Incidence and contributing factors of non-root canal treated teeth with chronic fatigue root fracture: A cross-sectional study.

BACKGROUND/PURPOSE: Chronic fatigue root fracture describes a root fracture in a non-root canal treated (non-RCT) tooth. This study aimed to report the incidence and contributing factors of non-RCT teeth with chronic fatigue root fracture in a Taiwanese population. METHODS: This cross-sectional study included teeth extracted at Taipei Veterans General Hospital in Taiwan between 2018 and 2019. The reasons for extractions were recorded and included vertical and horizontal root fractures (VRF and HRF). Comparisons of clinical factors between teeth with fatigue VRF and teeth with fatigue HRF were performed by chi-square or Fisher exact test, where appropriate. RESULTS: Of the 4207 extracted teeth examined, 263 (6.25%) had tooth fracture. Thirty-two non-RCT teeth had chronic fatigue root fracture, including 16 with VRF and 16 with HRF. The incidence was 0.76% (32/4207). The occurrence of chronic fatigue root fracture was higher in males (83.9%). The mean age of the 31 patients with chronic fatigue root fracture was 71.7 ± 13.1 years. More than half of these teeth had intact crowns with severe attrition. The fatigue VRF occurred more frequently in molars (P = 0.003), in roots with a long oval cross-section (P = 0.037), and in terminal teeth (P = 0.013) than the fatigue HRF. CONCLUSION: The incidence of chronic fatigue root fracture is 0.76%. Both VRF and HRF occur mainly in aged males, in posterior teeth with attrition, and in teeth without restoration. Tooth position, cross-section root morphology, and terminal tooth are contributing factors related to chronic fatigue root fracture.

The role of the family in health promotion: a scoping review of models and mechanisms.

The family is an important contributor to the cultural conditions that support health. Current challenges in family health promotion interventions include programme design that is not always guided by theory and change mechanisms. Multifaceted programmes also make it hard to examine what works for whom, given different family roles and the range of lifestyle behaviour and mechanisms examined within diverse conceptual frameworks and cultures. We performed a scoping review on the heterogeneous literature to map and categorize the models and mechanisms by which a family may promote health behaviours among its members. We searched five electronic databases and grey literature up to 2020. Publications were included if they examined health-promoting behaviours, influences at the family level, and outlined the behavioural mechanisms involved. Two hundred and forty studies were identified. Ecological systems theory, social cognitive theory, family systems theory and the theory of planned behaviour were the frameworks most widely used in explaining either study context and/or mechanism. The most frequently studied family mechanisms involved aspects of family support, supervision and modelling, while some studies also included individual-level mechanisms. Majority of the studies investigated parental influence on the child, while few studies assessed the elderly family member as a recipient or actor of the influences. Studies on African, Asian and Middle Eastern populations were also in the minority, highlighting room for further research. Improving the understanding of context and behavioural mechanisms for family health promotion will aid the development of public health policy and chronic disease prevention programmes, complementing efforts targeted at individuals.

The role of fibroblasts in the modulation of dental pulp inflammation.

BACKGROUND/PURPOSE: Dental pulp fibroblasts can protect dental pulp from microbial invasion. However, little is known about the interaction between pulp fibroblasts and the immune cells. In this study, the production of proinflammatory cytokines related to inflammatory cell recruitment was evaluated in tumor necrosis factor (TNF)-α-stimulated human dental pulp fibroblasts (HDPFs). The role of TNF-α-stimulated HDPFs in the cell fusion under inflammatory process was determined with the cell co-culture with peripheral blood mononuclear cells (PBMCs). METHODS: HDPFs were stimulated with various concentrations of TNF-α, and the secretion of interleukin (IL)-6, IL-8 and monocyte chemoattractant protein (MCP)-1 was analyzed by the enzyme-linked immunosorbent assay. The mRNA expression levels of intercellular adhesion molecule-1 (ICAM-1), macrophage colony-stimulating factor (M-CSF), receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) were determined by real-time quantitative polymerase chain reaction. TNF-α-treated HDPFs were co-cultured with PBMCs for 21 days, and characteristics of cell differentiation were assessed. RESULTS: TNF-α induced IL-6, IL-8 and MCP-1 production in HDPFs. Moreover, mRNA expression levels of ICAM-1, M-CSF and OPG were significantly increased in TNF-α-treated HDPFs. Co-culture of TNF-α-treated HDPFs and PBMCs stimulated formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells, and the F-actin rings were observed in these multinucleated cells. CONCLUSION: Our results indicate that under the stimulation of TNF-α, HDPFs may amplify inflammatory response by cytokines production, which in turn can modulate the differentiation of immune cells.

