Contrast media for hysterosalpingography: systematic search and review providing new guidelines by the Contrast Media Safety Committee of the European Society of Urogenital Radiology.

OBJECTIVES: Hysterosalpingography (HSG) is widely used for evaluating the fallopian tubes; however, controversies regarding the use of water- or oil-based iodine-based contrast media (CM) remain. The aim of this work was (1) to discuss reported pregnancy rates related to the CM type used, (2) to validate the used CM in published literature, (3) to discuss possible complications and side effects of CM in HSG, and (4) to develop guidelines on the use of oil-based CM in HSG. METHODS: A systematic literature search was conducted for original RCT studies or review/meta-analyses on using water-based and oil-based CM in HSG with fertility outcomes and complications. Nine randomized controlled trials (RCTs) and 10 reviews/meta-analyses were analyzed. Grading of the literature was performed based on the Oxford Centre for Evidence-Based Medicine (OCEBM) 2011 classification. RESULTS: An approximately 10% higher pregnancy rate is reported for oil-based CM. Side effects are rare, but oil-based CM have potentially more side effects on the maternal thyroid function and the peritoneum. CONCLUSIONS: 1. HSG with oil-based CM gives approximately 10% higher pregnancy rates. 2. External validity is limited, as in five of nine RCTs, the CM used is no longer on the market. 3. Oil-based CM have potentially more side effects on the maternal thyroid function and on the peritoneum. 4. Guideline: Maternal thyroid function should be tested before HSG with oil-based CM and monitored for 6 months after. CLINICAL RELEVANCE STATEMENT: Oil-based CM is associated with an approximately 10% higher chance of pregnancy compared to water-based CM after HSG. Although side effects are rare, higher iodine concentration and slower clearance of oil-based CM may induce maternal thyroid function disturbance and peritoneal inflammation and granuloma formation. KEY POINTS: • It is unknown which type of contrast medium, oil-based or water-based, is the optimal for HSG. • Oil-based contrast media give a 10% higher chance of pregnancy after HSG, compared to water-based contrast media. • From the safety perspective, oil-based CM can cause thyroid dysfunction and an intra-abdominal inflammatory response in the patient.

A prediction model for lung metastases in patients with indeterminate pulmonary nodules in newly diagnosed colorectal cancer.

INTRODUCTION: Multidisciplinary teams treating patients with newly diagnosed Colorectal Cancer (CRC) often encounter the appearance of Indeterminate Pulmonary Nodules (IPNs) that warrants follow-up with repetitive medical imaging and anxiety for patients. We determined the incidence of IPNs in patients with newly diagnosed CRC and developed and validated a model for individualized risk prediction of IPNs being lung metastases. MATERIAL AND METHODS: Newly diagnosed CRC who underwent surgery between November 2011 to June 2014 were included to create the risk model, developed using both clinical experience and statistical selection. Discrimination and calibration slopes of the risk score were evaluated in an independent temporal validation sample. A nomogram is presented to assist clinicians in estimating an individual risk score. RESULTS: Out of 2111 CRC patients staged with chest CT, 204 (9.6%) had IPNs and 54/204 (26%) had lung metastases. We identified 4 predictors: "location of primary tumour", "pathological nodal stage", "size of the largest nodule" and "extrapulmonary synchronous metastases at diagnosis". Discrimination of the final model in the validation sample was demonstrated by the difference in mean predicted risk between progressed cases en non-progressed cases (49% versus 21%, p = <0.001). CONCLUSION: A prediction model with 4 clinical risk factors can be used to assist multidisciplinary teams in the prediction of individualized risk of lung metastases and imaging strategy in patients with IPNs and newly diagnosed colorectal cancer. The model performed well in new patients not included in the model development.

Analytical interference of intravascular contrast agents with clinical laboratory tests: a joint guideline by the ESUR Contrast Media Safety Committee and the Preanalytical Phase Working Group of the EFLM Science Committee.

The Contrast Media Safety Committee of the European Society of Urogenital Radiology has, together with the Preanalytical Phase Working Group of the EFLM Science Committee, reviewed the literature and updated its recommendations to increase awareness and provide insight into these interferences.

Waiting times between examinations with intravascularly administered contrast media: a review of contrast media pharmacokinetics and updated ESUR Contrast Media Safety Committee guidelines.

