1.Feasibility of Novel Three-Dimensional Magnetic Resonance Fingerprinting of the Prostate Gland:Phantom and Clinical Studies
Dongyeob HAN ; Moon Hyung CHOI ; Young Joon LEE ; Dong-Hyun KIM
Korean Journal of Radiology 2021;22(8):1332-1340
Objective:
To evaluate the feasibility of a new three-dimensional (3D) MR fingerprinting (MRF) technique for the prostate gland by conducting phantom and clinical studies.
Materials and Methods:
The new 3D MRF technique used in this study enables quick data acquisition and has a high resolution. For the phantom study, the MRF T1 and T2 values in an in-house phantom were compared with those of goldstandard mapping methods using linear regression analysis. For the clinical study, we evaluated 90 patients who underwent prostate imaging with MRF for suspected prostate cancer between September 2019 and February 2020. The mean T1 and T2 values were compared in the peripheral zone, transition zone, and focal lesions using paired t tests. The differences in the T1 and T2 values according to cancer aggressiveness were evaluated using one-way analysis of variance.
Results:
In the phantom study, the MRF T1 and T2 values showed a perfect correlation with the gold-standard T1 and T2 values (R > 0.99). In the clinical study, the T1 and T2 values in the peripheral zone were significantly higher than those in the transitional zone (p < 0.001, both). The T1 and T2 values in prostate cancer were significantly lower than those in the peripheral and transitional zones. The higher the grade of cancer, the lower the T2 values.
Conclusion
The T1 and T2 values obtained from the 3D MRF showed a perfect correlation with the gold standard values in the phantom study. Differences in the T1 and T2 values among the different zones of the prostate gland were identified using 3D MRF in patients.
2.Feasibility of Novel Three-Dimensional Magnetic Resonance Fingerprinting of the Prostate Gland:Phantom and Clinical Studies
Dongyeob HAN ; Moon Hyung CHOI ; Young Joon LEE ; Dong-Hyun KIM
Korean Journal of Radiology 2021;22(8):1332-1340
Objective:
To evaluate the feasibility of a new three-dimensional (3D) MR fingerprinting (MRF) technique for the prostate gland by conducting phantom and clinical studies.
Materials and Methods:
The new 3D MRF technique used in this study enables quick data acquisition and has a high resolution. For the phantom study, the MRF T1 and T2 values in an in-house phantom were compared with those of goldstandard mapping methods using linear regression analysis. For the clinical study, we evaluated 90 patients who underwent prostate imaging with MRF for suspected prostate cancer between September 2019 and February 2020. The mean T1 and T2 values were compared in the peripheral zone, transition zone, and focal lesions using paired t tests. The differences in the T1 and T2 values according to cancer aggressiveness were evaluated using one-way analysis of variance.
Results:
In the phantom study, the MRF T1 and T2 values showed a perfect correlation with the gold-standard T1 and T2 values (R > 0.99). In the clinical study, the T1 and T2 values in the peripheral zone were significantly higher than those in the transitional zone (p < 0.001, both). The T1 and T2 values in prostate cancer were significantly lower than those in the peripheral and transitional zones. The higher the grade of cancer, the lower the T2 values.
Conclusion
The T1 and T2 values obtained from the 3D MRF showed a perfect correlation with the gold standard values in the phantom study. Differences in the T1 and T2 values among the different zones of the prostate gland were identified using 3D MRF in patients.
3.High Resolution 3D Magnetic Resonance Fingerprinting with Hybrid Radial-Interleaved EPI Acquisition for Knee Cartilage T1 , T2 Mapping
Dongyeob HAN ; Taehwa HONG ; Yonghan LEE ; Dong-Hyun KIM
Investigative Magnetic Resonance Imaging 2021;25(3):141-155
Purpose:
To develop a 3D magnetic resonance fingerprinting (MRF) method for application in high resolution knee cartilage PD, T1 , T2 mapping.
Materials and Methods:
A novel 3D acquisition trajectory with golden-angle rotating radial in kxy direction and interleaved echo planar imaging (EPI) acquisition in the kz direction was implemented in the MRF framework. A centric order was applied to the interleaved EPI acquisition to reduce Nyquist ghosting artifact due to field inhomogeneity. For the reconstruction, singular value decomposition (SVD) compression method was used to accelerate reconstruction time and conjugate gradient sensitivity-encoding (CG-SENSE) was performed to overcome low SNR of the high resolution data. Phantom experiments were performed to verify the proposed method. In vivo experiments were performed on 6 healthy volunteers and 2 early osteoarthritis (OA) patients.
Results:
In the phantom experiments, the T1 and T2 values of the proposed method were in good agreement with the spin-echo references. The results from the in vivo scans showed high quality proton density (PD), T1 , T2 map with EPI echo train length (NETL = 4), acceleration factor in through plane (Rz = 5), and number of radial spokes (Nspk = 4). In patients, high T2 values (50-60 ms) were seen in all transverse, sagittal, and coronal views and the damaged cartilage regions were in agreement with the hyper-intensity regions shown on conventional turbo spin-echo (TSE) images.
Conclusion
The proposed 3D MRF method can acquire high resolution (0.5 mm3 ) quantitative maps in practical scan time (~ 7 min and 10 sec) with full coverage of the knee (FOV: 160 × 160 × 120 mm3 ).
