Current status on performance of CT colonography and clinical indications

Role of CT in the Staging of Colorectal Tumors: A Preliminary Study on 10 Dogs

This study aimed to define the CT features of colorectal tumors in dogs and assess CT's role in tumor staging. It was a retrospective, multicenter, descriptive study involving dogs with a cyto-histopathological diagnosis of colorectal tumors and high-quality pre- and post-contrast CT scans of the abdomen. CT successfully identified colorectal lesions in all cases, showing variations such as wall thickening, presence of masses, and luminal stenosis. It also detected lymph node involvement. Overall, this study helps us to understand the CT features of both epithelial and mesenchymal colorectal tumors, emphasizing CT's importance in staging and surgical planning for affected dogs. Larger studies are needed to identify specific CT findings for different colorectal neoplasms.

CT colonography: can we achieve an adequate bowel preparation without diet restriction?

OBJECTIVE

To evaluate if an adequate bowel preparation for CT colonography, can be achieved without diet restriction, using a reduced amount of cathartic agent and fecal tagging. To investigate the influence of patients' characteristics on bowel preparation and the impact on patients' compliance.

METHODS

In total, 1446 outpatients scheduled for elective CT colonography were prospectively enrolled. All patients had the same bowel preparation based on a reduced amount of cathartic agent (120 g of macrogol in 1.5 l of water) the day before the exam and a fecal tagging agent (60 ml of hyperosmolar oral iodinated agent) the day of the exam. No dietary restrictions were imposed before the exam. The bowel preparation was evaluated using a qualitative and quantitative score. Patients were grouped by age, gender, and presence of diverticula in both scores. Patients' compliance has been evaluated with a questionnaire after the end of the exam and with a phone-calling interview the day after the exam.

RESULTS

According to the qualitative score, adequate bowel preparation was achieved in 1349 patients (93.29%) and no statistical differences were observed among the subgroups of patients. Quantitative scores demonstrated that colon distension was significantly better in younger patients and without diverticula. A good patients' compliance was observed and most patients (96.5%) were willing to repeat it.

CONCLUSIONS

The lack of diet restriction does not affect the quality of CTC preparation and good patient's compliance could potentially increase the participation rate in CRC screening programs.

KEY POINTS

• An adequate quality bowel preparation for CT colonography can be achieved without diet restriction, using a reduced amount of cathartic agent (120 g of macrogol in 1.5 l of water) and fecal tagging (60 ml of hyperosmolar oral iodinated agent). • A bowel preparation based on the combination of a reduced amount of cathartic agent and fecal tagging, without diet restriction, allows obtaining good quality in more than 90% of patients. • The bowel preparation scheme proposed reduces the distress and discomfort experienced by the patients improving adherence to CTC.

Low-volume reduced bowel preparation regimen for CT colonography: a randomized noninferiority trial

PURPOSE

To determine whether the quality of a low-volume reduced bowel preparation (LV-RBP) for CT Colonography (CTC) is noninferior to full-volume reduced bowel preparation (FV-RBP) regimen.

METHODS

In this randomized controlled trial, consecutive participants referred for CTC were randomly assigned to receive LV-RBP (52.5 g of PMF104 in 500 mL of water) or FV-RBP (105 g of PMF104 in 1000 mL of water). Images were independently reviewed by five blinded readers who rated the quality of bowel preparation from 0 (best score) to 3 (worst score). The primary outcome was the noninferiority of LV-RBP to FV-RBP in the proportion of colonic segments scored 0 for cleansing quality, with noninferiority margin of 10%. Volume of residual fluids, colonic distension, lesions and polyps detection rates and patient tolerability were secondary outcomes.

