A Multi-Center Study of Near-Infrared Spectroscopy (NIRS) for Hematoma Detection

The purposes of this study are: To determine the sensitivity and specificity of the Near-Infrared Spectroscopy (NIRS) measurements for identifying intracranial hematomas due to trauma. To determine the reproducibility of the Near-Infrared Spectroscopy (NIRS) measurements with different operators and at different centers

The principle used in identifying intracranial hematomas with Near-infrared spectroscopy (NIRS) is that extravascular blood absorbs Near-infrared light more than intravascular blood since there is a greater (usually 10-fold greater) concentration of hemoglobin in the acute hematoma then in the brain tissue where blood is contained within vessels. Therefore, the absorbance of Near-infrared light is greater (and therefore the reflected light less) on the side of the brain containing a hematoma, than on the uninjured side. The NIRS sensor is placed successively in the left and right frontal, temporal, parietal, and occipital areas of the head and the absorbance of light at selected wavelengths is recorded. The difference in optical density in the different areas is calculated.

1) Sensitivity of the Near-Infrared Spectroscopy (NIRS) Measurements for Identifying Intracranial Hematomas Due to Trauma. 2) Specificity of the Near-Infrared Spectroscopy (NIRS) Measurements for Identifying Intracranial Hematomas Due to Trauma.

We will report Sensitivity and Specificity of NIRS device as compared to CT scanner to detect hematomas of more than 3.5 mL in volume and less than 2.5 cm from the surface of the brain. Sensitivity is the ratio between true positives to all positive measurements. Specificity is the ratio between true negatives to all negative measurements.

Inclusion Criteria: Undergoing a CT scan within 12 hours of their head injury. The criteria for obtaining a CT scan will be based on the standard of care, but generally all patients with a moderate or severe head injury will receive a CT scan on admission to the hospital, and only patients who undergo a CT will be enrolled into the study. The non-contrast CT will be performed according to standard methods. Exclusion Criteria: 12 hours or more since injury. Massive scalp lacerations, avulsions, and hematomas The limitation to injury within 12 hours is necessary because as hematoma blood is metabolized, the absorbance characteristics change.

Professor Medical Director, The Center for Neurosurgical Intensive Care, Ben Taub Hospital, Houston, Texas

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