Colorectal cancer is common. As many patients present with advanced disease, an effective screening test would have substantial clinical benefits. Recent progress in understanding the biology of colorectal cancer (and of cancer cells in general) has led to possible new approaches to screening. In particular, there are prospects of developing tests based on analysis of stool, which promise improved accuracy, safety, affordability and patient compliance.

Colorectal cancer screening: prospects for molecular stool analysis

OBJECTIVE. The purpose of our study was to perform a meta-analysis comparing the performance of double-contrast barium enema (DCBE) with CT colonography (CTC) for the detection of colorectal polyps ≥ 6 mm using endoscopy as the gold standard.MATERIALS AND METHODS. Prospective DCBE and CTC studies were identified. Percentages of polyps and of patients with polyps ≥ 10 mm and 6–9 mm were abstracted. The performance of DCBE versus CTC was determined by separately evaluating each technique's performance versus that of endoscopy, and contrasting the techniques. The I-squared statistic and Fisher's exact test were used for heterogeneity, the Cochran-Mantel-Haenszel and the Kruskal-Wallis tests for correlation, and the Az test for comparing pooled weighted estimates of performance.RESULTS. Eleven studies of DCBE (5,995 patients, 1,548 polyps) and 30 studies of CTC (6,573 patients, 2,348 polyps) fulfilled inclusion criteria. For polyps ≥ 10 mm, a 0.121-perpatient sensitivity difference favored CTC (p < 0.0001; DC...

Critical analysis of the performance of double-contrast barium enema for detecting colorectal polyps > or = 6 mm in the era of CT colonography.

Our purpose was to assess the effect of computer-aided detection (CAD) on lesion detection as a second reader in computed tomographic colonography, and to compare the influence of CAD on the performance of readers with different levels of expertise. Fifty-two CT colonography patient data-sets (37 patients: 55 endoscopically confirmed polyps ≥0.5 cm, seven cancers; 15 patients: no abnormalities) were retrospectively reviewed by four radiologists (two expert, two nonexpert). After primary data evaluation, a second reading augmented with findings of CAD (polyp-enhanced view, Siemens) was performed. Sensitivities and reading time were calculated for each reader without CAD and supported by CAD findings. The sensitivity of expert readers was 91% each, and of nonexpert readers, 76% and 75%, respectively, for polyp detection. CAD increased the sensitivity of expert readers to 96% (P = 0.25) and 93% (P = 1), and that of nonexpert readers to 91% (P = 0.008) and 95% (P = 0.001), respectively. All four readers diagnosed 100% of cancers, but CAD alone only 43%. CAD increased reading time by 2.1 min (mean). CAD as a second reader significantly improves sensitivity for polyp detection in a high disease prevalence population for nonexpert readers. CAD causes a modest increase in reading time. CAD is of limited value in the detection of cancer.

Effect of computer-aided detection as a second reader in multidetector-row CT colonography

This study investigated the variability in baseline computed tomography colonography (CTC) performance using untrained readers by documenting sources of error to guide future training requirements. Twenty CTC endoscopically validated data sets containing 32 polyps were consensus read by three unblinded radiologists experienced in CTC, creating a reference standard. Six readers without prior CTC training [four residents and two board-certified subspecialty gastrointestinal (GI) radiologists] read the 20 cases. Readers drew a region of interest (ROI) around every area they considered a potential colonic lesion, even if subsequently dismissed, before creating a final report. Using this final report, reader ROIs were classified as true positive detections, true negatives correctly dismissed, true detections incorrectly dismissed (i.e., classification error), or perceptual errors. Detection of polyps 1-5 mm, 6-9 mm, and > or =10 mm ranged from 7.1% to 28.6%, 16.7% to 41.7%, and 16.7% to 83.3%, respectively. There was no significant difference between polyp detection or false positives for the GI radiologists compared with residents (p=0.67, p=0.4 respectively). Most missed polyps were due to failure of detection rather than characterization (range 82-95%). Untrained reader performance is variable but generally poor. Most missed polyps are due perceptual error rather than characterization, suggesting basic training should focus heavily on lesion detection.

Reader error during CT colonography: causes and implications for training

With the introduction of multislice CT technology and faster gradients in MRI, CT and MR colonography are increasingly becoming attractive alternatives for colorectal mass screening. In this article we summarise the current status, research directions, and challenges in CT and MR colonography.

Colonography: current status, research directions and challenges. Update 2002.

Automation in colorectal mass detection is achieved as soon as the voxels representing colorectal masses can be automatically segmented. We tested the Hounsfield (HU) value in intensely contrast enhanced high-resolution CT colonography for automated segmentation of colorectal masses in 18 patients with 35 polyps (28<10 mm, 7 ≥10 mm) and 7 carcinomas. Mean HU values of the colonic wall and masses were determined to deduce a gradient threshold for a segmentation process, which encodes the voxels bordering the colonic lumen with a colour ranging in intensity from 0 to 100% according to the selected gradient threshold range in the volume rendering. The results of the automated segmentation process were superimposed on a virtual double contrast and endoscopic display and validated through correlation with morphology. Mean HU values and their standard deviations for the colonic wall, polyps <10 mm, polyps ≥10 mm and carcinomas were 63±24, 154±38, 116±41 and 108±29 HU, respectively. A gradient threshold ranging from 90 to 160 HU resulted in colour pools in 6 of 7 of polyps ≥10 mm, and 6 of 7 carcinomas that were significant enough to prospectively guide the reader's attention to these masses. Due to the superposition of "false-positive" voxels in the projection view, the virtual endoscopic perspective was superior to the virtual double contrast display for controlling the segmentation results. The HU value is promising for automated segmentation of colorectal masses but needs to be combined with morphological parameters to render automated colorectal mass detection more accurate. Further refinements of the method with subsequent analysis of its accuracy, as well as analogue studies with contrast-enhanced MRI, appear warranted. More information at http://www.multiorganscreening.org

Computer-aided diagnosis in contrast-enhanced CT colonography: an approach based on contrast.

