Inclusion of computed tomographic colonography on pre-operative CT for patients with colorectal cancer

Radiologic T staging of colon cancer: renewed interest for clinical practice

Radiologic imaging, especially MRI, has long been the mainstay for rectal cancer staging and patient selection for neoadjuvant therapy prior to surgical resection. In contrast, colonoscopy and CT have been the standard for colon cancer diagnosis and metastasis staging with T and N staging often performed at the time of surgical resection. With recent clinical trials exploring the expansion of the use of neoadjuvant therapy beyond the anorectum to the remainder of the colon, the current and future state of colon cancer treatment is evolving with a renewed interest in evaluating the role radiology may play in the primary T staging of colon cancer. The performance of CT, CT colonography, MRI, and FDG PET-CT for colon cancer staging will be reviewed. N staging will also be briefly discussed. It is expected that accurate radiologic T staging will significantly impact future clinical decisions regarding the neoadjuvant versus surgical management of colon cancer.

Diagnostic accuracy of ≥ 16-slice spiral computed tomography for local staging of colon cancer: A systematic review and meta-analysis

BACKGROUND

Colorectal cancer is one of the most common cancers worldwide with high mortality and is classified as a single entity, although colon cancer and rectal cancer have largely different diagnoses, treatments, surgical methods, and recurrence rates. ≥ 16-slice spiral computed tomography (SCT) is mostly applied to detect the local stage of colon cancer; however, its diagnostic accuracy and whether it is conducive to distinguishing between high-risk and low-risk colon cancer are unclear.

AIM

To systematically review the diagnostic accuracy of ≥ 16-slice SCT for local staging of colon cancer.

METHODS

Based on the PubMed, EMBASE, Cochrane Library, and Web of Science databases, computers were used to search the literature from the establishment of the database to April 2021, and the results of the diagnostic tests on ≥ 16-slice SCT for local staging of colon cancer were collected according to the inclusion criteria. The data were then extracted and assessed on the basis of the Quality Assessment Checklist of the Institute of Economics of Canada, Reference Citation Analysis (https://www.referencecitationanalysis.com/). Afterward, a meta-analysis was performed using the statistical software Meta-disc 14.0 and Stata 15.0.

RESULTS

Eleven studies that provided data on 1613 subjects with computed tomography diagnostic tests were included in this study. Meta-analysis revealed that the pooled sensitivity, pooled specificity, pooled negative likelihood ratio (LR), pooled diagnostic odds ratio, and area under the fitted receiver operating characteristic (ROC) curve of ≥ 16-slice SCT for colon cancer T staging were 0.67 (95%CI: 0.65-0.70), 0.81 (95%CI: 0.80-0.83), 4.13 (95%CI: 2.66-6.41), 0.39 (95%CI: 0.31-0.49), 10.81 (95%CI: 7.33-15.94), and 0.829, respectively, while the specificity, negative LR, diagnostic odds ratio, and area under the fitted ROC curve of ≥ 16-slice SCT for N staging of colon cancer were 0.54 (95%CI: 0.49-0.59), 0.74 (95%CI: 0.70-0.77), 1.92 (95%CI: 1.36-2.70), 0.67 (95%CI: 0.51-0.87), 3.74 (95%CI: 1.76-7.94), and 0.829 respectively. The sensitivity and specificity of ≥ 16-slice SCT for colon cancer T staging were acceptable, while the sensitivity for colon cancer N staging was relatively low, though its specificity was acceptable.

CONCLUSION

≥ 16-slice SCT for local staging of colon cancer has good diagnostic value; however, the accuracy needs to be confirmed by further clinical practice.

