Giant Cell Tumors of the Bone: Changes in Image Features after Denosumab Administration

Abstract

Purpose:To assess the clinical importance in the feature change in giant cell tumors of the bone (GCTB) after denosumab treatment, detected by MRI.Methods:In 12 patients, MRI and CT of GCTB obtained before and after the treatment retrospectively compared. The tumor size, the signal intensity (SI) ratio between the solid part of the GCTB and muscle, cystic part size, gadolinium enhancement and apparent diffusion coefficient (ADC) value were measured on MRI. The bone formation in the tumor was observed on CT and X-ray.Results:The mean number of denosumab injections was 19 ± 10. The follow-up period was up to 2 years. One case showed partial remission, while the other 11 cases were stable. A mean SI ratio on T2-weighted image statistically significantly decreased from 3.9 to 1.9 after the treatment. A cystic component in the tumor was observed in five cases before the treatment, and the diameter of the cystic part decreased after the treatment in 80% of cases (4/5). All the tumors showed contrast enhancement on T1-weighted image pre- and post-treatment (11/11). The averaged ADC values were 1.52 × 10−3 mm2/s before and 1.44 × 10−3 mm2/s after the treatment (P = 0.63). Bone formation in the tumor was observed in 58% of cases (7/12).Conclusion:The decrease of SI ratio on T2-weighted image, shrinkage of cystic part and bone formation should be regarded as the effectiveness of denosumab treatment despite of no substantial change in the tumor size.

Radiological findings of denosumab treatment for giant cell tumours of bone

“…In accordance with our experience, Oguro et al concluded that both shrinkage of the cystic component in the tumour and a decrease in T2 signal intensity (representing new bone formation) are more useful markers to assess treatment response [33]. Contrast enhancement and DWI/ADC were not found particularly useful; however, the study included only a small number of patients (N = 12) [33]. More research is needed to evaluate the value of contrast enhancement studies before and after denosumab treatment, as dynamic contrast enhancement (mean time intensity curves) may add more information [34].…”

“…Decreased T2-weighted MR signal has previously been described [4,11,21,33] with demonstrable signal change from 7 weeks [11] after commencing denosumab treatment.…”

“…7 and 8). Oguro et al showed that maximum tumour diameter, assessed on T2-weighted images, decreased by 15% on average after 19 months on treatment, which is scored as stable disease according to RECIST [33].…”

“…8 and 9); best appreciated on fluid-sensitive fat-suppressed sequences. Oguro et al found that the cystic component of GCTB significantly decreased in size in 4/5 patients after treatment and is thought to be due to the blocking effect of denosumab on RANKL with resultant suppression of osteoclasts [33]. Fluid-fluid levels in keeping with secondary aneurysmal bone cyst formation have been described to be present in up to 14% of patients with GCTB [18,20].…”

MRI biomarkers in osseous tumors

“…This may be explained as increased water diffusivity due to tissue necrosis, which is the same response to chemotherapy as seen in other malignant bone tumors. In a study of GCT, although only six subjects were evaluated, changes in ADC after denosumab treatment varied . The authors suggested that denosumab induced a variable histological response like that of intermixed bone and fibroblast‐like spindle cells or dense calcification might limit the potential use of ADC.…”