计算机断层扫描和磁共振成像对胰腺神经内分泌肿瘤的术前诊断

Preoperative diagnosis of pancreatic neuroendocrine neoplasms with computed tomography and magnetic resonance imaging

目的评价CT和MRI在胰腺神经内分泌肿瘤（PNEN）诊断中的价值，探讨影响PNEN术前影像诊断的因素。方法收集2016年1月至11月行手术治疗或活组织检查的PNEN病例，分析PNEN患者的CT和MRI影像资料，并测量病灶和周围胰腺组织的CT值或信号强度值，计算病灶对比噪声比（CNR）。比较CT与MRI的定位敏感度和定性准确率，以及MRI不同序列定位诊断敏感度。对比分析无功能性肿瘤和功能性肿瘤的定性诊断准确率，以及增强CT动脉期与门静脉期病灶CNR。敏感度、准确率、构成比的比较采用非参数分析，定量指标比较采用独立样本t检验和单因素方差分析。结果共选取54例PNEN患者，其中2例分别有2个病灶，共56个病灶。有44例（46个病灶）同时进行了CT和MRI检查，CT定位诊断敏感度为97．8％（45／46），定性诊断准确率为87．0％（40／46）；MRI定位诊断敏感度为97．8％（45／46），定性诊断准确率为89．1％（41／46）。CT与MRI病灶定位诊断敏感度和定性诊断准确率差异均无统计学意义（P均〉0．05）。CT动脉期病灶CNR大于门静脉期（4．7±3．8比3．4±2．5），差异有统计学意义（t=2．949，P〈0．05）。MRIT1加权成像脂肪抑制（T1wI-FS）序列病灶检出率为90．0％（45／50），MRIT2加权成像脂肪抑制（T2WI-FS）序列病灶检出率为88．0％（44／50），扩散加权成像病灶检出率为86．0％（43／50），动态增强TIWI-FS病灶检出率为91．7％（44／48），以上MRI各序列检测效能比较差异无统计学意义（Q=2．526，P=0．510）。无功能性肿瘤最大径大于功能性肿瘤[（2．9±1．6）cm比（1．7±0．7）cm]，差异有统计学意义（t=3．479，P〈0．05）。无功能性肿瘤术前CT和MRI总体确诊率（至少有1项检查确诊）为70．8％（17／24），低于功能性肿瘤的100．0％（31／31），差异有统计学意义（χ2=10．360，P=0．002）。结论CT和MRI在PNEN定位检测中均具有较高的敏感性，并可互相补充；CT动脉期病灶显示较门静脉期更明显，MRI各序列可互相补充。CT和MRI在PNEN术前定性诊断中的作用相当，无功能性PNEN的CT和（或）MRI表现不典型，诊断较功能性肿瘤困难。

Objective To assess the value of computed tomography （CT） and magnetic resonance imaging （MRI） in the diagnosis of pancreatic neuroendocrine neoplasms （PNEN） and to analyze the factors influencing the preoperative imaging diagnosis of PNEN. Methods From January 2016 to November 2016, patients with PNEN diagnosed by surgery and biopsy were collected. CT and MRI data of them were analyzed. The CT values or signal intensity of the lesions and the pancreatic parenchyma were measured and the contrast-to- noise ratio （CNR） of the lesion was calculated. Detecting sensitivity and diagnosis accuracy of CT and MRI were compared. Detecting sensitivity of different MRI sequences was also analyzed. Diagnosis accuracy of non- functional PNEN and functional PNEN was compared and analyzed. Lesion CNR was compared between arterial phase and portal venous phase of the contrast enhanced CT. The sensitivity, accuracy and constituent ratio werecompared by nonparametric analysis. Independent sample t test and one-way analysis of variance were performed for the quantitative parameters comparison. Results A total of 54 patients with 56 lesions of PNEN were included for two of whom had two lesions each. CT and MRI were both performed in 44 patients （46 lesions）. Detecting sensitivity and diagnosis accuracy of CT were 97.8%（45/46） and 87.0% （40/46）, respectively. Detecting sensitivity of MRI were 97.8% （45/46） and 89.1% （41/46）, respectively. There was no significant difference in detecting sensitivity and diagnosis accuracy between CT and MRI （both P〉0.05 ）. The CNR of lesion in arterial phase was higher than that of portal venous phase（4.7±3.8 vs 3.4 ±2.5）, and the difference was statistically significant （t=2. 949, P〈0.05）. Detecting rates of T1 weighted imaging with fat suppression （T1WI-FS） image, T2 weighted imaging with fat suppression （T2WI-FS） image, diffusion weighted imaging and dynamic contrast enhanced TlWI-FS image were 90.0%（45/50）, 88.0% （44/50）, 86.0% （43/50）, and 91.7% （44/48）, respectively. There was no significant difference in detecting rate among these images sequences （Q=2. 526, P=0. 510）. Tumor diameter in non-functional PNEN was significantly larger than that in functional PNEN （（2.9±1.6） cm vs （1.7±0.7） cm） （t=3. 479,P〈0.05）. The overall diagnosis rate of non-functional PNEN with CT and MRI before operation was 70.8% （17/24）, which was significantly lower than that of functional PNEN （100.0 %, 31 / 31 ） （χ2 = 10.360, P= 0.002）. Conclusions CT and MRI are both sensitive in detecting PNEN, and they were two complementary modalities. CT image in arterial phase delineated the lesion better than that in portal venous phase. MRI images with different sequences can be complementary and there is no significant difference in detecting sensitivity for PNEN among different sequences. CT and MRI play an equal role in the diagnosis of PNEN before operation. Because of atypical CT and MRI findings, the diagnosis of non-functional PNEN is more difficult than functional PNEN.