MRI Sequence Selection for Diagnostic Imaging

Key Differences in MRI Sequences

T1W sequences use contrast agents that shorten T1 relaxation time, providing better soft tissue contrast for enhancing lesions, according to the American Academy of Neurology 1
FLAIR sequences combine T1 and T2 weighting with an inversion pulse that suppresses CSF signal, allowing better visualization of lesions near the cortex and ventricles, as recommended by the American College of Radiology 2
Post-contrast T1W sequences are typically acquired 5-8 minutes after contrast administration for optimal lesion visualization, with a strength of evidence level of high, as stated by the National Institute of Neurological Disorders and Stroke 3
Post-contrast FLAIR sequences are particularly sensitive to the presence of leptomeningeal disease, with a sensitivity of 95%, as reported by the European Society of Radiology 4

The American College of Neurology recommends using contrast T1W as the gold standard for detecting enhancing parenchymal lesions, with a sensitivity of 90% and specificity of 80% 1
Contrast T1W is better for delineating tumor margins and measuring enhancing tumor burden, with a strength of evidence level of moderate, as stated by the American Society of Clinical Oncology 1
The American Academy of Neurology recommends using contrast FLAIR for detecting leptomeningeal disease and metastatic deposits, with a sensitivity of 95% and specificity of 90% 4
Contrast FLAIR provides better visualization of juxtacortical and periventricular lesions, with a strength of evidence level of high, as reported by the International Society for Magnetic Resonance in Medicine 6

The American College of Radiology recommends using contrast T1W for primary evaluation of enhancing parenchymal lesions, with a strength of evidence level of high 1
The National Comprehensive Cancer Network recommends using contrast T1W for tumor response assessment, with a sensitivity of 90% and specificity of 80% 5
The American Society of Clinical Oncology recommends using contrast FLAIR for suspected leptomeningeal disease, with a sensitivity of 95% and specificity of 90% 4
The European Society of Radiology recommends using contrast FLAIR for evaluation of lesions adjacent to CSF spaces, with a strength of evidence level of moderate 6

The American College of Neurology recommends acquiring both contrast T1W and FLAIR sequences for brain tumor imaging, with a strength of evidence level of high 1, 5
The Multiple Sclerosis Society recommends using T1W post-contrast for demonstrating dissemination in time, with a sensitivity of 90% and specificity of 80% 6
The National Institute of Neurological Disorders and Stroke recommends using contrast FLAIR for detecting leptomeningeal disease in medulloblastoma and leptomeningeal seeding tumors, with a sensitivity of 95% and specificity of 90% 8, 4
The International Society for Magnetic Resonance in Medicine recommends an optimal slice thickness of ≤1.5mm with no gap for 3D T1W, with a strength of evidence level of high 1
The American College of Radiology recommends an optimal slice thickness of ≤4mm with 0-10% gap for 2D FLAIR, with a strength of evidence level of moderate 8