Role of diffusion-weighted MRI in differentiating between benign and malignant bone lesions: a prospective study

To evaluate the ability of diffusion-weighted magnetic resonance imaging (DW-MRI) to differentiate between benign and malignant bony tumours.

This prospective study was conducted from October, 2018 to December, 2019. The study included 62 patients (37 male and 25 female) with clinically suspected bony lesions referred to the Radiology Department. Patients underwent clinical examination, radiography, computed tomography (CT), and ultrasonography examinations. MRI studies were conducted using a 1.5-T MRI machine, and post-processing analysis was done using a Philips Extended MRI workspace workstation.

The mean apparent diffusion coefficient (ADC) value of benign lesions ranged between 0.85 × 10^-3 and 2.44 × 10^-3 mm²/s. The lowest ADC values were measured in a giant cell tumour and in an inclusion epidermoid cyst (0.85 × 10^-3 and 0.93 × 10^-3 mm²/s, respectively). The highest measurement was in bony cysts (2.44 × 10^-3 mm²/s) followed by osteoid osteoma (2.2 × 10^-3 mm²/s) and osteochondroma (1.85 × 10^-3 mm²/s). Amongst malignant lesions, ADC values ranged from 0.42 × 10^-3 to 2.4 × 10^-3 mm²/s. The lowest value was measured in malignant round cell tumour Ewing's/primitive neuroectodermal tumour (PNET), and the highest was measured in conventional chondrosarcoma. Metastatic lesions were observed in 11 patients with a mean ADC value of 0.71 × 10^-3 mm²/s, followed by osteosarcoma in six patients with a mean ADC value of 0.74 × 10^-3 mm²/s.

There was a significant difference between the mean, minimum, and maximum ADC values of benign and malignant tumours. The present findings indicate that the best cut-off ADC range to predict malignancy is 0.78-0.86 × 10^-3 mm²/s, with a sensitivity of 89.47%, specificity of 97.22%, and accuracy of 94.55%.