Kotoo Meguro - Academia.edu (original) (raw)
Papers by Kotoo Meguro
Stroke, Oct 1, 1999
We read with great interest the recent article by Korpelainen et al. 1 Despite the fact that the ... more We read with great interest the recent article by Korpelainen et al. 1 Despite the fact that the majority of their patients reported a marked decline in all the measured sexual functioning, there was increased libido in 19 of their 192 patients. These patients did not differ from other patients as to the site of the lesion, as reported before. 2-4 However, no information was presented about intercourse frequency, deviant sexual behavior, or spousal satisfaction. We have recently seen a 69-year-old right-handed man, who presented with acute left hemiplegia. His medical history was significant for coronary artery disease diagnosed 6 years before this admission. He had stopped smoking and drinking alcohol since that time. His examination showed dense left hemiplegia, and CT showed massive infarction involving the entire right middle cerebral artery territory. Three months after the ictus, he was walking with a cane; his arm, however, showed no improvement. His wife complained that he became hypersexual and wanted to have sexual intercourse daily. She denied any deviated sexual behavior; socially, his behavior was appropriate. She stated that before ictus they had intercourse every 2 weeks and she is now unsatisfied with her husband's behavior. The patient at that time was not on any drugs reported to increase sexuality. 5 Seven months later, the patient developed poststroke seizures, and 3 years later he died of acute myocardial infarction. This case is different from the other reported cases in that the hypersexuality developed before the seizures, and the involvement of the frontal, temporal, and basal ganglia regions occurred at the same time. As Korpelainen et al 1 stated, sexual counseling after stroke is needed for the patients and their spouses. Direct questioning is usually needed, as most of the patients will not disclose their sexual problems spontaneously.
Neurosurgical Focus, Dec 1, 2004
Neurosurgery, May 1, 1985
The authors present a case of traumatic aneurysm of the posterior inferior cerebellar artery prod... more The authors present a case of traumatic aneurysm of the posterior inferior cerebellar artery produced by fracture of the clivus. Varieties of clival fractures reported in the literature are reviewed. Associated basilar or carotid arterial lesions have been reported, but traumatic aneurysm, so far as we are aware, has not. The authors emphasize the importance of a high index of suspicion of undetected traumatic intracranial aneurysm when an unusual amount of subarachnoid hemorrhage is noted on the initial computed tomographic scan, particularly if associated with displaced basal skull fracture.
Neurosurgery, Apr 1, 1990
Canadian Journal of Neurological Sciences, Jun 1, 2016
Suppl. 2-S51 fenestration of the anterior dura to permit communication of CSF between the dural s... more Suppl. 2-S51 fenestration of the anterior dura to permit communication of CSF between the dural space and pseudomeningocele. His strength and dexterity improved dramatically post-operatively. Conclusions: Spinal pseudomeningoceles following a traumatic brachial avulsion injury are typically found outside the spinal canal and are usually not associated with any neurological symptoms. There are few reported cases of post-avulsion intracanalicular pseudomeningoceles which present with delayed spinal cord compression and neurological dysfunction. Therefore, patients with a history of a traumatic avulsion injury and delayed neurological symptoms should warrant additional investigations.
Surgery for Cerebral Stroke, 1991
Childs Nervous System, Mar 14, 1997
Neurosurgery, May 1, 1990
A 22-year-old man developed fat embolism syndrome. Although a computed tomographic (CT) scan of t... more A 22-year-old man developed fat embolism syndrome. Although a computed tomographic (CT) scan of the brain showed nothing abnormal, a magnetic resonance imaging scan detected scattered spotty areas of low intensity on T1-weighted images and of high intensity on T2-weighted images. Magnetic resonance imaging is thought to be more sensitive than computed tomography in detecting cerebral fat embolism syndrome and correlates well with the clinical course.
