Tomoyuki Okuaki1, Yukihisa Takayama2, Akihiro Nishie3, Tetsuo Ogino4, Makoto Obara4, Hiroshi Honda3, Tosiaki Miyati5, Marc Van Cauteren6. 1. Philips Healthcare, Tokyo, Japan; Division of Health Science, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan. Electronic address: tomoyuki.okuaki@philips.com. 2. Department of Radiology Informatics and Network, Kyushu University, Graduate School of Medical Sciences, Fukuoka, Japan. 3. Department of Clinical Radiology, Kyushu University, Graduate School of Medical Sciences, Fukuoka, Japan. 4. Philips Electronics Japan, Tokyo, Japan. 5. Division of Health Science, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan. 6. Philips Healthcare, Tokyo, Japan.
Abstract
PURPOSE: The purpose of this study is to investigate the performance of stretched-type adiabatic spin lock pulses for homogeneous spin locking with a flexible spin lock time (TSL) setting. METHODS: T1ρ values were obtained from 61 patients and five normal volunteers who were categorized using the Child-Pugh classification and scanned using each spin lock pulse type. The pulses used were the block and two kinds of hyperbolic secant (HS); HS8_10, and HS8_5. Visual scoring was categorized using a four point scale (1:Severe, 2:Moderate, 3:Mild and 4:None) to evaluate the homogeneity of the T1ρ map and the source images obtained by each spin lock pulse. Mean T1ρ values among the patient groups with different Child-Pugh classification were compared. RESULTS: The visual assessment scores were 1.98 ± 1.05 for block pulse locking, 3.87 ± 0.39 for HS8_10 pulse locking, and 3.83 ± 0.45 for HS8_5 pulse locking, respectively. The scores between block pulse and HS8_10 were significantly different (p < 0.001), as were those between block pulse and HS8_5 (p < 0.001). The median T1ρ values of normal liver function, Child-Pugh A, and Child-Pugh B or C were 37.00 ms, 40.77 ms, and 42.20 ms for block pulse, 46.75 ms, 50.78 ms, and 55.60 ms for HS8_10, and 48.80 ms, 55.42 ms, and 57.80 ms for HS8_5, respectively. CONCLUSION: The spin locking sequence using stretched-type adiabatic pulses provides homogeneous liver T1ρ maps with reduced artifact and is necessary for a robust evaluation of liver function using T1ρ.
PURPOSE: The purpose of this study is to investigate the performance of stretched-type adiabatic spin lock pulses for homogeneous spin locking with a flexible spin lock time (TSL) setting. METHODS: T1ρ values were obtained from 61 patients and five normal volunteers who were categorized using the Child-Pugh classification and scanned using each spin lock pulse type. The pulses used were the block and two kinds of hyperbolic secant (HS); HS8_10, and HS8_5. Visual scoring was categorized using a four point scale (1:Severe, 2:Moderate, 3:Mild and 4:None) to evaluate the homogeneity of the T1ρ map and the source images obtained by each spin lock pulse. Mean T1ρ values among the patient groups with different Child-Pugh classification were compared. RESULTS: The visual assessment scores were 1.98 ± 1.05 for block pulse locking, 3.87 ± 0.39 for HS8_10 pulse locking, and 3.83 ± 0.45 for HS8_5 pulse locking, respectively. The scores between block pulse and HS8_10 were significantly different (p < 0.001), as were those between block pulse and HS8_5 (p < 0.001). The median T1ρ values of normal liver function, Child-Pugh A, and Child-Pugh B or C were 37.00 ms, 40.77 ms, and 42.20 ms for block pulse, 46.75 ms, 50.78 ms, and 55.60 ms for HS8_10, and 48.80 ms, 55.42 ms, and 57.80 ms for HS8_5, respectively. CONCLUSION: The spin locking sequence using stretched-type adiabatic pulses provides homogeneous liver T1ρ maps with reduced artifact and is necessary for a robust evaluation of liver function using T1ρ.
Authors: Silvia Mangia; Alena Svatkova; Daniele Mascali; Mikko J Nissi; Philip C Burton; Petr Bednarik; Edward J Auerbach; Federico Giove; Lynn E Eberly; Michael J Howell; Igor Nestrasil; Paul J Tuite; Shalom Michaeli Journal: Front Neurosci Date: 2017-12-19 Impact factor: 4.677