Publications

2017
P Aksit Ciris, C-C Cheng, C-S Mei, LP Panych, and B Madore. 12/2017. “Dual-Pathway sequences for MR thermometry: When and where to use them.” Magn Reson Med, 77, 3, Pp. 1193–1200.Abstract
PURPOSE: Dual-pathway sequences have been proposed to help improve the temperature-to-noise ratio (TNR) in MR thermometry. The present work establishes how much of an improvement these so-called "PSIF-FISP" sequences may bring in various organs and tissues. METHODS: Simulations and TNR calculations were validated against analytical equations, phantom, abdomen, and brain scans. Relative TNRs for PSIF-FISP, as compared to a dual-FISP reference standard, were calculated for flip angle (FA) = 1 to 85 º and repetition time (TR) = 6 to 60 ms, for gray matter, white matter, cervix, endometrium, myometrium, prostate, kidney medulla and cortex, bone marrow, pancreas, spleen, muscle, and liver tissues. RESULTS: PSIF-FISP was TNR superior in the kidney, pelvis, spleen, or gray matter at most tested TR and FA settings, and benefits increased at shorter TRs. PSIF-FISP was TNR superior in other tissues, e.g., liver, muscle, pancreas, for only short TR settings (20 ms or less). The TNR benefits of PSIF-FISP increased slightly with FA, and strongly with decreasing TR. Up to two- to three-fold reductions in TR with 20% TNR gains were achievable. In any given tissue, TNR performance is expected to further improve with heating, due to changes in relaxation rates. CONCLUSION: Dual-pathway PSIF-FISP can improve TNR and acquisition speed over standard gradient-recalled echo sequences, but optimal acquisition parameters are tissue dependent. Magn Reson Med 77:1193-1200, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
T-C Chao, Jr-y Chiou, SE Maier, and B Madore. 12/2017. “Fast diffusion imaging with high angular resolution.” Magn Reson Med, 77, 2, Pp. 696–706.Abstract
PURPOSE: High angular resolution diffusion imaging (HARDI) is a well-established method to help reveal the architecture of nerve bundles, but long scan times and geometric distortions inherent to echo planar imaging (EPI) have limited its integration into clinical protocols. METHODS: A fast imaging method is proposed here that combines accelerated multishot diffusion imaging (AMDI), multiplexed sensitivity encoding (MUSE), and crossing fiber angular resolution of intravoxel structure (CFARI) to reduce spatial distortions and reduce total scan time. A multishot EPI sequence was used to improve geometrical fidelity as compared to a single-shot EPI acquisition, and acceleration in both k-space and diffusion sampling enabled reductions in scan time. The method is regularized and self-navigated for motion correction. Seven volunteers were scanned in this study, including four with volumetric whole brain acquisitions. RESULTS: The average similarity of microstructural orientations between undersampled datasets and their fully sampled counterparts was above 85%, with scan times below 5 min for whole-brain acquisitions. Up to 2.7-fold scan time acceleration along with four-fold distortion reduction was achieved. CONCLUSION: The proposed imaging strategy can generate HARDI results with relatively good geometrical fidelity and low scan duration, which may help facilitate the transition of HARDI from a successful research tool to a practical clinical one. Magn Reson Med 77:696-706, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
P Aksit Ciris, Jr-y Chiou, D Glazer, SH Zhang, T-C Chao, B Madore, and SE Maier. 2017. “Accelerated segmented diffusion-weighted prostate imaging for higher resolution, higher geometric fidelity, and multi-b perfusion quantification.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: p. 0112.
C-S Mei, B Madore, S Zong, P-H Wu, GR Cosgrove, and McDannold NJ. 2017. “Focus Correction in MR thermography for Precise Targeting in Focused Ultrasound Thalamotomy for Essential Tremor.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: 1176.
F Preiswerk, M Toews, C-C Cheng, Jr-y Chiou, C-S Mei, L. Schaefer, W. S. Hoge, B Schwartz, LP Panych, and B Madore. 2017. “Hybrid MRI-Ultrasound Acquisitions, and Scannerless Real-Time Imaging.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: p. 0033.