RESULTS

From March 2019 to January 2020, 110 participants (mean age 65 years ± 14 [standard deviation]; 74 women) were allocated to LV-RBP (n = 55) or FV-RBP (n = 55) arms. There were 92% segment scored 0 in colon cleansing quality in LV-RBP and 94% in FV-RBP for prone scans, and 94% vs 92% for supine scans. Risk difference was - 2.1 (95% CI -5.9 to 1.7) and 1.5 (95% CI -2.4 to 5.4) for prone and supine positions, respectively. Residual fluids and colonic distension were also noninferior in LV-RBP. LV-RBP was associated with a lower number of evacuations during preparation (7 ± 5 vs 10 ± 6, p = 0.002).

CONCLUSION

The LV-RBP for CTC demonstrated noninferior quality of colon cleansing with improved gastrointestinal tolerability compared to FV-RBP regimen.

Prevalence of polyps ≥6 mm on follow-up CT colonography in a cohort with no significant colon polyps at baseline

AIM

Assess the prevalence of neoplasia ≥6 mm at repeat CT colonoscopy (CTC) in individuals with no significant lesions at baseline.

METHODS

Individuals aged ≥18 years, with/without CRC risk factors, with no polyps ≥6 mm on baseline CTC (negative baseline) who underwent repeat CTC in a large HMO from 2001 to 2011 were retrospectively identified. Studies were reviewed by board-certified radiologists with experience interpreting CTC. Demographic details, CRC risk factors, and the number, size, and location of incident lesions were noted. Findings were classified using the C-RADS scale. Lesion prevalence at CTC-2 was determined, and study interval and risk characteristics of patients with- and without findings were compared.

RESULTS

Our study included 636 individuals (369 men [58.0%]; mean age 59.9 years) with negative baseline CTC who underwent repeat CTC after a mean 4.6 year interval (SD 1.6 years). At baseline, 469/636 (73.7%) were at average risk for CRC; 418 remained at average risk for CTC-2 with 51 (8.0%) developing new risk factors in the interval between studies. At CTC-2, 47 participants (7.4%) presented 52 significant neoplasia: 35 polyps 6-9 mm, 14 polyps ≥10 mm, and 3 masses in 3/636 participants (0.47%). 2/3 masses, 6/14 polyps ≥10 mm (42.9%), and 12/25 polyps 6-9 mm (48.0%) were in individuals with risk factors for CRC. Histopathology was available for 12/52 lesions (23.1%): 8 tubular adenomas, 2 villous adenomas, 1 hamartomatous polyp, 1 case of normal tissue.

CONCLUSION

A mean 4.6 years after negative-baseline CTC, neoplasia ≥6 mm were seen in 7.4% of participants, including masses in 0.47%, supporting recommendations for a 5-year study interval.

Weight-adapted iodinated contrast media administration in abdomino-pelvic CT: Can image quality be maintained?

INTRODUCTION

In many centres, a fixed method of contrast-media administration is used for CT regardless of patient body habitus. The aim of this trial was to assess contrast enhancement of the aorta, portal vein, liver and spleen during abdomino-pelvic CT imaging using a weight-adapted contrast media protocol compared to the current fixed dose method.

METHODS

Thirty-nine oncology patients, who had previously undergone CT abdomino-pelvic imaging at the institution using a fixed contrast media dose, were prospectively imaged using a weight-adapted contrast media dose (1.4 ml/kg). The two sets of images were assessed for contrast enhancement levels (HU) at locations in the liver, aorta, portal vein and spleen during portal-venous enhancement phase. The t-test was used to compare the difference in results using a non-inferiority margin of 10 HU.

RESULTS

When the contrast dose was tailored to patient weight, contrast enhancement levels were shown to be non-inferior to the fixed dose method (liver p < 0.001; portal vein p = 0.003; aorta p = 0.001; spleen p = 0.001). As a group, patients received a total contrast dose reduction of 165 ml using the weight-adapted method compared to the fixed dose method, with a mean cost per patient of £6.81 and £7.19 respectively.