Evaluation of students' self-assessment performance in preclinical endodontic training by means of rubrics and a 3D printed model.

BACKGROUND/PURPOSE: Effective evaluation of students' self-assessment ability is crucial. This study was to develop a standardized 3D printed teaching model accompanied by structured scoring rubrics for preclinical endodontic training, to appraise students' self-assessment ability, and to evaluate their perceptions of the training system. METHODS: The 3D printing model was designed to house a standardized central incisor. Forty-four undergraduate dental students were enrolled and their endodontic performance was self-assessed and also rated by a teaching assistant and a tutor using 3 structured rubrics including access cavity, mechanical preparation, and obturation assessments. In total, 21 rubric evaluation items of preclinical tasks were assessed, and the assessment results from the student, teaching assistant, and tutor were compared. Furthermore, questionnaires were used to evaluate students' experiences with the new system. RESULTS: The tutor, teaching assistant, and students all had similar scorings and high intraclass correlation coefficients (ICC) for mechanical preparation and obturation rubrics, while the students had underestimated scores on the access cavity rubric with a rather low ICC of 0.387, which also lead to the underestimated overall scoring (P < 0.05). Among the 21 evaluation criteria, 9 items were rated statistically different (P < 0.05), which denoted the major deficiencies of students' self-assessments. More than 80% of students rated satisfied for most of the questions regarding the new training system, except the tactile sensation, hardness, and radiopacity. CONCLUSION: The proposed standardized 3D printed model and structured scoring rubrics is feasible for preclinical endodontic training, and standardized evaluation of students' self-assessment ability.

Successful treatment of vertical root fracture through intentional replantation and root fragment bonding with 4-META/MMA-TBB resin.

BACKGROUND/PURPOSE: Vertical root fracture (VRF) is a complication in endodontically treated teeth. This study aimed to assess the clinical outcomes of treatment of 6 VRF teeth with intentional replantation and root fragment bonding with 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin. METHODS: A series of 6 complete VRF teeth (one incisor, one canine, one premolar, and 3 M) were treated through intentional replantation and root fragment bonding with 4-META/MMA-TBB resin. RESULTS: This study included 6 VRF teeth in 6 patients (one man and 5 women; mean age, 44 ± 8 years). All 6 teeth had VRF in the bucco-lingual direction and one tooth had concomitant VRF in the mesio-distal direction. The root thickness was classified as thick in all 6 teeth. Of the 6 VRF teeth, 4 had biting, percussion, or palpation pain, 4 had gingival swelling, 3 had sinus tracts, 3 had discomfort, and one had tooth mobility. Radiographically, 5 of the 6 teeth had periradicular radiolucent lesions, 4 of which exhibited complete regression and one of which exhibited nearly complete regression after root fragment bonding therapy. Because all 6 treated teeth exhibited sound function in the oral cavity after a follow-up period ranging from 33 to 74 (mean, 50 ± 15) months, the clinical outcomes were all considered to be successful. CONCLUSION: For a VRF tooth, in addition to tooth extraction, intentional replantation combined with root fragment bonding with 4-META/MMA-TBB resin is a successful treatment modality that can be used to preserve a complete VRF tooth.

Long-term reproducibility of GABA magnetic resonance spectroscopy.

Recent findings suggest that cortical gamma aminobutyric acid (GABA) levels may provide a surrogate marker for a number of psychiatric and neurological conditions, as well as behavioural traits. However, the natural variability of GABA levels in the human brain over long periods of time (>8 days) has not yet been studied. The purpose of this work was to investigate the long-term variability of GABA concentrations in the human occipital cortex. Nineteen healthy male participants were recruited and underwent two sessions of magnetic resonance spectroscopy (MRS) to determine occipital GABA levels with an average between-session interval of 7 months. We assessed between-session variability, as well as the correlation between session 1 and session 2 GABA measurements. The mean coefficient of variation between sessions was 4.3% (bootstrap 95% confidence interval: 2.5, 6.4), which is comparable to reported GABA variability measurements over much shorter time intervals (<8 days). A significant positive correlation was observed between session 1 and session 2 GABA measurements (r=0.53, p=0.014), and the intra-class correlation coefficient was calculated to be 0.52 which was also statistically significant (p=0.012). These findings establish experimentally that GABA concentrations in the occipital cortex, as measured by MRS, are relatively stable over periods as long as 7 months. The findings have significant implications for the internal validity of longitudinal studies of GABA levels in the human brain, and they lend foundational support to studies relating GABA levels to behavioural traits in healthy individuals.

