Musculoskeletal magnetic resonance imaging findings support a common spectrum of giant cell arteritis and polymyalgia rheumatica.

OBJECTIVES: To investigate the proportion and distribution of contrast enhancement (CE) of musculoskeletal structures with MRI of the thorax/abdomen/pelvis in giant cell arteritis (GCA). METHODS: CE at 34 musculoskeletal sites was rated with a 4-point ordinal scale. Patients were divided into groups with/without glucocorticoid (GC) treatment and with/without symptoms of polymyalgia rheumatica (PMR). Two composite scores were created: an MRI-score, including seven sites and a Limited-MRI-score, including four sites. RESULTS: Retrospectively, 90 consecutive patients with GCA were included. The population included 54 and 36 patients with and without PMR symptoms, respectively, and 45 (50%) patients were receiving GCs at the time of MRI. CE was found in 90.7% of lumbar spines, 87.5% of the pelvis, 82.2% of shoulder girdles and in 95.6% at any site in patients without GCs. The proportion of patients without and with GCs with at least moderate enhancement was 91.1%/75.6% at ≥ 1-3, 75.6%/51.1% at ≥ 4-6 and 64.4%/28.9% at ≥ 7-9 sites. The mean difference between the proportion of pathological CE in patients with and without GCs was 27.4% for synovial sites and 18.3% for periarticular/musculotendinous sites. Both composite scores captured substantial differences between groups, correlation was very strong between scores. CONCLUSIONS: MRI shows CE of musculoskeletal structures typical of PMR in most patients with GCA, supporting the concept of "GCA-PMR Spectrum Disease". Changes are more frequent at periarticular/musculotendinous sites and in the presence of PMR symptoms. A clear response to GCs is evident, less so for periarticular/musculotendinous sites.

Diffusion-weighted magnetic resonance imaging for the diagnosis of giant cell arteritis - a comparison with T1-weighted black-blood imaging.

OBJECTIVES: To investigate the diagnostic performance of diffusion-weighted imaging (DWI) of the superficial cranial arteries in the diagnosis of giant cell arteritis (GCA). METHODS: Retrospectively, 156 patients with clinically suspected GCA were included. A new 4-point ordinal DWI rating scale was developed. A post-contrast, fat-suppressed, T1-weighted "black-blood" sequence (T1-BB) was rated for comparison. Ten arterial segments were assessed: common superficial temporal arteries, temporal and parietal branches, occipital and posterior auricular arteries bilaterally. The expert clinical diagnosis after ≥ 6 months of follow-up was the diagnostic reference standard. Diagnostic accuracy was evaluated for different rating methods. RESULTS: The study cohort consisted of 87 patients with and 69 without GCA. For DWI, the area under the curve was 0.90. For a cut-off of ≥ 2 consecutive pathological slices, DWI showed a sensitivity of 75.9%, a specificity of 94.2% and a positive likelihood ratio of 13.09. With a cut-off of ≥ 3 consecutive pathological slices, sensitivity was 70.1%, specificity was 98.6%, and the positive likelihood ratio was 48.38. For the T1-BB, values were 88.5%, 88.4% and 7.63, respectively. The inter-rater analysis for DWI with a cut-off of ≥ 2 pathological slices showed a kappa of 1.00 on the patient level and 0.85 on the arterial segment level. For the T1-BB the kappa was 0.78 and 0.79, respectively. CONCLUSION: DWI of the superficial cranial arteries demonstrates a good diagnostic accuracy and reliability for the diagnosis of GCA. DWI is widely available and can be used immediately in clinical practice for patients with suspected GCA.

DWI scrolling artery sign for the diagnosis of giant cell arteritis: a pattern recognition approach.

OBJECTIVES: To investigate the diagnostic accuracy of a pattern recognition approach for the evaluation of MRI scans of the head with diffusion-weighted imaging (DWI) in suspected giant cell arteritis (GCA). METHODS: Retrospectively, 156 patients with suspected GCA were included. The 'DWI-Scrolling-Artery-Sign' (DSAS) was defined as hyperintense DWI signals in the cranial subcutaneous tissue that gives the impression of a blood vessel when scrolling through a stack of images. The DSAS was rated by experts and a novice in four regions (frontotemporal and occipital, bilaterally). The temporal, occipital and posterior auricular arteries were assessed in the T1-weighted black-blood sequence (T1-BB). The diagnostic reference was the clinical diagnosis after ≥6 months of follow-up. RESULTS: The population consisted of 87 patients with and 69 without GCA; median age was 71 years and 59% were women. The DSAS showed a sensitivity of 73.6% and specificity of 94.2% (experts) and 59.8% and 95.7% (novice), respectively. Agreement between DSAS and T1-BB was 80% for the region level (499/624; kappa(κ)=0.59) and 86.5% for the patient level (135/156; κ=0.73). Inter-reader agreement was 95% (19/20; κ=0.90) for DSAS on the patient level and 91.3% (73/80; κ=0.81) on the region level for experts. For expert versus novice, inter-reader agreement for DSAS was 87.8% on the patient level (137/156; κ=0.75) and 91.2% on the region level (569/624; κ=0.77). CONCLUSIONS: The DSAS can be assessed in less than 1 min and has a good diagnostic accuracy and reliability for the diagnosis of GCA. The DSAS can be used immediately in clinical practice.

Ultrasound intima-media thickness cut-off values for the diagnosis of giant cell arteritis using a dual clinical and MRI reference standard and cardiovascular risk stratification.

Objectives: To derive segmental cut-off values and measures of diagnostic accuracy for the intima-media thickness of compressed temporal artery segments for the diagnosis of giant cell arteritis (GCA) on the patient level. To examine the influence of cardiovascular risk. Methods: Retrospectively, patients evaluated for GCA with an ultrasound of the temporal arteries and an MRI of the head, including a T1-fatsat-black blood (T1-BB) sequence, were identified and classified based on cardiovascular risk and a dual reference standard of T1-BB on the segmental level and the clinical diagnosis on the patient level. Intima-media thickness of the common superficial temporal artery (CSTA), frontal and parietal branches (FB, PB) were measured by compression technique. Statistically and clinically optimal (specificity of approx. 90% for the patient level) cut-offs were derived. Diagnostic accuracy was evaluated on the patient level. Results: The population consisted of 144 patients, 74 (51.4%) with and 70 (48.6%) without GCA. The statistically optimal cut-offs were 0.86 mm, 0.68 mm and 0.67 mm for the CSTA, the FB and PB, respectively. On the patient level sensitivity and specificity were 86.5 and 81.4%. Clinically optimal cut-offs were 1.01 mm, 0.82 mm and 0.69 mm and showed a sensitivity of 79.7% and a specificity of 90.0%. For patients without high cardiovascular risk, statistically optimal cut-offs showed a sensitivity of 89.6% and a specificity of 90.5%. Conclusion: Newly derived ultrasound intima-media thickness cut-offs with a dual reference standard show high diagnostic accuracy on the patient level for the diagnosis of GCA, particularly in patients without high cardiovascular risk.