Table 3. Classification of stress fracture as low and high grade based on bone scintigraphy and MRI.

Grade	Bone scintigraphy findings	MRI findings
Low	Irregular uptake and/or a poorly defined area of increased activity, compared with the contralateral side	Bone marrow edema in STIR images, possibly in T2-weighted images
High	Sharply marginated area of increased activity, compared to the other side, usually focal or fusiform in shape	Bone marrow edema on T1- and T2-weighted image with or without a fracture line