Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA, USA.
Neurology. 2010 Aug 10;75(6):526-31. doi: 10.1212/WNL.0b013e3181eccf8f.
To assess the value of quantitative ultrasound in patients with type 2 and 3 spinal muscular atrophy (SMA).
Twenty-five patients with SMA (15 type 2 and 10 type 3) and 21 normal subjects were enrolled for this observational study. Strength of biceps brachii, wrist extensors, quadriceps, and tibialis anterior were measured with hand-held dynamometry. In addition, these 4 muscles were studied with a standard ultrasound system using a 5-MHz probe, and luminosity values for each muscle and the overlying subcutaneous fat were obtained by subsequent image analysis. A luminosity ratio (LR) for each muscle was calculated by dividing the muscle by the subcutaneous fat luminosity. The LR and strength scores for all 4 muscles were averaged to provide a single summary value for each patient.
The LRs increased with disease severity: 1.27 +/- 0.26 for normal subjects, 2.43 +/- 0.78 for type 3 SMA, and 3.85 +/- 1.3 for type 2 SMA (p < 0.001). Taking all the normal subject and patient data together, there was a good correlation between strength and LR (r = -0.711, p < 0.001). There was also a moderate relationship between LR and strength in the patients with SMA alone (r = -0.588, p = 0.008), and, as expected, a nonsignificant relationship between LR and strength in normal subjects (r = -0.011).
Quantitative ultrasound has the potential of serving as a marker of SMA severity and may be useful in future clinical trials.
评估定量超声在 2 型和 3 型脊髓性肌萎缩症（SMA）患者中的价值。
本观察性研究纳入了 25 例 SMA 患者（15 例 2 型和 10 例 3 型）和 21 名正常对照者。使用手持测力计测量肱二头肌、腕伸肌、股四头肌和胫骨前肌的力量。此外，使用标准超声系统和 5MHz 探头对这 4 块肌肉进行研究，通过随后的图像分析获得每块肌肉和皮下脂肪的亮度值。通过将肌肉的亮度值除以皮下脂肪的亮度值来计算每块肌肉的亮度比值（LR）。将所有 4 块肌肉的 LR 和力量评分平均，为每位患者提供一个单一的综合评分。
LR 随疾病严重程度增加而升高：正常对照者为 1.27±0.26，3 型 SMA 患者为 2.43±0.78，2 型 SMA 患者为 3.85±1.3（p<0.001）。将所有正常对照者和患者的数据放在一起，LR 与力量之间存在良好的相关性（r=-0.711，p<0.001）。在仅患有 SMA 的患者中，LR 与力量之间也存在中度相关性（r=-0.588，p=0.008），而在正常对照者中，LR 与力量之间无显著相关性（r=-0.011）。
定量超声具有作为 SMA 严重程度标志物的潜力，可能在未来的临床试验中有用。
