Objective      To determine the value of amide proton transfer (APT) imaging derived from chemical exchange saturation transfer (CEST) in the differential diagnosis between high grade glioma and brain metastasis.  Methods      A retrospective analysis of 25 patients with pathologically confirmed brain tumors in our hospital from May 2015 to May 2016 were carried out. Among the patients

15 cases were high grade gliomas and 10 were brain metastasis

which part of the metastases were evidenced by clinical history. Conventional MRI and APT imaging were performed using a 3.0T MRI scanner. The APT signal intensity (SI) was measured in the tumor core regions and tumor surrounding tissues (edema region

or the area at 0.5 cm distanced from the tumor core if no obvious edema was found). The APT SI was compared between high grade glioma and brain metastasis.  Results       High SI was detected in the tumor core for both high grade glioma and brain metastasis on APT images with corresponding APT SI values of (2.89±0.76)% and (2.72±0.68)% vespectively. The minor difference was not statistically significant between the 2 groups (P=0.117). In contrast

the APT SI of tumor surrounding tissue was significantly higher in high grade gliomas than in brain metastasis

with significant difference [(1.46±0.52)% vs (0.71±0.39)%

P=0.001].  Conclusion      APT imaging

a novel molecular and cellular MR technique

is useful in differentiating high grade glioma from brain metastasis by measuring the APT SI of tumor surrounding tissue.