PURPOSE

We aimed to quantify the cerebral OEF using MR in patients with MELAS in different phases.

METHOD AND MATERIALS

From December 2009 to December 2011, 35 cases in 32 patients with MELAS were examined by MR, Sixteen cases in the acute and subacute phase(group 1),and 19 cases in the interictal phase(group 2) were included. Twenty-four healthy volunteers (group 3) were recruited for control subjects.
 A newly-designed sequence, named gradient-echo sampling of spin echo (GESSE), was applied to obtain the cerebral OEF data on the axial section just above the lateral cerebral ventricle. Six regions of interest (ROI) were placed on the section. We obtained six OEF values and then calculated the mean value, which was the cerebral OEF of this section. In the 13 patients with unilateral cerebral involvement in acute and subacute phase, additional ROIs were placed on the lesions and the uninvolved contralateral counterparts.
 

RESULTS

Significant difference in cerebral OEF was found among different groups by using variance of analysis. OEF was reduced in the patients with MELAS compared with normal people, and the OEF values in the acute and subacute lesions were lower than those in the interictal phase.( acute and subacute phase: 0.266±0.026 ; the interictal phase: 0.295±0.009; volunteers: 0.316±0.025 , F=26, p<0.01). Eleven of 13 selected ROIs have lower values than the uninvolved contralateral hemispheres (rank sum test, p<0.05).

CONCLUSION

The quantification of cerebral OEF, might be applied to evaluate the pathogenesis and prognosis of MELAS.