Magnetic Resonance Angiography vs Ultrasonography in Systemic Large vEssel vasculitiS

The proposed cross sectional study will recruit 50 patients diagnosed with sLVV. All patients recruited to this study will be referrals from outpatient clinic of the Department of Rheumatology, Hospital of Southern Norway Trust. The diagnosis will be based on previous CDUS, MRA, CTA and/or biopsies of the temporal arteries. The patients will be classified according to specific set of classification criteria for GCA (11) or TA (12). The patients will undergo a CDUS evaluation of the supraaortic large vessels and the temporal arteries. In addition, a thorough clinical assessment will be performed at the CDUS visit. A blood sample to test the acute phase response (CRP and ESR) and other biochemical parameters as part of standard care will also be collected.

Within one week after the CDUS evaluation, MRA of the thoracic aorta, the supra-aortic vessels and temporal artery will be performed. The images of both examinations will be uploaded anonymously in a database and two external experts blinded to the patients (one for CDUS and one for MRA) will evaluate the data. The completed evaluation form will be uploaded in the same database.

The ultrasound examination will be performed by using high-end equipment, a Siemens S-2000 with a high, or medium frequency linear (up to 18 MHz for the superficial vessels or medium frequency up to 13 MHz for the deeper vessels) or phased-array transducer (examination of the aorta). The supraaortic vessels and the thoracic aorta will be evaluated by Gadolinium contrast-enhanced T1-weighted spin echo sequence with fat saturation 1.5 Tesla MRI equipment.

In both examinations, a measurement of the intima-media complex (IMC) thickness will be performed. The highest IMC thickness measurement will be recorded in both longitudinal and transverse films (of >3 sec length both in B and color Doppler mode for CDUS). Positive examination will be considered a measurement of IMC thickness >1.5 mm for aorta, carotid, subclavian and >1.0mm for the vertebral and axillary arteries. For the temporal artery, the presence of halo (circumferential, hypoechoic thickness of IMC in transverse/longitudinal view) will be considered as a positive finding. Stenoses of more than 50% in both modalities will also be recorded. Retrograde flow of the vertebral arteries in CDUS examination will be also considered as a positive finding.

Additionally, 100 healthy individuals matched for sex and age to the sLVV patients will be examined in their supraaortic large vessels and temporal arteries by CDUS. The IMC thickness of the healthy individuals will be measured by CDUS, the recordings will be labeled and stored in a database at the Department of Rheumatology, Hospital of Southern Norway Trust, in Kristiansand.

The CDUS and MRA images will be submitted to external experts for evaluation by using a specific evaluation form (Appendix). Both the experts will be blinded to the clinical, laboratory and previous imaging findings of the patients.

In addition, the level of inflammatory cytokines, chemokines and vascular markers (e.g. Vascular Endothelial Growth Factor (VEGF) and Metalloproteinase (MMP) -9) in blood samples of the patients with sLVV will be measured and compared to healthy controls. Whole blood, plasma and serum samples stored at -70 oC will be analyzed for expression of a panel of inflammatory cytokines by Enzyme-linked immunosorbent assay (ELISA) or related methods. Total RNA will be prepared from whole blood. All the blood samples will be stored in Revmabiobank at Hospital of Southern Norway Trust in Kristiansand.

Inclusion criteria

• Patients >18 years
• Diagnosis of large vessel vasculitis based on Ultrasonographic and/or Computed Tomography Angiography and/or Magnetic Resonance Angiography findings or biopsies of the temporal arteries
• Fulfill the classification criteria for Giant Cell Arteritis /Takayasu Arteritis

Exclusion criteria

• Patients <18 years
• Moderate to severe kidney failure
• Known allergic reactions to contrast agents
• Inability to give informed consent