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

CT Colonography Reporting and Data System (C-RADS): Version 2023 Update

The CT Colonography Reporting and Data System (C-RADS) has withstood the test of time and proven to be a robust classification scheme for CT colonography (CTC) findings. C-RADS version 2023 represents an update on the scheme used for colorectal and extracolonic findings at CTC. The update provides useful insights gained since the implementation of the original system in 2005. Increased experience has demonstrated confusion on how to classify the mass-like appearance of the colon consisting of soft tissue attenuation that occurs in segments with acute or chronic diverticulitis. Therefore, the update introduces a new subcategory, C2b, specifically for mass-like diverticular strictures, which are likely benign. Additionally, the update simplifies extracolonic classification by combining E1 and E2 categories into an updated extracolonic category of E1/E2 since, irrespective of whether a finding is considered a normal variant (category E1) or an otherwise clinically unimportant finding (category E2), no additional follow-up is required. This simplifies and streamlines the classification into one category, which results in the same management recommendation.

Changing the routine: a move to patient initiated follow up to improve surgical outpatient clinic

Introduction

Patient initiated follow up (PIFU) allows patients to initiate a hospital follow up appointment on an ‘as required’ basis in contrast to the traditional physician‐initiated model. We present a clinical pathway for patients referred with rectal bleeding at a large tertiary public hospital in South Auckland, New Zealand and demonstrate the utility of PIFU and its impact on reducing follow up appointments.

Method

The purpose of the pathway was to allow standardized care by the clinicians and allow for PIFU. Two separate protocols were developed ‐ ‘Painful PR bleeding’ and ‘Painless PR bleeding’. A new clinic (NC) was started following these protocols, and this was compared to historical controls (HC). The primary outcome was the rate of follow up appointments.

Results

There were 133 patients in the NC and 135 in the HC, with significantly less follow ups in the NC (6% versus 45%, p < 0.0001). A small percentage of patients in the NC group were directly discharged (10%) whilst 70% of patients were discharged with a PIFU card. Thirty phone calls were made using PIFU, with 10 patients returning to clinic and 20 requiring advice and reassurance only. At 5 year follow up, there was a single colorectal malignancy found in both groups.

Conclusion

Initiating a protocol that includes patient initiated follow up vastly reduces the need for routine return to clinic for the majority of patients, without sacrificing patient care. A protocolised approach to clinic for other areas in general surgery should be considered.

EXTRACOLONIC FINDINGS-IDENTIFICATION AT LOW-DOSE CTC

In contrast to optical colonoscopy, computed tomography colonography (CTC) has the ability to reveal pathology outside of the colon. While identification of colorectal lesions at CTC requires only limited radiation dose, the detection of abnormalities in extracolonic soft tissue requires more radiation. The purpose of this study was to investigate the influence of ultra-low-dose (ULD) CTC on the detection and characterisation of extracolonic findings. In a prospective study 49 patients with colorectal symptoms were examined with CTC adding a ULD series (mean effective dose 0.9 ± 0.4 mSv) to the normal unenhanced standard dose (SD) series (mean effective dose 3.6 ± 1.2 mSv). Five radiologists individually and blindly evaluated the ULD, followed by evaluation of the SD after ≥9 weeks (median 35 weeks). A ViewDEX-based examination protocol was used, including a confidence scale and a graded assessment of need for follow-up according to the CTC Reporting and Data System (C-RADS E0-E4). The reference findings comprised the combined information from CTC (ULD, SD and contrast-enhanced CTC series) and a 4-year radiological and clinical follow-up. For the overall detection of reference findings (E2-E4) we found a statistically significant difference in favour of SD. This, however, was not the case when looking at classification of possibly important/important reference findings (E3-E4). Our results suggest that CTC with ULD (0.9 mSv) is comparable to SD (3.6 mSv) for identification of clinically relevant extracolonic pathology, but there is a large inter-observer variability.

The yield and patient factors associated with CT colonography C-RADS results in a non-screening patient population

OBJECTIVES

To determine the proportion of diagnostic computed tomography colonography (CTC) Reporting and Data System (C-RADS) categories in a non-screening population, and which patient factors are associated with a positive CTC (C2-4), a non-diagnostic CTC (C0), and potentially relevant extracolonic findings (ECF, E3-4).

METHODS

Diagnostic CTCs performed at a single academic center from 2017 to 2018 were retrospectively reviewed. For each examination, the indications, age, sex, admission status, and C-RADS categories were recorded. Multivariate logistic regression was performed of patient demographic factors and clinical indications, with adjusted odds ratios (OR) and 95% confidence intervals.

