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245. A protocol set-up for fast brain T1 mapping of subcortical tissues
Abstracts / Physica Medica 56 (2018) 133–278
reduction of GTV compared with MRI. The automatic adaptive thresholding delineation method may provide robust and reliable tool to help physician in segmenting PET images, reducing interand intra-observer variability. https://doi.org/10.1016/j.ejmp.2018.04.255
245. A protocol set-up for fast brain T1 mapping of subcortical tissues E. Belligotti a, L. Mascaro b, C. Ambrosi c, C. Pinardi d, M. Reali e, R. Lucchini f, C. Ying Tang f, R. Gasparotti e a
A.O. Ospedali Riuniti Marche Nord, Medical Physics Unit, Pesaro, Italy b ASST Spedali Civili, Medical Physics Unit, Brescia, Italy c ASST Spedali Civili, Neuroradiology Unit, Brescia, Italy d University of Parma, Department of Medical and Surgical Specialties, Parma, Italy e University of Brescia, Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Brescia, Italy f Ichan School of Medicine at Mount Sinai, New York, USA Purpose. This work is part of a larger cohort study aimed at investigating the long term effects of exposure to manganese [1]. In this study we set up a protocol for brain fast T1 mapping and segmentation of subcortical tissues, in particular globus pallidus (GP), that is reported to be a target tissue for manganese deposition in brain. Methods. The variable flip angle model was used for T1 mapping. Acquisition protocol, set up on a 3T Siemens Skyra MR system, includes 10 RF spoiled 3D gradient echoes (VIBE) with flip angles from 2° to 30° and a reduced scanned volume to cover GP in the shortest possible time, an extra 30° VIBE covering the whole brain (WB- VIBE), two fast acquisitions with different TEs for B1 map calculation, used to correct nominal flip angles, and a 3D-MPRAGE acquisition of the whole brain with the same WB-WIBE geometry. T1 and error maps were calculated offline with a bespoke Matlab script, checking accuracy with calibrated gels. The most efficient pipeline for post-processing, shown in Fig. 1, is as follows: T1 map calculation of the reduced volume, and zero padding of the missing slices to get the same WB-VIBE volume (WB-T1MAP); 3D-MPRAGE and WB-T1MAP coregistration using the WB-VIBE to 3D transformation matrix (WB-T1MAP-COR); GP automatic segmentation of the 3D-MPRAGE and, with the output mask, GP statistics calculation of the WB-T1MAP-COR. In order to cancel possible partial volume
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effects, segmented regions were eroded by 1 pixels and T1 results were compared. The protocol was checked on a group of 10 adolescents that were exposed to Mn during childhood. Results. T1 accuracy was 4.3% (median) and within 13.8% (interquartile distance). GP-T1 average values were 1314,65 ms and 1302,92 ms after erosion, close to the values reported in other papers, with a coefficient of variation respectively decreased from 6.8%, to 5.6%. Conclusions. We set up a fast and automated T1 mapping protocol with good accuracy and optimised data variability in vivo.
Reference 1. Lucchini R, Guazzetti S, Zoni S, et al.. Tremor, olfactory and motor changes in italian adolescents exposed to historical ferromanganese emission. Neurotoxicology 2012;33(4):687–96. https://doi.org/10.1016/j.ejmp.2018.04.256
246. Analysis of signal-to-noise ratio for a 2-channels coil developed to enable transcranial Magnetic Resonance-guided Focused Ultrasound Surgery (tcMRgFUS) with 1.5 T MRI scanners M. Marrale a, G. Collura a,b, A. Napoli c, L. Geraci a, C. Catalano c, M. Midiri b, R. Lagalla b, C. Gagliardo b a Department of Physics and Chemistry, University of Palermo, Palermo, Italy b Section of Radiological Sciences, Department of Biopathology and Medical Biotechnologies, University of Palermo, Palermo, Italy c Radiology Section, Department of Radiological, Oncological and Anatomopathological Sciences, ‘‘Sapienza” University of Rome, Rome, Italy
Purpose. In recent years trans-cranial Magnetic Resonance-guided Focused Ultrasound Surgery (tcMRgFUS) treatments have aroused large scientific and medical interest [1]. Usually, tcMRgFUS systems are integrated with 3 T systems which allow the use of the body RF coil for both real time imaging and MR-thermometry. At University Hospital of Palermo there is the world-first installation of a tcMRgFUS system integrated with a 1.5 T scanner. Here we present the characterization in terms of signal-to-noise ratio (SNR) of a dedicated RF coils suitably developed (by InSightec) to enable tcMRgFUS treatments with 1.5 T MR units.
