<CLINICAL>Atraumatic restoration in amelogenesis imperfecta using flowable composite resin

Amelogenesis imperfecta causes defects in the tooth enamel. These defects can appear as small pits or dents in the tooth or can be so widespread as to make the entire tooth small in size and/or mis-shaped. This may result in tooth sensitivity, an unsightly appearance and/or increased susceptibility to dental caries. Here, we report a case of a patient exhibiting amelogenesis imperfecta, the treatment employed to treat the defects, and the result obtained. The affected teeth (all upper teeth) appeared white and the patient requested esthetic improvement of the appearance. We applied flowable composite resin to the hypomineralized defect. The result was dramatic improvement in tooth color of the upper incisors and first premolars. We conclude that atraumatic flowable composite resin restorations are useful in the treatment of amelogenesis imperfecta defects

Comparison of cerebral blood flow estimates in the ischemic area of rat brain obtained with dynamic susceptibility contrast and continuous arterial spin labeling

Gadolinium (Gd) based dynamic susceptibility contrast (DSC) agents allow brain perfusion NMR images in both animal and human [1,2,3,4]. It is not easy to model the arterial input function (AIF) in small animals because of the small ratio of artery to tissue in a voxel. Hence, cerebral blood flow (CBF) values estimated from DSC images can be inaccurate. As an alternative, the maximum value of the logarithmic signal ratio (maxDELTA R2*) is occasionally used as an indicator of the CBF in the rat brain [3,4]. To investigate the accuracy of CBF indicated by maxDELTA R2* in the ischemic rat brain, a comparison of the CBF values obtained with continuous arterial spin labeling (CASL) and maxDELTA R2* was performed in an ischemic rat model.International Society for Magnetic Resonance in Medicine(ISMRM) 14th Scientific Meeting and Exhibitio

Relationship between Baseline Cerebral Blood Flow and Vascular Responses to Changes in PaCO2 Measured by Positron Emission Tomography in Humans:Implication of Inter-individual Variations of Cerebral Vascular Tone

AIM: Inter-individual variations in normal human cerebral blood flow (CBF) at rest condition have been reported. Inter-individual variation of cerebral vascular tone is considered to contribute to this, and several determinants of cerebral vascular tone have been proposed. In the present study, the relationship between CBF and cerebral vascular tone to inter-individual variation at rest condition was investigated using positron emission tomography (PET). METHODS: CBF was measured using PET with H(2) (15)O in each of 20 healthy subjects (20-28 years) under three conditions: at rest (baseline), during hypercapnia and during hypocapnia. The vascular response to change in P(a)CO(2) was calculated as the percentage changes in CBF per absolute change in P(a)CO(2) in response to hypercapnia and hypocapnia. RESULTS: A significant negative correlation between baseline CBF and the vascular response to hypocapnia was observed in the thalamus, temporal cortex, parietal cortex, occipital cortex and cerebral cortex (P < 0.05). A trend towards negative correlation between baseline CBF and the vascular response to hypocapnia was observed in the cerebellum and putamen (P < 0.1). A significant negative correlation between baseline CBF and the vascular response to hypercapnia was observed in the occipital cortex (P < 0.05). No significant correlation was observed between baseline CBF and haemoglobin concentration, and P(a)CO(2). CONCLUSION: These findings support the assumption that cerebral vascular tone might incline towards vasoconstriction and vasodilatation when baseline CBF is low and high between individuals respectively. Although several determinants of cerebral vascular tone have been proposed, the mechanism of such inter-individual differences in cerebral vascular tone is unknown

Cerebral vascular mean transit time in healthy humans: a comparative study with PET and dynamic susceptibility contrast-enhanced MRI.

