Article
High-resolution ultrasound in the diagnosis of giant cell arteritis
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Published: | September 4, 2017 |
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Background: Giant cell arteritis (GCA) is a systemic vasculitis that affects especially extra-cerebral cranial arteries, but also extracranial vessels. Ultrasound (US) and MRI support diagnostic procedure, but the gold standard remains the histological analysis of a superficial temporal artery (TA) biopsy specimen. The invasive procedure can be associated with false negative results due to a segmental manifestation. We investigated the feasibility of high resolution ultrasound (HRUS) in order to improve the diagnosis of GCA by delineating characteristic, histology-based vessel wall patterns of the TA.
Methods: In addition to standard US at 12-20 MHz and MRI of the TA, n=20 patients (75±6 years) with a suspected GCA received a HRUS with frequencies as high as 70 MHz (VevoMD, Visual Sonics Inc.) prior to biopsy. A concordance analysis was performed on wall layer diameters between histological and HRUS values. The imaging methods were compared with regard to their diagnostic value.
Results: An improved differentiation and metrical assessment of the arterial wall layers (tunica intima, tunica media, tunica adventitia) was possible with the HRUS in patients with active vasculitis (n=14) and negative biopsy (n=6). Pathognomonic alterations of the internal elastic lamina (IEL) could be visualised, showing specific patterns depending on disease status (Figure 1 [Fig. 1]): (A) a continuous double line pattern in healthy vessels, (B) increased double line distance in atherosclerosis, (C) fragmentation of IEL in acute GCA, (D) an additional echogenic band in the media in chronic, untreated GCA, and (E) an echogenic inhomogenous intima without clear border in chronic GCA. These alterations corresponded with findings in histopathology. Diameters measured in histology and HRUS correlated highly for the tunica intima (rccc= 0.78) and moderately for the tunica media (rccc= 0.56). Compared to standard US (86%) and MRI (86%), HRUS had the highest sensitivity (100% consistency with gold standard).
Conclusion: Depicting histological findings along with clear patterns for disease status differentiation, HRUS demonstrated the highest diagnostic value among the compared imaging methods and may potentially replace biopsy in the future.