title: Early metabolic changes following ischemia onset in rats: an in vivo diffusion-weighted imaging and 1H-magnetic resonance spectroscopy study at 7.0 T.
abstract: Despite improvements in imaging techniques, it remains challenging to quantitatively assess the time of ischemic onset of an acute ischemic stroke. It is crucial to evaluate the early signs of infarction, which are predictive of responses to recombinant tissue plasminogen activator within a treatment window of 4.5 h after stroke induction. The aim of the present study was to assess and quantify the onset time for hyperacute middle cerebral artery occlusion (MCAO) ischemic stroke by measuring the apparent diffusion coefficient (ADC) of diffusion‑weighted imaging (DWI) and 1H‑magnetic resonance spectroscopy (MRS) at 7.0 T. DWI, conventional T2‑weighted imaging (T2WI) and subsequent focal ADCs were employed to evaluate ischemic brain lesions in a rat model of MCAO (n=20) at different time‑points following a stroke. A quantitation of local changes in metabolite concentrations within the lesions was performed using MRS. Proton metabolites were quantified automatically using LCModel software. At 30 min after MCAO, intense signals were observed in the DWI spectra of all animals. No abnormal signal was observed within 3 h by T2WI. ADC images of the central area, peripheral striping and on the fringes of the infarction demonstrated a lower signal than that of the normal side. The ADC decreased significantly within 30 min after infarction, followed by a gradual elevation in volatility levels and then becoming relatively stable at a lower level 3 h later. MRS exhibited a consistent elevation of lactate and reduced N‑acetyl aspartic acid. Glutamate and taurine reached a maximum 2 h after MCAO and began to decrease 1 h later. In conclusion, the present study demonstrated that hyperacute ischemic stroke can be quantitatively detected with the application of ADC, DWI and MRS. These methods may also be used to quantitatively assess the ischemic onset time of a hyperacute stroke.
authors: Department of Radiology, Affiliated Hospital, Jiangnan University, Wuxi, Jiangsu 214062, P.R. China.
authors: Gen
authors: G
authors: Yan
authors: Department of Radiology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors: Zhuozhi
authors: Z
authors: Dai
authors: Department of Basic Medicine, Jiangnan University Medical School, Wuxi, Jiangsu 214122, P.R. China.
authors: Yinghua
authors: Y
authors: Xuan
authors: Department of Radiology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors: Renhua
authors: R
authors: Wu
mesh_terms: D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000378:metabolism* / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging; D020244:Infarction, Middle Cerebral Artery / Q000378:metabolism* / Q000473:pathology*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
references: Neurology. 1996 Aug;47(2):366-75
references: 8757006
references: Stroke. 2003 Nov;34(11):2729-35
references: 14576370
references: Stroke. 1998 May;29(5):1048-56; discussion 1056-7
references: 9596256
references: J Cereb Blood Flow Metab. 1998 Jun;18(6):583-609
references: 9626183
references: MAGMA. 1999 May;8(2):98-108
references: 10456372
references: Stroke. 2005 Jan;36(1):66-73
references: 15569863
references: Stroke. 2005 May;36(5):980-5
references: 15790950
references: Korean J Radiol. 2005 Apr-Jun;6(2):64-74
references: 15968144
references: J Cereb Blood Flow Metab. 2006 Nov;26(11):1451-62
references: 16538230
references: Circulation. 2007 May 22;115(20):e478-534
references: 17515473
references: Stroke. 2009 Mar;40(3):767-72
references: 19150873
references: Stroke. 2011 Mar;42(3):799-805
references: 21293024
references: Stroke. 2013 Mar;44(3):870-947
references: 23370205
references: Radiology. 1986 Nov;161(2):401-7
references: 3763909
references: Neurology. 1987 Oct;37(10):1580-5
references: 3658160
references: Stroke. 1989 Jan;20(1):84-91
references: 2643202
references: J Cereb Blood Flow Metab. 1993 Jan;13(1):88-97
references: 8093250
references: Ann Neurol. 1995 Feb;37(2):231-41
references: 7847864
references: Stroke. 1995 May;26(5):807-12
references: 7740571
references: J Endod. 1995 Jul;21(7):391-3
references: 7499982
references: AJNR Am J Neuroradiol. 1996 May;17(5):873-86
references: 8733962
references: Korean J Radiol. 2013 Mar-Apr;14(2):307-15
references: 23482695
references: Stroke. 2000 Aug;31(8):1965-72; discussion 1972-3
references: 10926965
references: NMR Biomed. 2001 Jun;14(4):260-4
references: 11410943
references: Ann Neurol. 2002 Jul;52(1):20-8
references: 12112043
references: Radiology. 1997 Nov;205(2):327-33
references: 9356611