CONCLUSION

Using a weight-adapted method of contrast media administration was shown to be non-inferior to a fixed dose method of contrast media administration. Patients weighing 76 kg, or less, received a lower contrast dose which may have associated cost savings. A weight-adapted contrast media protocol should be implemented for portal-venous phase abdomino-pelvic CT for oncology patients with adequate renal function (>70 ml/min/1.73 m²).

Assessment of 3 Bowel Preparation Protocols for Computed Tomography Pneumocolonography in Normal Dogs

OBJECTIVE

To investigate the effects of 3 different bowel preparation protocols on interpretation of computed tomography (CT) pneumocolonography images.

STUDY DESIGN

Experimental crossover design.

ANIMALS

Intact male, hound-cross, research colony dogs (n=4).

METHODS

All dogs received the 3 different bowel preparation protocols for CT pneumocolonography in the same order, with a minimum of 2 weeks between protocols. For each segment of large bowel, the subjective adequacy of bowel cleansing was assessed, residual fecal and bowel volumes were calculated, and the density of fecal material in the bowel lumen was measured. Linear mixed effect models that included a random dog effect were used to evaluate mean differences in outcome measures across protocols.

RESULTS

No dogs experienced any clinical problems associated with the protocols or CT pneumocolonography. Bowel cleansing was considered adequate for CT pneumocolonography interpretation for all 3 protocols. There was a significant effect of protocol on residual fecal volumes and the fecal:bowel volume ratio, with the 2 protocols that included an extended fast producing the lowest total residual fecal volumes. There was a significant effect of protocol on maximum measured density of residual fecal material with the 2 protocols including iodinated contrast having the highest density.

CONCLUSIONS

All protocols were sufficient for CT pneumocolonography interpretation and contrast-tagging of residual fecal material was successful with oral iopamidol administration. An at-home bowel cleansing protocol may provide adequate bowel cleansing for CT pneumocolonography image interpretation.

Prevalence and distribution of colonic diverticula assessed with CT colonography (CTC)

OBJECTIVES

This study aimed to evaluate the prevalence of colonic diverticula according to age, gender, distribution, disease extension and symptoms with CT colonography (CTC).

METHODS

The study population included 1091 consecutive patients who underwent CTC. Patients with diverticula were retrospectively stratified according to age, gender, clinical symptoms and colonic segment involvement. Extension of colonic diverticula was evaluated using a three-point quantitative scale. Using this data, a multivariate regression analysis was applied to investigate the existence of any correlation among variables.

RESULTS

Colonic diverticula were observed in 561 patients (240 men, mean age 68 ± 12 years). Symptomatic uncomplicated diverticular disease (SUDD) was present in 47.4% of cases. In 25.6% of patients ≤40 years, at least one diverticulum in the colon was observed. Prevalence of right-sided diverticula in patients >60 years was 14.2% in caecum and 18.5% in ascending colon. No significant difference was found between symptomatic and asymptomatic patients regarding diverticula prevalence and extension. No correlation was present between diverticula extension and symptoms.

CONCLUSION

The incidence of colonic diverticula appears to be greater than expected. Right colon diverticula do not appear to be an uncommon finding, with their prevalence increasing with patient age. SUDD does not seem to be related to diverticula distribution and extension.

KEY POINTS

Incidence of colonic diverticula appears to be greater than expected. Right colon diverticula do not appear to be an uncommon finding. SUDD does not seem to be related to diverticula distribution and extension.

Role of CT Colonography in Colonic Lesions and Its Correlation with Conventional Colonoscopic Findings

BACKGROUND

Preoperative evaluation in patients with colorectal carcinoma is essential for a correct therapeutic plan. Conventional colonoscopy has certain limitations including its inability to detect synchronous lesions in case of distal obstructive mass and inaccurate tumour localization. CT colonography combines cross sectional imaging with virtual colonoscopic images and offers a comprehensive preoperative evaluation in patients with colorectal carcinoma including detection of synchronous lesions with accurate segmental localization and loco regional staging.

AIM

The objective was to determine the role of CT colonography in various colonic lesions and to correlate the findings with conventional colonoscopy and histopathological findings.