Neurosurgery, Dec 1, 1999
The outcomes for patients with cerebellar hemorrhage are thought to be influenced by anatomic dam... more The outcomes for patients with cerebellar hemorrhage are thought to be influenced by anatomic damage to the brainstem. In this study, we investigated the magnetic resonance imaging findings in the brainstem, to examine the relationship between the degree of brainstem damage and the outcomes for patients with spontaneous cerebellar hemorrhage who are in poor-grade condition. The results for 31 patients with spontaneous cerebellar hemorrhage, with Glasgow Coma Scale scores of 8 or less at admission, who underwent magnetic resonance imaging examinations were reviewed. All patients underwent surgical intervention. The patients were divided into two groups according to their Glasgow Outcome Scale scores at the time of discharge, i.e., patients who experienced good recoveries or exhibited moderate disabilities (Group I, n = 8) and patients who exhibited severe disabilities, were in a persistent vegetative state, or had died (Group II, n = 23). We investigated obliteration of the fourth ventricle and the perimesencephalic cistern and the presence of hydrocephalus in initial computed tomographic scans and the presence of areas of high signal intensity in the brainstem in T2-weighted images. Eight patients experienced good outcomes, and 23 patients experienced poor outcomes. The overall mortality rate was 32.3%. There were no significant differences between groups with respect to computed tomographic findings such as hematoma size, but the incidence of high signal intensities in the pons and midbrain in T2-weighted images for Group II was significantly higher than that for Group I (P < 0.01). Magnetic resonance imaging clearly demonstrated brainstem damage, and high signal intensity in the brainstem was a significant prognostic factor for determining outcomes for patients with spontaneous cerebellar hemorrhage who were in poor-grade condition.
Journal of Neurosurgery, Apr 1, 1992
Neurologia Medico-chirurgica, 1999
Image-guided procedures, such as computed tomography (CT)-guided stereotactic and ultrasound guid... more Image-guided procedures, such as computed tomography (CT)-guided stereotactic and ultrasound guided methods, can assist neurosurgeons in localizing the relevant pathology. The characteristics of image-guided procedures are important for their appropriate use, especially in brain biopsy. This study reviewed the results of various image-guided brain biopsies to ascertain the advantages and disad vantages. Brain biopsies assisted by CT-guided stereotactic, ultrasound-guided , Neuronavigator-guid ed, and the combination of ultrasound and Neuronavigator-guided procedures were carried out in seven, eight, one, and three patients, respectively. Four patients underwent open biopsy without a guiding system. Twenty of 23 patients had a satisfactory diagnosis after the initial biopsy. Three patients failed to have a definitive diagnosis after the initial procedure, one due to insufficient volume sampling after CT-guided procedure, and two due to localization failure by ultrasound because the le sions were nonechogenic. All patients who underwent biopsy using the combination of ultrasound and Neuronavigator-guided methods had a satisfactory result. The CT-guided procedure provided an ef ficient method of approaching any intracranial target and was appropriate for the diagnosis of hypodense lesions, but tissue sampling was sometimes not sufficient to achieve a satisfactory diagno sis. The ultrasound-guided procedure was suitable for the investigation of hyperdense lesions, but was difficult to localize nonechogenic lesions. The combination of ultrasound and Neuronavigator methods improved the diagnostic accuracy even in nonechogenic lesions such as malignant lymphoma. There fore, it is essential to choose the most appropriate guiding method for brain biopsy according to the radiological nature of the lesions.
Neurologia Medico-chirurgica, 2002
Intraoperative angiography evaluation of the clippings of cerebral aneurysms was investigated in ... more Intraoperative angiography evaluation of the clippings of cerebral aneurysms was investigated in a series of 38 consecutive patients with unruptured cerebral aneurysms to determine any favorable impact on the outcome. Unexpected findings including major arterial occlusion or residual aneurysm were identified. Specific variables such as the size and site of aneurysm were analyzed to determine the impact on clinical outcome and the incidence of clip modification. There were 11 large and 27 small aneurysms in this series. Mortality and permanent morbidity after microsurgical clipping were 0.0% and 2.6%, respectively. Unexpected angiographic findings necessitating clip repositioning consisted of residual aneurysm in two cases and distal branch occlusion or parent vessel stenosis in four. The need for clip modification was significantly higher for large than for small aneurysms (p ＝ 0.007), and the rate of clip adjustment increased with increasing aneurysm size (p ＝ 0.008). Intraoperative assessment prior to wound closure allows for the recognition and correction of defects and decreases the risk of postoperative complications. Intraoperative angiography may become important in the microsurgical clipping of unruptured cerebral aneurysms, especially large aneurysms.