ACR Appropriateness Criteria® Staging of Colorectal Cancer: 2021 Update

Preoperative imaging of rectal carcinoma involves accurate assessment of the primary tumor as well as distant metastatic disease. Preoperative imaging of nonrectal colon cancer is most beneficial in identifying distant metastases, regardless of primary T or N stage. Surgical treatment remains the definitive treatment for colon cancer, while organ-sparing approach may be considered in some rectal cancer patients based on imaging obtained before and after neoadjuvant treatment. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Pre-colectomy location and TNM staging of colon cancer by the computed tomography colonography: a diagnostic performance study

BACKGROUND

The Chinese Society of Clinical Oncology guidelines 2018 and the recent update of that (version 2020) recommends accurate examination before major treatment for decision(s) in cases of colon cancer. Also, the difficulty in the identification of the lesion during colectomy may lead to resection of a wrong segment of the colon or a more extensive resection than planned. Accurate pre-colectomy local staging of colon cancer is required to make decisions for treatment of colon cancer. The objective of the study was to evaluate the diagnostic performance of the computed tomography colonography (CTC) for pre-colectomy tumor location and tumor, node, and metastasis (TNM) staging of colon cancer.

METHODS

Data of preoperative colonoscopies, CTC, surgeries, and surgical pathology of a total of 269 patients diagnosed with colon cancer by colonoscopy and biopsy and underwent pre-colectomy location and TNM staging by CTC were collected and analyzed. The consistency between the radiological and the surgery/surgical-pathological for location and TN stages of colon tumor were estimated with the weighted kappa or kappa coefficient (κ) at 95% confidence interval (CI).

RESULTS

CTC detected 261 (93%) and colonoscopy detected 201 (72%) correct locations of tumors. Sensitivity and accuracy of CTC for detection of location of colon tumors were 100% and 92.58% (κ = 0.89; 95% Cl: 0.83-0.95). 72.48% sensitivity, 90.64% specificity, and 83.57% accuracy were reported for CTC in differentiation of tumors confined to the colon wall (T1/T2) from advanced tumors (T3/T4) (κ = 0.69, 95% Cl: 0.51-0.75). 81.01% sensitivity, 89.11% specificity, and 83.93% accuracy of CTC was reported for differentiation of tumors between low-intermediate risk and high risk (κ = 0.68, 95% Cl: 0.53-0.75). 69.31% sensitivity, 66.15% specificity, and 67.14% accuracy of CTC were reported for N staging of tumors (κ = 0.41, 95% Cl: 0.59-0.69).

CONCLUSIONS

CTC has high diagnostic parameters for pre-colectomy location and T staging of colon tumors except patients of colon cancer who received neoadjuvant chemotherapy.

LEVEL OF EVIDENCE

III.

TECHNICAL EFFICACY STAGE

2.

Assessment of the Clinical Usefulness of Preoperative Computed Tomography in Colorectal Cancer Patients Who Received Unplanned Reoperation

Background

In the unplanned reoperation of colorectal cancer patients, computed tomography (CT) is increasingly utilized to locate postoperative complications and previously unlocalized lesions. The purpose of this study is to explore the application of CT in the mortality and complications of the reoperation of colorectal cancer. Patients and Methods. We performed a retrospective review of collected data from the colorectal surgeries of 90 identified colorectal cancer patients who received an unplanned reoperation from 2010 to 2018. Patients were stratified according to those with preoperative CT imaging (CT group, n = 36) and those without preoperative CT imaging (NCT group, n = 54). Twenty-four statistical indicators of each patient were studied, including their preoperative risk, surgical characteristics, and postoperative outcomes, and satisfaction was evaluated. All data were statistically analysed for predicting postoperative complications by univariate and multivariate logistic regression analyses.

Results

Ninety patients received an unplanned reoperation in the study, and 40% (36/90) of these patients underwent preoperative CT examination. Patients' risk factors were similar between CT and NCT groups. Preoperative imaging was more commonly performed for reoperative new anastomosis + ileostomy but less common for reoperative Dixon's procedure. The operative duration of the NCT group was longer (139 vs. 104 min, respectively, P = 0.01). Preoperative NCT examination (OR 1.24; 95% CI = 1.09-1.42; P = 0.01) was an independent predictor of postoperative complications. Importantly, three patients died after an unplanned reoperation for colorectal cancer, which occurred only in the NCT group (5.6% vs. 0.0%, P = 0.01).

