UNASSIGNED: Diagnostic reference levels (DRLs) are an important metric in identifying abnormally high radiation doses in diagnostic examinations. National DRLs for CT colonography do not currently exist in South Africa, but there are efforts to collect data for a national DRL project.
UNASSIGNED: This study investigated radiation doses for CT colonography in adult patients at a large tertiary hospital in South Africa with the aim of setting local DRLs.
UNASSIGNED: Patient data from two CT scanners (Philips Ingenuity and Siemens Somatom go.Top) in the period March 2020 - March 2023 were obtained from the hospital\'s picture archiving and communication system (PACS) (n = 115). Analysis involved determining the median computed tomography dose index-volume (CTDIvol) and dose-length product (DLP) values. The findings were compared with DRLs established internationally.
UNASSIGNED: Ingenuity median CTDIvol was 20 mGy and DLP was 2169 mGy*cm; Somatom median CTDIvol was 6 mGy and DLP was 557 mGy*cm. Ingenuity exceeded the United Kingdom\'s (UK) recommended DRLs by 82% and 214%, respectively. Somatom median CTDIvol and DLP were 45% and 19% lower than UK NDRLs.
UNASSIGNED: Somatom\'s tin filter and other dose reduction features provided significant dose reduction. These data were used to set DRLs for CT colonography at the hospital; CTDIvol: 6 mGy and DLP: 557 mGy*cm.
UNASSIGNED: In addition to informing radiation protection practices at the level of the institution, the established local DRLs contribute towards implementing regional and national DRLs.

OBJECTIVE: To evaluate the image quality of low-dose CT colonography (CTC) using deep learning-based reconstruction (DLR) compared to iterative reconstruction (IR).
METHODS: Adults included in the study were divided into four groups according to body mass index (BMI). Routine-dose (RD: 120 kVp) CTC images were reconstructed with IR (RD-IR); low-dose (LD: 100kVp) images were reconstructed with IR (LD-IR) and DLR (LD-DLR). The subjective image quality was rated on a 5-point scale by two radiologists independently. The parameters for objective image quality included noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The Friedman test was used to compare the image quality among RD-IR, LD-IR and LD-DLR. The KruskalWallis test was used to compare the results among different BMI groups.
RESULTS: A total of 270 volunteers (mean age: 47.94 years ± 11.57; 115 men) were included. The effective dose of low-dose CTC was decreased by approximately 83.18% (5.18mSv ± 0.86 vs. 0.86mSv ± 0.05, P < 0.001). The subjective image quality score of LD-DLR was superior to that of LD-IR (3.61 ± 0.56 vs. 2.70 ± 0.51, P < 0.001) and on par with the RD- IR\'s (3.61 ± 0.56 vs. 3.74 ± 0.52, P = 0.486). LD-DLR exhibited the lowest noise, and the maximum SNR and CNR compared to RD-IR and LD-IR (all P < 0.001). No statistical difference was found in the noise of LD-DLR images between different BMI groups (all P > 0.05).
CONCLUSIONS: Compared to IR, DLR provided low-dose CTC with superior image quality at an average radiation dose of 0.86mSv, which may be promising in future colorectal cancer screening.

BACKGROUND. Approximately one-third of the eligible U.S. population have not undergone guideline-compliant colorectal cancer (CRC) screening. Guidelines recognize various screening strategies to increase adherence. CMS provides coverage for all recommended screening tests except CT colonography (CTC). OBJECTIVE. The purpose of this study was to compare CTC and other CRC screening tests in terms of associations of utilization with income, race and ethnicity, and urbanicity in Medicare fee-for-service beneficiaries. METHODS. This retrospective study used CMS Research Identifiable Files from January 1, 2011, through December 31, 2020. These files contain claims information for 5% of Medicare fee-for-service beneficiaries. Data were extracted for individuals 45-85 years old, and individuals with high CRC risk were excluded. Multivariable logistic regression models were constructed to determine the likelihood of undergoing CRC screening tests (as well as of undergoing diagnostic CTC, a CMS-covered test with similar physical access as screening CTC) as a function of income, race and ethnicity, and urbanicity while controlling for sex, age, Charlson comorbidity index, U.S. census region, screening year, and related conditions and procedures. RESULTS. For 12,273,363 beneficiary years (mean age, 70.5 ± 8.2 [SD] years; 2,436,849 unique beneficiaries: 6,774,837 female beneficiaries, 5,498,526 male beneficiaries), there were 785,103 CRC screenings events, including 645 for screening CTC. Compared with individuals living in communities with per capita income of less than US$25,000, individuals in communities with income of US$100,000 or more had OR for undergoing screening CTC of 5.73, optical colonoscopy (OC) of 1.36, sigmoidoscopy of 1.03, guaiac fecal occult blood test or fecal immunochemical test of 1.50, stool DNA of 1.43, and diagnostic CTC of 2.00. The OR for undergoing screening CTC was 1.00 for Hispanic individuals and 1.08 for non-Hispanic Black individuals compared with non-Hispanic White individuals. Compared with the OR for undergoing screening CTC for residents of metropolitan areas, the OR was 0.51 for residents of micropolitan areas and 0.65 for residents of small or rural areas. CONCLUSION. The association with income was substantially larger for screening CTC than for other CRC screening tests or for diagnostic CTC. CLINICAL IMPACT. Medicare\'s noncoverage for screening CTC may contribute to lower adherence with CRC screening guidelines for lower-income beneficiaries. Medicare coverage of CTC could reduce income-based disparities for individuals avoiding OC owing to invasiveness, need for anesthesia, or complication risk.

