Marzi Simona, Forina Chiara, Marucci Laura, Giovinazzo Giuseppe, Giordano Carolina, Piludu Francesca, Landoni Valeria, Spriano Giuseppe, Vidiri Antonello
Medical Physics Laboratory, Regina Elena National Cancer Institute, Rome, Italy.
J Magn Reson Imaging. 2015 Apr;41(4):974-82. doi: 10.1002/jmri.24626. Epub 2014 Apr 3.
To investigate the potential of intravoxel incoherent motion (IVIM) MRI for early evaluation of irradiated major salivary glands.
Thirty-four patients with head-neck cancer were included in a prospective study. All patients underwent three serial IVIM-MRI: before, half-way through, and at the end of radiotherapy (RT). Apparent diffusion coefficient (ADC), ADClow derived in the low b-value range, perfusion fraction f, and pure diffusion coefficient D were estimated. Pretreatment values and early changes of diffusion parameters were correlated with parotid mean dose (Dmean ) and volume reduction after RT.
Changes in diffusion parameters over time were all significant (P < 0.001 for ADC, ADClow , and D, P = 0.003 for f). Variations of ADC, ADClow , and f were not correlated with Dmean (P = 0.089, P = 0.252 and P = 0.884, respectively), whereas a significant relationship was found between changes in D and Dmean (r = 0.197 with CI95% = 0.004-0.375, P = 0.046). Pretreatment f and Dmean were the best independent predictors for the percentage shrinkage (P = 0.0003 and 0.0597 respectively; R(2) = 0.391).
Early changes of irradiated major salivary glands can be noninvasively evaluated by IVIM-MRI. Perfusion-related coefficients in conjunction with dosimetric information increase our capability to predict the change in parotid volume and hence, if further validated, guide treatment strategy in RT.
探讨体素内不相干运动（IVIM）磁共振成像（MRI）对放射性大唾液腺早期评估的潜力。
34例头颈癌患者纳入一项前瞻性研究。所有患者在放疗（RT）前、放疗中期和放疗结束时接受了三次连续的IVIM-MRI检查。估计表观扩散系数（ADC）、低b值范围内得出的ADClow、灌注分数f和纯扩散系数D。将治疗前扩散参数值及早期变化与腮腺平均剂量（Dmean）和放疗后体积缩小情况进行关联分析。
扩散参数随时间的变化均具有显著性（ADC、ADClow和D的P<0.001，f的P = 0.003）。ADC、ADClow和f的变化与Dmean无相关性（分别为P = 0.089、P = 0.252和P = 0.884），而D的变化与Dmean之间存在显著关系（r = 0.197，95%CI = 0.004 - 0.375，P = 0.046）。治疗前的f和Dmean是体积缩小百分比的最佳独立预测指标（分别为P = 0.0003和0.0597；R(2)=0.391）。
IVIM-MRI可对放射性大唾液腺的早期变化进行无创评估。灌注相关系数结合剂量学信息提高了我们预测腮腺体积变化的能力，因此，如果进一步得到验证，可指导放疗的治疗策略。