The pharmacokinetics of contrast media (CM) will determine how long safe waiting intervals between successive CT or MRI examinations should be. The Contrast Media Safety Committee has reviewed the data on pharmacokinetics of contrast media to suggest safe waiting intervals between successive contrast-enhanced imaging studies in relation to the renal function of the patient. CLINICAL RELEVANCE STATEMENT: Consider a waiting time between elective contrast-enhanced CT and (coronary) angiography with successive iodine-based contrast media administrations in patients with normal renal function (eGFR > 60 mL/min/1.73 m2) of optimally 12 h (near complete clearance of the previously administered iodine-based contrast media) and minimally 4 h (if clinical indication requires rapid follow-up). KEY POINTS: • Pharmacokinetics of contrast media will guide safe waiting times between successive administrations. • Safe waiting times increase with increasing renal insufficiency. • Iodine-based contrast media influence MRI signal intensities and gadolinium-based contrast agents influence CT attenuation.

Safe use of contrast media in myasthenia gravis: systematic review and updated European Society of Urogenital Radiology Contrast Media Safety Committee guidelines.

OBJECTIVES: It is uncertain whether modern iodine-based or gadolinium-based contrast media (CM) administration can lead to increased symptoms in patients with myasthenia gravis. METHODS: A systematic search in Medline was conducted for studies describing the symptomatology of myasthenia gravis patients before and after receiving intravenous (IV) CM and having a matched control group of myasthenia gravis patients who did not receive IV CM. RESULTS: Three retrospective studies were selected with a total of 374 myasthenia gravis patients who received iodine-based CM and a total of 313 myasthenia gravis patients who underwent unenhanced CT and served as controls. Pooling of the data from the three retrospective studies showed that in 23 of 374 patients, increased symptoms after iodine-based CM administration were described (6.1%). Increased symptomatology also occurred in 11 of 313 patients after unenhanced CT (3.5%). When looking more deeply into the data of the three studies, conflicting results were found, as two articles did not find any relationship between CM and myasthenia gravis symptoms. The remaining study only found a significant increase in symptomatology within 1 day after CT scanning: seven patients (6.3%) in the contrast-enhanced CT group and one patient (0.6%) in the unenhanced CT group (p = 0.01). CONCLUSIONS: There is limited evidence on the relationship between CM and myasthenia gravis symptoms. In the vast majority of myasthenia gravis patients, CM are safe. Probably, in less than 5% of the patients, iodine-based CM administration may lead to increased severity of the symptoms within the first 24 h after administration. CLINICAL RELEVANCE STATEMENT: Be aware that intravenous administration of iodine-based contrast media can lead to an increase of symptoms in patients with myasthenia gravis within the first 24 h. This can probably happen in less than 5% of the patients. KEY POINTS: • It is unclear whether modern contrast media can lead to increased symptoms in myasthenia gravis patients after intravenous administration. • There seems to be a small risk of increased myasthenia gravis symptoms within 24 h after intravenous administration of iodine-based contrast media, probably in less than 5% of the administrations. • Gadolinium-based contrast media are safe for patients with myasthenia gravis.

Analytical interference of intravascular contrast agents with clinical laboratory tests: a joint guideline by the ESUR Contrast Media Safety Committee and the Preanalytical Phase Working Group of the EFLM Science Committee.

The Contrast Media Safety Committee of the European Society of Urogenital Radiology has, together with the Preanalytical Phase Working Group of the EFLM Science Committee, reviewed the literature and updated its recommendations to increase awareness and provide insight into these interferences. CLINICAL RELEVANCE STATEMENT: Contrast Media may interfere with clinical laboratory tests. Awareness of potential interference may prevent unwanted misdiagnosis. KEY POINTS: • Contrast Media may interfere with clinical laboratory tests; therefore awareness of potential interference may prevent unwanted misdiagnosis. • Clinical Laboratory tests should be performed prior to radiological imaging with contrast media or alternatively, blood or urine collection should be delayed, depending on kidney function.

Development and multicenter validation of a multiparametric imaging model to predict treatment response in rectal cancer.

