The Role of Double Inversion Recovery Imaging in Acute Ischemic Stroke

PURPOSE: The purpose of this study was to investigate if double inversion recovery (DIR) imaging can have a role in the evaluation of brain ischemia, compared with diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) imaging. MATERIALS AND METHODS: Sixty-seven patients within 48 hours of onset, underwent MRI scans with FLAIR, DWI with b-value of 0 (B0) and 1000 s/mm², and DIR sequences. Patients were categorized into four groups: within three hours, three to six hours, six to 24 hours, and 24 to 48 hours after onset. Lesion-to-normal ratio (LNR) value was calculated and compared among all sequences within each group, by the Friedman test and conducted among all groups, for each sequence by the Kruskal-Wallis test. In qualitative assessment, signal intensity changes of DIR, B0, and FLAIR based on similarity with DWI and image quality of each sequence, were graded on a 3-point scale, respectively. Scores for detectability of lesions were compared by the McNemar's test. RESULTS: LNR values from DWI were higher than DIR, but not statistically significant in all groups (P > 0.05). LNR values of DIR were significantly higher than FLAIR within 24 hours of onset (P < 0.05). LNR values were significantly different between, before, and after six hours onset time for DIR (P = 0.016), B0 (P = 0.008), and FLAIR (P = 0.018) but not for DWI (P = 0.051). Qualitative analysis demonstrated that detectability of DIR was higher, compared to that of FLAIR within 4.5 hours and six hours of onset (P < 0.05). Also, the DWI quality score was lower than that of DIR, particularly relative to infratentorial lesions. CONCLUSION: DIR provides higher detectability of hyperacute brain ischemia than B0 and FLAIR, and does not suffer from susceptibility artifact, unlike DWI. So, DIR can be used to replace evaluation of the FLAIR-DWI mismatch.

Investigation of Correlations of Double Inversion Recovery and MR Spectroscopy on Breast MR Imaging

PURPOSE: To evaluate the correlation of lesion-to-normal ratio (LNR) of signal intensity from double inversion recovery MR imaging and total choline-containing compound (tCho) resonance from single voxel MR spectroscopy in breast cancers. MATERIALS AND METHODS: Between August 2008 and December 2009, 28 patients who were diagnosed as breast cancer and had undergone both double inversion recovery (DIR) MR imaging and MR spectroscopy (MRS) were included in this study. The signal intensities of the lesion (L) and ipsilateral normal breast tissue (N) were measured in region of interest of each breast cancer in DIR and contrast enhance MR image (CE-T1WI) to calculate the LNR value for each technique. MRS was performed using single-voxel MR spectroscopy. The height, width and area of tCho resonance were compared with each LNR of DIR and CE-T1WI. We used Pearson's correlation coefficient (r) for correlation analysis and the significance level was p=0.05. RESULTS: There was no statistically significant correlation between LNR of CE-T1WI and height (r=-0.322, p=0.094), width (r=-0.233, p=0.232) and area (r=-0.309, p=0.109) of MRS tCho. There was no statistically significant correlation between LNR of DIR and height (r=0.067, p=0.735), width (r=-0.287, p=0.139) and area (r=0.012, p=0.953) of MRS tCho, either. The Pearson's correlation coefficient was 0.186 between LNRs of CE-T1WI and DIR (p=0.344). CONCLUSION: There was no statistically significant correlation between LNR of DIR and relative amount of tCho resonance of MRS.

Using double inversion recovery sequence for the diagnosis of hippocampal sclerosis at 3.0 T MR / 中华放射学杂志

Objective To investigate the imaging feature of hippocampal sclerosis (HS), and evaluate the diagnostic value of double inversion recovery (DIR) sequence at 3.0 T MR for its diagnosis. Methods Twelve patients with unilateral HS proven by pathology and 12 healthy volunteers were enrolled. All patients received DIR, fluid attenuated inversion recovery (FLAIR) and T2 TSE sequences scans on oblique coronal plane vertical to the hippocampal axis on a 3.0 T MR scanner. Regions of interest (ROI) were set respectively in ipsilateral and contralateral hippocampi hippocampi in patients with HS, and the bilateral hippocampi in healthy volunteneers were placed respectively. Signal to noise ratio (SNR), contrast to noise ratio (CNR), ratio of signal intensity (RSI) and asymmetry index (AI) of each ROI in all hippocampi were calculated and compared among the three sequences. Statistical analysis was performed with one-way ANOVA. Results On DIR images, ipsilateral hippocampal lesions demonstrated extremely high signal intensity. Relative signal intensity of ipsilateral hippocampal lesions, contralateral hippocampi and the hippocampi in control groups healthy volunteneers were 1.50±0.05, 1.26±0.03, 1.18±0.05 (F=172.609,P=0.000), respectively. SNR of ipsilateral hippocampal lesions on DIR, FLAIR and T2 TSE sequences were 84.13±16.62, 50.90±12.38, 63.25±15.46 (F=15.185,P=0.000), respectively. CNR of hippocampus were 13.72±3.73, 6.67±3.02, 7.33±3.65 (F=14.985,P=0.000), respectively.In HS patients, RSI and AI of the ipsilateral hippocampal lesions and contralateral hippocampi among the three sequences did not show statistically significant difference(P=0.078). Conclusions HS manifests extremely high signal intensity on DIR images. On DIR images, the SNR and CNR of HS were higher than those on conventional MR sequences which provide valuable information for the diagnosis of HS.