A novel model to assess disease activity in Takayasu arteritis based on 18F-FDG-PET/CT: a Chinese cohort study

Association of PET vascular activity score with Takayasu's arteritis angiographic progression

OBJECTIVE

Arterial wall Fluorodeoxyglucose (FDG) uptake can reflect vascular inflammation in Takayasu's arteritis (TAK); however, its association with vascular prognosis remains unclear. This study assessed the predictive efficacy of the PET vascular activity score (PETVAS) for vascular prognosis and whether FDG uptake in specific arterial territories was associated with angiographic progression in TAK.

METHODS

Patients with TAK from a prospective observational cohort who underwent 18F-FDG PET/CT and serological tests at baseline were included. Magnetic Resonance Angiography and/or Contrast-Enhanced Ultrasound were conducted at baseline and every six months during follow-up. The PETVAS was calculated. New/aggravated lesions were considered as angiographic progression.

RESULTS

The imaging evaluation included 1,353 arterial territories from 123 patients. The baseline PETVAS was positively correlated with Erythrocyte Sedimentation Rate (ESR), serum IL-6, and Platelet. Angiographic progression was noted in 45 patients (36.6%) with 72 territories (5.3%) during 30 (18-72) months of follow-up. Of these, 19 (42.2%) had baseline PETVAS > 15, including 84.2% (16/19) naïve cases and 78.9% (15/19) with ESR ≥ 30 mm/h. Multivariate Cox proportional hazards regression analysis adjusted for age and sex showed baseline PETVAS > 15 (HR 1.93; 95% CI, 1.01-3.68; p = 0.04) an independent predictor of angiographic progression.

CONCLUSION

Baseline PETVAS > 15 was an independent predictor of angiographic progression in TAK. Baseline FDG uptake in specific arterial territories did not correlate with vascular progression. Our study provides a feasible PET/CT-based predictive marker for vascular progression in TAK and underscores the importance of regular imaging follow-up to monitor disease outcomes.

CLINICAL TRIAL NUMBER

Not applicable.

Positron Emission Tomography in Takayasu Arteritis: A Review Including Patterns of Vascular Involvement Across Modalities and Regions

Takayasu arteritis (TAK) is a rare, chronic large-vessel vasculitis that predominantly affects the aorta and its major branches. Early and accurate diagnosis remains essential to prevent irreversible vascular damage and organ dysfunction. Positron emission tomography/computed tomography (PET/CT) has emerged as a valuable imaging modality for detecting active vascular inflammation in TAK. Using 18F-fluorodeoxyglucose (18F-FDG), PET/CT enables the assessment of metabolic activity in inflamed arterial walls, supporting both initial diagnosis and disease monitoring. Compared with conventional imaging techniques, such as magnetic resonance imaging (MRI) and computed tomography (CT), PET/CT provides functional data correlated with inflammatory activity rather than solely anatomical changes. Recent studies have highlighted its utility in distinguishing active from chronic disease, predicting relapse, and evaluating treatment response. This review summarizes the role of PET/CT in TAK, addressing its advantages, patterns of vascular involvement, limitations, and future perspectives. Vascular lesions identified using PET/CT do not always align with those detected by other imaging modalities, with PET/CT demonstrating superiority in revealing aortic inflammation potentially overlooked by alternative techniques. Further research is needed to establish whether PET/CT-based vascular involvement patterns, rather than conventional angiographic findings, can help identify disease subtypes of TAK.

18F-FDG-PET/MR imaging to monitor disease activity in large vessel vasculitis

Disease-monitoring in large vessel vasculitis (LVV) is challenging. Simultaneous 18F-fluorodeoxyglucose positron emission tomography with magnetic resonance imaging (PET/MRI) provides functional assessment of vascular inflammation alongside high-definition structural imaging with a relatively low burden of radiation exposure. Here, we investigate the ability of PET/MRI to monitor LVV disease activity longitudinally in a prospective cohort of patients with active LVV. We demonstrate that both the PET and MRI components of the scan can distinguish active from inactive disease using established quantification methods. Using logistic-regression modelling of PET/MRI metrics, we devise a novel PET/MRI-specific Vasculitis Activity using MR PET (VAMP) score which is able to distinguish active from inactive disease with more accuracy than established methods and detects changes in disease activity longitudinally. These findings are evaluated in an independent validation cohort. Finally, PET/MRI improves clinicians' assessment of LVV disease activity and confidence in disease management, as assessed via clinician survey. In summary, PET/MRI may be useful in tracking disease activity and assessing treatment-response in LVV. Based on our findings, larger, prospective studies assessing PET/MRI in LVV are now warranted.

