Cortical thickness following electroconvulsive therapy in patients with depression: a longitudinal MRI study

OBJECTIVE

Several studies have found an increase in hippocampal volume following electroconvulsive therapy (ECT), but the effect on cortical thickness has been less investigated. We aimed to examine the effects of ECT on cortical thickness and their associations with clinical outcome.

METHOD

Using 3 Tesla MRI scanner, we obtained T1-weighted brain images of 18 severely depressed patients at three time points: before, right after and 6 months after a series of ECT. The thickness of 68 cortical regions was extracted using Free Surfer, and Linear Mixed Model was used to analyze the longitudinal changes.

RESULTS

We found significant increases in cortical thickness of 26 regions right after a series of ECT, mainly within the frontal, temporal and insular cortex. The thickness returned to the baseline values at 6-month follow-up. We detected no significant decreases in cortical thickness. The increase in the thickness of the right lateral orbitofrontal cortex was associated with a greater antidepressant effect, r = 0.75, P = 0.0005. None of the cortical regions showed any associations with cognitive side effects.

CONCLUSION

The increases in cortical thickness induced by ECT are transient. Further multimodal MRI studies should examine the neural correlates of these increases and their relationship with the antidepressant effect.

Cerebral blood flow, oxygen metabolism, and lactate during hypoxia in patients with obstructive sleep apnea

Study Objectives

Obstructive sleep apnea (OSA) is associated with increased risk of stroke but the underlying mechanism is poorly understood. We suspect that the normal cerebrovascular response to hypoxia is disturbed in patients with OSA.

Methods

Global cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and lactate concentration during hypoxia were measured in patients with OSA and matched controls. Twenty-eight patients (82.1% males, mean age 52.3 ± 10.0 years) with moderate-to-severe OSA assessed by partial polysomnography were examined and compared with 19 controls (73.7% males, mean age 51.8 ± 10.1 years). Patients and controls underwent magnetic resonance imaging (MRI) during 35 min of normoxia followed by 35 min inhaling hypoxic air (10%-12% O2). After 3 months of continuous positive airway pressure (CPAP) treatment, 22 patients were rescanned.

Results

During hypoxia, CBF significantly increased with decreasing arterial blood oxygen concentration (4.53 mL (blood)/100 g/min per -1 mmol(O2)/L, p < 0.001) in the control group, but was unchanged (0.89 mL (blood)/100 g/min per -1 mmol(O2)/L, p = 0.289) in the patient group before CPAP treatment. The CBF response to hypoxia was significantly weaker in patients than in controls (p = 0.003). After 3 months of CPAP treatment the CBF response normalized, showing a significant increase during hypoxia (5.15 mL (blood)/100 g/min per -1 mmol(O2)/L, p < 0.001). There was no difference in CMRO2 or cerebral lactate concentration between patients and controls, and no effect of CPAP treatment.

Conclusions

Patients with OSA exhibit reduced CBF in response to hypoxia. CPAP treatment normalized these patterns.

Acute Unilateral Papillitis versus Retrobulbar Neuritis: Relation to Multiple Sclerosis

Prospectively referred patients with unilateral acute optic neuritis (ON) (n=223; aged 12–57; 158 women), either idiopathic or part of clinically definite multiple sclerosis (CDMS), were systematically examined by the same physician. We analysed whether the 161 patients with retrobulbar neuritis and the 62 patients with papillitis differed from each other clinically or according to paraclinical tests. The following characteristics were observed in retrobulbar ON respectively papillitis: median age 33 and 33 years, women 70% and 73%, clinically definite MS 30% and 27%. Abnormal results in retrobulbar ON and in papillitis (indicated in brackets) did not differ significantly and were found as follows: cerebral MRI in 56% (63%), VEP from the eye with acute ON in 82% (88%), VEP from the eye without acute ON in 38% (33%), SEP from median nerves in 9% (10%), SEP from tibial nerves in 22% (22%) and biotesiometry in 32% (27%). In the CSF, oligoclonal bands were present in 42% (53%), increased IgG-index in 40% (44%) and increased leucocyte count in 39% (29%). The HLA-DR15 tissue type was present in 47% (43%). There were no significant differences between retrobulbar ON and papillitis when the idiopathic cases and cases with clinically definite MS were analysed separately. Our data document that unilateral retrobulbar ON and papillitis are both part of the MS spectrum and not different from each other with regard to clinical and paraclinical parameters, indicating that the two groups can be pooled in future treatment trials.