Conclusion

The use of conventional preoperative CT optimizes the choice of the surgical site and the strategy of laparotomy, so as to reduce the length of operation. Preoperative imaging evaluation should be performed for patients undergoing repeat abdominal surgery.

Preoperative CT Colonography in Partially Obstructed Colon Cancer, and its Benefit in Surgical Management

Background and aims

Stenotic colorectal carcinoma impending obstruction (SCRCIO) is a frequently encountered situation complicating 10% to 19% of colorectal cancers. This group of patients cannot undergo complete colonoscopic assessment. The aim of this study is to examine the accuracy of computed tomographic colonography (CTC) as preoperative assessment of the colon of patients with SCRCIO and to measure the effect on the surgical decision.

Materials and methods

This was a prospective study, from September 2009 through December 2012, on a cohort of symptomatic adult patients with SCRCIO. Patients underwent CTC evaluation after failed conventional colonoscopy (CC), followed by a follow-up endoscopic examination 3–6 months after surgical treatment.

Results

Twenty-nine patients with an average age of 55 were included in this study; the majority of stenotic masses were located in the sigmoid colon. Preoperative CTC matched the colonoscopy location of the stenotic masses (17 patients). CTC sensitivity per stenotic lesion detection was 100% and 92.5% for the location. Sensitivity was 100% for synchronous lesions, and CTC changed surgical plan in 17% of the patients.

Conclusion

CTC presented high sensitivity, specificity and accuracy for the identification of colonic lesions of any size. Preoperative CTC may possibly become the diagnostic procedure of choice for SCRCIO patients. It enables surgeons to evaluate the entire colon, minimizing the possibility of surgical re-intervention if there is a finding of synchronous neoplastic lesions at postoperative follow-up endoscopy.

Accuracy of CT colonography in the preoperative staging of colon cancer: a prospective study of 217 patients

AIM

The purpose of the present study was to evaluate the accuracy of computed tomography colonography (CTC) in the preoperative localization and TN staging of colon cancer. CTC can be an effective technique for preoperative evaluation of colon cancer and could facilitate the selection of high-risk patients who may benefit from neoadjuvant chemotherapy.

METHOD

This was a prospective observational study conducted at a single tertiary-care centre. It involved 217 patients (225 tumours) who had colon cancer and underwent preoperative CTC and elective colectomy. The radiologist determined the TNM stage using postprocessing software with multiplanar images and virtual colonoscopy. The following criteria were analysed for every colon tumour: location, size and signs of direct colon wall invasion. The histopathological findings of the surgical colectomy specimens served as the reference standard for local staging.

RESULTS

CTC detected all tumours and achieved an exact location in 208 cases (92.4%). CTC findings changed the surgical plan in 31 patients (14.3%) following colonoscopy. The accuracy in differentiating T3/T4 vs T1/T2 tumours was 87.1%, with a sensitivity and specificity of 88.5% and 84.1%, respectively (kappa = 0.71). For high-risk tumours (T3 ≥ 5 mm and T4), CTC showed an accuracy, sensitivity and specificity of 82.7%, 86% and 80%, respectively (kappa = 0.65). The accuracy of N-stage evaluation was 69.3%, the sensitivity 74% and the specificity 67.1% (kappa = 0.37).

CONCLUSION

CTC provides accurate information for the assessment of tumour localization and T staging, allowing better surgical planning and also allows the selection of locally advanced tumours that may benefit from new treatments such as neoadjuvant chemotherapy.

Diagnostic accuracy of computed tomography colonography for tumor depth in colorectal cancer: A systematic review and meta-analysis

BACKGROUND

Accurate preoperative determination of tumor depth is a major concern in colorectal cancer. Assessment of tumor depth can influence the treatment strategy for colorectal cancer, but there is currently no universal diagnostic standard. This review sought to evaluate the diagnostic performance of computed tomography (CT) colonography for tumor infiltration depth in colorectal cancer.

