Patients' experience of screening CT colonography with reduced and full bowel preparation in a randomised trial.

OBJECTIVES: To assess patients' experience of bowel preparation and procedure for screening CT colonography with reduced (r-CTC) and full cathartic preparation (f-CTC) that showed similar detection rate for advanced neoplasia in a randomised trial. METHODS: Six hundred seventy-four subjects undergoing r-CTC and 612 undergoing f-CTC in the SAVE trial were asked to complete two pre-examination questionnaires-(1) Life Orientation Test - Revised (LOT-R) assessing optimism and (2) bowel preparation questionnaire-and a post-examination questionnaire evaluating overall experience of CTC screening test. Items were analysed with chi-square and t test separately and pooled. RESULTS: LOT-R was completed by 529 (78%) of r-CTC and by 462 (75%) of f-CTC participants and bowel preparation questionnaire by 531 (79%) subjects in the r-CTC group and by 465 (76%) in the f-CTC group. Post-examination questionnaire was completed by 525 (78%) subjects in the r-CTC group and by 453 (74%) in the f-CTC group. LOT-R average score was not different between r-CTC (14.27 ± 3.66) and f-CTC (14.54 ± 3.35) (p = 0.22). In bowel preparation questionnaire, 88% of r-CTC subjects reported no preparation-related symptoms as compared to 70% of f-CTC subjects (p < 0.001). No interference of bowel preparation with daily activities was reported in 80% of subjects in the r-CTC group as compared to 53% of subjects in the f-CTC group (p < 0.001). In post-examination questionnaire, average scores for discomfort of the procedure were not significantly different between r-CTC (3.53 ± 0.04) and f-CTC (3.59 ± 0.04) groups (p = 0.84). CONCLUSIONS: Reduced bowel preparation is better tolerated than full preparation for screening CT colonography. KEY POINTS: • Reduced bowel preparation is better tolerated than full preparation for screening CT colonography. • Procedure-related discomfort of screening CT colonography is not influenced by bowel preparation. • Males tolerate bowel preparation and CT colonography screening procedure better than females.

Computer-based self-training for CT colonography with and without CAD.

OBJECTIVES: To determine whether (1) computer-based self-training for CT colonography (CTC) improves interpretation performance of novice readers; (2) computer-aided detection (CAD) use during training affects learning. METHODS: Institutional review board approval and patients' informed consent were obtained for all cases included in this study. Twenty readers (17 radiology residents, 3 radiologists) with no experience in CTC interpretation were recruited in three centres. After an introductory course, readers performed a baseline assessment test (37 cases) using CAD as second reader. Then they were randomized (1:1) to perform either a computer-based self-training (150 cases verified at colonoscopy) with CAD as second reader or the same training without CAD. The same assessment test was repeated after completion of the training programs. Main outcome was per lesion sensitivity (≥ 6 mm). A generalized estimating equation model was applied to evaluate readers' performance and the impact of CAD use during training. RESULTS: After training, there was a significant improvement in average per lesion sensitivity in the unassisted phase, from 74% (356/480) to 83% (396/480) (p < 0.001), and in the CAD-assisted phase, from 83% (399/480) to 87% (417/480) (p = 0.021), but not in average per patient sensitivity, from 93% (390/420) to 94% (395/420) (p = 0.41), and specificity, from 81% (260/320) to 86% (276/320) (p = 0.15). No significant effect of CAD use during training was observed on per patient sensitivity and specificity, nor on per lesion sensitivity. CONCLUSIONS: A computer-based self-training program for CTC improves readers' per lesion sensitivity. CAD as second reader does not have a significant impact on learning if used during training. KEY POINTS: • Computer-based self-training for CT colonography improves per lesion sensitivity of novice readers. • Self-training program does not increase per patient specificity of novice readers. • CAD used during training does not have significant impact on learning.

CT Colonography Performance for the Detection of Polyps and Cancer in Adults ≥ 65 Years Old: Systematic Review and Meta-Analysis.