RESULTS

1373 CTCs were included. The mean age was 66.4 ± 13 years (range 24-97). There were 782 women and 75 inpatients. The number of CTCs reported as C0-C4 were 194/1373 (14.1%), 970/1373 (70.6%), 77/1373 (5.6%), 86/1373 (6.3%), and 46/1373 (3.4%), respectively, and 134/1373 (9.8%), 960/1373 (69.9%), 173/1373 (12.6%), and 106/1373 (7.7%) CTCs were reported as E1-4, respectively. Factors that demonstrated the strongest associations were as follows: with C2-4, age groups 50-79 (OR 2.8, 95% confidence interval 1.4-6.1), 80-89 (6.2, 2.9-14.5) and ≥ 90 (7.6, 2.0-29.1), and inpatients (3.4, 1.8-6.4); with C0, age groups 50-79 (5.9, 2.2-24.4), 80-89 (9.8, 3.4-41.8), and ≥ 90 (22.5, 5.8-113.0), incomplete colonoscopy (3.2, 2.0-5.1) and melena or gastrointestinal bleeding (4.1, 1.8-9.4); and with E3-4, age groups 50-79 (1.6, 1.0-2.9), 80-89 (2.0, 1.1-3.9), and ≥ 90 (3.2, 1.2-8.8), and inpatients (2.3, 1.3-3.9).

CONCLUSION

Older age is increasingly associated with a positive test, a non-diagnostic test and potentially relevant ECF. Inpatients are also associated with positive tests and E3-4 findings. Symptoms are not strongly associated with a positive CTC.

Computed tomography colonography: a retrospective analysis of outcomes of 2 years experience in a district general hospital

BACKGROUND

Colonoscopy is the gold-standard investigation for direct luminal visualization of the large bowel. Studies have shown the efficacy of computed tomography colonography (CTC) is equivalent to colonoscopy in both cancer and polyp detection.

METHODS

A retrospective review of patients undergoing CTC from January 2013 to October 2014 was performed. Patient demographics, indication for investigation, computed tomography findings, optical colonoscopy findings and histology results were recorded.

RESULTS

Seven hundred and fifty-eight CTC were performed. Three hundred and seventeen patients were male (42%) and 441 (58%) were female. Endoscopy was advised in 209 cases. One hundred and twenty (16%) were deemed suspicious for cancer of whom 96 (80%) had optical colonoscopy. A total of 12 colorectal cancers were detected. Potential polyps were noted in 58 cases (8%). Forty-four patients underwent endoscopy (75%) and 17 polyps confirmed (38%). Two patients had foci of invasive cancer histologically. Significant extracolonic findings were identified in 60%, including five cases of gastric carcinomas. The most common other findings were gallstones and hernias.

CONCLUSION

The rate of colorectal cancer detection in this study was 2%. The rate of biopsy proven cancer was 10% following a suspicious colonogram. Endoscopic correlation was not obtained in 20% of cases of radiological suspicion. CTC is as efficacious as optical colonoscopy for colorectal cancer and polyp detection.

Comparison of extracolonic findings and clinical outcomes in a screening and diagnostic CT colonography population

PURPOSE

To compare the distribution of extracolonic findings and clinical outcomes between screening and diagnostic CT colonography (CTC) populations.

METHODS

388 consecutive patients (369 men, 19 women; mean ± SD age 67.8 ± 10 years) who underwent first-time CTC (4/2011-4/2017) at a Veteran's Affairs Medical Center were divided into screening (asymptomatic) or diagnostic (symptomatic) cohorts based on CTC indication. CTC reporting and data system E-scores for extracolonic findings were retrospectively assigned based on prospective CTC radiologic reports. Multinomial logistic regression was used to examine the association between E-scores and CTC indication. Electronic medical records of all patients with E3 or E4 scores were reviewed (median follow-up 2.8 years) to determine clinical outcomes.

RESULTS

68% (262/388) underwent screening and 32% (126/388) diagnostic CTC. 7.2% (28/388) had extracolonic findings considered potentially significant (E4), 4.4% (17/388) had indeterminate but likely unimportant findings (E3), and 88.4% (347/388) had normal or unimportant findings (E1 or E2). E-scores were not significantly different between screening and diagnostic CTC when adjusted for age, gender, and prior imaging (p = 0.44). 4.6% (12/262) of patients with E3/E4 findings in the screening cohort demonstrated clinically significant outcomes, compared with 4.0% (5/126) in the diagnostic cohort, including a total of three extracolonic malignancies (0.8%) and three abdominal aortic aneurysms (0.8%). 4.6% (18/388) underwent follow-up imaging studies to confirm a benign outcome after detection of a category E3/E4 finding.