METHODS

The PubMed, Scopus, and Cochrane Central Register of Controlled Trials databases were searched to identify studies that compared the tumor depth using CT colonography with that determined using pathological assessment. Relevant data were extracted from the eligible studies by two review authors working independently. Any disagreement was resolved by discussion. The quality of the studies was assessed using the QUADAS-2 tool. The diagnostic performance of CT colonography for tumor depth in colorectal cancer was evaluated by meta-analysis using sensitivity and specificity values and diagnostic odds ratios.

RESULTS

The systematic literature search identified 16 eligible studies. The pooled sensitivity and specificity values and diagnostic odds ratios were 97.8% (95% confidence interval [CI] 88.1-99.6), 76.4% (95% CI 59.9-87.5), and 142.6 (95% CI 20.0-1071.0) for T2 invasion, 97.7% (95% CI 92.1-99.3), 83.5% (95% CI 75.9-89.0), and 212.1 (95% CI 50.6-888.1) for T3 invasion, and 84.9% (95% CI 61.7-95.1), 97.5% (95% CI 93.2-99.1), and 219.5 (95% CI 37.8-1273.6) for T4 invasion, respectively.

CONCLUSIONS

CT colonography was found to have high diagnostic performance and was useful for determining tumor depth in colorectal cancer.

Do Self-Expanding Metal Stents as a Bridge to Surgery Benefit All Patients with Obstructive Left-Side Colorectal Cancers?

Background

Self-expanding metal stents (SEMS) have been increasingly used in patients with obstructive left-sided colorectal cancer (OLCC); however, stent-specific complications (e.g., perforations) might worsen the long-term survival outcome. Strict indication needed to be identified to confirm the benefit subgroups. This study was designed to explore the indication for emergency surgery (ES) and SEMS in patients with OLCC and to suggest optimal strategies for individuals.

Methods

After propensity score matching, 36 pairs were included. Perioperative and long-term survival outcomes (3-year overall survival (OS) and 3-year disease-free survival (DFS)) were compared between the ES and SEMS groups. Independent risk factors were evaluated among subgroups. Stratification survival analysis was performed to identify subgroups that would benefit from SEMS placement or ES.

Results

The perioperative outcomes were similar between the SEMS and ES groups. The 3-year OS was comparable between the SEMS (73.5%) and ES (60.0%) groups, and the 3-year DFS in the SEMS group (69.7%) was similar to that in the ES group (57.1%). The pT stage was an independent risk factor for 3-year DFS (p = 0.014) and 3-year OS (p = 0.010) in the SEMS group. The comorbidity status (p = 0.049) independently affected 3-year DFS in the ES group. The 3-year OS rate was influenced by the cM stage (p = 0.003). Patients with non-pT4 stages in the SEMS group showed obviously better 3-year OS (95.0%) than the other subgroups. The 3-year OS rate was 36.4% in the ES group when patients had a worse comorbidity status than their counterparts.

Conclusion

SEMS might be preferred for patients of obstructive left-sided colorectal cancer in the "high-operative risk group" with existing comorbidities or those without locally advanced invasion, such as the non-pT4-stage status.

Three-dimensional computed tomographic angiography with computed tomographic colonography for laparoscopic colorectal surgery

PURPOSE

To prospectively correlate the preoperative vessel anatomy in three-dimensional computed tomographic angiography with computed tomographic colonography (3D-CTA with CTC) with that in laparoscopic surgery for colorectal cancer.

METHODS

The study protocol was approved by our institutional review board. The study population consisted of 101 patients with colon cancer who underwent 3D-CTA with CTC between June 2016 and January 2018. Two radiologists assessed the branching patterns of sigmoid arteries (SAs) and right colonic artery (RCA), the position between the ileocolic artery (ICA) and superior mesenteric vein (SMV), and the existence of an accessory middle colonic artery (aMCA). The vessel anatomy on 3D-CTA with CTC was correlated with that of intraoperative findings.

