3T 자기공명영상 장비에서 신생아 뇌의 T1 강조 영상: 스핀에코, 고속 역전회복, 자기화 삼차원 경사에코기법의 비교 T1-weighted MR Imaging of the Neonatal Brain at 3.0 Tesla: Comparison of Spin Echo, Fast Inversion Recovery, and Magnetization-prepared Three Dimensional Gradient Echo Techniques원문보기
목적: 3T 장비의 신생아 뇌자기공명영상에서 T1 강조 고속 역전회복기법 (fast inversion recovery, FIR)과 자기화 삼차원 경사에코기법, (magnetization-prepared three dimensional gradient echo sequence, 3D GRE)을 스핀에코기법 (SE)과 비교하여 유용성을 알아보는 데 있다. 대상 및 방법: 20명의 신생아에서 T1 강조 SE, FIR, 그리고 3D GRE의 신호소음비 (SNR)와 대조소음비 (CNR)를 측정하고 시각적으로 회백질-백질 구별, 수초화 인식, 인공음영 발생을 점수화하여 비교하였다. 각 영상기법의 CNR 비교에는 Wilcoxon signed ranked test를 사용하였다. 결과: 세가지 영상기법 중 3D GRE가 가장 우수한 SNR을 보였고 CNR은 FIR과 3D GRE 모두 SE보다 우수하였으며 FIR보다 3D GRE가 더 우수하였다. 회백질-백질의 구분과 수초화 유무 역시 스핀에코보다 FIR과 3D GRE에서 더 잘 보였다. 그러나 3D GRE는 움직임에 의한 인공음영이 많았고 FIR에서 혈류에 의한 혈관의 고신호강도가 자주 발견되었다. 결론: 3T 장비에서 신생아 뇌영상을 얻을 때 FIR과 3D GRE 기법은 SE보다 좋은 T1 강조영상을 제공할 것으로 기대된다.
목적: 3T 장비의 신생아 뇌자기공명영상에서 T1 강조 고속 역전회복기법 (fast inversion recovery, FIR)과 자기화 삼차원 경사에코기법, (magnetization-prepared three dimensional gradient echo sequence, 3D GRE)을 스핀에코기법 (SE)과 비교하여 유용성을 알아보는 데 있다. 대상 및 방법: 20명의 신생아에서 T1 강조 SE, FIR, 그리고 3D GRE의 신호소음비 (SNR)와 대조소음비 (CNR)를 측정하고 시각적으로 회백질-백질 구별, 수초화 인식, 인공음영 발생을 점수화하여 비교하였다. 각 영상기법의 CNR 비교에는 Wilcoxon signed ranked test를 사용하였다. 결과: 세가지 영상기법 중 3D GRE가 가장 우수한 SNR을 보였고 CNR은 FIR과 3D GRE 모두 SE보다 우수하였으며 FIR보다 3D GRE가 더 우수하였다. 회백질-백질의 구분과 수초화 유무 역시 스핀에코보다 FIR과 3D GRE에서 더 잘 보였다. 그러나 3D GRE는 움직임에 의한 인공음영이 많았고 FIR에서 혈류에 의한 혈관의 고신호강도가 자주 발견되었다. 결론: 3T 장비에서 신생아 뇌영상을 얻을 때 FIR과 3D GRE 기법은 SE보다 좋은 T1 강조영상을 제공할 것으로 기대된다.
Purpose: The purpose of this study was to evaluate the usefulness of fast inversion recovery (FIR) and magnetization-prepared three dimensional gradient echo sequence (3D GRE) T1-weighted sequences for neonatal brain imaging compared with spin echo (SE) sequence in a 3T MR unit. Materials and Method...
Purpose: The purpose of this study was to evaluate the usefulness of fast inversion recovery (FIR) and magnetization-prepared three dimensional gradient echo sequence (3D GRE) T1-weighted sequences for neonatal brain imaging compared with spin echo (SE) sequence in a 3T MR unit. Materials and Methods: T1-weighted axial SE, FIR and 3D GRE sequences were evaluated from 3T brain MR imaging in 20 neonates. The signal-to-noise ratio (SNR) of different tissues was measured and contrast-to-noise ratios (CNR) were determined and compared in each of the sequences. Visual analysis was carried out by grading gray-white matter differentiation, myelination, and artifacts. The Wilcoxon signed ranked test was used for evaluation of the statistical significance of CNR differences between the sequences. Results: Among the three sequences, the 3D GRE had the best SNRs. CNRs obtained with FIR and 3D GRE were statistically superior to those obtained with SE; these CNRs were better on the 3D GRE compared to the FIR. Gray to white matter differentiation and myelination were better delineated on the FIR and 3D GRE than the SE. However, motion artifacts were more commonly observed on the 3D GRE and flow-related artifacts of vessels were frequently seen on the FIR. Conclusion: FIR and 3D GRE are valuable alternative T1-weighted sequences to conventional SE imaging of the neonatal brain at 3T providing superior image quality.
