Evaluation of tumour necrosis during chemotherapy with diffusion-weighted MR imaging: preliminary results in osteosarcomas.
BACKGROUND
During successful chemotherapy of osteosarcomas tumour size does not diminish significantly because the therapy has limited impact on the mineralized matrix of the tumour. Treatment response is considered successful if, histologically, more than 90% of tumour cells show necrosis.


OBJECTIVE
To determine if osteosarcomas change their water diffusion during preoperative chemotherapy in relation to the amount of tumour necrosis.


METHODS
Eight patients (age 11-19 years) with histologically proven limb osteosarcoma underwent T1-weighted, fat-suppressed T2-weighted and contrast-enhanced T1-weighted spin-echo imaging together with diffusion-weighted EPI sequences (b = 700) at 1.5 T before and after five cycles of standard chemotherapy. Tumour volume and apparent diffusion coefficient (ADC) maps were calculated before and after chemotherapy. The degree of tumour necrosis after chemotherapy was assessed using the histological Salzer-Kuntschik classification (grades 1-6).


RESULTS
During chemotherapy, the ADC values of osteosarcomas changed significantly. The ADC of untreated tumour was 2.1 +/- 0.4 x 10(-3) mm(2)/s (mean +/- SD) (95% CI 1.6-2.0). The ADC of chemotherapy-treated sarcomas was 2.5 +/- 0.4 x 10(-3) mm(2)/s (95% CI 1.8-2.2). Necrotic areas, which were confirmed by macroscopic examination, showed ADC values up to 2.7 x 10(-3) mm(2)/s. Four patients with little viable tumour tissue within the neoplasm (Salzer-Kuntschik grades 1-2) had an increase in ADC of 0.4 up to 0.7 x 10(-3) mm(2)/s. Four patients with larger areas of viable tumour (Salzer-Kuntschik grade 4) showed a lesser increase in ADC of 0.0 up to 0.3 x 10(-3) mm(2)/s. The differences in ADC values in tumour tissue before and after chemotherapy were highly significant (P = 0.01).


CONCLUSIONS
During chemotherapy of osteosarcomas, tumour ADC changes are related to the degree of tumour necrosis.
Uhl
Markus
M
Department of Radiology, University Hospital, Hugstetterstr 55, 79104 Freiburg, Germany. Markus.Uhl@uniklinik-freiburg.de
Saueressig
Ulrich
U
Koehler
Gabriele
G
Kontny
Udo
U
Niemeyer
Charlotte
C
Reichardt
Wilfried
W
Ilyasof
Kamil
K
Bley
Thorsten
T
Langer
Mathias
M
D000293:Adolescent; D000328:Adult; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000188:drug therapy / Q000473:pathology*; D002648:Child; D003287:Contrast Media / Q000008:administration & dosage; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D009336:Necrosis; D012516:Osteosarcoma / Q000188:drug therapy / Q000473:pathology*; D010865:Pilot Projects; D011237:Predictive Value of Tests
D000970:Antineoplastic Agents; D003287:Contrast Media; D019786:Gadolinium DTPA