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Articular Cartilage Defects Detected with 3D Water-Excitation True FISP: Prospective Comparison with Sequences Commonly Used for Knee Imaging¹

¹ From the Departments of Radiology (S.R.D., C.W.A.P., M.R.S., M.Z., J.H.) and Orthopedic Surgery (P.P.K., F.K.), University Hospital, Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland. Received June 21, 2006; revision requested August 23; revision received October 26; accepted November 21; final version accepted April 2, 2007. Address correspondence to S.R.D. (e-mail: sylvain.duc{at}hcuge.ch).

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE IMPLICATION FOR PATIENT CARE References

 
Purpose: To prospectively compare the accuracy of three-dimensional (3D) water-excitation (WE) true fast imaging with steady-state precession (FISP) in the diagnosis of articular cartilage defects with that of sequences commonly used to image the knee, with arthroscopy or surgery as the reference standard.

Materials and Methods: This study protocol was institutional review board approved. Written informed consent was obtained from all patients. Thirty knees in 29 patients (mean age, 56 years; range, 18–86 years) were prospectively evaluated by using sagittal 3D WE true FISP with two section thicknesses (1.7 mm [true FISP_thin] and 3.0 mm [true FISP_thick]), two-dimensional (2D) intermediate-weighted spin-echo with fat saturation, 2D fast short inversion time inversion-recovery, 3D WE double-echo steady-state, and 3D fat-saturated fast low-angle shot sequences. Cartilage defects were graded on magnetic resonance images and during surgery with a modified Noyes scoring system. Contrast-to-noise ratio (CNR) and CNR efficiency were calculated. Sensitivity, specificity, and accuracy were assessed. Interobserver agreement was determined with statistics, and quantitative results were evaluated with the Wilcoxon signed rank test.

Results: The performance of 3D WE true FISP_thick (sensitivity, specificity, and accuracy, respectively, were 52%, 93%, and 71% for reader 1 and 65%, 88%, and 76% for reader 2) and 3D WE true FISP_thin (sensitivity, specificity, and accuracy, respectively, were 58%, 94%, and 75% for reader 1 and 63%, 80%, and 71% for reader 2) sequences was no different than that of other sequences in the detection of circumscribed defects. Three-dimensional WE true FISP sequences had a significantly (P < .0033) higher CNR and CNR efficiency between cartilage and fluid than the corresponding sequences with the same section thickness.

Conclusion: Three-dimensional WE true FISP enables high contrast between joint fluid and articular cartilage and a diagnostic performance that is comparable with that of standard sequences.

© RSNA, 2007

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE IMPLICATION FOR PATIENT CARE References

 
Research on magnetic resonance (MR) imaging of cartilage has recently concentrated on postoperative (1,2) imaging, determination of cartilage volume (3), and sequences most useful for detection of early cartilage damage, including T2 relaxation time mapping (4,5), diffusion mapping (6), and contrast material-enhanced imaging (delayed gadolinium-enhanced MR imaging of the cartilage, or dGEMRIC) (7–9).

For treatment planning, knowledge of the diagnosis and the extent of cartilage defects is important. Several sequences that are potentially useful for such assessment have been introduced, including the multiple-echo data image combination, or MEDIC, sequence (10,11) and the double-echo steady-state (DESS) sequence with or without water excitation (WE) (12). More recently, WE true fast imaging with steady-state precession (FISP) with a comparably short acquisition time has been introduced. The performance of research sequences in the detection of cartilage defects in comparison with that of standard MR sequences has, to our knowledge, not been assessed prospectively with an arthroscopic reference standard. Thus, the purpose of our study was to prospectively compare the accuracy of three-dimensional (3D) WE true FISP in the diagnosis of articular cartilage defects with that of sequences commonly used to image the knee, with arthroscopy or surgery as the reference standard.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE IMPLICATION FOR PATIENT CARE References

 
Patients
The study protocol was approved by the institutional review board of the Kanton of Zurich, Subcommittee for Orthopedics/Musculoskeletal System. Written informed consent was obtained from all patients. The consent form clearly stated that MR images obtained in our study would be evaluated after surgery.

