Osteosarcoma after chemotherapy: evaluation with contrast material-enhanced subtraction MR imaging

Area of Science:

• Oncology
• Radiology
• Medical Imaging

Background:

• Osteosarcoma treatment response is crucial for patient outcomes.
• Accurate assessment of chemotherapy effectiveness is vital for guiding treatment decisions.

Purpose of the Study:

• To evaluate a new magnetic resonance (MR) technique, gadolinium-enhanced subtraction MR imaging, for assessing chemotherapy response in osteosarcoma.
• To correlate MR imaging findings with histopathologic results in differentiating responders from nonresponders.

Main Methods:

• Ten patients with lower extremity osteosarcoma underwent MR imaging before surgery.
• Gadolinium-enhanced subtraction MR imaging was performed by subtracting precontrast images from postcontrast T1-weighted images at 1.5 minutes post-injection.
• Radiologists and histopathologists independently assessed tumor viability to classify responders and nonresponders.

Main Results:

• Four of 10 osteosarcomas were classified as good responders, showing nonenhancing masses or small nodules (< or = 3 mm) on subtraction MR.
• Histopathology confirmed these as good responders with <3% viable tumor.
• Six of 10 osteosarcomas were classified as nonresponders, appearing as enhancing masses (>3 mm) on MR, with 18-43% viable tumor cells found histopathologically.

Conclusions:

• Gadolinium-enhanced subtraction MR imaging is a promising technique for evaluating chemotherapy response in osteosarcoma.
• The technique effectively differentiates responders from nonresponders by assessing tumor enhancement and viability.