Free-Breathing Three-Dimensional Isotropic-Resolution MR sequence for simultaneous vessel wall imaging of bilateral renal arteries and abdominal aorta: Feasibility and reproducibility

Evaluation of Intra-Aneurysmal Residual Blood Flow with the iMSDE T1-Black Blood Imaging after Flow Diverter Treatment

Objective

We aimed to evaluate the efficacy of the "improved motion-sensitized driven-equilibrium (iMSDE)"-prepared T1-weighted black blood (T1-BB) MRI for monitoring treatment effect with a flow diverter (FD) for cerebral aneurysms.

Methods

Following the exclusion of concomitant coiling and retreatment cases from 60 consecutive cases of cerebral aneurysms treated with FDs at our institution, 32 with imaging data were included in the analysis. Detectability of residual blood flow within the aneurysms was validated as follows: 1) comparison of MRI sequences (iMSDE-prepared T1-BB images, T1-weighted images [ T1WI], and time-of-flight [ TOF]-MRA) in cases of incompletely occluded aneurysms and 2) comparison of angiography and MRI sequences in the same period.

Results

1) The probability of diagnosing intra-aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB (iMSDE-prepared T1-BB vs. T1WI, p <0.001; iMSDE-prepared T1-BB vs. TOF-MRA, p <0.001). 2) The diagnostic accuracy of residual aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB than that with T1WI (p = 0.032). Furthermore, in cases of incomplete occlusion, the probability of detecting intra-aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB (iMSDE-prepared T1-BB vs. T1WI, p <0.001; iMSDE-prepared T1-BB vs. TOF-MRA, p = 0.023).

Conclusion

Our results demonstrated that iMSDE-prepared T1-BB could help distinguish between blood flow and thrombus within the aneurysms after FD treatment, especially in the early stages of FD treatment.

Reliability and Value of 3D Sequential QUantitative T1 -T2 -T2 * MAppings (SQUMA) MR Multi-Parametric Imaging in Characterizing Carotid Artery Atherosclerosis

BACKGROUND

T₁ , T₂ , and T₂ * mappings are seldom performed in a single examination, and their values in evaluating symptomatic atherosclerosis are lacking.

PURPOSE

To perform three-dimensional (3D) quantitative T₁ , T₂ , and T₂ * mappings (SQUMA) multi-parametric imaging for carotid vessel wall and evaluate its reliability and value in assessing carotid atherosclerosis.

STUDY TYPE

Prospective.

SUBJECTS

Eight healthy subjects and 20 patients with symptomatic carotid atherosclerosis.

FIELD STRENGTH/SEQUENCE

3 T, SQUMA imaging T₁ -, T₂ -, and T₂ *-mapping, multi-contrast vessel wall imaging including T₁ - and T₂ -weighted, time-of-flight, and SNAP sequences.

ASSESSMENT

SQUMA was acquired in all subjects and multi-contrast images were acquired in healthy subjects. T₁ , T₂ , and T₂ * values and lumen area (LA), wall area (WA), mean wall thickness (MeanWT), and normalized wall index (NWI) of carotid arteries were measured. SQUMA and multi-contrast measurements were compared in healthy subjects and differences in SQUMA measurements between healthy subjects and patients were assessed. The discriminative value of SQUMA measurements for symptomatic vessel was determined.

STATISTICAL TESTS

Paired t or Wilcoxon signed-rank test, independent t or Mann-Whitney U test, area under the receiver operating characteristic curve (AUC), intraclass correlation coefficients, and Bland-Altman plots. Statistically significant level, P < 0.05.

RESULTS

There were no significant differences in LA (P = 0.340), WA (P = 0.317), MeanWT (P = 0.088), and NWI (P = 0.091) of carotid arteries between SQUMA and multi-contrast vessel wall images. The values of T₂ (50.9 ± 2.9 msec vs. 44.5 ± 4.2 msec), T₂ * (28.2 ± 4.3 msec vs. 24.7 ± 2.6 msec), WA (23.7 ± 4.6 mm² vs. 36.2 ± 7.7 mm² ), MeanWT (0.99 ± 0.05 mm vs. 1.50 ± 0.28 mm), and NWI (40.7 ± 3.0% vs. 53.8 ± 5.4%) of carotid arteries in healthy subjects were significantly different from those in atherosclerotic patients. The combination of quantitative T₁ , T₂ , and T₂ * values and MeanWT showed greatest AUC (0.81; 95% CI: 0.65-0.92) in discriminating symptomatic vessels.

DATA CONCLUSION

Carotid MR 3D quantitative multi-parametric imaging of SQUMA enables acquisition of T₁ , T₂ , and T₂ * maps, reliably measuring carotid morphology and discriminating carotid symptomatic atherosclerosis.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.