Duan Y, Hildenbrand P G, Sampat M P, Tate D F, Csapo I, Moraal B, Bakshi R, Barkhof F, Meier D S, Guttmann C R G
Center for Neurological Imaging, Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
AJNR Am J Neuroradiol. 2008 Feb;29(2):340-6. doi: 10.3174/ajnr.A0795.
Lesion volume change (LVC) assessment is essential in monitoring MS progression. LVC is usually measured by independently segmenting serial MR imaging examinations. Subtraction imaging has been proposed for improved visualization and characterization of lesion change. We compare segmentation of subtraction images (SSEG) with serial single time-point conventional segmentation (CSEG) by assessing the LVC relationship to brain atrophy and disease duration, as well as scan-rescan reproducibility and annual rates of lesion accrual.
Pairs of scans were acquired 1.5 to 4.7 years apart in 21 patients with multiple sclerosis (MS). Scan-rescan MR images were acquired within 30 minutes in 10 patients with MS. LVC was measured with CSEG and SSEG after coregistration and normalization. Coefficient of variation (COV) and Bland-Altman analyses estimated method reproducibility. Spearman rank correlations probed associations between LVC and other measures.
Atrophy rate and net LVC were associated for SSEG (R = -0.446; P < .05) but not when using CSEG (R = -0.180; P = .421). Disease duration did not show an association with net lesion volume change per year measured by CSEG (R = -0.360; P = .11) but showed an inverse correlation with SSEG-derived measurements (R = -0.508; P < .05). Scan-rescan COV was lower for SSEG (0.98% +/- 1.55%) than for CSEG (8.64% +/- 9.91%).
SSEG unveiled a relationship between T2 LVC and concomitant brain atrophy and demonstrated significantly higher measurement reproducibility. SSEG, a promising tool providing detailed analysis of subtle alterations in lesion size and intensity, may provide critical outcome measures for clinical trials of novel treatments, and may provide further insight into progression patterns in MS.
病变体积变化（LVC）评估对于监测多发性硬化症（MS）的病情进展至关重要。LVC通常通过对连续的磁共振成像（MR）检查进行独立分割来测量。减法成像已被提出用于改善病变变化的可视化和特征描述。我们通过评估LVC与脑萎缩和疾病持续时间的关系，以及扫描-重扫的可重复性和病变累积的年发生率，比较减法图像分割（SSEG）与连续单时间点传统分割（CSEG）。
对21例多发性硬化症（MS）患者进行了间隔1.5至4.7年的成对扫描。对10例MS患者在30分钟内进行了扫描-重扫MR图像采集。在配准和归一化后，使用CSEG和SSEG测量LVC。变异系数（COV）和Bland-Altman分析估计了方法的可重复性。Spearman等级相关性探究了LVC与其他测量指标之间的关联。
SSEG的萎缩率与净LVC相关（R = -0.446；P <.05），而使用CSEG时则无相关性（R = -0.180；P =.421）。疾病持续时间与CSEG测量的每年净病变体积变化无关联（R = -0.360；P =.11），但与SSEG得出的测量值呈负相关（R = -0.508；P <.05）。SSEG的扫描-重扫COV（0.98% +/- 1.55%）低于CSEG（8.64% +/- 9.91%）。
SSEG揭示了T2加权LVC与伴随的脑萎缩之间的关系，并显示出显著更高的测量可重复性。SSEG是一种有前景的工具，可对病变大小和强度的细微变化进行详细分析，可能为新型治疗的临床试验提供关键的结局指标，并可能为MS的病情进展模式提供进一步的见解。
