Abstract Background Contrast-enhanced CT is the reference standard used in diagnostic imaging for acute appendicitis in adults. The radiation dose has been of concern. This study aimed to assess whether a lower radiation dose would affect the diagnostic accuracy of CT. Methods This was a prospective single-centre cohort study of patients (aged over 16 years) with suspected appendicitis evaluated for enrolment in concurrent APPAC II–III trials. The diagnostic accuracy of contrast-enhanced low- and standard-dose CT was compared with study protocols guiding imaging based on BMI; this enabled direct CT imaging comparison only in patients with a BMI below 30 kg/m2. The on-call CT diagnosis was compared with the final clinical diagnosis. Results Among all 856 patients investigated, the accuracy of low-dose (454 patients) and standard-dose (402 patients) CT in identifying patients with and without appendicitis was 98·0 and 98·5 per cent respectively. In patients with a BMI under 30 kg/m2, respective values were 98·2 per cent (434 patients) and 98·6 per cent (210 patients) (P = 1·000). The corresponding accuracy for differentiating between uncomplicated and complicated acute appendicitis was 90·3 and 87·6 per cent in all patients, and 89·8 and 88·4 per cent respectively among those with a BMI below 30 kg/m2 (P = 0·663). The median radiation dose in the whole low- and standard-dose CT groups was 3 and 7 mSv respectively. In the group with BMI below 30 kg/m2, corresponding median doses were 3 and 5 mSv (P < 0·001). Conclusion Low- and standard-dose CT were accurate both in identifying appendicitis and in differentiating between uncomplicated and complicated acute appendicitis. Low-dose CT was associated with a significant radiation dose reduction, suggesting that it should be standard clinical practice at least in patients with a BMI below 30 kg/m2.

中文翻译：

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使用低剂量与标准辐射剂量 CT 对疑似急性阑尾炎的诊断准确性：前瞻性队列研究

摘要 背景增强 CT 是成人急性阑尾炎影像诊断的参考标准。辐射剂量一直受到关注。本研究旨在评估较低的辐射剂量是否会影响 CT 的诊断准确性。 方法这是一项前瞻性单中心队列研究，对象是疑似阑尾炎患者（年龄超过 16 岁），评估是否参加同时进行的 APPAC II-III 试验。将对比增强低剂量和标准剂量 CT 的诊断准确性与基于 BMI 指导成像的研究方案进行比较；这使得仅对 BMI 低于 30 kg/m2 的患者进行直接 CT 成像比较成为可能。将待命的 CT 诊断与最终的临床诊断进行比较。 结果在所有接受调查的 856 名患者中，低剂量（454 名患者）和标准剂量（402 名患者）CT 在识别有无阑尾炎患者方面的准确度分别为 98·0 和 98·5%。在BMI低于30 kg/m2的患者中，该值分别为98·2%（434名患者）和98·6%（210名患者）（P = 1·000）。所有患者区分单纯性和复杂性急性阑尾炎的相应准确度分别为 90·3% 和 87·6%，BMI 低于 30 kg/m2 的患者分别为 89·8% 和 88·4%（P = 0） ·663）。整个低剂量CT组和标准剂量CT组的中位辐射剂量分别为3 mSv和7 mSv。BMI低于30 kg/m2组，相应的中位剂量为3和5 mSv（P＜0·001）。 结论低剂量和标准剂量 CT 在识别阑尾炎以及区分单纯性和复杂性急性阑尾炎方面均准确。低剂量 CT 与显着减少辐射剂量相关，这表明至少对于 BMI 低于 30 kg/m2 的患者，低剂量 CT 应该成为标准临床实践。