Role of Amide Proton Transfer Imaging in Maximizing Tumor Resection in Malignant Glioma: a Possibility to Take the Place of C-methionine Positron Emission Tomography

Background: Amide proton transfer (APT) imaging has been proposed as a technique to assess tumor metabolism. However, the relationship between APT imaging and other quantitative modalities including positron emission tomography (PET) has not been investigated in detail. This study aimed to evaluate the clinical usefulness of APT imaging in determining the metabolic status of malignant glioma and to compare findings with those from C-methionine (Met)-PET.

Methods: This research analyzed APT imaging data from 20 consecutive patients with malignant glioma treated between January 2022 and July 2023. Patients underwent tumor resection and correlations between tumor activity and intensity of APT signal were investigated. We also compared C-Met-PET and APT imaging for the same regions of the perifocal tumor invasion area.

Results: Clear, diagnostic APT images were obtained from all 20 cases. Mean APT intensity (APT) was significantly higher in the glioblastoma (GBM), IDH wild type group (27.2 ± 12.8%) than in other gliomas (6.0 ± 4.7%; p < 0.001). The cut-off APT to optimally distinguish between GBM and other malignant gliomas was 12.8%, offering 100% sensitivity and 83.3% specificity. These values for APT broadly matched the tumor-to-contralateral normal brain tissue ratio from C-Met-PET analysis (r = 0.66). The APT signal was also observed in the gadolinium non-contrast region on T1-weighted imaging, appearing to reflect the surrounding tumor-infiltrated area.

Conclusions: APT imaging can be used to evaluate the area of tumor invasion, similar to C-Met-PET. APT imaging revealed low invasiveness in patients and was useful in preoperative planning for tumor resection, facilitating maximum tumor resection including the tumor invasive area.