Interleukin 6 Levels and Disease Activity in Takayasu Arteritis: A Systematic Review With Meta-analysis

BACKGROUND

Various studies have suggested interleukin 6 (IL-6) as a potential biomarker for detecting disease activity in Takayasu arteritis.

METHODS

A systematic review and meta-analysis was performed to assess differences in IL-6 levels in patients with active (aTA) and inactive Takayasu arteritis (iTA), as well as healthy controls (HCs), using validated activity scores. Study quality and the risk of bias were assessed using STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) and the Newcastle-Ottawa and Joanna Briggs checklist, respectively. For the meta-analysis, we pooled the raw mean IL-6 levels in each group and then estimated and pooled the crude mean differences between the groups. We applied a random-effects model in all analyses.

RESULTS

Of the 93 eligible articles, 10 were included after removing duplicates and studies that met the exclusion criteria. Overall, 1825 patients with a mean age ranging from 24 to 40.6 years were included. The pooled levels of IL-6 increased depending on disease activity as follows: HCs: 3.08 (95% confidence interval [CI], 0.88-5.28), iTA: 7.21 (3.61-10.82), and aTA: 22.67 (12.44-32.91) pg/mL. Patients with aTA had higher IL-6 levels than HCs (21.52 [95% CI, -0.43 to 43.47]) and those with iTA (16.69 [95% CI, 5.32-28.06]), whereas IL-6 levels were not different between HCs and patients with iTA (3.62 [95% CI, -13.18 to 20.42]).

CONCLUSIONS

Interleukin 6 levels are significantly increased in patients with aTA compared with those with iTA and HCs but not in patients with iTA compared with HCs. More studies are needed to establish the IL-6 cutoff value for assessing disease activity.

PET vascular activity score for predicting new angiographic lesions in patients with Takayasu arteritis: a Chinese cohort study

OBJECTIVE

To investigate the ability of 18F-fluorodeoxyglucose PET/CT to predict new lesions in Takayasu arteritis.

METHODS

Eighty-two Chinese patients with newly diagnosed Takayasu arteritis were recruited. Their clinical characteristics, serum biomarkers and imaging results were recorded at baseline and every visit. They were followed up for at least 2 years. New angiographic lesions were evaluated by magnetic resonance angiography. Baseline PET vascular activity scores (PETVAS) for predicting new lesions were evaluated.

RESULTS

At baseline, a moderate correlation was observed between PETVAS and ESR (r = 0.74, P < 0.01) and CRP level (r = 0.69, P < 0.01). Overall, 18 (22%) patients showed new lesions on imaging during a median follow-up time of 36 months. The median time to the first occurrence of new lesions was 18 months. Compared with patients without new lesions, the patients with new lesions included more female patients (67.2% vs 94.4%, P = 0.03), patients with higher ESR values (20 vs 49, P = 0.02) and patients with active disease (62.5% vs 94.4%, P < 0.01). Multivariate Cox regression analysis revealed PETVAS was an independent risk factor for new angiographic lesions (PETVAS ≥8, hazard ratio = 7.56; 95% CI 2.20, 26.01, P < 0.01) with adjustment of age, sex, chest pain, ESR and Physician Global Assessment. Furthermore, patients with PETVAS ≥8 at baseline were more likely to experience adverse events including arterial ischaemic events during the follow-up.

CONCLUSION

PETVAS showed good performance in predicting new lesions in Takayasu arteritis.

An exploration of the feasibility and clinical value of half-dose 5-h total-body 18F-FDG PET/CT scan in patients with Takayasu arteritis

PURPOSE

To explore the feasibility and clinical value of 5-h delayed 18F-fluorodeoxyglucose (18F-FDG) total-body (TB) positron emission tomography/computed tomography (PET/CT) in patients with Takayasu arteritis (TA).

METHODS

This study included nine healthy volunteers who underwent 1-, 2.5-, and 5-h triple-time TB PET/CT scans and 55 patients with TA who underwent 2- and 5-h dual-time TB PET/CT scans with 1.85 MBq/kg 18F-FDG. The liver, blood pool, and gluteus maximus muscle signal-to-noise ratios (SNRs) were calculated by dividing the SUVmean by its standard deviation to evaluate imaging quality. TA lesions' 18F-FDG uptake was graded on a three-point scale (I, II, III), with grades II and III considered positive lesions. Lesion-to-blood maximum standardised uptake value (SUVmax) ratio (LBR) was calculated by dividing the lesion SUVmax by the blood pool SUVmax.

