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Tumor T1 for early chemotherapeutic response evaluation in patients with osteosarcoma with correlation to histological necrosis
Esha Baidya Kayal1, Nikhil Sharma1, Raju Sharma2, Sameer Bakhshi3, Devasenathipathy Kandasamy2, and Amit Mehndiratta1,4
1Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India, 2Radio diagnosis, All India Institute of Medical Sciences Delhi, New Delhi, India, 3Department of Medical Oncology, Dr. B.R. Ambedkar Institute-Rotary Cancer Hospital (IRCH), All India Institute of Medical Sciences Delhi, New Delhi, India, 4Department of Biomedical Engineering, All India Institute of Medical Sciences Delhi, New Delhi, India
Mean and skewness of tumor T1 values in osteosarcoma may characterize chemotherapeutic changes in osteosarcoma and might be useful as non-invasive imaging markers of chemotherapy response.

Figure 2: Images are from A. a representative patients (M, 15 years) from Response group with osteosarcoma in right Tibia. B. a representative patients (M, 14 years) from Non-Response group with osteosarcoma in right femur.

For A and B: a, c) Estimated T1 maps and b, d) Histogram of T1 values in tumor at baseline and follow-up respectively.

A comparatively higher reduction tumor T1 can be observed after chemotherapy for Responder than Non-responder. Histogram of tumor T1 for Responder was low picked at baseline and became more positively skewed after chemotherapy than Non-responder.

Figure 3: ROC curve analysis using statistically significant (p<0.5) histogram parameters of T1 value in tumor a) at baseline and b) its relative percentage changes (Δ) at follow-up.

a) At baseline T1-mean and T1-skewness in combination produced AUC=0.86, sensitivity=88%, specificity=72% in identifying chemotherapeutic response.

b) After chemotherapy, ΔT1-mean and ΔT1-skewness in combination produced AUC=0.92, sensitivity=89%, specificity=92% in identifying chemotherapeutic response.