RT Journal Article SR Electronic T1 Band-selective IR PRESS for brain tumor spectroscopy allows robust detection of lactate JF bioRxiv FD Cold Spring Harbor Laboratory SP 2024.09.30.615849 DO 10.1101/2024.09.30.615849 A1 Kishimoto, Shun A1 Kim, Olga A1 Munasinghe, Jeeva A1 Yasunori, Otowa A1 Kota, Yamashita A1 Yamamoto, Kazutoshi A1 Linehan, W. Marston A1 Wu, Jing A1 Krishna, Murali C A1 Brender, Jeffrey R YR 2024 UL http://biorxiv.org/content/early/2024/09/30/2024.09.30.615849.abstract AB Lactate plays a critical role in the tumor microenvironment, driving tumor progression, metastasis, and immune evasion. Despite its importance, in vivo quantification of lactate using magnetic resonance spectroscopy (MRS) has faced challenges, primarily due to the overlapping lipid signal at 1.3 ppm. Current clinical practice employs a long echo time to exploit differences in T2 relaxation between lactate and lipids; however, this approach significantly suppresses signals from other metabolites. Lipid has a notably different T1 relaxation time than lactate and other metabolites, which may be exploited by an inversion recovery sequence to better distinguish them. However, this method has not found wide use because of the loss of signal in other metabolites. Here we introduce a selective inversion pulse with a short echo time MRS method (SPIR-PRESS), which mitigates this issue. In phantom experiments, SPIR-PRESS successfully suppressed lipid signals that could be misinterpreted as lactate in short TE PRESS spectra, while maintaining sensitivity to the full metabolite profile. SPIR-PRESS demonstrated superior performance in quantifying lactate compared to long echo time PRESS, with ∼ 60 % increase in sensitivity for lactate detection compared to conventional PRESS with a 288 ms TE. In a mouse glioma model, SPIR-PRESS clearly detected lactate and other key tumor metabolites (choline, creatine, NAA) in the tumor, which were not detectable in conventional long TE PRESS. These findings highlight SPIR-PRESS as a promising technique for improved lactate quantification and comprehensive metabolite profiling in tumor environments.Competing Interest StatementThe authors have declared no competing interest.