Journal of neurosurgery, Jul 1, 1999
PubMed, 1999
A 65-year-old female was admitted to our hospital with a 6-month history of a gradually enlarging... more A 65-year-old female was admitted to our hospital with a 6-month history of a gradually enlarging subcutaneous mass in the frontal region. Neurological examination on admission showed no significant abnormality. Skull X-P showed an osteolytic lesion of the frontal bone. External carotid angiogram demonstrated a tumor stain fed by the middle meningeal artery. Computed tomography (CT) showed a slightly high density mass with a marked homogeneous enhancement. MRI revealed an iso-intensity mass on both T1- and T2-weighted images. Gd-DTPA-enhanced T1-weighted images showed a mass with a marked homogeneous enhancement with the "dural tail sign" in the dura adjacent to the tumor. The tumor was totally removed; this mass was diagnosed as a multiple myeloma. No tumor cells were seen in the dura adjacent to the tumor and the mechanism of dural enhancement around the tumor was not clear. However, it is possible that the "dural tail" is due to increased vascular permeability of the dural vessels. Although the "dural tail" sign has been considered as a highly specific feature of meningioma, multiple myeloma can show the same findings on MRI. Therefore, it is important to consider the possibility of multiple myeloma in the differential diagnosis of meningeal tumors.
Clinical Neurology and Neurosurgery, Sep 1, 2000
PubMed, Jul 1, 1995
We examined the incidence of point mutations in codon 12 and 61 of N-ras gene in human gliomas us... more We examined the incidence of point mutations in codon 12 and 61 of N-ras gene in human gliomas using PCR with mismatched primers. This method detects point mutations. PCR with mismatched primers induced restriction sites in normal DNA but not in mutational DNA. Genomic DNAs were extracted from paraffin-embedded tissues and were amplified with nested PCR. Among 17 cases, point mutation has not been able to be found so far, when examined in codon 12 of N-ras gene and among 10 cases in codon 61 of N-ras gene. It can thus be said that point mutational activation of N-ras oncogene is an uncommon event in human gliomas.
Neurologia Medico-chirurgica, 1996
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques, 1984
ABSTRACTFifty-nine patients were treated in a prospective, randomized comparison of pentobarbital... more ABSTRACTFifty-nine patients were treated in a prospective, randomized comparison of pentobarbital and mannitol for the control of intracranial hypertension resulting from head injury. Patients with elevated intracranial pressure (ICP) after evacuation of intracranial hematomas were randomized to one of two treatment groups; mannitol initially or pentobarbital initially, followed by the second drug as required by further elevation of ICP. Similarly, patients with raised ICP but without hematomas requiring evacuation were randomly assigned to two treatment groups in an identical paradigm.Those with ICP elevation and no hematoma treated with pentobarbital as initial therapy had a 77% mortality compared to a 41% mortality for those with mannitol as initial treatment. Patients with evacuated hematomas had mortalities of 40% and 43% (no significant difference) for pentobarbital and mannitol respectively. In both no-hematoma and hematoma streams pentobarbital was less effective than mannit...
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques, 2016
Background:Infection to the facet joints has been reported sporadically but the significance of t... more Background:Infection to the facet joints has been reported sporadically but the significance of this type of infection has not been clarified. In our study on spine infection, we identified the cases of spinal epidural abscess with septic joints and was able to compare to cases of epidural abscess with discitis and osteomyelitis.Methods:Between 2007 and 2014, we experienced 176 cases of spine infection including discitis, osteomyelitis and epidural abscess. Retrospective review of the clinical data and radiological findings was performed. Among 176 cases, 80 patients had epidural abscess. They were divided to two groups, one with septic joint and the other with discitis and osteomyelitis.Results:23 patients were found to have septic joints with epidural abscess based on the MRI findings. Mean age was 45.5. 15 of 23 patients (65%) required surgery and all treated with laminectomy. 78% had a good neurological outcome.57 patients had epidural abscess with discitis and osteomyelitis. Me...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2005
Background: Catheterization of small-caliber blood vessels in the central nervous system can be e... more Background: Catheterization of small-caliber blood vessels in the central nervous system can be extremely challenging. Alternatively, intravenous (i.v.) administration of contrast agent is minimally invasive and therefore carries a much lower risk for the patient. With conventional X-ray equipment, volumes of contrast agent that could be safely administered to the patient do not allow acquisition of high-quality images after i.v.