Short-Wavelength Infrared Imaging of Infected and Affected Dentin.

Stains produced by bacteria or those found in blood and food byproducts accumulate in highly porous caries lesions. They can interfere with accurate diagnosis and the selective removal of carious tissue during cavity preparations. Short-wavelength infrared (SWIR) imaging studies have shown that stain molecules do not absorb light beyond 1200 nm. The objective of this study was to image affected and infected dentin atSWIR wavelengths. Sections of 3 mm thickness were cut from the extracted teeth with deep dentinal lesions. The sound (normal), affected (stained), and infected (demineralized) dentin on each section were examined with reflected light at wavelengths from 400 to 1700 nm, red and green fluorescence, and with optical coherence tomography (OCT). Microcomputed tomography (microCT) was used to measure the mineral density at each location investigated. Significant (p < 0.05) differences were observed in the reflected light intensity at 400-850 nm and for fluorescence between the sound, affected, and infected dentin. SWIR imaging did not show significant reductions in reflectivity for the affected and infected dentin. SWIR images may be valuable for monitoring the lateral spread of dentinal lesions on the occlusal surfaces of teeth.

A NO way to BOLD? Dietary nitrate alters the hemodynamic response to visual stimulation.

Neurovascular coupling links neuronal activity to vasodilation. Nitric oxide (NO) is a potent vasodilator, and in neurovascular coupling NO production from NO synthases plays an important role. However, another pathway for NO production also exists, namely the nitrate-nitrite-NO pathway. On this basis, we hypothesized that dietary nitrate (NO3-) could influence the brain's hemodynamic response to neuronal stimulation. In the present study, 20 healthy male participants were given either sodium nitrate (NaNO3) or sodium chloride (NaCl) (saline placebo) in a crossover study and were shown visual stimuli based on the retinotopic characteristics of the visual cortex. Our primary measure of the hemodynamic response was the blood oxygenation level dependent (BOLD) response measured with high-resolution functional magnetic resonance imaging (0.64×0.64×1.8 mm) in the visual cortex. From this response, we made a direct estimate of key parameters characterizing the shape of the BOLD response (i.e. lag and amplitude). During elevated nitrate intake, corresponding to the nitrate content of a large plate of salad, both the hemodynamic lag and the BOLD amplitude decreased significantly (7.0±2% and 7.9±4%, respectively), and the variation across activated voxels of both measures decreased (12.3±4% and 15.3±7%, respectively). The baseline cerebral blood flow was not affected by nitrate. Our experiments demonstrate, for the first time, that dietary nitrate may modulate the local cerebral hemodynamic response to stimuli. A faster and smaller BOLD response, with less variation across local cortex, is consistent with an enhanced hemodynamic coupling during elevated nitrate intake. These findings suggest that dietary patterns, via the nitrate-nitrite-NO pathway, may be a potential way to affect key properties of neurovascular coupling. This could have major clinical implications, which remain to be explored.

Dental optical coherence tomography.

This review paper describes the applications of dental optical coherence tomography (OCT) in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

Diagnostic Performance of Multispectral SWIR Transillumination and Reflectance Imaging for Caries Detection.

