Evaluation of static and dynamic MRI for assessing response of bone sarcomas to preoperative chemotherapy: Correlation with histological necrosis.
OBJECTIVE
Preoperative chemotherapy plays a key role in management of bone sarcomas. Postoperative evaluation of histological necrosis has been the gold standard method of assessing response to preoperative chemotherapy. This study was done to evaluate the efficacy of static and dynamic magnetic resonance imaging (MRI) for assessing response preoperatively.


METHODS
Our study included 14 patients (12 osteosarcomas and 2 malignant fibrous histiocytomas) with mean age of 21.8 years, treated with preoperative chemotherapy followed by surgery. They were evaluated with static and dynamic MRI twice, before starting chemotherapy and again prior to surgery. Change in tumor volume and slope of signal intensity - time curve were calculated and correlated with percentage of histological necrosis using Pearson correlation test.


RESULTS
The change in dynamic MRI slope was significant (P = 0.001). Also, ≥60% reduction in slope of the curve proved to be an indicator of good histological response [positive predictive value (PPV) =80%]. Change in tumor volume failed to show significant correlation (P = 0.071). Although it showed high negative predictive value (NPV = 85.7%), PPV was too low (PPV = 57.14%).


CONCLUSIONS
Dynamic MRI correctly predicts histological necrosis after administration of preoperative chemotherapy to bone sarcomas. Hence, it can be used as a preoperative indicator of response to neoadjuvant chemotherapy. On the other hand, volumetric assessment by static MRI is not an effective predictor of histological necrosis. This study proves the superiority of dynamic contrast-enhanced study over volumetric study by MRI.
Department of Orthopaedics, Max Super Speciality Hospital, New Delhi, India.
Priyadarshi
P
Amit
Department of Orthopaedics, Sport Injury Centre, Safdarjung Hospital, New Delhi, India.
Atul
A
Malhotra
Department of Orthopaedics, Sport Injury Centre, Safdarjung Hospital, New Delhi, India.
Rahul
R
Kumar
Department of Radiodiagnosis, Sport Injury Centre, Safdarjung Hospital, New Delhi, India.
Lokesh
L
Kumar
Department of Orthopaedics, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India.
Dilip Kumar
DK
Patro
Department of Radiodiagnosis, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India.
Sundar
S
Elangovan
Dynamic MR; MR; histological necrosis; malignant fibrous histiocytoma; osteosarcoma; preoperative chemotherapy