Toshiyuki Murakami

Postoperative Changes in Cerebral Metabolites Associated with Cognitive Improvement and Impairment after Carotid Endarterectomy: A 3T Proton MR Spectroscopy Study

This study assessed the use of metabolites seen on MRS as markers of change in cognitive status after carotid artery surgery. MRS and neurocognitive testing were obtained before and after surgery in 100 patients. The results showed that cognition remained unchanged in 80%, improved in 10%, and was impaired in 10% of patients postoperatively and that in these last 2 groups, NAA/Cr correlated well the clinical status. Thus, NAA/Cr may serve as a marker of neurologic status after carotid artery surgery (see accompanying editorial by Lövblad and Pereira). BACKGROUND AND PURPOSE: Cognitive function can improve or decline after carotid endarterectomy. Proton MR spectroscopy can be used evaluate cerebral metabolites, such as N-acetylaspartate, choline, and creatine, in vivo. The purpose of the present study was to determine whether postoperative changes in cerebral metabolites measured by using 3T proton MR spectroscopy were associated with changes in cognitive function after CEA. MATERIALS AND METHODS: In 100 patients undergoing CEA for ipsilateral cervical internal carotid artery stenosis (≥70%), brain proton MR spectroscopy was performed before and after surgery. NAA/Cr and Cho/Cr ratios were measured in regions of interest placed in the centrum semiovale of both cerebral hemispheres. Neuropsychological testing was also performed preoperatively and 1 month postoperatively. Multivariate statistical analysis of factors related to postoperatively changed cognition was performed, and odds ratios with 95% confidence intervals were calculated. RESULTS: On the basis of the neuropsychological assessments, 10 (10%), 80 (80%), and 10 (10%) patients were defined as having postoperatively improved, unchanged, and impaired cognition, respectively. A positive and high ΔNAA/Cr ratio (postoperative value–preoperative value) in the cerebral hemisphere ipsilateral to the operative site was significantly associated with postoperatively improved cognition (95% CI, 13.3–21.3; P = .0016). Negative and high absolute values of the ΔNAA/Cr ratio (95% CI, 0.018–0.101; P = .0039) and ΔCho/Cr ratio (95% CI, 0.042–0.135; P = .0046) in the ipsilateral cerebral hemisphere were significantly associated with postoperatively impaired cognition. CONCLUSIONS: Postoperative changes in cerebral metabolites measured by using proton MR spectroscopy were associated with changes in cognitive function after CEA.

Oxygen extraction fraction measurement using quantitative susceptibility mapping: Comparison with positron emission tomography:

The purposes of this study are to establish oxygen extraction fraction (OEF) measurements using quantitative susceptibility mapping (QSM) of magnetic resonance imaging (MRI), and to compare QSM–OEF data with the gold standard 15O positron emission tomography (PET). Twenty-six patients with chronic unilateral internal carotid artery or middle cerebral artery stenosis or occlusion, and 15 normal subjects were included. MRI scans were conducted using a 3.0 Tesla scanner with a three-dimensional spoiled gradient recalled sequence. QSM images were created using the morphology-enabled dipole inversion method, and OEF maps were generated from QSM images using extraction of venous susceptibility induced by deoxygenated hemoglobin. Significant correlation of relative OEF ratio to contra-lateral hemisphere between QSM–OEF and PET–OEF was observed (r = 0.62, p < 0.001). The local (intra-section) correlation was also significant (r = 0.52, p < 0.001) in patients with increased PET–OEF. The sensitivity and specificity of OEF increase in QSM was 0.63 (5/8) and 0.89 (16/18), respectively, in comparison with PET. In conclusion, good correlation was achieved between QSM–OEF and PET–OEF in the identification of elevated OEF in affected hemispheres of patients with unilateral chronic steno-occlusive disease.

Postoperative increase in cerebral white matter fractional anisotropy on diffusion tensor magnetic resonance imaging is associated with cognitive improvement after uncomplicated carotid endarterectomy: tract-based spatial statistics analysis.

