Establishing a CT colonography service

A Systematic Approach of Data Collection and Analysis in Medical Imaging Research

Background:

Obtaining the right image dataset for the medical image research systematically is a tedious task. Anatomy segmentation is the key step before extracting the radiomic features from these images.

Objective:

The purpose of the study was to segment the 3D colon from CT images and to measure the smaller polyps using image processing techniques. This require huge number of samples for statistical analysis. Our objective was to systematically classify and arrange the dataset based on the parameters of interest so that the empirical testing becomes easier in medical image research.

Materials and Methods:

This paper discusses a systematic approach of data collection and analysis before using it for empirical testing. In this research the image were considered from National Cancer Institute (NCI). TCIA from NCI has a vast collection of diagnostic quality images for the research community. These datasets were classified before empirical testing of the research objectives. The images in the TCIA collection were acquired as per the standard protocol defined by the American College of Radiology. Patients in the age group of 50-80 years were involved in various clinical trials (multicenter). The dataset collection has more than 10 billion of DICOM images of various anatomies. In this study, the number of samples considered for empirical testing was 300 (n) acquired from both supine and prone positions. The datasets were classified based on the parameters of interest. The classified dataset makes the dataset selection easier during empirical testing. The images were validated for the data completeness as per the DICOM standard of the 2020b version. A case study of CT Colonography dataset is discussed.

Conclusion:

With this systematic approach of data collection and classification, analysis will be become more easier during empirical testing.

A quantitative validation of segmented colon in virtual colonoscopy using image moments

Background

Evaluation of segmented colon is one of the challenges in Computed Tomography Colonography (CTC). The objective of the study was to measure the segmented colon accurately using image processing techniques.

Methods

This was a retrospective study, and the Institutional Ethical clearance was obtained for the secondary dataset. The technique was tested on 85 CTC dataset. The CTC dataset of 100–120 kVp, 100 mA, and ST (Slice Thickness) of 1.25 and 2.5 mm were used for empirical testing. The initial results of the work appear in the conference proceedings. Post colon segmentation, three distance measurement techniques, and one volumetric overlap computation were applied in Euclidian space in which the distances were measured on MPR views of the segmented and unsegmented colons and the volumetric overlap calculation between these two volumes.

Results

The key finding was that the measurements on both the segmented and the unsegmented volumes remain same without much difference noticed. This was statistically proved. The results were validated quantitatively on 2D MPR images. An accuracy of 95.265±0.4551% was achieved through volumetric overlap computation. Through pairedt−test, at α=5%, statistical values were p=0.6769, and t=0.4169 which infer that there was no much significant difference.

Conclusion

The combination of different validation techniques was applied to check the robustness of colon segmentation method, and good results were achieved with this approach. Through quantitative validation, the results were accepted at α=5%.

Feasibility of computed tomography colonography as a diagnostic procedure in colon cancer screening in India

Computed Tomography Colonography (CTC) is a medical imaging technology used in identifying polyps and colon cancer masses in the large intestine. The technique has evolved a great deal since its invention and has become a routine diagnostic procedure in Western countries due to its non invasiveness and ease of use. The objective of our study was to explore the possibility of CTC application in Indian hospitals. This paper gives an overview of the procedure and its commercial viability. The explanation begins with the domain aspects from gastroenterologist perspective, the new way of thinking in polyp classification, the technical components of CTC procedure, and how engineering solutions have helped clinicians in solving the complexities involved in colon diagnosis. The colon cancer statistics in India and the results of single institution study we carried out with retrospective data is explained. By considering the increasing number of patients developing colon malignancies, the practicality of CTC in Indian hospitals is discussed. This paper does not reveal any technical aspects (algorithms) of engineering solutions implemented in CTC.

