The design of a sample rapid magnetic resonance imaging (MRI) acquisition protocol supporting assessment of multiple articular tissues and pathologies in knee osteoarthritis

Abstract

Objective: This expert opinion paper proposes a design for a state-of-the-art magnetic resonance image (MRI) acquisition protocol for knee osteoarthritis clinical trials in early and advanced disease. Semi-quantitative and quantitative imaging endpoints are supported, partly amendable to automated analysis. Several (peri-) articular tissues and pathologies are covered, including synovitis.

Method: A PubMed literature search was conducted, with focus on the past 5 years. Further, osteoarthritis imaging experts provided input. Specific MRI sequences, orientations, spatial resolutions and parameter settings were identified to align with study goals. We strived for implementation on standard clinical scanner hardware, with a net acquisition time ≤30 ​min.

Results: Short- and long-term longitudinal MRIs should be obtained at ≥1.5T, if possible without hardware changes during the study. We suggest a series of gradient- and spin-echo-sequences, supporting MOAKS, quantitative analysis of cartilage morphology and T2, and non-contrast-enhanced depiction of synovitis. These sequences should be properly aligned and positioned using localizer images. One of the sequences may be repeated in each participant (re-test), optimally at baseline and follow-up, to estimate within-study precision. All images should be checked for quality and protocol-adherence as soon as possible after acquisition. Alternative approaches are suggested that expand on the structural endpoints presented.

Conclusions: We aim to bridge the gap between technical MRI acquisition guides and the wealth of imaging literature, proposing a balance between image acquisition efficiency (time), safety, and technical/methodological diversity. This approach may entertain scientific innovation on tissue structure and composition assessment in clinical trials on disease modification of knee osteoarthritis.

Keywords: Clinical trial; Early- and late-stage disease; MRI acquisition protocol; Osteoarthritis (OA); Synovitis.

Fig. 1

Example images of the proposed sample MRI acquisition protocol for clinical trials. These encompass the 1st and 2nd echo of the qDESS MRI sequence with water excitation (we). The 1st echo displays a mixed T1/T2 contrast, whereas the second one exhibits T2 and diffusion weighted imaging contrast. The “clinical” sequences in three orientations include a sagittal (sag) PD weighted TSE sequence with fat-saturation (FS) as well as an axially orientated PD TSE FS; the coronal (Cor) TSE sequence is acquired with T1 weighting (T1) and without FS. Finally, an axial FLAIR is obtained with FS. The MRIs were obtained on a 3T Siemens VIDA scanner (Software Version Numaris VA 50).

Fig. 2

Standard (top) and high resolution (HR, bottom) axial localizer image for the double oblique coronal and sagittal acquisitions. Comparison of the localizer images demonstrates that the HR acquisition is superior in obtaining a double oblique coronal orientation (red line) pertinent to the DBEV, and in acquiring sagittal images perpendicular to the DBEV.

Fig. 3

Axial HR localizer images shown on the left with a red line displaying the position of the respective coronal MRI. The middle image on the right shows a coronal MRI positioned double oblique to obtain a double bull eyes view (DBEV). The superior image on the right shows a coronal MRI posterior, and the inferior image a coronal MRI anterior to the DBEV. The MRIs were obtained on a 3T Siemens VIDA scanner.