OBJECTIVE: We sought to perform a systematic review and meta-analysis of published CT colonography (CTC) studies assessing lesion detection in senior-age (≥ 65 years old) cohorts. MATERIALS AND METHODS: We conducted a systematic review of CTC studies published between January 1994 and August 2017 containing data on senior-age adults. The primary endpoint was the CTC-positive rate for large colorectal polyps (≥ 10 mm) and masses. Secondary endpoints included lesions ≥ 6 mm, proven advanced neoplasia, and colorectal cancer (CRC). Study authors were contacted for additional missing data. Random-effects and meta-regression analyses were used to generate pooled estimates and explore contributing factors. RESULTS: A total of 34 studies with 41,680 (18,798 senior-age) subjects were included. Pooled CTC-positive rates among senior-age patients using the 10-mm size threshold were significantly lower in cohorts of patients with no symptoms (8.2%; 95% CI, 6.0-11.1%) compared with cohorts of patients with positive fecal occult blood tests (32.8%; 95% CI, 15.4-56.7%) and other symptoms of CRC (14.0%; 95% CI, 12.0-16.1%). However, a uniformly high positive predictive value for advanced neoplasia at colonoscopy was seen for all senior-age cohorts using a 10-mm threshold (84.3%; 95% CI, 79.3-88.3%; I2 = 0.0) where such data were available. CTC sensitivity for CRC was 93.0% (95% CI, 89.0-95.0%) in senior-age patients compared with 92.0% (95% CI, 84.0-93.0%) in younger patients. Overall, CTC detection rates were higher in senior-age adults compared with younger adults. CONCLUSION: On average, one in every 12 senior-age adults without symptoms of CRC who underwent screening would be referred to colonoscopy using the 10-mm threshold, with a high yield for advanced neoplasia and high sensitivity for cancer detection. As expected, CTC-positive rates were higher in cohorts of patients 65 years old or older with symptoms of CRC. These results should help inform the Centers for Medicare & Medicaid Services regarding coverage determination of CTC screening for Medicare beneficiaries.

Breast Cancer: Computer-aided Detection with Digital Breast Tomosynthesis.

PURPOSE: To evaluate a commercial tomosynthesis computer-aided detection (CAD) system in an independent, multicenter dataset. MATERIALS AND METHODS: Diagnostic and screening tomosynthesis mammographic examinations (n = 175; cranial caudal and mediolateral oblique) were randomly selected from a previous institutional review board-approved trial. All subjects gave informed consent. Examinations were performed in three centers and included 123 patients, with 132 biopsy-proven screening-detected cancers, and 52 examinations with negative results at 1-year follow-up. One hundred eleven lesions were masses and/or microcalcifications (72 masses, 22 microcalcifications, 17 masses with microcalcifications) and 21 were architectural distortions. Lesions were annotated by radiologists who were aware of all available reports. CAD performance was assessed as per-lesion sensitivity and false-positive results per volume in patients with negative results. RESULTS: Use of the CAD system showed per-lesion sensitivity of 89% (99 of 111; 95% confidence interval: 81%, 94%), with 2.7 ± 1.8 false-positive rate per view, 62 of 72 lesions detected were masses, 20 of 22 were microcalcification clusters, and 17 of 17 were masses with microcalcifications. Overall, 37 of 39 microcalcification clusters (95% sensitivity, 95% confidence interval: 81%, 99%) and 79 of 89 masses (89% sensitivity, 95% confidence interval: 80%, 94%) were detected with the CAD system. On average, 0.5 false-positive rate per view were microcalcification clusters, 2.1 were masses, and 0.1 were masses and microcalcifications. CONCLUSION: A digital breast tomosynthesis CAD system can allow detection of a large percentage (89%, 99 of 111) of breast cancers manifesting as masses and microcalcification clusters, with an acceptable false-positive rate (2.7 per breast view). Further studies with larger datasets acquired with equipment from multiple vendors are needed to replicate the findings and to study the interaction of radiologists and CAD systems.

