3．0T磁共振成像在动态观察肺部肿瘤氩氦刀术后变化中的价值

Using 3. 0 T MR to dynamically observe ablated lung tumors after percutaneous cryotherapy therapy

目的初步探讨肺部恶性肿瘤氩氦刀术后多个时间点消融区磁共振成像（MRI）表现及变化趋势，提高对消融区MRI影像学特点及其变化的认识。方法2014年7月至2016年1月在河南省肿瘤医院住院并接受氩氦刀治疗共23例（26个病灶）的肺部恶性肿瘤患者纳入本研究。所有患者分别于治疗前、术后1d，1周，1、3、6和12个月进行胸部MR平扫和动态增强扫描，两名阅片者独立双盲法对图像进行分析，采用5分制评价消融区T1WI和T2W1上信号强度，并采用Kappa检验比较结果的一致性。测量消融区最大径，并分析消融区最大径和信号强度随时间的变化趋势。同时绘制消融区动态增强时间一信号曲线并分类。结果术后1d，26个消融区呈高低混杂信号；术后1周表现为T1WI高（22／26，84．6％）、T2WI高信号（17／26，65．4％）并边缘低信号环（22／26，84．6％）；术后1个月17个（65．4％）为T1WI高信号，两名阅片者分别评价22（84．6％）和21（80．8％）为T2WI高信号；术后3个月，大多呈T1WI（18／26，69．2％）及T2WI（19／26，73．1％）等信号，19个消融区（73．1％）呈楔形影；术后6和12个月，消融区大小和信号强度变化不大。术后1d消融区最大径最大并逐渐缩小，信号强度术后1周最大并逐渐下降至等信号。术后1d至1个月消融区时间．信号曲线为无明确强化的直线型，术后3～12个月呈轻度延迟强化的流人型。随访周期内22个病灶（84．6％）未见复发，4例复发病灶均发生在术后3个月，且术后1周消融区边缘低信号环不完整。结论肺部肿瘤氩氦刀术后MRI表现具有一定的特征性，术后1周消融区边缘低信号环是否完整有助于判断复发，术后1周至3个月是观察消融区发生较大改变的重要时间窗，MRI在识别消融区及动态反映其变化方面具有重要价值。

Objective To initially explore MRI features and its changing trends including of lung tumors after Argon-Helium cryoablation therapy, and enhance the recognition of MR findings of lung tumors postcryoablation. Methods Twenty-three cases of patients with twenty six nodules of pulmonary malignance who received Argon-Helium cryoablation therapy in Henan Cancer Hospital from July 2014 to January 2016 were enrolled. All patients underwent unenhanced and dynamic contrast-enhanced MRI scans at pre-and 1- day,l-week, 1-, 3-, 6-, 12-month postcryoablation. Two radiologists independently reviewed MRI images, signal intensity in the ablated zone on T1WI and T2WI were assessed by a 5-point scale. The changing trends of size and signal intensity with time were showed by time-maximum diameter and time-score curve. Timesignal intensity curves based on dynamic enhanced sequence were also performed. Results Typical MRI findings includes：heterogeneous signal intensity on both T1WI and T2WI at 1-day postcryoablation （26/26, 100% ）. Hyper-intense on T1 WI（22/26, 84. 6% ） and T2WI（ 17/26, 65.4% ） with a hypo-intense rim at 1 -week postcryoablation. Decreasing signal intensity on T1WI（ 17/26,65.4% ） and increasing signal intensity on T2 WI （22/26,84. 6% ） at 1-month. Signal intensity declined to the level of muscle on both T1WI （ 18/26, 69.2% ） and T2WI（ 19/26,73.1% ） at 3-month, nineteen ablated zone turned into patchy shape（ 19/26,73.1% ）. The maximum diameter was largest at 1-day and gradually shrunk with time. The mean score value toped at 1-week and gradually decreased. A straight line type without definite enhancement was found from 1-day to 1-month postcryoablation, an inflow curve with a mild delayed enhancement was seen from 3- to 12- month. Totally 4 recurrence （4/26, 15.4% ） all occurred at 3-month and were lack of a complete hypo- intense rim at 1-week postcryoablation. Conclusion MRI findings of lung tumors posteryoablation are characteristic, a complete hypo-intense rim at 1-week is helpful to determine further recurrence, 1-week to 3-month is an important period to observe significant change of the ablation zone, MRI is valuable in identifying the ablation zone and can reflect its evolution with time.