A total of 30 knees in 29 patients (12 men, 17 women; mean age, 56 years; range, 18–86 years) were prospectively included in a consecutive fashion between February and July 2005. All patients underwent complete clinical work-up, including necessary diagnostic imaging, before surgery. Patients were included if they were at least 18 years old and were referred either for arthroscopy (n = 20) or open surgery (n = 9) of the knee. Patients were excluded if they had undergone prior knee surgery, if they had contraindications to MR imaging, or if cartilage could not be evaluated at surgery. During the inclusion period, surgery was performed in 303 knees. Seventeen interventions were performed in patients younger than 18 years. In the remaining 286 knees, arthroscopy or open surgery enabled complete inspection of articular cartilage in 260, and a surgical procedure in which cartilage was not seen completely was performed in 26. In 103 of the 260 remaining knees, surgery had been performed previously; thus, these knees were excluded from the study. For 30 of the 157 knees in which prior surgery had not been performed (Fig 1), the MR imager was available on short notice (within the short interval between final scheduling for surgery and the surgical procedure). The MR examinations were performed before surgery (mean interval between MR imaging and surgery, 1 day; range, 0–9 days).

View larger version (10K): [in this window] [in a new window] [Download PPT slide]   Figure 1: Flow diagram of patients.

Sagittal MR images were acquired with 3D WE true FISP, two-dimensional (2D) intermediate-weighted spin-echo with fat saturation, 2D fast short inversion time inversion-recovery (STIR), 3D WE DESS, and 3D fat-saturated fast low angle shot (FLASH) sequences. The sagittal plane was chosen because it enables all articular surfaces of the knee to be evaluated at once, with little partial volume effect in any of the surfaces. The 3D WE true FISP images were acquired with two section thicknesses adapted to those of the other sequences included in this study: The 3D WE true FISP_thin images were acquired with a section thickness of 1.7 mm, and the 3D WE true FISP_thick images were acquired with a section thickness of 3.0 mm. Pixel size and field of view were identical for all sequences. A turbo factor of seven was used for both 2D sequences. The other parameters were based on manufacturer suggestions but were adapted to our clinical requirements during a testing period while maintaining acceptable acquisition times of less than 5 minutes (Table 1). During the study period, routine quality control of the MR imager was performed. However, no coil uniformity check was performed specifically for this study.

Quantitative analysis of the six evaluated sequences was performed by a third reader who was not involved in the qualitative analyses (S.R.D., with 2 years of experience in MR imaging of the musculoskeletal system). Signal intensities of articular cartilage and joint fluid, as well as image noise (standard deviation of background signal intensity), were measured with the region of interest function of workstation software (eFILM, version 1.9.4; Merge Healthcare, Milwaukee, Wis). The evaluation started with measurement of the signal intensity of the trochlear cartilage in the vertical part of the trochlear groove on the sagittal image closest to the middle of the trochlear surface where no cartilage alteration was visible with an ellipsoid region of interest. Signal intensities of the other evaluated structures were then measured with the same region of interest. The region of interest area varied from 4 to 9 mm². The noise was measured ventrally in room air and as close as possible to the knee. Contrast-to-noise ratio (CNR) and CNR efficiency were calculated for signal intensity differences between cartilage and joint fluid. CNR was calculated with the following formula: CNR = |(SI₁ – SI₂)/SD_noise|, where SI₁ is the signal intensity of the first structure evaluated, SI₂ is the signal intensity of the second structure evaluated, and SD_noise is the standard deviation of the background noise. To account for the time required for the sequences, CNR efficiency was calculated as the ratio between the CNR and the square root of sequence duration (14,15).

Reference Standard for Open Surgery and Arthroscopy
Four orthopedic surgeons (P.P.K., F.K., J.H., and M.R.S., with 12, 10, 7, and 7 years, respectively, of surgical experience) were involved in the study. The surgeons were blinded to the results of the MR examination that was performed specifically for this study. However, the surgeons made their therapeutic decisions on the basis of the clinically accepted work-up, including routinely performed imaging.

The grading scale was the same as that used for MR imaging, with the exception of grade 1 (cartilage softening without surface abnormalities instead of abnormal signal intensity without surface abnormalities). The surgeon marked any cartilage abnormality on a hand-drawn diagram of the cartilage surfaces included in the surgical report. If several abnormalities were present in any cartilage region, the worst one was used for study analysis. Two patellar surfaces were excluded from the study because they were not properly visible during surgery. Additional arthroscopy was not performed in any of the nine knees in which open surgery was performed. Open surgery (n = 9) and arthroscopy (n = 20) served as the reference standards.