RESULTS

Ninety-eight examinations (97.0%) were technically successful. Between preoperative and intraoperative vessel anatomy, the branching patterns of SAs were concordant in all 29 cases with rectosigmoid and descending colon cancer. The branching patterns of RCA and the position between the ICA and SMV were completely concordant in 32 cases of cecal and ascending colon cancer. No aMCA was identified either intraoperatively or by imaging analysis.

CONCLUSIONS

3D-CTA with CTC guided the surgeons to determine the resection margin of the relevant vessels for laparoscopic colorectal surgery.

Over-diagnosis for preoperative T staging of colorectal cancer - A case series

Introduction

Recent progressive imaging technology such as multiplanar reconstruction on computed tomography (CT) and colonoscopy has made preoperative T staging of colorectal cancer (CRC) more accurate. Nevertheless, it is still difficult to make a correct diagnosis in some cases. The aim of this case study was to investigate the accuracy of T staging diagnosis in patients with CRC who underwent curative operations and to identify the causes of preoperative over-diagnosis.

Method

Medical charts of 1013 colorectal cancer patients who underwent a curative operation in the University of Tokyo Hospital between January 2011 and December 2016 were analyzed retrospectively. We defined a two-level or more difference between clinical and pathological T stages as over-diagnosis or under-diagnosis.

Results

Nine patients were over-diagnosed in T stage preoperatively. The rate of over-diagnosis was 0.9%. At least three main factors for over-diagnosis were identified: close-to-circumferential or obstructive lesion; a rough appearance in the adipose tissues around the tumor on CT; and a tumor with a depressed structure.

Conclusions

Clinical T stage is overestimated with a marked difference from pathological T stage in approximately 1% of CRC patients. Further progress in diagnostic modalities is required for more accurate staging.

•

The rate of one-level over-diagnosis in T stage was 14.8%.

•

The rate of two-levels or more over-diagnosis in T stage was 0.9%.

•

At least three main factors for two-levels or more over-diagnosis were identified.

ACR Appropriateness Criteria® Pretreatment Staging of Colorectal Cancer

Colorectal cancers are common tumors in the United States and appropriate imaging is essential to direct appropriate care. Staging and treatment differs between tumors arising in the colon versus the rectum. Local staging for colon cancer is less integral to directing therapy given radical resection is often standard. Surgical options for rectal carcinoma are more varied and rely on accurate assessment of the sphincter, circumferential resection margins, and peritoneal reflection. These important anatomic landmarks are best appreciated on high-resolution imaging with transrectal ultrasound or MRI. When metastatic disease is suspected, imaging modalities that provide a global view of the body, such as CT with contrast or PET/CT may be indicated. Rectal cancer often metastasizes to the liver and so MRI of the liver with and without contrast provides accurate staging for liver metastases. This article focuses on local and distant staging and reviews the appropriateness of different imaging for both variants. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Clinical Value of CT Colonography Versus Preoperative Colonoscopy in the Surgical Management of Occlusive Colorectal Cancer

OBJECTIVE

CT colonography (CTC) has been recognized as a complementary approach to evaluating the entire colon after incomplete colonoscopy (IC) in patients with occlusive colorectal cancer (CRC). The objective of this study is to evaluate changes in preoperative surgical planning after CTC is performed for patients with occlusive CRC and IC in an oncologic hospital.

MATERIALS AND METHODS

This retrospective study included 65 consecutive patients with occlusive CRC who underwent CTC after IC at our institution from February 2000 to April 2016. CTC examinations and radiology reports were reviewed by an abdominal radiologist. Clinical information was obtained from a review of the electronic medical record.

RESULTS

CTC contributed to a change in the initial surgical plan of the surgeon for 14 of 65 patients (21.5%). In these 14 patients, CTC detected five synchronous proximal colon polyps (35.7%), five synchronous proximal cancers (35.7%), two imprecise CRC locations (14.3%), one case of proximal colon ischemia (7.1%), and one instance of tumor infiltration of the urinary bladder (7.1%). All CTC findings were confirmed at surgery, and all proximal colon polyps were subsequently confirmed to be advanced adenomas.