RESULTS

The liver, blood pool, and muscle SNR of the healthy volunteers at 2.5- and 5-h were similar (0.117 and 0.115, respectively, p = 0.095). We detected 415 TA lesions in 39 patients with active TA. The average 2- and 5-h scan LBRs were 3.67 and 7.59, respectively (p < 0.001). Similar TA lesion detection rates were noted in the 2-h (92.0%; 382/415) and 5-h (94.2%; 391/415) scans (p = 0.140). We detected 143 TA lesions in 19 patients with inactive TA. The 2- and 5-h scan LBRs were 2.99 and 5.71, respectively (p < 0.001). Similar positive detection rates in inactive TA were noted in the 2-h (97.9%; 140/143) and 5-h (98.6%; 141/143) scans (p = 0.500).

CONCLUSION

The 2- and 5-h 18F-FDG TB PET/CT scans had similar positive detection rates, but both combined could better detect inflammatory lesions in patients with TA.

Metabolic inflammatory volume and total inflammatory glycolysis: novel parameters to evaluate PET-CT disease activity in Takayasu arteritis

OBJECTIVES

To evaluate diagnostic accuracy for active Takayasu arteritis (TAK) for two novel 18F-fluorodeoxyglucose PET-CT parameters, the inflammatory volume (MIV) and total inflammatory glycolysis (TIG), to quantitate volume of metabolically-active arterial tissue.

METHODS

From a cohort of TAK (n = 36, 35 immunosuppressive-naïve), images of PET-CTs were reviewed for mean and maximum standardized uptake value (SUVmean and SUVmax), target-to-blood pool ratio (TBR), target-to-liver ratio (TLR), and PET Vasculitis Activity Score (PETVAS). Regions of interest were drawn to semiautomatically calculate MIV in areas of 18F-fluorodeoxyglucose uptake ≥ 1.5 SUVmean after excluding physiological tracer uptake. TIG was calculated by multiplying MIV with SUVmean. PET-CT parameters, ESR, CRP, and clinical disease activity scores were compared against the gold standard of physician global assessment of disease activity (PGA, active/inactive).

RESULTS

Using dichotomized cut-offs for active TAK at SUVmax (≥ 2.21), SUVmean (≥ 1.58), TBR (≥ 2.31), TLR (≥ 1.22), PETVAS (various cut-offs), ESR (≥ 40 mm/hour), and CRP (≥ 6 mg/L), the novel indices MIV (≥ 1.8) and TIG (≥ 2.7) performed similar [area under the receiver operating characteristics curve (AUC) 0.873 for both] to SUVmax (AUC 0.841) and SUVmean (AUC 0.851), and better than TBR (AUC 0.773), TLR (AUC 0.773), PETVAS [≥ 5.5 (AUC 0.750), ≥ 10 (AUC 0.636), ≥ 15 (AUC 0.546)], ESR (AUC 0.748), or CRP (AUC 0.731). MIV and TIG had similar agreement with PGA or CRP as with SUVmax or SUVmean, and better agreement than TBR, TLR, or PETVAS cut-offs.

CONCLUSIONS

MIV and TIG performed similarly, therefore, are viable alternatives to existing PET-CT parameters to assess TAK disease activity in this preliminary report. Key Points • MIV and TIG performed similar to SUVmax and SUVmax for disease activity assessment in TAK. • MIV and TIG distinguished active TAK better than TBR, TLR, PETVAS cut-offs, ESR, or CRP. • MIV and TIG had better agreement with PGA or CRP than TBR, TLR, or PETVAS cut-offs.

The role of PET/CT in disease activity assessment in patients with large vessel vasculitis

PURPOSE OF REVIEW

The aim of this article was to review the recent contributions on the role of PET in assessing disease activity in patients with large-vessel vasculitis (giant cell arteritis and Takayasu arteritis).

RECENT FINDINGS

18 FDG (fluorodeoxyglucose) vascular uptake in large-vessel vasculitis at PET shows moderate correlation with clinical indices, laboratory markers and signs of arterial involvement at morphological imaging. Limited data may suggest that 18 FDG (fluorodeoxyglucose) vascular uptake could predict relapses and (in Takayasu arteritis) the development of new angiographic vascular lesions. PET appears to be in general sensitive to change after treatment.

SUMMARY

While the role of PET in diagnosis large-vessel vasculitis is established, its role in evaluating disease activity is less clear-cut. PET may be used as an ancillary technique, but a comprehensive assessment, including clinical, laboratory and morphological imaging is still required to monitor patients with large-vessel vasculitis over time.