Colon cancer is the third most common malignancy in Canada. Computed tomography colonography (CTC) provides a creditable and validated option for colon screening and assessment of known pathology in patients for whom conventional colonoscopy is contraindicated or where patients self-select to use imaging as their primary modality for initial colonic assessment. This updated guideline aims to provide a toolkit for both experienced imagers (and technologists) and for those considering launching this examination in their practice. There is guidance for reporting, optimal exam preparation, tips for problem solving to attain high quality examinations in challenging scenarios as well as suggestions for ongoing maintenance of competence. We also provide insight into the role of artificial intelligence and the utility of CTC in tumour staging of colorectal cancer. The appendices provide more detailed guidance into bowel preparation and reporting templates as well as useful information on polyp stratification and management strategies. Reading this guideline should equip the reader with the knowledge base to perform colonography but also provide an unbiased overview of its role in colon screening compared with other screening options.

OBJECTIVE: To investigate the differentiation of premalignant from benign colorectal polyps detected by CT colonography using deep learning.
METHODS: In this retrospective analysis of an average risk colorectal cancer screening sample, polyps of all size categories and morphologies were manually segmented on supine and prone CT colonography images and classified as premalignant (adenoma) or benign (hyperplastic polyp or regular mucosa) according to histopathology. Two deep learning models SEG and noSEG were trained on 3D CT colonography image subvolumes to predict polyp class, and model SEG was additionally trained with polyp segmentation masks. Diagnostic performance was validated in an independent external multicentre test sample. Predictions were analysed with the visualisation technique Grad-CAM++.
RESULTS: The training set consisted of 107 colorectal polyps in 63 patients (mean age: 63 ± 8 years, 40 men) comprising 169 polyp segmentations. The external test set included 77 polyps in 59 patients comprising 118 polyp segmentations. Model SEG achieved a ROC-AUC of 0.83 and 80% sensitivity at 69% specificity for differentiating premalignant from benign polyps. Model noSEG yielded a ROC-AUC of 0.75, 80% sensitivity at 44% specificity, and an average Grad-CAM++ heatmap score of ≥ 0.25 in 90% of polyp tissue.
CONCLUSIONS: In this proof-of-concept study, deep learning enabled the differentiation of premalignant from benign colorectal polyps detected with CT colonography and the visualisation of image regions important for predictions. The approach did not require polyp segmentation and thus has the potential to facilitate the identification of high-risk polyps as an automated second reader.
CONCLUSIONS: • Non-invasive deep learning image analysis may differentiate premalignant from benign colorectal polyps found in CT colonography scans. • Deep learning autonomously learned to focus on polyp tissue for predictions without the need for prior polyp segmentation by experts. • Deep learning potentially improves the diagnostic accuracy of CT colonography in colorectal cancer screening by allowing for a more precise selection of patients who would benefit from endoscopic polypectomy, especially for patients with polyps of 6-9 mm size.

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

Fecal impaction is the impaired excretion of a large fecal mass, and mild cases are treated by enema and osmotic laxatives. However, treatment-resistant cases need more invasive alternatives. A woman in her 60s presented with abdominal discomfort. Her abdomen was soft and without tenderness. Computed tomography revealed a large mass of feces in her sigmoid colon and no intestinal dilatation proximal to the mass. Endoscopy confirmed a fecal mass occupying the lumen. A glycerin enema, oral administration of polyethylene glycol, and enteral administration of amidotrizoic acid during colonoscopy were ineffective. We maneuvered a guidewire to form a loop at the tip of an endoscope, with which we subdivided the mass for successful removal. The patient\'s abdominal discomfort disappeared immediately. Endoscopic disimpaction is far less invasive than surgery and should be considered when treating fecal impaction cases, without severe obstructive colitis, which are nonresponsive to conservative treatment.

