Treatment deteriorates giant cell arteritis imaging sensitivity
MedWire News: Patients with suspected giant cell arteritis (GCA) should undergo imaging before or as soon as possible after treatment has started to minimize the chance of a false-negative result, advise German researchers.
The team found that corticosteroid treatment quickly and significantly reduces the diagnostic sensitivity of both color-coded duplex sonography (CCDS) and magnetic resonance imaging (MRI) for the disease.
Overall, 36 (61%) of 59 patients were confirmed as having GCA using clinical findings, such as symptom improvement on corticosteroid treatment. When compared with this, CCDS and MRI were 88% and 85% sensitive for GCA, respectively, on day 0-1 of treatment. But CCDS sensitivity fell to 50% on days 2-4 and 5 onwards, and MRI sensitivity fell to 64% and 56%, respectively.
Temporal artery biopsy (TAB) was performed in 41 patients and confirmed diagnosis in 24 (59%) patients. Compared against this gold standard, CCSD sensitivity was 92% on day 0-1 of treatment, falling to 80% on days 2-4 and 50% thereafter. Similarly, MRI sensitivity fell from 90% to 78% and 80%, respectively.
The researchers note that patients received corticosteroid treatment an average of 2.3 days before CCDS and 2.8 days before MRI.
"In contrast to TAB, CCDS and MRI are non-invasive diagnostic methods that can be performed safely and repeatedly," say Thorsten Bley (University Medical Centre Hamburg-Eppendorf) and co-authors.
"However, in terms of feasibility, TAB seems to be a superior investigation despite being invasive treatment can be started and the biopsy can be arranged, for example, within the first week."
They recommend that where imaging is used in patients with suspected GCA, it should be performed within a day of treatment, but emphasize: "Non-invasive imaging must not delay onset of [corticosteroid] treatment."
The findings are published in Rheumatology.
By Lynda Williams