Feasibility of US-CT image fusion to identify the sources of abnormal vascularization in posterior sacroiliac joints of ankylosing spondylitis patients

Use of Multimodality Imaging in the Evaluation of Patients With Spondyloarthropathies and Sacroiliitis

Spondyloarthropathy (SpA) is one of the most common causes of low back pain. It is caused by inflammatory arthritis in the spine, manifesting in various forms such as psoriatic arthritis (PsA), ankylosing spondylitis (AS), and sacroiliitis. A comprehensive systematic literature search was done to evaluate and compare MRI, CT, single-photon emission CT, PET, ultrasound (US) imaging, low-dose CT, and diffusion-weighted imaging (DWI) techniques in assessing SpAs. The search strategy was constructed by an analysis of key terms from relevant articles in MEDLINE ProQuest, Embase, and PubMed. The key terms used to search for these articles were "SpA," "sacroiliitis," "spondylitis," "psoriatic arthritis," "MRI," "CT scan," "x-ray," "magnetic resonance imaging," "computed tomography," "bone density," and "ultrasound." A total of 1,131 articles published in English between January 1, 2003, and October 15, 2023 were identified and screened for eligibility by members of the research team, which resulted in 69 total articles selected for the final review. US has played an important role in visualizing joint inflammation and enthesitis (inflammation of the enthesis), which are common features of PsA. Although MRI and CT are considered more reliable modalities for diagnosing active sacroiliitis, US imaging with Doppler flow can also be useful in conjunction with CT images to visualize abnormal blood flow in the sacroiliac joints, as well as other joints affected by inflammatory arthritis. MRI provides increased diagnostic confidence in the diagnosis of sacroiliitis in active AS patients when compared to CT. CT is more sensitive than plain radiographs. The PET activity score showed a good correlation in diagnosing inflammatory sacroiliitis but lacked in identifying structural lesions. CT has high diagnostic accuracy, but it exposes patients to a high radiation dose. MRI visualizes joint and tissue inflammation, bone, and bone marrow change and can identify peripheral inflammation in soft tissue and joints in patients diagnosed with PsA. MRI can also visualize bone marrow changes and subchondral edema, which can aid in the early diagnosis of ankylosing SpA and gauge disease severity. DWI and short-tau inversion recovery imaging are both MRI techniques used in detecting sacroiliitis. MRI and CT are shown to be reliable imaging modalities for the diagnosis of sacroiliitis; however, it was found that Doppler US played an accurate role in the diagnosis as well. MRI visualizes joints and tissue with the most precision, making it useful in evaluating patients with PsA, while PET CT is useful in the diagnosis of inflammatory sacroiliitis patients. There is limited literature available comparing the multiple modalities of imaging available for each SpA. The review's objective is to analyze imaging findings in patients diagnosed with sacroiliitis and SpAs. The findings in this literature review are valuable for properly assessing and diagnosing patients suffering from SpAs.

Doppler and Spectral Ultrasound of Sacroiliac Joints in Pediatric Patients with Suspected Juvenile Spondyloarthritis

Background: Power Doppler ultrasound (PDUS) with spectral wave analysis (SWA) has been compared with magnetic resonance imaging (MRI) in documenting active sacroiliitis in early spondyloarthritis (SpA) but, to date, PDUS/SWA has not been yet applied to the study of sacroiliac joints (SIJs) in children. Methods: A group of 20 children (13 F/7 M, mean age 14.2 y) with suspected juvenile SpA (jSpA) underwent PDUS/SWA and, subsequently, MRI of the SIJs. SIJs PDUS scoring and resistance index (RI) of the SIJs flows were recorded. The accuracy of PDUS/SWA for the diagnosis of active sacroiliitis was evaluated, with MRI as the gold standard. Results: PDUS signals were detected in 19 patients and 30 SIJs. Bone marrow edema (BME) lesions on MRI were detected in 12 patients (diagnosed as jSpA) and 22 SIJs. PDUS scoring on SIJs were higher in patients with a final diagnosis of jSpA (p = 0.003). On SWA, the mean RIs in patients with or without final diagnosis of active sacroiliitis were, respectively, 0.604 and 0.767 (p = 0.005) at joint level. A RI < 0.55 and PDUS > 1 showed the higher specificity for sacroiliitis (AUROC curve 0.854 for PDUS and 0.920 for RI). SIJs PDUS/SWA showed an overall concordance of 82.35%, with substantial agreement (k = 0.627) with MRI on the diagnosis of sacroiliitis. Conclusions: In children with sacroiliitis, PDUS demonstrates a rich vascularization into SIJs and low RIs (<0.55) have high specificity for this condition. SIJs PDUS/SWA could be useful as a screening method in children with suspected jSpA.

Power and spectral Doppler ultrasound in suspected active sacroiliitis: a comparison with magnetic resonance imaging as gold standard

OBJECTIVES

The objectives of this study were to study with Power Doppler US (PDUS) the SI joints (SIJs) of patients with suspected active sacroiliitis, to describe SIJ flows with spectral wave analysis (SWA) on Doppler US, and to correlate US data with both clinical characteristics and presence of SIJ bone marrow oedema (BME) in subsequent MRI.

METHODS

A total of 42 patients (32 females and 10 males, mean age 46.8 years) with recent onset of inflammatory back pain (IBP) were included. Every patient underwent US examination with a convex 1-8 MHz probe [scoring PDUS signals with a three-point scale and describing flows in SWA calculating the mean Resistive Index (RI)] and subsequent MRI of the SIJs.

RESULTS

PDUS signals were detected in 34 patients and 62 SIJs. In 29 patients and 56 SIJs, MRI revealed BME. A definite diagnosis of SpA was made in 32 patients. PDUS signals were more frequent (P < 0.0001) in patients with a final diagnosis of SpA, yielding a higher PDUS score (P = 0.0304). PDUS grading correlated with both BME grading (r = 0.740, P = 0.0001) and AS DAS (ASDAS) (r = 0.6257, P = 0.0004), but not with inflammatory reactants nor anthropometric data. Mean RI were, respectively, 0.60 and 0.73 (P < 0.0001) in patients with or without diagnosis of active sacroiliitis. The most inclusive RI cut-off resulted <0.70 [positive predictive value (PPV) 94%, accuracy 90%, P = 0.0001]. The best Likelihood Ratio (5.471) for RI to detect pathologic cases was obtained with a cut-off of <0.60 (PPV 96%).

CONCLUSIONS

PDUS and SWA of SIJs demonstrate good diagnostic accuracy for active sacroiliitis compared with MRI.

The Potential Use of Ultrasound-Magnetic Resonance Imaging Fusion Applications in Musculoskeletal Intervention

We sought to assess the potential use of an application allowing real-time ultrasound spatial registration with previously acquired magnetic resonance imaging in musculoskeletal procedures. The ultrasound fusion application was used to perform a range of outpatient procedures including piriformis, sacroiliac joint, pudendal and intercostal nerve perineurial injections, hamstring-origin calcific tendonopathy barbotage, and 2 soft tissue biopsies at our institution in 2015. The application was used in a total of 7 procedures in 7 patients, all of which were technically successful. The ages of patients ranged from 19 to 86 years. Particular use of the fusion application compared to sonography alone was noted in the biopsy of certain soft tissue lesions and in perineurial therapeutic injections.