Objective: Use of TA-US for diagnostic investigation of giant cell arteritis (GCA) has been proposed but remains a matter of debate because of the heterogeneous findings. We retrospectively evaluated operating characteristics of temporal artery ultrasonography (TA-US) in a single teaching hospital.
Methods: All subjects with suspected GCA had been seen between 2002 and 2008 and had undergone TA-US with continuous-wave Doppler (until 2004) or color duplex ultrasonography (after 2004), followed within 30 days by a temporal artery biopsy (TAB). TA-US findings were compared with TAB-proven GCA and clinically diagnosed GCA. Results are expressed as sensitivities, specificities, and positive (LR+) and negative likelihood ratios (LR-) of stenoses, occlusions, and the halo sign; for the latter, only color duplex TA-US was considered.
Results: Seventy-seven patients fulfilled the selection criteria; 13 had TAB-proven and 19 had clinically defined GCA. Stenoses/occlusions were seen on 45.5% of TA-US and the halo sign was seen only once (3.2%) in 31 duplex TA-US. Respective sensitivities, specificities, LR+, and LR- for GCA diagnosis (using TAB-proven/clinically defined GCA as reference standards) were 69%/53%, 59%/57%, 1.7/1.2, and 0.5/0.8 for stenoses and/or occlusions, and 17%/10%, 100%/100%, infinite/infinite, and 0.8/0.9 for the halo sign.
Conclusion: The halo sign showed 100% specificity for GCA but only 10%-17% sensitivity. Stenoses/occlusions were of low diagnostic value. These observations suggest that TA-US is neither an effective substitute for TAB nor a reliable screening test to decide which patients can be safely spared TAB.