Imaging for Muscle Strain (Pulled Muscle)
For most muscle strains, no imaging is necessary—diagnosis is clinical based on history and physical examination, and initial radiographs are only needed to exclude fracture if there is significant trauma or bony tenderness. 1
Initial Approach
- Start with plain radiographs only if you suspect a fracture (significant trauma mechanism, point tenderness over bone, inability to bear weight) to rule out competing bony diagnoses 2
- Most muscle strains are diagnosed clinically without any imaging—the history of acute pain during strenuous activity involving eccentric muscle contraction is typically sufficient 1
- Physical examination findings of localized tenderness, swelling, and pain with passive stretch or active contraction confirm the diagnosis 1
When Advanced Imaging Is Indicated
Order MRI (without contrast) if:
- Diagnosis is uncertain and you need to differentiate muscle strain from other pathology 1, 3
- You're evaluating a professional athlete where precise injury characterization affects return-to-play decisions 3
- Surgical planning is being considered 3
- The injury involves deep or proximal muscle groups that are difficult to assess clinically 3
- You need prognostic information about severity and expected recovery time 3
MRI vs Ultrasound for Muscle Injuries
Ultrasound is the preferred first-line imaging modality when imaging is needed for most muscle strains due to its high spatial and contrast resolution, lower cost, and dynamic capability 3. Ultrasound can:
- Localize the injury site (myofascial, musculotendinous, or intratendinous) 3
- Identify tears affecting the intramuscular tendon, which have worse prognosis 3
- Provide real-time dynamic assessment 4
MRI should be reserved for:
- Professional athletes requiring detailed characterization 3
- Deep or proximal muscle groups not well-visualized by ultrasound 3
- Surgical planning 3
- When differential diagnosis requires evaluation of other structures 3
What Imaging Shows in Muscle Strains
- Location: Disruption occurs predictably at the myotendinous junction 5
- Fluid collection: Accumulates at the disruption site and dissects along epimysium and subcutaneous tissue 5
- Edema pattern: MRI demonstrates extensive signal changes consistent with edema and inflammation in muscle tissue remote from the myotendinous junction 5
- Follow-up imaging: Can demonstrate atrophy, fibrosis, and calcium deposition in chronic cases 5
Common Pitfalls to Avoid
- Don't order imaging reflexively—most muscle strains are straightforward clinical diagnoses that don't require confirmation with imaging 1
- Don't confuse muscle strain with stress fracture—if clinical suspicion for stress fracture exists (insidious onset, point tenderness over bone, pain with percussion), follow stress fracture imaging algorithms starting with radiographs then MRI 6
- Don't order MRI with contrast—it provides no additional benefit for muscle strain evaluation 6
- Avoid CT for muscle injuries—it involves radiation and is inferior to both ultrasound and MRI for soft tissue characterization 3, 2