Cerebral vascular mean transit time (MTT), defined as the ratio of cerebral blood volume to cerebral blood flow (CBV/CBF), is a valuable indicator of the cerebral circulation. Positron emission tomography (PET) and dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) are useful for the quantitative determination of MTT in the clinical setting. The aim of this study was to establish a normal value set of MTT as determined by PET and by DSC-MRI and to identify differences between these methods. Seven healthy volunteers were studied with (15)O-PET (H(2)(15)O and C(15)O) and gradient-echo echo-planar DSC-MRI at 1.5 T. In the DSC-MRI study with bolus injection of contrast agent, deconvolution analysis was performed. Comparison of gray-to-white matter ratios showed fairly good agreement between PET and DSC-MRI for all parameters (relative CBV, relative CBF, and relative MTT), confirming the validity of relative measurements with DSC-MRI. However, quantitative MTT measured by DSC-MRI was significantly shorter than that measured by PET in cerebral cortical regions (2.8 to 3.0 secs for DSC-MRI versus 3.9 to 4.3 secs for PET) and the centrum semiovale (3.5 secs for DSC-MRI versus 4.8 secs for PET). These discrepancies may be because of the differences in the intrinsic sensitivity of each imaging modality to vascular components; whereas PET measurement of CBV is equally sensitive to all vascular components, measurement with DSC-MRI originates from the microvasculature in the vicinity of the brain parenchyma. This underlying difference may influence interpretation of MTT determined by PET or by DSC-MRI for patients with cerebrovascular disease

Influence of O-methylated metabolite penetrating the blood-brain barrier to estimation of dopamine synthesis capacity in human L-[β-(11)C]DOPA PET.

O-methyl metabolite (L-[β-(11)C]OMD) of (11)C-labeled L-3,4-dihydroxyphenylalanine (L-[β-(11)C]DOPA) can penetrate into brain tissue through the blood-brain barrier, and can complicate the estimation of dopamine synthesis capacity by positron emission tomography (PET) study with L-[β-(11)C]DOPA. We evaluated the impact of L-[β-(11)C]OMD on the estimation of the dopamine synthesis capacity in a human L-[β-(11)C]DOPA PET study. The metabolite correction with mathematical modeling of L-[β-(11)C]OMD kinetics in a reference region without decarboxylation and further metabolism, proposed by a previous [(18)F]FDOPA PET study, were implemented to estimate radioactivity of tissue L-[β-(11)C]OMD in 10 normal volunteers. The component of L-[β-(11)C]OMD in tissue time-activity curves (TACs) in 10 regions were subtracted by the estimated radioactivity of L-[β-(11)C]OMD. To evaluate the influence of omitting blood sampling and metabolite correction, relative dopamine synthesis rate (kref) was estimated by Gjedde-Patlak analysis with reference tissue input function, as well as the net dopamine synthesis rate (Ki) by Gjedde-Patlak analysis with the arterial input function and TAC without and with metabolite correction. Overestimation of Ki was observed without metabolite correction. However, the kref and Ki with metabolite correction were significantly correlated. These data suggest that the influence of L-[β-(11)C]OMD is minimal for the estimation of kref as dopamine synthesis capacity.Journal of Cerebral Blood Flow & Metabolism advance online publication, 6 November 2013; doi:10.1038/jcbfm.2013.187

Impact of spillover from white matter by partial volume effect on quantification of amyloid deposition with [(11)C]PiB PET.

High non-specific uptake of [(11)C]Pittsburgh compound B ([(11)C]PiB) in white matter and signal spillover from white matter, due to partial volume effects, confound radioactivity measured in positron emission tomography (PET) with [(11)C]PiB. We aimed to reveal the partial volume effect in absolute values of kinetic parameters for [(11)C]PiB, in terms of spillover from white matter. Dynamic data acquired in [(11)C]PiB PET scans with five healthy volunteers and eight patients with Alzheimer\u27s disease were corrected with region-based and voxel-based partial volume corrections. Binding potential (BPND) was estimated using the two-tissue compartment model analysis with a plasma input function. Partial volume corrections significantly decreased cortical BPND values. The degree of decrease in healthy volunteers (-52.7 ± 5.8%) was larger than that in Alzheimer\u27s disease patients (-11.9 ± 4.2%). The simulation demonstrated that white matter spillover signals due to the partial volume effect resulted in an overestimation of cortical BPND, with a greater degree of overestimation for lower BPND values. Thus, an overestimation due to partial volume effects is more severe in healthy volunteers than in Alzheimer\u27s disease patients. Partial volume corrections may be useful for accurately quantifying Aβ deposition in cortical regions