Amide Proton Transfer in the Differential Diagnosis of Diffuse Astrocytomas and Oligodendrogliomas

Background . Astrocytomas and oligodendrogliomas together account for about half of all cases of adult-type diffuse gliomas. These tumors differ in their sensitivity to radiation therapy and pharmaceutical treatment. Despite the presence of specific radiological patterns, differential diagnosis of these tumors by magnetic resonance imaging (MRI) remains quite challenging, and they are often indistinguishable on standard MR images. Objective . To assess the potential of magnetic resonance imaging weighted by amide proton transfer (APT-weighted imaging) in the differential diagnosis of diffuse astrocytomas and oligodendrogliomas. Materials and Methods . MRI scans were performed on 26 patients aged 22 to 71 years with histologically confirmed diffuse astrocytomas and oligodendrogliomas Grade 2 and Grade 3. The examinations were conducted on a Philips Elition X 3T scanner. The MRI protocol included standard sequences and images weighted by amide proton transfer (APT-weighted imaging). Mean, minimum, and maximum values of APT-signal were obtained in the central and peripheral tumor regions (both absolute and normalized to white matter), as well as in normal white matter. Results . No differences were found in the absolute numerical values of the APT-weighted signal. Astrocytomas Grade 2 and Grade 3 had higher normalized maximum RCAG values in the peripheral part of the tumor with an index of attenuation of minimal APT signal values of 3.42 [2.82; 4.15] compared to oligodendrogliomas — 2.49 [2.05; 2.65] (p = 0.009, Mann — Whitney test). At a cutoff value of 2.99 for normalized maximum values in the peripheral area, the sensitivity for detecting astrocytoma Grade 2–3 was 76.9 %, specificity was 84.6 %, and area under the curve was 0.799. Conclusion . The use of images weighted by amide proton transfer improves the effectiveness of MRI in the differential diagnosis between astrocytomas and oligodendrogliomas Grade 2–3.