Figure 1: image post-processing pipeline
reduction of GTV compared with MRI. The automatic adaptive thresholding delineation method may provide robust and reliable tool to help physician in segmenting PET images, reducing interand intra-observer variability. https://doi.org/10.1016/j.ejmp.2018.04.255
245. A protocol set-up for fast brain T1 mapping of subcortical tissues E. Belligotti a, L. Mascaro b, C. Ambrosi c, C. Pinardi d, M. Reali e, R. Lucchini f, C. Ying Tang f, R. Gasparotti e a
A.O. Ospedali Riuniti Marche Nord, Medical Physics Unit, Pesaro, Italy b ASST Spedali Civili, Medical Physics Unit, Brescia, Italy c ASST Spedali Civili, Neuroradiology Unit, Brescia, Italy d University of Parma, Department of Medical and Surgical Specialties, Parma, Italy e University of Brescia, Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Brescia, Italy f Ichan School of Medicine at Mount Sinai, New York, USA Purpose. This work is part of a larger cohort study aimed at investigating the long term effects of exposure to manganese [1]. In this study we set up a protocol for brain fast T1 mapping and segmentation of subcortical tissues, in particular globus pallidus (GP), that is reported to be a target tissue for manganese deposition in brain. Methods. The variable flip angle model was used for T1 mapping. Acquisition protocol, set up on a 3T Siemens Skyra MR system, includes 10 RF spoiled 3D gradient echoes (VIBE) with flip angles from 2° to 30° and a reduced scanned volume to cover GP in the shortest possible time, an extra 30° VIBE covering the whole brain (WB- VIBE), two fast acquisitions with different TEs for B1 map calculation, used to correct nominal flip angles, and a 3D-MPRAGE acquisition of the whole brain with the same WB-WIBE geometry. T1 and error maps were calculated offline with a bespoke Matlab script, checking accuracy with calibrated gels. The most efficient pipeline for post-processing, shown in Fig. 1, is as follows: T1 map calculation of the reduced volume, and zero padding of the missing slices to get the same WB-VIBE volume (WB-T1MAP); 3D-MPRAGE and WB-T1MAP coregistration using the WB-VIBE to 3D transformation matrix (WB-T1MAP-COR); GP automatic segmentation of the 3D-MPRAGE and, with the output mask, GP statistics calculation of the WB-T1MAP-COR. In order to cancel possible partial volume
213
effects, segmented regions were eroded by 1 pixels and T1 results were compared. The protocol was checked on a group of 10 adolescents that were exposed to Mn during childhood. Results. T1 accuracy was 4.3% (median) and within 13.8% (interquartile distance). GP-T1 average values were 1314,65 ms and 1302,92 ms after erosion, close to the values reported in other papers, with a coefficient of variation respectively decreased from 6.8%, to 5.6%. Conclusions. We set up a fast and automated T1 mapping protocol with good accuracy and optimised data variability in vivo.
Reference 1. Lucchini R, Guazzetti S, Zoni S, et al.. Tremor, olfactory and motor changes in italian adolescents exposed to historical ferromanganese emission. Neurotoxicology 2012;33(4):687–96. https://doi.org/10.1016/j.ejmp.2018.04.256
246. Analysis of signal-to-noise ratio for a 2-channels coil developed to enable transcranial Magnetic Resonance-guided Focused Ultrasound Surgery (tcMRgFUS) with 1.5 T MRI scanners M. Marrale a, G. Collura a,b, A. Napoli c, L. Geraci a, C. Catalano c, M. Midiri b, R. Lagalla b, C. Gagliardo b a Department of Physics and Chemistry, University of Palermo, Palermo, Italy b Section of Radiological Sciences, Department of Biopathology and Medical Biotechnologies, University of Palermo, Palermo, Italy c Radiology Section, Department of Radiological, Oncological and Anatomopathological Sciences, ‘‘Sapienza” University of Rome, Rome, Italy
Purpose. In recent years trans-cranial Magnetic Resonance-guided Focused Ultrasound Surgery (tcMRgFUS) treatments have aroused large scientific and medical interest [1]. Usually, tcMRgFUS systems are integrated with 3 T systems which allow the use of the body RF coil for both real time imaging and MR-thermometry. At University Hospital of Palermo there is the world-first installation of a tcMRgFUS system integrated with a 1.5 T scanner. Here we present the characterization in terms of signal-to-noise ratio (SNR) of a dedicated RF coils suitably developed (by InSightec) to enable tcMRgFUS treatments with 1.5 T MR units.
Figure 1: image post-processing pipeline