Center for Depression, Anxiety and Stress Research, McLean Hospital, Belmont, Massachusetts, USA.
McLean Imaging Center, McLean Hospital, Belmont, Massachusetts, USA.
Magn Reson Med. 2021 May;85(5):2359-2369. doi: 10.1002/mrm.28587. Epub 2020 Nov 20.
Gamma-aminobutyric acid (GABA) abnormalities have been implicated in a range of neuropsychiatric disorders. Despite substantial interest in probing GABA in vivo, human imaging studies relying on magnetic resonance spectroscopy (MRS) have generally been hindered by technical challenges, including GABA's relatively low concentration and spectral overlap with other metabolites. Although past studies have shown moderate-to-strong test-retest repeatability and reliability of GABA within certain brain regions, many of these studies have been limited by small sample sizes.
GABA+ (macromolecular-contaminated) test-retest reliability and repeatability were assessed via a Meshcher-Garwood point resolved spectroscopy (MEGA-PRESS) MRS sequence in the rostral anterior cingulate cortex (rACC; n = 21) and dorsolateral prefrontal cortex (dlPFC; n = 20) in healthy young adults. Data were collected on a 3T scanner (Siemens Prisma, Siemens Healthcare, Erlangen, Germany) and GABA+ results were reported in reference to both total creatine (GABA+/tCr) and water (GABA+/water).
Results showed strong test-retest repeatability (mean GABA+/tCr coefficient of variation [CV] = 4.6%; mean GABA+/water CV = 4.0%) and reliability (GABA+/tCr intraclass correlation coefficient [ICC] = 0.77; GABA+/water ICC = 0.87) in the dlPFC. The rACC showed acceptable (but comparatively lower) repeatability (mean GABA+/tCr CV = 8.0%; mean GABA+/water CV = 7.5%), yet low-moderate reliability (GABA+/tCr ICC = 0.40; GABA+/water ICC = 0.44).
The present study found excellent GABA+ MRS repeatability and reliability in the dlPFC. The rACC showed inferior results, possibly because of a combination of shimming impedance and measurement error. These data suggest that MEGA-PRESS can be utilized to reliably distinguish participants based on dlPFC GABA+ levels, whereas the mixed results in the rACC merit further investigation.
γ-氨基丁酸（GABA）异常与多种神经精神疾病有关。尽管人们对体内 GABA 进行了大量研究，但依赖磁共振波谱（MRS）的人体成像研究通常受到技术挑战的限制，包括 GABA 浓度相对较低以及与其他代谢物的光谱重叠。尽管过去的研究表明，在某些脑区，GABA 的测试-重测重复性和可靠性为中等至强，但这些研究中的许多都受到样本量小的限制。
通过在健康年轻成年人的额前扣带皮层（rACC；n=21）和背外侧前额叶皮层（dlPFC；n=20）中使用 Meshcher-Garwood 点分辨波谱（MEGA-PRESS）MRS 序列，评估 GABA+（受大分子污染）的测试-重测重复性和可靠性。数据是在 3T 扫描仪（西门子 Prisma，西门子医疗，德国埃朗根）上采集的，并以总肌酸（GABA+/tCr）和水（GABA+/water）为参考报告 GABA+结果。
结果显示，dlPFC 具有很强的测试-重测重复性（GABA+/tCr 变异系数 [CV]平均值为 4.6%；GABA+/water CV 平均值为 4.0%）和可靠性（GABA+/tCr 组内相关系数 [ICC]为 0.77；GABA+/water ICC 为 0.87）。rACC 显示出可接受的（但相对较低）重复性（GABA+/tCr CV 平均值为 8.0%；GABA+/water CV 平均值为 7.5%），但可靠性较低-中等（GABA+/tCr ICC 为 0.40；GABA+/water ICC 为 0.44）。
本研究在 dlPFC 中发现了出色的 GABA+MRS 重复性和可靠性。rACC 的结果较差，可能是由于匀场阻抗和测量误差的综合影响。这些数据表明，MEGA-PRESS 可用于可靠地区分基于 dlPFC GABA+水平的参与者，而 rACC 的混合结果则需要进一步研究。
