Short-term treatment with hepatoselective NO donor V-PYRRO/NO improves blood flow in hepatic microcirculation in liver steatosis in mice

BACKGROUND

The impairment of liver sinusoidal endothelial cells (LSECs) function and diminished nitric oxide (NO) production has been regarded as an important pathogenic factor in liver steatosis. Restoring NO-dependent function was shown to counteract liver steatosis, obesity, and insulin resistance. However, it is not known whether restored liver perfusion and improvement in hepatic blood flow contributes to the anti-steatotic effects of NO. Taking advantage of in vivo MRI, we have examined the effects of short-term treatment with the hepatoselective NO donor V-PYRRO/NO on hepatic microcirculation in advanced liver steatosis.

METHODS

Male C57BL/6 mice fed for six months a high fat diet (HFD; 60 kcal% of fat) were treated for 3 weeks with V-PYRRO/NO (twice a day 5mg/kg b.w. ip). An MRI assessment of liver perfusion using the FAIR-EPI method and a portal vein blood flow using the FLASH method were performed. Blood biochemistry, glucose tolerance tests, a histological evaluation of the liver, and liver NO concentrations were also examined.

RESULTS

Short-term treatment with V-PYRRO/NO releasing NO selectively in the liver improved liver perfusion and portal vein blood flow. This effect was associated with a slight improvement in glucose tolerance but there was no effect on liver steatosis, body weight, white adipose tissue mass, plasma lipid profile, or aminotransferase activity.

CONCLUSION

Short-term treatment with V-PYRRO/NO-derived NO improves perfusion in hepatic microcirculation and this effect may also contribute to the anti-steatotic effects of hepatoselective NO donors linked previously to the modulation of glucose and lipid metabolism in the liver.

Activation pattern of ACE2/Ang-(1-7) and ACE/Ang II pathway in course of heart failure assessed by multiparametric MRI in vivo in Tgαq*44 mice

Here, we analyzed systemic (plasma) and local (heart/aorta) changes in ACE/ACE-2 balance in Tgαq*44 mice in course of heart failure (HF). Tgαq*44 mice with cardiomyocyte-specific Gαq overexpression and late onset of HF were analyzed at different age for angiotensin pattern in plasma, heart, and aorta using liquid chromatography/mass spectrometry, for progression of HF by in vivo magnetic resonance imaging under isoflurane anesthesia, and for physical activity by voluntary wheel running. Six-month-old Tgαq*44 mice displayed decreased ventricle radial strains and impaired left atrial function. At 8-10 mo, Tgαq*44 mice showed impaired systolic performance and reduced voluntary wheel running but exhibited preserved inotropic reserve. At 12 mo, Tgαq*44 mice demonstrated a severe impairment of basal cardiac performance and modestly compromised inotropic reserve with reduced voluntary wheel running. Angiotensin analysis in plasma revealed an increase in concentration of angiotensin-(1-7) in 6- to 10-mo-old Tgαq*44 mice. However, in 12- to 14-mo-old Tgαq*44 mice, increased angiotensin II was noted with a concomitant increase in Ang III, Ang IV, angiotensin A, and angiotensin-(1-10). The pattern of changes in the heart and aorta was also compatible with activation of ACE2, followed by activation of the ACE pathway. In conclusion, mice with cardiomyocyte Gαq protein overexpression develop HF that is associated with activation of the systemic and the local ACE/Ang II pathway. However, it is counterbalanced by a prominent ACE2/Ang-(1-7) activation, possibly allowing to delay decompensation. NEW & NOTEWORTHY Changes in ACE/ACE-2 balance were analyzed based on measurements of a panel of nine angiotensins in plasma, heart, and aorta of Tgαq*44 mice in relation to progression of heart failure (HF) characterized by multiparametric MRI and exercise performance. The early stage of HF was associated with upregulation of the ACE2/angiotensin-(1-7) pathway, whereas the end-stage HF was associated with downregulation of ACE2/angiotensin-(1-7) and upregulation of the ACE/Ang II pathway. ACE/ACE-2 balance seems to determine the decompensation of HF in this model.