CONCLUSIONS

The distribution of extracolonic findings and clinical outcomes were not statistically significantly different between screening and diagnostic CTC populations.

Detection of potentially relevant extracolonic and colorectal findings at CT colonography in a low-risk symptomatic patient population

PURPOSE

CT colonography (CTC) is a widely accepted examination tool for detection of colorectal lesions but evidence of the proportions of relevant extracolonic findings (ECF) in a large symptomatic but still relatively low-risk cohort is lacking, as well as their relationship to symptoms, age, and sex.

METHODS

All patients (n = 3208) with colorectal symptoms, imaged between January 2007 and September 2016 with first-time CTC, were retrospectively selected. The majority (96.7%) was examined with low-dose unenhanced protocol. The most relevant ECF and colorectal lesions (≥6 mm) were prospectively assessed according to C-RADS classifications. Follow-up was elaborated based on the electronic record review. Chi-square test was utilized for evaluating the associations between relevant findings and symptoms, age, and sex.

RESULTS

A total of 270 (8.4%) patients were classified as C-RADS E3, 63 (2.0%) patients as C-RADS E4, and 437 (13.6%) patients were assessed with colorectal lesions (C-RADS C2-4). At follow-up, two thirds of ECF turned out to be a malignancy or relevant disease that required further medical attention. The proportion of ECF was not related to specific colorectal symptoms. Patients aged ≥65 years and men had significantly higher proportions of ECF than younger patients (C-RADS E3 p = 0.005; C-RADS E4 p < 0.001) and women (C-RADS E3 p = 0.013; C-RADS E4 p = 0.009), respectively.

CONCLUSION

Proportions of relevant ECF and colorectal findings are relatively low in symptomatic low-risk patients. By use of CTC as a singular examination, especially in elderly patients, most colonoscopies can be avoided with the benefit of diagnosing relevant ECF without introducing substantial over-diagnosis.

Renal incidental findings on computed tomography: Frequency and distribution in a large non selected cohort

Renal incidental findings (IFs) are common. However, previous reports investigated renal IFs were limited to patient selection. The purpose of this study was to estimate the prevalence and distribution of all renal IFs on computed tomography (CT) in a large patient collective.All patients, who underwent CT investigations of the abdominal region at our institution in the time period between January 2006 and February 2014 were included in this study. Inclusion criteria were as follows: no previous history of renal diseases and well image quality. Patients with known kidney disorders were excluded from the study. Overall, 7365 patients meet the inclusion criteria were identified. There were 2924 (39.7%) women and 4441 men (60.3%) with a mean age of 59.8 ± 16.7 years. All CTs were retrospectively analyzed in consensus by 2 radiologists. Collected data were evaluated by means of descriptive statistics.Overall, 2756 patients (37.42% of all included patients) showed 3425 different renal IFs (1.24 findings per patient). Of all renal IFs, 123 (3.6%) findings were clinically relevant, 259 (7.6%) were categorized as possibly clinically relevant, and 3043 (88.8%) were clinically non relevant.Different renal IFs can be detected on CT. The present study provides a real prevalence and proportion of them in daily clinical routine. Kidneys should be thoroughly evaluated because of the fact that incidental renal findings occur frequently.

Sub-milliSievert ultralow-dose CT colonography with iterative model reconstruction technique

Purpose. The purpose of this study was to evaluate the technical and diagnostic performance of sub-milliSievert ultralow-dose (ULD) CT colonograpy (CTC) in the detection of colonic and extracolonic lesions.

Materials and Methods. CTC with standard dose (SD) and ULD acquisitions of 64 matched patients, half of them with colonic findings, were reconstructed with filtered back projection (FBP), hybrid (HIR) and iterative model reconstruction techniques (IMR). Image noise in six colonic segments, in the left psoas muscle and aorta were measured. Image quality of the left adrenal gland and of the colon in the endoscopic and 2D view was rated on a five point Likert scale by two observers, who also completed the reading of CTC for colonic and extracolonic findings.

