Mengozzi E, Burzi M, Miceli M, Lipparini M, Sartoni Galloni S
Unità Operativa di Radiologia I, Dipartimento di Diagnostica per Immagini, Ospedale Maggiore, Azienda Unità Sanitaria Locale, Bologna.
Radiol Med. 2000 Sep;100(3):139-44.
Acute thoracic aortic injuries account for up to 10-20% of fatalities in high-speed deceleration road accidents and have an estimated immediate fatality rate of 80-90%. Untreated survivors to acute trauma (10-20%) have a dismal prognosis: 30% of them die within 6 hours, 40-50% die within 24 hours, and 90% within 4 months. We investigated the diagnostic accuracy of Helical Computed Tomography (Helical CT) in acute traumatic injuries of the thoracic aorta, and the role of this technique in the diagnostic management of trauma patients with a strong suspicion of aortic rupture.
We compared retrospectively the chest Helical CT findings of 256 trauma patients examined June 1995 through August 1999. All patients underwent a plain chest radiograph in supine recumbency when admitted to the Emergency Room. Chest Helical CT examinations were performed according to trauma score, to associated traumatic lesions and to plain chest radiographic findings. All the examinations were performed with no intravenous contrast agent administration and the pitch 2 technique. After a previous baseline study, contrast-enhanced scans were acquired with pitch 1 in 87 patients. All examinations were assessed for the presence of mediastinal hematoma, periaortic hematoma, traumatic pseudodiverticulum, irregular aortic wall or contour and intimal flap as signs of aortic rupture.
Helical CT showed thoracic aortic lesions in 9 of 256 patients examined. In all the 9 cases we found a mediastinal hematoma and all of them had positive plain chest radiographic findings of mediastinal enlargement. Moreover, in 6 cases aortic knob blurring was also evident on plain chest film and in 5 cases depressed left mainstem bronchus and trachea deviation rightwards were observed. All aortic lesions were identified on axial scans and located at the isthmus of level. Aortic rupture was always depicted as pseudodiverticulum of the proximal descending tract and intimal flap. We also found periaortic hematoma in 6 cases and intramural hematoma in 1 case. There were no false positive results in our series: 7 patients with Helical CT diagnosis of aortic rupture were submitted to conventional aortography that confirmed both type and extension of the lesions as detected by Helical CT, and all findings were confirmed by gross inspection at surgery. No false negative results have been recorded so far: untreated aortic ruptures are fatal within 4 months in 90% of patients, or they may evolve into chronic pseudoaneurysm in about 5% of survivors.
In our experience Helical CT had much higher diagnostic sensitivity and specificity than plain chest radiography. In agreement with larger published series, in our small one the diagnostic accuracy of Helical CT was 100% in the evaluation of traumatic aortic ruptures. Moreover, Helical CT is faster and less invasive than conventional aortography, which makes this diagnostic modality increasingly used and markedly improves the management of the serious trauma patient. The more widespread use of this diagnostic tool has permitted to standardize the technique and now Helical CT can be used not only as a screening modality for patients that undergo digital aortography, but also as a reliable diagnostic method for surgical planning.
急性胸主动脉损伤在高速减速道路交通事故致死原因中占比达10 - 20%，估计即时死亡率为80 - 90%。急性创伤后未经治疗而存活的患者（10 - 20%）预后不佳：其中30%在6小时内死亡，40 - 50%在24小时内死亡，90%在4个月内死亡。我们研究了螺旋计算机断层扫描（螺旋CT）在胸主动脉急性创伤性损伤中的诊断准确性，以及该技术在高度怀疑主动脉破裂的创伤患者诊断管理中的作用。
我们回顾性比较了1995年6月至1999年8月期间接受检查的256例创伤患者的胸部螺旋CT检查结果。所有患者在急诊室入院时均进行了仰卧位胸部X线平片检查。胸部螺旋CT检查根据创伤评分、相关创伤性病变及胸部X线平片检查结果进行。所有检查均未静脉注射造影剂，采用螺距2技术。在先前的基线研究之后，87例患者采用螺距1进行了增强扫描。所有检查均评估是否存在纵隔血肿、主动脉周围血肿、创伤性假性憩室、主动脉壁或轮廓不规则以及内膜瓣，作为主动脉破裂的征象。
在256例接受检查的患者中，螺旋CT显示9例存在胸主动脉病变。在所有9例病例中，均发现纵隔血肿，且所有患者胸部X线平片均有纵隔增宽的阳性表现。此外，6例患者胸部X线平片上主动脉结模糊也很明显，5例患者观察到左主支气管压低和气管向右偏移。所有主动脉病变均在轴位扫描上得以识别，且位于峡部水平。主动脉破裂总是表现为降主动脉近端的假性憩室和内膜瓣。我们还发现6例存在主动脉周围血肿，1例存在壁内血肿。本系列研究中无假阳性结果：7例经螺旋CT诊断为主动脉破裂的患者接受了传统主动脉造影，造影证实了螺旋CT检测到的病变类型和范围，所有结果均在手术大体检查中得到证实。目前尚未记录到假阴性结果：未经治疗的主动脉破裂在90%的患者中4个月内致命，或在约5%的幸存者中可能演变为慢性假性动脉瘤。
根据我们的经验，螺旋CT的诊断敏感性和特异性远高于胸部X线平片。与已发表的更大系列研究一致，在我们这个小样本研究中，螺旋CT在评估创伤性主动脉破裂方面的诊断准确性为100%。此外，螺旋CT比传统主动脉造影更快且侵入性更小，这使得这种诊断方式越来越多地被使用，并显著改善了严重创伤患者的管理。这种诊断工具的更广泛应用使得技术得以标准化，现在螺旋CT不仅可以作为接受数字主动脉造影患者的筛查方式，还可以作为手术规划的可靠诊断方法。
