การตรวจหาภาวะโลหิตจางโดยใช้การวัดค่าความหนาแน่นทางรังสี สำหรับผู้ป่วยที่เข้ารับการตรวจเอกซเรย์คอมพิวเตอร์ทรวงอกในโรงพยาบาลเสนา

Thidaporn Tangyoosuk

Authors

Thidaporn Tangyoosuk Sena hospital, Phra Nakhon Si Ayutthaya Provincial Public Health Office, Office of the Permanent Secretary, Ministry of Public Health.

Keywords:

Hounsfield unit, anemia, computed tomography

Abstract

Objective: To investigate the correlation between hemoglobin (Hb) levels and Hounsfield unit (HU) values in patients undergoing thoracic computed tomography (CT) at Sena Hospital, and to determine the optimal HU cutoff value for detecting anemia.

Methods: This retrospective study included 143 patients who underwent thoracic CT at Sena Hospital, Phra Nakhon Si Ayutthaya Province, between May 2024 and February 2025. HU measurements were obtained at the left ventricular chamber, aortic arch, pulmonary trunk, ascending aorta, and descending aorta. The correlations between HU values and anemic status were analyzed using t test or Mann-Whitney U test, as appropriate, and binary logistic regression. Parameters with statistical significance were subsequently entered into a multivariable logistic regression model, and receiver-operating characteristic (ROC) analysis was performed to determine optimal cutoff values based on sensitivity, specificity, and area under the curve (AUC).

Results: Of the 143 patients, 94 (65.7%) were anemic. The mean HU values at all five measurement sites were significantly lower in anemic patients compared to non-anemic patents (p < .001). Binary logistic regression revealed significant correlations between anemia and HU at the aortic arch (OR 0.722; 95% CI, 0.612–0.852; p < .001) and descending aorta (OR 0.861; 95% CI, 0.757–0.980; p = .023), while HU at the left ventricular chamber, pulmonary trunk and ascending aorta showed no significant associations. Multivariate logistic regression incorporating HU values from both the aortic arch and descending aorta improved the discriminatory performance for anemia detection. The optimal cutoff HU values for detecting anemia were 44.5 HU at the aortic arch (sensitivity 89.4%, specificity 75.5%) and 43.5 HU at the descending aorta (sensitivity 73.4%, specificity 75.5%).

Conclusion: A HU value at the aortic arch below 44.5 HU may serve as a potential noninvasive screening tool for anemia in Thai patients undergoing thoracic CT for any indication.

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