performed in a single center. Of 903 colonoscopies 65 （7.2%） were incomplete. Forty-two of these subjects underwent CTC. CTC was performed with a 16-MDCT scanner after standard bowel prep （polyethyleneglycole） in both supine and prone position. Subjects whose CTC showed polyps or masses were referred to the endoscopist for repeat colonoscopy under sedation or underwent surgery. Perlesion and per-segment positive predictive values （PPV） were calculated. RESULTS： Twenty-one （50%） of 42 CTCs showed polyps or masses. Fifty-five of these subjects underwent a repeat colonoscopy, whereas 2 subjects underwent surgery for colonic masses of indeterminate nature. Four subjects refused further examinations. CTC correctly identified 2 colonic masses and 20 polyps. PPV for masses or polyps greater than 9 mm was of 87.5%. Per-lesion and per-segment PPV were, respectively, 83.3% and 83.3% for polyps greater or equal to 10 mm, and 77.8% and 85.7% for polyps of 6-9 mm. CONCLUSION： In the context of a screening program for CRC based on FOBT, CTC shows high per-segment and per-lesion PPV for colonic masses and polyps greater than 9 mm. Therefore, CTC has the potential to become a useful technique for evaluation of the non visualized part of the colon after incomplete colonoscopy.

Screening of colorectal cancer: Methods and strategies

Colorectal cancer(CRC)has high incidence and mortality rates,and the em-ergence and application of CRC screening have helped us effectively control the occurrence and development of CRC.Currently,common international screening methods include tests based on feces and blood,and examination methods that allow for visualization,such as sigmoidoscopy and colonoscopy.Some methods have been widely used,whereas others such as multi-target stool RNA test are still being explored and developed,and are expected to become front-line screening methods for CRC in the future.The choice of screening method is affected by external conditions and the patients'situation,and the clinician must choose an appropriate strategy according to the actual situation and the patient's wishes.This article introduces various CRC screening methods and analyzes the factors relevant to the screening strategy.

Virtual gastrointestinal colonoscopy in combination with large bowel endoscopy:Clinical application

Although colorectal cancer (CRC) has no longer been the leading cancer killer worldwide for years with the exponential development in computed tomography (CT) or magnetic resonance imaging, and positron emission tomography/CT as well as virtual colonoscopy for early detection, the CRC related mortality is still high. The objective of CRC screening is to reduce the burden of CRC and thereby the morbidity and mortality rates of the disease. It is believed that this goal can be achieved by regularly screening the average-risk population, enabling the detection of cancer at early, curable stages, and polyps before they become cancerous. Large-scale screening with multimodality imaging approaches plays an important role in reaching that goal to detect polyps, Crohn's disease, ulcerative colitis and CRC in early stage. This article reviews kinds of presentative imaging procedures for various screening options and updates detecting, staging and re-staging of CRC patients for determining the optimal therapeutic method and forecasting the risk of CRC recurrence and the overall prognosis. The combination use of virtual colonoscopy and conventional endoscopy, advantages and limitations of these modalities are also discussed. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.

Rare case of fecal impaction caused by a fecalith originating in a large colonic diverticulum: A case report

BACKGROUND Fecal impaction is defined as a large mass of compacted feces in the colon and has the potential to induce a serious medical condition in elderly individuals.Fecal impaction is generally preventable,and early recognition of the typical radiological findings is important for making an early diagnosis.The factors that lead to fecal impaction are usually similar to those causing constipation.Few cases with fecal impaction associated with a diverticulum have been reported.CASE SUMMARY We present the case of a 62-year-old woman who suffered from abdominal pain and vomiting,had a medical history of repeated acute abdomen and was diagnosed with fecal impaction in the descending colon based on X-ray and computed tomography(CT)imaging.After examination by gastrografinenhanced colonography following colonoscopy and CT colonography,the fecalith was suspected to have been produced at the site of a large diverticulum in the transverse colon.The fecalith was surgically resected,and a histological diagnosis of pseudodiverticulum was made.There was no recurrence during 33 mo of follow-up.CONCLUSION This case highlights the importance of accurate identification and treatment of a fecal impaction.This case indicated that the endoscopic evacuation and subsequent colonography were effective for identifying a diverticulum that might have caused fecal impaction.A fecal impaction was associated with the diverticulum.Consequently,the planned diverticulectomy was performed.Appropriate emergency medical treatment and maintenance treatments should be selected in such cases to prevent recurrence.