Statistical Analysis
Sensitivity, specificity, and accuracy in the detection of cartilage defects were calculated for each sequence for both readers. Interobserver agreement was determined with statistics, and differences between the quantitative results were evaluated with the Wilcoxon signed rank test (SPSS software, version 11, 2001; SPSS, Chicago, Ill). To take into account the effects of multiple comparisons, the Bonferroni correction was applied, and a P value of less than .0033 was considered to indicate a statistically significant difference.

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE IMPLICATION FOR PATIENT CARE References

 
Diagnostic Performance
The cutoff for normal versus abnormal cartilage was set between grade 1 (Fig 2) and grades 2–4 (Fig 3).

View larger version (95K): [in this window] [in a new window] [Download PPT slide]   Figure 2a: Sagittal MR images obtained with (a) 3D WE true FISPthick (repetition time msec/echo time msec, 9.25/3.17; 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (repetition time msec/echo time msec/inversion time msec, 5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show normal cartilage (arrowheads). Fe = femur, Ti = tibia.

View larger version (98K): [in this window] [in a new window] [Download PPT slide]   Figure 2b: Sagittal MR images obtained with (a) 3D WE true FISPthick (repetition time msec/echo time msec, 9.25/3.17; 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (repetition time msec/echo time msec/inversion time msec, 5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show normal cartilage (arrowheads). Fe = femur, Ti = tibia.

View larger version (111K): [in this window] [in a new window] [Download PPT slide]   Figure 2c: Sagittal MR images obtained with (a) 3D WE true FISPthick (repetition time msec/echo time msec, 9.25/3.17; 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (repetition time msec/echo time msec/inversion time msec, 5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show normal cartilage (arrowheads). Fe = femur, Ti = tibia.

View larger version (91K): [in this window] [in a new window] [Download PPT slide]   Figure 2d: Sagittal MR images obtained with (a) 3D WE true FISPthick (repetition time msec/echo time msec, 9.25/3.17; 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (repetition time msec/echo time msec/inversion time msec, 5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show normal cartilage (arrowheads). Fe = femur, Ti = tibia.

View larger version (112K): [in this window] [in a new window] [Download PPT slide]   Figure 2e: Sagittal MR images obtained with (a) 3D WE true FISPthick (repetition time msec/echo time msec, 9.25/3.17; 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (repetition time msec/echo time msec/inversion time msec, 5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show normal cartilage (arrowheads). Fe = femur, Ti = tibia.

View larger version (88K): [in this window] [in a new window] [Download PPT slide]   Figure 2f: Sagittal MR images obtained with (a) 3D WE true FISPthick (repetition time msec/echo time msec, 9.25/3.17; 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (repetition time msec/echo time msec/inversion time msec, 5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show normal cartilage (arrowheads). Fe = femur, Ti = tibia.

View larger version (116K): [in this window] [in a new window] [Download PPT slide]   Figure 3a: Sagittal MR images obtained with (a) 3D WE true FISPthick (9.25/3.17, 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show grade 4 cartilage defect (arrowheads). Subchondral bone marrow alterations (arrows) may assist in the diagnosis of advanced cartilage damage and are best seen in c, d, and e. Fe = femur, Ti = tibia.

View larger version (119K): [in this window] [in a new window] [Download PPT slide]   Figure 3b: Sagittal MR images obtained with (a) 3D WE true FISPthick (9.25/3.17, 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show grade 4 cartilage defect (arrowheads). Subchondral bone marrow alterations (arrows) may assist in the diagnosis of advanced cartilage damage and are best seen in c, d, and e. Fe = femur, Ti = tibia.

View larger version (126K): [in this window] [in a new window] [Download PPT slide]   Figure 3c: Sagittal MR images obtained with (a) 3D WE true FISPthick (9.25/3.17, 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show grade 4 cartilage defect (arrowheads). Subchondral bone marrow alterations (arrows) may assist in the diagnosis of advanced cartilage damage and are best seen in c, d, and e. Fe = femur, Ti = tibia.

View larger version (122K): [in this window] [in a new window] [Download PPT slide]   Figure 3d: Sagittal MR images obtained with (a) 3D WE true FISPthick (9.25/3.17, 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show grade 4 cartilage defect (arrowheads). Subchondral bone marrow alterations (arrows) may assist in the diagnosis of advanced cartilage damage and are best seen in c, d, and e. Fe = femur, Ti = tibia.

