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Objective: The aims of this study were (1) to examine cerebrovascular autoregulation in subjects with impaired glucose tolerance and type 2 diabetes and (2) to clarify whether cardiovascular autonomic nerve function is associated with abnormal cerebrovascular autoregulation. Research design and methods: Totally, 46 subjects were recruited (12 = impaired glucose tolerance, 17 = type 2 diabetes and 17 = healthy volunteers). Arterial blood flow was assessed within the internal carotid artery at baseline and 20 min after intravenous pharmacological stress (1 g acetazolamide), using quantitative magnetic resonance phase-contrast angiography. Internal carotid artery vascular reactivity and pulsatility index was determined. All subjects underwent baroreceptor reflex sensitivity assessment. Results: Subjects with impaired glucose tolerance and type 2 diabetes had significantly lower internal carotid artery vascular reactivity [40.2%(19.8) and 41.5%(18.7)], respectively, compared with healthy volunteers [57.0%(14.2); analysis of variance, p = 0.02]. There was no significant difference in internal carotid artery vascular reactivity between type 2 diabetes and impaired glucose tolerance groups ( p = 0.84). There was a significant positive correlation between baroreceptor reflex sensitivity (low frequency:high frequency) with cardiac rhythm variability (ρ = 0.47, p = 0.04) and PI (ρ = 0.46, p = 0.04). Conclusion: We have demonstrated significant cerebrovascular haemodynamic abnormalities in subjects with type 2 diabetes and impaired glucose tolerance. This was associated with greater sympathovagal imbalance. This may provide an important mechanistic explanation for increased risk of cerebrovascular disease in diabetes. It also highlights that these abnormalities may already be present in prediabetes.

Background: In vitro studies have shown that the 3-Tesla (T) magnetic resonance (MR) characteristics of high- and standard-molar gadolinium-based contrast agents differ. Such differences may indicate that high-molar (1.0 M) agents offer advantages for perfusion-weighted imaging (PWI) at 3T, as has been previously reported at 1.5T. Purpose: To investigate possible intraindividual differences of high- versus low-molar contrast agents on PWI at 3T in patients with intracranial space-occupying lesions. Material and Methods: Six patients with intraaxial and five patients with extraaxial tumors underwent two MR examinations at 3T, separated by at least 48 hours. On each occasion, an exogenous contrast-based, T2*-weighted, gradient-recalled echo-planar imaging (EPI) technique was used to determine the intracranial perfusion characteristics using one of two intravenous contrast agents: either 5 ml of 1.0 M gadobutrol or 10 ml of 0.5 M gadopentetate dimeglumine. The primary PWI outcome measure was region-of-interest maximal signal change (Cmax). Results: The difference in Cmax for gray and white matter (ΔCmax) was significantly higher for gadobutrol compared to gadopentetate dimeglumine ( Pmax between gray and white matter (rCmax = CmaxGray/CmaxWhite) was also significantly higher (median 24.6%, range 13.7–36.5%) for gadobutrol ( Pmax between the whole tumor and whole normal side hemisphere was higher in five out of the six intraaxial tumor cases. A significantly higher ratio (ΔCmax/Cmax) in the difference between Cmax of gray and white matter (from hemisphere without brain lesion) compared to Cmax for the hemisphere containing the neoplasm (hemisphere with brain lesion) was demonstrated for gadobutrol in intraaxial tumors ( P Conclusion: Higher-concentration 1.0 M gadobutrol can offer advantages over standard 0.5 M gadopentetate dimeglumine, particularly with respect to delineation between gray and white matter and for the demarcation of highly vascularized tumor tissue on brain PWI performed at 3T.

Low grade gliomas (WHO grade II) are diffuse, infiltrative glial tumours of the brain. The low grade glioma group includes a number of entities, namely diffuse astrocytoma, oligodendroglioma and oligoastrocytoma. This group of the low-grade gliomas share certain common issues of behaviour, clinical assessment and management. Even though these tumours are termed low grade they are not to be considered “benign”: untreated they are invariably fatal. They may remain “stable” for many years and hence a “watch and wait” treatment policy is often adopted. Unfortunately some tumours progress more rapidly than others with dedifferentiation into high grade tumours which become rapidly fatal. Based on standard imaging criteria it has been difficult to predict which of these low grade gliomas will progress more rapidly. Treatment decisions would benefit from some prediction as to which tumours are likely to progress more rapidly than others. This review will discuss some of the imaging features that may help to predict which low grade gliomas will progress more rapidly than others. Such imaging features include the rate of growth on serial imaging; the morphological features that parallel genetic markers; the assessment and change of tumour vascular status as assessed by MR perfusion imaging and tumour characteristics on PET and MR spectroscopy.

