Rate constant of gadolinium (Gd)-DTPA transfer into chronic subdural hematomas

Gadolinium (Gd) DTPA concentrations in subdural fluid and arterial blood were measured following intravenous Gd-DTPA injection by ion coupled plasma emission spectrometry in 31 chronic subdural hematomas and 12 with subdural effusions. Dynamic biological modeling analysis was used to calculate the unidirectional transfer rate constant (K) for Gd-DTPA influx into the subdural fluid. The Gd concentrations in subdural hematomas and subdural effusions were 36.3 +/- 3.7 nmol ml(-1) and 80.0 +/- 14.0 nmol ml(-1), respectively. The transfer rate constants (K) for subdural hematomas and subdural effusions were 12.4 +/- 1.5 (x10(-4)) min(-1) and 19.7 +/- 2.2(x10(-4)) min(-1), respectively. The Gd concentration and transfer rate constant for subdural effusions were significantly (p<0.05) higher than for subdural hematoma. The Gd transfer rate constant was significantly correlated with the interval from head injury to operation. The present study shows that the immature outer membrane has a high transfer rate constant, allowing extravasation of plasma components into the subdural space and increasing the volume of the subdural effusion; the rate constant decreases with aging of the subdural hematoma.