Clinical use of CT colonography for colorectal cancer screening in military training facilities and potential impact on HEDIS measures

PURPOSE

The National Committee for Quality Assurance developed the Healthcare Effectiveness Data and Information Set(®) (HEDIS(®)) to provide quality measures for the evaluation of standards of medical care across health plans. Screening for colorectal cancer (CRC) has been shown to increase the detection of early-stage disease and reduce mortality. Current HEDIS measures for CRC screening include fecal occult blood testing, flexible sigmoidoscopy, and colonoscopy. The aim of this analysis was to quantify the use of CT colonography (CTC) for CRC screening and demonstrate the potential impact of including CTC as a HEDIS-acceptable screening modality.

METHODS

Demographic and health care utilization data from the Military Health System Population Health Portal for January 1, 2005, through December 31, 2010, for individuals aged 50 to 75, were analyzed to determine the degree of overall utilization of CTC. Screening compliance for CRC per HEDIS was also estimated, and the incremental impact of adding HEDIS-eligible patients who had undergone CTC as their only CRC screening test was then evaluated for two similarly sized, regional Navy medical centers.

RESULTS

Across all sites (10 Army, 4 Navy, 3 Air Force), 17,187 CTC studies were performed, with increasing utilization during the 6-year study period. At the two Navy medical centers, screening compliance ranged from 33.8% to 67.9% without CTC and from 33.8% to 84.0% with CTC.

CONCLUSIONS

CTC is actively being used for CRC screening across military treatment facilities. The inclusion of CTC as a HEDIS-compliant CRC screening test has the potential to significantly increase health care system compliance for National Committee for Quality Assurance CRC screening measures.

Evolving role of computed tomographic colonography in colon cancer screening and diagnosis

Computed tomographic colonography (CTC) is a relatively new imaging modality for the examination of patients for colorectal polyps and cancer. It has been validated in its accuracy for the detection of colon cancer and larger polyps (more than likely premalignant). CTC, however, is not widely accepted as a primary screening modality in the United States at present by many third-party payers, including Medicare, and its exact role in screening is evolving. Moreover, there has been opposition to incorporating CTC as an accepted screening instrument, especially by gastroenterologists. Heretofore, optical colonoscopy has been the mainstay in this screening. We discuss these issues and the continuing controversies concerning CTC.

The second ESGAR consensus statement on CT colonography

Objective

To update quality standards for CT colonography based on consensus among opinion leaders within the European Society of Gastrointestinal and Abdominal Radiology (ESGAR).

Material and methods

A multinational European panel of nine members of the ESGAR CT colonography Working Group (representing six EU countries) used a modified Delphi process to rate their level of agreement on a variety of statements pertaining to the acquisition, interpretation and implementation of CT colonography. Four Delphi rounds were conducted, each at 2 months interval.

Results

The panel elaborated 86 statements.

In the final round the panelists achieved complete consensus in 71 of 86 statements (82 %). Categories including the highest proportion of statements with excellent Cronbach's internal reliability were colon distension, scan parameters, use of intravenous contrast agents, general guidelines on patient preparation, role of CAD and lesion measurement.

Lower internal reliability was achieved for the use of a rectal tube, spasmolytics, decubitus positioning and number of CT data acquisitions, faecal tagging, 2D vs. 3D reading, and reporting.

Conclusion

The recommendations of the consensus should be useful for both the radiologist who is starting a CTC service and for those who have already implemented the technique but whose practice may need updating.

Key Points

• Computed tomographic colonography is the optimal radiological method of assessing the colon

• This article reviews ESGAR quality standards for CT colonography

• This article is aimed to provide CT-colonography guidelines for practising radiologists

• The recommendations should help radiologists who are starting/updating their CTC services

CT colonography of a Medicare-aged population: outcomes observed in an analysis of more than 1400 patients

OBJECTIVE

We evaluated outcomes of patients 65 years old and older who underwent CT colonography (CTC) between 2004 and 2009.

CONCLUSION

The frequency of referral to colonoscopy based on a polyp size threshold of 6 mm was 14.5%. Colorectal neoplasia was found in 9.3% of patients, with advanced neoplasia in 3.3%. Potentially important extracolonic findings were observed in 2.9% of patients. The low rates of referral to colonoscopy, prevalence of advanced neoplasia, and prevalence of extracolonic findings make CTC a viable option for Medicare-aged patients.