Uptake and bioreactivity of charged chitosan-coated superparamagnetic nanoparticles as promising contrast agents for magnetic resonance imaging

Bioreactivity of superparamagnetic iron oxide nanoparticles (SPION) coated with thin layers of either cationic or anionic chitosan derivatives and serving as contrast agents in magnetic resonance imaging (MRI) was studied in vivo using BALB/c mouse model. Synthesized dual-modal fluorescing SPION were tracked in time using both fluorescent imaging and MRI. Although SPION started to be excreted by kidneys relatively shortly after administration they were uptaken by liver enhancing MRI contrast even up to 7 days. Importantly, chitosan-coated SPION caused only mild activation of acute phase response not affecting biochemical parameters of blood. Liver histology indicated the presence of SPION and modest increase in the number of Kupffer cells. The overall results indicated that SPION coated with ultrathin layers of chitosan ionic derivatives can serve as T₂ contrast agents for diagnosis of liver diseases or imaging of other organs assuming the dose is optimized according to the need.

Exercise training in Tgαq*44 mice during the progression of chronic heart failure: cardiac vs. peripheral (soleus muscle) impairments to oxidative metabolism

Cardiac function, skeletal (soleus) muscle oxidative metabolism, and the effects of exercise training were evaluated in a transgenic murine model (Tgα_q*44) of chronic heart failure during the critical period between the occurrence of an impairment of cardiac function and the stage at which overt cardiac failure ensues (i.e., from 10 to 12 mo of age). Forty-eight Tgα_q*44 mice and 43 wild-type FVB controls were randomly assigned to control groups and to groups undergoing 2 mo of intense exercise training (spontaneous running on an instrumented wheel). In mice evaluated at the beginning and at the end of training we determined: exercise performance (mean distance covered daily on the wheel); cardiac function in vivo (by magnetic resonance imaging); soleus mitochondrial respiration ex vivo (by high-resolution respirometry); muscle phenotype [myosin heavy chain (MHC) isoform content; citrate synthase (CS) activity]; and variables related to the energy status of muscle fibers [ratio of phosphorylated 5'-AMP-activated protein kinase (AMPK) to unphosphorylated AMPK] and mitochondrial biogenesis and function [peroxisome proliferative-activated receptor-γ coactivator-α (PGC-1α)]. In the untrained Tgα_q*44 mice functional impairments of exercise performance, cardiac function, and soleus muscle mitochondrial respiration were observed. The impairment of mitochondrial respiration was related to the function of complex I of the respiratory chain, and it was not associated with differences in CS activity, MHC isoforms, p-AMPK/AMPK, and PGC-1α levels. Exercise training improved exercise performance and cardiac function, but it did not affect mitochondrial respiration, even in the presence of an increased percentage of type 1 MHC isoforms. Factors "upstream" of mitochondria were likely mainly responsible for the improved exercise performance.NEW & NOTEWORTHY Functional impairments in exercise performance, cardiac function, and soleus muscle mitochondrial respiration were observed in transgenic chronic heart failure mice, evaluated in the critical period between the occurrence of an impairment of cardiac function and the terminal stage of the disease. Exercise training improved exercise performance and cardiac function, but it did not affect the impaired mitochondrial respiration. Factors "upstream" of mitochondria, including an enhanced cardiovascular O₂ delivery, were mainly responsible for the functional improvement.

Activation of the nicotinamide N-methyltransferase (NNMT)-1-methylnicotinamide (MNA) pathway in pulmonary hypertension

Background

Pulmonary arterial hypertension (PAH) is associated with inflammatory response but it is unknown whether it is associated with alterations in NNMT activity and MNA plasma concentration. Here we examined changes in NNMT-MNA pathway in PAH in rats and humans.

Methods

PAH in rats was induced by a single subcutaneous injection of MCT (60 mg/kg). Changes in NNMT activity in the lungs and liver (assessed as the rate of conversion of nicotinamide (NA) to MNA), changes in plasma concentration of MNA and its metabolites (analyzed by LC/MS) were analyzed in relation to PAH progression. PAH was characterized by right ventricular hypertrophy (gross morphology), cardiac dysfunction (by MRI), lung histopathology, lung ultrastructure, and ET-1 concentration in plasma. NO-dependent and PGI₂-dependent function in isolated lungs was analyzed. In naive patients with idiopathic pulmonary hypertension (IPAH) characterized by hemodynamic and biochemical parameters MNA and its metabolites in plasma were also measured.

