CT增强鉴别诊断腹内型韧带样纤维瘤病与胃肠道间质瘤的价值

The role of CT enhancement in differentiation of intra-abdominal desmoid-type fibromatosis from gastric-intestinal stromal tumor

目的评价CT增强对腹内型韧带样纤维瘤病(IAF)与胃肠道间质瘤(GIST)的鉴别诊断价值。方法收集病理证实的IAF患者23例(IAF组)和GIST患者37例(GIST组)的资料,均行CT平扫和CT增强检查,定性分析比较两组形态学表现,定量分析病灶长径、短径、平扫及增强各期CT值。图像由两名工作经验5年以上的影像科医师独立分析与测量。对于测量有统计学意义的定量参数,进行受试者操作特性(ROC)曲线分析,确定诊断阈值。结果与GIST组相比,IAF组CT表现多为卵圆形或不规则形软组织肿块,多位于腹腔胃肠壁外,内部坏死少见,均匀强化(P=0.001,P=0.005,P=0.003,P=0.001);而病灶边界、瘤内血管在两组间的差异无统计学意义(P=0.867,P=0.11)。IAF组与GIST组最大界面长径、短径和平扫CT值差异无统计学意义(6.0±1.9)cm vs(5.8±1.8)cm,(5.5±1.5)cm vs(5.7±1.6)cm,(31±2)HU vs(30±3)HU,P=0.717,P=0.616,P=0.186);两组动脉期、静脉期CT值、动脉期绝对强化值及静脉期绝对强化值均小于GIST组(36±7)HU vs(35±10)HU,(45±8)HU vs(62±10)HU,(6±6)HU vs(23±10)HU,(15±8)HU vs(31±11)HU,P=0.001,P=0.001,P=0.001,P=0.001)。以动脉期CT值小于47HU,静脉期CT值小于56HU为鉴别诊断的阈值,诊断IAF的敏感度分别是87.0%、91.3%,特异度分别是89.2%、78.4%。结论与GIST相比较,IAF多位于腹腔胃肠壁外、形态表现为卵圆形或不规则形、病灶内部少坏死,均匀强化,动脉强期CT值多低于47HU,门静脉期多低于45HU,这6个特征对鉴别IAF与GIST有重要价值。

Objective To evaluate the value of enhanced CT in differentiating intra-abdominal desmoid-type fibromatosis(IAF)from gastric-intestinal stromal tumor(GIST).Methods Twenty-three cases with IAF and thirty-seven cases with GIST were enrolled.All patients underwent plain and enhancement CT scan.The morphological manifestations were qualitatively evaluated.The lesions,long-diameter,short-diameter,plain scan and enhanced CT value of each phase were quantitatively evaluated.The images were analyzed and measured independently by two radiologists with more than 5 years'experience.For statistically significant item parameters,the receiver operating characteristic(ROC)curve was analyzed to determine the diagnostic threshold.Results Compared with GIST group,IAF group usually showed oval or irregular,mostly located outside the gastrointestinal wall,rare necrosis and homogeneous enhancement(P=0.001,P=0.005,P=0.003,P=0.001).There was no significant difference between the two groups in lesion boundary and blood vessels(P=0.867,P=0.11).There were no significant differences between IAF group and GIST group in the length diameter,short diameter and plain CT value between IAF group and GIST group(6.0±1.9)cm vs(5.8±1.8)cm,(5.5±1.5)cm vs(5.7±1.6)cm,(31±2)HU vs(30±3)HU,P=0.717,P=0.616,P=0.186).There were significant differences between IAF group and GIST group in the venous CT value,the absolute enhancement value in arterial phase and in venous phase between IAF group and GIST group(36±7)HU vs(35±10)HU,(45±8)HU vs(62±10)HU,(6±6)HU vs(23±10)HU,(15±8)HU vs(31±11)HU,P=0.001,P=0.001,P=0.001,P=0.001).The sensitivity of IAF was 87.0%and 91.3%,when the value of CT in arterial phase was less than 47 HU.The specificity was 89.2%and 78.4%,when the value of CT in venous phase was less than 56 HU.Conclusion Compared with GIST,IAF is mostly located outside the gastrointestinal wall,showing oval or irregular shape,less necrosis and homo-geneous enhancement.The value of CT in arterial phase is lower than 47 HU,and that in portal phase is lower than 45 HU.These six features are of great value in differentiating IAF from GIST.