Stroke, Oct 1, 1999
We read with great interest the recent article by Korpelainen et al. 1 Despite the fact that the ... more We read with great interest the recent article by Korpelainen et al. 1 Despite the fact that the majority of their patients reported a marked decline in all the measured sexual functioning, there was increased libido in 19 of their 192 patients. These patients did not differ from other patients as to the site of the lesion, as reported before. 2-4 However, no information was presented about intercourse frequency, deviant sexual behavior, or spousal satisfaction. We have recently seen a 69-year-old right-handed man, who presented with acute left hemiplegia. His medical history was significant for coronary artery disease diagnosed 6 years before this admission. He had stopped smoking and drinking alcohol since that time. His examination showed dense left hemiplegia, and CT showed massive infarction involving the entire right middle cerebral artery territory. Three months after the ictus, he was walking with a cane; his arm, however, showed no improvement. His wife complained that he became hypersexual and wanted to have sexual intercourse daily. She denied any deviated sexual behavior; socially, his behavior was appropriate. She stated that before ictus they had intercourse every 2 weeks and she is now unsatisfied with her husband's behavior. The patient at that time was not on any drugs reported to increase sexuality. 5 Seven months later, the patient developed poststroke seizures, and 3 years later he died of acute myocardial infarction. This case is different from the other reported cases in that the hypersexuality developed before the seizures, and the involvement of the frontal, temporal, and basal ganglia regions occurred at the same time. As Korpelainen et al 1 stated, sexual counseling after stroke is needed for the patients and their spouses. Direct questioning is usually needed, as most of the patients will not disclose their sexual problems spontaneously.
Neurosurgical Focus, Dec 1, 2004
Neurosurgery, May 1, 1985
The authors present a case of traumatic aneurysm of the posterior inferior cerebellar artery prod... more The authors present a case of traumatic aneurysm of the posterior inferior cerebellar artery produced by fracture of the clivus. Varieties of clival fractures reported in the literature are reviewed. Associated basilar or carotid arterial lesions have been reported, but traumatic aneurysm, so far as we are aware, has not. The authors emphasize the importance of a high index of suspicion of undetected traumatic intracranial aneurysm when an unusual amount of subarachnoid hemorrhage is noted on the initial computed tomographic scan, particularly if associated with displaced basal skull fracture.
Neurosurgery, Apr 1, 1990
Canadian Journal of Neurological Sciences, Jun 1, 2016
Suppl. 2-S51 fenestration of the anterior dura to permit communication of CSF between the dural s... more Suppl. 2-S51 fenestration of the anterior dura to permit communication of CSF between the dural space and pseudomeningocele. His strength and dexterity improved dramatically post-operatively. Conclusions: Spinal pseudomeningoceles following a traumatic brachial avulsion injury are typically found outside the spinal canal and are usually not associated with any neurological symptoms. There are few reported cases of post-avulsion intracanalicular pseudomeningoceles which present with delayed spinal cord compression and neurological dysfunction. Therefore, patients with a history of a traumatic avulsion injury and delayed neurological symptoms should warrant additional investigations.
Surgery for Cerebral Stroke, 1991
Childs Nervous System, Mar 14, 1997
Neurosurgery, May 1, 1990
A 22-year-old man developed fat embolism syndrome. Although a computed tomographic (CT) scan of t... more A 22-year-old man developed fat embolism syndrome. Although a computed tomographic (CT) scan of the brain showed nothing abnormal, a magnetic resonance imaging scan detected scattered spotty areas of low intensity on T1-weighted images and of high intensity on T2-weighted images. Magnetic resonance imaging is thought to be more sensitive than computed tomography in detecting cerebral fat embolism syndrome and correlates well with the clinical course.
