胸壁韧带样纤维瘤病的HRCT和MRI诊断价值

Diagnostic value of HRCT and MRI of desmoid fibromatosis in chest wall

目的:探讨韧带样纤维瘤病(DF)的高分辨率CT(HRCT)及MRI表现,提高HRCT及MRI诊断水平。方法:回顾性分析经手术病理证实的32例DF患者的临床、HRCT及MRI表现。32例均行CT平扫和增强扫描,15例行MRI平扫,其中7例行动态增强扫描。主要观察指标包括肿瘤的形态学特征(大小、形态、位置、密度、强化特征、MR信号、邻近肋骨改变、胶原纤维征)及表观扩散系数(ADC)值。结果:肿瘤直径2.1~12.3 cm,平均(6.4±1.8)cm;肿瘤呈类圆形或类椭圆形18例(56%),不规则形14例(44%);浅表型9例(28%),深部型23例(72%)。在HRCT平扫上呈等密度6例,等~低密度24例;肿瘤内密度欠均匀23例(72%),密度均匀9例(28%);在HRCT增强扫描动脉期图像上病灶均呈轻度强化,静脉期及延迟期呈中度或明显不均匀强化,其中17例病灶内条片状稍低密度影在延迟图像上呈轻度强化。肿瘤实质在T_(2)WI及STIR序列上呈高信号10例,不均匀偏高信号5例,在T_(1)WI上呈等或稍低信号,15例(100%)瘤体内含有“草根状”或索条状胶原纤维,其在T_(1)WI上呈等或稍低信号,T_(2)WI和STIR图像上呈低信号;7例在增强图像上呈明显不均匀强化,其内条索状胶原纤维未见强化。肿瘤实性成分的平均ADC值为(1.27×10^(-3)±0.21×10^(-3))mm^(2)/s。在HRCT骨窗图像上观察,病灶邻近骨质呈针状或拉丝样骨质增生13例(41%),侵袭性骨质破坏并骨质增生硬化10例(31%),病变包绕肋骨、局部肋骨受侵呈骨质密度减低表现1例(3%)。结论:DF的HRCT及MRI表现具有一定的特征性,针状或拉丝样骨质增生、侵袭性骨质破坏并骨质增生硬化、以及病灶内有"草根状"或索条状胶原纤维是其特征性表现,HRCT及MRI对DF的鉴别诊断及术前评估具有重要价值。

Objective:To explore the high-resolution CT(HRCT)and MRI features of desmoid fibromatosis(DF)located at chest wall,thus to improve the diagnostic level of HRCT and MRI for this disease.Methods:The clinical,HRCT and MR imaging characteristics of 32 cases with chest wall DF confirmed by surgery and pathology were retrospectively analyzed.32 cases underwent both CT plain scan and enhanced scan,15 cases underwent MRI plain scan,of which 7 cases underwent dynamic enhanced scan.The main analysis indexes included morphological characteristics(tumor size,shape,location,density,enhancement patterns,MR signal,adjacent rib changes,collagen fiber signs)and appa-rent diffusion coefficient(ADC).Results:The tumor size was 2.1~12.3cm,with an average of(6.4±1.8)cm;18 cases(56%)were round or oval-like tumors,14 cases were irregular(44%);9 cases were superficial type(28%),and 23 cases(72%)were deep type.On plain HRCT images,6 cases were isodensity,24 cases were hypo-density;23 cases(72%)showed uneven density,and 9 cases(28%)showed uniform density.On arterial phase of enhanced scan,the tumors showed mild enhancement;and in venous phase and delayed phase,the tumors showed moderate to obvious ununiform enhancement.Among them,17 cases of the lesions showed mild enhancement on delayed scan with slightly low-density shadow.Tumor parenchyma showed high signal on T_(2)WI and STIR sequence in 10 cases,uneven high signal in 5 cases,equal or slightly low signal on T_(1)WI;7 cases showed obvious uneven enhancement on enhanced scan,and the internal cord-like collagen fiber showed no enhancement.15 tumors(100%)contained"grass-root"or cord-like collagen fiber,which showed equal or slightly low signal on T_(1)WI,and low signal on T_(2)WI STIR.The average ADC value of the solid component was(1.27×10^(-3)±0.21×10^(-3))mm^(2)/s.On the HRCT images with bone window,the adjacent bone of 13 cases(41%)of the tumor showed needle-like or brushed bone hyperplasia;aggressive bone destruction and bone hyperplasia and sclerosis in 10 cases(31%).The ribs were surrounded by lesions with local rib invasion and decreased bone density in one case(3%).Conclusion:The HRCT and MRI manifestations of desmoid fibromatosis have certain characteristics;needle-like or brush-like bone hyperplasia,aggressive bone destruction and bone hyperplasia and sclerosis,"grass-rooted"or cord-like collagen fibers are characteristic changes.HRCT and MRI have important value in the differential diagnosis and preoperative evaluation.