MR imaging of high-grade brain tumors using endogenous protein and peptide-based contrast

Abstract

Amide proton transfer (APT) imaging is a novel MRI technique, in which the amide protons of endogenous proteins and peptides are irradiated to accomplish indirect detection using the bulk water signal. In this paper, the APT approach was added to a standard brain MRI protocol at 3T, and twelve patients with high-grade gliomas confirmed by histopathology were scanned. It is shown that all tumors, including one with minor gadolinium enhancement, showed heterogeneous hyperintensity on the APT images. The average APT signal intensities of the viable tumor cores were significantly higher than those of peritumoral edema and normal-appearing white matter (P < 0.001). The average APT signal intensities were significantly lower in the necrotic regions than in the viable tumor cores (P = 0.004). The APT signal intensities of the cystic cavities were similar to those of the viable tumor cores (P > 0.2). The initial results show that APT imaging at the protein and peptide level may enhance non-invasive identification of tissue heterogeneity in high-grade brain tumors.

In vivo chemical exchange saturation transfer imaging allows early detection of a therapeutic response in glioblastoma

“…Although our present study was conducted by using a 7-T animal MRI scanner, the current clinical standard for high-field MRI scanners (3 T) would suffice for quantitative assessment of APT, as demonstrated in our previous study (18) and other studies (17,43). It is known that CEST and APT should be enhanced at higher magnetic fields as a result of improved sensitivity and spectral resolution.…”

Downfield‐NOE‐suppressed amide‐CEST‐MRI at 7 Tesla provides a unique contrast in human glioblastoma

“…There are more and more efforts to bring CEST into the clinical decision process for brain cancer diagnosis (17,21,(50)(51)(52). A CEST contrast with the features presented in this work, is of special interest as reliable identification of infiltrative tumor progression that is not necessarily accompanied by enhancement on T 1 -weighted images is still a challenge faced by neuro-oncologic imaging (53,54).…”

“…For these protein ST effects, several interesting correlations have been shown that might play a role in vivo and especially in pathologies: dependence on intracellular pH (5,(10)(11)(12)(13), protein concentration (8,13), or protein folding (14,15) and aggregation states (16). Already, the use for brain tumor detection (6,(17)(18)(19)(20), grading (21), and possible differentiation of tumor recurrence and radiation necrosis (22) has been shown to be feasible by proteinbased saturation transfer MRI.…”

7 tesla imaging of cerebral radiation necrosis after arteriovenous malformations treatment using amide proton transfer (APT) imaging

“…In another study, involving 12 patients with high grade gliomas, an increased signal in solid tumor tissue and a significantly lower signal in necrotic areas was found (13). Furthermore, Mougin et al recently demonstrated the advantageous influence of 7T on the APT signal in comparison to 3T (14), which is mainly attributed to increased T1 relaxation times and higher chemical shift dispersion.…”