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Improved Conspicuity of Abdominal Lesions with Single-Source Dual-Energy MDCT

Ruth Eliahou MD, Jacob Sosna, MD. Improved Conspicuity of Abdominal Lesions with Single-Source Dual-Energy MDCT. AFIIM 2008. Hadassah Hebrew University Medical Center Jerusalem, Israel. 1972 – First single slice CT. 2005 – Single-Source Dual-Energy MDCT.

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Improved Conspicuity of Abdominal Lesions with Single-Source Dual-Energy MDCT

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  1. Ruth Eliahou MD, Jacob Sosna, MD Improved Conspicuity of Abdominal Lesions with Single-Source Dual-Energy MDCT AFIIM 2008 Hadassah Hebrew University Medical Center Jerusalem, Israel

  2. 1972 – First single slice CT 2005 – Single-Source Dual-Energy MDCT

  3. Spectrum Decomposition Principle: Photons in the x ray beam of the CT scanner have different energies Pre-patient Beam filtration Low-Energy X-ray radiation High-Energy X-ray radiation Intensity KV

  4. X-Rays E1 SCINT1 E2 SCINT2 Dual-Energy CT • 64 detectors • PHILIPS Brilliance CT Prototype • 32 detectors for low energy • 32 detectorsfor high energy

  5. Each scan creates 3 types of images: low energy image combined image high energy image

  6. Every pixel has 2 HU values – for high & low energy -106/-135 -986/1003 +23/+35 +119/147 +197/236 +329/389 +191/215

  7. Dual-Energy CTmain advantages: • Separation • Contrast

  8. A separation line can be calculated each material has a different separation line

  9. 5. Calcium Avg 306 5. Calcium 4. Barium Avg 488 4. Barium 6. Gadolinium Avg 362 6. Gadolinium 3. 20% oil 7. Cis Platinum Avg 26.6 7. Cis Platinum 3. 20% oil Avg: -16 2, Oil 8. Water 8. Water Avg 1.3 2, Oil Avg: -102 1. Iodine 1. Iodine Avg: 319 Materials Separation

  10. Dual-Energy CTmain advantages: • Separation • Contrast

  11. Dual-Energy Imaging CT density of tissues is the result of interactions between x-ray photons and tissues: • Compton scattering • Photoelectric effect At Low Voltage: Photoelectric effect is increased Compton scattering is decreased Contrast is improved higher attenuation readings of iodine are obtained

  12. Purpose • To quantitatively and qualitatively evaluate lesion conspicuity & Contrast to Noise ratio of abdominal lesions with DECT.

  13. Materials and Methods • A prospective study (9 / 2006 – 2 / 2008) • Each patient signed an informed consent • All studies were clinically indicated • Study population: 23 patients • Average age 58 years (range 36-86)

  14. Materials and Methods • CT parameters • 2-3mm slice thickness • 1-1.5 mm increment • 140 kVp • 250-300 mAs • 100 cc of nonionic contrast • 1.5-2 cc/sec • Regions-of-interest (ROI) were drawn on the lesion evaluated and the adjacent organ

  15. Contrast-to-Noise Ratio • CNR was defined as the difference in attenuation between the lesion and the organ, divided by the air SD for both the low-energy and regular CT images (for fixed ROI)

  16. HU lesion – HU organ SD air CNR=

  17. Lesion Contrast Qualitative Assessment • Low energy and regular CT images were visually compared using the same window • Lesion conspicuity was graded on a predetermined scale • No difference = 0 • Significant change = 3

  18. Results • 37 lesions • 27 solid • 10 cystic • Organs • 14 kidney • 12 liver • 5 ovary • 4 lymph nodes • 2 fluid collections

  19. Results • Improved CNR was noted for both lesion types • Solid lesion CNR • 2.11 (SD=0.4) with low energy • 1.76 (SD=0.26) for regular CT (p<0.01) • Cystic lesion CNR • 8.24 (SD=0.64) with low energy • 7.58 (SD=0.46) for regular CT (p<0.03)

  20. Results On visual inspection • Low energy • 2.1 for conspicuity & lesion-to-organ contrast, solid lesions • 2.4 for cystic lesions • Regular CT • 1.8 for conspicuity & lesion-to-organ contrast, solid lesions • 2.05 for cystic lesions

  21. Results Combined Low Energy

  22. Results Combined Low Energy

  23. So, If better lesion conspicuity Why not scan with low kV all the time? Noisy image, Data may be lost!

  24. Conclusions • Improved conspicuity of solid and cystic abdominal and pelvic lesions on low energy images obtained using single-source dual-energy MDCT • May enable earlier detection of small lesions and improved diagnosis of neoplastic processes

  25. Work in Progress Digital Subtraction (electronic cleansing) of tagged stool in computed tomographic colonography based on the Dual energy imaging separation capabilities

  26. Our CTC Study: • Aim:To compare prep- less dual energy CTC with OC for evaluation of colorectal polyps • Hypothesis: Dual Energy prep- less CTC can: • reliably detect polyps ≥ 10 mm • Superior digital cleansing

  27. Study design: • 100 high risk patients • Will be referred by gastroenterologists to research fellow for preparation guidelines • CTC will be performed and analyzed • 3 wks later, OC with video taping will be performed with segmental unblinding as a gold standard

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