Value of diffusion-weighted images in differentiating mid-course responders to chemotherapy for osteosarcoma compared to the histological response: preliminary results.
BACKGROUND
Preoperative diffusion-weighted MRI (DW-MRI) has been described as an efficient method to differentiate good and poor responders to chemotherapy in osteosarcoma patients. A DW-MRI performed earlier during treatment could be helpful in monitoring chemotherapy.


OBJECTIVE
To assess the accuracy of DW-MRI in evaluating response to chemotherapy in the treatment of osteosarcoma, more specifically at mid-course of treatment.


METHODS
This study was carried out on a prospective series of adolescents treated for long-bone osteosarcoma. MR examinations were performed at diagnosis (MRI-1), at mid-course of chemotherapy (MRI-2), and immediately before surgery (MRI-3). A DW sequence was performed using diffusion gradients of b0 and b900. The apparent diffusion coefficients (ADC1, ADC2, ADC3, respectively), their differentials (ADC2 - ADC1 and ADC3 - ADC1), and their variation (ADC2 - ADC1/ADC1 and ADC3 - ADC1/ADC1) were calculated for each of these three time points.


RESULTS
Fifteen patients were included. Patients with no increase in ADC showed a poor response to chemotherapy on their histology results. At mid-course, the three calculated values were significantly different between good and poor responders. ADC2 - ADC1 enabled us to detect, with 100% specificity, four out of seven of the poor responders. There was no significant difference in the values at MRI-3 between the two groups.


CONCLUSIONS
DW-MRI performed both at baseline and mid-course of neoadjuvant chemotherapy is an efficient method to predict further histological response of osteosarcoma. This method could be used as an early prognostic factor to monitor preoperative chemotherapy.
Service d'imagerie pédiatrique et prénatale, Hôpital Timone Enfants, 264 Rue Sainte Pierre, 13385, Marseille Cedex 05, France. cbaunin@ap-hm.fr
C
C
Baunin
G
G
Schmidt
K
K
Baumstarck
C
C
Bouvier
J C
JC
Gentet
A
A
Aschero
A
A
Ruocco
B
B
Bourlière
G
G
Gorincour
C
C
Desvignes
N
N
Colavolpe
G
G
Bollini
P
P
Auqier
P
P
Petit
D000293:Adolescent; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D012516:Osteosarcoma / Q000188:drug therapy* / Q000473:pathology*; D010865:Pilot Projects; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D000970:Antineoplastic Agents