OBJECTIVES: To develop and validate a multiparametric model to predict neoadjuvant treatment response in rectal cancer at baseline using a heterogeneous multicenter MRI dataset. METHODS: Baseline staging MRIs (T2W (T2-weighted)-MRI, diffusion-weighted imaging (DWI) / apparent diffusion coefficient (ADC)) of 509 patients (9 centres) treated with neoadjuvant chemoradiotherapy (CRT) were collected. Response was defined as (1) complete versus incomplete response, or (2) good (Mandard tumor regression grade (TRG) 1-2) versus poor response (TRG3-5). Prediction models were developed using combinations of the following variable groups: (1) Non-imaging: age/sex/tumor-location/tumor-morphology/CRT-surgery interval (2) Basic staging: cT-stage/cN-stage/mesorectal fascia involvement, derived from (2a) original staging reports, or (2b) expert re-evaluation (3) Advanced staging: variables from 2b combined with cTN-substaging/invasion depth/extramural vascular invasion/tumor length (4) Quantitative imaging: tumour volume + first-order histogram features (from T2W-MRI and DWI/ADC) Models were developed with data from 6 centers (n = 412) using logistic regression with the Least Absolute Shrinkage and Selector Operator (LASSO) feature selection, internally validated using repeated (n = 100) random hold-out validation, and externally validated using data from 3 centers (n = 97). RESULTS: After external validation, the best model (including non-imaging and advanced staging variables) achieved an area under the curve of 0.60 (95%CI=0.48-0.72) to predict complete response and 0.65 (95%CI=0.53-0.76) to predict a good response. Quantitative variables did not improve model performance. Basic staging variables consistently achieved lower performance compared to advanced staging variables. CONCLUSIONS: Overall model performance was moderate. Best results were obtained using advanced staging variables, highlighting the importance of good-quality staging according to current guidelines. Quantitative imaging features had no added value (in this heterogeneous dataset). CLINICAL RELEVANCE STATEMENT: Predicting tumour response at baseline could aid in tailoring neoadjuvant therapies for rectal cancer. This study shows that image-based prediction models are promising, though are negatively affected by variations in staging quality and MRI acquisition, urging the need for harmonization. KEY POINTS: This multicenter study combining clinical information and features derived from MRI rendered disappointing performance to predict response to neoadjuvant treatment in rectal cancer. Best results were obtained with the combination of clinical baseline information and state-of-the-art image-based staging variables, highlighting the importance of good quality staging according to current guidelines and staging templates. No added value was found for quantitative imaging features in this multicenter retrospective study. This is likely related to acquisition variations, which is a major problem for feature reproducibility and thus model generalizability.

Patients with Clinically Suspected Gallstone Disease: A More Selective Ultrasound May Improve Treatment Related Outcomes.

This study aimed to quantify the confirmation of gallstones on ultrasound (US) in patients with suspicion of gallstone disease. To aid general practitioners (GPs) in diagnostic workup, a model to predict gallstones was developed. A prospective cohort study was conducted in two Dutch general hospitals. Patients (≥18 years) were eligible for inclusion when referred by GPs for US with suspicion of gallstones. The primary outcome was the confirmation of gallstones on US. A multivariable regression model was developed to predict the presence of gallstones. In total, 177 patients were referred with a clinical suspicion of gallstones. Gallstones were found in 64 of 177 patients (36.2%). Patients with gallstones reported higher pain scores (VAS 8.0 vs. 6.0, p < 0.001), less frequent pain (21.9% vs. 54.9%, p < 0.001), and more often met criteria for biliary colic (62.5% vs. 44.2%, p = 0.023). Predictors for the presence of gallstones were a higher pain score, frequency of pain less than weekly, biliary colic, and an absence of heartburn. The model showed good discrimination between patients with and without gallstones (C-statistic 0.73, range: 0.68-0.76). Clinical diagnosis of symptomatic gallstone disease is challenging. The model developed in this study may aid in the selection of patients for referral and improve treatment related outcomes.

Intravenous contrast medium extravasation: systematic review and updated ESUR Contrast Media Safety Committee Guidelines.

NEED FOR A REVIEW: Guidelines for management and prevention of contrast media extravasation have not been updated recently. In view of emerging research and changing working practices, this review aims to inform update on the current guidelines. AREAS COVERED: In this paper, we review the literature pertaining to the pathophysiology, diagnosis, risk factors and treatments of contrast media extravasation. A suggested protocol and guidelines are recommended based upon the available literature. KEY POINTS: • Risk of extravasation is dependent on scanning technique and patient risk factors. • Diagnosis is mostly clinical, and outcomes are mostly favourable. • Referral to surgery should be based on clinical severity rather than extravasated volume.

