sMRI

Structural magnetic resonance imaging (sMRI) refers to MRI methods optimized to image brain anatomy with high spatial resolution. sMRI provides detailed images of brain anatomy, including gray matter, white matter, and cerebrospinal fluid, enabling measurement of morphometric properties such as regional volumes and cortical thickness. It is non-invasive and uses strong magnetic fields and radiofrequency pulses, with no ionizing radiation.

Common acquisition strategies include 3D T1-weighted sequences such as MP-RAGE or SPGR, typically yielding isotropic voxel sizes around 0.8–1.0 mm. T2-weighted and FLAIR sequences are also used to highlight fluid and pathology. At higher field strengths (3T, 7T) higher resolution is possible, and 3D acquisitions allow whole-brain coverage in a single scan.

Applications include clinical evaluation of neuroanatomical abnormalities, neurodegenerative diseases (e.g., Alzheimer's disease), pediatric and developmental studies, brain tumor assessment and surgical planning, and research into brain aging and conditions such as traumatic brain injury. sMRI data also serve as anatomical references for functional MRI and diffusion MRI analyses.

Common analysis steps involve preprocessing to remove non-brain tissue, bias field correction, tissue segmentation into gray matter, white matter, and CSF, and spatial normalization to a standard atlas. Tools such as FreeSurfer, FSL, and SPM perform cortical reconstruction, volumetric analysis, and voxel-based morphometry. Outputs include regional brain volumes, cortical thickness estimates, and 3D reconstructions.

Limitations and safety considerations include susceptibility to motion, scanner artifacts, and variability across scanners and sequences. Contraindications include non-removable metallic implants and severe claustrophobia. sMRI is time-limited, relatively costly, and requires screening for safety and compatibility with MRI hardware.