Koç Murat, Kaya Gamze Ç, Demir Yusuf, Sürücü Erdem, Sarioğlu Sülen, Obuz Funda, Öztop İlhan, Görken İlknur B, Sökmen Selman
aDepartment of Nuclear Medicine, Atatürk Government Hospital, Aydin bDepartment of Nuclear Medicine, School of Medicine, Yüzüncü Yil University, Van Departments of cNuclear Medicine dPathology eRadiology fMedical Oncology gRadiation Oncology hGeneral Surgery, School of Medicine, Dokuz Eylül University, Izmir, Turkey.
Nucl Med Commun. 2015 Sep;36(9):898-907. doi: 10.1097/MNM.0000000000000342.
We aimed to investigate the value of PET-CT in therapy response and the correlation of quantitative PET parameters with histopathologic results in patients with locally advanced rectal cancer (LARC) before and after neoadjuvant chemoradiotherapy. We also analyzed the correlation of PET-CT parameters between Ki-67 and glucose transporter 1 (GLUT1).
A total of 29 patients diagnosed with LARC who had undergone a biopsy between 2009 and 2012 were included in our study. Quantitative PET parameters [standardized uptake value (SUV)max-mean, lean body mass SUV(max-mean), tumor/liver SUV, retention index , and [INCREMENT]SUV(max)] were measured before and after therapy using PET-CT. Tumor regression grade (TRG) was evaluated according to Wheeler's classification. Patients in grade 1 were considered responders, whereas patients at grades 2 and 3 were considered nonresponders. Immunohistochemical staining with Ki-67 and GLUT1 was performed on biopsy and surgical specimens. The correlation between staining ratios and SUV was also investigated.
SUV parameters were significantly decreased after therapy (P < 0.001). Twelve (41%) patients were at TRG1, 10 (35%) were at TRG2, and seven (24%) were at TRG3. A cutoff SUV(max) of 5.05 to discriminate between responders and nonresponders after treatment revealed a sensitivity of 57%, specificity of 73%, negative predictive value of 65%, positive predictive value of 67%, and accuracy of 66%. Using a cutoff of 3.55 for the SUV(mean) (standardized measurement of SUV with 1.2-cm-diameter region of interest) revealed a sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of 67, 76, 67, 76, and 72%, respectively. For a cutoff of 1.95 for the tumor SUV(mean)/liver SUV(mean), these diagnostic values after therapy were 73, 78, 82, 67, and 76%, respectively. We found a moderate correlation between liver-based SUV(max) (r = -0.35, P = 0.019) and SUV(mean )(r = -0.31, P = 0.036) with GLUT1 after therapy. Quantitative PET parameters and retention index were moderately correlated with Ki-67.
PET-CT is a useful method for assessing the response to neoadjuvant chemoradiotherapy in patients with LARC. The most significant parameter for assessing treatment response using SUV parameters is the tumor/liver ratio.
我们旨在研究正电子发射断层显像-计算机断层扫描（PET-CT）在局部晚期直肠癌（LARC）患者新辅助放化疗前后治疗反应评估中的价值，以及PET定量参数与组织病理学结果的相关性。我们还分析了PET-CT参数与Ki-67和葡萄糖转运蛋白1（GLUT1）之间的相关性。
本研究纳入了2009年至2012年间共29例经活检确诊为LARC的患者。使用PET-CT在治疗前后测量定量PET参数[最大标准化摄取值（SUV）均值、去脂体重SUV（最大均值）、肿瘤/肝脏SUV、滞留指数以及SUV增加值（ΔSUV）]。根据惠勒分类法评估肿瘤退缩分级（TRG）。1级患者被视为反应者，而2级和3级患者被视为无反应者。对活检和手术标本进行Ki-67和GLUT1免疫组织化学染色。还研究了染色率与SUV之间的相关性。
治疗后SUV参数显著降低（P<0.001）。12例（41%）患者为TRG1级，10例（35%）为TRG2级，7例（24%）为TRG3级。治疗后区分反应者和无反应者的SUV最大值临界值为5.05，其敏感性为57%，特异性为73%，阴性预测值为65%，阳性预测值为67%，准确性为66%。SUV均值（使用直径1.2 cm感兴趣区对SUV进行标准化测量）临界值为3.55时，其敏感性、特异性、阴性预测值、阳性预测值和准确性分别为67%、76%、67%、76%和72%。肿瘤SUV均值/肝脏SUV均值临界值为1.95时，治疗后的这些诊断值分别为73%、78%、82%、67%和76%。我们发现治疗后基于肝脏的SUV最大值（r = -0.35，P = 0.019）和SUV均值（r = -0.31，P = 0.036）与GLUT1之间存在中度相关性。定量PET参数和滞留指数与Ki-67中度相关。
PET-CT是评估LARC患者新辅助放化疗反应的有用方法。使用SUV参数评估治疗反应的最显著参数是肿瘤/肝脏比值。
