High-resolution interleaved water-fat MR imaging of finger joints with chemical-shift elimination

A Comparative Study of High-Resolution Chemical-Shift-Eliminated Magnetic Resonance Imaging of Finger Specimens with Microcomputed Tomography

Objective:

High-resolution images of finger joints with chemical-shift elimination can be obtained using an interleaved water-fat (IWF) sequence. This study assessed IWF imaging of finger joints in the delineation of bone structures by comparing images of cadaver fingers with those of microcomputed tomography (CT) that served as a standard reference.

Materials and Methods:

IWF images with spatial resolution of 176 µ × 176 µ × 300 µ were obtained from the distal and proximal interphalangeal joints of two cadaver finger specimens using a custom-built radiofrequency receive coil at 1.5T. Regular three-dimensional gradient-echo (GRE) images were also acquired with similar parameters and compared with the IWF images to evaluate the effects of chemical shift. Micro-CT scans were obtained and served as the standard reference. The image data were reviewed by two experienced musculoskeletal radiologists in consensus. The delineation of normal joint structures and abnormalities in the finger specimens as revealed by the magnetic resonance imaging (MRI) and micro-CT images were compared. The IWF and regular GRE images were assigned scores 0–3 for the depiction of apparent marginal bone defects, with zero being the same in appearance to the micro-CT image and three as having minimal resemblance to it. Statistical analysis of the scoring results was conducted to compare the two MRI techniques.

Results:

The high-resolution IWF images provided accurate delineation of bone and calcified structures as seen in micro-CT. The thickness of subchondral bone was depicted similarly on the IWF water + fat and the micro-CT images but not on the regular GRE images. The regular GRE sequence showed false marginal bone defects not observed with IWF and micro-CT. In addition, the IWF water-only images facilitated the identification of bone cyst by revealing its water content.

Conclusion:

High-resolution IWF imaging should be useful for the early diagnosis and treatment assessment of arthritis and should also benefit basic research in the pathophysiology of the disease.

Clinical applications of advanced magnetic resonance imaging techniques for arthritis evaluation

Magnetic resonance imaging (MRI) has allowed a comprehensive evaluation of articular disease, increasing the detection of early cartilage involvement, bone erosions, and edema in soft tissue and bone marrow compared to other imaging techniques. In the era of functional imaging, new advanced MRI sequences are being successfully applied for articular evaluation in cases of inflammatory, infectious, and degenerative arthropathies. Diffusion weighted imaging, new fat suppression techniques such as DIXON, dynamic contrast enhanced-MRI, and specific T2 mapping cartilage sequences allow a better understanding of the physiopathological processes that underlie these different arthropathies. They provide valuable quantitative information that aids in their differentiation and can be used as potential biomarkers of articular disease course and treatment response.

Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) of the wrist and finger at 3T: comparison with chemical shift selective fat suppression images

PURPOSE

To compare fat-suppressed magnetic resonance imaging (MRI) quality using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with that using chemical shift selective fat-suppressed T1-weighted spin-echo (CHESS) images for evaluating rheumatoid arthritis (RA) lesions of the hand and finger at 3T.

MATERIALS AND METHODS

MRI was performed in eight healthy volunteers and eight RA patients with a 3.0T MR system (Signa HDxt GE healthcare) using an eight-channel knee coil. FS-CHESS-T1-SE and IDEAL imaging were acquired in the coronal planes covering the entire structure of the bilateral hands with a slice thickness of 2 mm. In the RA patients both images were obtained after intravenous gadolinium administration. Image quality was evaluated on a five-point scale (1 = excellent to 5 = very poor). Synovitis and bone marrow contrast uptake on MR images were reviewed by two musculoskeletal radiologists using the Rheumatoid Arthritis MRI Scoring System (RAMRIS) of the Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) group.

RESULTS

IDEAL showed uniform FS unaffected by magnetic field inhomogeneity and challenging geometry of hand and fingers, while CHESS-T1-SE often showed FS failure within the first metacarpal joint, tip of the finger, and ulnar aspect of the wrist joint. Overall image quality was significantly better with IDEAL than CHESS-T1-SE images (4.43 vs. 3.43, P < 0.01). Interobserver agreement (κ value) for synovitis and bone marrow contrast uptake was good to excellent with IDEAL (0.74-0.91, 0.62-0.89, respectively).

CONCLUSION

IDEAL could compensate for the effects of field inhomogeneities, providing uniform FS of the hand and finger than did the CHESS-T1-SE sequence.