MRI和能谱CT成像在胰岛素瘤诊断中的初步研究

Comparative Study of MRI Imaging and Spectral CT Imaging in the Diagnosis of Insulinoma

目的 探讨和分析比较MRI和CT能谱成像在胰岛素瘤诊断中的应用价值。方法回顾性分析2008年1月至2011年4月行MRI扫描并经手术病理证实的43例胰岛素瘤患者的病例资料，其中15例同时行能谱CT扫描。分析表观扩散系数（ADC）值与能谱CT参数的相关性，比较MRI与能谱CT诊断胰岛素瘤的检出率。结果43例经手术病理证实胰岛索瘤，T_1WI＋抑脂（FS）、T_2WI＋Fs、扰相GRET。WI同反相位、DWI、3DLAVA多期动态增强各序列检出率分别为81％（35／43）、84％（36／43）、79％（34／43）、72％（31／43）、84％（26／31）。胰岛素瘤的ADC值低于周围正常胰腺的ADC值（P〈0．001）；同时进行MRI和能谱CT扫描的15例中，胰岛素瘤的ADC值与能谱CT各参数（40～140keV，碘-水）不具有相关性（P〉0．05）；MRI、能谱CT二者联合诊断检出率高于二者单独检出率。结论在胰岛素瘤的诊断中，MRI抑脂序列胰岛素瘤检出率较高；最佳单能量图像优于其他单能量图像，能谱参数联合诊断胰岛素瘤检出率优于各单能量参数。MRI和能谱CT检测胰岛素瘤的检出率相当，二者联合诊断有助于提高胰岛素瘤检出率。

Objective To explore the value of MR Imaging and dual energy spectral CT imaging in preoperative diagnosis of insulinomas. Methods Clinical information and image data of 43 cases with insnlinoma （ between Jan. 2008 and Mar. 2011 ） confirmed by surgery and histopathological examination were analyzed retrospectively, MRI scans were performed in the 43 patients and 15 cases of them underwent the dual phase DEsCT imaging. The insulinoma detection rate was calculated by MR imaging. The apparent diffusion coefficient （ADC） values of the insulinomas and that of surrounding normal pancreatic parenchyma in patients were calculated and compared. The correlation of ACD values and DEsCT was analyzed. The ability of MR imaging and dual energy spectral CT imaging to detect insulinomas was compared. Results The detection rate of T1WI ＋ fs,T2WI ＋ fs,out phase and in phase, DWI, dynamic enhanced 3D LAVA was respectively 81% （ 35/43 ）, 84% （ 36/43 ）, 79% （34/43）, 72% （ 31/43 ）, 84% （26/31 ）. The ADC values of insulinomas were lower compared with those of surrounding normal pancreatic parenchyma （P 〈 0. 001 ）. The differences of signals between insulinomas and surrounding normal pancreatic parenehyma on sequences with fat surppression were significant. In 15 cases both DEsCT and MRI, the correlation of ACD values and DEsCT was not statistically significant. The detection rate of combination both DEsCT and MRI was higher than either of them indenpendently. Canclusion MRI sequences with fat suppress improve the diagnostic sensitivity of insulinoma. The combination of monochromatic image and iodine density image can improve the diagnostic sensitivity of insulinomas. The optimal CNR monochromatic imaging has higher sensitivity in diagnosis of insulinomas than other monochromatic imaging.