SETTINGS AND DESIGN

This prospective study included 50 patients with clinical symptoms suspicious of colonic pathology.

MATERIALS AND METHODS

All the patients underwent both CT colonography and conventional colonoscopy on the same day. CT colonography was performed in supine and prone position. Considering histopathological and/or surgical findings as gold standard, sensitivity and specificity of both the modalities were calculated.

RESULTS

Conventional colonoscopy missed two synchronous lesions proximal to occlusive mass and one lesion proximal to the anastomotic site; all were detected with CT colonography. One carpet lesion in rectum and one case of mild ulcerative colitis were missed by CT colonography. Sensitivity and specificity for detection of colorectal cancer were 97.56% and 100%, resp. with PPV and NPV of 100% and 93.75%, for CT colonography and 92.68% and 100%, respectively with PPV and NPV of 100% and 83.3% for conventional colonoscopy. Sensitivity for correct detection of acute and chronic ulcerative colitis of CT colonography was 66.6 % and 100 %, resp.

CONCLUSION

CT colonography has higher sensitivity than conventional colonoscopy for detection of colorectal carcinoma, including its ability to detect abnormalities proximal to obstructing lesion, accurate segmental localization of lesions and staging. However, some limitations of CT colonography were difficulty in detection of flat lesions and lack of information about hyperemia and superficial mucosal erosion, where conventional colonoscopy scored over CT colonography.

Colon capsule endoscopy

Colon capsule endoscopy (CCE) is a minimally invasive technique specifically designed to explore the colon without sedation and air insufflation. CCE may overcome some of the limitations of colonoscopy. Second-generation CCE (CCE-2) was proved accurate in detecting colonic neoplastic lesions when used in average-risk individuals. The evidence to date supports the use of CCE-2 in cases of colonoscopy failure, in patients unwilling to undergo colonoscopy, and when colonoscopy is contraindicated. Other potential applications, such as colorectal cancer screening or diagnostic surveillance of inflammatory bowel disease, require clarification.

Colon capsule versus CT colonography in patients with incomplete colonoscopy: a prospective, comparative trial

OBJECTIVE

In case of incomplete colonoscopy, several radiologic methods have traditionally been used, but more recently, capsule endoscopy was also shown to be accurate. Aim of this study was to compare colon capsule endoscopy (CCE) and CT colonography (CTC) in a prospective cohort of patients with incomplete colonoscopy.

DESIGN

Consecutive patients with a previous incomplete colonoscopy underwent CCE and CTC followed by colonoscopy in case of positive findings on either test (polyps/mass lesions ≥6 mm). Clinical follow-up was performed in the other cases to rule out missed cancer. CTC was performed after colon capsule excretion or 10-12 h postingestion. Since the gold standard colonoscopy was performed only in positive cases, diagnostic yield and positive predictive values of CCE and CTC were used as study end-points.

RESULTS

100 patients were enrolled. CCE and CTC were able to achieve complete colonic evaluation in 98% of cases. In a per-patient analysis for polyps ≥6 mm, CCE detected 24 patients (24.5%) and CTC 12 patients (12.2%). The relative sensitivity of CCE compared to CTC was 2.0 (95% CI 1.34 to 2.98), indicating a significant increase in sensitivity for lesions ≥6 mm. Of larger polyps (≥10 mm), these values were 5.1% for CCE and 3.1% for CTC (relative sensitivity: 1.67 (95% CI 0.69 to 4.00)). Positive predictive values for polyps ≥6 mm and ≥10 mm were 96% and 85.7%, and 83.3% and 100% for CCE and CTC, respectively. No missed cancer occurred at clinical follow-up of a mean of 20 months.

CONCLUSIONS

CCE and CTC were of comparable efficacy in completing colon evaluation after incomplete colonoscopy; the overall diagnostic yield of colon capsule was superior to CTC.

