Kenta Aso

Postcarotid endarterectomy improvement in cognition is associated with resolution of crossed cerebellar hypoperfusion and increase in 123I-iomazenil uptake in the cerebral cortex: a SPECT study.

Background: The purpose of the present study was to investigate whether resolution of crossed cerebellar hypoperfusion (CCH) and increase in 123I-iomazenil (IMZ) uptake in the ipsilateral cerebral cortex after carotid endarterectomy (CEA) are associated with postoperative improvement of cognitive function. Methods: Neuropsychological testing was performed preoperatively and after 1 postoperative month in 79 patients undergoing CEA for ipsilateral internal carotid artery stenosis (≧70%). Brain perfusion single photon emission computed tomography (SPECT) using N-isopropyl-p-123I-iodoamphetamine and 123I-IMZ SPECT were also performed before and after surgery. Data were analyzed using a three-dimensional stereotaxic region of interest template. Results: Seven patients (9%) showed improvement in postoperative cognitive function. All the 7 patients exhibited both postoperative increase in blood flow in the ipsilateral cerebral cortex and resolution of CCH. Five patients (6%) had a postoperative hemispheric increase in 123I-IMZ uptake, and cognitive function improved in all of these 5 patients. Analysis by a receiver operating characteristic (ROC) curve was used to estimate the ability to discriminate between patients with and without postoperative cognitive improvement. The area under the ROC curve was significantly greater when analyzing the magnitude of postoperative resolution of CCH (0.991; 95% CI 0.984–1.001) or postoperative hemispheric increase in 123I-IMZ uptake (0.981; 95% CI 0.972–0.999) when compared with the magnitude of postoperative increase in cerebral blood flow (0.929; 95% CI 0.886–0.971) (p < 0.05). Conclusions: Resolution of CCH and increase in 123I-IMZ uptake in the ipsilateral cerebral cortex after CEA is associated with postoperative improvement in cognitive function. These results may indicate that cognitive impairment is related to a state of potentially reversible central benzodiazepine receptor downregulation in the cortex in response to transient ischemic attack or minor stroke.

Brain Temperature Measured Using Proton MR Spectroscopy Detects Cerebral Hemodynamic Impairment in Patients With Unilateral Chronic Major Cerebral Artery Steno-Occlusive Disease Comparison With Positron Emission Tomography

Background and Purpose— Brain temperature is determined by the balance between heat produced by cerebral energy turnover and heat removed by cerebral blood flow. The purpose of the present study was to investigate whether brain temperature measured noninvasively using proton MR spectroscopy can detect cerebral hemodynamic impairment in patients with unilateral chronic internal carotid or middle cerebral artery occlusive disease when compared with positron emission tomography. Methods— Brain temperature, cerebral blood flow, and metabolism were measured using proton MR spectroscopy and 15O-positron emission tomography, respectively, in 21 normal subjects and 37 patients. Positron emission tomography images were coregistered with MR images and resliced automatically using image analysis software. Regions of interest placed in both cerebral hemispheres on MR images were automatically superimposed in these resliced positron emission tomography images. Results— A significant correlation was observed between brain temperature difference (affected hemisphere–contralateral hemisphere) and both cerebral blood volume and oxygen extraction fraction ratio (affected hemisphere/contralateral hemisphere; r=0.607; P=0.0004 and r=0.631; P=0.0002). With abnormally elevated cerebral blood volume or oxygen extraction fraction ratio defined as higher than the mean +2 SDs obtained from normal subjects, brain temperature difference provided 86% or 92% sensitivity and 87% or 84% specificity with 80% or 73% positive and 91% or 95% negative predictive values for detecting abnormally elevated cerebral blood volume or oxygen extraction fraction ratios, respectively. Conclusions— Brain temperature measured using proton MR spectroscopy can detect cerebral hemodynamic impairment in patients with unilateral chronic major cerebral artery steno-occlusive disease.

Central benzodiazepine receptor binding potential and CBF images on SPECT correlate with oxygen extraction fraction images on PET in the cerebral cortex with unilateral major cerebral artery occlusive disease.