4.High Resolution 3D Magnetic Resonance Fingerprinting with Hybrid Radial-Interleaved EPI Acquisition for Knee Cartilage T1 , T2 Mapping
Dongyeob HAN ; Taehwa HONG ; Yonghan LEE ; Dong-Hyun KIM
Investigative Magnetic Resonance Imaging 2021;25(3):141-155
Purpose:
To develop a 3D magnetic resonance fingerprinting (MRF) method for application in high resolution knee cartilage PD, T1 , T2 mapping.
Materials and Methods:
A novel 3D acquisition trajectory with golden-angle rotating radial in kxy direction and interleaved echo planar imaging (EPI) acquisition in the kz direction was implemented in the MRF framework. A centric order was applied to the interleaved EPI acquisition to reduce Nyquist ghosting artifact due to field inhomogeneity. For the reconstruction, singular value decomposition (SVD) compression method was used to accelerate reconstruction time and conjugate gradient sensitivity-encoding (CG-SENSE) was performed to overcome low SNR of the high resolution data. Phantom experiments were performed to verify the proposed method. In vivo experiments were performed on 6 healthy volunteers and 2 early osteoarthritis (OA) patients.
Results:
In the phantom experiments, the T1 and T2 values of the proposed method were in good agreement with the spin-echo references. The results from the in vivo scans showed high quality proton density (PD), T1 , T2 map with EPI echo train length (NETL = 4), acceleration factor in through plane (Rz = 5), and number of radial spokes (Nspk = 4). In patients, high T2 values (50-60 ms) were seen in all transverse, sagittal, and coronal views and the damaged cartilage regions were in agreement with the hyper-intensity regions shown on conventional turbo spin-echo (TSE) images.
Conclusion
The proposed 3D MRF method can acquire high resolution (0.5 mm3 ) quantitative maps in practical scan time (~ 7 min and 10 sec) with full coverage of the knee (FOV: 160 × 160 × 120 mm3 ).
6.Susceptibility Weighted Imaging of the Cervical Spinal Cord with Compensation of Respiratory-Induced Artifact
Hongpyo LEE ; Yoonho NAM ; Sung Min GHO ; Dongyeob HAN ; Eung Yeop KIM ; Sheen Woo LEE ; Dong Hyun KIM
Investigative Magnetic Resonance Imaging 2018;22(4):209-217
PURPOSE: The objective of this study was to obtain improved susceptibility weighted images (SWI) of the cervical spinal cord using respiratory-induced artifact compensation. MATERIALS AND METHODS: The artifact from B0 fluctuations by respiration could be compensated using a double navigator echo approach. The two navigators were inserted in an SWI sequence before and after the image readouts. The B0 fluctuation was measured by each navigator echoes, and the inverse of the fluctuation was applied to eliminate the artifact from fluctuation. The degree of compensation was quantified using a quality index (QI) term for compensated imaging using each navigator. Also, the effect of compensation was analyzed according to the position of the spinal cord using QI values. RESULTS: Compensation using navigator echo gave the improved visualization of SWI in cervical spinal cord compared to non-compensated images. Before compensation, images were influenced by artificial noise from motion in both the superior (QI = 0.031) and inferior (QI = 0.043) regions. In most parts of the superior regions, the second navigator resulted in better quality (QI = 0.024, P < 0.01) compared to the first navigator, but in the inferior regions the first navigator showed better quality (QI = 0.033, P < 0.01) after correction. CONCLUSION: Motion compensation using a double navigator method can increase the improvement of the SWI in the cervical spinal cord. The proposed method makes SWI a useful tool for the diagnosis of spinal cord injury by reducing respiratory-induced artifact.
Artifacts
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Cervical Cord
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Compensation and Redress
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Diagnosis
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Methods
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Noise
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Qi
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Respiration
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Spinal Cord
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Spinal Cord Injuries
7.Prostate gland volume estimation: anteroposterior diameters measured on axial versus sagittal ultrasonography and magnetic resonance images
Seo Yeon YOON ; Moon Hyung CHOI ; Young Joon LEE ; Robert GRIMM ; Heinrich VON BUSCH ; Dongyeob HAN ; Yohan SON ; Bin LOU ; Ali KAMEN
Ultrasonography 2023;42(1):154-164
Purpose:
The aim of this study was to evaluate the accuracy of prostate volume estimates calculated from the ellipsoid formula using the anteroposterior (AP) diameter measured on axial and sagittal images obtained through ultrasonography (US) and magnetic resonance imaging (MRI).
Methods:
This retrospective study included 456 patients with transrectal US and MRI from two university hospitals. Two radiologists independently measured the prostate gland diameters on US and MRI: AP diameters on axial and sagittal images, transverse, and longitudinal diameters on midsagittal images. The volume estimates, volumeax and volumesag, were calculated from the ellipsoid formula by using the AP diameter on axial and sagittal images, respectively. The prostate volume extracted from MRI-based whole-gland segmentation was considered the gold standard. The intraclass correlation coefficient (ICC) was used to evaluate the inter-method agreement between volumeax and volumesag, and agreement with the gold standard. The Wilcoxon signedrank test was used to analyze the differences between the volume estimates and the gold standard.
Results:
The prostate gland volume estimates showed excellent inter-method agreement, and excellent agreement with the gold standard (ICCs >0.9). Compared with the gold standard, the volume estimates were significantly larger on MRI and significantly smaller on US (P<0.001). The volume difference (segmented volume–volume estimate) was greater in patients with larger prostate glands, especially on US.
Conclusion
Volumeax and volumesag showed excellent inter-method agreement and excellent agreement with the gold standard on both US and MRI. However, prostate volume was overestimated on MRI and underestimated on US.