Results

MCT-injected rats developed hypertrophy and functional impairment of the right ventricle, hypertrophy of the pulmonary arteries, endothelial ultrastructural defects and a progressive increase in ET-1 plasma concentration—findings all consistent with PAH development. In isolated lung, NO-dependent regulation of hypoxic pulmonary vasoconstriction was impaired, while PGI₂ production (6-keto-PGF_1α) was increased. NNMT activity increased progressively in the liver and in the lungs following MCT injection, and NNMT response was associated with an increase in MNA and 6-keto-PGF_1α concentration in plasma. In IPAH patients plasma concentration of MNA was elevated as compared with healthy controls.

Conclusions

Progression of pulmonary hypertension is associated with the activation of the NNMT-MNA pathway in rats and humans. Given the vasoprotective activity of exogenous MNA, which was previously ascribed to PGI₂ release, the activation of the endogenous NNMT-MNA pathway may play a compensatory role in PAH.

Retrospectively gated MRI for in vivo assessment of endothelium-dependent vasodilatation and endothelial permeability in murine models of endothelial dysfunction

Endothelial dysfunction is linked to impaired endothelial-dependent vasodilatation and permeability changes. Here, we quantify both of these phenomena associated with endothelial dysfunction by MRI in vivo in mice. Endothelial function was evaluated in the brachiocephalic artery (BCA) and left carotid artery (LCA) in ApoE/LDLR(-/-) and high-fat diet (HFD)-fed mice as compared with control mice (C57BL/6J). The 3D IntraGate® FLASH sequence was used for evaluation of changes in vessels' cross-sectional area (CSA) and volume following acetylcholine (Ach) administration. Evaluation of endothelial permeability after administration of contrast agent (Galbumin, BioPAL) was based on the variable flip angle method for the assessment of parameters based on the relaxation time (T1 ) value. In order to confirm the involvement of nitric oxide (NO) in response to Ach, L-NAME-treated mice were also analyzed. To confirm that endothelial permeability changes accompany the impairment of Ach-dependent vasodilatation, permeability changes were analyzed in isolated, perfused carotid artery. In C57BL/6J mice, Ach-induced vasodilatation led to an approximately 25% increase in CSA in both vessels, which was temporarily dissociated from the effect of Ach on heart rate. In ApoE/LDLR(-/-) or HFD-fed mice Ach induced a paradoxical vasoconstriction that amounted to approximately 30% and 50% decreases in CSA of BCA and LCA respectively. In ApoE/LDLR(-/-) and HFD-fed mice endothelial permeability in BCA was also increased (fall in T1 by about 25%). In L-NAME-treated mice Ach-induced vasodilatation in BCA was lost. In isolated, perfused artery from ApoE/LDLR(-/-) mice endothelial permeability was increased. MRI-based assessment of endothelium-dependent vasodilatation induced by Ach and endothelial permeability using a retrospectively self-gated 3D gradient-echo sequence (IntraGate® FLASH) enables the reliable detection of systemic endothelial dysfunction in mice and provides an important tool for the experimental pharmacology of the endothelium in murine models of diseases in vivo. Copyright © 2016 John Wiley & Sons, Ltd.

Novel nanostructural contrast for magnetic resonance imaging of endothelial inflammation: targeting SPIONs to vascular endothelium

This study aimed to develop superparamagnetic iron oxide nanoparticles (SPIONs) targeted to the areas of vascular endothelium changed in the initial inflammation process, a first step of numerous cardiovascular diseases.

Stable polymersomes based on ionic–zwitterionic block copolymers modified with superparamagnetic iron oxide nanoparticles for biomedical applications

Novel biocompatible polymersomes with semipermeable ionic membranes were used as promising delivery systems.

The effect of the renin-angiotensin-aldosterone system inhibition on myocardial function in early and late phases of dilated cardiomyopathy in Tgaq*44 mice

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS) determines progression of heart failure (HF) in humans, and RAAS inhibition is a major therapeutic strategy in HF.

AIM

To assess the effect of angiotensin-converting enzyme inhibitor (ACE-I) and aldosterone receptor antagonist (ARA) therapy on the development of HF at its early and late stage in a murine model of dilated cardiomyopathy (Tgaq*44 mice).

METHODS

Tgaq*44 mice at the early or advanced stage of HF received combined therapy including ACE-I (perindopril 2 mg/kg) and ARA (canrenone 20 mg/kg). Cardiac function was assessed by magnetic resonance imaging before and after 2 months of treatment.

RESULTS

Combined therapy with perindopril and canrenone resulted in preserved systolic function at the early stage and reduced chamber dilatation at the advanced stage of HF in Tgaq*44 mice.