Oxygen extraction fraction (OEF) is a key predictor of stroke recurrence in patients with symptomatic major cerebral arterial occlusive disease. The purpose of the present study was to compare central benzodiazepine receptor binding potential (BRBP) and cerebral blood flow (CBF) images on SPECT with OEF images on PET in patients with chronic unilateral middle cerebral artery (MCA) or internal carotid artery (ICA) occlusive disease. Methods: OEF, CBF, and BRBP were assessed using 15O PET and N-isopropyl-p-123I-iodoamphetamine and 123I-iomazenil SPECT, respectively, in 20 healthy subjects and in 34 patients with unilateral MCA or ICA occlusive disease. All images were transformed into the standard brain size and shape by linear and nonlinear transformation using statistical parametric mapping for anatomic standardization. A region of interest (ROI) was automatically placed according to the arterial supply using a 3-dimensional stereotactic ROI template, and the ratio of the value in the affected side to that in the contralateral side was calculated in each image. Results: Among patients with occlusive disease, a significant positive correlation was observed between PET OEF and SPECT BRBP/CBF ratios in 3 cerebral cortical regions (r = 0.851, P < 0.0001, for anterior cerebral artery [ACA] ROI; r = 0.807, P < 0.0001, for MCA ROI; and r = 0.774, P < 0.0001, for posterior cerebral artery [PCA] ROI), but there were no correlations between these 2 parameters in the basal ganglia or the cerebellum. When an abnormally elevated PET OEF ratio was defined as a value greater than the mean + 2 SDs obtained in healthy subjects, sensitivity and specificity were, respectively, 100% and 96% for the ACA ROI, 100% and 89% for the MCA ROI, and 100% and 93% for the PCA ROI for the SPECT BRBP/CBF ratio for detecting an abnormally elevated PET OEF ratio. Conclusion: BRBP/CBF images on SPECT correlate with OEF images on PET in a specific clinical setting—that is, in the cerebral cortex of patients with chronic unilateral MCA or ICA occlusive disease.

Brain Temperature Measured by Using Proton MR Spectroscopy Predicts Cerebral Hyperperfusion after Carotid Endarterectomy

PURPOSE To determine whether brain temperature measured by using preoperative proton magnetic resonance (MR) spectroscopy could help identify patients at risk for cerebral hyperperfusion after carotid endarterectomy (CEA). MATERIALS AND METHODS Institutional review board approval and informed consent were obtained. Acquisition of proton MR spectroscopic data by using point-resolved spectroscopy without water suppression was performed before CEA in the bilateral cerebral hemispheres of 84 patients with unilateral internal carotid artery stenosis (> or =70%) and without contralateral internal carotid artery steno-occlusive disease. Brain temperature was calculated from the chemical shift difference between water and N-acetylaspartate signals at proton MR spectroscopy. Cerebral blood flow (CBF) was also measured by using single photon emission computed tomography and N-isopropyl-p-[(123)I]-iodoamphetamine before and immediately after CEA and on the 3rd postoperative day. The relationship between each variable and the development of post-CEA hyperperfusion (CBF increase > or = 100% compared with preoperative values) was evaluated with univariate statistical analysis followed by multivariate analysis. RESULTS A linear correlation was observed between preoperative brain temperature difference (the value in the affected hemisphere minus the value in the contralateral hemisphere) and increases in CBF immediately after CEA (r = 0.763 and P < .001) when the preoperative brain temperature difference was greater than 0. Cerebral hyperperfusion immediately after CEA was observed in nine patients (11%). Elevated preoperative brain temperature difference was the only significant independent predictor of post-CEA hyperperfusion. When elevated brain temperature difference was defined as a marker of hemodynamic impairment in the affected cerebral hemisphere, use of preoperative brain temperature difference resulted in 100% sensitivity and 87% specificity, with a 47% positive predictive value and a 100% negative predictive value for the prediction of post-CEA hyperperfusion. Hyperperfusion syndrome developed on the 3rd and 4th postoperative days in two of the nine patients who exhibited hyperperfusion immediately after CEA. CONCLUSION Brain temperature measured by using preoperative proton MR spectroscopy may help identify patients at risk for post-CEA cerebral hyperperfusion.

Accuracy of central benzodiazepine receptor binding potential/cerebral blood flow SPECT imaging for detecting misery perfusion in patients with unilateral major cerebral artery occlusive diseases: comparison with cerebrovascular reactivity to acetazolamide and cerebral blood flow SPECT imaging.

