Nantes Université, Oniris, CHU Nantes, INSERM, Regenerative Medicine and Skeleton, RMeS, Nantes, France.
Department of Diagnostic Imaging, CRIP, ONIRIS, College of Veterinary Medicine, Food Science and Engineering, Nantes, France.
Vet Radiol Ultrasound. 2023 Sep;64(5):864-872. doi: 10.1111/vru.13288. Epub 2023 Aug 7.
Magnetic resonance imaging is the gold standard for diagnosing intervertebral disc (IVD) degeneration in dogs. However, published methods for quantifying severity or progression of IVD degeneration are currently limited. Mapping MRI sequences are used in humans for quantifying IVD degeneration but have rarely been applied in dogs. The objective of this prospective, method comparison study was to evaluate variable flip angle T1 mapping and multiecho T2 and T2* mapping as methods for quantifying canine lumbar IVD degeneration in twenty canine patients without clinical signs of spinal disease. Ventral and dorsal lumbar IVD widths were measured on radiographs, and lumbar IVDs were assigned a qualitative Pfirrmann grade based on standard T2-weighted sequences. T1, T2, and T2* relaxation times of the nucleus pulposus (NP) were measured on corresponding maps using manual-drawn ROIs. Strong intra- and interrater agreements were found (P < 0.01) for NP relaxation times. Radiographic IVD widths and T1, T2, and T2* mapping NP relaxation times were negatively correlated with Pfirrmann grading (P < 0.01). Significant differences in T1 NP relaxation times were found between Pfirrmann grade I and the other grades (P < 0.01). Significant differences in T2 and T2* NP relaxation times were found between grade I and the other grades and between grades II and III (P < 0.01). Findings indicated that T1, T2, and T2* MRI mapping sequences are feasible in dogs. Measured NP relaxation times were repeatable and decreased when Pfirrmann grades increased. These methods may be useful for quantifying the effects of regenerative treatment interventions in future longitudinal studies.
磁共振成像（MRI）是诊断犬椎间盘（IVD）退变的金标准。然而，目前用于量化 IVD 退变严重程度或进展的方法有限。在人类中，用于量化 IVD 退变的映射 MRI 序列已被广泛应用，但在犬中很少应用。本前瞻性、方法比较研究的目的是评估可变翻转角 T1 映射和多回波 T2 和 T2* 映射，作为定量评估 20 例无脊柱疾病临床症状犬腰椎 IVD 退变的方法。在 X 光片上测量腰椎 IVD 的腹侧和背侧宽度，并根据标准 T2 加权序列对腰椎 IVD 进行 Pfirrmann 分级。使用手动绘制的 ROI 在相应的图谱上测量 NP 的 T1、T2 和 T2弛豫时间。NP 弛豫时间的测量具有很强的组内和组间一致性（P<0.01）。X 光片 IVD 宽度以及 T1、T2 和 T2 映射 NP 弛豫时间与 Pfirrmann 分级呈负相关（P<0.01）。在 Pfirrmann 分级 I 与其他分级之间，以及在分级 II 与分级 III 之间，NP 的 T1 弛豫时间存在显著差异（P<0.01）。在 Pfirrmann 分级 I 与其他分级之间，以及在分级 II 与分级 III 之间，NP 的 T2 和 T2* 弛豫时间也存在显著差异（P<0.01）。结果表明，T1、T2 和 T2*MRI 映射序列在犬中是可行的。NP 的弛豫时间具有可重复性，且随着 Pfirrmann 分级的增加而降低。这些方法可能有助于在未来的纵向研究中量化再生治疗干预的效果。
