Correlation of phase values with CT Hounsfield and R2* values in calcified neurocysticercosis

To correlate phase and R2* derived from susceptibility-weighted magnetic resonance imaging (MRI) with computed tomography-Hounsfield (CT-HU) values in calcified neurocysticercosis and to evaluate phase imaging in the assessment of calcified neurocysticercosis.

Thirty-five patients with 52 calcified lesions underwent both CT and MRI. Phase and R2* were calculated from multi-echo 3D-T2-star-weighted-angiography data. MRI and CT data were coregistered using mutual information. Spearman's correlation was performed between quantitative phase and CT-HU and R2* values. The Mann-Whitney U-test was used to see differences between CT-HU and R2* values from corresponding positive and negative phase regions.

The median values of CT-HU and R2* from regions with positive and negative phase were found to be 142.10 (range: 41.89-491.75) and 68.5/sec (range: 20-110/sec) and 137.30 (range: 30.83-458.88) and 69/sec (range: 0-110/sec), respectively. There was a significant correlation of positive phase values with corresponding CT-HU and R2* values. In addition, there was a significant correlation of R2* and CT-HU with negative phase values.

We conclude that there is a significant correlation between negative and positive phase with CT-HU and R2* values, suggesting that the CT hyperdense lesion may have both calcium and other minerals, which can be differentiated using phase imaging. Conventional MRI should include phase imaging to detect calcified neurocysticercosis.