Evaluation of Ultrafast Wave-Controlled Aliasing in Parallel Imaging 3D-FLAIR in the Visualization and Volumetric Estimation of Cerebral White Matter Lesions

BACKGROUND AND PURPOSE

Our aim was to evaluate an ultrafast 3D-FLAIR sequence using Wave-controlled aliasing in parallel imaging encoding (Wave-FLAIR) compared with standard 3D-FLAIR in the visualization and volumetric estimation of cerebral white matter lesions in a clinical setting.

MATERIALS AND METHODS

Forty-two consecutive patients underwent 3T brain MR imaging, including standard 3D-FLAIR (acceleration factor = 2, scan time = 7 minutes 50 seconds) and resolution-matched ultrafast Wave-FLAIR sequences (acceleration factor  = 6, scan time = 2 minutes 45 seconds for the 20-channel coil; acceleration factor = 9, scan time  = 1 minute 50 seconds for the 32-channel coil) as part of clinical evaluation for demyelinating disease. Automated segmentation of cerebral white matter lesions was performed using the Lesion Segmentation Tool in SPM. Student t tests, intraclass correlation coefficients, relative lesion volume difference, and Dice similarity coefficients were used to compare volumetric measurements among sequences. Two blinded neuroradiologists evaluated the visualization of white matter lesions, artifacts, and overall diagnostic quality using a predefined 5-point scale.

RESULTS

Standard and Wave-FLAIR sequences showed excellent agreement of lesion volumes with an intraclass correlation coefficient of 0.99 and mean Dice similarity coefficient of 0.97 (SD, 0.05) (range, 0.84-0.99). Wave-FLAIR was noninferior to standard FLAIR for visualization of lesions and motion. The diagnostic quality for Wave-FLAIR was slightly greater than for standard FLAIR for infratentorial lesions (P < .001), and there were fewer pulsation artifacts on Wave-FLAIR compared with standard FLAIR (P < .001).

CONCLUSIONS

Ultrafast Wave-FLAIR provides superior visualization of infratentorial lesions while preserving overall diagnostic quality and yields white matter lesion volumes comparable with those estimated using standard FLAIR. The availability of ultrafast Wave-FLAIR may facilitate the greater use of 3D-FLAIR sequences in the evaluation of patients with suspected demyelinating disease.

Evaluation of Ultrafast Wave-CAIPI MPRAGE for Visual Grading and Automated Measurement of Brain Tissue Volume

BACKGROUND AND PURPOSE

Volumetric brain MR imaging typically has long acquisition times. We sought to evaluate an ultrafast MPRAGE sequence based on Wave-CAIPI (Wave-MPRAGE) compared with standard MPRAGE for evaluation of regional brain tissue volumes.

MATERIALS AND METHODS

We performed scan-rescan experiments in 10 healthy volunteers to evaluate the intraindividual variability of the brain volumes measured using the standard and Wave-MPRAGE sequences. We then evaluated 43 consecutive patients undergoing brain MR imaging. Patients underwent 3T brain MR imaging, including a standard MPRAGE sequence (acceleration factor [R] = 2, acquisition time [TA] = 5.2 minutes) and an ultrafast Wave-MPRAGE sequence (R = 9, TA = 1.15 minutes for the 32-channel coil; R = 6, TA = 1.75 minutes for the 20-channel coil). Automated segmentation of regional brain volume was performed. Two radiologists evaluated regional brain atrophy using semiquantitative visual rating scales.

RESULTS

The mean absolute symmetrized percent change in the healthy volunteers participating in the scan-rescan experiments was not statistically different in any brain region for both the standard and Wave-MPRAGE sequences. In the patients undergoing evaluation for neurodegenerative disease, the Dice coefficient of similarity between volumetric measurements obtained from standard and Wave-MPRAGE ranged from 0.86 to 0.95. Similarly, for all regions, the absolute symmetrized percent change for brain volume and cortical thickness showed <6% difference between the 2 sequences. In the semiquantitative visual comparison, the differences between the 2 radiologists' scores were not clinically or statistically significant.

