The Angle of Louis. A potential pitfall ("Louie's Hot Spot") in bone scan interpretation

Evaluation of 100 consecutive Tc-99m MDP bone scans revealed in 36 patients a well defined area of increased accumulation of radiotracer at the Angle of Louis--the palpable ridge along the anterior surface of the sternum at the fibrocartilaginous junction of the sternum and manubrium. Twenty-five of the 36 patients had comparison radiographs; all were normal. None had sternal pain or a prior history of chest trauma. Increased uptake at the Angle of Louis ("Louie's Hot Spot") is a relatively common finding (36%) and should be recognized as a normal bone scan finding. It should not be confused with increased uptake due to an osseous abnormality, i.e., metastasis, degenerative disease, trauma, etc.