Purpose: To evaluate post mortem magnetic resonance imaging of the fetus to provide data on the rate of growth of the cerebellum, bony posterior fossa, supratentorial bony compartment and cerebrum. Material and Methods: Twenty fetuses subsequently shown to have normal brain and spines on autopsy were studied using MRI post mortem. MRI from 20 normal pediatric brain examinations in children aged 6 years or younger were studied for comparison. Post mortem MRI was performed using a high‐resolution fast spin echo technique providing T2 weighted images. The area of the cerebellar vermis, posterior fossa, supratentorial skull cavity and cerebral hemispheres was measured in the sagittal plane in all cases. These measurements were compared over the age ranges studied. Results: We have shown that there are differences in the rate of growth and the apparent commencement of growth between the structures under study. The cerebellum appeared to start its significant growth at 16.5 weeks with a rate of 16 mm2/week throughout pregnancy, while the cerebral hemisphere appeared to commence significant growth at 13 weeks at a rate of 184 mm2/week throughout pregnancy. This is in contrast to the bony posterior fossa, whose growth paralleled the supratentorial bony compartment at all ages studied. Conclusion: We interpret our findings as showing relatively late commencement of cerebellar growth compared to the cerebral hemispheres, whereas the growth of the bony posterior fossa appears to be in advance and independent of cerebellar growth. Our results support the hypothesis that posterior fossa development depends on raised hydrostatic pressure in the CSF containing structures of the posterior fossa. When this mechanism fails, as in some cases of myelomeningocoele, a small posterior fossa is formed which characterizes the Chiari 2 malformation.

Purpose: To compare the diagnostic information obtained from ultrafast MR imaging with standard MR imaging techniques in pediatric neuroradiology. The goal was to judge whether ultrafast methods can be used to replace standard methods and reduce the need for sedation or general anesthesia as a result of the considerably shorter scan times.Material and Methods: Our prospective study involved 125 patients. Routine clinical imaging was performed along with two ultrafast methods. Single shot fast spin echo (SSFSE) was used to give T2-weighted images and an echo planar imaging (EPI) sequence to provide a T1-weighted images.The ultrafast images were presented to an experienced neuroradiologist who was also given the information present on the initial referral card. These reports based on the ultrafast images were then compared with the formal radiologic report made solely on the basis of the standard imaging.Results: The overall sensitivity and specificity for ultrafast imaging when compared to the reference st...

Purpose: To evaluate any possible advantages of high-concentration gadolinium chelates in the human brain thin-slice MR. Material and Methods: Thirty-six patients were allocated into six groups. Three groups had perfusion imaging performed using 7-mm-thick slices and the other three groups had 4-mm-thick slices. One group who had 7-mm slices and one group of 4-mm slices had 0.5 M gadolinium (20 ml) whilst other groups received the high-concentration gadolinium (1.0 M: 10 ml and 20 ml). The time-intensity curves were analysed for maximum signal reduction and signal-to-noise measurements. Results: Twenty ml of the 1.0-M agent produced significantly increased maximum signal change and improvement in signal-to-noise when compared to 20 ml of 0.5 M. There was no significant difference between the maximum signal change when 20 ml of 0.5 M and 10 ml of 1.0 M agents were compared. There was no significant difference between the maximum signal changes when 7-mm and 4-mm slice thickness using the same dosing regimens. Conclusion: Four-mm slice thickness perfusion imaging can be performed with high-concentration gadolinium in the human brain and we discuss the advantages of this.

This article reviews the concepts of cerebral blood flow for the clinician involved in the management of patients with carotid stenosis and/or ischaemic stroke. Methods of assessing cerebral blood flow in vivo using nuclear medicine, magnetic resonance and X-ray computed tomography are described. Applications of magnetic resonance and X-ray computed tomographic methods are reviewed and illustrated by examples from the authors' radiological practice.

Purpose: To evaluate the role of standard and ultrafast MR brain imaging and compare the information with CT. Material and Methods: This was a prospective study of 114 patients with acute neurological symptoms and signs. CT brain examinations consisted of axial non-enhanced images. MR imaging consisted of standard spin-echo/fast spin-echo sequences and a series of rapid techniques including echoplanar and single shot fast spin-echo sequences. Results: Using standard MR methods, 41% of the patients had all five sequences of good technical quality, while using ultrafast methods 81% of the patients had good technical quality examinations in all five sequences. In 3% of the cases, ischaemic stroke was incorrectly reported on CT. In 24% of the cases, MR gave extra diagnostic information not reported on CT and in a further 8%, one neuroradiologist reported the abnormality in agreement with the MR, whilst the other neuroradiologist reported the CT as normal. In 2 cases, subarachnoid haemorrhage was missed on MR. Subarachnoid haemorrhage was not shown on the ultrafast sequences. Conclusion: MR can be used to image acute neurological admissions with a high success rate, particularly using ultrafast methods. In many cases, MR provided extra information of direct clinical relevance not shown on CT.