Application of three-dimensional SPACE magnetic resonance imaging in accurate measurement of implant volume in breast surgery / 中华整形外科杂志

Objective@#The study is to assess the accuracy and reliability of three-dimensional simulated magnetic resonance imaging with silicone-excitation SPACE (sampling perfection with application optimized contrast using different flip angle evolutions) sequence for estimating implant volume.@*Methods@#(1) MRI examinations of 10 silicone implants (Wuhan Tongji Hospital from October 2018 to December 2018) were performed with T2, H2O-excitation SPACE sequence (T2-spc-H2O) and silicone-excitation SPACE sequence (T2-spc-Silicone) to find the most accurate method to estimate implant volume by ITK-SNAP. The effect of implant deformation and slice thickness of T2-spc-Silicone on volume measurement were investigated. (2) 13 normal patients and 6 patients with implant complications (Wuhan Tongji Hospital from March 2017 to May 2019) were enrolled for testing the accuracy and reliability of T2-spc-Silicone for volume measurement in vivo. The data were analyzed using Prism 8.0 software. The paired student t-test was used to compare the difference of two groups. One-way ANOVA was used to compare the difference of multiple groups. P<0.05 was considered statistically significant.@*Results@#The absolute volume differences of T2, T2-spc-H2O, T2-spc-Silicone were (42.19±2.31) ml, (23.27±1.55) ml and (6.28±1.22) ml. The absolute volume differences of T2-spc-Silicone group was significantly less than T2-spc-H2O and T2 group in vitro(F=195.3, P<0.001). No significant difference(F=1.36, P=0.22)was shown between the normality group and the deformation group for estimating the volume of implants with the slice thickness of SPACE increased from 0.5 mm×0.5 mm×0.5 mm to 5.0 mm×5.0 mm×5.0 mm. Besides, the slices thickness of SPACE from 0.5 mm×0.5 mm×0.5 mm to 5.0 mm×5.0 mm×5.0 mm did not significantly affect the accuracy of volume measurement of the implants in deformation state(F=1.22, P=0.29). The measurement error of SPACE was (8.82±0.99) ml in normal patients. Moreover, there was no significant difference between measured volume[(226.4±12.76)ml] and actual volume of implants[(225.9±11.94) ml](t=0.31, P=0.76)in patients with implant complications. The result showed excellent intraobserver reliability (ICC=0.997) and internal consistency ranged from 0.986 to 0.997 (P<0.001).@*Conclusions@#The method to measure implant volume by silicone-excitation SPACE sequence had desirable accuracy and reliability. The deformation of the implant and the slice thickness of the SPACE sequence did not exhibit a significant effect on the accuracy of volume measurement.

Self-Gated Late Gadolinium Enhancement at 7T to Image Rats with Reperfused Acute Myocardial Infarction

OBJECTIVE: A failed electrocardiography (ECG)-trigger often leads to a long acquisition time (TA) and deterioration in image quality. The purpose of this study was to evaluate and optimize the technique of self-gated (SG) cardiovascular magnetic resonance (CMR) for cardiac late gadolinium enhancement (LGE) imaging of rats with myocardial infarction/reperfusion. MATERIALS AND METHODS: Cardiovascular magnetic resonance images of 10 rats were obtained using SG-LGE or ECG with respiration double-gating (ECG-RESP-gating) method at 7T to compare differences in image interference and TA between the two methods. A variety of flip angles (FA: 10°–80°) and the number of repetitions (NR: 40, 80, 150, and 300) were investigated to determine optimal scan parameters of SG-LGE technique based on image quality score and contrast-to-noise ratio (CNR). RESULTS: Self-gated late gadolinium enhancement allowed successful scan in 10 (100%) rats. However, only 4 (40%) rats were successfully scanned with the ECG-RESP-gating method. TAs with SG-LGE varied depending on NR used (TA: 41, 82, 154, and 307 seconds, corresponding to NR of 40, 80, 150, and 300, respectively). For the ECG-RESP-gating method, the average TA was 220 seconds. For SG-LGE images, CNR (42.5 ± 5.5, 43.5 ± 7.5, 54 ± 9, 59.5 ± 8.5, 56 ± 13, 54 ± 8, and 41 ± 9) and image quality score (1.85 ± 0.75, 2.20 ± 0.83, 2.85 ± 0.37, 3.85 ± 0.52, 2.8 ± 0.51, 2.45 ± 0.76, and 1.95 ± 0.60) were achieved with different FAs (10°, 15°, 20°, 25°, 30°, 35°, and 40°, respectively). Optimal FAs of 20°–30° and NR of 80 were recommended. CONCLUSION: Self-gated technique can improve image quality of LGE without irregular ECG or respiration gating. Therefore, SG-LGE can be used an alternative method of ECG-RESP-gating.

Diagnosis of Nerve Root Compromise of the Lumbar Spine: Evaluation of the Performance of Three-dimensional Isotropic T2-weighted Turbo Spin-Echo SPACE Sequence at 3T

OBJECTIVE: To explore the performance of three-dimensional (3D) isotropic T2-weighted turbo spin-echo (TSE) sampling perfection with application optimized contrasts using different flip angle evolution (SPACE) sequence on a 3T system, for the evaluation of nerve root compromise by disc herniation or stenosis from central to extraforaminal location of the lumbar spine, when used alone or in combination with conventional two-dimensional (2D) TSE sequence. MATERIALS AND METHODS: Thirty-seven patients who had undergone 3T spine MRI including 2D and 3D sequences, and had subsequent spine surgery for nerve root compromise at a total of 39 nerve levels, were analyzed. A total of 78 nerve roots (48 symptomatic and 30 asymptomatic sites) were graded (0 to 3) using different MRI sets of 2D, 3D (axial plus sagittal), 3D (all planes), and combination of 2D and 3D sequences, with respect to the nerve root compromise caused by posterior disc herniations, lateral recess stenoses, neural foraminal stenoses, or extraforaminal disc herniations; grading was done independently by two readers. Diagnostic performance was compared between different imaging sets using the receiver operating characteristics (ROC) curve analysis. RESULTS: There were no statistically significant differences (p = 0.203 to > 0.999) in the ROC curve area between the imaging sets for both readers 1 and 2, except for combined 2D and 3D (0.843) vs. 2D (0.802) for reader 1 (p = 0.035), and combined 2D and 3D (0.820) vs. 3D including all planes (0.765) for reader 2 (p = 0.049). CONCLUSION: The performance of 3D isotropic T2-weighted TSE sequence of the lumbar spine, whether axial plus sagittal images, or all planes of images, was not significantly different from that of 2D TSE sequences, for the evaluation of nerve root compromise of the lumbar spine. Combining 2D and 3D might possibly improve the diagnostic accuracy compared with either one.

Comparison of the diagnostic value of double echo steady state sequences with 30°and 90° flig angle for knee articular cartilage damage / 实用放射学杂志

Objective To compare the diagnostic accuracy of 3D-DESS sequences with 30°and 90°flip angles for the knee articular cartilage injury (≥Grade 2).Methods Images of 13 patients (2 men,1 1 women,age range 18-68 years)of the knee articular carti-lage injury were obtained with 3D-DESS flip angles of 30°and 90°at 1.5T MR.Two radiologists classified the presence or absence of cartilage damage of ≥Grade 2 as positive (P)or