BACKGROUND Carotid endarterectomy (CEA) might improve cognitive function. Fractional anisotropy (FA) values in the cerebral white matter derived from diffusion tensor magnetic resonance imaging (DTI) correlate with cognitive function in patients with various central nervous system diseases. OBJECTIVE To use tract-based spatial statistics to determine whether postoperative changes of FA values in the cerebral white matter derived from DTI are associated with cognitive improvement after uncomplicated CEA. METHODS In 80 patients undergoing CEA for ipsilateral internal carotid artery stenosis (≥70%), FA values in the cerebral white matter were derived from DTI before and 1 month after surgery and were analyzed by using tract-based spatial statistics. Neuropsychological testing, consisting of the Wechsler Adult Intelligence Scale Revised, the Wechsler Memory Scale and the Rey-Osterreith Complex Figure test, was also performed preoperatively and after the first postoperative month. RESULTS Based on the neuropsychological assessments, 11 (14%) patients were defined as having postoperatively improved cognition. The difference between the 2 mean FA values (postoperative values minus preoperative values) in the cerebral hemisphere ipsilateral to surgery was significantly associated with postoperative cognitive improvement (95% confidence intervals, 2.632-9.877; P = .008). White matter FA values in patients with postoperative cognitive improvement were significantly increased after surgery in the whole ipsilateral cerebral hemisphere, in the contralateral anterior cerebral artery territory, and in the watershed zone between the contralateral anterior and middle cerebral arteries. CONCLUSION Postoperative increase in cerebral white matter FA on DTI is associated with cognitive improvement after uncomplicated CEA.

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.

Brain temperature measured by 1 H-magnetic resonance spectroscopy in acute and subacute carbon monoxide poisoning

IntroductionBrain temperature (BT) is associated with the balance between cerebral blood flow and metabolism according to the “heat-removal” theory. The present study investigated whether BT is abnormally altered in acute and subacute CO-poisoned patients by using 1H-magnetic resonance spectroscopy (MRS).MethodsEight adult CO-poisoned patients underwent 3-T magnetic resonance imaging in the acute and subacute phases after CO exposure. MRS was performed on deep cerebral white matter in the centrum semiovale, and MRS-based BT was estimated by the chemical shift difference between water and the N-acetyl aspartate signal. We defined the mean BT + 1.96 standard deviations of the BT in 15 healthy controls as the cutoff value for abnormal BT increases (p < 0.05) in CO-poisoned patients.ResultsBT of CO-poisoned patients in both the acute and subacute phases was significantly higher than that of the healthy control group. However, BT in the subacute phase was significantly lower than in the acute phase. On the other hand, no significant difference in body temperature was observed between acute and subacute CO-poisoned patients. BT weakly correlated with body temperature, but this correlation was not statistically significant (rho = 0.304, p = 0.2909).ConclusionsThe present results suggest that BT in CO-poisoned patients is abnormally high in the acute phase and remains abnormal in the subacute phase. BT alteration in these patients may be associated with brain perfusion and metabolism rather than other factors such as systemic inflammation and body temperature.

Early onset of PRES in a patient with a subarachnoid haemorrhage due to a ruptured intracranial aneurysm.

Abstract Posterior reversible encephalopathy syndrome (PRES) is rarely associated with subarachnoid haemorrhage (SAH). We present a case involving a patient who developed PRES, prior to induction of hypertensive therapy, 2 days after the onset of a SAH due to a ruptured intracranial aneurysm.

Chronological Changes in Brain Blood Flow and Central Benzodiazepine Receptor Binding Potential in a Patient with Symptomatic Epilepsy after Surgery for Aneurysmal Subarachnoid Hemorrhage: 123I-Iomazenil Single-Photon Emission Computed Tomography Studies

Early 123I-iomazenil single-photon emission computed tomography (SPECT) images are correlated with blood flow in the brain, and late images are correlated with cortical benzodiazepine receptor binding potential. Reduced metabolism in the contralateral cerebral hemisphere is indicated by crossed cerebellar hypoperfusion (CCH). We present the case of a 63-year-old man who developed symptomatic epilepsy 13 days after surgery for an aneurysmal subarachnoid hemorrhage. Early images on 123I-iomazenil SPECT 2 days after seizure onset revealed CCH and hyperperfusion in the affected cerebral hemisphere where benzodiazepine receptor binding potential was reduced in late images on 123I-iomazenil SPECT. These abnormal findings resolved on repeated 123I-iomazenil SPECT 1 month after seizure onset. The case we present here is consistent with the idea that the central benzodiazepine receptor system in the human brain undergoes changes that are related to seizures due to epilepsy.

