Recent and future evolutions in neuroSPECT apply to radiopharmaceuticals techniques and the syner... more Recent and future evolutions in neuroSPECT apply to radiopharmaceuticals techniques and the synergistic use of different imaging modalities in the work-up of neurological disorders. The introduction of Technetium labelled perfusion tracers, which could pass the intact blood-brain barrier, together with the implementation of the tomographic principle, by making the conventional gamma camera rotating, enabled estimation of regional cerebral blood flow and indirectly of local brain metabolism. In addition at present Thallium-201 and Tc-99m sestaMIBI allow functional detection of viable tumor tissue, without interference from previous surgery or radiotherapy as seen using CT-scan or MRI. In neurology this has led to the recognition of SPECT by the American Academy of Neurology (Therapeutics and technology subcommittee) as an established or promising tool in major neurological disorders such as dementia, stroke and epilepsy, while other domains such as brain oncology are considered inves...
PURPOSE/AIM Dynamic arterial spin labeling (dASL) is a non-invasive MR perfusion method able to d... more PURPOSE/AIM Dynamic arterial spin labeling (dASL) is a non-invasive MR perfusion method able to depict global and local states of hypo- and hyperperfusion qualitatively and quantitatively. We illustrate its use in common disease entities with emphasis on cerebrovascular disease and neuro-oncology. Correlation is made with structural MRI, DSC-PWI, MRS and PET. CONTENT ORGANIZATION Concerning cerebrovascular disease, we show cases of ischemia, chronic cerebrovascular occlusive disease, PRES, vasculitis and Moya Moya, as well as the possibility of testing vascular reactivity. Moreover, using a dynamic ASL sequence with 10 time steps, the sequential time evolution in arteriovenous malformations is depicted. In the setting of multimodal tumor imaging, we focus on tumor grading, as well as on treatment follow-up: tumor progression, tumor recurrence and radiation necrosis. SUMMARY Dynamic arterial spin labeling (dASL) is a non-invasive MR perfusion method capable of demonstrating perfusion...
Alzheimer disease (AD), a progressive neurodegenerative disorder, is the most common cause of dem... more Alzheimer disease (AD), a progressive neurodegenerative disorder, is the most common cause of dementia in the elderly. Current consensus statements have emphasized the need for early recognition of AD. In vivo magnetic resonance spectroscopy (MRS) has recently opened new possibilities for noninvasively assessing metabolic and functional correlates of dementia in research and clinical settings. The purpose of this article is to provide a conceptual review, covering the principles of MRS and main pathological findings related to AD. H1 MRS has the possibility of being a neuroimaging marker because the potential clinical applications in patients with AD include a role in early diagnosis and differential diagnosis of AD, a role in prognosis of disease severity, a role in predicting future progression to AD in patients with mild cognitive impairment and tracking disease progression. MRS can also help in the evaluation of treatment effects and in the development of new therapies. In concl...
To find an optimal diagnostic protocol for the presurgical MR evaluation of patients with tempora... more To find an optimal diagnostic protocol for the presurgical MR evaluation of patients with temporal lobe epilepsy. MR imaging in 14 healthy subjects and 25 consecutive patients with temporal lobe epilepsy was performed in paracoronal sections perpendicular to the hippocampi with T1-weighted inversion recovery and T2 weighting. Volume measurements of the hippocampus/amygdala complex were performed and a multiecho sequence yielded T2-calculated images. Hippocampal disease was seen in 22 of 25 temporal lobe epilepsy patients on paracoronal T1-weighted inversion recovery images. Four had bilateral abnormalities. Characteristic for hippocampal disease were features such as volume loss, decreased signal, and loss of internal morphology. Only 17 of 25 patients demonstrated hippocampal pathology on T2-weighted images, and in one patient this was bilateral. Patients with only minimal structural loss on T1-weighted inversion recovery had normal T2-weighted images. T2 calculation was no more se...
