A systematic review of elastography, electrical impedance scanning, and digital infrared thermography for breast cancer screening and diagnosis.

The objective of this study aimed to systematically identify and evaluate all the available evidence of safety, effectiveness and diagnostic accuracy for three emerging classes of technology promoted for breast cancer screening and diagnosis: Digital infrared thermal imaging (DITI), electrical impedance scanning (EIS) and elastography. A systematic search of seven biomedical databases (EMBASE, PubMed, Web of Science, CRD, CINAHL, Cochrane Library, Current Contents Connect) was conducted through March 2011, along with a manual search of reference lists from relevant studies. The principal outcome measures were safety, effectiveness, and diagnostic accuracy. Data were extracted using a standardised form, and validated for accuracy by the secondary authors. Study quality was appraised using the quality assessment of diagnostic accuracy studies tool, while heterogeneity was assessed using forest plots, Cooks' distance and standardised residual scatter plots, and I (2) statistics. From 6,808 search results, 267 full-text articles were assessed, of which 60 satisfied the inclusion criteria. No effectiveness studies were identified. Only one EIS screening accuracy study was identified, while all other studies involved symptomatic populations. Significant heterogeneity was present among all device classes, limiting the potential for meta-analyses. Sensitivity and specificity varied greatly for DITI (Sens 0.25-0.97, Spec 0.12-0.85), EIS (Sens 0.26-0.98, Spec 0.08-0.81) and ultrasound elastography (Sens 0.35-1.00, Spec 0.21-0.99). It is concluded that there is currently insufficient evidence to recommend the use of these technologies for breast cancer screening. Moreover, the high level of heterogeneity among studies of symptomatic women limits inferences that may be drawn regarding their use as diagnostic tools. Future research employing standardised imaging, research and reporting methods is required.