Comparison of three different iodine-based bowel regimens for CT colonography.

OBJECTIVE: The aim of this study was to compare the computed tomographic colonography (CTC) image quality and patient acceptance of three iodine-based faecal tagging bowel preparations in 60 patients undergoing the following regimens: a 2-day regimen of meal-time administration of iodine and phospho-soda (GFPH); a 2-day regimen of meal-time mild laxative, followed by iodine administered 2 h before CTC (SD); and a 2-day regimen of meal-time administration of iodine (GF). METHODS: Two independent radiologists assessed tagging quality; quantitative measures included the tagged stool density, and computer-aided detection (CAD) false-positive rate. RESULTS: The GFPH and SD regimens provided better subjective quality than GF (p < 0.001). The latter regimen resulted in a higher proportion of insufficiently tagged segments: the measured average stool density was less than 200 HU in 10.7% in all segments vs 3.6% for SD and <0.5% for GFPH, respectively. Insufficient tagging occurred mostly in the ascending colon and the caecum. The CAD false-positive rate increased following the trend: GFPH < SD < GF (p = 0.00012). GFPH was worse tolerated than SD (p < 0.05). CONCLUSIONS: Considering preparation quality alone, GFPH was the best regimen, but SD provided the best balance between bowel preparation quality and patient acceptability.

Faecal immunochemical test in subjects not attending screening computed tomography colonography and colonoscopy in a randomized trial.

The aim of this study was to evaluate the participation and yield of the faecal immunochemical test (FIT) in nonattendees for computed tomography colonography (CTC) or optical colonoscopy (OC) screening, in the setting of a randomized trial. In the SAVE trial, 16087 individuals were randomly assigned and invited to one of four interventions for colorectal cancer screening: (i) biennial FIT for three rounds; (ii) reduced-preparation CTC; (iii) full-preparation CTC; and (iv) OC. Nonattendees of reduced-preparation CTC, full-preparation CTC and OC groups were invited to FIT. Here, we analysed the participation rate and the detection rate for cancer or advanced adenoma (advanced neoplasia) of FIT among nonattendees for reduced-preparation CTC, full-preparation CTC and OC. Nonattendees were 1721 of 2395 (71.9%) eligible invitees in the reduced-preparation CTC group, 1818 of 2430 (74.8%) in the full-preparation CTC group and 883 of 1036 (85.2%) in the OC group. Participation rates for FIT were 20.2% (347/1721) in nonattendees for reduced-preparation CTC, 21.4% (389/1818) in nonattendees for full-preparation CTC and 25.8% (228/883) in nonattendees for OC. Differences between both CTC groups and the OC group were statistically significant (P≤0.01), whereas the difference between reduced-preparation and full-preparation CTC groups was not statistically significant (P=0.38). The detection rate of FIT was not statistically significantly different among nonattendees for reduced-preparation CTC (0.9%; 3/347), nonattendees for full-preparation CTC (1.8%; 7/389) and nonattendees for OC (1.3%; 3/228) (P>0.05). Offering FIT to nonattendees for CTC or OC increases the overall participation in colorectal cancer screening and enables the detection of additional advanced neoplasia.

Cost analysis of colorectal cancer screening with CT colonography in Italy.

