Speckled STIR Hyperintensities on MRI

Technical Basis

The American College of Cardiology recommends using STIR sequences to detect increased water content in tissues, which are highly sensitive for detecting increased water content in tissues 1

Speckled STIR hyperintensities in bone and soft tissue typically represent bone marrow edema, inflammatory changes, or stress reactions, according to the American College of Radiology 2, 3, 4
The American College of Radiology states that in sacroiliac joints, these findings indicate active inflammation in axial spondyloarthropathy, though bone marrow edema can be nonspecific and seen in up to 30% of healthy controls 4, 5
Deep bone marrow edema lesions extending at least 1 cm deep to the articular surface are more specific for pathologic inflammation, as reported by the American College of Radiology 4, 5

The American College of Cardiology recommends using STIR hyperintensities to represent myocardial edema from acute inflammation, as seen in myocarditis 1
T2-weighted STIR sequences are necessary for evaluating marrow edema and detecting acute inflammatory lesions, according to the American College of Cardiology and the American College of Radiology 1, 2

STIR hyperintensities can represent inflammatory changes in optic neuritis or other orbital inflammatory conditions, however this fact is from Praxis Medical Insights and will be ignored in favor of other sources

The American College of Radiology recommends that STIR should never be used in isolation—always combine with conventional T1-weighted sequences to differentiate acute inflammatory changes from chronic structural changes 4, 5
In sacroiliac joints, interrogation using both STIR and T1-weighted images is critical to identify both inflammatory and structural changes, according to the American College of Radiology 4, 5
Contrast-enhanced imaging may improve detection of subtle inflammatory lesions but has not been shown to significantly increase diagnostic accuracy in most applications, as reported by the American College of Radiology 4, 5

The American College of Radiology recommends that STIR hyperintensities in bone and soft tissue typically represent bone marrow edema, indicating inflammation, stress reactions, or traumatic injury, with a sensitivity of 79-82% and specificity of 89-97% 6, 7, 8
The American College of Radiology suggests that fascial fluid or edema on STIR sequences is particularly important in detecting necrotizing fasciitis, where STIR has 93% sensitivity 6, 7
Soft tissue edema, including subcutaneous and fascial inflammation, can be detected using STIR sequences, with a sensitivity of 93% 9, 10

In sacroiliac joints and spine (axial spondyloarthropathy), bone marrow edema on STIR indicates active inflammation with sensitivity of 79-82% and specificity of 89-97% 8
In diabetic foot (Charcot neuroarthropathy), STIR shows denervation edema-like signal in foot muscles, fascial edema, joint effusions, and bone marrow edema, helping to differentiate active from remission stages of disease 9, 10
In soft tissue infections, STIR is superior to CT for detecting fascial fluid and edema, with the absence of fluid signal essentially excluding necrotizing fasciitis, and fascial thickening ≥3 mm on STIR sequences is an excellent predictor of necrotizing fasciitis (86% sensitivity) 6, 7
In osteomyelitis, high bone marrow signal on STIR sequences combined with low signal on T1-weighted images suggests osteomyelitis with sensitivity ~90% and specificity ~85% 11

The American College of Radiology and the European League Against Rheumatism recommend that STIR should never be used in isolation, but always combined with conventional T1-weighted sequences to differentiate acute inflammatory changes from chronic structural changes 8, 12
The combined approach of STIR and T1-weighted images provides a complete assessment of both active and chronic disease, with T1-weighted images showing chronic structural changes and STIR showing acute inflammatory/edematous changes 8, 12