BACKGROUND: The digestive involvement of endometriosis accounts for up to 20-25% of deep localisations. Precise mapping of digestive lesions is essential in order to plan surgery and specialized teams. The aim of this study is to assess the contribution of the MRI-coloscan couple in the preoperative assessment of digestive endometriosis.
METHODS: We analyzed 45 files of patients referred for suspected digestive endometriosis. They had all undergone a preoperative MRI and coloscan associated with surgery throughout the year. We first compared the data collected in imaging, and then compared the synthesis of this data with the surgical procedure performed.
RESULTS: 35 patients required digestive surgery. 24 of 45 files were concordant in MRI and coloscanner. Data from MRI alone matched with surgery in 69% of cases, against 84% for the coloscan. The synthesis allowed a concordance of 89%. 25 segmental resections, 2 discoid and 16 shaving were performed. The use of coloscan made up for nine extra cases: the detection of four additional cases of multifocality, a single undiagnosed case of a deep lesion, and allowed to specify the depth of the involvement in four cases. On the contrary, the MRI was correct compared to the CT in four cases. The presence of a digestive surgeon was necessary in 53% of cases.
CONCLUSIONS: In the era of imaging staging, it would seem interesting to turn towards a subclassification of the digestive involvement of endometriosis in order to decide which surgery to perform. In our experience, the coloscan is a useful complement of MR, especially to assess the depth of involvement and the multifocality.

OBJECTIVE: The aim of this study is to reveal the vascular branching variation in SFC (splenic flexure cancer) patients using the preoperative three-dimensional computed tomography angiography with colonography (3D-CTAC).
METHODS: We retrospectively analyzed patients with SFC who underwent preoperative 3D-CTAC between January 2014 and December 2019.
RESULTS: Among 1256 colorectal cancer (CRC) patients, 96 (7.6%) manifested SFC. The arterial branching from the superior mesenteric artery (SMA) was classified into five patterns, as follows: (type 1A) the left branch of middle colic artery (LMCA) diverged from middle colic artery (MCA) (N = 47, 49.0%); (2A) the LMCA diverged from the MCA and the accessory middle colic artery (AMCA) (N = 26, 27.1%); (3A) the LMCA independently diverged from the SMA (N = 16, 16.7%); (4A) the LMCA independently diverged from the SMA and AMCA (N = 3, 3.1%); (5A) only the AMCA and the LMCA was absent (N = 4, 4.1%). Venous drainage was classified into four patterns, as follows: (type 1V) the SFV flows into the inferior mesenteric vein (IMV) then back to the splenic vein (N = 50, 52.1%); (2V) the SFV flows into the IMV then back to the superior mesenteric vein (SMV) (N = 19, 19.8%); (type 3V) the SFV independently flows into the splenic vein (N = 3, 3.1%); (type 4V) the SFV is absent (N = 24, 25.0%).
CONCLUSIONS: 3D-CTAC could reveal accurate preoperative tumor localization and vascular branching. These classifications should be helpful in performing accurate complete mesocolic excision and central vessel ligation for SFC.

OBJECTIVE. The purpose of this study was to evaluate the accuracy of CT colonography (CTC) in the diagnosis of synchronous colonic lesions in a cohort of patients with an occlusive colorectal cancer (CRC) causing incomplete colonoscopy. SUBJECTS AND METHODS. Among 109 patients with CRC causing incomplete colonoscopy who underwent CTC with IV contrast enhancement after cathartic purgation, fecal tagging, and colon distention, 70 (mean age, 70 years) for whom reference standards (surgical reports, first surveillance colonoscopy) were available were evaluated. Per-patient and per-lesion sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of CTC in the diagnosis of synchronous colonic lesions measuring 6 mm or larger were assessed. RESULTS. Twenty-seven of the 70 patients (39%) had at least one 6-mm or larger synchronous lesion, and four patients (6%) had a total of five synchronous CRCs. Per-patient sensitivity in diagnosing synchronous CRC was 1.00 (4/4). There were 59 lesions: 20 with a diameter of 10 mm or greater; 30, 6-9 mm; and nine, 5 mm or less. The overall per-patient CTC sensitivity in detecting synchronous lesions 6 mm or larger was 0.93 (25/27); specificity, 0.98 (42/43); PPV, 0.96; and NPV, 0.95. Per-patient sensitivity for the diagnosis of synchronous advanced neoplasia (advanced adenoma and colorectal cancers) was 0.94 (15/16). Per-lesion CTC sensitivity for detecting synchronous lesions 6 mm or larger was 0.88 (37/42); all adenomatous lesions, 0.89 (55/62); and advanced neoplasia, 0.92 (22/24). CONCLUSION. CTC is a highly accurate test for detecting synchronous colonic lesions in patients with occlusive CRC. The prevalence of advanced neoplasia is high (23%).