Diagnostic accuracy of low-dose and ultra-low-dose CT in detection of chest pathology: a systematic review

Abstract Purpose Studies have evaluated imaging modalities with a lower radiation dose than standard-dose CT (SD-CT) for chest examination. This systematic review aimed to summarize evidence on diagnostic accuracy of these modalities – low-dose and ultra-low-dose CT (LD- and ULD-CT) – for chest pathology. Method Ovid-MEDLINE, Ovid-EMBASE and the Cochrane Library were systematically searched April 29th–30th, 2019 and screened by two reviewers. Studies on diagnostic accuracy were included if they defined their index tests as ‘LD-CT’, ‘Reduced-dose CT’ or ‘ULD-CT’ and had SD-CT as reference standard. Risk of bias was evaluated on study level using the Quality Assessment of Diagnostic Accuracy Studies-2. A narrative synthesis was conducted to compare the diagnostic accuracy measurements. Results Of the 4257 studies identified, 18 were eligible for inclusion. SD-CT (3.17 ± 1.47 mSv) was used as reference standard in all studies to evaluate diagnostic accuracy of LD- (1.22 ± 0.34 mSv) and ULD-CT (0.22 ± 0.05 mSv), respectively. LD-CT had high sensitivities for detection of bronchiectasis (82–96%), honeycomb (75–100%), and varying sensitivities for nodules (63–99%) and ground glass opacities (GGO) (77–91%). ULD-CT had high sensitivities for GGO (93–100%), pneumothorax (100%), consolidations (90–100%), and varying sensitivities for nodules (60–100%) and emphysema (65–90%). Conclusion The included studies found LD-CT to have high diagnostic accuracy in detection of honeycombing and bronchiectasis and ULD-CT to have high diagnostic accuracy for pneumothorax, consolidations and GGO. Summarizing evidence on diagnostic accuracy of LD- and ULD-CT for other chest pathology was not possible due to varying outcome measures, lack of precision estimates and heterogeneous study design and methodology.