ABSTRACT
Objective To explore the application of amide proton transfer (APT) imaging in differentiating glioma from treatment effect and to evaluate the diagnostic efficiency of the quantitative APT-related parameters.Methods A total of 23 patients (15 males, 8 females, age: 13-80 years) with 27 lesions who had underwent APT imaging in Tongji Hospital(Wuhan, China) from October 2014 to June 2015 were enrolled in this prospective study.The scan protocols were MRI normal plain scanning, diffusion WI, contrast-enhancement T1WI and APT imaging.Both the magnetization transfer ratio (MTR) and the relative MTR (rMTR) of lesions were manually measured by drawing ROI in the functional post-processing workstation.The results were compared with those of pathologic examinations and radiographic follow-up (≥3 months).Mann-Whitney u test was used to analyze the data.Results Compared with contralateral white matter, the primary gliomas (n=12) and recurrent gliomas (n=8) manifested hyper-intensity, while the treatment induced injuries (n=7) showed iso-or hypo-intensity.The difference of MTR between tumors and treatment effects was significant (102.78(101.93,103.84) vs 100.17(99.94, 100.63);z=-3.76, P<0.01), so was the difference of rMTR between tumors and treatment effects (3.92%(2.69%,4.67%) vs 0.47%(-0.79%,1.11%);z=-3.43, P<0.01).Both those two quantitative parameters exhibited excellent diagnostic performance with the AUC of 0.986 and 0.943.The sensitivity, specificity and accuracy of MTR were 100%(20/20), 6/7 and 96.3%(26/27) in the threshold of 100.68, while those of rMTR were 95.0%(19/20), 6/7 and 92.6%(25/27) in the threshold of 1.66%.Conclusions Combined with the routine MRI images, APT imaging can provide excellent qualitative and quantitative information in differentiating glioma from treatment effect.Both MTR and rMTR are helpful for the differentiation with high sensitivity and specificity and can be used as non-invasive imaging biomarkers in evaluating treatment effect of glioma.