Evolutions in rectal cancer MRI staging and risk stratification in The Netherlands.

PURPOSE: To analyze how the MRI reporting of rectal cancer has evolved (following guideline updates) in The Netherlands. METHODS: Retrospective analysis of 712 patients (2011-2018) from 8 teaching hospitals in The Netherlands with available original radiological staging reports that were re-evaluated by a dedicated MR expert using updated guideline criteria. Original reports were classified as "free-text," "semi-structured," or "template" and completeness of reporting was documented. Patients were categorized as low versus high risk, first based on the original reports (high risk = cT3-4, cN+, and/or cMRF+) and then based on the expert re-evaluations (high risk = cT3cd-4, cN+, MRF+, and/or EMVI+). Evolutions over time were studied by splitting the inclusion period in 3 equal time periods. RESULTS: A significant increase in template reporting was observed (from 1.6 to 17.6-29.6%; p < 0.001), along with a significant increase in the reporting of cT-substage, number of N+ and extramesorectal nodes, MRF invasion and tumor-MRF distance, EMVI, anal sphincter involvement, and tumor morphology and circumference. Expert re-evaluation changed the risk classification from high to low risk in 18.0% of cases and from low to high risk in 1.7% (total 19.7%). In the majority (17.9%) of these cases, the changed risk classification was likely (at least in part) related to use of updated guideline criteria, which mainly led to a reduction in high-risk cT-stage and nodal downstaging. CONCLUSION: Updated concepts of risk stratification have increasingly been adopted, accompanied by an increase in template reporting and improved completeness of reporting. Use of updated guideline criteria resulted in considerable downstaging (of mainly high-risk cT-stage and nodal stage).

Sources of variation in multicenter rectal MRI data and their effect on radiomics feature reproducibility.

OBJECTIVES: To investigate sources of variation in a multicenter rectal cancer MRI dataset focusing on hardware and image acquisition, segmentation methodology, and radiomics feature extraction software. METHODS: T2W and DWI/ADC MRIs from 649 rectal cancer patients were retrospectively acquired in 9 centers. Fifty-two imaging features (14 first-order/6 shape/32 higher-order) were extracted from each scan using whole-volume (expert/non-expert) and single-slice segmentations using two different software packages (PyRadiomics/CapTk). Influence of hardware, acquisition, and patient-intrinsic factors (age/gender/cTN-stage) on ADC was assessed using linear regression. Feature reproducibility was assessed between segmentation methods and software packages using the intraclass correlation coefficient. RESULTS: Image features differed significantly (p < 0.001) between centers with more substantial variations in ADC compared to T2W-MRI. In total, 64.3% of the variation in mean ADC was explained by differences in hardware and acquisition, compared to 0.4% by patient-intrinsic factors. Feature reproducibility between expert and non-expert segmentations was good to excellent (median ICC 0.89-0.90). Reproducibility for single-slice versus whole-volume segmentations was substantially poorer (median ICC 0.40-0.58). Between software packages, reproducibility was good to excellent (median ICC 0.99) for most features (first-order/shape/GLCM/GLRLM) but poor for higher-order (GLSZM/NGTDM) features (median ICC 0.00-0.41). CONCLUSIONS: Significant variations are present in multicenter MRI data, particularly related to differences in hardware and acquisition, which will likely negatively influence subsequent analysis if not corrected for. Segmentation variations had a minor impact when using whole volume segmentations. Between software packages, higher-order features were less reproducible and caution is warranted when implementing these in prediction models. KEY POINTS: • Features derived from T2W-MRI and in particular ADC differ significantly between centers when performing multicenter data analysis. • Variations in ADC are mainly (> 60%) caused by hardware and image acquisition differences and less so (< 1%) by patient- or tumor-intrinsic variations. • Features derived using different image segmentations (expert/non-expert) were reproducible, provided that whole-volume segmentations were used. When using different feature extraction software packages with similar settings, higher-order features were less reproducible.

Dealing with indeterminate pulmonary nodules in colorectal cancer patients; a systematic review.

