Comparing Whole-Body Diffusion-weighted MRI to Conventional Imaging: Staging Pediatric Bone and Soft-Tissue Sarcomas.

Area of Science:

• Oncology
• Radiology
• Medical Imaging

Background:

• Accurate staging of pediatric sarcomas is crucial for treatment planning and prognosis.
• Conventional staging methods, including PET/CT, have limitations in sensitivity and specificity for detecting metastatic disease.

Purpose of the Study:

• To assess the agreement between whole-body diffusion-weighted imaging (WB-DWI) MRI and conventional staging in newly diagnosed pediatric sarcomas.
• To compare the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of WB-DWI versus conventional imaging (including PET/CT) for lesion detection.

Main Methods:

• Prospective single-center study of 47 pediatric sarcoma patients (Ewing sarcoma, osteosarcoma, rhabdomyosarcoma).
• Participants underwent both conventional staging and research-only WB-DWI MRI.
• Biopsy or clinical follow-up served as the reference standard; lesion detection was compared between WB-DWI and PET/CT by blinded radiologists.

Main Results:

• WB-DWI demonstrated 91.5% agreement with conventional staging.
• WB-DWI showed significantly higher sensitivity (65.5% vs. 30.2%) but lower specificity (66.4% vs. 86.7%) compared to PET/CT for lesion detection (P < .001).
• WB-DWI identified more than double the number of malignant bone/bone marrow and lymph node sites compared to PET/CT.

Conclusions:

• WB-DWI MRI is a valuable tool for staging pediatric sarcomas, showing high agreement with conventional methods.
• WB-DWI offers improved sensitivity for detecting metastatic lesions, potentially leading to more comprehensive staging and tailored treatment strategies.
• While WB-DWI has lower specificity than PET/CT, its enhanced sensitivity makes it a promising addition to the staging armamentarium for pediatric sarcomas.