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Citation:
Klontzas M, Yap J, Knipe H, Half-moon sign (femoral neck). Reference article, Radiopaedia.org (Accessed on 09 Dec 2023) https://doi.org/10.53347/rID-148761
The half-moon sign describes the morphology of bone marrow edema at the femoral neck on fluid-sensitive MRI sequences, which can be seen in osteoid osteoma or stress fractures 1-3.
Differential diagnosis
-
intra-articular osteoid osteoma
in patients without a history of overuse, it is highly specific and sensitive for the diagnosis of osteoid osteoma 1-3
identification of the sign on MRI should prompt CT examination for the identification of a nidus 1
stress reaction/fracture of the femoral neck in cases with a history of lower limb overuse (e.g. athletes, armed forces members) 4,5
- 1. Klontzas M, Zibis A, Karantanas A. Osteoid Osteoma of the Femoral Neck: Use of the Half-Moon Sign in MRI Diagnosis. AJR Am J Roentgenol. 2015;205(2):353-7. doi:10.2214/AJR.14.13689 - Pubmed
- 2. Gassert F, Hammel J, Hofmann F et al. Detection of Bone Marrow Edema in Patients with Osteoid Osteoma Using Three-Material Decomposition with Dual-Layer Spectral CT. Diagnostics. 2021;11(6):953. doi:10.3390/diagnostics11060953
- 3. Malghem J, Lecouvet F, Kirchgesner T, Acid S, Vande Berg B. Osteoid Osteoma of the Hip: Imaging Features. Skeletal Radiol. 2020;49(11):1709-18. doi:10.1007/s00256-020-03515-8 - Pubmed
- 4. Carra B, Chen D, Bui-Mansfield L. The Half-Moon Sign of the Femoral Neck Is Nonspecific for the Diagnosis of Osteoid Osteoma. AJR Am J Roentgenol. 2016;206(3):W54. doi:10.2214/AJR.15.15610 - Pubmed
- 5. Klontzas M, Zibis A, Karantanas A. Reply to "The Half-Moon Sign of the Femoral Neck Is Nonspecific for the Diagnosis of Osteoid Osteoma.". AJR Am J Roentgenol. 2016;206(3):W55-6. doi:10.2214/AJR.15.15724 - Pubmed
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