View larger version (128K): [in this window] [in a new window] [Download PPT slide]   Figure 3e: Sagittal MR images obtained with (a) 3D WE true FISPthick (9.25/3.17, 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show grade 4 cartilage defect (arrowheads). Subchondral bone marrow alterations (arrows) may assist in the diagnosis of advanced cartilage damage and are best seen in c, d, and e. Fe = femur, Ti = tibia.

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 3f: Sagittal MR images obtained with (a) 3D WE true FISPthick (9.25/3.17, 28° flip angle), (b) 3D WE true FISPthin (9.24/3.17, 28° flip angle), (c) 2D fat-saturated intermediate-weighted spin-echo (3020/15, 150° flip angle), (d) 3D WE DESS (21.85/8.28, 20° flip angle), (e) 2D fast STIR (5460/33/160), and (f) 3D fat-saturated FLASH (39/8.89, 45° flip angle) sequences show grade 4 cartilage defect (arrowheads). Subchondral bone marrow alterations (arrows) may assist in the diagnosis of advanced cartilage damage and are best seen in c, d, and e. Fe = femur, Ti = tibia.

View larger version (19K): [in this window] [in a new window] [Download PPT slide]   Figure 4: Graph shows sensitivity. Gray and black bars show data for readers 1 and 2, respectively. Groups A and B comprise sequences with 3.0- and 1.7-mm section thickness, respectively. fs = fat-saturated.

View larger version (21K): [in this window] [in a new window] [Download PPT slide]   Figure 5: Graph shows specificity. Gray and black bars show data for readers 1 and 2, respectively. Groups A and B comprise sequences with 3.0- and 1.7-mm section thickness, respectively. fs = fat-saturated.

View larger version (19K): [in this window] [in a new window] [Download PPT slide]   Figure 6: Graph shows accuracy. Gray and black bars show data for readers 1 and 2, respectively. Groups A and B comprise sequences with 3.0- and 1.7-mm section thickness, respectively. fs = fat-saturated.

View larger version (18K): [in this window] [in a new window] [Download PPT slide]   Figure 7: Graph shows interobserver agreement ( values). Group A comprises sequences with 3.0-mm section thickness. Group B comprises sequences with 1.7-mm section thickness. fs = fat-saturated.

View larger version (14K): [in this window] [in a new window] [Download PPT slide]   Figure 8: Graph shows CNR between cartilage and fluid. Boxes represent the interquartile range, which contains 50% of values. Error bars indicate maximum and minimum values, excluding outliers. Lines across the boxes indicate the median. Group A comprises sequences with 3.0-mm section thickness. Group B comprises sequences with 1.7-mm section thickness. fs = fat-saturated.

View larger version (14K): [in this window] [in a new window] [Download PPT slide]   Figure 9: Graph shows CNR efficiency between cartilage and fluid. Boxes represent the interquartile range, which contains 50% of values. Error bars indicate maximum and minimum values, excluding outliers. Lines across the boxes indicate the median. Group A comprises sequences with 3.0-mm section thickness. Group B comprises sequences with 1.7-mm section thickness. fs = fat-saturated.

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE IMPLICATION FOR PATIENT CARE References

 
The diagnostic performance of the 3D WE true FISP_thin and 3D WE true FISP_thick sequences used in our study was comparable for both readers, although the performance with these sequences for reader 1 was consistently more specific and that for reader 2 was consistently more sensitive. Accuracy was similar for all sequences (71%–78%). No advantage in diagnosing cartilage defects was detected for sequences with 1.7-mm section thickness (3D WE DESS, 3D fat-saturated FLASH, 3D WE true FISP_thin) in comparison with sequences with a 3.0-mm section thickness (2D fat-saturated intermediate-weighted spin-echo, 2D fast STIR, 3D WE true FISP_thick). The performance with thin-section cartilage-specific sequences, such as 3D WE DESS (59%), 3D fat-saturated FLASH (58%), and 3D WE true FISP_thin (54%), was not better than that with 2D fat-saturated intermediate-weighted spin-echo (72%), 2D fast STIR (68%), and 3D WE true FISP_thick (66%) sequences. This difference is probably related to the increased signal-to-noise ratio associated with thicker sections.

The 3D WE true FISP sequences used in our study appear to represent a time-efficient alternative to other sequences commonly used to image cartilage defects. The 2D fat-saturated intermediate-weighted spin-echo and 2D fast STIR sequences may have had an advantage because they are better able to depict subchondral bone marrow abnormalities than are gradient-echo sequences. This ability may indirectly increase lesion conspicuity in advanced cartilage lesions.