Chemical Shift Selective Magnetic Resonance Imaging of the Optic Nerve in Patients with Acute Optic Neuritis

Optic neuritis is often the first manifestion of multiple sclerosis (MS). Sixteen patients with acute optic neuritis and one patient with benign intracranial hypertension (BIH) were investigated by magnetic resonance imaging, using a chemical shift selective double spin echo sequence. In 3 of the 16 patients, abnormalities were seen. In one patient with bilateral symptoms, signal hyperintensity and swelling of the right side of the chiasm were found. In another patient the optic nerve was found diffusely enlarged with only a marginally increased signal in the second echo. In the third patient an area of signal hyperintensity and swelling was seen in the left optic nerve. In the patient with BIH the subarachnoid space which surrounds the optic nerves was enlarged. Even using this refined pulse sequence, avoiding the major artefact in imaging the optic nerve, the chemical shift artefact, lesions were only shown in 3/16 (19%) of the patients with optic neuritis. Nevertheless, the presented chemical shift selective double spin echo sequence may be of great value for detection of retrobulbar lesions.

Functional Mr Imaging at 1.5 T

A preliminary investigation of the effects of stimulation of the visual and the motor cortex was made on a conventional 1.5 T MR imaging scanner. Both types of activation gave a detectable change in the signal between rest and stimulation using a gradient echo sequence with an echo time of 60 ms. The observed effects were assumed to be caused by variation in the amount of paramagnetic deoxyhemoglobin between stimulation and rest due to local increase of capillary blood flow in the human brain during stimulation.

Evaluation of Biexponential Relaxation Processes by Magnetic Resonance Imaging

Despite the complexity of biologic tissues, a monoexponential behaviour is usually assumed when estimating relaxation processes in vivo by magnetic resonance imaging (MRI). This study was designed to evaluate the potential of biexponential decomposition of T1 and T2 relaxation curves obtained at 1.5 tesla (T). Measurements were performed on a phantom of bicompartmental perspex boxes with combinations of different CuSO4 concentrations. T1 determination was based on a 12-points partial saturation inversion recovery pulse sequence. T2 determination was provided by a multiple spin echo sequence with 32 echoes. Applying biexponential curve analysis, a significant deviation from a monoexponential behaviour was recognized at a ratio of corresponding relaxation rates of about 3 and 2, estimating T1 and T2 relaxation, respectively (p<0.01, F-test). Requiring an SD≤10 per cent for each set of parameters, the biexponential model was accepted when this ratio exceeded a factor of 5 and 8, respectively. Referring to ‘expected’ T1 and T2 values, however, an accuracy within 20 per cent only was observed at ratios of at least 6 and 15. It is concluded that quantitative estimation of individual and specific relaxation components in complex biologic tissues by MRI may prove very difficult.

Deuterium MR Spectroscopy at 4.7 T

Deuterium MR spectroscopy was used for the determination of tissue blood flow (TBF). The tracer D2O was injected into the tissue of interest, and tracer washout was followed using a 4.7 T spectroscopy/imaging unit. Normal subcutaneous tissue in rats was studied, as well as tissue influenced by vasoactive agents (papaverine and adrenaline). The vasoactive agents introduced changes of 40% in TBF, compared with normal tissue. Normal tissue measurements were repeated using various D2O injection volumes (5–400 μl). The injection volume 5 μl gave TBF 11.7 ± 2.0 ml/100 g·min (mean ± 1 SD). This value was 40% higher than corresponding values observed at larger injection volumes (200–400 μl). This injection volume effect is probably partly due to a capillary dilution caused by tracer administration, and partly related to the non-physiological deuterium signal decrease observed in dead rats. Blood flow measurements in human colon tumours implanted in nude mice showed a rather poor reproducibility, not improved by the use of a multiple site injection technique.

Age Dependent White Matter Lesions and Brain Volume Changes in Healthy Volunteers

The brain of 142 healthy volunteers aged 21 to 80 years were investigated using MR imaging. The number and size of the white matter hyperintensity lesions (WMHL) in the cerebral hemispheres were determined. Furthermore, the volume of the cerebral hemispheres and of the lateral ventricles was measured. An almost linear increase in the number of volunteers with WMHL was seen with aging for males and females. With aging a significant decrease in the volume of the cerebral hemispheres was found for males, and a significant increase in the volume of the lateral ventricles was seen for both males and females. Our results suggest that with aging central atrophy increases more (relatively) than cortical atrophy. No correlation was found between the decreasing volume of the cerebral hemispheres and the increasing number and size of WMHL, nor between the increasing volume of the lateral ventricles and the increasing number and size of WMHL.

