Use of amide proton transfer (APT) imaging in the differentiation of pediatric low-grade brain tumors from tumor-like brain lesions.

Background And Purpose: Low grade tumors (LGT) are the most frequent central nervous system lesions observed in children. Despite the high-throughput research, differentiating LGT from tumor- like lesions (TLL) and providing an accurate differential diagnosis based on conventional MRI remains a challenge. For this reason, advanced MR sequences are routinely investigated and applied in clinical practice. The aim of this study is to explore the potential of the amide proton transfer (APTw) sequence as a tool for discriminating LGT from TLL.

Materials And Methods: In this single-center retrospective study, we recruited 35 patients (20 with a histologically confirmed LGT, and 15 with a TLL) with both conventional and APT MRI images obtained on a 3T clinical scanner at onset or prior to treatment/surgery. Two volumes of interest (VOI), namely the whole lesion and the normal appearing white matter (NAWM), were defined using the semi-automatic segmentation tool from Philips Intellispace portal for Windows (v. 8). The mean APTw (mAPTw) and difference between the mAPTw lesion and the NAWM (dAPTw) were measured and compared between the two groups.

Results: Lower values were found in the TLL group compared to the LGT group for both the mAPTw (1.51 ± 0.64% vs. 2.87 ± 0.96%) and dAPTw (0.24 ± 0.72% vs. 1.53 ± 1.08%) (p-value < 0.001). Based on ROC curve analysis, optimal cut-offs value for mAPTw and dATPw were 1.79 and 0.53, respectively.

Conclusion: APT imaging may prove useful to discriminate between LGT and TLL in pediatric patients.