All muscles of the neck have a role in motion and postural control of the cervical region. The ai... more All muscles of the neck have a role in motion and postural control of the cervical region. The aim of this study was to investigate the difference in muscle/fat index between (1) cervical flexors and extensors and (2) deep and superficial neck muscles. Twenty-six healthy subjects participated in the study. Magnetic resonance imaging (MRI) was used to quantify muscle fat indices in different cervical flexor and extensor muscles at the C4-C5 level. Overall, the ventral muscles had a significantly lower fat content compared with the dorsal muscles (P < or = 0.001). For the cervical extensors, significant differences between the muscle/fat index of the deep and superficial muscles were found (P < or = 0.001). For the cervical flexors, there were no significant differences between the different muscles. The higher fat content in the dorsal muscles can be explained by a discrepancy in function between the spine extensors and flexors, reflected in a different muscle fiber distributio...
Beta-alanine (BA) supplementation has been shown to augment muscle carnosine concentration, there... more Beta-alanine (BA) supplementation has been shown to augment muscle carnosine concentration, thereby promoting high-intensity (HI) exercise performance. Trained muscles of athletes have a higher increase in carnosine concentration after BA supplementation compared to untrained muscles, but it remains to be determined whether this is due to an accumulation of acute exercise effects or to chronic adaptations from prior training. The aim of the present study was to investigate whether high-volume (HV) and/or HI exercise can improve BA-induced carnosine loading in untrained subjects. All participants (n = 28) were supplemented with 6.4 g/day of BA for 23 days. The subjects were allocated to a control group, HV, or HI training group. During the BA supplementation period, the training groups performed nine exercise sessions, consisting of either 75-90 min continuous cycling at 35-45% Wmax (HV) or 3 to 5 repeats of 30 s cycling at 165% Wmax with 4 min recovery (HI). Carnosine content was measured in soleus and gastrocnemius medialis by proton magnetic resonance spectroscopy. There was no difference in absolute increase in carnosine content between the groups in soleus and gastrocnemius muscle. For the average muscle carnosine content, a higher absolute increase was found in HV (+2.95 mM; P = 0.046) and HI (+3.26 mM; P = 0.028) group compared to the control group (+1.91 mM). However, there was no additional difference between the HV and HI training group. HV and HI exercise training showed no significant difference on BA-induced muscle carnosine loading in soleus and gastrocnemius muscle. It can be suggested that there can be a small cumulative effect of exercise on BA supplementation efficiency, although differences did not reach significance on individual muscle level.
To compare the organ doses and lifetime-attributable risk of cancer for electrocardiogram-trigger... more To compare the organ doses and lifetime-attributable risk of cancer for electrocardiogram-triggered sequential and high-pitch helical scanning in a clinical patient population. Phantom thermoluminiscence dosimeter measurements were used as a model for the organ dose assessment of 314 individual patients who underwent coronary computed tomographic angiography. Patient-specific lifetime-attributable cancer risks were calculated. Phantom measurements showed that heart rate had a significant influence on the delivered radiation exposure in sequential mode, and calcium scoring and contrast bolus tracking scans make a nonnegligible contribution to patients&amp;amp;amp;amp;#39; dose. Therefore, they should be taken into account for patients&amp;amp;amp;amp;#39; organ dose estimations. Median cancer induction risks are low, with 0.008% (0.0016%) and 0.022% (0.056%) for high-pitch and sequential scanning for men (women), respectively. The use of high-pitch helical scanning leads to 65% and 72% lower lifetime-attributable risk values for men and women, respectively, compared with sequential scanning.
To study the value of different parameters derived from single-voxel proton MR spectroscopy of th... more To study the value of different parameters derived from single-voxel proton MR spectroscopy of the mesial temporal lobes in the lateralization of the epileptogenic zone in patients with temporal lobe epilepsy. We studied 12 healthy volunteers and 21 patients with temporal lobe epilepsy refractory to medical treatment, which was clearly lateralized with electroencephalography (EEG) and MR imaging. The mesial temporal lobes were investigated with single-voxel proton MR spectroscopy using a point-resolved spectroscopic sequence with an echo time of 135 milliseconds. The normalized concentration of N-acetylaspartate (NAA), creatine (Cr), and choline-containing compounds (Cho), and the metabolite ratios NAA/Cho+Cr, NAA/Cr, Cho/Cr, and NAA/Cho were calculated from the spectra. Using these values and an asymmetry index, we assigned the patients to one of five lateralization categories. The most consistent MR spectroscopic parameter for clear lateralization was the NAA/Cho+Cr ratio, followe...
