Imaging diagnosis of osteoid osteoma / 中华放射学杂志

ABSTRACT

Objective To analyze the X -ray, CT, and MR imaging findings in osteoid osteoma. Methods Forty-eight cases of osteoid osteoma proved by surgical pathology were collected, including 33 males and 15 females. Among the 48 cases, all patients had plane films, 32 were imaged with CT scanning, 10 with MR imaging, and 8 with all three techniques. The imaging findings of osteoid osteoma and the ability of X-ray, CT, and MRI in demonstrating the nidus and the surrounding reaction were analyzed. Results The imaging manifestations of osteoid osteoma revealed a circular or oval nidus with different bone sclerosis around the nidus. The diameters ranged from 0.4 cm to 1.7 cm, with the average of 9.7 cm. There were also soft tissue and bone morrow edema around the nidus or distinct effusion of joint on MR imaging in all 10 cases. Among 48 cases, only 37 cases showed nidus on plane film. All 32 cases with CT scanning showed nidus. The display ratios of nidus were 77% for X-ray and 100% for CT, respectively. 10 cases with MR imaging could be diagnosed correctly. But the nidus could be affirmed in only 8 cases, and the nidus was affirmed by comparing with plane film or CT in the other 2 cases. Conclusion Nidus is the key in diagnosing the osteoid osteoma correctly. Plane film is still an important checking method for osteoid osteoma. CT scan is the best method to demonstrate the nidus. MRI can demonstrate the soft tissue and bone morrow edema around the nidus sensitively, but probably lead to an incorrect diagnosis. Combining with X-ray or CT, MRI can make an accurate diagnosis.