CONCLUSIONS

Activation of the RAAS is involved in progression of HF in Tgaq*44 mice with dilated cardiomyopathy. Therapeutic efficacy of ACE-I and ARA to inhibit systolic dysfunction and cardiac chamber dilation depends on the stage of HF development.

Heart function in magnetic resonance imaging and the mesenteric artery reactivity in rats receiving lead-contaminated drinking water

The aim of this study was to evaluate the effect of lead (Pb)-contaminated drinking water on magnetic resonance imaging (MRI)-estimated cardiac function, vascular reactivity, and serum lipids in rats. For 3 months, male Wistar rats, aged 4–6 weeks, were given drinking water with the addition of lead acetate at a concentration of 100 ppm Pb (10 rats) or water free from Pb (8 control rats). The cardiac MRI was performed at rest and under β-adrenergic stimulation on a 4.7 T scanner using electrocardiogram-triggered gradient echo (FLASH) cine sequence. After 1–2 weeks of the MRI test, experiments were performed ex vivo. After stabilization of perfusion pressure (PP), norepinephrine at doses from 0.01 to 5.0 μg was dissolved in Krebs solution, injected in a volume of 100 μl, and next infused at a concentration of 0.5 μg/ml into the isolated mesenteric artery. In this manner, preconstricted mesenteric bed was used to determine PP changes induced by acetylcholine, given at doses from 0.05 to 5.0 μg, before and during the infusion of nitric oxide synthase inhibitor (1.0 μg/ml). At the end, dobutamine (5 mg), followed by potassium chloride (10.5 mg), was injected. Lipid levels were determined enzymatically, blood Pb level was measured by the atomic absorption spectrophotometer. This study showed that Pb impairs the left ventricular systolic and diastolic function. Pb-induced changes in response to resistance of vessels to vasoactive agents may be secondary to the reduced left ventricular ejection fraction. The high-density lipoprotein subfraction 2 (HDL2) is involved in the cardiovascular effect of Pb.

Stable aqueous dispersion of superparamagnetic iron oxide nanoparticles protected by charged chitosan derivatives

This article presents the synthesis and characterization of biocompatible superparamagnetic iron oxide nanoparticles (SPIONs) coated with ultrathin layer of anionic derivative of chitosan. The water-based fabrication involved a two-step procedure. In the first step, the nanoparticles were obtained by co-precipitation of ferrous and ferric aqueous salt solutions with ammonia in the presence of cationic derivative of chitosan. In the second step, such prepared materials were subjected to adsorption of oppositely charged chitosan derivative which resulted in the preparation of negatively charged SPIONs. They were found to develop highly stable dispersion in water. The core size of the nanocoated SPIONs, determined using transmission electron microscopy, was measured to be slightly above 10 nm. The coated nanoparticles form aggregates with majority of them having hydrodynamic diameter below 100 nm, as measured by dynamic light scattering. Their composition and properties were studied using FTIR and thermogravimetric analyses. They exhibit magnetic properties typical for superparamagnetic material with a high saturation magnetization value of 123 ± 12 emu g(-1) Fe. Very high value of the measured r(2) relaxivity, 369 ± 3 mM(-1) s(-1), is conducive for the potential application of the obtained SPIONs as promising contrast agents in magnetic resonance imaging. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11051-012-1372-9) contains supplementary material, which is available to authorized users.

Preserved cardiomyocyte function and altered desmin pattern in transgenic mouse model of dilated cardiomyopathy

Taking advantage of the unique model of slowly developing dilated cardiomyopathy in mice with cardiomyocyte-specific transgenic overexpression of activated Gαq protein (Tgαq*44 mice) we analyzed the contribution of the cardiomyocyte malfunction, fibrosis and cytoskeleton remodeling to the development of heart failure in this model. Left ventricular (LV) in vivo function, myocardial fibrosis, cytoskeletal proteins expression and distribution, Ca(2+) handling and contractile function of isolated cardiomyocytes were evaluated at the stages of the early, compensated, and late, decompensated heart failure in 4-, 12- and 14-month-old Tgαq*44 mice, respectively, and compared to age-matched wild-type FVB mice. In the 4-month-old Tgαq*44 mice significant myocardial fibrosis, moderate myocyte hypertrophy and increased expression of regularly arranged and homogenously distributed desmin accompanied by increased phosphorylation of desmin chaperone protein, αB-crystallin, were found. Cardiomyocyte shortening, Ca(2+) handling and LV function were not altered. At 12 and 14 months of age, Tgαq*44 mice displayed progressive deterioration of the LV function. The contractile performance of isolated myocytes was still preserved, and the amplitude of Ca(2+) transients was even increased probably due to impairment of Na(+)/Ca(2+) exchanger function, while fibrosis was more extensive than in younger mice. Moreover, substantial disarrangement of desmin distribution accompanied by decreasing phosphorylation of αB-crystallin appeared. In Tgαq*44 mice disarrangement of desmin, at least partly related to inadequate phosphorylation of αB-crystallin seems to be importantly involved in the progressive deterioration of contractile heart function.

