Hepatobiliary scintigraphy allows the evaluation of short-term functional toxicity of liver stereotactic body radiotherapy: Results of a pilot study.

PURPOSE: To study the potential of (99m)Tc-Mebrofenin hepatobiliary scintigraphy (HBS) in identifying the short-term variations of liver function after stereotactic body radiotherapy (SBRT) for liver cancers. MATERIAL AND METHODS: We treated with SBRT 3 patients (pts) affected by a cholangiocarcinoma and 3 patient presenting liver metastases (3x15 Gy, 4 pts; 5x8 Gy, 1 pt; 6x5 Gy, 1 pt). All patients received HBS before and 3 months after SBRT, which were co-registered with the simulation CT-scan. Structures corresponding to isodoses from 10-90 Gy were created, with intervals of 10 Gy. Finally, the variations of the mean activity (MBq) in each isodose structure have been calculated. Then, a linear regression analysis was performed. RESULTS: We showed a linear reduction of the activity, significantly related to the delivered dose (p<0.01), and a reduction of the perfusion of 0.78% for each delivered Gy. The linear equation has predictive value of the loss of the function of 96% (R2 = 0.9605). CONCLUSIONS: HBS could improve treatment plans for liver SBRT, by allowing the identification of the liver function variations after SBRT and, potentially, the prediction of remnant liver function after SBRT. These preliminary results should be confirmed on long-term prospective data and larger population.

[(18)F]FDG-PET/CT metabolic parameters as useful prognostic factors in cervical cancer patients treated with chemo-radiotherapy.

BACKGROUND: To compare the prognostic value of different anatomical and functional metabolic parameters determined using [(18)F]FDG-PET/CT with other clinical and pathological prognostic parameters in cervical cancer (CC). METHODS: Thirty-eight patients treated with standard curative doses of chemo-radiotherapy (CRT) underwent pre- and post-therapy [(18)F]FDG-PET/CT. [(18)F]FDG-PET/CT parameters including mean tumor standardized uptake values (SUV), metabolic tumor volume (MTV) and tumor glycolytic volume (TGV) were measured before the start of CRT. The post-treatment tumor metabolic response was evaluated. These parameters were compared to other clinical prognostic factors. Survival curves were estimated by using the Kaplan-Meier method. Cox regression analysis was performed to determine the independent contribution of each prognostic factor. RESULTS: After 37 months of median follow-up (range, 12-106), overall survival (OS) was 71 % [95 % confidence interval (CI), 54-88], disease-free survival (DFS) 61 % [95 % CI, 44-78] and loco-regional control (LRC) 76 % [95 % CI, 62-90]. In univariate analyses the [(18)F]FDG-PET/CT parameters unfavorably influencing OS, DFS and LRC were pre-treatment TGV-cutoff ≥562 (37 vs. 76 %, p = 0.01; 33 vs. 70 %, p = 0.002; and 55 vs. 83 %, p = 0.005, respectively), mean pre-treatment tumor SUV cutoff ≥5 (57 vs. 86 %, p = 0.03; 36 vs. 88 %, p = 0.004; 65 vs. 88 %, p = 0.04, respectively) and a partial tumor metabolic response after treatment (9 vs. 29 %, p = 0.0008; 0 vs. 83 %, p < 0.0001; 22 vs. 96 %, p < 0.0001, respectively). After multivariate analyses a partial tumor metabolic response after treatment remained as an independent prognostic factor unfavorably influencing DFS and LRC (RR 1:7.7, p < 0.0001, and RR 1:22.6, p = 0.0003, respectively) while the pre-treatment TGV-cutoff ≥562 negatively influenced OS and DFS (RR 1:2, p = 0.03, and RR 1:2.75, p = 0.05). CONCLUSIONS: Parameters capturing the pre-treatment glycolytic volume and metabolic activity of [(18)F]FDG-positive disease provide important prognostic information in patients with CC treated with CRT. The post-therapy [(18)F]FDG-PET/CT uptake (partial tumor metabolic response) is predictive of disease outcome.