Results. The mean radiation dose estimate was 4.1 ± 1.4 mSv for SD and 0.86 ± 0.17 mSv for ULD for both positions (p < 0.0001). In ULD-IMR, SD-IMR and SD-HIR, the endoluminal noise was decreased in all colonic segments compared to SD-FBP (p < 0.001). There were 27 small (6–9 mm) and 17 large (≥10 mm) colonic lesions that were classified as sessile polyps (n = 38), flat lesions (n = 3), or as a mass (n = 3). Per patient sensitivity and specificity were 0.82 and 0.93 for ULD-FBP, 0.97 and 0.97 for ULD-HIR, 0.97 and 1.0 for ULD-IMR. Per polyp sensitivity was 0.84 for ULD-FBP, 0.98 for ULD-HIR, 0.98 for ULD-IMR. Significantly less extracolonic findings were detected in ULD-FBP and ULD-HIR, but in the E4 category by C-RADS (potentially important findings), the detection was similar.

Conclusion. Both HIR and IMR are suitable for sub-milliSievert ULD CTC without sacrificing diagnostic performance of the study.

Potentially Important Extracolonic Findings at Screening CT Colonography: Incidence and Outcomes Data From a Clinical Screening Program

OBJECTIVE

The effect of detection of extracolonic findings at screening CT colonography (CTC) remains controversial. Our objective is to analyze the incidence and outcomes of unsuspected potentially significant (CT Colonography Reporting and Data System [C-RADS] extracolonic category E4) findings in a population undergoing clinical CTC screening.

SUBJECTS AND METHODS

Over the course of 99 months (April 1, 2004, through June 30, 2012), 7952 consecutive asymptomatic adults (3675 men and 4277 women; mean [± SD] age, 56.7 ± 7.3 years) underwent first-time screening CTC. Examinations were prospectively interpreted by radiologists within our abdominal imaging section, and extracolonic findings were recorded and categorized. Potentially significant (i.e., C-RADS extracolonic category E4) findings were retrospectively reviewed with additional analysis of follow-up (range, 2-10 years) and ultimate clinical outcome.

RESULTS

Overall, 2.5% (202/7952) of patients had a potentially significant (C-RADS category E4) extracolonic finding for which further imaging (56%; 113/202) or clinical follow-up (44%; 89/202) was recommended. No patients had multiple category E4 findings. Twenty-two patients were lost to follow-up. Of the remaining 180 patients, 68% (123/180) proved to have clinically significant disease, including 23% (42/180) with malignant or potentially malignant neoplasms and 32% (57/180) with abdominal aortic or other visceral artery aneurysms requiring treatment or surveillance. The most commonly involved organs and systems included the vascular system (26%; 53/202), the genitourinary system (18%; 36/202), the liver (15%; 30/202), the gastrointestinal system (9.9%; 20/202), the lungs (9.4%; 19/202), and the gynecologic system (6.9%; 14/202).

CONCLUSION

Potentially significant extracolonic findings in asymptomatic adults at screening CTC are uncommon (2-3% of cases). However, most of these findings (68%) will prove to be clinically significant, including a number of malignancies and aneurysms requiring treatment or surveillance.

Submilisievert ultralow-dose CT colonography using iterative reconstruction technique: a feasibility study

BACKGROUND

Computed tomography (CT) colonography is a well established modality for the examination of symptomatic patients as well as in screening. Recent technical advances in improving image quality by iterative reconstruction contribute to the reduction of the radiation dose which is a major concern in CT imaging.

PURPOSE

To evaluate image quality of ultralow-dose submilisievert CT colonography using hybrid iterative reconstruction technique.

MATERIAL AND METHODS

Sixteen patients underwent contrast-enhanced CT colonography with standard protocol in supine position and ultralow-dose protocol in prone position. Ultralow-dose datasets were reconstructed with filtered back projection and an advanced hybrid iterative reconstruction technique. Two radiologists independently evaluated 96 colonic segments for image quality in the endoluminal view and axial thin sections. Colonic distension, smoothness of colonic wall and distortion of folds in the endoluminal view, sharpness of colonic wall delineation, perceived image noise, and presence of photon starvation artifact were rated on a five-point scale. Intraluminal noise expressed as standard deviation of Hounsfield density was measured in all segments.

RESULTS

The mean radiation dose was 0.42 mSv and 5.48 mSv in prone and supine scans, respectively. All distended segments were rated evaluable in standard dose and ultralow-dose series reconstructed with the iterative reconstruction technique, whereas in 61% segments image quality was rated poor or unacceptable in ultralow-dose series where filtered back projection was used with worst ratings in the rectum and the sigmoid colon.

CONCLUSION

This pilot study shows that iterative reconstruction technique is a feasible method to decrease the radiation dose from CT colonography for both positions below 1mSv. Further investigations of larger scale need to be done to clarify, whether such a low radiation dose would influence the detection of polyps.