The aim of this clinical study was to compare the diagnostic performance of dual short wavelength infrared (SWIR) occlusal transillumination and reflectance multispectral imaging with conventional visual assessment and radiography for caries detection on premolars scheduled for extraction for orthodontics reasons. Polarized light microscopy (PLM) and micro-computed tomography (microCT) performed after tooth extraction were used as gold standards. The custom-fabricated imaging probe was 3D-printed and the imaging system employed a SWIR camera and fiber-optic light sources emitting light at 1300 nm for occlusal transillumination and 1600 nm for reflectance measurements. Teeth (n = 135) on 40 test subjects were imaged in vivo using the SWIR imaging prototype in the study and teeth were extracted after imaging. Our study demonstrates for the first time that near-simultaneous real-time transillumination and reflectance video can be successfully acquired for caries detection. Both SWIR imaging modalities had markedly higher sensitivity for lesions on proximal and occlusal surfaces compared to conventional methods (visual and radiographic). Reflectance imaging at 1600 nm had higher sensitivity and specificity than transillumination at 1300 nm. The combined SWIR methods yielded higher specificity but the combined sensitivity was lower than for each individual method.

Time-resolved SWIR imaging for the assessment of the activity of occlusal caries lesions.

The aim of this study was to develop a clinical SWIR reflectance handpiece to assess the activity of lesions on the occlusal surfaces. The time-resolved reflectivity of 10 active and 10 arrested occlusal caries lesions on extracted teeth was monitored at 1470 nm using a benchtop system and a modified clinical prototype during forced air drying. The presence of a highly mineralized surface layer measured with microcomputed tomography (microCT) was used to indicate lesion activity. Multiple kinetic parameters were extracted from the acquired SWIR time versus intensity dehydration curves and used to assess lesion activity. Three parameters: delay, %Ifin , and rate calculated from the SWIR dehydration curves were significantly different (p < 0.05) between active and arrested lesions. The modified clinical probe was able to completely dehydrate all the active lesion areas in the occlusal pits and fissures in less than 30 s.

Gray matter nulled and vascular space occupancy dependent fMRI response to visual stimulation during hypoxic hypoxia.

Two cerebral blood volume (CBV)-weighted fMRI techniques, gray matter nulled (GMN) and vascular space occupancy (VASO)-dependent techniques at spatial resolution of 2 × 2 × 5 mm(3), were compared in the study investigating functional responses in the human visual cortex to stimulation in normoxia (inspired O(2) = 21%) and mild hypoxic hypoxia (inspired O(2) = 12%). GMN and VASO signals and T(2)* were quantified in activated voxels. While the CBV-weighted signal changes in voxels activated by visual stimulation were similar in amplitude in both fMRI techniques in both oxygenation conditions, the number of activated voxels during hypoxic hypoxia was significantly reduced by 72 ± 22% in GMN fMRI and 66 ± 23% in VASO fMRI. T(2)* prolonged in GMN and VASO activated voxels in normoxia by 1.6 ± 0.5 ms and 1.7 ± 0.5 ms, respectively. In hypoxia, however, T(2)* shortened in GMN-activated voxels by 0.7 ± 0.6 ms (p < 0.001 relative to normoxia), but prolonged in VASO-activated ones by 1.1 ± 0.6 ms (p < 0.05 relative to normoxia). The data show that the hemodynamic responses to visual stimulation were not affected by hypoxic hypoxia, but T(2)* increases by both CBV-weighted fMRI techniques were smaller in activated voxels in hypoxia. The mechanisms influencing GMN fMRI signal in both oxygenation conditions were explored by simulating effects of the oxygen extraction fraction (OEF) and partial voluming with cerebral spinal fluid (CSF) and white matter in imaging voxels. It is concluded that while GMN fMRI data point to increased, rather than decreased OEF during visual stimulation in hypoxia, partial voluming by CSF is likely to affect the CBV quantification by GMN fMRI under the experimental conditions used.

Degree of polarization uniformity for dental calculus visualization.

During the treatment for periodontitis, the removal of dental calculus is essential. Previously, we have proposed the DAM algorithm for intuitive identification of the site of lesion, enabling the non-contact assessment during the operation. Nonetheless, the delineation of dental calculus was still imperfect. To this end, here we utilized the power of polarization-sensitive optical coherence tomography and evaluated the contrast called degree of polarization uniformity for dental calculus visualization. The result showed that the selected index demonstrated excellent contrast of dental calculus from other normal dental hard tissues. The proposed contrast is promising for accurate dental calculus delineation.

Family Resilience and Psychological Responses to COVID-19: A Study of Concordance and Dyadic Effects in Singapore Households.

