Low T1 bone lesions or T1 hypointense bone lesions are radiological terms to categorize bone lesions according to their visually perceived low signal on T1 weighted images. Apart from the usual description of a bone lesion seen on MRI they are used to categorize incidentally found solitary bone lesions in the Bone Reporting and Data System (Bone-RADS) 1.
The lesion signal intensity on T1 weighted images is usually compared to the adjacent skeletal muscle or intervertebral disc 1 and lesions with similar or lower signal intensity are referred to as low T1 bone lesions or T1 hypointense bone lesions 1,2.
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Differential diagnosis
The differential diagnosis of low T1 lesion can be narrowed down according to the following factors 1-3:
the associated T2 signal also evaluated in relation to the skeletal muscle or adjacent intervertebral disc
the presence of specific features indicating an aggressive nature of the lesion
focal lesions versus multifocal lesions or diffuse disease
The differential diagnosis comprises a vast list of bone lesions including the following 1-4:
-
high T2 signal
indeterminate bone lesion
atypical intraosseous hemangioma
multiple myeloma (multifocal)
lymphoma (usually multifocal)
-
low T2 signal
bone cement
myelofibrosis (multifocal)
lymphoma (usually multifocal)
Practical points
low T1 bone lesions with aggressive features are generally considered suspicious or in need of treatment
See also
solitary lucent bone lesion
solitary mixed density bone lesion
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