Proton magnetic resonance spectroscopy ((1)H-MRS) has been used in a number of studies to assess ... more Proton magnetic resonance spectroscopy ((1)H-MRS) has been used in a number of studies to assess noninvasively the temporal changes of lactate (Lac) in the activated human brain. Migraine neurobiology involves lack of cortical habituation to repetitive stimuli and a mitochondrial component has been put forward. Our group has recently demonstrated a reduction in the high-energy phosphates adenosine triphosphate (ATP) and phosphocreatine (PCr) in the occipital lobe of migraine without aura (MwoA) patients, at least in a subgroup, in a phosphorus MRS ((31)P-MRS) study. In previous studies, basal Lac levels or photic stimulation (PS)-induced Lac levels were found to be increased in patients with migraine with aura (MwA) and migraine patients with visual symptoms and paraesthesia, paresia and/or dysphasia, respectively. The aim of this study was to perform functional (1)H-MRS at 3Â T in 20 MwoA patients and 20 control subjects. Repetitive visual stimulation was applied using MR-compatible...
We reviewed the case history of a 45 year-old women, who presented a pure right sensorimotor stro... more We reviewed the case history of a 45 year-old women, who presented a pure right sensorimotor stroke, due to a left paramedial medullary infarct as result of a left cervical vertebral artery occlusion. The unusual location of the infarct could be explained by the combination of an anatomical variant of the left branch of the anterior spinal artery and the presence of a deep cervical artery, issued from the costo-cervical trunck. This collateral circulation allowed that the lateral and upper medulla was not infarcted.
To investigate the hypothesis that in multilingual speakers different languages are represented i... more To investigate the hypothesis that in multilingual speakers different languages are represented in distinct brain regions, 12 multilingual right-handed men performed a word fluency task, a picture naming task, a comprehension reading task, and their respective control tasks in three languages (Dutch, French, and English) while whole-head functional magnetic resonance imaging (fMRI) was applied. In general, all language tasks revealed predominantly overlapping regions of activation for the different languages. Cerebral activation during use of the foreign languages showed a tendency toward a more extensive recruitment of the areas activated in the native language and the activation of a greater number of regions. Word generation in the foreign languages elicited additional bilateral inferior frontal activation, including Broca's area and left middle temporal gyrus activation; in the native language, additional postcentral activation was found. Picture naming in the foreign langua...
Between January 1992 and July 1998, 320 patients were presurgically evaluated for medically refra... more Between January 1992 and July 1998, 320 patients were presurgically evaluated for medically refractory epilepsy at the University Hospital of Gent. All patients underwent a comprehensive presurgical evaluation, including extensive neurological history and examination, video-EEG monitoring of interictal EEG and habitual seizures, and optimum magnetic resonance (MR). In a large subgroup of these patients, a comprehensive neuropsychological examination and interictal 18FDG-PET were performed. Subsequently, a bilateral carotid angiography and intracarotid amytal procedure (Wada-test) were planned in 49 patients to establish hemispheric language dominance and bilateral memory function. After proper selection, 23 patients underwent invasive video-EEG monitoring with intracranial implantation of parenchymal and/or subdural electrodes to further document the area of seizure onset. From the initial group of 320 potential surgical candidates, 75 patients (42 males, 33 females) with mean age o...
We compared the metabolic information obtained from single-voxel proton MR spectroscopy and posit... more We compared the metabolic information obtained from single-voxel proton MR spectroscopy and positron emission tomography (PET) in patients with temporal lobe epilepsy. Twenty-nine patients with temporal lobe epilepsy were screened for metabolic abnormalities with both proton MR spectroscopy and PET. Lateralization with MR spectroscopy was possible by using NAA/(Cho+Cr) and an asymmetry index. Hypometabolism as determined by PET was classified as typical or complex. Twenty-four (96%) of 25 patients whose seizure onset could be lateralized to one temporal lobe showed ipsilateral lateralization with either MR spectroscopy or PET, whereas concordant lateralization with both techniques was possible only in 14 (56%) of the 25 patients. MR spectroscopy showed 42 abnormal temporal lobes whereas PET showed only 25 lobes with decreased metabolism. All temporal lobes with hypometabolism at PET also had a low NAA/(Cho+Cr). Five patients (20%) with negative PET studies had seizures lateralized c...