P-H Wu, F Preiswerk, C-C Cheng, and B Madore. 2017. “Hybrid MR-ultrasound acquisition for multi-baseline thermometry.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: 2587.
C-C Cheng, W. S. Hoge, T-H Kuo, and B Madore. 2017. “Quantitative MRI method, a multi-pathway multi-echo approach.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: p. 5044.
F Preiswerk, J Cai, C-C Cheng, W. S. Hoge, P-H Wu, LP Panych, and B Madore. 2017. “RF-sensing for Trigger-based Synchronization of Auxiliary Devices, and Pulse-sequence Debugging.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: p. 4444.
C-L Chang, Jr-y Chiou, M-L Wu, S-Y Tsai, SE Maier, B Madore, and T-C Chao. 2017. “To accelerate or not: An Investigation on the Tractography-based Diffusion Features for Fast Diffusion Imaging with High Angular Resolution.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: p. 3349.
WS Hoge, F Preiswerk, JR Polimeni, SS Yengul, P Aksit Ciris, and B Madore. 2017. “Ultrasound Monitoring of a Respiratory Phantom for the Development and Validation of Segmented EPI Reconstruction Methods.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: p. 1307.
F Preiswerk, C-C Cheng, P-H Wu, LP Panych, and B Madore. 2017. “Ultrasound-based cardiac gating for MRI.” Proceedings of the International Society of Magnetic Resonance in Medicine. Honolulu, USA: p. 4443.
2016
C-C Cheng, C-S Mei, J Duryea, H-W Chung, T-C Chao, LP Panych, and B Madore. 12/2016. “Dual-pathway multi-echo sequence for simultaneous frequency and T2 mapping.” J Magn Reson, 265, Pp. 177-87.Abstract
PURPOSE: To present a dual-pathway multi-echo steady state sequence and reconstruction algorithm to capture T2, T2( *) and field map information. METHODS: Typically, pulse sequences based on spin echoes are needed for T2 mapping while gradient echoes are needed for field mapping, making it difficult to jointly acquire both types of information. A dual-pathway multi-echo pulse sequence is employed here to generate T2 and field maps from the same acquired data. The approach might be used, for example, to obtain both thermometry and tissue damage information during thermal therapies, or susceptibility and T2 information from a same head scan, or to generate bonus T2 maps during a knee scan. RESULTS: Quantitative T2, T2( *) and field maps were generated in gel phantoms, ex vivo bovine muscle, and twelve volunteers. T2 results were validated against a spin-echo reference standard: A linear regression based on ROI analysis in phantoms provided close agreement (slope/R(2)=0.99/0.998). A pixel-wise in vivo Bland-Altman analysis of R2=1/T2 showed a bias of 0.034 Hz (about 0.3%), as averaged over four volunteers. Ex vivo results, with and without motion, suggested that tissue damage detection based on T2 rather than temperature-dose measurements might prove more robust to motion. CONCLUSION: T2, T2( *) and field maps were obtained simultaneously, from the same datasets, in thermometry, susceptibility-weighted imaging and knee-imaging contexts.