Cerebrospinal fluid levels of chitinase 3-like 1 and neurofilament light chain predict multiple sclerosis development and disability after optic neuritis

BACKGROUND

Cerebrospinal fluid (CSF) biomarkers have been suggested to predict multiple sclerosis (MS) after clinically isolated syndromes, but studies investigating long-term prognosis are needed.

OBJECTIVE

To assess the predictive ability of CSF biomarkers with regard to MS development and long-term disability after optic neuritis (ON).

METHODS

Eighty-six patients with ON as a first demyelinating event were included retrospectively. Magnetic resonance imaging (MRI), CSF leukocytes, immunoglobulin G index and oligoclonal bands were registered. CSF levels of chitinase-3-like-1, osteopontin, neurofilament light-chain, myelin basic protein, CCL2, CXCL10, CXCL13 and matrix metalloproteinase-9 were measured by enzyme-linked immunosorbent assay. Patients were followed up after 13.6 (range 9.6-19.4) years and 81.4% were examined, including Expanded Disability Status Scale and MS functional composite evaluation. 18.6% were interviewed by phone. Cox regression, multiple regression and Spearman correlation analyses were used.

RESULTS

Forty-six (53.5%) developed clinically definite MS (CDMS) during follow-up. In a multivariate model MRI (p=0.0001), chitinase 3-like 1 (p=0.0033) and age (p=0.0194) combined predicted CDMS best. Neurofilament light-chain predicted long-term disability by the multiple sclerosis severity scale (p=0.0111) and nine-hole-peg-test (p=0.0202). Chitinase-3-like-1 predicted long-term cognitive impairment by the paced auditory serial addition test (p=0.0150).

CONCLUSION

Neurofilament light-chain and chitinase-3-like-1 were significant predictors of long-term physical and cognitive disability. Furthermore, chitinase-3-like-1 predicted CDMS development. Thus, these molecules hold promise as clinically valuable biomarkers after ON as a first demyelinating event.

Exercise training favors increased insulin-stimulated glucose uptake in skeletal muscle in contrast to adipose tissue: a randomized study using FDG PET imaging

Physical exercise increases peripheral insulin sensitivity, but regional differences are poorly elucidated in humans. We investigated the effect of aerobic exercise training on insulin-stimulated glucose uptake in five individual femoral muscle groups and four different adipose tissue regions, using dynamic (femoral region) and static (abdominal region) 2-deoxy-2-[¹⁸F]fluoro-d-glucose (FDG) PET/CT methodology during steady-state insulin infusion (40 mU·m⁻²·min⁻¹). Body composition was measured by dual X-ray absorptiometry and MRI. Sixty-one healthy, sedentary [V(O2max) 36(5) ml·kg⁻¹·min⁻¹; mean(SD)], moderately overweight [BMI 28.1(1.8) kg/m²], young [age: 30(6) yr] men were randomized to sedentary living (CON; n = 17 completers) or moderate (MOD; 300 kcal/day, n = 18) or high (HIGH; 600 kcal/day, n = 18) dose physical exercise for 11 wk. At baseline, insulin-stimulated glucose uptake was highest in femoral skeletal muscle followed by intraperitoneal visceral adipose tissue (VAT), retroperitoneal VAT, abdominal (anterior + posterior) subcutaneous adipose tissue (SAT), and femoral SAT (P < 0.0001 between tissues). Metabolic rate of glucose increased similarly (~30%) in the two exercise groups in femoral skeletal muscle (MOD 24[9, 39] μmol·kg⁻¹·min⁻¹, P = 0.004; HIGH 22[9, 35] μmol·kg⁻¹·min⁻¹, P = 0.003) (mean[95% CI]) and in five individual femoral muscle groups but not in femoral SAT. Standardized uptake value of FDG decreased ~24% in anterior abdominal SAT and ~20% in posterior abdominal SAT compared with CON but not in either intra- or retroperitoneal VAT. Total adipose tissue mass decreased in both exercise groups, and the decrease was distributed equally among subcutaneous and intra-abdominal depots. In conclusion, aerobic exercise training increases insulin-stimulated glucose uptake in skeletal muscle but not in adipose tissue, which demonstrates some interregional differences.

