¹⁸F-FDG PET SUVmax as an indicator of histopathologic response after neoadjuvant chemotherapy in extremity osteosarcoma.
OBJECTIVE
This study evaluated the usefulness of the maximum standardized uptake value (SUVmax) as a measure of histologic response to neoadjuvant chemotherapy in patients with extremity osteosarcoma. The correlation between [(18) F]FDG PET SUVmax values and histologic response to preoperative chemotherapy was also assessed prospectively using PET/MRI.


METHODS
A total of 26 consecutive patients with high-grade osteosarcoma were prospectively enrolled. All patients underwent parallel PET and MRI scans before and after neoadjuvant chemotherapy. Using the PET and MRI images and pathologic mapping, we assessed the percentage necrosis by histology at the highest metabolic activity point in the tumors. This was defined as the minimum histologic response. The predictive values of SUVmax before (SUV1) and after (SUV2) chemotherapy and the SUV change ratio were determined. Correlations were also investigated among SUV2, minimum histologic response and histologic response.


RESULTS
Histologically, 13 patients were classified as good responders and 13 as poor responders. Patients with an SUV2 of >5 showed a poor histologic response. A significant correlation was found between SUV2 and histologic response (Spearman's rho -0.642; P < 0.001), and SUV2 and histologic response were both found to be significantly correlated with minimum histologic response (Spearman's rho -0.515 and 0.911; P = 0.007 and P < 0.001, respectively).


CONCLUSIONS
A SUVmax of more than 5 after neoadjuvant chemotherapy identified the majority of histologic nonresponders (sensitivity 61.3 %, PPV 88.9 %). Tumor necrosis at the point of maximum metabolic activity was found to be significantly correlated with the histologic response of entire resected specimen.
Department of Orthopedic Surgery, Korea Cancer Center Hospital, Seoul, South Korea.
Chang-Bae
CB
Kong
Byung Hyun
BH
Byun
Ilhan
I
Lim
Chang Woon
CW
Choi
Sang Moo
SM
Lim
Won Seok
WS
Song
Wan Hyeong
WH
Cho
Dae-Geun
DG
Jeon
Jae-Soo
JS
Koh
Ji Young
JY
Yoo
Soo-Yong
SY
Lee
D000293:Adolescent; D000328:Adult; D002648:Child; D005121:Extremities / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D012516:Osteosarcoma / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology*; D049268:Positron-Emission Tomography; D012372:ROC Curve; D016896:Treatment Outcome; D055815:Young Adult
D019788:Fluorodeoxyglucose F18