Abstract
ObjectiveThe purpose of this study was to determine whether chemical-shift magnetic resonance imaging (MRI) could be useful in the diagnosis of osteoid osteoma when clinical and radiological tumor features are inconclusive.Materials and MethodsThis retrospective study included 17 patients who underwent chemical-shift MRI for the evaluation of osteoid osteoma. For all patients, two musculoskeletal radiologists independently recorded signal intensities on in-phase and out-of-phase images in the nidus of the tumor, in abnormal-intensity bone marrow surrounding the lesion, and in normal-appearing bone marrow. For each region, relative signal intensity ratios were calculated by dividing out-of-phase by in-phase values. Relative ratios > 1 were considered indicative of neoplastic lesions. Statistical analysis was carried out to analyze the sample. Inter-observer and intra-observer agreement for each imaging method were assessed using intraclass correlation coefficients according to the Fleiss method and a value > 0.65 was considered to indicate substantial agreement.ResultsThe mean relative signal intensity ratios were 1.2 (range, 0.9-1.4) for the nidus and 0.35 (range, 0.11-0.66) for the surrounding tissue; these values differed significantly from the relative signal-intensity ratios for normal-appearing bone marrow (p < 0.05).ConclusionChemical-shift MRI is useful for the diagnosis and evaluation of osteoid osteoma.
Highlights
Osteoid osteoma is the third most common primary benign skeletal neoplasm; it occurs frequently in young patients and shows a predilection for males[1]
Osteoid osteoma is an osteolytic defect with sharp margins and a vacularized nidus, which may be surrounded by marginal sclerosis and cortical thickening[2,3,4,5,6,7]
The nidus can be identified on computed tomography (CT), CT has been associated with disadvantages such as a high radiation dose[10,11]
Summary
Osteoid osteoma is the third most common primary benign skeletal neoplasm; it occurs frequently in young patients and shows a predilection for males[1]. Osteoid osteoma is an osteolytic defect with sharp margins and a vacularized nidus, which may be surrounded by marginal sclerosis and cortical thickening[2,3,4,5,6,7]. The imaging features of osteoid osteoma are frequently confused with those of Ewing’s sarcoma or chronic osteomyelitis, especially Brodie’s abscess, because of the extensive periosteal reaction, cortical thickening, and sclerosis[9]. Magnetic resonance imaging (MRI) can be used for this purpose, it does not enable a conclusive diagnosis in the majority of cases[10,12,13,14,15,16]
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