Early Evaluation of the Chemosensitivity in a Rabbit Localized and Solitary VX2 Lung Cancer Model With 18F-FDG PET/CT

Objectives To investigate whether ¹⁸F-FDG PET/CT could be used for early evaluation of chemosensitivity in vivo.

Methods Establish a localized and solitary VX₂ lung cancer rabbit model by CT-guided double-needle coaxial puncturing technique. 23 rabbits with localized and solitary VX2 tumors whose maximum diameter were about 1 cm were recruited and treated by intravenous administration of cisplatin (4mg/kg). ¹⁸F-FDG PET/CT was performed the day before treatment and at day 3, day7 afterward. Maximum standardized uptake value (SUVmax) were analyzed. All 23 rabbits were sacrificed for histological examination. Based on whether the tumor cell necrosis rate is higher than 90% or not, the rabbits were divided into sensitive group and insensitive group. The evaluation performance of the change from the pretherapy SUVmax values in the differentiation between sensitive and insensitive was evaluated using receiver operating characteristic (ROC) analysis.

Results On day 3, the SUVmax and the corresponding SUVmax_{(pre-day 3)}/SUVmax_pre was 3.16±0.72 and -40.4%±48.2% in sensitive group, 4.01±0.8 and -17.1%±36.3% in insensitive group, respectively, there were no significantly difference between the two groups (P>0.05 of both). On day 7, the SUVmax and SUVmax _(pre-day7)/SUVmax_pre were 2.85±1.87 and 16.8%±51.2% in sensitive, 5.85±1.42 and -46.5%±27.4% in insensitive group, there were significantly difference between the two groups (P<0.01 of both). There were no significant difference in inflammatory cells was seen between the sensitive and insensitive group on day 7 (P>0.05). When SUVmax_{(day0 - day7)}/SUVmax_pre equal or greater than -1.95% was considered for chemosensitivity, a sensitivity of 72.7 %, specificity of 100% and an area under the ROC curve of 0.833 (95% CI, 0.644-1.023) were achieved.

Conclusions In rabbit VX2 lung cancer model, the ¹⁸F-FDG PET/CT showed that the SUVmax and SUVmax _{(pre-day 7)}/SUVmax_pre in sensitive group was significantly lower than that in insensitive group. This finding suggests that ¹⁸F-FDG PET/CT might be used for early evaluation of the chemosensitivity within 7 days after chemotherapy. KEY WORDS: ¹⁸F-FDG PET/CT, cisplatin, early evaluation, chemosensitivity, VX2 tumor