BackgroundDWI has been proposed for SpA diagnosis and disease monitoring1,2. The clinical correlation and effectiveness of this imaging when compared to the traditional STIR sequence is still under evaluation.ObjectivesTo compare DWI with with clinical features, and traditional STIR sequence in detecting spinal and SI joints inflamation in SpA patients.MethodsOne hundred and ten patients fulfilled ASAS Axial SpA criteria were recruited consecutively from two rheumatology centers in Hong Kong. Clinical, radiological and blood parameters were collected. DWI and STIR MRI were performed simultaneously and results were scored according to the Spondyloarthritis Research Consortium of Canada (SPARCC) for comparison. The Apparent Diffusion Coefficient (ADC) values were also calculated.ResultsDWI showed no correlation with clinical features. When compare with STIR sequence, it correlated well with STIR sequence at the SI joints level (CC 0.76, p<0.001), but weakly at the spinal level (CC 0.23, p=0.02). At SI joints level, presence of inflammation by both STIR sequence and DWI were associated with increase in maximum (B=0.24, p=0.02 in STIR; B=0.37, p<0.001 in DWI) and mean ADC values (B=0.17, p=0.003 in STIR; B=0.15, p=0.01 in DWI). Maximum (B=0.19, p=0.04) and mean spinal ADC values (B=0.18, p=0.01) were also positively associated with DWI detected spinal inflammation. STIR sequence had no association with ADC values. Presenec of Modic lesion showed positive correlation with STIR (B=7.12, p=0.01) but not spinal ADC values.ConclusionsBoth STIR sequence and DWI perform similiarily in detecting active sacroiliitis. At spinal level, ADC values appear to be independent of other imaging/ clinical assessment and are not affected by degenerations.ReferencesGaspersic N, Sersa I, Jevtic V, et al. Monitoring ankylosing spondylitis therapy by dynamic contrast-enhanced and diffusion-weighted magnetic resonance imaging. Skeletal Radiol. 2008 Feb; 37(2): 123–31.Sahin N, Hacibeyoglu H, Ince O, et al. Is there a role for DWI in the diagnosis of sacroiliitis based on ASAS criteria? Int J Clin Exp Med. 2015 May 15; 8(5): 7544–52.Disclosure of InterestNone declared

Abstract. Detailed descriptions of cardiac geometry and architecture are necessary for examining and understanding structural changes to the myocardium that are the result of pathologies, for interpreting the results of experimental studies of propagation, and for use as a three-dimensional orthotropically anisotropic model for the computational reconstruction of propagation during arrhythmias. Diffusion tensor imaging (DTI) provides a means to reconstruct fibre and sheet orientation throughout the ventricles. We reconstruct and quantify canine cardiac architecture in selected regions of the left and right ventricular free walls and the inter-ventricular septum. Fibre inclination angle rotates smoothly through the wall in all regions, from positive in the endocardium to negative in the epicardium. However, fibre transverse and sheet angles show large variability in basal regions. Additionally, regions where two populations (positive and negative) of sheet structure merge are identified. From these data, we conclude that a single DTI-derived atlas model of ventricular architecture should be applicable to modelling propagation in wedges from the equatorial and apical left ventricle, and allow comparisons to experimental studies carried out in wedge preparations. However, due to inter-individual variability in basal regions, a library of individual DTI models of basal wedges or of the whole ventricles will be required.