The impacts of COVID-19 may be magnified in a shared environment like the household, especially with people spending extended time at home during the pandemic. Family resilience is the ability of a family to adapt to crisis and can be a protective factor against stress and negative affect. While there have been calls to address family resilience during the pandemic, there is a lack of empirical study on its benefit. In this dyadic observational study, we sought to investigate the concordance of family members' psychological responses to COVID-19, whether dyad members' risk factors (COVID-19 exposure and financial impact) mutually affected each other's psychological responses, and importantly, whether family resilience was a significant factor in these responses. A total of 200 family dyads from the same household completed the Family Resilience Assessment Scale and questionnaires on COVID-19 threat perception, impacts, and exposure. We found concordant dyad responses for COVID-19 threat perception, but not for psychological impact. Using the Actor-Partner-Interdependence Model framework, we found that one's psychological impact was affected by the financial impact from both dyad members. After controlling for risk factors and demographic covariates, we found that family resilience significantly associated with lower COVID-19 psychological impact, though not with threat perception. The findings suggest that both family and individual factors need to be addressed and there may be benefit in addressing multilevel risk and protective factors using an ecological systems approach, which may help prepare the population for future crises.

The validation of culturally appropriate scales to assess the family health climate in a multi-ethnic Asian population.

Background: The Family Health Climate (FHC) is a family environment attribute postulated to influence the health behaviors of family members. It can be measured by domain scales for physical activity (FHC-PA) and nutrition (FHC-NU), which have been validated and used to identify health climate patterns in families in Western populations. To extend the use of the scales to Asian settings, this study aimed to adapt and validate the instruments for use in the multi-ethnic population of Singapore, accounting for language and cultural differences. Methods: In Part A (n = 40) to adapt the scales for the Singapore population, we performed cognitive interviews, face validity testing and pre-testing of the instruments (n = 40). Besides English, the scales were translated into Chinese and Malay. In Part B (n = 400), we performed exploratory and confirmatory factor analyses respectively on two random samples. We also tested for item discriminant validity, internal consistency reliability, construct validity, and measurement invariance. Results: The findings from the cognitive interviews in Part A led to scale adaptations to accommodate cultural and linguistic factors. In Part B, EFA on Sample I resulted in a three-factor model for the PA scale (accounting for 71.2% variance) and a four-factor model for the NU scale (accounting for 72.8% variance). CFA on Sample II indicated acceptable model fits: FHC-PA: χ2 = 192.29, df = 101, p < 0.001, χ2/df = 1.90; SRMR = 0.049; RMSEA = 0.067; CFI = 0.969; TLI = 0.963; FHC-NU: χ2 = 170.46, df = 98, p < 0.001, χ2/df = 1.74; SRMR = 0.036; RMSEA = 0.061; CFI = 0.967; TLI = 0.960. The scores of family members demonstrated significant agreement on the FHC-PA (Sg) [ICC(2, 2) = 0.77] and FHC-NU (Sg) [ICC(2, 2) = 0.75] scales. Findings suggest good evidence for item discriminant validity, internal consistency reliability, construct validity, and measurement invariance. Short versions of the scales were also developed. Conclusion: We adapted, translated and validated the scales for assessing the health climate of families in Singapore, including the development of short versions. The results showed good psychometric properties and the constructs had significant relationships with health behaviors and routines. Improving our understanding of family influences on individual health behavior will be important in developing multi-level strategies for health promotion and chronic disease prevention.

The preventability of trauma-related death: A two-year cohort study in a trauma center in middle Taiwan.

INTRODUCTION: The preventable death rate (PDR) is an important parameter in the quality assurance of traumatic care. Medical errors or untimely management may occur during stressful trauma care, resulting in preventable deaths. We aimed to develop an applicable PDR model in a trauma center in middle Taiwan. MATERIALS AND METHODS: We identified adult trauma-related deaths which occurred from January 1, 2018 to December 31, 2019 at our hospital. Patients with a trauma and injury severity score (TRISS) <75% or ≥75% but with a chance of preventability, as determined by a trauma surgeon, were discussed by a panel comprising an emergency physician and surgeons specializing in different fields of medicine. Deaths were subsequently classified as definitely preventable (DP), potentially preventable (PP), or non-preventable (NP). Causes of DP or PP deaths were categorized as delayed diagnosis, delayed treatment, technical error, or inadequate infection prevention/control. The relationship between the time and cause of preventable deaths was also analyzed. RESULTS: This study included 127 trauma-related deaths, of which 39 were discussed by the panel. Eight patients (6.3%) were categorized as DP, eight (6.3%) as PP, and 111 (87.4%) as NP. Among patients with preventable deaths, inadequate infection prevention/control, delayed treatment, delayed diagnosis, and technical error were identified in six (37.5%), five (31.2%), three (18.8%), and two (12.5%) patients, respectively. Four patients in the inadequate infection prevention/control group (4/6, 66.7%) died of aspiration pneumonia during the recovery phase. CONCLUSION: A PDR evaluation model was developed and revealed that postoperative care is as important as a timely diagnosis and treatment to avoid preventable deaths following trauma.

