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High-Definition CT Gemstone Spectral Imaging of the Brain

2011; Lippincott Williams & Wilkins; Volume: 35; Issue: 2 Linguagem: Inglês

10.1097/rct.0b013e3182058d5c

1532-3145

Xiao Lin, Fei Miao, Jian Ying Li, Hai Peng Dong, Yun Shen, Ke Min Chen,

Medical Imaging Techniques and Applications

Objective: The purpose of this study was to select the optimal monochromatic level for gemstone spectral imaging (GSI) to minimize both the image noise and beam-hardening artifacts (BHAs) in nonenhanced cranial computed tomography (CT). Materials and Methods: One hundred subjects scanned with GSI mode on Discovery CT750HD were enrolled. Six sets of CT images were obtained from a single GSI acquisition: conventional 140 kilovolt (peak) (kV[p]) polychromatic images and 5 sets of monochromatic images (80, 75, 70, 65, and 60 kiloelectron volts [keV]). The background noise in the corona and the BHA in 4 different anatomic regions (medulla oblongata, cerebellar, pons, and the inferior part of frontal lobes) were measured and compared between the polychromatic and monochromatic images. Beam-hardening artifact is defined as the square root of the squared noise difference between the region of interest and background. Results: The background noise with the monochromatic sets reduced by −36%, −11%, 11%, 10%, and −14%, respectively, compared to the polychromatic image. For BHA, the reductions were 73%, 91%, 92%, and 80%; 53%, 75%, 65%, and 41.%; 27%, 59%, 44%, and 26%; 7%, 46%, 25%, and 20%; and −14%, 33%, 6%, and 19% for the 4 regions of interest. Both the 70 and 65 keV sets had positive background noise reduction (P = 0.285) and BHA reduction with 70 keV were statistically higher (P < 0.05). Conclusion: In the nonenhanced cranial CT with GSI, the optimal monochromatic level was determined at 70 keV to provide both image noise reduction (11%) and BHA reduction compared to the conventional polychromatic images.