INTRODUCTION: Indeterminate pulmonary nodules (IPNs) are frequently encountered on staging computed tomography (CT) in colorectal cancer (CRC) patients and they create diagnostic dilemmas. This systematic review and pooled analysis aims to estimate the incidence and risk of malignancy of IPNs and provide an overview of the existing literature on IPNs in CRC patients. MATERIALS AND METHODS: EMBASE, Pubmed and the Cochrane database were searched for papers published between January 2005 and April 2020. Studies describing the incidence of IPNs and the risk of malignancy in CRC patients and where the full text was available in the English language were considered for inclusion. Exclusion criteria included studies that used chest X-ray instead of CT, liver metastasis cohorts, studies with less than 60 CRC patients and reviews. RESULTS: A total of 18 studies met the inclusion criteria, involving 8637 patients. Pooled analysis revealed IPNs on staging chest CT in 1327 (15%) of the CRC patients. IPNs appeared to be metastatic disease during follow up in 16% of these patients. Regional lymph node metastases, liver metastases, location of the primary tumour in the rectum, larger IPN size and multiple IPNs are the five most frequently reported parameters predicting the risk of malignancy of IPNs. CONCLUSION: A risk stratification model for CRC patients with IPNs is warranted to enable an adequate selection of high risk patients for IPN follow up and to diminish the use of unnecessary repetitive chest CT-scans in the many low risk patients.

Four Weeks of Preoperative Omega-3 Fatty Acids Reduce Liver Volume: a Randomised Controlled Trial.

PURPOSE: Weight loss before bariatric surgery with a low-calorie diet (LCD) has several advantages, including reduction of liver volume and an improved access to the lesser sac. Disadvantages include performing surgery in a state of undernutrition, side effects, costs and patient compliance. Omega-3 fatty acids may serve as an alternative to reduce liver steatosis. MATERIALS AND METHODS: A randomised controlled open-label trial was done to compare the effects of a LCD with Modifast (800 kcal/day) during 2 weeks with 2 g of omega-3 fatty acids a day and a normal diet (2000 kcal/day) during 4 weeks. Total liver volume (TLV) and volume of the left liver lobe (LLL), visceral fat area (VFA) and muscle area (SMA) at the L3-L4 level were measured with MRI before and after preoperative treatment. RESULTS: Sixty-two morbidly obese women undergoing laparoscopic Roux-en-Y gastric bypass surgery (LRYGB) were recruited. In both groups, there was a significant decrease in LLL, TLV and VFA. For LLL and TLV reduction, the LCD had a significantly larger effect (p < 0.05). Only in the LCD group was there a significant decrease in SMA with significantly more side effects and worse compliance. CONCLUSION: Both the LCD and omega-3 diet reduced LLL, TLV and VFA. The LCD outperformed the omega-3 diet in LLL and TLV reduction, but induced significant loss of SMA and had worse compliance due to more side effects. Omega-3 fatty acids may provide a safe and more patient-friendly alternative for a LCD and further research is indicated. TRIAL REGISTRATION: The study is registered at www.clinicaltrials.gov (NCT02206256).

Ruling out coronary artery disease in women with atypical chest pain: results of calcium score combined with coronary computed tomography angiography and associated radiation exposure.

BACKGROUND: To assess the presence of coronary artery disease (CAD) in women with atypical chest pain with low or intermediate risk for significant CAD by means of calcium scoring (CaSc) combined with coronary computed tomography angiography (CCTA) and to estimate the equivalent radiation dose in women. PATIENTS AND METHODS: From December 2011 until July 2013, all consecutively performed cardiac CTs in women with atypical chest pain were included prospectively in the present study. Both CaSc and CCTA were obtained by a dual source flying focal spot 2×64 slice Somatom Definition Flash. Absence of CAD was defined as CaSc 0 and absence of noncalcified plaques. Presence of CAD was determined as CaSc>0 and/or presence of noncalcified plaques. The impact on patient management was also scored within our patient cohort. RESULTS: A total of 1033 procedures in 1014 women (mean age 59±10 years; mean BMI 26±8) were analyzed. In 520 (51%) women, CAD was absent. In 494 (49%) women, CAD was diagnosed, and in this subgroup the mean CaSc was 137±229. Thirty-seven (7%) of 494 women with CAD showed only noncalcified plaques. The mean equivalent radiation dose for the cardiac CTs of 1014 women was 2.2±1.6 mSv. CONCLUSION: Combined CaSc and CCTA excludes CAD in approximately 50% of women with atypical chest pain, and delivers a modest radiation dose of 2.2±1.6 mSv. CCTA has a substantial impact on patient management and can thus be advocated as first diagnostic tool in excluding CAD in women with atypical chest pain in terms of latest generation equipment with emphasize on radiation reduction techniques.

