Abstract：
Mediastinal cysts (MCs) are rare lesions that can arise from embryonic remnants of various mediastinal structures. MCs usually are incidental findings in dogs and cats; however, they can reach a mass-like appearance. The description of MCs on CT in dogs is limited. This retrospective, single-center, descriptive, prevalence study aimed to determine the prevalence of presumed mediastinal cysts (PMCs) in dogs and assess their CT characteristics. Dogs that underwent a thoracic CT scan from January 2019 to August 2021 were included. CT images were evaluated for the presence of PMCs by two diagnostic imaging interns, two last year diagnostic imaging residents, and a board-certified veterinary radiologist. Number, location, margins, shape, volume, size, mass effect, and attenuation values of PMCs were assessed. A total of 866 CT scans were reviewed, and 49 PMCs were identified. The prevalence of PMCs in dogs was 5.66%. English Bulldog and mixed-breed dogs were subjectively overrepresented; however, the possibility of population bias could not be excluded. PMCs were subjectively more frequently observed in male dogs. The PMCs were predominantly round, small, solitary fluid-filled findings localized in the cranioventral mediastinum, with well-defined margins, homogeneous attenuation, and no contrast enhancement. The median attenuation value was 6.32 HU (range: -20.16 to 23.45 HU) precontrast and 7.58 HU (range: -2.45 to 20.79 HU) postcontrast, and the median volume was 1.19 cm3 (range: 0.02-45.32 cm3). Although the prevalence of PMCs was low in our sample population, findings supported prioritizing a differential diagnosis of incidental PMC for dogs with the above imaging characteristics.
摘要：
纵隔囊肿（MC）是罕见的病变，可由各种纵隔结构的胚胎残留物引起。MC通常是狗和猫的偶然发现；然而，它们可以达到块状外观。在狗的CT上对MC的描述是有限的。这次回顾，单中心,描述性,描述性患病率研究旨在确定犬纵隔囊肿(PMC)的患病率,并评估其CT特征.包括从2019年1月至2021年8月接受胸部CT扫描的狗。由两名诊断成像实习生评估CT图像中是否存在PMCs，去年有两名诊断影像住院医师，还有一个委员会认证的兽医放射科医生.编号,location,边距,形状,volume,尺寸,质量效应,并评估了PMC的衰减值。共审查了866次CT扫描，并确定了49家PMC。犬PMC的患病率为5.66%。英国斗牛犬和混血犬在主观上被高估了；但是，不能排除人口偏倚的可能性.在雄性狗中主观上更频繁地观察到PMC。PMC主要是圆形的，小,孤立性充满液体的发现位于颅腹纵隔，有明确的边距，均匀衰减，没有对比度增强。中值衰减值为6.32HU（范围：-20.16至23.45HU）对比前和7.58HU（范围：-2.45至20.79HU）对比后，中位体积为1.19cm3（范围：0.02-45.32cm3）。尽管我们的样本人群中PMC的患病率很低，研究结果支持对具有上述影像学特征的犬优先进行偶发PMC的鉴别诊断.