J Duryea, C Cheng, LF Schaefer, S. Smith, and B Madore. 12/2016. “Integration of accelerated MRI and post-processing software: a promising method for studies of knee osteoarthritis.” Osteoarthritis CartilageOsteoarthritis Cartilage, 24, Pp. 1905-1909.Abstract
OBJECTIVE: Magnetic resonance imaging (MRI) is a widely used imaging modality for studies of knee osteoarthritis (OA). Compared to radiography, MRI offers exceptional soft tissue imaging and true three-dimensional (3D) visualization. However, MRI is expensive both due to the cost of acquisition and evaluation of the images. The goal of our study is to develop a new method to address the cost of MRI by combining innovative acquisition methods and automated post-processing software. METHODS: Ten healthy volunteers were scanned with three different MRI protocols: A standard 3D dual-echo steady state (DESS) pulse sequence, an accelerated DESS (DESSAcc), acquired at approximately half the time compared to DESS, and a multi-echo time DESS (DESSMTE), which is capable of producing measurements of T2 relaxation time. A software tool was used to measure cartilage volume. Accuracy was quantified by comparing DESS to DESSAcc and DESSMTE and precision was measured using repeat readings and acquisitions. T2 precision was determined using duplicate DESSMTE acquisitions. Intra-class correlation coefficients (ICCs), root-mean square standard deviation (RMSSD), and the coefficient of variation (CoV) were used to quantify accuracy and precision. RESULTS: The accuracies of DESSAcc and DESSMTE were CoV = 3.7% and CoV = 6.6% respectively, while precision was 3.8%, 3.0%, and 3.1% for DESS, DESSAcc and DESSMTE. T2 repositioning precision was 5.8%. CONCLUSION: The results demonstrate that accurate and precise quantification of cartilage volume is possible using a combination of substantially faster MRI acquisition and post-processing software. Precise measurements of cartilage T2 and volume can be made using the same acquisition.
P Aksit Ciris, Jr-y Chiou, A Fedorov, CM Tempany-Afdhal, B Madore, and SE Maier. 2016. “Accelerated Segmented Diffusion-Weighted Prostate Imaging for Higher Resolution.” Proceedings of the International Society of Magnetic Resonance in Medicine. Singapore: p. 3860.
P Aksit Ciris, C-C Cheng, C-S Mei, LP Panych, and B Madore. 2016. “Dual-pathway sequences for MR thermometry: When and where to use them.” Proceedings of the International Society of Magnetic Resonance in Medicine. Singapore: p. 3001.
F Preiswerk, C-C Cheng, SS Yengul, LP Panych, and B Madore. 2016. “Scanner-less real-time MRI.” Proceedings of the International Society of Magnetic Resonance in Medicine. Singapore: p. 3578.
C-C Cheng, LF Schaefer, J Duryea, and B Madore. 2016. “Simultaneous DESS imaging and T2 mapping, for knee osteoarthritis studies.” Proceedings of the International Society of Magnetic Resonance in Medicine. Singapore: p. 700.
SS Yengul, B Madore, and PE Barbone. 2016. “Toward validation for shear wave elastography using torsional vibration rheometry in soft gels.” Proceedings of the Fifteenth International Tissue Elasticity Conference.
SS Yengul, B Madore, and PE Barbone. 2016. “Toward validation of shear wave elastography using vibration rheometry in soft gels.” The Journal of the Acoustical Society of America 139 (4), Pp. 2027–2027. ASA.
2015
C-S Mei, R Chu, W. S. Hoge, LP Panych, and B Madore. 12/2015. “Accurate field mapping in the presence of B0 inhomogeneities, applied to MR thermometry.” Magn Reson Med, 73, 6, Pp. 2142–2151.Abstract
PURPOSE: To describe how B0 inhomogeneities can cause errors in proton resonance frequency (PRF) shift thermometry, and to correct for these errors. METHODS: With PRF thermometry, measured phase shifts are converted into temperature measurements through the use of a scaling factor proportional to the echo time, TE. However, B0 inhomogeneities can deform, spread, and translate MR echoes, potentially making the "true" echo time vary spatially within the imaged object and take on values that differ from the prescribed TE value. Acquisition and reconstruction methods able to avoid or correct for such errors are presented. RESULTS: Tests were performed in a gel phantom during sonication, and temperature measurements were made with proper shimming as well as with intentionally introduced B0 inhomogeneities. Errors caused by B0 inhomogeneities were observed, described, and corrected by the proposed methods. No statistical difference was found between the corrected results and the reference results obtained with proper shimming, while errors by more than 10% in temperature elevation were corrected for. The approach was also applied to an abdominal in vivo dataset. CONCLUSION: Field variations induce errors in measured field values, which can be detected and corrected. The approach was validated for a PRF thermometry application.

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