In MRI physics, the STIR (Short Tau Inversion Recovery) sequence is used to suppress which tissue?
- A Water (fluid)
- B Fat ✓
- C Muscle
- D Cortical bone
Correct answer: B. Fat
Explanation
STIR sequences suppress fat by applying an inversion pulse and then timing the readout to the null point of fat's longitudinal magnetisation recovery (fat T1 ~260 ms at 1.5T; TI = 0.693 × T1fat ≈ 170–180 ms). Any tissue with T1 similar to fat will also be suppressed. STIR is field-strength independent and suppresses all fat signal, making it robust for detecting marrow oedema and soft tissue pathology. FLAIR suppresses water/CSF, not fat. Cortical bone has no mobile protons and appears dark intrinsically.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.