Prediction of the response to docetaxel-based chemotherapy for locoregionally advanced nasopharyngeal carcinoma: the role of double-phase ^99mTc-MIBI SPECT/CT

To evaluate the role of double-phase ^99mTechnetium labeled sestamibi (^99mTc-MIBI) single-photon emission computed tomography/compute tomography (SPECT/CT) in predicting the response to neoadjuvant chemotherapy with docetaxel-based regimen in patients with nasopharyngeal carcinoma. Thirty-nine pathologically proven nasopharyngeal carcinoma patients participated in this prospective study. Before treatment, early and delayed SPECT/CT images were obtained 5 min and 2 h after an intravenous injection of 25–30 mCi ^99mTc-MIBI. All patients received neoadjuvant chemotherapy consisting of docetaxel, cisplatin plus 5-fluorouracil for two cycles. The relationships between the efficacy of neoadjuvant chemotherapy and early uptake ratio (EUR), delayed uptake ratio (DUR) and washout rate (WR) of ^99mTc-MIBI were evaluated. The EUR of ^99mTc-MIBI (2.8 ± 0.97) in the lesions which were sensitive to chemotherapy was significantly higher (p < 0.001) compared with that (1.69 ± 0.46) in the insensitive lesions. The difference of the DUR between the sensitive (1.65 ± 0.58) and the insensitive (1.06 ± 0.62) was also statistically significant (p = 0.011). However, the WR of ^99mTc-MIBI was not significantly different between the two groups. When a EUR of 1.97 and a DUR of 1.06 were used as the cutoff value, the sensitivity, specificity, positive and negative predictive values were 76.1, 87.5, 97.2 and 38.8 % for EUR, 91.3, 67.5, 90 and 66.6 % for DUR, respectively. These results suggest that the early and delayed uptake ratios of ^99mTc-MIBI calculated with SPECT/CT may have predictive value for identifying the response to neoadjuvant chemotherapy with docetaxel-based regimen in NPC patients.