Dual-Energy Based Spectral Electronic Cleansing in Non-Cathartic Computed Tomography Colonography: An Emerging Novel Technique

A lthough dual-energy CT (DECT) was first conceived in 1976, it has not been used widely for clinical indications (1-11). Recently, the simultaneous acquisition of dual-energy data has been introduced using multidetector CT (MDCT) with two X-ray tubes and rapid peak kilovoltage (kVp) switching (gemstone spectral imaging, GSI) (12-16). Two major advantages of DECT are material decomposition by the almost simultaneous acquisition of two image series with different kVp (80 and 140 kVp) and the elimination of misregistration artifacts. In general, noncontrast (unenhanced) images can be avoided by using the dual-energy mode for body and neurological applications; iodine can be removed from the image, and a virtual non-contrast (water) image can be acquired. The major advantage of 80-kVp compared to 140-kVp images is a higher image contrast (Fig. 1). Hounsfield unit measurements on DECT are not absolute and can change depending on the kVp used for the acquisition (at different keV). Typically, a combination of 80/140 kVp is used for DECT, but for some applications, 100/140 kVp is preferred. In this study, we summarized the clinical applications of DECT in the brain, chest and abdomen and in the cardiovascular and musculoskeletal systems (Table 1). Technique and principlesThe basic principle of dual-energy is the acquisition of 2 datasets from the same anatomic location with different kVp (usually 80 and 140 kVp) (1,2,17,18). In the early days of CT, consecutive single-slice acquisitions with different kVp were performed as a dual-energy technique, but this method suffered from breathing and partial volume artifacts (1, 2). At present, an entire body can be scanned within seconds using the DECT technique, and thus, misregistration artifacts due to breathing are eliminated.Currently, three systems are capable of the nearly simultaneous acquisition of dual-energy data during a single breath hold (12, 14, 15): 64-slice dual-source CT (Definition, Siemens Medical Systems; Erlangen, Germany), 128-slice dual-source CT (Definition Flash, Siemens Medical Systems) and high-definition 64-MDCT (Discovery 750 HD, GE Healthcare; Milwaukee, Wisconsin, USA). In the two systems available from Siemens, the two tubes (tubes A and B) use different kVp (80 and 140 kVp), and in 64-MDCT, the kVp switches from 80 to 140 kVp in less than 0.5 ms. In dual systems, there is concern regarding the susceptibility of the system to cardiac motion due to the time difference (75 or 83 ms) between the tube A and tube B acquisitions of the dual-energy data, but the dual-source CT and 64-MDCT have not been compared to evaluate this issue. The technical specifications of the DECT systems are summarized in Table 2.The images presented in this article were acquired using a 64-slice dual source CT (Definition, Siemens Medical Systems) and a 64-MDCT (Discovery 750HD, GE Healthcare). The DECT data acquired by both systems can be evaluated with a dedicated workstation using dual-energy software that ABSTRACT Although dual-energy CT (DECT) was first conceived in ...

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“…11). DECT may also be used for spectral electronic cleansing in reduced catharsis CT colonoscopy (101).…”

Section: Dect Colonoscopymentioning

confidence: 99%

Dual-energy CT revisited by multidetector ct: review of principles and clinical applications

Karçaaltıncaba

Aktaş²

2010

Diagn Interv Radiol

154

127

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“…Spectral cleansing is performed on dual-energy CT-derived images to enable the recognition of fecal debris on the bases of both density and materialspecific energy absorption patterns. Spectral cleansing techniques have been reported to provide higher-quality nonconventional CTC images, with fewer artifacts, as compared to standard EC techniques [53]. Clinical performance requires further study.…”

Section: Standard and Spectral Electronic Cleansingmentioning

confidence: 98%

Decreased-Purgation CT Colonography: State of the Art

Mahgerefteh

Blachar

Fraifeld

2011

Curr Colorectal Cancer Rep

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In the setting of CT colonography (CTC), decreasing bowel preparation measures may help to optimize colorectal cancer screening compliance without compromising accuracy. Decreased-purgation or wholly noncathartic CTC, known as nonconventional CTC, may be accomplished in conjunction with fecal tagging. Image post-processing technologies such as electronic cleansing and computer-aided detection may boost accuracy and decrease the need for bowel preparation even further. We review pre-study preparation and image post-processing techniques that have been described in nonconventionalpreparation CTC studies over the past 10 years. We explore in detail specific aspects of nonconventional cathartic and fecal tagging regimens, including substance, dose, and time frame of ingestion.

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“…41) was discussed briefly above. A second approach used dual-energy CT, 42 an unusual type of CTC data in clinical practice. The third is our previous approach to remove heterogeneous stool 43 that suffered from heavy parameterization and was based on minimum variance and curved level sets.…”

Section: Discussionmentioning

confidence: 99%

“…42 and was proven to benefit the detection of colonic polyps submerged in contrast agent. 11 The scatter component, I s , of image I is estimated via a convolution with a symmetric scatter function SF I s ¼ I SF;…”

Section: Iig Colonic Polyp Cadmentioning

confidence: 99%

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Automated image‐based colon cleansing for laxative‐free CT colonography computer‐aided polyp detection

et al. 2011

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Purpose: To evaluate the performance of a computer-aided detection (CAD) system for detecting colonic polyps at noncathartic computed tomography colonography (CTC) in conjunction with an automated image-based colon cleansing algorithm. Methods: An automated colon cleansing algorithm was designed to detect and subtract taggedstool, accounting for heterogeneity and poor tagging, to be used in conjunction with a colon CAD system. The method is locally adaptive and combines intensity, shape, and texture analysis with probabilistic optimization. CTC data from cathartic-free bowel preparation were acquired for testing and training the parameters. Patients underwent various colonic preparations with barium or Gastroview in divided doses over 48 h before scanning. No laxatives were administered and no dietary modifications were required. Cases were selected from a polyp-enriched cohort and included scans in which at least 90% of the solid stool was visually estimated to be tagged and each colonic segment was distended in either the prone or supine view. The CAD system was run comparatively with and without the stool subtraction algorithm. Results: The dataset comprised 38 CTC scans from prone and/or supine scans of 19 patients containing 44 polyps larger than 10 mm (22 unique polyps, if matched between prone and supine scans). The results are robust on fine details around folds, thin-stool linings on the colonic wall, near polyps and in large fluid/stool pools. The sensitivity of the CAD system is 70.5% per polyp at a rate of 5.75 false positives/scan without using the stool subtraction module. This detection improved significantly (p ¼ 0.009) after automated colon cleansing on cathartic-free data to 86.4% true positive rate at 5.75 false positives/scan. Conclusions: An automated image-based colon cleansing algorithm designed to overcome the challenges of the noncathartic colon significantly improves the sensitivity of colon CAD by approximately 15%.

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Dual-Energy Based Spectral Electronic Cleansing in Non-Cathartic Computed Tomography Colonography: An Emerging Novel Technique

Cited by 22 publications

References 21 publications

Dual-energy CT revisited by multidetector ct: review of principles and clinical applications

Dual-energy CT revisited by multidetector ct: review of principles and clinical applications

Decreased-Purgation CT Colonography: State of the Art

Automated image‐based colon cleansing for laxative‐free CT colonography computer‐aided polyp detection

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