Role of Ultrasonography and MRI in Acute Hamstring Strains: Diagnostic and Prognostic Insights

Background/Objectives: Hamstring strain injuries are common in elite athletes and affect return-to-sport timeline. Although magnetic resonance imaging (MRI) is the gold standard for assessing injury severity, ultrasonography (US) is a more accessible and cost-effective alternative. This study aimed to evaluate the agreement between US and MRI in the diagnosis of hamstring injuries and their prognostic value in predicting recovery. Methods: This retrospective study included elite athletes with acute first-time hamstring strains who underwent both MRI and US within five days after injury. The injuries were classified according to location (muscle belly, musculotendi-nous junction, or tendon) and severity (modified Peetrons classification). The agree-ment between imaging findings and return-to-sport timelines was analyzed. Results: US demonstrated 70% agreement with MRI in identifying injury locations, with the highest concordance for muscle belly (90%) and musculotendinous junction (80%) in-juries but lower accuracy for tendons (60%). Recovery times differed significantly by location and severity (p < 0.01), with tendon grade 3 injuries requiring the longest re-covery (383 days), while muscle belly injuries had the shortest recovery (16 days). Musculotendinous junction grade 2, tendon grade 1, and tendon grade 2 injuries had similar recovery durations (57–65 days). Conclusions: High-resolution US is a reliable diagnostic tool for muscle belly and musculotendinous junction injuries; however, MRI remains essential for high-grade tendon injuries. US serves as a first-line imaging mo-dality, with MRI reserved for cases that require a detailed prognostic assessment. These findings provide guidance for optimizing imaging strategies for hamstring inju-ry management.