Recent and future evolutions in neuroSPECT apply to radiopharmaceuticals techniques and the syner... more Recent and future evolutions in neuroSPECT apply to radiopharmaceuticals techniques and the synergistic use of different imaging modalities in the work-up of neurological disorders. The introduction of Technetium labelled perfusion tracers, which could pass the intact blood-brain barrier, together with the implementation of the tomographic principle, by making the conventional gamma camera rotating, enabled estimation of regional cerebral blood flow and indirectly of local brain metabolism. In addition at present Thallium-201 and Tc-99m sestaMIBI allow functional detection of viable tumor tissue, without interference from previous surgery or radiotherapy as seen using CT-scan or MRI. In neurology this has led to the recognition of SPECT by the American Academy of Neurology (Therapeutics and technology subcommittee) as an established or promising tool in major neurological disorders such as dementia, stroke and epilepsy, while other domains such as brain oncology are considered inves...
PURPOSE/AIM Dynamic arterial spin labeling (dASL) is a non-invasive MR perfusion method able to d... more PURPOSE/AIM Dynamic arterial spin labeling (dASL) is a non-invasive MR perfusion method able to depict global and local states of hypo- and hyperperfusion qualitatively and quantitatively. We illustrate its use in common disease entities with emphasis on cerebrovascular disease and neuro-oncology. Correlation is made with structural MRI, DSC-PWI, MRS and PET. CONTENT ORGANIZATION Concerning cerebrovascular disease, we show cases of ischemia, chronic cerebrovascular occlusive disease, PRES, vasculitis and Moya Moya, as well as the possibility of testing vascular reactivity. Moreover, using a dynamic ASL sequence with 10 time steps, the sequential time evolution in arteriovenous malformations is depicted. In the setting of multimodal tumor imaging, we focus on tumor grading, as well as on treatment follow-up: tumor progression, tumor recurrence and radiation necrosis. SUMMARY Dynamic arterial spin labeling (dASL) is a non-invasive MR perfusion method capable of demonstrating perfusion...
Alzheimer disease (AD), a progressive neurodegenerative disorder, is the most common cause of dem... more Alzheimer disease (AD), a progressive neurodegenerative disorder, is the most common cause of dementia in the elderly. Current consensus statements have emphasized the need for early recognition of AD. In vivo magnetic resonance spectroscopy (MRS) has recently opened new possibilities for noninvasively assessing metabolic and functional correlates of dementia in research and clinical settings. The purpose of this article is to provide a conceptual review, covering the principles of MRS and main pathological findings related to AD. H1 MRS has the possibility of being a neuroimaging marker because the potential clinical applications in patients with AD include a role in early diagnosis and differential diagnosis of AD, a role in prognosis of disease severity, a role in predicting future progression to AD in patients with mild cognitive impairment and tracking disease progression. MRS can also help in the evaluation of treatment effects and in the development of new therapies. In concl...
To find an optimal diagnostic protocol for the presurgical MR evaluation of patients with tempora... more To find an optimal diagnostic protocol for the presurgical MR evaluation of patients with temporal lobe epilepsy. MR imaging in 14 healthy subjects and 25 consecutive patients with temporal lobe epilepsy was performed in paracoronal sections perpendicular to the hippocampi with T1-weighted inversion recovery and T2 weighting. Volume measurements of the hippocampus/amygdala complex were performed and a multiecho sequence yielded T2-calculated images. Hippocampal disease was seen in 22 of 25 temporal lobe epilepsy patients on paracoronal T1-weighted inversion recovery images. Four had bilateral abnormalities. Characteristic for hippocampal disease were features such as volume loss, decreased signal, and loss of internal morphology. Only 17 of 25 patients demonstrated hippocampal pathology on T2-weighted images, and in one patient this was bilateral. Patients with only minimal structural loss on T1-weighted inversion recovery had normal T2-weighted images. T2 calculation was no more se...