OBJECTIVE: Unit costs of screening CT colonography (CTC) can be useful for cost-effectiveness analyses and for health care decision-making. We evaluated the unit costs of CTC as a primary screening test for colorectal cancer in the setting of a randomized trial in Italy. METHODS: Data were collected within the randomized SAVE trial. Subjects were invited to screening CTC by mail and requested to have a pre-examination consultation. CTCs were performed with 64- and 128-slice CT scanners after reduced or full bowel preparation. Activity-based costing was used to determine unit costs per-process, per-participant to screening CTC, and per-subject with advanced neoplasia. RESULTS: Among 5242 subjects invited to undergo screening CTC, 1312 had pre-examination consultation and 1286 ultimately underwent CTC. Among 129 subjects with a positive CTC, 126 underwent assessment colonoscopy and 67 were ultimately diagnosed with advanced neoplasia (i.e., cancer or advanced adenoma). Cost per-participant of the entire screening CTC pathway was €196.80. Average cost per-participant for the screening invitation process was €17.04 and €9.45 for the pre-examination consultation process. Average cost per-participant of the CTC execution and reading process was €146.08 and of the diagnostic assessment colonoscopy process was €24.23. Average cost per-subject with advanced neoplasia was €3777.30. CONCLUSIONS: Cost of screening CTC was €196.80 per-participant. Our data suggest that the more relevant cost of screening CTC, amenable of intervention, is related to CTC execution and reading process.

Reduced and Full-Preparation CT Colonography, Fecal Immunochemical Test, and Colonoscopy for Population Screening of Colorectal Cancer: A Randomized Trial.

BACKGROUND: Population screening for colorectal cancer (CRC) is widely adopted, but the preferred strategy is still under debate. We aimed to compare reduced (r-CTC) and full cathartic preparation CT colonography (f-CTC), fecal immunochemical test (FIT), and optical colonoscopy (OC) as primary screening tests for CRC. METHODS: Citizens of a district of Florence, Italy, age 54 to 65 years, were allocated (8:2.5:2.5:1) with simple randomization to be invited by mail to one of four screening interventions: 1) biennial FIT for three rounds, 2) r-CTC, 3) f-CTC, 4) OC. Patients tested positive to FIT or CTC (at least one polyp ≥6mm) were referred to OC work-up. The primary outcomes were participation rate and detection rate (DR) for cancer or advanced adenoma (advanced neoplasia). All statistical tests were two-sided. RESULTS: Sixteen thousand eighty-seven randomly assigned subjects were invited to the assigned screening test. Participation rates were 50.4% (4677/9288) for first-round FIT, 28.1% (674/2395) for r-CTC, 25.2% (612/2430) for f-CTC, and 14.8% (153/1036) for OC. All differences between groups were statistically significant (P = .047 for r-CTC vs f-CTC; P < .001 for all others). DRs for advanced neoplasia were 1.7% (79/4677) for first-round FIT, 5.5% (37/674) for r-CTC, 4.9% (30/612) for f-CTC, and 7.2% (11/153) for OC. Differences in DR between CTC groups and FIT were statistically significant (P < .001), but not between r-CTC and f-CTC (P = .65). CONCLUSIONS: Reduced preparation increases participation in CTC. Lower attendance and higher DR of CTC as compared with FIT are key factors for the optimization of its role in population screening of CRC.

Evaluation of computer-aided detection and diagnosis systems.

Computer-aided detection and diagnosis (CAD) systems are increasingly being used as an aid by clinicians for detection and interpretation of diseases. Computer-aided detection systems mark regions of an image that may reveal specific abnormalities and are used to alert clinicians to these regions during image interpretation. Computer-aided diagnosis systems provide an assessment of a disease using image-based information alone or in combination with other relevant diagnostic data and are used by clinicians as a decision support in developing their diagnoses. While CAD systems are commercially available, standardized approaches for evaluating and reporting their performance have not yet been fully formalized in the literature or in a standardization effort. This deficiency has led to difficulty in the comparison of CAD devices and in understanding how the reported performance might translate into clinical practice. To address these important issues, the American Association of Physicists in Medicine (AAPM) formed the Computer Aided Detection in Diagnostic Imaging Subcommittee (CADSC), in part, to develop recommendations on approaches for assessing CAD system performance. The purpose of this paper is to convey the opinions of the AAPM CADSC members and to stimulate the development of consensus approaches and "best practices" for evaluating CAD systems. Both the assessment of a standalone CAD system and the evaluation of the impact of CAD on end-users are discussed. It is hoped that awareness of these important evaluation elements and the CADSC recommendations will lead to further development of structured guidelines for CAD performance assessment. Proper assessment of CAD system performance is expected to increase the understanding of a CAD system's effectiveness and limitations, which is expected to stimulate further research and development efforts on CAD technologies, reduce problems due to improper use, and eventually improve the utility and efficacy of CAD in clinical practice.

