AB1204 COMPARISON OF DIAGNOSTIC SIGNIFICANCE OF HIGH RESOLUTION COMPUTED TOMOGRAPHY (HRCT) AND MAGNET RESONANCE IMAGING (MRI) IN SYSTEMIC SCLEROSIS INTERSTITIAL LUNG DISEASE (SSc-ILD) – A PROSPECTIVE BLINDED MONO-CENTRE STUDY OF 20 CASES
Authors: G. Assmann, M. Schmidt, M. Ramona, T. Ryszard, G. Finn Markus, S. Iram, M. Christoph
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Lung involvement with ILD is extremely relevant for the prognosis for systemic sclerosis (SSc). In addition to pulmonary function testing including the determination of diffusion capacity, lung imaging is the decisive diagnostic tool for determining the indication for treatment and the course of the disease. High resolution computed tomography (HRCT) is the established standard of imaging in SSc-ILD, magnet resonance imaging (MRI) is an alternative tool, but with reduced informative value, however with optimal radiation hygiene. <h3>Objectives:</h3> To compare the findings of HRCT and MRI of the lung in SSc-ILD with regard to (1) the degree of interstitial fibrosis, (2) the extent of alveolitis/ground glass opacities, (3) fibrosis of the pleura and (4) the percentage manifestation of ILD in the pulmonary parenchyma. <h3>Methods:</h3> We conducted a prospective blinded controlled study of 20 SSc-ILD cases at the RUB University Hospital Minden, Germany, to compare the findings of HRCT and MRI of the lung (patients`characteristics in Table 1). All patients fulfilled the classification criteria of SSc according to the latest ACR/EULAR recommendation as previously published, ILD was diagnosed in all cases in the conference of an ILD board together with radiologists, rheumatologists and pulmonologists. All patients underwent HRCT and MRI of the lungs (maximum 7 days apart), HRCT was performed by high-resolution photoncounting HRCT (Siemens Naeotom, Siemens Healthcare, Erlangen); MRI use 3D ultrashort-echo-time (UTE) MR sequence technique in free breathing in 0.55 Tesla low-field MRI (Magnetom Free.Max, Siemens Healthcare, Erlangen, Germany). All HRCT images were evaluated by radiologists with high expertise in ILD diagnostics without knowledge of the respective MRI images and vice versa; the procedure was repeated three times by a total of three different radiologists. The evaluation matrix comprised four uniform gradings of (1) interstitial fibrosis, (2) alveolitis/ground glass opacities, (3) pleural thickening and (4) the percentage manifestation of ILD in general. The correlation (according to Pearson and Spearman) between the HRCT and MRI findings (n=60, respectively) was determined using SPSS, a p-value&lt;0.05 was assessed as significant. The interrater-investigator variability (between the three radiologists) was evaluated according to Fleiss kappa modality. The study was approved by the local ethics committee HDZ Bad Oeyenhausen, all patients gave their informed consent before they were included in the study. <h3>Results:</h3> The evaluations showed a relatively high agreement in the categories interstitial fibrosis degree (Pearson correlation 0.829) and gradual expression of ILD quantitatively (0.753), lower for alveolitis and pleural thickening (Figure 1). The results in all four categories had in common that the MRI mostly underestimated the severity due to the evaluation matrix. The interrater variability was surprisingly high (kappa: 0.99, 0.74, 0.56, 0.94) according to evaluation matrix, respectively). <h3>Conclusion:</h3> The study shows acceptable correlation of the HRCT findings with the MRI findings, particularly with regard to the degree of fibrosis in SSc-ILD, although the MRI findings have been significantly underestimated in comparison with HRCT. In our opinion, it is essential to specify the evaluation software for MRI optimizing the imaging of the special features of the lung parenchyma; further prospective studies to improve the MRI modalities are recommended before a broader use of MRI in SSc-ILD might be proposed. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> Gunter Assmann Boehringer-Inglheim, Vifor Pharma, AbbVie, UCP, Astrazeneca, Novartis, Michael Schmidt: None declared, Muecke Ramona: None declared, Turkiewicz Ryszard Boehringer Inglheim, MSD, Astrazeneca, AbbVie, Gellrich Finn Markus: None declared, Shahzadi Iram: None declared, Moenninghoff Christoph: None declared.