New Perspectives on Diagnosing Psoriatic Arthritis by Imaging Techniques

Figures & data

Figure 1 Sacroiliitis on MRI. Coronal STIR (short tau inversion recovery) sequence shows extensive subchondral oedema involving the left sacroiliac joint, consistent with unilateral sacroiliitis in a patient with psoriasis.

Figure 2 Sacroiliitis on CT. Axial CT (computer tomography; left side of the figure) and T1-weighted sequence (right side of the figure) demonstrates subchondral sclerosis and erosions.

Figure 3 Aseptic spondylodiscitis. Sagittal T1-weighted and STIR sequences in a patient with longstanding psoriatic arthritis show disc oedema with subchondral bone marrow involvement at L2-L3 level, consistent with aseptic spondylodiscitis (Andersson lesion).

Table 1 Imaging Techniques in Psoriatic Arthritis

Ionizing Techniques		Advantages	Disadvantages
	CR	Detection of structural lesions Can be repeated for assessment of progression of the disease Low cost Available	Ionizing radiation Lack of information on soft tissue Lack of information on early stages of the disease
	CT	Detection of structural damage with high accuracy	High level of ionizing radiation Lack of information on soft tissue
	Low-dose CT	Detection of structural lesions with high accuracy Lower dose of radiation than conventional CT	Lower availability of the method Cost Lack of information on soft tissue
	PET/CT	Detection of whole body inflammation Gives a perspective of the extension of the disease	Lack of specificity for diagnosis Very high cost
Non Ionizing techniques	US	Rapid, painless and inexpensive Detection of synovitis, tenosynovitis, enthesitis, dactylitis with high accuracy Multiple sites can be scanned in one session Can be repeated as needed for follow-up Best tool for peripheral sites	No value for profound structures (spine, SI joints) Little information on structural damage Slow learning curve for musculoskeletal US
	MRI	Detection of inflammatory and structural lesions in profound or superficial sites Best tool for profound sites (spine, sacroiliac joints)	High Cost Low availability of the method
	Whole body MRI	Detection of whole body inflammation Gives a perspective of the extension of the disease (even subclinical)	Very high cost Little availability of the method
	Fluorescence optical imaging	Can detect increased vascularization associated with different type of inflammatory arthritis Can differentiate between types of arthritis (PsA, RA)	Little availability

Abbreviations: CR, conventional radiography; CT, computed tomography; PET/CT, High-resolution Positron Emission Tomography; US, ultrasound; MRI, magnetic resonance imaging; PsA, psoriatic arthritis; RA, rheumatoid arthritis.