Purpose: The aim of the present study was to determine whether central benzodiazepine receptor binding potential (BRBP)/cerebral blood flow (CBF) or a combination of CBF and cerebrovascular reactivity (CVR) to acetazolamide on single-photon emission computed tomography (SPECT) more accurately detects misery perfusion, indicating elevation of absolute value of oxygen extraction fraction (OEF) on positron emission tomography (PET), in patients with unilateral major cerebral artery occlusive diseases. Methods: In 84 patients, OEF, CBF, CVR to acetazolamide, and BRBP were assessed using 15O-PET and N-isopropyl-p-[123I]-iodoamphetamine and [123I]-iomazenil SPECT, respectively. A region of interest was automatically placed in the middle cerebral artery territory using a 3-dimensional stereotactic region of interest template. Results: Sensitivity, specificity, and positive and negative predictive values for the affected side-to-contralateral side asymmetry on SPECT-BRBP/CBF to detect the abnormally elevated PET-OEF in the affected hemisphere were 100%, 86.4%, 66.7%, and 100%, respectively. Area under the receiver operating characteristic curve in detecting the abnormally elevated PET-OEF in the affected hemisphere did not differ between analysis of the combination of SPECT-CBF and SPECT-CVR in the affected hemisphere (0.89; 95% confidence interval, 0.80–0.94) and that of the affected side-to-contralateral side asymmetry on SPECT-BRBP/CBF (0.93; 95% confidence interval, 0.86–0.97). The combination of the 3 detected abnormally elevated PET-OEF with 97.0% specificity and 90.0% positive predictive value. Conclusions: The accuracy of central BRBP/CBF asymmetry on SPECT is equivalent to that of the combination of CBF and CVR to acetazolamide on SPECT for detecting misery perfusion in patients with unilateral major cerebral artery occlusive disease.

Preoperative Central Benzodiazepine Receptor Binding Potential and Cerebral Blood Flow Images on SPECT Predict Development of New Cerebral Ischemic Events and Cerebral Hyperperfusion After Carotid Endarterectomy

Risk factors for cerebrovascular complications developing during or after carotid endarterectomy (CEA) include preoperative impairments in cerebral hemodynamics, as detected by the demonstration of decreased cerebrovascular reactivity (CVR) to acetazolamide on brain perfusion SPECT. Central benzodiazepine receptor binding potential (CBRBP) and cerebral blood flow (CBF) images on SPECT provide high sensitivity and high specificity for detecting misery perfusion in patients with chronic unilateral major cerebral artery occlusive disease. The aim of the present study was to determine whether preoperative CBRBP/CBF images on SPECT could identify patients at risk for new cerebral ischemic events, including neurologic deficits and cerebral ischemic lesions on diffusion-weighted MRI, or cerebral hyperperfusion after CEA and to compare the predictive accuracy of CBRBP/CBF with that of CVR to acetazolamide on SPECT. Methods: CBF, CVR, and CBRBP were assessed using N-isopropyl-p-123I-iodoamphetamine (123I-IMP) and 123I-iomazenil SPECT before CEA in 112 patients with unilateral internal carotid artery stenosis (≥70%). CBF measurement using 123I-IMP SPECT was also performed immediately and 3 d after CEA. A region of interest was automatically placed in the middle cerebral artery territory in both cerebral hemispheres using a 3-dimensional stereotactic region-of-interest template. Diffusion-weighted MRI was performed within 3 d before and 24 h after surgery. Results: A preoperative increase in the affected side–to–contralateral side asymmetry on CBRBP/CBF value was the only significant independent predictor of postoperative new cerebral ischemic events (95% confidence intervals [CI], 1.145–1.608; P = 0.0004) or post-CEA hyperperfusion (95% CI, 1.244–2.252; P = 0.0007). There was no difference in the ability to predict post-CEA hyperperfusion when comparing the area under the receiver-operating-characteristic curve of the affected side–to–contralateral side asymmetry on CBRBP/CBF and that of the CVR in the affected hemisphere. However, the former value (0.924; 95% CI, 0.854–0.972) was significantly greater than the latter value (0.782; 95% CI, 0.697–0.852) for the prediction of new postoperative cerebral ischemic events (P < 0.05). Conclusion: Preoperative CBRBP/CBF images on SPECT can more accurately identify patients at risk for cerebrovascular complications occurring during or after CEA when compared with preoperative CVR to acetazolamide.

Comparison of early and late images on 123I-iomazenil SPECT with cerebral blood flow and oxygen extraction fraction images on PET in the cerebral cortex of patients with chronic unilateral major cerebral artery occlusive disease.