CONCLUSIONS

Brain volumes estimated using ultrafast Wave-MPRAGE show low intraindividual variability and are comparable with those estimated using standard MPRAGE in patients undergoing clinical evaluation for suspected neurodegenerative disease.

Validation of Highly Accelerated Wave-CAIPI SWI Compared with Conventional SWI and T2*-Weighted Gradient Recalled-Echo for Routine Clinical Brain MRI at 3T

BACKGROUND AND PURPOSE

SWI is valuable for characterization of intracranial hemorrhage and mineralization but has long acquisition times. We compared a highly accelerated wave-controlled aliasing in parallel imaging (CAIPI) SWI sequence with 2 commonly used alternatives, standard SWI and T2*-weighted gradient recalled-echo (T2*W GRE), for routine clinical brain imaging at 3T.

MATERIALS AND METHODS

A total of 246 consecutive adult patients were prospectively evaluated using a conventional SWI or T2*W GRE sequence and an optimized wave-CAIPI SWI sequence, which was 3-5 times faster than the standard sequence. Two blinded radiologists scored each sequence for the presence of hemorrhage, the number of microhemorrhages, and severity of motion artifacts. Wave-CAIPI SWI was then evaluated in head-to-head comparison with the conventional sequences for visualization of pathology, artifacts, and overall diagnostic quality. Forced-choice comparisons were used for all scores. Wave-CAIPI SWI was tested for superiority relative to T2*W GRE and for noninferiority relative to standard SWI using a 15% noninferiority margin.

RESULTS

Compared with T2*W GRE, wave-CAIPI SWI detected hemorrhages in more cases (P < .001) and detected more microhemorrhages (P < .001). Wave-CAIPI SWI was superior to T2*W GRE for visualization of pathology, artifacts, and overall diagnostic quality (all P < .001). Compared with standard SWI, wave-CAIPI SWI showed no difference in the presence or number of hemorrhages identified. Wave-CAIPI SWI was noninferior to standard SWI for the visualization of pathology (P < .001), artifacts (P < .01), and overall diagnostic quality (P < .01). Motion was less severe with wave-CAIPI SWI than with standard SWI (P < .01).

CONCLUSIONS

Wave-CAIPI SWI provided superior visualization of pathology and overall diagnostic quality compared with T2*W GRE and was noninferior to standard SWI with reduced scan times and reduced motion artifacts.

The role of BsmI and FokI vitamin D receptor gene polymorphisms and serum 25-hydroxyvitamin D in Brazilian patients with systemic lupus erythematosus

Vitamin D deficiency has been described in systemic lupus erythematosus (SLE). BsmI VDR (vitamin D receptor) gene polymorphism was associated with SLE in Asian patients. Studies in Brazilian populations have not been realized. A case-control study with 195 SLE patients and 201 healthy controls was conducted to investigate the influence of BsmI and FokI VDR gene polymorphisms on susceptibility to SLE. In addition, 25-hydroxyvitamin D [25(OH)D] was measured in SLE patients to evaluate possible associations with VDR polymorphic variants and clinical and laboratory expressions of disease. Genotyping was performed by RFLP-PCR. The measurement of 25(OH)D was performed by chemiluminescence. There was no statistically significant difference in genotype and allelic frequencies of BsmI and FokI polymorphisms between European-derived cases and controls. The mean serum levels of 25(OH)D were 25.51 ± 11.43 ng/ml in SLE patients. According to genotype distribution, 25(OH)D concentrations were significantly higher in patients carrying the FokI f/f genotype compared with patients carrying the F/F genotype (31.6 ± 14.1 ng/ml versus 23.0 ± 9.2 ng/ml, p = 0.004), reinforcing its role in the functional activity of VDR. This feature may be considered in future clinical and experimental studies involving vitamin D measurements. Therefore, genetic-specific definitions of ideal levels of vitamin D in SLE need to be established in future studies.