Application of magnetic resonance imaging in vivo for the assessment of the progression of systolic and diastolic dysfunction in a mouse model of dilated cardiomyopathy

BACKGROUND

The impairment of cardiac diastolic function is essential for the development and progression of heart failure, regardless of the systolic performance of the heart. Novel methods of diagnosis of diastolic dysfunction in experimental animals are needed in order to validate the effectiveness of novel heart failure treatment.

AIM

The in vivo characterisation of diastolic and systolic function of the heart during heart failure progression in Tgalphaq*44 mice using magnetic resonance imaging (MRI) and original image analysis.

METHODS

Cardiac function in vivo in both Tgalphaq*44 and FVB mice was analysed using MRI at 4.7 T. Magnetic resonance imaging was performed using an ECG triggered fast gradient echo (cine-like flow compensated FLASH) sequence. For the assessment of left ventricle (LV) dynamics at least 20 images per cardiac cycle were acquired in the midventricular short-axis projection at the level of papillary muscles. End-systolic (ESA) and end-diastolic (EDA) areas were estimated from the minimum and maximum values found in the area-time plot. Fractional area change (FAC) defined as (EDA-ESA)/EDA, ejection (ER) and filling (FR) rates defined as slope of the beginning part of the systolic and diastolic limbs were calculated. In addition, heart failure progression in Tgalphaq*44 mice was assessed by morphometric parameters (ventricular weight to body weight index and wet to dry lung weight index), level of BNP mRNA expression as well as survival.

RESULTS

Systolic function assessed by FAC% and ER was stable but slightly impaired up to 10 months of age in Tgalphaq*44 mice as compared to the FVB mice. After 12 months of age of the Tgalphaq*44 mice there was a progressive deterioration of systolic function (ER at 10, 12, 14 months of age were 0.0188 +/- 0.00434, 0.0140 +/- 0.00474, 0.0115 +/- 0.00469 1/ms, respectively). Diastolic function of the Tgalphaq*44 hearts was preserved or even slightly augmented between 4 and 10 months of age, then at the age of 12 months and later profoundly impaired (FR at 10, 12, 14 months of age were 0.0280 +/- 0.01031, 0.0196 +/- 0.01050, 0.0158 +/- 0.00833 1/ms, respectively).

CONCLUSIONS

The MRI allows reliable in vivo assessment of the systolic and diastolic function in Tgalphaq*44 mice. In Tgalphaq*44 mice after few months of stable and compensated phase of the heart failure decompensation develops that involves impairment of both systolic and diastolic and leads to the fully symptomatic dilated cardiomyopathy. The precise molecular mechanisms of the systolic and diastolic dysfunction and their relative contribution to the heart failure progression in Tgalphaq*44 mice remain to be established.

Brains with different degrees of dysplasia show different patterns of neurodegenerative changes following pilocarpine-induced seizures. Histologic evidence of tissue damage correlated with MRI data

OBJECTIVE

Brain dysplasias produced by irradiation with gamma rays at various stages of prenatal development cause different post-natal susceptibility to seizures. To detect possible determinants of this difference, patterns of degenerative changes in the dysplastic brains following pilocarpine-induced epilepsy were analysed.

METHODS

Pregnant Wistar rats were exposed to a 1.0 Gy dose of gamma rays on gestation days 15 (E15) or 17 (E17). On post-natal day 60, their offspring received pilocarpine injections to evoke status epilepticus. Motor manifestations of seizure activity were observed continuously for 6 hours and rated. Six days following the status epilepticus, the rats were anesthetized and T(2)-weighted magnetic resonance (MR) images were obtained. Frontal sections of the brains were immunostained for immunoglobulins G (IgGs) to detect blood-brain barrier damage and IgG cell uptake and glial fibrillary acidic protein (GFAP) or S-100-beta protein to visualize astrocytes. Bandeiraea simplicifolia isolectin-B4 (BSI-B4) isolectin histochemistry was also performed to detect microglia/macrophages.

