Objective. The purpose of this study was to determine the potential of fluid attenuated inversion recovery (FLAIR) sequence images in the identification of joint effusion (JE) in comparison with T2-weighted images.Study design. A total of 31 joints (28 patients) with JE were investigated by magnetic resonance imaging. Regions of interest were placed over JE, cerebrospinal fluid (CSF) and gray matter (GM) on T2-weighted and FLAIR images and their signal intensities compared. The signal intensity ratios (SIRs) of JE and CSF were calculated used GM as the reference point. The Pearson product-moment correlation coefficient was used for the statistical analysis.Result. The SIR of JE showed a strong correlation between T2-weighted and FLAIR images. However, no correlation was observed for CSF. The average suppression ratio for JE was lower than that for CSF. According to the inclusion and exclusion criteria (Table I), 201 joints were excluded from this study. A total of 31 joints of 28 patients were studied. A total of 31 joints of 28 patients were studied. There were 4 males and 24 females. The mean age of the patients was 39.9 years with an age range of 13 to 76 years.
ConclusionAll images were obtained with the 1. The signal intensity ratio (SIR)s of JE and CSF were calculated as follows: SIR = the signal intensity of JE or CSF/the signal intensity of GM. In the FLAIR sequence images, the patients were divided into Group A (TE, 122 ms) and Group B (TE, 168 ms) for the statistical analysis. The Pearson product-moment correlation coefficient was used to assess the correlation between the SIRs on the T2-weighted and FLAIR images of both JE and CSF. A probability of less than 0.05 was considered statistically significant. The suppression ratios of the signal intensities in FLAIR imaging were also compared according to the following equation: (SIR of T2-weighted imagesSIR of FLAIR images)/SIR of T2-weighted images × 100 (Figure 3).
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ResultsThe SIRs obtained for JE and CSF on T2-weighted and FLAIR images are shown in Table III. The average SIR of JE was higher than that of CSF on both T2-weighted and FLAIR images in both Groups A and B.A strong correlation between T2-weighted images and FLAIR images was obtained for JE in both groups. The correlation coefficient was 0.81 in Group A and 0.94 in Group B (Figures 4 and 5). On the other hand, no correlation was found between the two sets of images for CSF (0.09 in Group A、-0.33 in Group B).The average suppression ratio for the signal intensity of JE by FLAIR imaging was 36.9% in Group A and 16.3% in Group B. The ratio for CSF was 75.6% in Group A and 71.7% in Group B (Table IV). The signal intensity of CSF was suppressed more markedly than that of JE.7
DiscussionJoint effusion is considered to be a pathological collection of joint fluid that can only be observed on T2-weighted images. Hitherto, the only way to determine the presence of JE has been by amount of fluid present in the joint. We hypothesized that the FLAIR technique would provide additional inform...