Refaat E Gabr1, Khader M Hasan2, Muhammad E Haque3, Flavia M Nelson3, Jerry S Wolinsky3, Ponnada A Narayana2. 1. Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA. refaat.e.gabr@uth.tmc.edu. 2. Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA. 3. Department of Neurology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA.
Abstract
PURPOSE: Postacquisition combination of three-dimensional T2-weighted (T2w) and fluid-attenuated inversion recovery (FLAIR) images can improve the visualization of brain lesions in multiple sclerosis (MS). However, an optimal way to combine these images has not been described so far. The main objective of this study is to investigate an optimal combination of T2w and FLAIR to improve the conspicuity of MS lesions. MATERIALS AND METHODS: We determined the parameters for a generalized multiplicative image combination which maximize the contrast-to-noise ratio (CNR) between lesions and normal-appearing brain tissue through simulations and verified experimentally. MRI data from 11 MS patients acquired at 3 Tesla were retrospectively analyzed using the proposed approach and compared with conventional FLAIR, and to images obtained by direct multiplication of T2w and FLAIR (FLAIR2 ). Image quality was assessed by region-of-interest analysis. In addition, to evaluate the degree of cerebrospinal fluid (CSF) suppression, CSF-to-gray matter (CSF/GM) ratio was calculated. Reduction in global image contrast was assessed by computing the reduction in the contrast of mid-level intensity values. RESULTS: An optimal combination was found to be the third order expression: FLAIR3 = FLAIR1.55 × T2w1.45 . Compared with FLAIR, the lesion CNR was significantly increased by 1.9× (P < 0.005) and 2.5× (P < 0.001) using FLAIR2 and FLAIR3 , respectively. CSF/GM ratio was increased by 1.7× in FLAIR2 (P < 0.001) compared with FLAIR, while it was reduced to 0.7× on FLAIR3 (P < 0.05). The mid-intensity contrast was preserved on FLAIR2 (P = 0.2), and decreased by 29% on FLAIR3 (P < 0.001). CONCLUSION: These results show that the optimized combination of FLAIR and T2w can improve MS lesion conspicuity. J. Magn. Reson. Imaging 2016;44:1293-1300.
PURPOSE: Postacquisition combination of three-dimensional T2-weighted (T2w) and fluid-attenuated inversion recovery (FLAIR) images can improve the visualization of brain lesions in multiple sclerosis (MS). However, an optimal way to combine these images has not been described so far. The main objective of this study is to investigate an optimal combination of T2w and FLAIR to improve the conspicuity of MS lesions. MATERIALS AND METHODS: We determined the parameters for a generalized multiplicative image combination which maximize the contrast-to-noise ratio (CNR) between lesions and normal-appearing brain tissue through simulations and verified experimentally. MRI data from 11 MS patients acquired at 3 Tesla were retrospectively analyzed using the proposed approach and compared with conventional FLAIR, and to images obtained by direct multiplication of T2w and FLAIR (FLAIR2 ). Image quality was assessed by region-of-interest analysis. In addition, to evaluate the degree of cerebrospinal fluid (CSF) suppression, CSF-to-gray matter (CSF/GM) ratio was calculated. Reduction in global image contrast was assessed by computing the reduction in the contrast of mid-level intensity values. RESULTS: An optimal combination was found to be the third order expression: FLAIR3 = FLAIR1.55 × T2w1.45 . Compared with FLAIR, the lesion CNR was significantly increased by 1.9× (P < 0.005) and 2.5× (P < 0.001) using FLAIR2 and FLAIR3 , respectively. CSF/GM ratio was increased by 1.7× in FLAIR2 (P < 0.001) compared with FLAIR, while it was reduced to 0.7× on FLAIR3 (P < 0.05). The mid-intensity contrast was preserved on FLAIR2 (P = 0.2), and decreased by 29% on FLAIR3 (P < 0.001). CONCLUSION: These results show that the optimized combination of FLAIR and T2w can improve MS lesion conspicuity. J. Magn. Reson. Imaging 2016;44:1293-1300.
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Authors: Refaat E Gabr; Getaneh B Tefera; William J Allen; Amol S Pednekar; Ponnada A Narayana Journal: Int J Comput Assist Radiol Surg Date: 2016-10-28 Impact factor: 2.924
Authors: R E Gabr; J A Lincoln; A Kamali; O Arevalo; X Zhang; X Sun; K M Hasan; P A Narayana Journal: AJNR Am J Neuroradiol Date: 2020-10-08 Impact factor: 3.825
Authors: William J Allen; Refaat E Gabr; Getaneh B Tefera; Amol S Pednekar; Matthew W Vaughn; Ponnada A Narayana Journal: IEEE J Biomed Health Inform Date: 2018-03 Impact factor: 5.772
Authors: Refaat E Gabr; Amol S Pednekar; Arash Kamali; John A Lincoln; Flavia M Nelson; Jerry S Wolinsky; Ponnada A Narayana Journal: Magn Reson Med Date: 2018-01-15 Impact factor: 4.668