Delayed magnetic resonance imaging with GdD-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 after 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.