Optimization and validation of a rapid high-resolution T1-w 3D FLASH water excitation MRI sequence for the quantitative assessment of articular cartilage volume and thickness
Introduction
Osteoarthritis has a considerable clinical, social and economical impact [1], [2], [3]. As damage to the articular cartilage is a decisive factor in its pathogenesis [4], [5], the extent of cartilage damage is more and more accepted as a criterion for therapeutic decisions and new therapeutic concepts are being developed [6], [7], [8]. Consequently, there is a strong need for an easy accessible, non-invasive, accurate and reliable assessment of cartilage and MRI is considered well suited [9], [10], [11], [12], [13], [14], [15] for these demands. T1-weighted (T1-w) 3D gradient echo (GRE) sequences with spectral fat suppression (FS) have yielded good results concerning lesion detection, but correct evaluation of small focal cartilage defects is still subject to discussion [11], [16], [17], [18] and 2changes in signal intensity are not sufficiently understood due to the complex composition of articular cartilage [16], [19], [20], [21], [22], [23], [24]. Cartilage volume and thickness, however, constitute simple, global parameters to assess the long-term degradation of cartilage and its recovery. Measurement of cartilage volume and thickness has been shown to be reproducible and valid, if high resolution 3D T1-w FS GRE sequences and adequate 3D postprocessing [25], [26], [27], [28], [29], [30], [31] are applied.
However, the long imaging times of these GRE sequences have prevented a widespread routine clinical application of the technique. Imaging times range from 10′18″ to 13′30″ [17], [32] at 0.6 × 0.6 mm2, and up to 16′30″ and even 21′[17], [18], [25], [26] at 0.3 × 0.3 mm2 in plane resolution. Yet, imaging time should be kept as short as possible, especially with respect to the patients’ comfort and acceptance of the MRI-examination.
Application of selective water excitation instead of frequency selective fat presaturation has been shown [33] to shorten the acquisition time and to produce stable fat suppression. Therefore, the objective of this study was to generate a rapid cartilage dedicated high resolution T1-w 3D FLASH sequence using water excitation instead of conventional spectral fat suppression. This sequence was then adapted for cartilage visualization by optimizing its flip angle and was validated for quantification of cartilage volume and thickness.
Section snippets
Material and methods
We analyzed the cartilage of the right knees of nine healthy volunteers without any history of musculoskeletal affection or previous knee injury. Their age ranged from 22 to 68 (mean 31) years. As cartilage volume and thickness are prone to changes after physical exercise [34], the volunteers were asked to rest for 1 hour in a supine position in order to completely unload the knee before data acquisition.
The examinations were performed in a 1.5 T Magnet (Magnetom Vision, Siemens/Erlangen,
Optimization of the flip angle
The S/N ratios for cartilage, subchondral bone, fat and menisci increased with increasing FA. S/N for muscle decreased at FA’s > 30°. The S/N ratios for fat were in the same order of magnitude in FS and WE sequence. The S/N for cartilage in the WE sequence (FA 30°) was about 75% of S/N in the FS sequence. The values of S/N and C/N for cartilage vs subchondral bone, menisci, fat and muscle are shown in Fig. 1 (a,b). The C/N ratios for cartilage versus subchondral bone, fat, menisci and muscle
Discussion
The purpose of this study was to optimize a high resolution 3D FLASH sequence for visualization of the articular cartilage with a special focus on short acquisition time, and to validate the sequence for quantitative cartilage volume and thickness measurements.
In clinical routine, especially in terms of patients’ tolerance, a compromise has to be found between anatomical resolution, image contrast and acquisition time. Because high contrast between cartilage and surrounding tissues is a main
Acknowledgements
This study was in part supported by the Deutsche Forschungsgemeinschaft (DFG).
References (46)
- et al.
Mechanical determinants of osteoarthrosis
Sem Arthritis Rheum
(1991) - et al.
Emerging applications of magnetic resonance imaging in the evaluation of articular cartilage
Radiol Clin North Am
(1996) - et al.
High resolution MRI of small jointsimpact of spatiol resolution on diagnostic performance and SNR
Magn Reson Imaging
(1998) - et al.
A non-invasive technique for 3-dimensional assessment of articular cartilage thickness based on MRI. Part I: development of a computational method
Magn Reson Imaging
(1997) - et al.
A non-invasive technique for 3-dimensional assessment of articular cartilage thickness based on MRI. Part 2: Validation based on CT arthrography
Magn Reson Imaging
(1997) - et al.
Non-invasive determination of cartilage thickness throughout joint surfaces using magnetic resonance imaging
J Biomechanics
(1997) - et al.
Indirect and nonmedical costs among people with rheumatoid arthritis and osteoarthritis compared with nonarthritic controls
J Rheumatol
(1997) - et al.
The economic cost and social and psychological impact of musculoskeletal conditions
Arthritis Rheum
(1995) - et al.
Costs attributable to osteoarthritis
J Rheumatol
(1998) Problems and paradigms in joint pathology
J Anat
(1994)
Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation
N Engl J Med
Current treatment options for the restoration of articular cartilage
Am J Knee Surg
Exercise protects against articular cartilage degeneration in the hamster
Arthritis Rheum
Osteoarthritis of the knee, comparison of radiography, CT and MR imaging to assess extent and severity
Am J Roentgenology
Relationship between arthroscopic evidence of cartilage damage and radiographic evidence of joint space narrowing in early osteoarthritis of the knee
Arthritis Rheum
Magnetic resonance imaging of normal and ostoarthritic cartilage
Arthritis Rheum
MR imaging of cartilage
Radiology
MR imaging of the arthritic kneeimproved discrimination of cartilage, synovium and effusion with pulsed saturation transfer and fat suppressed T1-weighted sequences
Radiology
MR imaging of articular cartilagecurrent status and future directions
Am J Roentgenol
Short echo time projection reconstruction MR imaging of cartilagecomparison with fat-suppressed spoiled GRASS and magnetisation transfer contrast MR imaging
Radiology
Accuracy of fat-suppressed three-dimensional spoiled gradient-echo FLASH MR Imaging in the detection of patellofemoral articular cartilage abnormalities
Radiology
Severity of articular cartilage abnormality in patients with osteorthritisevaluation with fast spin-echo MR vs arthroscopy
Am J Roentgenol
Articular cartilage in the kneemapping of the physiologic parameters at MR imaging with a local gradient coil—preliminary results
Radiology
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