A study of CT monochromatic imaging for quantitative detecting hemoglobin levels

The purpose of this study was to investigate the value of spectral CT monoenergetic imaging for detecting hemoglobin levels.

Sixty-five hospitalized patients received chest non-contrast CT scan in gemstone spectral imaging (GSI) mode on a GE Discovery CT750 HD. This study was approved by the hospital ethics committee and informed consent was signed by every patient. Raw data were reconstructed at 1.25 mm and then transferred to a AW4.4 workstation. The CT value of the ascending aorta at 40 keV∼140 keV was measured under GSI viewer of AW4.4. Hemoglobin contents were measured biochemically within 24 hrs after CT scan. The SPSS 16.0 software package was used to analyze the correlation between the obtained CT value and hemoglobin level.

At 40 keV ∼ 100 keV, the CT value decreased followed by the increase of keV and gradually stabilized at 100 keV ∼ 140 keV with an amplitude variation of 10 HU. The CT values measured at 40 keV ∼ 140 keV were well correlated with hemoglobin levels. The optimal correlation was observed at the monoenergetic level of 70 keV (r=0.633, p=0.000). The relationship between CT value and hemoglobin content could be expressed as CT value=13.015+0.245 × hemoglobin content. At 40 keV ∼ 140 keV, there is strong linear correlation between the CT value of the ascending aorta and hemoglobin content. The optimal linear relationship was observed at 70 keV.

Spectral CT monoenergetic imaging can be applied for quantitative determination of hemoglobin content within a specified area of the circulatory system.