Diffusion-Weighted Echo-Planar MRI of the Brain with Calculated ADCs: A Useful Tool in the Differential Diagnosis of Tumor Necrosis from Abscess?

BACKGROUND AND PURPOSE: It was the aim of this study to evaluate whether brain abscesses could be distinguished reliably from necrotic brain tumors using diffusion-weighted imaging (DWI) with calculated apparent diffusion coefficients (ADCs). METHODS: The authors studied 27 lesions in 26 patients (21 tumors and metastases, 5 pyogenic brain abscesses, and 1 cerebral toxoplasmosis). DWI was obtained with a single-shot echo-planar imaging spin-echo sequence. ADCs were calculated for all images. RESULTS: ADCs (x 10(-3) mm2/s) measured in the necrotic parts of the tumors ranged from 2.94 (glioblastoma) to 1.51 (astrocytoma III). In the inflammatory lesions, ADCs ranged between 0.91 and 3.07 (cerebral toxoplasmosis and pyogenic abscess). The contrast-enhanced parts of the lesions showed ADC values from 0.77 (pyogenic abscess) up to 1.68 (glioblastoma). CONCLUSIONS: DWI with calculated ADC values does not allow the reliable differentiation of enhanced central necrotic intracranial lesions.