All muscles of the neck have a role in motion and postural control of the cervical region. The ai... more All muscles of the neck have a role in motion and postural control of the cervical region. The aim of this study was to investigate the difference in muscle/fat index between (1) cervical flexors and extensors and (2) deep and superficial neck muscles. Twenty-six healthy subjects participated in the study. Magnetic resonance imaging (MRI) was used to quantify muscle fat indices in different cervical flexor and extensor muscles at the C4-C5 level. Overall, the ventral muscles had a significantly lower fat content compared with the dorsal muscles (P < or = 0.001). For the cervical extensors, significant differences between the muscle/fat index of the deep and superficial muscles were found (P < or = 0.001). For the cervical flexors, there were no significant differences between the different muscles. The higher fat content in the dorsal muscles can be explained by a discrepancy in function between the spine extensors and flexors, reflected in a different muscle fiber distributio...
Beta-alanine (BA) supplementation has been shown to augment muscle carnosine concentration, there... more Beta-alanine (BA) supplementation has been shown to augment muscle carnosine concentration, thereby promoting high-intensity (HI) exercise performance. Trained muscles of athletes have a higher increase in carnosine concentration after BA supplementation compared to untrained muscles, but it remains to be determined whether this is due to an accumulation of acute exercise effects or to chronic adaptations from prior training. The aim of the present study was to investigate whether high-volume (HV) and/or HI exercise can improve BA-induced carnosine loading in untrained subjects. All participants (n = 28) were supplemented with 6.4 g/day of BA for 23 days. The subjects were allocated to a control group, HV, or HI training group. During the BA supplementation period, the training groups performed nine exercise sessions, consisting of either 75-90 min continuous cycling at 35-45% Wmax (HV) or 3 to 5 repeats of 30 s cycling at 165% Wmax with 4 min recovery (HI). Carnosine content was measured in soleus and gastrocnemius medialis by proton magnetic resonance spectroscopy. There was no difference in absolute increase in carnosine content between the groups in soleus and gastrocnemius muscle. For the average muscle carnosine content, a higher absolute increase was found in HV (+2.95 mM; P = 0.046) and HI (+3.26 mM; P = 0.028) group compared to the control group (+1.91 mM). However, there was no additional difference between the HV and HI training group. HV and HI exercise training showed no significant difference on BA-induced muscle carnosine loading in soleus and gastrocnemius muscle. It can be suggested that there can be a small cumulative effect of exercise on BA supplementation efficiency, although differences did not reach significance on individual muscle level.
To compare the organ doses and lifetime-attributable risk of cancer for electrocardiogram-trigger... more To compare the organ doses and lifetime-attributable risk of cancer for electrocardiogram-triggered sequential and high-pitch helical scanning in a clinical patient population. Phantom thermoluminiscence dosimeter measurements were used as a model for the organ dose assessment of 314 individual patients who underwent coronary computed tomographic angiography. Patient-specific lifetime-attributable cancer risks were calculated. Phantom measurements showed that heart rate had a significant influence on the delivered radiation exposure in sequential mode, and calcium scoring and contrast bolus tracking scans make a nonnegligible contribution to patients&amp;amp;amp;amp;#39; dose. Therefore, they should be taken into account for patients&amp;amp;amp;amp;#39; organ dose estimations. Median cancer induction risks are low, with 0.008% (0.0016%) and 0.022% (0.056%) for high-pitch and sequential scanning for men (women), respectively. The use of high-pitch helical scanning leads to 65% and 72% lower lifetime-attributable risk values for men and women, respectively, compared with sequential scanning.
To study the value of different parameters derived from single-voxel proton MR spectroscopy of th... more To study the value of different parameters derived from single-voxel proton MR spectroscopy of the mesial temporal lobes in the lateralization of the epileptogenic zone in patients with temporal lobe epilepsy. We studied 12 healthy volunteers and 21 patients with temporal lobe epilepsy refractory to medical treatment, which was clearly lateralized with electroencephalography (EEG) and MR imaging. The mesial temporal lobes were investigated with single-voxel proton MR spectroscopy using a point-resolved spectroscopic sequence with an echo time of 135 milliseconds. The normalized concentration of N-acetylaspartate (NAA), creatine (Cr), and choline-containing compounds (Cho), and the metabolite ratios NAA/Cho+Cr, NAA/Cr, Cho/Cr, and NAA/Cho were calculated from the spectra. Using these values and an asymmetry index, we assigned the patients to one of five lateralization categories. The most consistent MR spectroscopic parameter for clear lateralization was the NAA/Cho+Cr ratio, followe...