RESULTS

Tissue damages within epileptic brains as observed by light microscopy generally reflected changes in magnetic resonance imaging (MRI) at similar locations. Brains of rats irradiated on E15 or E17 and showing epileptic symptoms at comparable intensity also displayed different distribution of the pathologic changes. Among other post-epileptic changes, in rats irradiated on E17 as well as controls, the laterodorsal and ventrolateral thalamic nuclei showed signs of severe degeneration. In rats irradiated on E15, the nuclei were free of such changes.

CONCLUSIONS

The obtained data point to important differences in the pattern of propagation of epileptic activity in the dysplastic brains suffering from neuronal loss in functionally different structures.

The Macromolecular Polymers for the Preparation of Hydrodynamically Balanced Systems—Methods of Evaluation

Evaluation of macromolecular polymers used as excipients for the preparation of hydrodynamically balanced systems (HBS) was carried out. Hard gelatine capsules were filled with polymeric substances belonging to various chemical groups (chitosan, sodium alginate, hydroxypropylmethycellulose--HPMC). The following properties of the HBS were investigated: density, hydration, erosion and floating force. The solvent penetration process into the HBS was visualized using magnetic resonance imaging (MRI) technique. Densities of the HBS in hydrochloric acid (0.1 M) ranged from 0.37 g/cm3 to 0.71 g/cm3. Each polymer demonstrated different hydration/erosion abilities and floating properties. The maximum floating force (F(float max)) for capsules size 0, ranged from 26.7 mN (sodium alginate) to 64.7 mN (chitosan). HBS formulations also varied in time to reach maximum floating force (T(float max)). HPMC and sodium alginate formulation reached F(float max) within half an hour after immersion, while in the case of chitosan formulations (deacetylation degree (d.d.) 66% and d.d. 93%), the time was 184 minutes and 218 minutes respectively. The floating properties of the dosage forms were reliant on type of the polymer and the medium-fasted state simulated gastric fluid (FaSSGF) or fed state simulated gastric fluid (FeSSGF). The size of the HBS influenced the floating force value. The mechanisms of erosion and swelling of the polymeric matrices play a dominant role in flotation of the dosage forms.

Analysis of the diffusion weighted MR microscopy data of excised spinal cord of a rat on the basis of the model of restricted diffusion

Anisotropic diffusion in the excised rat spinal cord saturated with 0.9% saline was investigated using MR microimaging with b-values up to 8000 s/mm2 for different diffusion times. Non-exponential transversal diffusion decay found in white matter (WM) and gray matter (GM) was fitted with 2 components (the "fast" and the "slow"). Significantly smaller non-exponential dependence was found for the longitudinal diffusion in the WM. Obtained results corresponding to restricted diffusion in the range from approximately 2 to approximately 7 microm were correlated with axon diameter distribution in the WM obtained from transmission electron micrographs. It was concluded that observed diffusion anisotropy in the spinal cord might be entirely explained by presence of the slow transversal component, arising from the restricted diffusion. The strict analytical description of the diffusion decay in nervous tissue requires taking into account continuous distribution of the space-scale of the restricting barriers. The simplified two-component analysis may be applicable for visualization of the nervous tissue in clinical practice.

3D MR imaging of dental cavities-an in vitro study

A 3D spin-echo (3D SE) pulse sequence was used on a 4.7 T research MRI system to produce images of extracted human first molar tooth placed in CuSO4 water solution. The maximal resolution achieved was 35 x 63 x 300 microm3 in read and two phase directions, respectively. The high-intensity signal from water in solution together with the lack of signal from mineralized tooth tissue produce very good contrast allowing to visualize topography of outer and inner surfaces of the tooth. The 3D MR data were median filtered, binarized and then divided into separate segments corresponding to the inner tooth cavities and the hard tooth tissue. The topography of the root canals was visualized and the canals volume was calculated. The presented technique may be used for quantitative analysis of the root canal cavities shape and volume. The results of such an analysis may be applied for estimation of the quality of the impressional mapping methods in restorative dentistry or as an alternative non-impressional 3D mapping method.