Howarth D M, Booker J A, Voutnis D D
Department of Nuclear Medicine, Hunter Imaging Group, Pacific Medical Imaging, Newcastle, New South Wales, Australia.
Intern Med J. 2006 May;36(5):281-8. doi: 10.1111/j.1445-5994.2006.01070.x.
To determine the optimal diagnostic cut-off point using a simplified criterion for the detection of pulmonary embolus (PE) and to evaluate the criterion's utility and reporter reproducibility.
Lung scintigraphy was carried out in 924 patients for the diagnosis of PE. This group consisted of 316 men and 608 women with median age of 63 years (range 18-94 years). Ventilation imaging was carried out with Tc-99m Technegas followed by perfusion imaging using 190 MBq Tc-99m macroaggregated albumin. Studies were classified using a 6-category probability criterion of incremental ventilation/perfusion (V/Q) mismatch: A, normal; B, low (minor matched V/Q defects or segmental matched V/Q defects without opacity on chest X-ray); C, low-moderate (a partial segment of V/Q mismatch); D, moderate (1 segment of mismatch); E, moderate-high (1-2 segments of V/Q mismatch) and F, high probability (=2 segments of V/Q mismatch). Clinical end-points at 3 and 6 months were death by PE or PE treated with anticoagulation therapy. Three-reporter reproducibility was determined by kappa statistic on a subgroup of patients (53/924).
A total of 122 patients (13%) had a confirmed diagnosis of PE at 3 months and no additional cases were registered at 6 months. The lung scintigraphy probability classification showed: normal 152 (16%), low 620 (67%), low-moderate 20 (2%), moderate 28 (3%), moderate-high 24 (3%) and high 80 (9%). The respective sensitivities and specificities, where the diagnostic cut-offs were established at F, high; E, moderate-high; D, moderate and C, low-moderate probability, were F, 64 and 100%; E, 82 and 99%; D, 95 and 98% and C, 98 and 96%. The respective false-negative cases for F, E, D and C cut-offs were 44, 22, 7 and 3. Using the revised Prospective Investigation of Pulmonary Embolism Diagnosis reporting classification reporter agreement showed kappa values of 0.31-0.48. Using a simplified 2-category (>0.5 segment of V/Q mismatch positive, all others negative) criterion resulted in a higher reporting agreement (kappa 0.74-0.83). There were only 3% of indeterminate cases if this was defined by the D category and a maximum of 8% if categories C, D and E were included.
Using a simplified diagnostic criterion where all studies showing >0.5 segments of V/Q mismatch are regarded as positive and all others as negative, lung scintigraphy, incorporating Tc-99m Technegas ventilation imaging or its equivalent, can achieve a very high diagnostic accuracy for the detection of PE. Using this technique, less than 5% of scans are indeterminate. A simplified, unambiguous approach to reporting is recommended.
使用简化标准确定检测肺栓塞（PE）的最佳诊断临界点，并评估该标准的效用及报告者间的可重复性。
对924例患者进行肺闪烁扫描以诊断PE。该组包括316名男性和608名女性，中位年龄63岁（范围18 - 94岁）。通气显像采用锝 - 99m聚合气体，随后灌注显像使用190MBq锝 - 99m大聚合白蛋白。研究根据通气/灌注（V/Q）不匹配的6类概率标准进行分类：A，正常；B，低（轻微匹配的V/Q缺陷或胸部X线无实变的节段性匹配V/Q缺陷）；C，低 - 中度（V/Q不匹配的部分节段）；D，中度（1个节段不匹配）；E，中度 - 高度（1 - 2个节段V/Q不匹配）和F高概率（= 2个节段V/Q不匹配）。3个月和6个月时的临床终点为死于PE或接受抗凝治疗的PE。通过kappa统计量在一组患者（53/924）中确定报告者间的可重复性。
共有122例患者（13%）在3个月时确诊为PE，6个月时未登记到其他病例。肺闪烁扫描概率分类显示：正常152例（16%），低620例（67%），低 - 中度20例（2%），中度28例（3%），中度 - 高度24例（3%）和高80例（9%）。当诊断临界点分别设定为F高、E中度 - 高度、D中度和C低 - 中度概率时，各自的敏感性和特异性分别为：F，64%和100%；E，82%和99%；D，95%和98%；C，98%和96%。F、E、D和C临界点各自的假阴性病例数分别为44、22、7和3。使用修订后的肺栓塞诊断前瞻性调查报告分类，报告者间一致性的kappa值为0.31 - 0.48。使用简化的2类标准（V/Q不匹配阳性>0.5个节段，其他均为阴性）导致更高的报告一致性（kappa 0.74 - 0.83）。如果将不确定病例定义为D类，仅占3%；如果包括C、D和E类，最多占8%。
采用简化诊断标准，即所有显示V/Q不匹配>0.5个节段的研究视为阳性，其他均视为阴性，结合锝 - 99m聚合气体通气显像或其等效方法的肺闪烁扫描，对检测PE可实现非常高的诊断准确性。使用该技术，不到5%的扫描结果不确定。建议采用简化、明确的报告方法。
