Delayed magnetic resonance imaging with Gd-DTPA differentiates subdural hygroma and subdural effusion

BACKGROUND Posttraumatic subdural fluid collection is not a single clinical entity but can be divided into subdural hygroma and subdural effusion. Appropriate treatment requires preoperative differentiation. Delayed magnetic resonance (MR) imaging with intravenous administration of gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) was used to differentiate subdural hygroma and subdural effusion. METHODS Timed arterial blood specimens were taken after intravenous Gd administration in patients with posttraumatic subdural fluid collections (five subdural hygromas and 13 subdural effusions). Delayed MR imaging was performed 1 hour alter administration of Gd-DTPA. Gd-DTPA concentrations in the subdural fluid and blood specimens were measured by ion coupled plasma emission spectrometry. Dynamic biologic modeling was used to calculate the transfer rate constant for Gd-DTPA influx into these subdural fluid collections. RESULTS The Gd concentrations in subdural hygromas and subdural effusions were 16 +/- 6 and 79 +/- 12 nmol/mL, respectively. The transfer rate constants for subdural hygromas and subdural effusions were 4.8 +/- 2.1 and 20.6 +/- 2.1 (x10(-4))min(-1), respectively. These values were significantly higher in subdural effusions than in subdural hygromas (p < 0.01). Delayed MR imaging with Gd showed significantly higher mean enhancement of 77.1 +/- 14.2% for subdural effusions compared to 4.6 +/- 3.1% for subdural hygromas (p < 0.01). CONCLUSIONS Delayed MR imaging with Gd can differentiate subdural hygroma and subdural effusion. (C) 2000 by Elsevier Science Inc.