扩散加权成像检测软组织感染脓腔

Diffusion-weighted imaging in detecting abscess formation on soft tissue infection

目的探讨DWI在检测软组织感染有无脓腔形成中的价值。方法收集14例经临床确诊的细菌性软组织感染伴脓腔形成病例,其中10例接受B超引导下抽吸排脓,2例接受手术切开排脓,1例接受病灶切除术经病理证实为软组织感染,1例病灶切除术后病理证实为腱鞘囊肿伴感染。使用1.5T MR行常规MR平扫、增强扫描及DWI。结果 14例共15个脓腔,其中13例为单发、1例为多发;多房脓腔3个,单房脓腔12个,11个脓腔呈稍长T1长T2信号,增强扫描均无强化,所有脓腔DWI均呈不同程度的高信号;ADC图显示12个脓腔的水分子弥散明显受限、2个不均匀受限、1个受限不明显。脓肿壁及分隔DWI均无法分辨、ADC图上8个尚可分辨、增强扫描均呈明显强化且显示清晰。周围炎性水肿均呈长T2信号,其范围于T2W FATSAT或STIR序列上最易分辨,于T1WI和DWI上最难分辨;增强扫描水肿区呈广泛连续的片状强化和(或)散在肌束样、线条状、斑片状不规则强化。结论 DWI可作为MR评价软组织感染是否形成脓腔的重要辅助序列,尤其对于磁共振对比剂禁忌者;常规MRI对显示感染范围、脓肿部位及其结构具有优势。

Objective To assess the value of DWI in detecting abscess cavity in patients with soft tissue infection.Methods Fourteen patients of soft tissue infection with abscesses were confirmed clinically.Ultrasound guided needle aspiration was performed in 10 cases,surgical incision and drainage were performed in 2 cases,surgical resection was performed in 1 case,1 patient of ganglion cyst with infection was diagnosed pathologically.All patients underwent plain,contrast enhanced scan and DWI with 1.5T MR.Results The total 15 abscesses cavities were found,including 13 cases of solitary abscess and 1 case of multiple abscesses.Three abscesses had multiple cavities and 12 abscesses had single cavity.Eleven abscesses cavities showed slight hypointensity on T1WI and hyperintensity on T2WI.All abscesses cavities showed non-enhancement and varying degrees of high signal on DWI,12 showed restricted diffusion,2 showed restricted diffusion unevenly and 1 showed restricted diffusion unconspicuous on ADC maps.All the walls and separations of abscesses were invisible on DWI,8 obviously enhanced and could be distinguish on ADC maps.The soft tissue inflammatory edema showed hyperintensity on T2WI,and the spectrums were observed easily on T2W fat-saturated or STIR,while difficultly on T1WI or DWI.The edema showed extensive,consecutive and schistose enhancement and/or dispersive girdle,linear,speckle,irregular enhancement.Conclusion DWI is a useful adjunctive sequence in the diagnosis of soft tissue infection,especially when gadolinium is contraindicated.But conventional MRI is irreplaceable on the spectrum of soft tissue infection,the location and construction of the abscess.