Postoperative knees were not evaluated in our study. On the basis of the sensitivity to local field inhomogeneities commonly found in postoperative knees, the 3D WE true FISP sequences may not be as useful postoperatively as they are in knees in which surgery was not performed.

Unlike the results of diagnostic performance, quantitative analysis demonstrates differences for CNR and CNR efficiency values. The contrast between joint fluid and cartilage (measured as CNR) was highest for both 3D WE true FISP sequences when compared with the other sequences performed with the same section thickness. Although the increased CNR obtained with the optimized true FISP sequence did not necessarily translate into better diagnostic performance under clinical conditions, it may be helpful for advanced cartilage evaluation, such as volumetry, which requires excellent contrast between cartilage and joint fluid for segmentation.

CNR efficiency is relevant for clinical imaging because it takes imaging time into consideration. This may not be as important for research protocols in which imaging may be limited to articular cartilage and the emphasis is on highly reproducible quantitative parameters. However, CNR efficiency is relevant for clinical imaging performed under economic constraints. Several sequences are typically used to assess articular cartilage, menisci, ligaments, bone marrow, and periarticular structures. CNR efficiency renders comparison of images obtained with different sequences and inevitably variable acquisition times more meaningful. With regard to CNR efficiency between cartilage and fluid, the 3D WE true FISP_thick sequence was far superior, followed by 3D WE true FISP_thin and 2D fast STIR sequences. In a recent study, Gold et al (16) evaluated fluctuating equilibrium MR imaging, a fat-suppressed variant of steady-state free precession, for articular cartilage imaging in healthy volunteers. They found a higher CNR efficiency between cartilage and joint fluid with this sequence than with fat-suppressed fast spin-echo or 3D spoiled gradient-echo sequences. In the same study, cartilage visibility was qualitatively assessed with a four-point grading system. Cartilage visibility was better with the 3D sequences than with the fast spin-echo sequences. These results correspond to our findings. Although optimized 3D gradient-echo sequences improve cartilage imaging in comparison with 2D fast spin-echo sequences, no apparent effect on the diagnostic performance in detecting cartilage defects was shown in our study. After quantitatively assessing patellar cartilage volume at 3.0 T with 3D FLASH and 3D true FISP sequences, Weckbach et al (17) postulated that the true FISP sequence offered an advantage in monitoring disease progression in patients with osteoarthritis on the basis of its superior CNR.

We were surprised to find that the superior CNR and CNR efficiency of the 3D WE true FISP sequences had no effect on diagnostic performance in the detection of cartilage defects. This may relate to the fact that indirect signs of cartilage damage, such as signal abnormalities of subchondral bone, are not conspicuous on 3D WE true FISP images.

Our study had limitations. Complete blinding of the readers to the sequence type was not possible because their signal characteristics are quite typical. Because the most advanced abnormalities were chosen for evaluation in the presence of several lesions, the analysis may be biased toward more advanced lesions. This investigation was limited to articular cartilage and did not provide information regarding other relevant structures, including the meniscus and ligaments.

In conclusion, 3D WE true FISP is a sequence that provides good contrast between joint fluid and articular cartilage and has a diagnostic performance that is comparable with that of standard sequences.

	ADVANCES IN KNOWLEDGE

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE IMPLICATION FOR PATIENT CARE References

 

• The three-dimensional (3D) water-excitation (WE) true fast imaging with steady-state precession (FISP) sequence has a significantly (P < .0033) higher contrast-to-noise ratio (CNR) and CNR efficiency between cartilage and fluid compared with other sequences commonly used for knee imaging.
  
• The diagnostic performance of 3D WE true FISP is comparable with that of other sequences commonly used for knee imaging.
  

	IMPLICATION FOR PATIENT CARE

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE IMPLICATION FOR PATIENT CARE References

 

• True FISP may improve automatic cartilage segmentation and thus enable easier determination of cartilage volume without loss of diagnostic performance in the detection of cartilage defects.
  

	FOOTNOTES

 

Abbreviations: CNR = contrast-to-noise ratio • DESS = double echo steady state • FISP = fast imaging with steady-state precession • FLASH = fast low-angle shot • STIR = short inversion time inversion-recovery • 3D = three-dimensional • 2D = two-dimensional • WE = water excitation

Authors stated no financial relationship to disclose.

Author contributions: Guarantor of integrity of entire study, S.R.D.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, S.R.D., J.H.; clinical studies, all authors; statistical analysis, S.R.D., C.W.A.P., M.Z., J.H.; and manuscript editing, S.R.D., C.W.A.P., M.Z., J.H.