Management of Takayasu arteritis

This review overviews the challenges in the assessment of disease activity, damage, and therapy of Takayasu arteritis (TAK). Recently developed disease activity scores for TAK are more useful for follow-up visits and require validation of cut-offs for active disease. A validated damage score for TAK is lacking. Computed tomography angiography (CTA), magnetic resonance angiography (MRA), and ultrasound enable the evaluation of vascular anatomy and arterial wall characteristics of TAK. 18-fluorodeoxyglucose (18-FDG) positron emission tomography (PET) visualizes arterial wall metabolic activity and complements the information provided by circulating C-reactive protein (CRP) levels. ESR and CRP alone moderately reflect TAK disease activity. TAK is corticosteroid-responsive but relapses upon tapering corticosteroids. Conventional synthetic disease-modifying anti-rheumatic drugs (DMARDs) are the first-line maintenance agents, and tumor necrosis factor-alpha inhibitors, tocilizumab, or tofacitinib are second-line agents for TAK. Revascularization procedures for TAK should be used judiciously during periods of inactive disease.

18-Fluorodeoxyglucose positron emission tomography/computed tomography for large vessel vasculitis in clinical practice

Diagnosis, prognostic assessment, and monitoring disease activity in patients with large vessel vasculitis (LVV) can be challenging. Early recognition of LVV and treatment adaptation is essential because vascular complications (aneurysm, dilatations, ischemic complications) or treatment related side effects can occur frequently in these patients. 18-fluorodeoxyglucose positron emission tomography/computed tomography (2-[18F]FDG-PET/CT) is increasingly used to diagnose, follow, and evaluate treatment response in LVV. In this review, we aimed to summarize the current evidence on the value of 2-[18F]FDG-PET/CT for diagnosis, follow, and treatment monitoring in LVV.

Outcome Measures and Biomarkers for Disease Assessment in Takayasu Arteritis

Takayasu arteritis (TAK) is a less common large vessel vasculitis where histopathology of involved arteries is difficult to access except during open surgical procedures. Assessment of disease activity in TAK, therefore, relies on surrogate measures. Clinical disease activity measures such as the National Institutes of Health (NIH) score, the Disease Extent Index in TAK (DEI.TAK) and the Indian TAK Clinical Activity Score (ITAS2010) inconsistently associate with acute phase reactants (APRs). Computerized tomographic angiography (CTA), magnetic resonance angiography (MRA), or color Doppler Ultrasound (CDUS) enables anatomical characterization of stenosis, dilatation, and vessel wall characteristics. Vascular wall uptake of 18-fluorodeoxyglucose or other ligands using positron emission tomography computerized tomography (PET-CT) helps assess metabolic activity, which reflects disease activity well in a subset of TAK with normal APRs. Angiographic scoring systems to quantitate the extent of vascular involvement in TAK have been developed recently. Erythrocyte sedimentation rate and C-reactive protein have a moderate performance in distinguishing active TAK. Numerous novel biomarkers are under evaluation in TAK. Limited literature suggests a better assessment of active disease by combining APRs, PET-CT, and circulating biomarkers. Validated damage indices and patient-reported outcome measures specific to TAK are lacking. Few biomarkers have been evaluated to reflect vascular damage in TAK and constitute important research agenda.

Advances in Takayasu arteritis: An Asia Pacific perspective

Takayasu Arteritis (TA) is a rare form of chronic granulomatous large vessel vasculitis that is more common in Asia compared to other parts of the world. There have been several developments in the field of Takayasu arteritis in relation to genetics, classification, clinical features, imaging, disease activity assessment and management and much of these works have been done in the Asia Pacific region. We will be discussing selected few in the current review.

Takayasu arteritis

PURPOSE OF REVIEW

The purpose of this review is to summarize the recent advances in Takayasu arteritis (TAK), mainly focusing on pathogenesis, imaging modalities, and management.

RECENT FINDINGS

Three novel clusters based on angiographic findings were identified in the Indian cohort and replicated in the North American cohorts. Different new imaging modalities have been tried in the assessment of arterial inflammation with promising results. There is more evidence on the long-term use of tocilizumab, but relapses are common. In light of the recent findings on the pathogenesis of TAK, Janus kinase inhibitors seem to be promising.

SUMMARY

Improvement in imaging modalities and in our understanding of the disease pathogenesis will allow us to better assess the disease activity and identify effective therapeutic agents.