STIR (Short Tau Inversion Recovery) sequences are fat-suppressed T2-weighted sequences that are highly sensitive to fluid and edema within the bone marrow. They nullify the signal from fat, making areas of increased water content (due to inflammation, infection, or tumor) appear hyperintense, thus being superior to conventional T2-weighted images for detecting early bone marrow changes in conditions like discitis-osteomyelitis. T1-weighted images show anatomical detail but are less sensitive to edema. T2-weighted images show edema but are less specific due to high fat signal. DWI is useful for restricted diffusion but not the primary sequence for marrow edema.
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