CONCLUSION

The preoperative CTC findings optimized the surgical management plan for 21.5% of patients with occlusive CRC and IC.

High-risk features in potentially resectable colon cancer: a prospective MDCT-pathology agreement study

PURPOSE

Neoadjuvant chemotherapy in potentially resectable high-risk Stage II and Stage III colon cancer has demonstrated promising results in the PRODIGE 22-ECKINOXE Phase II trial. Identification of adverse morphologic features, namely T3 with >5 mm extramural extension/T4 stages and/or N2, is fundamental and requires accurate noninvasive imaging. Our aim was to assess the value of optimized preoperative MDCT to stratify potentially resectable colon cancer patients for neoadjuvant therapy.

METHODS

this is an observational prospective cross-sectional radiologic-pathologic agreement study. All patients with colon cancer referred to our Institution's Radiology department for preoperative MDCT staging between 01-10-2013 and 11-02-2015 underwent independent reading based on axial and multiplanar reconstruction images by 3 radiologists with 3, 6, and 20 years of experience in gastrointestinal radiology. T stage, extramural extension if T3 (≤5 mm or >5 mm), and N stage were recorded. Surgical specimens subsequently obtained underwent micro-pathologic analysis by a gastrointestinal pathologist with 9 years of experience in gastrointestinal pathology. Main outcome measures were sensitivity, specificity, PPV, NPV, AUROC, diagnostic accuracy, and interobserver agreement of optimized MDCT, and pathologic analysis of the surgical specimen considered the reference standard.

RESULTS

74 patients [43 males; median age 73 (45-89)] were eligible. MDCT sensitivity, specificity, PPV, NPV, AUROC, and diagnostic accuracy ranged between 42.9-76.2, 75.5-90.6, 55.2-76.2, 80.0-90.6, 0.67-0.83 and 0.76-0.86%, respectively, for the identification of T3 > 5 mm/T4 disease, with moderate interobserver agreement (0.49); and 8.3-33.3, 93.5-98.4, 20-66.7, 84.1-88.2, 0.51-0.65 and 0.80-0.86%, respectively, for the identification of N2 disease, with absent interobserver agreement (0.10).

CONCLUSIONS

Specificity of MDCT in the stratification of patients for neoadjuvant therapy may be high enough to prevent overtreatment. However, it may lead to undertreatment in a meaningful proportion of patients. Observer performance may benefit from targeted training programs, given the variability and observer dependence of the results. Limitations include 4-slice MDCT equipment, time to surgery and lack of long-term outcome information based on imaging parameters per se.

Diagnostic Accuracy of CT for Local Staging of Colon Cancer: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this article is to determine the accuracy of CT in the detection of tumor invasion beyond the bowel wall and nodal involvement of colon carcinomas. A literature search was performed to identify studies describing the accuracy of CT in the staging of colon carcinomas. Studies including rectal carcinomas that were inseparable from colon carcinomas were excluded. Publication bias was explored by using a Deeks funnel plot asymmetry test. A hierarchic summary ROC model was used to construct a summary ROC curve and to calculate summary estimates of sensitivity, specificity, and diagnostic odds ratios (ORs).

CONCLUSION

On the basis of a total of 13 studies, pooled sensitivity, specificity, and diagnostic ORs for detection of tumor invasion beyond the bowel wall (T3-T4) were 90% (95% CI, 83-95%), 69% (95% CI, 62-75%), and 20.6 (95% CI, 10.2-41.5), respectively. For detection of tumor invasion depth of 5 mm or greater (T3cd-T4), estimates from four studies were 77% (95% CI, 66-85%), 70% (95% CI, 53-83%), and 7.8 (95% CI, 4.2-14.2), respectively. For nodal involvement (N+), 16 studies were included with values of 71% (95% CI, 59-81%), 67% (95% CI, 46-83%), and 4.8 (95% CI, 2.5-9.4), respectively. Two studies using CT colonography were included with sensitivity and specificity of 97% (95% CI, 90-99%) and 81% (95% CI, 65-91%), respectively, for detecting T3-T4 tumors. CT has good sensitivity for the detection of T3-T4 tumors, and evidence suggests that CT colonography increases its accuracy. Discriminating between T1-T3ab and T3cd-T4 cancer is challenging, but data were limited. CT has a low accuracy in detecting nodal involvement.

