Regarding stress fractures,
1. Plain radiographs eventually pick up to 90% of stress fractures
2. Bone scintigraphy is sensitive and specific method of diagnosing stress fractures
3. CT is less sensitive than bone scintigraphy is the early diagnosis of stress fracture
4. T1WI are most sensitive sequences in the diagnosis of early stress injury
5. Fracture line in stress fracture is typically oriented perpendicular to the cortex
Answers: F, F, T, F, T
Notes: Plain radiographs detect 15% of early fractures and eventually pick up to 50% of stress fractures. Bone scintigraphy is sensitive but not a specific method of diagnosing stress fractures as infection, necrosis and tumors can mimic stress fractures. Fluid sensitive sequences (STIR or fat-sat T2WI) are most sensitive MR sequences in early detetction of stress injuries and T1WI better demonstrate advanced fractures.
Reference: Datir AP et al. Stress-related bone injuries with emphasis on MRI.Clinical Radiology Volume 62 Pages 828-836
