State University of Medicine and Pharmacy N. Testemitanu

State University of Medicine and PharmacyN. Testemitanu

Department of Radiology and Medical Imaging

MAGNETIC RESONANCE IMAGING OF THE OSTEOARTICULAR SYSTEM IN RHEUMATIC DISEASES

Elzhalka AfnanGroup 1646

Actuality Magnetic resonance imaging (MRI) has important applications in musculoskeletal medicine. It allows the visualization of the bone and soft tissues in three dimensions using a multiplanar technique and is uniquely suited for joint imaging, mainly the metacarpo-phalangeal joints (MCP) and the carpal joints affected in the rheumatoid arthritis (RA). Rheumatoid Arthritis (RA) is a chronic systemic inflammatory disease of unknown etiology. the response to an autoimmune reactions leads to synovial hypertrophy and chronic joint inflammation with the potential of extraarticular manifestationsEpidemiological data: RA affects 0.5-1% of adult population worldwide, it occurs more frequently in females than in males with a 3:1 ratio

Aims and objectivesThe aims are to carry out the importance of the MRI in the assessment of RA, and showing how MRI has demonstrated greater sensitivity for the detection and quantification of the main radiological findings on which early diagnosis of RA is based( bone erosions, synovitis, and bone marrow edema). The objectives : the most important early changes detected by MRI observed in patients with RA the most frequently involved bones which demonstrate the early pathologic changes in RA

MRI TechniqueThe MRI can show different types of pathologies. There are two basic sequences in the MRI which are known as the T1-weighted and T2-weighted sequences. The T1-weighted images demonstrate water as hypointense(dark), and fat as hyperintense(bright). When thw T2-weighted images water is represented as hyperintense and fat as hypointense.The OMERACT group recommends starting in the diagnosis with a coronal STIR(short inversion time inversion recovery) sequence or a fat saturated T2 sequence on the wrist and MCP joints for bone marrow edema detection, followed by T1 sequence on the coronal and axial plane before and after gadolinium contrast for detection of bone erosions and synovitisMain pattern of MRI in RA CharacteristicsSpecifications Joints regions examined Wrist and second through fifth MCP unilateral (dominant hand or the most painful)MRI damage signsEdema, synovitis, erosionsEquipment-magnetic typeMagnetic field recommendation is 1.5 TeslaContrast Gadolinium Sequence Coronal T1, axial T1, coronal T2 with fat saturation, contrast enhanced axial and coronal T1 with fat saturation Monitoring response scoreOMERACT/RAMRIS ,synovium volume measurement, scoring contrast-enhanced dynamicMRI FindingsSynovitis: is the earliest abnormality to appear in RA,in which the thickening of synovial tissue caused by the rheumatoid inflammatory process may be identified on MRI. Synovitis has an intermediate to low signal intensity on T1-weighted images and due to the increased water content has high signal intensity on T2-weighted images.

MRI signs of synovitis include: 1. increased synovial volume 2.increased water content 3. contrast-enhancement(increased signal intensity after the intravenous injection of gadolinium).Synovitis in early RA of the wrist (eight months duration) and normal radiographic finding. (A) Coronal T1-weighted MRI shows radio carpal synovitis as low signal intensity (arrow). (B)Coronal gadolinium-enhanced fat suppressed T1-weighted MRI shows intense enhancement of the radio carpal synovitis.

abTomografia prin rezonana magnetic a regiunii carpiene i metacarpo-falangiene: manifestri de sinovit nu se constat. A-C executate n poziia coronarian T1 timp de relaxare longitudinal, spin-spin articulaiilor metacarpofalangiene lipsesc arii densificate ce ar vorbi despre sinovita n articulaiile respective.

MRI FindingsBone marrow edema: although bone marrow edema is nonspecific and has been well documented in traumatic, and degenerative bone processes, it is reported to be an important MRI finding in patients with RA, especially in the earlier phases. Bone marrow edema manifested as ill-defined signal intensity changes in bone marrow, with high signal intensity on fat-suppressed T2-weighted sequences and increased signal intensity after the administration of gadolinium-based contrast. The OMERACT defines BOM at MR imaging as a lesion within the trabecular bone with an ill-defined margins and signal characteristics of increased water content. The bone marrow edema is usually located in the subchondral bone(MCP, PIP joints)

Bone marrow edema in early rheumatoid arthritis of the wrist (6 months duration) and normal radiographic findings. (a, b) Coronal unenhanced (a) and gadolinium-enhanced fat-suppressed (b) T1-weighted MR images show bone marrow edema changes at the base of the first metacarpal bone (*), a finding that is better identified in b. There is a markedly enhanced erosion (large arrow) of the pisiform bone. The pisotriquetral joint recess is occupied by synovitis and fluid (small arrows), which are enhanced in b. (c, d) Axial unenhanced (c) and contrast-enhanced fat-suppressed (d) T1-weighted MR images show extensive dorsal wrist synovitis (*). Note that the erosion ofthe pisiform bone is also seen in this plane, as well as other more lateral erosions (arrows).10MRI FindingsBone Erosions: the detection of erosions at MRI is important for diagnosis and prognosis in patients with RA. MRI provides an early diagnosis of RA by revealing erosions, whose presence constitutes one of the ACR 1987 diagnostic criteria. The MRI definition of erosion on T1-weighted images are:1. loss of normal low signal intensity of cortical bone and 2. loss of normal high signal intensity of the bone marrow cavity, with enhancement after administration of gadolinium and 3. as high signal intensity on T2-weighted images. The erosions indicate irreversible joint damage.Early erosions start in the cartilaginous void of the joint as a result of synovial proliferation-synovitis (mostly in MCP) indicates the progression to erosion.Erosions early rheumatoid arthritis of the wrist (1year duration) and normal radiographic findings. (a) Coronal contrast-enhanced fat-suppressed T1-weighted MR image shows erosion of the base of the second metacarpal bone (arrow), with cortical discontinuity and enhancement. Synovitis at the dorsal region of the wrist is also seen (*). (b) Axial contrast-enhanced fat-suppressed T1-weighted MR image shows the erosion of the base of the second metacarpal bone, as well as other small erosions of the base of the third metacarpal bone (arrows). Synovitis is seen about the flexor tendons and the bases of the metacarpal bones

The most frequently bones involved in RA disease processStudies show that MRI of unilateral wrist and 2nd-5th metacarpophalangeal(MCP) joints is more sensitive to change for erosive progression in early and established RA.In the following study the MRI datasets from 258 RA patients(126 with early RA disease duration