Reducing the Radiation Dose for CT Colonography: Effect of Low Tube Voltage and Iterative Reconstruction

RATIONALE AND OBJECTIVES

The purpose of this study was to assess the effect of a low-tube-voltage technique and iterative reconstruction (IR) on the radiation dose and image quality of computed tomography colonography (CTC).

MATERIALS AND METHODS

We studied 30 patients (14 women and 16 men; mean age, 64.5 ± 13.1 years; range, 39-90 years) with colorectal cancer referred for surgical treatment. All underwent CTC with fecal tagging under a standard 120-kVp protocol in the supine position and a 100-kVp protocol in the prone position. The 120-kVp images were reconstructed with filtered back projection (FBP). The 100-kVp images were postprocessed using FBP and a hybrid type of IR (adaptive iterative dose reduction 3D). The effective radiation dose (ED), image noise, and contrast-to-noise ratio (CNR) were compared among the three protocols. The visual image quality was scored on a four-point scale.

RESULTS

The mean ED was significantly lower under the 100-kVp protocol than the 120-kVp protocol, resulting in a 27% radiation dose decrease (3.5 ± 2.0 vs 2.5 ± 1.5 mSv; P < .01). Image noise decreased by 48%, and the mean attenuation of tagged fluid increased from 452 to 558 HU on images acquired at 100 kVp with IR compared to that in the 120-kVp protocol; these differences were significant. The mean CNR was significantly higher under the 100 kVp with IR than the other two protocols. We found no significant differences in the visual scores for diagnostic utility between the 100 kVp with IR and the 120 kVp with FBP protocol (P = .10).

CONCLUSIONS

Low-tube-voltage CTC reduced the radiation dose by approximately 27% while maintaining the image quality.

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.

Routine use of positron-emission tomography/computed tomography for staging of primary colorectal cancer: does it affect clinical management?

Background

The use of positron emission tomography-computed tomography (PET/CT) for the preoperative staging of patients with colon and rectal cancer has increased steadily over the last decade. The aim of this study was to evaluate the effect of PET/CT on the preoperative staging and clinical management of patients with colorectal cancer.

Methods

Between December 2010 and February 2012, 64 consecutive patients with colorectal cancer were evaluated with both PET/CT scans and conventional preoperative imaging studies. We prospectively recorded the medical reports of these patients. The PET/CT findings were compared with conventional imaging studies and the rate of over-staging or down-staging and changes in clinical management were evaluated. The correlation of the PET/CT with the conventional imaging was compared by a kappa agreement coefficient. Differences in the accuracy for N and T staging were assessed by χ2 and related-samples marginal homogeneity tests.

Results

Thirty-nine (60.9%) patients had rectal cancer and 25 (39.1%) had colon cancer. Based on PET/CT, additional lesions were found in 6 (9.4%) of the patients: hilar and paratracheal lesions in 4 patients, hepatic in 1 and supraclavicular in 1 patient. In four of six patients, detailed imaging studies or biopsies revealed chronic inflammatory changes. Hepatic and supraclavicular involvement was confirmed in two patients. Therefore, the false positivity rate of PET/CT was 6.25%. Based on the additional PET/CT, 2 (3.2%) patients had a change in surgical management. A chemotherapy regimen was administered to the patient with a 1.5 cm hepatic metastasis near the right hepatic vein; for another patient with an identified supraclavicular lymph node metastasis, a simultaneous excision was performed.

Conclusions

Routine use of PET/CT for preoperative staging did not impact disease management for 96.8% of our patients. The results of our study conclude that PET/CT should not be routinely used for primary staging of colorectal cancer. More studies are required for identifying the subgroup of patients who might benefit from a PET/CT in their initial staging.