	References

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE IMPLICATION FOR PATIENT CARE References

 

1. Polster J, Recht M. Postoperative MR evaluation of chondral repair in the knee. Eur J Radiol 2005;54:206–213.[CrossRef][Medline]
2. Alparslan L, Winalski CS, Boutin RD, Minas T. Postoperative magnetic resonance imaging of articular cartilage repair. Semin Musculoskelet Radiol 2001;5:345–363.[CrossRef][Medline]
3. Eckstein F, Winzheimer M, Hohe J, Englmeier KH, Reiser M. Interindividual variability and correlation among morphological parameters of knee joint cartilage plates: analysis with three-dimensional MR imaging. Osteoarthritis Cartilage 2001;9:101–111.[CrossRef][Medline]
4. Smith HE, Mosher TJ, Dardzinski BJ, et al. Spatial variation in cartilage T2 of the knee. J Magn Reson Imaging 2001;14:50–55.[CrossRef][Medline]
5. Mosher TJ, Dardzinski BJ, Smith MB. Human articular cartilage: influence of aging and early symptomatic degeneration on the spatial variation of T2—preliminary findings at 3 T. Radiology 2000;214:259–266.[Abstract/Free Full Text]
6. Miller KL, Hargreaves BA, Gold GE, Pauly JM. Steady-state diffusion-weighted imaging of in vivo knee cartilage. Magn Reson Med 2004;51:394–398.[CrossRef][Medline]
7. Bashir A, Gray ML, Hartke J, Burstein D. Nondestructive imaging of human cartilage glycosaminoglycan concentration by MRI. Magn Reson Med 1999;41:857–865.[CrossRef][Medline]
8. Trattnig S, Mlynarik V, Breitenseher M, et al. MRI visualization of proteoglycan depletion in articular cartilage via intravenous administration of Gd-DTPA. Magn Reson Imaging 1999;17:577–583.[CrossRef][Medline]
9. Williams A, Gillis A, McKenzie C, et al. Glycosaminoglycan distribution in cartilage as determined by delayed gadolinium-enhanced MRI of cartilage (dGEMRIC): potential clinical applications. AJR Am J Roentgenol 2004;182:167–172.[Abstract/Free Full Text]
10. Schmid MR, Pfirrmann CW, Koch P, Zanetti M, Kuehn B, Hodler J. Imaging of patellar cartilage with a 2D multiple-echo data image combination sequence. AJR Am J Roentgenol 2005;184:1744–1748.[Abstract/Free Full Text]
11. Hardy PA, Recht MP, Piraino D, Thomasson D. Optimization of a dual echo in the steady state (DESS) free-precession sequence for imaging cartilage. J Magn Reson Imaging 1996;6:329–335.[Medline]
12. Knuesel PR, Pfirrmann CW, Noetzli HP, et al. MR arthrography of the hip: diagnostic performance of a dedicated water-excitation 3D double-echo steady-state sequence to detect cartilage lesions. AJR Am J Roentgenol 2004;183:1729–1735.[Abstract/Free Full Text]
13. Noyes FR, Stabler CL. A system for grading articular cartilage lesions at arthroscopy. Am J Sports Med 1989;17:505–513.[Abstract/Free Full Text]
14. Hargreaves BA, Gold GE, Beaulieu CF, Vasanawala SS, Nishimura DG, Pauly JM. Comparison of new sequences for high-resolution cartilage imaging. Magn Reson Med 2003;49:700–709.[CrossRef][Medline]
15. Kornaat PR, Doornbos J, van der Molen AJ, et al. Magnetic resonance imaging of knee cartilage using a water selective balanced steady-state free precession sequence. J Magn Reson Imaging 2004;20:850–856.[CrossRef][Medline]
16. Gold GE, Hargreaves BA, Vasanawala SS, et al. Articular cartilage of the knee: evaluation with fluctuating equilibrium MR imaging—initial experience in healthy volunteers. Radiology 2006;238:712–718.[Abstract/Free Full Text]
17. Weckbach S, Mendlik T, Horger W, Wagner S, Reiser MF, Glaser C. Quantitative assessment of patellar cartilage volume and thickness at 3.0 tesla comparing a 3D-fast low angle shot versus a 3D-true fast imaging with steady-state precession sequence for reproducibility. Invest Radiol 2006;41:189–197.[CrossRef][Medline]

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