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Functional brain activation after stroke—a PET-fMRI comparison
NemoImage
11, Number
5, 2000, Part 2 of 2 Parts 1 D E )r;L@
METHODS
- ACQUISITION
Functional brain activation after stroke-a
PET-fMFU comparison
Gilbert Wunderlich*t, Gereon R. Fink*?, Peter H. Weiss?, Nadhu J. Shah?, Haus Hem&, Karl Zillest+, Riidiger J. Se&*, Hans-J. Freund* *Neurologische Klinik, Heinrich-Heine-Universitiit
Diisseldorf
tlnstitut fiir Medizin, Forschungszentncm Jiilich SC&O. Vogt lnstitut fiir Hirnforschung, Heinrich-Heine-Universitiit
Diisseldod
Germany
Introduction PET using “0-butanol or water is frequently used to map motor reorganization after hemiparetic stroke in the subacute and chronic phase (1,2,3). More recently, fMRI has been applied on this purpose (4), although this is criticized for a pctential influence of neurovascular decoupling following ischemic brain injury on the BOLD response depicted by EPI imaging. Using PET and fMR1. we here explore this methodological issue by comparing the pattern of activations depicted during unilateral and bilateral ipsi- and contralesional hand movements in patients with a first ischemic stroke and impaired hand function. Subjects
and Methods
Six patients (39-72 ys, five male, one female) with acute infarctions in the middle cerebral artery territory located around the central sulcus in five patients and striatocapsular in one patient were studied. PET and fMRI were carried out on the same day following oral and written informed consent. All were examined between five and 10 days after stroke and five out of six patients had made good recovery during this time with near to normal hand function. PET and fMR1 measurements were performed during rest (baseline) and three different motor tasks: (i) repetitive opening and closing of the unaffected hand, (ii) repetitive opening and closing of the affected hand, and (iii) repetitive opening and closing of the both hands in phase. PET studies were performed on a CIYSIEMENS ECAT EXACT HR camera in 3D mode with three replications per condition. For fMR1 a 1.5T Siemens Magnetom Vision was used. The fMR1 paradigm consisted of a preceding baseline of 30 s (6 x TR, not used for statistical analysis) followed by six repetitions of a cycle with 45 s activation period (9 TR) and a 45 s (9 TR) rest = baseline period (to separate the experimental conditions from one another). Sequence parameters were: Gradient-echo EPI, TE = 66 ms, TR = 5 s, flip angle = 90”, slice thickness 3.30 mm, interslice gap 0.4 mm, FOV = 200 mm, in-plane resolution = 3.125 mm x 3.125 mm. The data were analyzed using SPM97d. All data were realigned, co-registered to the structural MRI, and smoothed (8 mm), before an individual data analysis was performed for each subject Results In all patients the areas activated in both PET and fMR1 were strikingly similar and included both primary and secondary motor areas. This consistency of activation patterns was also preserved in the different conditions in individual patients. However, the activation patterns showed differences for each individual patient with regard to the presence or the degree of involvement of secondary motor areas e.g. the ipsi- and contralesional SMA, cingulate areas, or the and cerebellum. Differences between both methods included the higher Z-scores for fMRI (compared to the Z-scores achieved in the PET analysis) most probably due to the better signal-to-noise ratio of the fMRI data. Comments Our results demonstrate that PET and fMR1 can equally well be used for functional stroke. This methodological study of PET and fMRI activation patterns reinforces recovery following stroke. References (1) (2) (3) (4)
Weiller et al. (1993). Ann Neurol 33:181-189. Weder et al. (1994). Brain 117:593-605. Seitz et al. (1998). Arch Neurol 55:1081-1088. Cramer, SC et al. (1997). Stroke 28:2518-2527
S587
brain imaging the potential
in the subacute phase of ischemic of tMRI for studies of functional
11, Number
5, 2000, Part 2 of 2 Parts 1 D E )r;L@
METHODS
- ACQUISITION
Functional brain activation after stroke-a
PET-fMFU comparison
Gilbert Wunderlich*t, Gereon R. Fink*?, Peter H. Weiss?, Nadhu J. Shah?, Haus Hem&, Karl Zillest+, Riidiger J. Se&*, Hans-J. Freund* *Neurologische Klinik, Heinrich-Heine-Universitiit
Diisseldorf
tlnstitut fiir Medizin, Forschungszentncm Jiilich SC&O. Vogt lnstitut fiir Hirnforschung, Heinrich-Heine-Universitiit
Diisseldod
Germany
Introduction PET using “0-butanol or water is frequently used to map motor reorganization after hemiparetic stroke in the subacute and chronic phase (1,2,3). More recently, fMRI has been applied on this purpose (4), although this is criticized for a pctential influence of neurovascular decoupling following ischemic brain injury on the BOLD response depicted by EPI imaging. Using PET and fMR1. we here explore this methodological issue by comparing the pattern of activations depicted during unilateral and bilateral ipsi- and contralesional hand movements in patients with a first ischemic stroke and impaired hand function. Subjects
and Methods
Six patients (39-72 ys, five male, one female) with acute infarctions in the middle cerebral artery territory located around the central sulcus in five patients and striatocapsular in one patient were studied. PET and fMRI were carried out on the same day following oral and written informed consent. All were examined between five and 10 days after stroke and five out of six patients had made good recovery during this time with near to normal hand function. PET and fMR1 measurements were performed during rest (baseline) and three different motor tasks: (i) repetitive opening and closing of the unaffected hand, (ii) repetitive opening and closing of the affected hand, and (iii) repetitive opening and closing of the both hands in phase. PET studies were performed on a CIYSIEMENS ECAT EXACT HR camera in 3D mode with three replications per condition. For fMR1 a 1.5T Siemens Magnetom Vision was used. The fMR1 paradigm consisted of a preceding baseline of 30 s (6 x TR, not used for statistical analysis) followed by six repetitions of a cycle with 45 s activation period (9 TR) and a 45 s (9 TR) rest = baseline period (to separate the experimental conditions from one another). Sequence parameters were: Gradient-echo EPI, TE = 66 ms, TR = 5 s, flip angle = 90”, slice thickness 3.30 mm, interslice gap 0.4 mm, FOV = 200 mm, in-plane resolution = 3.125 mm x 3.125 mm. The data were analyzed using SPM97d. All data were realigned, co-registered to the structural MRI, and smoothed (8 mm), before an individual data analysis was performed for each subject Results In all patients the areas activated in both PET and fMR1 were strikingly similar and included both primary and secondary motor areas. This consistency of activation patterns was also preserved in the different conditions in individual patients. However, the activation patterns showed differences for each individual patient with regard to the presence or the degree of involvement of secondary motor areas e.g. the ipsi- and contralesional SMA, cingulate areas, or the and cerebellum. Differences between both methods included the higher Z-scores for fMRI (compared to the Z-scores achieved in the PET analysis) most probably due to the better signal-to-noise ratio of the fMRI data. Comments Our results demonstrate that PET and fMR1 can equally well be used for functional stroke. This methodological study of PET and fMRI activation patterns reinforces recovery following stroke. References (1) (2) (3) (4)
Weiller et al. (1993). Ann Neurol 33:181-189. Weder et al. (1994). Brain 117:593-605. Seitz et al. (1998). Arch Neurol 55:1081-1088. Cramer, SC et al. (1997). Stroke 28:2518-2527
S587
brain imaging the potential
in the subacute phase of ischemic of tMRI for studies of functional