Objective To compare different image reconstruction parameters for detecting emboli of the pulmonary arteries according to anatomic levels using 16-slice multidetector-row computed tomography in patients suspected of having an acute pulmonary embolism (PE). Methods Sixty-two patients (33 male and 29 female) with a clinically suspected acute PE were included in the present study. Multidetector-row computed tomography scans were performed using 16-mmx0.75-mm collimation. Based on the computed tomography data set, different image reconstruction parameters were used for each patient: axial slice thicknesses (STs) of 0.75, 2, 4, and 6 mm; axial maximum intensity projection (MIP) STs of 4 mm; and coronal STs of 2 and 4 mm. In joint reading fashion, 2 experienced radiologists reviewed examination findings regarding the presence and/or absence of a PE. The reference standard for visualization and detection of PEs was defined using the axial images with a 0.75-mm ST. Results In 23 of 62 patients, a PE was diagnosed. For main and lobar pulmonary arteries, the sensitivities and specificities were as follows: axial 2-mm images, 1.0/1.0; axial 4-mm images, 1.0/1.0; axial 6-mm images, 0.97/0.99; MIP 4-mm images, 0.95/0.99; coronal 2-mm images, 1.0/1.0; and coronal 4-mm images, 1.0/1.0. Regarding segmental and subsegmental pulmonary arteries, sensitivity and specificity varied: axial 2-mm images, 0.97/1.0; axial 4-mm images, 0.81/0.99; axial 6-mm images, 0.65/0.99; axial MIP 4-mm images, 0.63/0.99; coronal 2-mm images, 0.91/0.99; and coronal 4-mm images, 0.74/0.99. Conclusions In detecting segmental and subsegmental PEs, only the axial images with an ST of 2 mm proved to have results comparable with the axial 0.75-mm images. Therefore, thin-slice collimation and ST are mandatory for visualization of segmental and subsegmental PEs in patients suspected of having an acute PE.

Detection of pulmonary embolism using 16-slice multidetector-row computed tomography: evaluation of different image reconstruction parameters.


 
 
 Treatment with Tafamidis in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) has been shown to have beneficial effects on the left ventricle (LV), as assessed by cardiac magnetic resonance (CMR) imaging. Although CMR represents the gold standard among imaging modalities, its limited availability in clinical practice makes it unfeasible for routine therapy monitoring.
 
 
 
 We aimed to determine Tafamidis-induced changes using two-dimensional (2D) speckle-tracking echocardiography and to identify echocardiographic imaging parameters that could be used for specific therapy monitoring.
 
 
 
 We subjected a series of ATTR-CM patients to transthoracic echocardiography (TTE) at baseline and follow-up and compared patients treated with Tafamidis 61mg once daily (QD) to a historical control cohort treated with Tafamidis 20mg QD, as well as to a historical treatment-naïve control cohort reflecting the natural course of the disease.
 
 
 
 Patients receiving Tafamidis 61mg (n=62) or 20mg (n=21) QD showed stable measurements at follow-up [61mg: 8.5 months, 20mg: 7.0 months] in LV global longitudinal strain (GLS) (61mg: −11.75% vs. −11.58%, p=0.534; 20mg: −10.61% vs. −10.12%, p=0.309), right ventricular (RV) GLS (61mg: −14.18% vs. −13.72%, p=0.377; 20mg: −14.53% vs. −13.99%, p=0.452) and left atrial (LA) reservoir strain (LASr; 61mg: 8.80% vs. 9.42%, p=0.283; 20mg: 8.23% vs. 8.67%, p=0.589), whereas treatment-naïve ATTR-CM patients (n=54) had clear signs of disease progression at the end of the observation period [10.5 months; LV-GLS: −11.71% vs. −10.59%, p=0.001; RV-GLS: −14.36% vs. −12.99%, p=0.038; LASr: 10.67% vs. 8.41%, p=0.005]. Between-group comparison at follow-up revealed beneficial effects of Tafamidis 61mg on LASr (p=0.003), LV-GLS (p=0.030) and interventricular septum (IVS) thickness (p=0.006), resulting in clinical benefits (six-minute walk distance (6-MWD): p=0.006, NT-proBNP: p≤0.001), while patients treated with Tafamidis 20mg QD showed positive effects on LASr (p=0.039) but no differences in LV-GLS (p=0.274), IVS thickness (p=0.068) and clinical status (6-MWD: p=0.124, NT-proBNP: p=0.053) compared to the natural course.
 
 
 
 Treatment with Tafamidis 61mg in ATTR-CM patients delays the increase in IVS thickness and the deterioration of LA and LV longitudinal function, resulting in significant clinical benefits compared with natural history. Serial TTE with 2D speckle-tracking imaging may be appropriate for disease-specific therapy monitoring.
 
 
 
 Type of funding sources: Private company. Main funding source(s): This work was supported by the Pfizer Inc. However, Pfizer Inc. did not have influence on study design, data processing, or statistical analysis.


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Two-dimensional speckle-tracking echocardiography in tafamidis-treated patients with transthyretin amyloid cardiomyopathy: a glimmer of hope for viable therapy monitoring?

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Papers

Computer-aided diagnosis in contrast-enhanced CT colonography: an approach based on contrast.

Detection of pulmonary embolism using 16-slice multidetector-row computed tomography: evaluation of different image reconstruction parameters.

Two-dimensional speckle-tracking echocardiography in tafamidis-treated patients with transthyretin amyloid cardiomyopathy: a glimmer of hope for viable therapy monitoring?