Rovaris Marco, Gallo Antonio, Valsasina Paola, Benedetti Beatrice, Caputo Domenico, Ghezzi Angelo, Montanari Enrico, Sormani Maria Pia, Bertolotto Antonio, Mancardi Gianluigi, Bergamaschi Roberto, Martinelli Vittorio, Comi Giancarlo, Filippi Massimo
Neuroimaging Research Unit, Scientific Institute and University Ospedale San Raffaele, Via Olgettina 60, 20132 Milan, Italy.
Neuroimage. 2005 Feb 15;24(4):1139-46. doi: 10.1016/j.neuroimage.2004.10.006. Epub 2004 Nov 26.
The mechanisms underlying the progressive course of multiple sclerosis (MS) are not fully understood yet. Since diffusion tensor (DT) MRI can provide quantitative estimates of both MRI-visible and MRI-occult brain damage related to MS, the present study investigated the value of DT MRI-derived measures for the assessment of the short-term accumulation of white and gray matter (GM) pathology in patients with primary progressive (PP) and secondary progressive (SP) MS. Fifty-four patients with PPMS and 22 with SPMS were studied at baseline and after a mean follow-up of 15 months. Dual-echo, T1-weighted, and DT MRI scans of the brain were acquired on both occasions. Total lesion volumes (TLV) and percentage brain volume changes (PBVC) were computed. Mean diffusivity (MD) and fractional anisotropy (FA) maps of the normal-appearing white (NAWM) and gray matter (NAGM) were produced, and histogram analysis was performed. In both patient groups, a significant increase of average lesion MD (P = 0.01) and of average NAGM MD (P = 0.007) was found at follow-up. No significant differences between PPMS and SPMS patient groups were found for the on-study changes of any MRI-derived measure. No significant correlations were found between the percentage changes of DT MRI-derived measures and those of TLV and PBVC. No significant changes of DT MRI-derived measures were observed in age-matched healthy controls over the same study period. Over a 1-year period of follow-up, DT MRI can detect tissue changes beyond the resolution of conventional MRI in the NAGM of patients with progressive MS. The accumulation of DT MRI-detectable gray matter damage does not seem to merely depend upon the concomitant increase of T2-visible lesion load and the reduction of brain volume. These observations suggest that progressive NAGM damage might yet be an additional factor leading to the accumulation of disability in progressive MS.
多发性硬化症（MS）病情进展的潜在机制尚未完全明确。由于扩散张量（DT）磁共振成像（MRI）能够对与MS相关的MRI可见及MRI隐匿性脑损伤进行定量评估，本研究探讨了DT MRI衍生指标在评估原发性进展型（PP）和继发性进展型（SP）MS患者白质和灰质（GM）病变短期累积情况方面的价值。对54例PPMS患者和22例SPMS患者在基线期及平均随访15个月后进行了研究。两次检查均获取了脑部的双回波、T1加权和DT MRI扫描图像。计算了总病变体积（TLV）和脑体积变化百分比（PBVC）。生成了正常外观白质（NAWM）和灰质（NAGM）的平均扩散率（MD）和分数各向异性（FA）图，并进行了直方图分析。在两个患者组中，随访时均发现平均病变MD（P = 0.01）和平均NAGM MD（P = 0.007）显著增加。对于任何MRI衍生指标的研究期内变化，PPMS和SPMS患者组之间未发现显著差异。DT MRI衍生指标的百分比变化与TLV和PBVC的百分比变化之间未发现显著相关性。在同一研究期间，年龄匹配的健康对照者的DT MRI衍生指标未观察到显著变化。在1年的随访期内，DT MRI能够检测到进展型MS患者NAGM中超出传统MRI分辨率的组织变化。DT MRI可检测到的灰质损伤累积似乎不仅仅取决于T2可见病变负荷的同时增加和脑体积的减小。这些观察结果表明，进展性NAGM损伤可能是导致进展型MS残疾累积的另一个因素。