ObjectiveThe aim of the present study was to determine whether early and late/early images on 123I-iomazenil (IMZ) single-photon emission computed tomography (SPECT) correlate with cerebral blood flow (CBF) images and oxygen extraction fraction (OEF) images on PET, respectively, in the cerebral cortex of patients with chronic unilateral middle cerebral artery or internal carotid artery occlusive disease. MethodsIn 20 normal individuals and in 68 patients, CBF and OEF were assessed using 15O-PET, and brain SPECT scans were initiated immediately after (early images) and 180 min after (late images) the administration of 123I-IMZ. A region of interest was automatically placed in the middle cerebral artery territory in both cerebral hemispheres using a three-dimensional stereotaxic region of interest template, and the ratio of the value in the affected side to that in the contralateral side was calculated in each image. ResultsAmong patients, a significant positive correlation was observed between PET-CBF ratios and the SPECT-early IMZ ratios (r=0.797, P<0.0001) as well as between the PET-OEF ratios and the SPECT-late/early IMZ ratios (r=0.679, P<0.0001). When an abnormally elevated PET-OEF ratio was defined as a value greater than the mean+2 SD obtained in normal participants, the SPECT-late/early IMZ ratios yielded 100% sensitivity and 93% specificity, with 76% positive-predictive and 100% negative-predictive values for detecting abnormally elevated PET-OEF ratios. ConclusionEarly and late/early images on 123I-IMZ SPECT correlate with CBF images and OEF images on PET, respectively, in the cerebral cortex of patients with chronic unilateral major cerebral artery occlusive disease.

Spontaneous recovery of reduced cortical central benzodiazepine receptor binding potential on I-123 Iomazenil SPECT in a patient with status epilepticus.

Abstract: A reduction in cortical benzodiazepine receptor binding potential on late images of I-123 iomazenil SPECT indicates irreversible neural damage or loss. We present the case of a 26-year-old woman with status epilepticus in whom SPECT imaging using I-123 iomazenil and I-123 N-isopropyl-p-iodoamphetamine 7 and 9 days after the last seizure, respectively, demonstrated reduction in central benzodiazepine receptor binding potential with hyperperfusion in the affected cerebral hemisphere and crossed cerebellar hypoperfusion. However, 3 months later, repeat studies showed resolution of the reduction in cortical benzodiazepine receptor binding potential, resolution of hyperperfusion, and resolution of crossed cerebellar hypoperfusion.

Arterial bypass surgery using a spontaneously formed "bonnet" superficial temporal artery in a patient with symptomatic common carotid artery occlusion: case report.

BACKGROUND Common carotid artery (CCA) occlusive disease may cause hemodynamic cerebral ischemia resulting in the development of ischemic symptoms. The blood flow in the superficial temporal artery (STA) ipsilateral to the occluded CCA is usually poor, which limits its use as a donor artery for extracranial-intracranial arterial bypass surgery. CLINICAL PRESENTATION Despite antiplatelet therapy, recurrent transient ischemic attacks manifesting as motor aphasia developed in a 72-year-old man. Neuroradiological imaging revealed misery perfusion in the bilateral cerebral hemispheres caused by left CCA occlusion and right internal carotid artery occlusion. Blood flow from the STA contralateral to the occluded CCA perfused the ipsilateral STA over the midline in a retrograde fashion. INTERVENTION After confirming the direction and the pressure of the blood flow in the spontaneously formed “bonnet” STA, the STA was anastomosed to a cortical artery in the symptomatic frontal lobe so that blood flow in the ipsilateral STA was supplied from the contralateral STA. The procedure was accomplished without difficulty, and no further ischemic symptoms developed after surgery. Postoperative cerebral angiography demonstrated an increase in collateral flow to the anastomosed bonnet STA and perfusion to an entire territory of the upper trunk of the symptomatic middle cerebral artery via the anastomosis. CONCLUSION This case suggests that arterial bypass surgery can be performed using a spontaneously formed bonnet STA as a donor in a patient with symptomatic CCA occlusion.

Straight Fenestrated Clips in Surgical Management of Internal Carotid Artery Aneurysms: Technical Note

BACKGROUND Using angled fenestrated clips for posteromedially projecting internal carotid artery (ICA) aneurysms may allow the surgeon to simultaneously obliterate the aneurysmal neck and preserve the branching artery by applying the blade of the clip parallel to the ICA. However, using these clips when the aneurysm neck involves the branching artery may have a risk of branching artery stenosis, occlusion, or incomplete obliteration of the aneurysm. CASE DESCRIPTION A 52-year-old woman developed a subarachnoid hemorrhage. Three-dimensional computed tomography angiography showed a saccular aneurysm arising from the left ICA-posterior communicating artery (PCoA) bifurcation. The aneurysmal fundus projected posteromedially, and the PCoA was larger than the ipsilateral P1 segment, in which its origin involved the aneurysmal neck. Tandem straight fenestrated clips were applied across the ICA, followed by reconstruction of the ICA wall with preservation of the PCoA and obliteration of the aneurysm. CONCLUSION When using angled fenestrated clips is unsuitable because of a risk of branching artery stenosis, occlusion, or incomplete obliteration of the aneurysm, using multiple straight fenestrated clips may be a useful alternative.