Joslyn Stephen, Sullivan Martin, Novellas Rosa, Brennan Nicola, Cameron Gill, Hammond Gawain
Small Animal Hospital, University of Glasgow, Glasgow, UK.
Vet Radiol Ultrasound. 2011 Nov-Dec;52(6):611-8. doi: 10.1111/j.1740-8261.2011.01847.x.
A delay in imaging following intravenous contrast medium administration has been recommended to reduce misdiagnoses. However, the normal variation of contrast enhancement in dogs following a delay has not been characterized. Contrast-enhanced MR imaging of 22 dogs was assessed, in terms of identification of normal anatomic structures, to investigate the variation associated with 10-min delay between contrast medium administration and imaging. All dogs had a normal brain MR imaging study and unremarkable cerebrospinal fluid. Specific regions of interest were assessed both objectively, using computer software, and subjectively using three observers. Mean contrast enhancement > 10% was seen in the pituitary gland, choroid plexus, meninges, temporal muscle, trigeminal nerve, and the trigeminal nerve root. Structures with an active blood-brain barrier had minimal contrast enhancement (< 6%). Enhancing structures had significantly more contrast enhancement at t = 1 min vs. t = 10 min, except in temporal muscle, the trigeminal nerve and the trigeminal nerve root. Interobserver agreement was moderate to good in favor of the initial postcontrast T1-weighted (T1w) sequence. The observers found either no difference or poor agreement in identification of the nonvascular structures. Intraobserver agreement was very good with all vascular structures and most nonvascular structures. A degree of meningeal enhancement was a consistent finding. The initial acquisition had higher enhancement characteristics and observer agreement for some structures; however, contrast-to-noise was comparable in the delayed phase or not significantly different. We provide baseline references and suggest that the initial T1w postcontrast sequence is preferable but not essential should a delayed postcontrast T1w sequence be performed.
建议在静脉注射造影剂后延迟成像，以减少误诊。然而，延迟后犬类造影剂增强的正常变化尚未得到描述。对22只犬进行了对比增强磁共振成像，根据正常解剖结构的识别情况，研究造影剂注射与成像之间10分钟延迟相关的变化。所有犬的脑部磁共振成像检查均正常，脑脊液无异常。使用计算机软件客观评估特定感兴趣区域，并由三名观察者主观评估。垂体、脉络丛、脑膜、颞肌、三叉神经和三叉神经根的平均造影剂增强>10%。具有活跃血脑屏障的结构造影剂增强最小（<6%）。除颞肌、三叉神经和三叉神经根外，增强结构在t = 1分钟时的造影剂增强明显高于t = 10分钟时。观察者间对初始对比后T1加权（T1w）序列的一致性为中度至良好。观察者在非血管结构的识别上未发现差异或一致性较差。观察者内对所有血管结构和大多数非血管结构的一致性非常好。一定程度的脑膜增强是一个一致的发现。初始采集对某些结构具有更高的增强特征和观察者一致性；然而，延迟期的对比噪声相当或无显著差异。我们提供了基线参考，并建议初始T1w对比后序列是优选的，但如果进行延迟的T1w对比后序列，也不是必需的。
