Dual-energy computed tomography imaging to determine atherosclerotic plaque composition: a prospective study with tissue validation

Daniel R Obaid, Patrick A Calvert, Deepa Gopalan, Richard A Parker, Nick E J West, Martin Goddard, James H F Rudd, Martin R Bennett

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: Identifying vulnerable coronary plaque with coronary CT angiography is limited by overlap between attenuation of necrotic core and fibrous plaque. Using x-rays with differing energies alters attenuation values of these components, depending on their material composition.

OBJECTIVES: We sought to determine whether dual-energy CT (DECT) improves plaque component discrimination compared with single-energy CT (SECT).

METHODS: Twenty patients underwent DECT and virtual histology intravascular ultrasound (VH-IVUS). Attenuation changes at 100 and 140 kV for each plaque component were defined, using 1088 plaque areas co-registered with VH-IVUS. Hounsfield unit thresholds that best detected necrotic core were derived for SECT (conventional attenuation values) and for DECT (using dual-energy indices, defined as difference in Hounsfield unit values at the 2 voltages/their sum). Sensitivity of SECT and DECT to detect plaque components was determined in 77 segments from 7 postmortem coronary arteries. Finally, we examined 60 plaques in vivo to determine feasibility and sensitivity of clinical DECT to detect VH-IVUS-defined necrotic core.

RESULTS: In contrast to conventional SECT, mean dual-energy indices of necrotic core and fibrous tissue were significantly different with minimal overlap of ranges (necrotic core, 0.007 [95% CI, -0.001 to 0.016]; fibrous tissue, 0.028 [95% CI, 0.016-0.050]; P < .0001). DECT increased diagnostic accuracy to detect necrotic core in postmortem arteries (sensitivity, 64%; specificity, 98%) compared with SECT (sensitivity, 50%; specificity, 94%). DECT sensitivity to detect necrotic core was lower when analyzed in vivo, although still better than SECT (45% vs 39%).

CONCLUSIONS: DECT improves the differentiation of necrotic core and fibrous plaque in ex vivo postmortem arteries. However, much of this improvement is lost when translated to in vivo imaging because of a reduction in image quality.

Original languageEnglish
Pages (from-to)230-7
Number of pages8
JournalJournal of Cardiovascular Computed Tomography
Volume8
Issue number3
DOIs
Publication statusPublished - 2 May 2014

Keywords

  • Humans
  • Plaque, Atherosclerotic
  • Prospective Studies
  • Radiography, Dual-Energy Scanned Projection
  • Sensitivity and Specificity
  • Tomography, X-Ray Computed

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