Dilation by CGRP of middle meningeal artery and reversal by sumatriptan in normal volunteers

BACKGROUND

Calcitonin gene-related peptide (CGRP) plays a fundamental role in the pathophysiology of neurovascular headaches. CGRP infusion causes headache and dilation of cranial vessels. However, it is unknown to what extent CGRP-induced vasodilation contributes to immediate head pain and whether the migraine-specific abortive drug sumatriptan, a 5-hydroxytryptamine 1B/1D agonist, inhibits CGRP-induced immediate vasodilation and headache.

METHODS

We performed a double-blind, randomized, placebo-controlled, crossover study in 18 healthy volunteers. We recorded circumference changes of the middle meningeal artery (MMA) and middle cerebral artery (MCA) using magnetic resonance angiography before and after infusion (20 minutes) of 1.5 μg/min human αCGRP or placebo (isotonic saline) as well as after a 6-mg sumatriptan subcutaneous injection.

RESULTS

Compared with placebo, CGRP caused significant dilation of MMA (p = 0.006) and no dilation of MCA (p = 0.69). Sumatriptan caused a marked contraction of MMA (15%-25.2%) and marginal contraction of MCA (3.9% to 5.3%). Explorative analysis revealed that sumatriptan had a more selective action on MMA compared with MCA on the CGRP day (p < 0.0001) and on the placebo day (p = 0.007).

CONCLUSION

These data suggest that exogenous CGRP dilates extracranial vessels and not intracranial, and that sumatriptan exerts part of its antinociceptive action by constricting MMA and not MCA.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that IV GCRP causes dilation of the MMA but not the MCA in healthy volunteers, and that sumatriptan reverses the dilation of the MMA caused by CGRP.

The value of conventional high-field MRI in MS in the light of the McDonald criteria: a literature review

The diagnosis of MS is based on the revised McDonald criteria and is multidisciplinary. Both clinical and paraclinical measures are included. High-field magnetic resonance imaging (MRI) is becoming increasingly available and it is therefore necessary to clarify possible advantages of high-field MRI in MS. The aim of this paper was to review MRI studies in MS where a direct comparison of MRI at high field with MRI at 1-1.5 tesla (T) had been performed. The studies evaluated were found by searching Pubmed with relevant terms including MeSH terms. The reviewed studies all found the conspicuity of lesions to be better at high field. Of the seven studies, six found more and bigger lesions at high-field MRI. In the present paper, the relevant MRI sequences are evaluated in detail. The detection of more lesions at high-field strength did not seem to lead to earlier diagnosis of clinically definite multiple sclerosis. Further larger studies of patients with clinically isolated syndromes are needed to settle the question of a diagnostic consequence of high-field imaging in MS. We suggest that the next revision of the McDonald diagnostic criteria include a recommendation of field strength.

Unsupervised motion-compensation of multi-slice cardiac perfusion MRI

This paper presents a novel method for registration of single and multi-slice cardiac perfusion MRI. Utilising off-line computer intensive analyses of variance and clustering in an annotated training set, the presented method is capable of providing registration without any manual interaction in less than a second per frame. Changes in image intensity during the bolus passage are modelled by a slice-coupled active appearance model, which is augmented with a cluster analysis of the training set. Landmark correspondences are optimised using the MDL framework due to Davies et al. Image search is verified and stabilised using perfusion specific prior models of pose and shape estimated from training data. Qualitative and quantitative validation of the method is carried out using 2000 clinical quality, short-axis, perfusion MR slice images, acquired from 10 freely breathing patients with acute myocardial infarction. Despite evident perfusion deficits and varying image quality in the limited training set, a leave-one-out cross-validation of the method showed a mean point to curve distance of 1.25+/-0.36 pixels for the left and right ventricle combined. We conclude that this learning-based method holds great promise for the automation of cardiac perfusion investigations, due to its accuracy, robustness and generalisation ability.

Left ventricular dysfunction in normotensive Type 1 diabetic patients: the impact of autonomic neuropathy

AIMS

The pathophysiological mechanisms responsible for increased cardiovascular mortality in diabetic autonomic neuropathy (AN) are largely unknown. The aim was to determine the relative role of AN in the pathogenesis of cardiac diastolic dysfunction and left ventricular hypertrophy in Type 1 diabetes.

