【医学知识】你不知道的事：放射学的秘密（8）
《Radiology Secrets Plus》是由宾夕法尼亚大学E. Pretorius和Jeffrey Solomon博士主编的以问答形式深入浅出的介绍相关放射性与影像诊断学内容的图书。该书总结了影像诊断学在实践过程中需要注意的100个知识要点，本公众号将持续推送翻译介绍。上一期我们介绍了：各种影像学检查方法的应用。本期推送的主要内容涉及核医学等辅助性影像诊断方法以及儿科影像，敬请期待!
71. 将肺通气灌注（V&SOL；Q）扫描作为肺栓塞（PE）的“高概率”诊断方法。扫描必须相当于两个或多个较大的节段性灌注缺损（75～100%个受累段），且这些异常与通气异常不匹配。四个或更多的中等大小的灌注缺损（25～75%的受累段）也提示有很高的可能性出现PE。扫描提示高概率意味着有超过80%患有肺栓塞的可能。（附：肺通气显像是通过吸入99m锝标记的气溶胶或放射性气体(如81s氪)来显示肺通气分布情况。临床上用于了解呼吸道的通畅情况及各种肺疾病的通气功能，也可用于估价药物或手术治疗前后的局部肺通气功能，以指导治疗和观察疗效，常常与肺灌注显像配合，用于肺栓塞和阻塞性肺病的诊断和鉴别诊断。）
To classify a ventilation-perfusion (V/Q) scan as a “high probability” for pulmonary embolism (PE), the scan must have the equivalent of two or more large segmental perfusion defects (75~100% involvement of the segment) that are not matched by ventilatory abnormalities. Four or more moderately sized perfusion defects (25~75% involvement of the segment) would also represent a high probability for PE. The implication of a high probability scan suggests a greater than 80% chance of having a PE.
图中左肺下叶为带状灌注缺损
72. 年轻男性甲状腺“冷结节”患者患癌可能性高于那些有类似发现的老年女性患者。颈部暴露于辐射也是冷结节发生癌变的一个重要危险因素。此外，美国发现在冷结节内混合囊性和固体成分也更容易诱发甲状腺癌。而多结节性甲状腺肿下的冷结节与其他冷结节相比基本上不可能患癌。（附：甲状腺结节是一种非常常见的病症，特别是在中年女性中较多见。据了解目前对甲状腺结节有多种检测方法，其中以放射性核素检查最常用，可观察到甲状腺的大小、位置、形态和131碘化钠吸收后分布的情况。放射性核素扫描根据结节对放射性核素的摄取能力将甲状腺结节分4类，凉结节、热结节、温结节和冷结节。）
Younger male patients with “cold” thyroid nodules are more likely to have cancer than are older female patients with similar findings. Exposure of the neck to radiation is also an important risk factor for cancer in a cold nodule. Finally, US findings of mixed cystic and solid components within a cold nodule are also more suggestive of thyroid cancer. Cold nodules in the setting of a multinodular goiter are substantially less likely to be cancer than other cold nodules.
图左甲状腺左叶有冷色缺损；图中缺损更为明显且有较大占位区域；图右提示左叶活度不足
73.肾移植术后急性肾小管坏死（ATN）几乎立即发生，而慢性排斥反应发生在几天到几周后甚至更长的时间。ATN患者肾灌注正常或只有轻微的减少和皮质通过时间（尿出当前采集系统的时间）延迟。排斥反应通常与皮质功能减弱引起的血流减少有关。
After renal transplantation, acute tubular necrosis (ATN) occurs almost immediately, whereas chronic rejection occurs over several days to weeks or even longer. Patients with ATN have normal or only slightly diminished perfusion of the kidney with a delayed cortical transit time (how long it takes for urine to appear in the collecting system). Rejection usually is associated with diminished flow with mildly impaired cortical function.
74.运动压力测试应在下述条件时停止：（1）病人因为呼吸困难、胸痛、疲乏、肌肉骨骼问题不能继续测试；（2）病人有高血压反应；（3）患者出现大于3毫米的ST段压低；（4）患者有ST段抬高，提示有心肌梗死的可能；（5）病人有潜在危险的心律失常，如室性心动过速、心室颤动发作、非常快速的室上性心动过速或心脏传导阻滞。
An exercise stress test should be stopped when (1) the patient cannot continue because of dyspnea, chest pain, fatigue, or musculoskeletal problems; (2) the patient has a hypertensive response; (3) the patient develops ST segment depressions of greater than 3 mm; (4) the patient has ST segment elevation, heralding a possible myocardial infarction; or (5) the patient experiences the onset of a potentially dangerous arrhythmia such as ventricular tachycardia, ventricular fibrillation, very rapid supraventricular tachycardia, or heart block.
75. 右位主动脉弓与法洛氏四联症（TOF）和永存动脉干（TA）有关联，但与TA的联系更为密切。因为法洛氏四联症比较常见，所以我们更多地会在法洛氏四联症中见到右位主动脉弓。
（附：永存动脉干，又称共同动脉干，属少见的先天畸形。由于胚胎发育缺陷，未能将原始动脉干分隔成主动脉和肺动脉，而留下共同的动脉干，且只有一组半月瓣跨于两心室之上，常同时有高位室间隔缺损。从动脉干升部发出左、右肺动脉，远端再发出头臂动脉。肺充血型系指除外动脉干不发出肺动脉者。体循环静脉血进入右房右室而喷入动脉干；肺循环静脉血流回左房左室后亦进入动脉干。肺血流量增多、肺动脉压力增高。）
A right-sided arch is associated with both tetralogy of Fallot (TOF) and truncus arteriosus (TA), but is more closely associated with TA. Since TOF is more common, however, you are more likely to see a right-sided arch with TOF.
76. 杓会厌襞增厚与会厌增厚提示会厌炎并允许紧急气管插管。
Thickened aryepiglottic folds with a thickened epiglottis are indicative of epiglottitis and warrant emergent intubation.
77. 如果怀疑有异物吸入，此时应该使用双边侧卧影像进行诊断。正常的肺会压缩体积，而阻塞的肺会保持透亮和膨胀。
If you suspect an aspirated foreign body, you should order bilateral lateral decubitus films. A normal lung will lose volume, whereas an obstructed lung will remain lucent and inflated.
78.在普通X线成像中的双泡征代表含有空气或液体膨胀的胃和十二指肠球部，见于旋转不良、十二指肠闭锁和空肠闭锁。
The double-bubble sign on plain films represents an air- or fluid-filled distended stomach and duodenal bulb. It is seen in malrotation, duodenal atresia, and jejunal atresia.
79.在小于6岁的幼儿的正常大小的眼球，如果中发现斑点钙化且无其他发现，则提示视网膜母细胞瘤。
A fleck of calcium in a normal-sized globe of a child younger than 6 years is characteristic of retinoblastoma until proven otherwise.
80.在小儿肘关节中，一般肱骨内上髁骨化中心出现在滑车骨化中心之前。如果在内上踝骨化中心的滑车区出现成骨密度，那么这是一个撕脱的骨片段。
In a pediatric elbow, the medial epicondyle ossification center appears before the trochlear ossification center. If you see an ossific density in the region of the trochlea in the absence of a medial epicondylar ossification center, this is an avulsed fragment.