Carotid wall imaging with 3D_T2_FFE: sequence parameter optimization and comparison with 3D_T2_SPACE.

Similar to sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE), T2-weighted fast field echo (FFE) also has a black blood effect and a high imaging efficiency. The purpose of this study was to optimize 3D_T2_FFE and compare it with 3D_T2_SPACE for carotid imaging. The scanning parameter of 3D_T2_FFE was optimized for the imaging of the carotid wall. Twenty healthy volunteers and 10 patients with carotid plaque underwent cervical 3D_T2_FFE and 3D_T2_SPACE examinations. The signal-to-noise ratios of the carotid wall (SNRwall) and lumen (SNRlumen), and the contrast-to-noise ratios between the wall and lumen (CNRwall_lumen) were compared. The incidence of the residual flow signal at the carotid bifurcation and the grades of flow voids in the cerebellopontine angle region in the two sequences were also compared. The reproducibility of the two sequences was tested. No significant difference was observed between the two sequences in terms of the SNRwall of healthy individuals and patients (P = 0.132 and 0.102, respectively). The SNRlumen in the 3D_T2_FFE images was lower than that in the 3D_T2_SPACE images. No significant difference was observed between the two sequences in terms of the CNRwall-lumen. The incidence of the residual flow signal at the carotid bifurcation in 3D_T2_FFE was significantly lower than that in 3D_T2_SPACE. The grades of flow suppression in the cerebellopontine angle region in 3D_T2_SPACE was lower than that in 3D_T2_FFE. Both sequences showed excellent inter-and intra-observer reproducibility. Compared to 3D_T2_SPACE, 3D_T2_FFE showed stronger flow suppression while maintaining good imaging quality, which can be used as an alternative tool for carotid imaging.

T2-weighted balanced steady-state free procession MRI evaluated for diagnosing placental adhesion disorder in late pregnancy.

OBJECTIVE: This study evaluated the imaging characteristics and accuracy of T2-weighted (T2W) balanced steady-state free procession (b-SSFP) magnetic resonance imaging, relative to b-SSFP or single-shot fast spin echo (SSFSE), for the diagnosis of placental adhesion disorder (PAD). METHODS: Fifty-one pregnant patients suspected of PAD were examined with T2W b-SSFP, b-SSFP and SSFSE. The image types were independently analysed for signs of PAD: abnormal placental bulge (APB), dark intraplacental bands (DIB), placental heterogeneity (PH) and placental protrusion into adjacent structures (PPAS). The sequences were compared for muscle-to-placenta signal ratio, signs of PAD and area under the receiver operating characteristic curve (AUC) for diagnostic accuracy of PAD. RESULTS: PAD was confirmed in 34 women. The muscle-to-placenta signal ratio was highest in the T2W b-SSFP. The diagnostic rates of APB in T2W b-SSFP were comparable to that of b-SSFP, but were significantly higher than that of SSFSE. The rates of PH in SSFE were comparable to that of b-SSFP, but both were significantly lower than that of T2W b-SSFP. The rates of DIB were significantly higher in T2W b-SSFP images compared with SSFSE. Rates of PPAS were comparable among three sequences. The AUCs of the T2W b-SSFP, b-SSFP and SSFSE were 0.966, 0.890 and 0.823, respectively. CONCLUSION: T2W b-SSFP has high diagnostic accuracy for PAD relative to SSFSE or b-SSFP, which may be due to its high SNR, T2-weighting and lack of blur. KEY POINTS: • Signal myometrium-to-placenta ratio was highest in the T2W b-SSFP images. • Diagnostic rate of APB in T2W b-SSFP was highest. • Diagnostic rate of DIB was higher in T2W b-SSFP than in SSFSE. • Diagnostic rate of PH in T2W b-SSFP was highest. • Maximum AUC for diagnostic accuracy of PAD was in T2W b-SSFP.

A Multimodal Magnetic Resonance Imaging Study of Recovery of Consciousness in Severe Traumatic Brain Injury: Preliminary Results.

Accurate and reliable assessment of the conscious state of patients with severe traumatic brain injury (TBI) is vital for their future management. The purpose of the present study is to find an effective and accurate magnetic resonance imaging (MRI) method for predicting recovery of consciousness in patients with severe TBI. Multimodal MR techniques, including structural MRI, MR spectroscopy (MRS), diffusion tensor imaging (DTI), were used to evaluate brain damage in 58 patients with severe TBI. Statistical analysis compared imaging results and recovery over a relatively long period to find the most potent prognostic indicators and predictive method. A total 33 patients gained recovery of consciousness (RC), and 25 did not (NRC). Compared with the RC group, those in the NRC group had a significantly lower N-acetylaspartate to creatine (NAA/Cr) ratio of pons (1.43 ± 0.54 vs. 1.70 ± 0.42), more fiber lines (1046.3 ± 100.8 vs. 975.6 ± 128.1), less peripheral grey matter (pgrey) (579.23 ± 78.85 vs. 638.23 ± 61.16), lower fractional anisotropy (FA) of fibers (0.42 ± 0.04 vs. 0.45 ± 0.03), older age (43.08 ± 14.61 vs. 30.57 ± 12.89), and higher apparent diffusion coefficient (ADC) of fibers (0.99 ± 0.14 vs. 0.89 ± 0.06); all p < 0.05. Age, pgrey, ADC of fibers, NAA/Cr of pons were selected by logistic regression analysis to predict RC, with p values of 0.033 and 0.031, 0.035, 0.030, respectively. Age, pgrey, ADC of fibers, NAA/Cr of pons are effective indicators in the predictive model of RC.