Utility of intraoperative magnetic resonance imaging for giant cell tumor of bone after denosumab treatment: a pilot study

Current Concepts in the Treatment of Giant Cell Tumor of Bone: An Update

Curettage is recommended for the treatment of Campanacci stages 1-2 giant cell tumor of bone (GCTB) in the extremities, pelvis, sacrum, and spine, without preoperative denosumab treatment. In the distal femur, bone chips and plate fixation are utilized to reduce damage to the subchondral bone and prevent pathological fracture, respectively. For local recurrence, re-curettage may be utilized when feasible. En bloc resection is an option for very aggressive Campanacci stage 3 GCTB in the extremities, pelvis, sacrum, and spine, combined with 1-3 doses of preoperative denosumab treatment. Denosumab monotherapy once every 3 months is currently the standard strategy for inoperable patients and those with metastatic GCTB. However, in case of tumor growth, a possible malignant transformation should be considered. Zoledronic acid appears to be as effective as denosumab; nevertheless, it is a more cost-effective option. Therefore, zoledronic acid may be an alternative treatment option, particularly in developing countries. Surgery is the mainstay treatment for malignant GCTB.

Information-guided Surgery Centered on Intraoperative Magnetic Resonance Imaging Guarantees Surgical Safety with Low Mortality

Neurosurgery is complex surgery that requires a strategy that maximizes the removal of tumors and minimizes complications; thus, a safe environment during surgery should be guaranteed. In this study, we aimed to verify the safety of brain surgery using intraoperative magnetic resonance imaging (iMRI), based on surgical experience since 2000. Thus, we retrospectively examined 2,018 surgical procedures that utilized iMRI performed in the operating room at Tokyo Women's Medical University Hospital between March 2000 and October 2019. As per our data, glioma constituted the majority of the cases (1,711 cases, 84.8%), followed by cavernous hemangioma (61 cases, 3.0%), metastatic brain tumor (37 cases, 1.8%), and meningioma (31 cases, 1.5%). In total, 1,704 patients who underwent glioma removal were analyzed for mortality within 30 days of surgery and for reoperation rates and the underlying causes within 24 hours and 30 days of surgery. As per our analysis, only one death out of all the glioma cases (0.06%) was reported within the 30-day period. Meanwhile, reoperation within 30 days was performed in 37 patients (2.2%) due to postoperative bleeding in 17 patients (1.0%), infection in 12 patients (0.7%), hydrocephalus in 6 patients (0.4%), cerebrospinal fluid (CSF) leakage in 1 patient, and brain edema in 1 patient (0.06%). Of these, 14 cases (0.8%) of reoperation were performed within 24 hours, that is, 13 cases (0.8%) due to postoperative bleeding and 1 case (0.06%) due to acute hydrocephalus. Mortality rate within 30 days was less than 0.1%. Thus, information-guided surgery with iMRI can improve the safety of surgical resections, including those of gliomas.

State of the Art and New Concepts in Giant Cell Tumor of Bone: Imaging Features and Tumor Characteristics

Giant cell tumor of bone (GCTB) is classified as an intermediate malignant tumor due to its locally aggressive behavior, burdened by high local recurrence rate. GCTB accounts for about 4-5% of all primary bone tumors and typically arises in the metaphysis and epiphyses of the long tubular bones. Mutation of gene H3F3A is at the basis of GCTB etiopathogenesis, and its immunohistochemical expression is a valuable method for practical diagnosis, even if new biomarkers have been identified for early diagnosis and for potential tumor recurrence prediction. In the era of computer-aided diagnosis, imaging plays a key role in the assessment of GCTB for surgical planning, patients' prognosis prediction and post treatment evaluation. Cystic changes, penetrating irregular margins and adjacent soft tissue invasion on preoperative Magnetic Resonance Imaging (MRI) have been associated with a higher rate of local recurrence. Distance from the tumor edge to the articular surface and thickness of unaffected cortical bone around the tumor should be evaluated on Computed Tomography (CT) as related to local recurrence. Main features associated with local recurrence after curettage are bone resorption around the graft or cement, soft tissue mass formation and expansile destruction of bone. A denosumab positive response is represented by a peripherical well-defined osteosclerosis around the lesion and intralesional ossification. Radiomics has proved to offer a valuable contribution in aiding GCTB pre-operative diagnosis through clinical-radiomics models based on CT scans and multiparametric MR imaging, possibly guiding the choice of a patient-tailored treatment. Moreover, radiomics models based on texture analysis demonstrated to be a promising alternative solution for the assessment of GCTB response to denosumab both on conventional radiography and CT since the quantitative variation of some radiomics features after therapy has been correlated with tumor response, suggesting they might facilitate disease monitoring during post-denosumab surveillance.