Neurosurgery, Dec 1, 1999
The outcomes for patients with cerebellar hemorrhage are thought to be influenced by anatomic dam... more The outcomes for patients with cerebellar hemorrhage are thought to be influenced by anatomic damage to the brainstem. In this study, we investigated the magnetic resonance imaging findings in the brainstem, to examine the relationship between the degree of brainstem damage and the outcomes for patients with spontaneous cerebellar hemorrhage who are in poor-grade condition. The results for 31 patients with spontaneous cerebellar hemorrhage, with Glasgow Coma Scale scores of 8 or less at admission, who underwent magnetic resonance imaging examinations were reviewed. All patients underwent surgical intervention. The patients were divided into two groups according to their Glasgow Outcome Scale scores at the time of discharge, i.e., patients who experienced good recoveries or exhibited moderate disabilities (Group I, n = 8) and patients who exhibited severe disabilities, were in a persistent vegetative state, or had died (Group II, n = 23). We investigated obliteration of the fourth ventricle and the perimesencephalic cistern and the presence of hydrocephalus in initial computed tomographic scans and the presence of areas of high signal intensity in the brainstem in T2-weighted images. Eight patients experienced good outcomes, and 23 patients experienced poor outcomes. The overall mortality rate was 32.3%. There were no significant differences between groups with respect to computed tomographic findings such as hematoma size, but the incidence of high signal intensities in the pons and midbrain in T2-weighted images for Group II was significantly higher than that for Group I (P < 0.01). Magnetic resonance imaging clearly demonstrated brainstem damage, and high signal intensity in the brainstem was a significant prognostic factor for determining outcomes for patients with spontaneous cerebellar hemorrhage who were in poor-grade condition.
Journal of Neurosurgery, Apr 1, 1992
Neurologia Medico-chirurgica, 1999
Image-guided procedures, such as computed tomography (CT)-guided stereotactic and ultrasound guid... more Image-guided procedures, such as computed tomography (CT)-guided stereotactic and ultrasound guided methods, can assist neurosurgeons in localizing the relevant pathology. The characteristics of image-guided procedures are important for their appropriate use, especially in brain biopsy. This study reviewed the results of various image-guided brain biopsies to ascertain the advantages and disad vantages. Brain biopsies assisted by CT-guided stereotactic, ultrasound-guided , Neuronavigator-guid ed, and the combination of ultrasound and Neuronavigator-guided procedures were carried out in seven, eight, one, and three patients, respectively. Four patients underwent open biopsy without a guiding system. Twenty of 23 patients had a satisfactory diagnosis after the initial biopsy. Three patients failed to have a definitive diagnosis after the initial procedure, one due to insufficient volume sampling after CT-guided procedure, and two due to localization failure by ultrasound because the le sions were nonechogenic. All patients who underwent biopsy using the combination of ultrasound and Neuronavigator-guided methods had a satisfactory result. The CT-guided procedure provided an ef ficient method of approaching any intracranial target and was appropriate for the diagnosis of hypodense lesions, but tissue sampling was sometimes not sufficient to achieve a satisfactory diagno sis. The ultrasound-guided procedure was suitable for the investigation of hyperdense lesions, but was difficult to localize nonechogenic lesions. The combination of ultrasound and Neuronavigator methods improved the diagnostic accuracy even in nonechogenic lesions such as malignant lymphoma. There fore, it is essential to choose the most appropriate guiding method for brain biopsy according to the radiological nature of the lesions.
Neurologia Medico-chirurgica, 2002
Intraoperative angiography evaluation of the clippings of cerebral aneurysms was investigated in ... more Intraoperative angiography evaluation of the clippings of cerebral aneurysms was investigated in a series of 38 consecutive patients with unruptured cerebral aneurysms to determine any favorable impact on the outcome. Unexpected findings including major arterial occlusion or residual aneurysm were identified. Specific variables such as the size and site of aneurysm were analyzed to determine the impact on clinical outcome and the incidence of clip modification. There were 11 large and 27 small aneurysms in this series. Mortality and permanent morbidity after microsurgical clipping were 0.0% and 2.6%, respectively. Unexpected angiographic findings necessitating clip repositioning consisted of residual aneurysm in two cases and distal branch occlusion or parent vessel stenosis in four. The need for clip modification was significantly higher for large than for small aneurysms (p ＝ 0.007), and the rate of clip adjustment increased with increasing aneurysm size (p ＝ 0.008). Intraoperative assessment prior to wound closure allows for the recognition and correction of defects and decreases the risk of postoperative complications. Intraoperative angiography may become important in the microsurgical clipping of unruptured cerebral aneurysms, especially large aneurysms.