Basal ganglia germinoma presenting as a growing intratumoral hematoma in a 12-year-old boy

Dear Editor: Typical radiographic findings of basal ganglia (BG) germinomas include cystic formation, brain atrophy on the ipsilateral side of the tumor, and intratumoral hemorrhages [1–3]. Approximately 50–70 % of BG germinoma involve intratumoral hemorrhages [2, 3]. A 12-year-old boy with a sudden onset of left hemiparesis visited a local hospital. Head computed tomography (CT) demonstrated a hemorrhage in the right BG. He visited our institute for further examination. On admission, he presented with slight left hemiparesis. Magnetic resonance (MR) imaging 1 month after the onset of the symptom demonstrated a mass lesion composed of hemorrhages of different phases in the right globus pallidus (Fig. 1a, b). This lesion was not accompanied by a mass effect and was slightly enhanced with contrast gadolinium (Fig. 1c). The lesion was also accompanied by shrinkage of the right cerebral peduncle and dilation of the right sylvian fissure. Blood cell count, α-fetoprotein, human chorionic gonadotropin, and carcinoembryonic antigen were within normal limits. The patient underwent rehabilitation in another clinic, and his hemiparesis gradually improved. However, 2 months after the onset of the symptom, the symptoms gradually worsened. MR imaging showed a BG lesion with an increase in the size of the hematoma compared with previous images (Fig. 1d, e). The patient underwent craniotomy under general anesthesia. MR imaging immediately before craniotomy (3 months after the onset of the symptom) revealed a further increase in the size of the hematoma in the BG lesion (Fig. 1f, g). Under a surgical microscope, the insular cortex was incised via the right sylvian fissure. The lesion was composed of a chronic hematoma surrounded by a thin layer of grayish elastic tissue. The hematoma was aspirated, and the tissue was removed. No new neurological deficits were observed after surgery. Histological examination of the surgical specimen demonstrated a pure germinoma accompanied by hemorrhages and rich blood vessels (Fig. 2). The patient underwent radiotherapy (23.4 Gy/13 fractions) and chemotherapy with carboplatin and etoposide (three cycles, every 4 weeks). The tumor resolved on MR imaging and did not recur at 8 months after surgery. On initial MR imaging of the present patient, the lesion was not accompanied by a mass effect, and the cerebral peduncle and the cerebral hemisphere ipsilateral to the lesion were atrophic. These findings suggested that this lesion had been present for a long time and chronically involved the internal capsula. Although these are typical findings of BG germinomas [1–3], other lesions such as low-grade astrocytomas may also exhibit the same findings [4]. The incidence of intratumoral hemorrhages is high in malignant brain tumors such as glioblastomas and metastatic tumors [5]. In the pathogenesis of these types of tumors, mechanical factors can cause incomplete necrosis with softening and subsequent hemorrhaging into the brain tissue. Tumor encasement of a cerebral end artery can also lead to occlusion and complete necrosis of the vessel wall with secondary hemorrhaging. Further, metabolic factors in a rapidly expanding tumor may deprive tumor tissue of adequate nutrition, causing tumoral * Yasushi Ogasawara yaushi.ogasawara.neuron@gmail.com

Microsurgical clipping for the true posterior communicating artery aneurysm in the distal portion of the posterior communicating artery

Background: Aneurysms arising from the posterior communicating artery (PCoA) itself are rare in which aneurysms usually located in the proximal portion of the PCoA. The authors report a case of the true PCoA ruptured aneurysm in the distal portion of the PCoA. Case Description: The patient was an 83-year-old man who suffered subarachnoid hemorrhage. Cerebral angiography revealed a saccular aneurysm arising on the fetal type right PCoA itself in the distal portion of the PCoA. 2 days after the onset of symptoms, the patient underwent right interfascial pterional craniotomy, with anterior temporal approach. The aneurysm was successfully clipped with the preservation of both the PCoA and the thalamoperforating artery. Conclusion: We speculated that blood flow into the PCoA gradually increased after occlusion of the left vertebral artery, which induced tortuosity of the PCoA. As a result, hemodynamic stress might increase near the curvature and cause aneurysm formation.