Proton magnetic resonance spectroscopy ((1)H-MRS) has been used in a number of studies to assess ... more Proton magnetic resonance spectroscopy ((1)H-MRS) has been used in a number of studies to assess noninvasively the temporal changes of lactate (Lac) in the activated human brain. Migraine neurobiology involves lack of cortical habituation to repetitive stimuli and a mitochondrial component has been put forward. Our group has recently demonstrated a reduction in the high-energy phosphates adenosine triphosphate (ATP) and phosphocreatine (PCr) in the occipital lobe of migraine without aura (MwoA) patients, at least in a subgroup, in a phosphorus MRS ((31)P-MRS) study. In previous studies, basal Lac levels or photic stimulation (PS)-induced Lac levels were found to be increased in patients with migraine with aura (MwA) and migraine patients with visual symptoms and paraesthesia, paresia and/or dysphasia, respectively. The aim of this study was to perform functional (1)H-MRS at 3Â T in 20 MwoA patients and 20 control subjects. Repetitive visual stimulation was applied using MR-compatible...
We reviewed the case history of a 45 year-old women, who presented a pure right sensorimotor stro... more We reviewed the case history of a 45 year-old women, who presented a pure right sensorimotor stroke, due to a left paramedial medullary infarct as result of a left cervical vertebral artery occlusion. The unusual location of the infarct could be explained by the combination of an anatomical variant of the left branch of the anterior spinal artery and the presence of a deep cervical artery, issued from the costo-cervical trunck. This collateral circulation allowed that the lateral and upper medulla was not infarcted.
To investigate the hypothesis that in multilingual speakers different languages are represented i... more To investigate the hypothesis that in multilingual speakers different languages are represented in distinct brain regions, 12 multilingual right-handed men performed a word fluency task, a picture naming task, a comprehension reading task, and their respective control tasks in three languages (Dutch, French, and English) while whole-head functional magnetic resonance imaging (fMRI) was applied. In general, all language tasks revealed predominantly overlapping regions of activation for the different languages. Cerebral activation during use of the foreign languages showed a tendency toward a more extensive recruitment of the areas activated in the native language and the activation of a greater number of regions. Word generation in the foreign languages elicited additional bilateral inferior frontal activation, including Broca's area and left middle temporal gyrus activation; in the native language, additional postcentral activation was found. Picture naming in the foreign langua...
Between January 1992 and July 1998, 320 patients were presurgically evaluated for medically refra... more Between January 1992 and July 1998, 320 patients were presurgically evaluated for medically refractory epilepsy at the University Hospital of Gent. All patients underwent a comprehensive presurgical evaluation, including extensive neurological history and examination, video-EEG monitoring of interictal EEG and habitual seizures, and optimum magnetic resonance (MR). In a large subgroup of these patients, a comprehensive neuropsychological examination and interictal 18FDG-PET were performed. Subsequently, a bilateral carotid angiography and intracarotid amytal procedure (Wada-test) were planned in 49 patients to establish hemispheric language dominance and bilateral memory function. After proper selection, 23 patients underwent invasive video-EEG monitoring with intracranial implantation of parenchymal and/or subdural electrodes to further document the area of seizure onset. From the initial group of 320 potential surgical candidates, 75 patients (42 males, 33 females) with mean age o...
We compared the metabolic information obtained from single-voxel proton MR spectroscopy and posit... more We compared the metabolic information obtained from single-voxel proton MR spectroscopy and positron emission tomography (PET) in patients with temporal lobe epilepsy. Twenty-nine patients with temporal lobe epilepsy were screened for metabolic abnormalities with both proton MR spectroscopy and PET. Lateralization with MR spectroscopy was possible by using NAA/(Cho+Cr) and an asymmetry index. Hypometabolism as determined by PET was classified as typical or complex. Twenty-four (96%) of 25 patients whose seizure onset could be lateralized to one temporal lobe showed ipsilateral lateralization with either MR spectroscopy or PET, whereas concordant lateralization with both techniques was possible only in 14 (56%) of the 25 patients. MR spectroscopy showed 42 abnormal temporal lobes whereas PET showed only 25 lobes with decreased metabolism. All temporal lobes with hypometabolism at PET also had a low NAA/(Cho+Cr). Five patients (20%) with negative PET studies had seizures lateralized c...
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