Hubless keypoint-based 3D deformable groupwise registration.

We present a novel algorithm for Fast Registration Of image Groups (FROG), applied to large 3D image groups. Our approach extracts 3D SURF keypoints from images, computes matched pairs of keypoints and registers the group by minimizing pair distances in a hubless way i.e. without computing any central mean image. Using keypoints significantly reduces the problem complexity compared to voxel-based approaches, and enables us to provide an in-core global optimization, similar to the Bundle Adjustment for 3D reconstruction. As we aim to register images of different patients, the matching step yields many outliers. Then we propose a new EM-weighting algorithm which efficiently discards outliers. Global optimization is carried out with a fast gradient descent algorithm. This allows our approach to robustly register large datasets. The result is a set of diffeomorphic half transforms which link the volumes together and can be subsequently exploited for computational anatomy and landmark detection. We show experimental results on whole-body CT scans, with groups of up to 103 volumes. On a benchmark based on anatomical landmarks, our algorithm compares favorably with the star-groupwise voxel-based ANTs and NiftyReg approaches while being much faster. We also discuss the limitations of our approach for lower resolution images such as brain MRI.

Use of Amifostine in the Therapy of Osteosarcomain Children and Adolescents

Amifostine protects normal tissue from the cytotoxic damage induced by radiation and chemotherapy. In this study, 39 consecutive newly diagnosed children with osteosarcoma were assessed; 20 received amifostine and 19 did not. The chemotherapy regimen included an induction phase of three cycles of cisplatin (100 mg/m2), carboplatin (500 mg/m2), and doxorubicin (60 mg/m2), followed by surgery. Alternating cycles of cisplatin/ifosfamide (9 mg/m2), ifosfamide/doxorubicin, carboplatin/doxorubicin, and ifosfamide/carboplatin were administered every 3 weeks to complete 26 weeks of treatment. Amifostine was administered 15 minutes before the infusions of cisplatin and carboplatin in a total of 193 infusions. Side effects during infusions and renal, hearing, and bone marrow toxicities were evaluated and compared between the two groups. Hypotension was observed in 28 (14.5%) infusions. No patient required discontinuation of therapy. Fewer than two episodes of vomiting occurred in 130 (71%) infusions and two to five episodes occurred in 51 (28%) infusions, and no patient had grade 4 toxicity. There was no difference between the two groups regarding renal toxicity (creatinine clearance). Neutropenia and leukopenia were significantly less frequent in the amifostine group. No difference was observed in platelet and hearing toxicities. Amifostine was well tolerated in doses of 740 mg/m2 in children and adolescents, and myelotoxicity was less severe in the amifostine group. This was a pilot study for further evaluation in a larger randomized trial.

Activity of intraarterial carboplatin as a single agent in the treatment of newly diagnosed extremity osteosarcoma.

BACKGROUND: Chemotherapy has dramatically improved the rates of cure and survival of patients with localized and metastatic osteosarcoma. Nonetheless, the number of chemotherapeutic agents active against osteosarcoma is limited to doxorubicin, cisplatin, high-dose methotrexate, and ifosfamide. Carboplatin, a cisplatin analogue, has been tested as a single agent in patients with recurrent osteosarcoma or as part of multiagent chemotherapy in newly diagnosed patients. PROCEDURE: We tested the activity and toxicity of two cycles of intraarterial carboplatin as a "window therapy" (600 mg/m2 per cycle) in 33 consecutive patients with extremity osteosarcoma before the start of multiagent chemotherapy. Response was based on clinical (tumor diameter, local inflammatory signs, and range of motion) and radiological parameters (plain local films and arteriographic studies prior to drug administration). RESULTS: Patients' age ranged between 8 and 18 years (median age 13 years). Primary tumor originated from the femur (15 patients), tibia (10 patients), fibula (4 patients), humerus (3 patients), and calcaneus (1 patient). Only 7 patients (21%) had metastatic disease at diagnosis (5 in the lung and 2 in other bones). A favorable clinical and radiological response was documented in 81% and 73% of the patients, respectively. Clinical and radiological progression occurred in 12% and 9% of the patients, respectively. Seventeen of the patients remain alive and disease-free. Survival and event-free survival at 3 years for nonmetastatic patients are 71% (SE = 9%) and 65% (SE = 9%), respectively; for metastatic patients, the figures are 17% (SE = 15%) and 14% (SE = 13%), respectively. CONCLUSIONS: We conclude that carboplatin is an active agent in the treatment of newly diagnosed extremity osteosarcoma.