What is the purpose of the STIR sequence in MRI?

The STIR sequence, or Short Tau Inversion Recovery sequence, is specifically designed for robust fat suppression in MRI (Magnetic Resonance Imaging). This technique utilizes an inversion recovery method with a specific TI (inversion time) that effectively nulls the fat signal, allowing for clearer imaging of adjacent tissues, particularly in cases where fat may obscure pathology.

By suppressing the fat signal, the STIR sequence enhances the visibility of water-containing tissues, making it particularly valuable in evaluating conditions where fat saturation is essential for accurate diagnosis, such as in musculoskeletal imaging and certain oncological assessments. The precise timing of the inversion pulse is crucial, as it determines the effectiveness of the fat suppression.

While it may seem that enhancing contrast, improving imaging speed, or reducing scan time could also be important features in MRI, the primary and most significant function of the STIR sequence is its ability to provide reliable fat suppression, which is critical for optimal tissue differentiation.