TRIAL REGISTRATION NUMBER

NCT01525940.

Computed tomographic pneumocolonography in normal dogs

Objectives of this prospective study were to describe effects of varying technical components that may contribute to an optimal protocol for computed tomographic pneumocolonography (CTP) in dogs, and to develop a standardized methodology for CTP as a future potential diagnostic tool in canine clinical patients with large bowel disease. Eight purpose-bred intact male hound cross-research dogs were enrolled and randomized to groups based on variables of pressure/body position (n = 4) and insufflation time (n = 4). For each segment of large bowel (rectum, colorectal junction, descending colon, transverse colon, ascending colon), the adequacy of bowel preparation, % of bowel lumen filled with fecal material, and bowel tortuosity or folding were assessed. Measurements of bowel wall thickness (cm), cross-sectional bowel lumen diameter (cm), and cross-sectional bowel luminal area (cm(2) ) were obtained at standardized locations within the large bowel. False discovery rates (FDR) were calculated to adjust for multiple testing. Values of FDR < 0.05 were considered significant. Differences in mean cross-sectional area and diameter and bowel wall thickness under increasing pressure were not significant after adjusting for multiple testing; some had raw p values <0.05. Ascending colon diameter and ascending colon area significantly increased with insufflation time (FDR < 0.05). No other response variables showed a significant change with insufflation time. The optimal insufflation pressure for maintaining pneumocolon in this study was determined to be 20 mmHg. CTP is a feasible technique to provide consistent distension for imaging of the large bowel and further study on application of CTP in clinical patients is warranted.

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 tomography colonography service at a university hospital that primarily assists patients from the public health system, with high accuracy, good acceptance and effective radiation doses. Our results seem to be comparable to other centers of excellence and fall within acceptable published guidelines, showing that a successful computed tomography colonography program can be reproduced in a South American population screened in a university hospital.

Computed tomography of the bowel: a prospective comparison study between four techniques

OBJECTIVES

The major objective was to prospectively compare the grade of bowel distension obtained with four different computed tomography (CT) techniques dedicated for the examination of the small intestine (CT enteroclysis [CTE] and enterography [CTe]), of the colon (CT with water enema [CT-WE]), or both (CTe with water enema [CTe-WE]). The secondary objective was to assess patients' tolerance toward each CT protocol.

MATERIALS AND METHODS

Recruitment was designed to obtain four groups of the same number of patients (30). Each group corresponded to a specific CT technique, for a total of 120 consecutive outpatients (65 male and 55 female, mean age 51.09 ± 13.36 years). CTE was performed after injection of methylcellulose through a nasojejunal tube, while in the CTe protocol a polyethylene glycol electrolyte solution was orally administered to patients prior to the CT acquisition. In the CT-WE protocol intraluminal contrast (water) was administered only by a rectal enema, while CTe-WE technique included both a rectal water enema and oral ingestion of neutral contrast material to obtain a simultaneous distension of small and large bowel. CT studies were reviewed in consensus by two gastrointestinal radiologists who performed a quantitative and qualitative analysis of bowel distension on a per segment basis. The presence and type of adverse effects were recorded.

RESULTS

CTE provided the best distension of jejunal loops (median diameter 27 mm, range 17-32 mm) when compared to all the other techniques (p<0.0001). The frequency of patients with an adequate distension of the terminal ileum was not significantly different among the four groups (p=0.0608). At both quantitative and qualitative analysis CT-WE and CTe-WE determined a greater and more consistent luminal filling of the large intestine than that provided by both CTE and CTe (p<0.0001 for all colonic segments). Adverse effects were more frequent in patients belonging to the CTE group (p<0.0028).

CONCLUSIONS

CTE allows an optimal distension of jejunal loops, but it is the most uncomfortable CT protocol. When performing CT-WE, an adequate retrograde distension of the terminal ileum was provided in a particularly high percentage of patients. CTe-WE provides a simultaneous optimal distension of both small and large bowel.