DWI和1H-MRS鉴别诊断结核性与细菌性脑脓肿

目的 探讨DWI、¹H-MRS鉴别诊断结核性脑脓肿与细菌性脑脓肿的价值。 方法 对7例结核性脑脓肿、20例细菌性脑脓肿患者,治疗前行常规MRI、DWI和¹H-MRS检查。DWI采用单次激发SE-EPI序列,扩散敏感系数(b值)为0及1000 s/mm²。¹H-MRS采用点分辨选择波谱(PRESS),扫描参数为TR 1000 ms、TE 144 ms。观察两类病变坏死区的常规MRI、DWI及¹H-MRS表现特点,分析其ADC值有无差异。采用ROC曲线评价DWI、¹H-MRS对结核性与细菌性脑脓肿的鉴别诊断价值。 结果 7例结核性脑脓肿共19个病灶,20例细菌性脑脓肿共23个病灶。结核性脑脓肿病灶坏死区DWI表现为低信号2个,等信号6个,高信号11个;23个细菌性脑脓肿病灶脓腔均呈明显高于脑白质的高信号。结核性和细菌性脑脓肿坏死区平均最小ADC值分别为(1.02±0.11)×10^-3mm²/s和(0.55±0.21)×10^-3mm²/s,差异有统计学意义(P<0.01)。¹H-MRS于7例结核性脑脓肿的8个病灶内坏死区均测到脂质(Lip)峰,未见氨基酸峰;20个细菌性脑脓肿有8个脓腔存在Lip或乳酸(Lac)峰,12个分布各异的多种氨基酸峰。ADC值、¹H-MRS鉴别诊断结核性脑脓肿与细菌性脑脓肿的ROC曲线下面积分别为0.94、0.80,敏感度分别为82.41%、100%,特异度分别为94.43%、60.00%。 结论 结合常规MRI,DWI及¹H-MRS对鉴别诊断结核性与细菌性脑脓肿有重要临床应用价值。

Differentiation of tuberculous from bacterial brain abscesses with DWI and in vivo proton MR spectroscopy

Objective To explore the value of DWI and in vivo proton MR spectroscopy (¹H-MRS) in the differentiation of tuberculous from bacterial brain abscesses. Methods Conventional MR imaging, DWI and ¹H-MRS were performed in 27 patients (7 with tuberculous brain abscesses and 20 with bacterial brain abscesses) before treatments. DWI was performed using a single shot SE-EPI pulse sequence with diffusion sensitivity of b=0 and 1000 s/mm². ¹H-MRS was performed using PRESS sequence (TR 1000 ms, TE 144 ms). The features of the core of these lesions on MRI, DWI and ¹H-MRS were analyzed. The mean ADC values from the core of these lesions were calculated. ROC curve analysis was done to evaluate the performance of DWI and ¹H-MRS in differentiating tuberculous from bacterial brain abscesses. Results There were 19 tuberculous brain abscesses and 23 bacterial brain abscesses. The necrotic areas of tuberculous brain abscesses were found on DWI, including hypointensity in 2, isointensity in 6, and hyperintensity in 11, and 23 bacterial brain abscesses appeared hyperintensity. There was significant difference on the mean minimum ADC value between tuberculous and bacterial brain abscesses ( ×10^-3 mm²/s and ×10^-3 mm²/s, P<0.01). Lipid (Lip) was seen in all the 8 tuberculous abscesses which underwent ¹H-MRS, with no evidence of amino acids. The bacterial brain abscesses showed Lip or Lactic acid (Lac) in 8 lesions and amino acids in 12 lesions of bacterial brain abscesses on ¹H-MRS. Area under the ROC curves of ADC value and ¹H-MRS was 0.94 and 0.80, respectively. Using ADC value and ¹H-MRS for differentiating tuberculous from bacterial brain abscesses, the sensitivity was 82.41%, 100%, and specificity was 94.43%, 60.00%, respectively. Conclusion DWI and ¹H-MRS combined with conventional MRI play an important role in differentiating tuberculous and bacterial brain abscesses.