Pathophysiology of Contrast-Induced Acute Kidney Injury.

Contrast-induced acute kidney injury (CI-AKI) refers to acute kidney injury (AKI) after intravenous or intra-arterial administration of contrast media (CM). The 2 key mechanisms related to AKI are acute tubular necrosis and prerenal azotemia. Although the pathophysiology of AKI is complex, modern frameworks show that AKI has 3 major pathways: hemodynamic injury, systemic inflammation, and toxic injury. In the pathophysiology of CI-AKI, 3 major distinct, but potentially interacting pathways are recognized: hemodynamic effects, increase in oxygen free radicals, and direct CM molecule tubular cell toxicity. This article reviews the pathophysiology of CI-AKI by describing and explaining these pathways.

Contrast-induced nephropathy: pharmacology, pathophysiology and prevention.

Modern iodinated contrast media (CM) consist of one or two tri-iodobenzene rings. They differ from each other in the composition of the side chains, creating different molecules and thus different brand substances. After intravascular administration, all CM are distributed rapidly into intravascular and extracellular fluids. They are eliminated solely by glomerular filtration. In patients with normal renal function, CMs are eliminated within 24 h. The pathophysiology of contrast-induced nephropathy (CIN) is based on three distinct but interacting mechanisms: medullary ischaemia, formation of reactive oxygen species and direct tubular cell toxicity. The contribution of each of these mechanisms to the development of CIN in the individual patient remains unclear. CIN prevention is extensively described in guidelines, such as the recently updated guideline from the Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR). The recent update is briefly discussed. Furthermore, it remains unclear if volume expansion with either NaCl 0.9 % or NaHCO3 1.4 % is superior. Teaching points • After intravascular injection, CM are distributed over intravascular and extracellular fluids. • CM are eliminated by glomerular filtration in patients with normal kidney function. • CIN pathophysiology is based on medullary ischaemia, formation of reactive oxygen species (ROS) and tubular cell toxicity. • It remains unclear if volume expansion with either NaCl 0.9 % or NaHCO 3 1.4 % is superior.

Magnetic resonance imaging of the small bowel with the true FISP sequence: intra- and interobserver agreement of enteroclysis and imaging without contrast material.

PURPOSE: This study aimed to determine the reliability of magnetic resonance imaging (MRI) without luminal contrast medium versus MR enteroclysis for evaluating small bowel pathology, to compare MRI and MRE findings per observer, and to compare these findings with those of an expert reader in order to determine the influence of luminal contrast medium on morphological evaluations. CONCLUSION: The use of luminal contrast medium bowel improves reliability for measuring bowel wall thickness and for the diagnosis and grading of obstruction when evaluating the small bowel.

CT and MR colonography: scanning techniques, postprocessing, and emphasis on polyp detection.

In the last decade, computed tomographic (CT) and magnetic resonance (MR) colonography, two new cross-sectional techniques for imaging of the colon, emerged. Both techniques show promising initial results in the detection of polyps equal to or greater than 1 cm in diameter in symptomatic patients. Imaging protocols are still mostly under development and prone to change. Both CT and MR colonography generate a large number of source images, which have to be read carefully for filling defects and, if intravenous contrast material is used, enhancing lesions. An important postprocessing technique is multiplanar reformatting, which allows the viewer to see potential lesions in an orientation other than that of the source images. Virtual endoscopy, a volume rendering technique that generates images from within the colon lumen, is used for problem solving. CT and MR colonography have potential advantages over colonoscopy and double-contrast barium enema examination: multiplanar capabilities, detection of enhancing lesions that make the distinction between fecal residue and true lesion possible, and ante- and retrograde virtual colonoscopy. Currently, a number of studies suggest that patients have a preference for CT colonography over colonoscopy. Patients consider bowel cleansing the most uncomfortable part of any colon examination; hence, from the acceptance point of view, fecal tagging techniques are promising. Before CT and MR colonography can be implemented in daily practice, they must show approximately the same accuracy as colonoscopy for polyp detection in both symptomatic and screening patients.