【医学知识】你不知道的事：放射学的秘密（6）
《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：血管介入治疗部分和骨组织部分。本期推送的主要内容涉及肌腱肌肉撕裂伤的典型影像诊断以及颅脑CT诊断部分，敬请期待!
51. 原发性骨肿瘤常在干骺端出现，包括巨细胞瘤、软骨母细胞瘤、透明细胞软骨肉瘤。
Primary bone tumorsthat are known to occur in the epiphyseal region include giant cell tumor,chondroblastoma, and clear cell chondrosarcoma.
52. 40岁以下人群中肩袖撕裂伤是十分罕见的，但运动员和外伤患者除外。
（注：肩袖又叫旋转袖，是包绕在肱骨头周围的一组肌腱复合体，肱骨头的前方为肩胛下肌腱，上方为冈上肌腱，后方为冈下肌腱和小圆肌腱，这些肌腱的运动导致肩关节旋内，旋外和上举活动，但更重要的是，这些肌腱将肱骨头稳定于肩胛盂上，对维持肩关节的稳定和肩关节活动起着极其重要的作用。）
Rotator cuff tearsare rare in persons younger than 40 years, except in athletes or in the settingof trauma.
（图为肩袖模式图及MRI）
53.MRI是检测股骨头塌陷前早期骨坏死最敏感的方法。提前发现有利于及时进行关节保留治疗（如减少类固醇摄入），支持疗法（如避免负重）和核心减压。
MRI is the mostsensitive modality for detection of early osteonecrosis, before femoral headcortical collapse. Early detection allows for possible joint-sparing therapiessuch as steroid reduction, supportive therapies such as non-weight-bearing, andcore decompression.
54. MRI通过识别延伸到关节面的内半月板增强信号，来进行半月板撕裂的诊断.
A meniscal tear isdiagnosed on MRI by identifying increased internal meniscal signal intensitythat extends to the articular surface.
(注：半月板1度信号：MRI表现为球形高信号，表明半月板组织的粘液性变和退变，患者无症状，无临床意义)
(注：半月板2度信号：MRI表现为水平走行的线形高信号，是 1度信号的延续，患者亦无临床症状，内侧半月板后角常见）
（注：半月板3度信号：MRI表现为高信号影像至少通向半月板上下表面中的一侧，表示真正的半月板撕裂。矢状位与冠状位相应区域对比有助于辨别2度和3度信号。）
55. 距腓前韧带（外侧韧带复合体的一部分），最常发生扭伤和踝关节韧带撕裂。
The anteriortalofibular ligament, part of the lateral ligamentous complex, is the mostcommonly sprained and torn ankle ligament.
56. 骨髓炎的早期平片表现为软组织肿胀和筋膜平面模糊。7 ~ 10天后，可出现骨环形透明区和骨膜反应。MRI中，骨感染通常被显现为反常骨髓信号区，表现为T1加权低信号、短时间反转恢复序列（STIR）高信号，与正常骨髓正好相反。
Early plain filmfindings of osteomyelitis include soft tissue swelling and blurred fascialplanes. After 7~10 days, bone lucencies and periosteal reaction may be seen. OnMRI, bone infection generally is depicted as a region of abnormal marrowsignal, which is T1 hypointense and short-tau inversion recovery (STIR)hyperintense to normal marrow.
（图为右侧股骨下段慢性硬化型骨髓炎伴死骨形成）
57. 跟腱撕裂后，最有可能进一步造成撕裂伤的肌腱是胫后肌腱（PTT）。
After the Achillestendon, the next most likely ankle tendon to tear is the posterior tibialtendon (PTT).
58. 硬膜外血肿是外科急症。通常由动脉损伤（最常见的脑膜中动脉）引起，常伴有颞骨骨折，局限于外侧缝，通常呈透镜状。硬膜下血肿通常是桥接皮质静脉损伤引起，不局限于外侧缝，通常呈新月的形状。
Epidural hematoma isa surgical emergency. It is usually caused by an arterial injury (most commonlythe middle meningeal artery), often associated with temporal bone fracture,confined by the lateral sutures, and usually lenticular in shape. Subduralhematoma is usually caused by injury to the bridging cortical veins, is notconfined by the lateral sutures, and is usually crescentic in shape.
(图为硬膜外血肿和硬膜下血肿脑CT)
59. HIV患者颅内肿块的鉴别诊断包括弓形体病、其他脑脓肿和淋巴瘤。渐进性多灶性白质脑病和脱髓鞘疾病有时会呈团块状。
The differentialdiagnosis of an intracranial mass in a patient with HIV includes toxoplasmosis,other brain abscess, and lymphoma. Progressive multifocal leukoencephalopathy,a demyelinating disease, can sometimes appear masslike.
（图为脱髓鞘病变脑CT团块影）
60. 急性卒中时头部CT通常表现正常。急性脑梗死最早出现（6小时内）的CT征象是外侧豆状核模糊的灰-白差异消失。急性缺血性改变可在弥散加权MRI出现持续数分钟的强搏动。
Head CT is oftennormal in acute stroke. The earliest sign (within 6 hours) of an acute infarcton CT is loss of the gray-white differentiation with obscuration of the laterallentiform nucleus. Acute ischemic changes can be seen within minutes of onsetof the ictus on diffusion-weighted MRI.
（图为脑出血与梗死的区别）
（图为缺血性脑卒中弥散加权MRI)