Three dimensional pseudo-continuous arterial spin labeling imaging in clinical staging of nasopharyngeal carcinoma

Abstract

Objective To investigate the application value of three dimensional pCASL (3D pseudo-continuous arterial spin labeling) with three groups of post-labeling delay (PLD) time in the clinical staging of nasopharyngeal carcinoma. Methods Thirty-one patients with nasopharyngeal carcinoma diagnosed by pathology between August 2016 and January 2018 were analyzed. All patients underwent nasopharyngeal MRI routine plain scan, 3D pCASL and dynamic enhanced scan, 3D pCASL scan in three groups, PLD time was set to 1 525 ms, 2 025 ms and 2 525 ms respectively. The clinical stages (8th Edition UICC/AJCC staging) of patients, the overall clinical stage, T stage and N stage were divided into high and low stage group low stage group: 7 cases of overall stage Ⅰ+Ⅱ, 12 cases of T stage T1+T2, 10 cases of N stage N0+N1, high stage groups: 24 cases of overall stage Ⅲ+Ⅳ, 19 cases of T stage T3+T4, 21 case of N stage N2+N3. The GE AW4.6 workstation is used to process the 3D pCASL data. With reference to the axial T2WI image, irregular ROIs with complete inclusion of tumor were manually drawn to automatically generate the mean blood flow to the Tumor Blood Flow (TBF). In three subgroups, PLD time measurement of TBF values were recorded as the TBF (1.5), the TBF (2.0) and TBF (2.5)which were shown in the TBF color charts. Derived variables were used to assess the TBF values of three groups. Two independent sample t test was used to compare TBF values between high and low stages of nasopharyngeal carcinoma. Spearman correlation analysis was used to analyze the TBF value of nasopharyngeal carcinoma and the each clinical stage. ROC analysis was performed to calculate its diagnostic efficiency. Results On the TBF color map, TBF and perfusion was slightly higher for nasopharyngeal carcinoma. The TBF value of nasopharyngeal carcinoma in three groups at PLD time was TBF(1.5)=(140.59+46.51) ml·100 g-1·min-1, TBF(2.0)=(149.93+48.63) ml·100 g-1·min-1, and TBF(2.5)=(157.76+44.83) ml·100 g-1·min-1. In the overall clinical stage, T stage and N stage, the TBF value of the high stage group was significantly higher than that of the low stage group(Total clinical stage: t=2.471,2.774 and 2.6,respectively;T stage: t=1.581,1.348 and 1.472,respectively; N stage: t=2.083,2.129 and 2.046,respectively; all P<0.05). TBF value was positively correlated with overall stage, T stage and N stage (when PLD=1.5 s, r=0.474,0.289 and 0.447,respectively;When PLD=2.0 s,r=0.509,0.311 and 0.471,respectively; When PLD=2.5 s,r=0.500, 0.252 and 0.463, respectively; all P<0.05). According to ROC curve analysis, TBF has good diagnostic performance in all clinical stage. Conclusions 3D pCASL, as a non-invasive magnetic resonance perfusion imaging technique, can accurately measure the TBF value of nasopharyngeal carcinoma. The TBF value obtained by PLD=2.0 s had the best correlation with each stage, which has a guiding value for the clinical staging of nasopharyngeal carcinoma. Key words: Nasopharyngeal neoplasms; Neoplasm staging; Diagnostic techniques and procedures; Magnetic resonance imaging