Noise estimation in infrared image sequences: a tool for the quantitative evaluation of the effectiveness of registration algorithms.

Dynamic infrared imaging has been proposed in literature as an adjunctive technique to mammography in breast cancer diagnosis. It is based on the acquisition of hundreds of consecutive thermal images with a frame rate ranging from 50 to 200 frames/s, followed by the harmonic analysis of temperature time series at each image pixel. However, the temperature fluctuation due to blood perfusion, which is the signal of interest, is small compared to the signal fluctuation due to subject movements. Hence, before extracting the time series describing temperature fluctuations, it is fundamental to realign the thermal images to attenuate motion artifacts. In this paper, we describe a method for the quantitative evaluation of any kind of feature-based registration algorithm on thermal image sequences, provided that an estimation of local velocities of reference points on the skin is available. As an example of evaluation of a registration algorithm, we report the evaluation of the SNR improvement obtained by applying a nonrigid piecewise linear algorithm.

Evaluation of feature-based registration in dynamic infrared imaging for breast cancer diagnosis.

Dynamic infrared imaging has been proposed in literature as an interesting adjunctive technique to mammography in breast cancer diagnosis. For a correct analysis of the infrared image sequences, however, a preprocessing registration step may be fundamental. In this paper, we provide a first quantitative evaluation of the performances of registration on dynamic infrared images for this specific application. We propose an algorithm for the automatic control point localization and employ a feature-based piecewise linear registration approach. The quality of the image alignment is evaluated on a small sample of subjects, considering both alignment and localization errors. Results show that subject movement of up to five pixels is compensated, obtaining a subpixel error correction.

User-independent plaque characterization and accurate IMT measurement of carotid artery wall using ultrasound.

Non-invasive plaque characterization of the carotid wall is crucial for the early assessment of pathology, as well as for the monitoring of the progression of a degenerative phenomenon. Specifically, in clinical practice the carotid wall status is assessed by means of B-Mode ultrasound scans. We recently implemented an algorithm for the segmentation of the common tract of the carotid wall using ultrasound relative to healthy subjects. This paper presents a superior strategy for plaque characterization, which accurately determines both echolucent-type II and echogenic plaques in pathologic subjects. We preserve both user-independence and pixel fuzziness in our approach, thereby designing an accurate intima-media thickness (IMT). Our database consists of 20 subjects comprising of normal, stable (echogenic) and unstable (echolucent) plaques. In this database of 45 images, we demonstrate our performance with respect to the gold standard tracings to an accuracy determined as normalized error to be about 8%. The results are very promising and this algorithm is being integrated into clinical setup for automatic pathologic carotid wall analysis.

CULEX-completely user-independent layers extraction: ultrasonic carotid artery images segmentation.

The analysis of the carotid wall is of paramount importance in clinical practice. In fact, the intima-media thickness is a risk index for some of the most severe acute cerebrovascular pathologies; hence, the need for an accurate segmentation of the different layers of the carotid artery. In the past ten years, a wide variety of algorithms for the carotid tunica segmentation have been proposed, but they require a certain degree of user interaction. In this paper we propose a novel approach to the completely user-independent segmentation of the carotid artery wall. Our algorithm has been designed for the extraction of the intima and media layers of the distal carotid wall, based on ultrasonic B-Mode images. We evaluated the performance of the algorithm on a set of 63 images and compared the automatic segmentation to that traced by a trained operator. We obtained a mean error lower than 1.3 pixel both on the intima and media layers, which is comparable to that obtained by means of operator dependent techniques.