biostudies-literatureLaMaster JGerman Academic Exchange ServiceNIH HHSe70130https://www.ebi.ac.uk/biostudies/studies/S-EPMC12439243biostudies-literatureUnknown38(10)Realistic, in vivo-like synthetic data is increasingly needed to develop and validate methods in magnetic resonance spectroscopy. MRS-Sim is a powerful, open-source framework for simulating such data while providing known ground truth values. Its modularity enables modeling the complexities of MRS data for various in vivo scenarios. The underlying physical equations include both commonly used spectral components of linear-combination fitting routines and two novel components. The first is a 3D B0$$ {B}_0 $$ field map simulator that models B0$$ {B}_0 $$ field inhomogeneities, ranging from slight variations to severe distortions. The second is a novel semi-parametric generator that mimics signals from poorly characterized residual water regions and spectral baseline contributions. This frameNMR in biomedicineMRS-Sim: Open-Source Framework for Simulating In Vivo-Like Magnetic Resonance Spectra.PMC1243924357381412R01 CA273028R01 CA262630R21 EB033516R00 AG062230Li YLaMaster JOeltzschner GfalseMRS-Sim: Open-Source Framework for Simulating In Vivo-Like Magnetic Resonance Spectra.Realistic, in vivo-like synthetic data is increasingly needed to develop and validate methods in magnetic resonance spectroscopy. MRS-Sim is a powerful, open-source framework for simulating such data while providing known ground truth values. Its modularity enables modeling the complexities of MRS data for various in vivo scenarios. The underlying physical equations include both commonly used spectral components of linear-combination fitting routines and two novel components. The first is a 3D B0$$ {B}_0 $$ field map simulator that models B0$$ {B}_0 $$ field inhomogeneities, ranging from slight variations to severe distortions. The second is a novel semi-parametric generator that mimics signals from poorly characterized residual water regions and spectral baseline contributions. This frame2025-01-01T00:00:00Z2025 Oct2026-06-01T06:24:57.232Z2026-04-08T09:46:38.581ZS-EPMC124392434095568210.1002/nbm.70130