Using R2* values to evaluate brain tumours on magnetic resonance imaging: preliminary results.

Objective: To determine the usefulness of the R2* value in assessing the histopathological grade of glioma at magnetic resonance imaging and differentiating various brain tumours.

Methods: Sixty-four patients with brain tumours underwent R2* mapping and diffusion-weighted imaging examinations. ANOVA was performed to analyse R2* values among four groups of glioma and among high-grade gliomas (grades III and IV), low-grade gliomas (grades I and II), meningiomas, and brain metastasis. Spearman's correlation coefficients were used to determine the relationships between the R2* values or apparent diffusion coefficient (ADC) and the histopathological grade of gliomas. R2* values of low- and high-grade gliomas were analysed with the receiver-operator characteristic curve.

Results: R2* values were significantly different among high-grade gliomas, low-grade gliomas, meningiomas, and brain metastasis, but not between grade I and grade II or between grade III and grade IV. The R2* value (18.73) of high-grade gliomas provided a very high sensitivity and specificity for differentiating low-grade gliomas. A strong correlation existed between the R2* value and the pathological grade of gliomas.

Conclusions: R2* mapping is a useful sequence for determining grade of gliomas and in distinguishing benign from malignant tumours. R2* values are better than ADC for characterising gliomas.

Key Points: • Magnetic resonance imaging parameters are increasingly used to assess cerebral lesions. • R2* values are better than diffusion weighting for characterising gliomas. • R2* values can help distinguish among different grades of glioma. • Significant difference existed in R2* values between high- and low-grade gliomas.