Multi-parametric magnetic resonance imaging and CT characteristics and the pathologic basis of monostotic fibrous dysplasia

Purpose: To improve the diagnostic accuracy of monostotic fibrous dysplasia (MFD) and identifying its pathological basis by comparing multi-parametric magnetic resonance imaging (mp-MRI) and CT findings. Materials and methods: In total, this study included 55 patients with MFD. Among the 42 cases with MRI, 29 cases under-went diffusion-weighted imaging (DWI) examination, 15 cases underwent contrast-enhanced MR imaging, and 43 cases underwent plain CT scanning. We compared the morphological characteristics between mp-MRI and basic CT features to combine the radiological features with pathological findings. Results: Fifty-five cases of MFD showed expansive bone destruction (43/55, 78.2%) and slightly hyperintensity or hyperintensity lesions (41/42, 97.6%) with low-signal sclerosing margin (29/42, 69.0%) that were found on T2-weighted imaging. DWI showed hyperintensity (27/29, 93.1%), and the average apparent diffusion coefficient (ADC) value was 1.38 +/- 0.42x10(-3) mm(2)/s. The ground-glass component on T2-weighted imaging was slightly hyperintense or hyperintense (29/29, 100%), with mild or moderate enhancement in 2 cases each (2/15, 13.3%) and obvious enhancement in 11 cases (11/15, 73.4%). Secondary aneurysmal bone cysts were seen in 3 cases (3/55, 5.5%). CT imaging showed ground-glass density (41/43, 95.3%) and a high-density sclerosis ring at the margin (35/43, 81.4%). Showing pathological proof, the normal cancellous bone was replaced with abnormal fibrous tissue. Conclusions: MFD has characteristic mp-MRI findings, such as hyperintensity on T2-weighted imaging inside lesions with a low signal sclerosing margin, hyperintensity on DWI, higher ADC value, and obvious enhancement. MRI can provide more information about pathological features and imaging findings of MFD than radiography and CT, and is an important diagonostic supple-mentation to use radiography and CT.