Journal of neurosurgery, Jul 1, 1999
PubMed, 1999
A 65-year-old female was admitted to our hospital with a 6-month history of a gradually enlarging... more A 65-year-old female was admitted to our hospital with a 6-month history of a gradually enlarging subcutaneous mass in the frontal region. Neurological examination on admission showed no significant abnormality. Skull X-P showed an osteolytic lesion of the frontal bone. External carotid angiogram demonstrated a tumor stain fed by the middle meningeal artery. Computed tomography (CT) showed a slightly high density mass with a marked homogeneous enhancement. MRI revealed an iso-intensity mass on both T1- and T2-weighted images. Gd-DTPA-enhanced T1-weighted images showed a mass with a marked homogeneous enhancement with the "dural tail sign" in the dura adjacent to the tumor. The tumor was totally removed; this mass was diagnosed as a multiple myeloma. No tumor cells were seen in the dura adjacent to the tumor and the mechanism of dural enhancement around the tumor was not clear. However, it is possible that the "dural tail" is due to increased vascular permeability of the dural vessels. Although the "dural tail" sign has been considered as a highly specific feature of meningioma, multiple myeloma can show the same findings on MRI. Therefore, it is important to consider the possibility of multiple myeloma in the differential diagnosis of meningeal tumors.
Clinical Neurology and Neurosurgery, Sep 1, 2000
PubMed, Jul 1, 1995
We examined the incidence of point mutations in codon 12 and 61 of N-ras gene in human gliomas us... more We examined the incidence of point mutations in codon 12 and 61 of N-ras gene in human gliomas using PCR with mismatched primers. This method detects point mutations. PCR with mismatched primers induced restriction sites in normal DNA but not in mutational DNA. Genomic DNAs were extracted from paraffin-embedded tissues and were amplified with nested PCR. Among 17 cases, point mutation has not been able to be found so far, when examined in codon 12 of N-ras gene and among 10 cases in codon 61 of N-ras gene. It can thus be said that point mutational activation of N-ras oncogene is an uncommon event in human gliomas.
Neurologia Medico-chirurgica, 1996
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques, 1984
ABSTRACTFifty-nine patients were treated in a prospective, randomized comparison of pentobarbital... more ABSTRACTFifty-nine patients were treated in a prospective, randomized comparison of pentobarbital and mannitol for the control of intracranial hypertension resulting from head injury. Patients with elevated intracranial pressure (ICP) after evacuation of intracranial hematomas were randomized to one of two treatment groups; mannitol initially or pentobarbital initially, followed by the second drug as required by further elevation of ICP. Similarly, patients with raised ICP but without hematomas requiring evacuation were randomly assigned to two treatment groups in an identical paradigm.Those with ICP elevation and no hematoma treated with pentobarbital as initial therapy had a 77% mortality compared to a 41% mortality for those with mannitol as initial treatment. Patients with evacuated hematomas had mortalities of 40% and 43% (no significant difference) for pentobarbital and mannitol respectively. In both no-hematoma and hematoma streams pentobarbital was less effective than mannit...
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques, 2016
Background:Infection to the facet joints has been reported sporadically but the significance of t... more Background:Infection to the facet joints has been reported sporadically but the significance of this type of infection has not been clarified. In our study on spine infection, we identified the cases of spinal epidural abscess with septic joints and was able to compare to cases of epidural abscess with discitis and osteomyelitis.Methods:Between 2007 and 2014, we experienced 176 cases of spine infection including discitis, osteomyelitis and epidural abscess. Retrospective review of the clinical data and radiological findings was performed. Among 176 cases, 80 patients had epidural abscess. They were divided to two groups, one with septic joint and the other with discitis and osteomyelitis.Results:23 patients were found to have septic joints with epidural abscess based on the MRI findings. Mean age was 45.5. 15 of 23 patients (65%) required surgery and all treated with laminectomy. 78% had a good neurological outcome.57 patients had epidural abscess with discitis and osteomyelitis. Me...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2005
Background: Catheterization of small-caliber blood vessels in the central nervous system can be e... more Background: Catheterization of small-caliber blood vessels in the central nervous system can be extremely challenging. Alternatively, intravenous (i.v.) administration of contrast agent is minimally invasive and therefore carries a much lower risk for the patient. With conventional X-ray equipment, volumes of contrast agent that could be safely administered to the patient do not allow acquisition of high-quality images after i.v.