Purpose: The purpose of this study was to evaluate the usefulness of fast inversion recovery (FIR) and magnetization-prepared three dimensional gradient echo sequence (3D GRE) T1-weighted sequences for neonatal brain imaging compared with spin echo (SE) sequence in a 3T MR unit. Materials and Methods: T1-weighted axial SE, FIR and 3D GRE sequences were evaluated from 3T brain MR imaging in 20 neonates. The signal-to-noise ratio (SNR) of different tissues was measured and contrast-to-noise ratios (CNR) were determined and compared in each of the sequences. Visual analysis was carried out by grading gray-white matter differentiation, myelination, and artifacts. The Wilcoxon signed ranked test was used for evaluation of the statistical significance of CNR differences between the sequences. Results: Among the three sequences, the 3D GRE had the best SNRs. CNRs obtained with FIR and 3D GRE were statistically superior to those obtained with SE; these CNRs were better on the 3D GRE compared to the FIR. Gray to white matter differentiation and myelination were better delineated on the FIR and 3D GRE than the SE. However, motion artifacts were more commonly observed on the 3D GRE and flow-related artifacts of vessels were frequently seen on the FIR. Conclusion: FIR and 3D GRE are valuable alternative T1-weighted sequences to conventional SE imaging of the neonatal brain at 3T providing superior image quality.
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문제 정의
The purpose of this study was to evaluate the usefulness of the FIR and 3D GRE Tl-weighted sequences for neonatal brain imaging compared with the conventional SE sequence in a 3T MR unit.
제안 방법
For the quantitative assessment, images were realigned using View Forum software; the signal-to- noise ratio (SNR) and contrast-to-noise ratios (CNR) were determined and compared. Signal intensities of the white matter (WM), gray matter (GM), myelinated parenchyma (MP) and unmyelinated parenchyma (UP) were measured for each sequence.
MR examinations were performed on a 3.0T whole body MR scanner (Gyroscan Intera Achieva; Philips Medical Systems, Bestf Netherlands) using a head coil for transmitting and receiving signals. Axial FIR and 3D GRE Tl-weighted sequences were included in the routine brain MR imaging which included SE Tl- weighted axial, FLAIR axial, and fast SE T2-weighted axial/coronal imaging.
Axial FIR and 3D GRE Tl-weighted sequences were included in the routine brain MR imaging which included SE Tl- weighted axial, FLAIR axial, and fast SE T2-weighted axial/coronal imaging. Sagittal acquisition of the 3D GRE images was performed to reduce scan time and reconstructed axial and coronal images were displayed in the PACS system. The estimated total scan time was less than 25 minutes.
We protected the body temperature by using blankets and warm saline bags. They were monitored with pulse oximetry, EKG and video camera throughout the examination. The attending doctor stayed in the MR station as is standard for MR examinations of neonates and young infants at our institution.
Visual assessment was performed by three radiologists independently according to GM-WM differentiation, conspicuity of myelination and the presence of artifact. The artifacts included motion artifact and flow-related artifact of the vessels.
대상 데이터
A total of 20 neonates and young infants were included in this study. MR imaging was requested by clinicians for a suspected brain lesion or follow-up after serial cranial sonography according to the neonatal intensive care unit follow-up protocol.
of artifact. The artifacts included motion artifact and flow-related artifact of the vessels. We compared combinations of three sequences (SE vs.
MR imaging was requested by clinicians for a suspected brain lesion or follow-up after serial cranial sonography according to the neonatal intensive care unit follow-up protocol. They were thirteen boys and seven girls. The corrected gestational age when the MR imaging was performed ranged from 33 to 44 weeks with a median of 38 weeks.
데이터처리
CNRs of GM versus WM and UP versus MP were defined as the ratio of the signal difference between two tissues and the background noise. The Wilcoxon signed rank test was used to compare the differences in CNRs between each of the sequences.
성능/효과
In conclusion, both FIR and 3D GRE sequences are valuable alternatives to T1 sequences; they provide improved image quality compared to the conventional SE technique for neonatal brain imaging.
Limitations of our study included the absence of evaluation of lesion detection and enhancement after contrast administration; this was because parenchymal lesions were identified in only in a small number of the babies during the study period, and enhancement was not included in our routine MR imaging protocol unless there was suspicion of infection or neoplasm. Gray-to- white matter contrast in T1 spin-echo images at 3T field strength is known to be improved by using a lowered flip angle (50 degrees) (17).
Our results demonstrated that both FIR and 3D GRE were superior compared to SE in terms of the CNRs between different tissues. Although the quantitative analysis revealed that the CNRs of the 3D GRE were superior to those of the FIR, visual analysis revealed that images obtained with FIR were comparable to those obtained with 3D GRE.
The values for the CNRs were about twice higher for FIR than for SE, and three times higher for 3D GRE than for SE imaging. The GM- WM and MP-UP CNRs obtained with FIR and 3D GRE were statistically superior to those obtained by the SE technique; these CNRs on the 3D GRE were statistically superior to the FIR except for perirolandic white matter (table 4).
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