METHODS

Ten Type 1 diabetic patients with AN, defined by cardiovascular tests (AN+) and 10 age- and sex-matched patients without neuropathy (AN-) as well as 10 healthy subjects (C) participated in the study. Left ventricular diastolic function was assessed by Doppler echocardiography, whilst systolic function was evaluated by cine magnetic resonance (MR) imaging.

RESULTS

Doppler echocardiography showed a significant decrease in E/A ratio, i.e. the ratio between peak Early transmitral filling velocity during early diastole (E-wave) and peak transmitral Atrial filling velocity during late diastole (A-wave), in AN+ compared with C (P < 0.01) [0.95 +/- 0.08 (mean +/- sem) (AN+); 1.19 +/- 0.09 (AN-); 1.33 +/- 0.10 (C)]. The E-wave deceleration time was significantly shorter in AN+ compared with AN- and C (P < 0.02) [178 +/- 7 ms (AN+); 203 +/- 9 ms (AN-); 205 +/- 9 ms (C)]. Cine MR imaging showed a significantly greater left ventricular mass index in AN+ compared with C [103 +/- 4 g/m(2) (AN+) vs. 98 +/- 7 (AN-) and 92 +/- 4 g/m(2) (C), P < 0.05].

CONCLUSION

Autonomic neuropathy is associated with left ventricular hypertrophy and diastolic dysfunction in Type 1 diabetic patients.

Nitric oxide synthase expression and enzymatic activity in multiple sclerosis

We used post-mortem magnetic resonance imaging (MRI) guidance to obtain paired biopsies from the brains of four patients with clinical definite multiple sclerosis (MS). Samples were analyzed for the immunoreactivity (IR) of the three nitric oxide (NO) synthase isoforms [inducible, neuronal and endothelial nitric oxide synthase (NOS)], and enzymatic NO synthase activity. MRI guided biopsies documented more active plaques than macroscopic examination, and histological examination revealed further lesions. Inducible NOS (iNOS) was the dominant IR isoform, while reactive astrocytes were the dominant iNOS expressing cells in active lesions. NOS IR expressing cells were widely distributed in plaques, in white and gray matter that appeared normal macroscopically, and on MR. Endothelial NOS (eNOS) was highly expressed in intraparenchymal vascular endothelial cells of MS patients. A control group matched for age and sex showed no such changes. Our data support the hypothesis that NO is a pathogenic factor in MS, and that NOS IR is strongly expressed in brain regions appearing normal by MRI.

Gadolinium-enhanced magnetic resonance imaging predicts response to methylprednisolone in multiple sclerosis

Oral high-dose methylprednisolone treatment is efficacious in acute optic neuritis (ON) and attacks of multiple sclerosis (MS). The responses to treatment in subgroups of patients participating in two randomized, controlled trials were assessed. Fifty-eight patients with ON and 51 patients with attacks of MS were treated with placebo or oral methylprednisolone (500 mg daily for five days with a 10-day tapering period). A gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) scan was obtained at baseline in 66 patients, and 29 patients underwent repeated MRI studies. Seventy-four patients underwent lumbar puncture before treatment. The odds ratio (OR) of improvement after methylprednisolone treatment (a one point change in the visual function system score of the Kurtzke Expanded Disability Status Scale (EDSS) in ON or in the EDSS score in attacks of MS) was higher in patients with enhancing lesions on baseline MRI (one week: OR 15, P = 0.02; eight weeks: OR 4.6, P = 0.02). Methylprednisolone treatment suppressed Gd-enhancement after one week (P < 0.001) and three weeks (P = 0.001). Cerebrospinal fluid measures of intrathecal inflammation correlated with the area of Gd-enhancement but did not correlate as closely with the treatment response as did the results of Gd-enhanced MRI. These findings suggest that the resolution of intrathecal inflammation as assessed by Gd-enhanced MRI is a major effect of oral high-dose methylprednisolone.

Perfusion quantification using Gaussian process deconvolution

The quantification of perfusion using dynamic susceptibility contrast MRI (DSC-MRI) requires deconvolution to obtain the residual impulse response function (IRF). In this work, a method using the Gaussian process for deconvolution (GPD) is proposed. The fact that the IRF is smooth is incorporated as a constraint in the method. The GPD method, which automatically estimates the noise level in each voxel, has the advantage that model parameters are optimized automatically. The GPD is compared to singular value decomposition (SVD) using a common threshold for the singular values, and to SVD using a threshold optimized according to the noise level in each voxel. The comparison is carried out using artificial data as well as data from healthy volunteers. It is shown that GPD is comparable to SVD with a variable optimized threshold when determining the maximum of the IRF, which is directly related to the perfusion. GPD provides a better estimate of the entire IRF. As the signal-to-noise ratio (SNR) increases or the time resolution of the measurements increases, GPD is shown to be superior to SVD. This is also found for large distribution volumes.