Development of digital shade guides for color assessment using a digital camera with ring flashes.

Digital photographs taken with cameras and ring flashes are commonly used for dental documentation. We hypothesized that different illuminants and camera's white balance setups shall influence color rendering of digital images and affect the effectiveness of color matching using digital images. Fifteen ceramic disks of different shades were fabricated and photographed with a digital camera in both automatic white balance (AWB) and custom white balance (CWB) under either light-emitting diode (LED) or electronic ring flash. The Commission Internationale d'Éclairage L*a*b* parameters of the captured images were derived from Photoshop software and served as digital shade guides. We found significantly high correlation coefficients (r² > 0.96) between the respective spectrophotometer standards and those shade guides generated in CWB setups. Moreover, the accuracy of color matching of another set of ceramic disks using digital shade guides, which was verified by ten operators, improved from 67% in AWB to 93% in CWB under LED illuminants. Probably, because of the inconsistent performance of the flashlight and specular reflection, the digital images captured under electronic ring flash in both white balance setups revealed less reliable and relative low-matching ability. In conclusion, the reliability of color matching with digital images is much influenced by the illuminants and camera's white balance setups, while digital shade guides derived under LED illuminants with CWB demonstrate applicable potential in the fields of color assessments.

Towards a Parsimonious Pathway Model of Modifiable and Mediating Risk Factors Leading to Diabetes Risk.

Modifiable risk factors are of interest for chronic disease prevention. Few studies have assessed the system of modifiable and mediating pathways leading to diabetes mellitus. We aimed to develop a pathway model for Diabetes Risk with modifiable Lifestyle Risk factors as the start point and Physiological Load as the mediator. As there are no standardised risk thresholds for lifestyle behaviour, we derived a weighted composite for Lifestyle Risk. Physiological Load was based on an index using clinical thresholds. Sociodemographics are non-modifiable risk factors and were specified as covariates. We used structural equation modeling to test the model, first using 2014/2015 data from the Indonesian Family Life Survey. Next, we fitted a smaller model with longitudinal data (2007/2008 to 2014/2015), given limited earlier data. Both models showed the indirect effects of Lifestyle Risk on Diabetes Risk via the mediator of Physiological Load, whereas the direct effect was only supported in the cross-sectional analysis. Specifying Lifestyle Risk as an observable, composite variable incorporates the cumulative effect of risk behaviour and differentiates this study from previous studies assessing it as a latent construct. The parsimonious model groups the multifarious risk factors and illustrates modifiable pathways that could be applied in chronic disease prevention efforts.

Measuring arterial and tissue responses to functional challenges using arterial spin labeling.

The measurement of cerebral blood flow (CBF) in functional MRI studies that aim for non-invasive, quantitative and reliable measurements is a challenge. Here, we tested the feasibility of a recently developed, model-free CBF technique to study vascular dynamics upon functional challenges. Multiple inversion time-point signals were measured from arterial and tissue compartments, allowing for the calculation of CBF through a process of deconvolution. Using graded visual stimulation known to produce increasing hemodynamic responses, we recorded significant and graded DeltaCBF and Deltatau(m) (microvascular arrival time change) that were highly comparable to those estimated by a standard 3-parameter fit based on the general kinetic model, though the absolute values had weaker agreement. Estimated arterial blood volumes (excluding substantial arteriolar contribution) did not show significant change with visual stimulation. Bolus arrival times in the microvascular compartment shortened more as compared to the arrival times from the arterial compartment during visual stimulation, suggesting larger involvement of the microvasculature in local neuronal response. While there are limitations, the model-free analysis method has the potential to offer useful vascular information in fMRI studies.