Functional MRI of the visual cortex and visual testing in patients with previous optic neuritis

The volume of cortical activation as detected by functional magnetic resonance imaging (fMRI) in the visual cortex has previously been shown to be reduced following optic neuritis (ON). In order to understand the cause of this change, we studied the cortical activation, both the size of the activated area and the signal change following ON, and compared the results with results of neuroophthalmological testing. We studied nine patients with previous acute ON and 10 healthy persons served as controls using fMRI with visual stimulation. In addition to a reduced activated volume, patients showed a reduced blood oxygenation level dependent (BOLD) signal increase and a greater asymmetry in the visual cortex, compared with controls. The volume of visual cortical activation was significantly correlated to the result of the contrast sensitivity test. The BOLD signal increase correlated significantly to both the results of the contrast sensitivity test and to the Snellen visual acuity. Our results indicate that fMRI is a useful method for the study of ON, even in cases where the visual acuity is severely impaired. The reduction in activated volume could be explained as a reduced neuronal input; however, the greater asymmetry might point to a cortical reorganization as a consequence of neuronal damage. Future fMRI studies in ON will add to the understanding of the neural adaptive behaviour following ON.

Cerebral perfusion and cerebrovascular reactivity are reduced in white matter hyperintensities

BACKGROUND AND PURPOSE

There is growing evidence that white matter hyperintensities (WMH) should not be considered as benign age-dependent changes on MR images but indicate pathological changes with clinical consequences. Previous studies comparing subjects with WMH to normal controls have reported global reductions in cerebral blood flow (CBF) and cerebral vascular reactivity. In this study, we examined localized hemodynamic status to compare WMH to normal appearing white matter (NAWM).

METHODS

A group of 21 normal 85-year-old subjects were studied using dynamic contrast-enhanced MRI together with administration of acetazolamide. From a combination of anatomic images with different signal weighting, regions of interest were generated corresponding to gray and white matter and WMH. Localized measurements of CBF and cerebral blood volume (CBV) and mean transit time were obtained directly within WMH and NAWM.

RESULTS

When comparing WMH to NAWM, measurements showed significantly lower CBF (P=0.004) and longer mean transit time (P< 0.001) in WMH but no significant difference in CBV (P=0.846). The increases in CBF and CBV induced by acetazolamide were significantly smaller in WMH than in NAWM (P=0.026, P<0.001).

CONCLUSION

These results show that a change in the hemodynamic status is present within the WMH, making these areas more likely to be exposed to transient ischemia inducing myelin rarefaction. In the future, MRI may be used to examine the effect of therapeutic strategies designed to prevent or normalize vascular changes.

Visual cortex reactivity in sedated children examined with perfusion MRI (FAIR)

Sleeping and sedated children can respond to visual stimulation with a decrease in blood oxygenation level dependent (BOLD) functional MRI signal response. The contribution of metabolic and hemodynamic parameters to this inverse signal response is incompletely understood. It has been hypothesized that it is caused by a relatively greater increase of oxygen consumption compared to rCBF (regional cerebral blood flow) increase. We studied the rCBF changes during visual stimulation in four sedated children, aged 4-71 months, and four alert adults, with an arterial water spin labeling technique (FAIR) and BOLD fMRI in a 1.5T MR scanner. In the children, FAIR signal decreased by a mean of 0.96% (range 0.77-1.05) of the baseline periods of the non-selective images, while BOLD signal decreased by 2.03% (range 1.99-2.93). In the adults, FAIR and BOLD signal increased by 0.88% (range 0.8-0.99) and 2.63% (range 1.99-2.93), respectively. Thus, in the children, an rCBF increase could not be detected by perfusion MRI, but indications of a FAIR signal decrease were found. An rCBF decrease in the primary visual cortex during stimulation has not been reported previously, but it is a possible explanation for the negative BOLD response. Future studies will have to address if this response pattern is a consequence of age or sleep/sedation.