MR imaging of teeth using a silent single point imaging technique (original) (raw)
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NMR Imaging in Dentistry: Relaxation and Diffusion Studies
Advances in Dental Research, 1987
Magnetic resonance imaging has been widely used for medical diagnosis in recent years. The knowledge of the proton spin-lattice relaxation time, T1, represents the basis for NMR imaging. In the present study, we measured T1 in saliva, gingival fluid, gingival blood, and inflamed gingiva by means of a pulsed NMR Fourier-transform spectrometer. From several measurements, we found the following average T1 values: in saliva, T1 = 2550 msec; in gingival fluid, T1 = 2085 msec; in gingival blood, T1 = 1515 msec; and in inflamed gingiva samples, T1 = 840 msec. In addition, electron paramagnetic resonance imaging was used to demonstrate the in vitro diffusion processes of spin-labeled molecules into tooth enamel by application of the linear magnetic field gradient to a conventional EPR spectrometer. The diffusion coefficient for the nitroxide spin-labeled molecules into tooth enamel was evaluated as D = 10-7 cm2 sec-1.
Assessment of structural changes of human teeth by low-field nuclear magnetic resonance (NMR)
Measurement Science and Technology, 2010
A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for assessment of age-related structural changes (dentin and pulp) of human teeth in vitro. The technique involves spin-spin relaxation measurement and inversion spin-spin spectral analysis methods. The spin-spin relaxation decay curve is converted into a T 2 distribution spectrum by a sum of single exponential decays. The NMR spectra from the extracted dentin-portion-only and dental pulp-cells-only were compared with the whole extracted teeth spectra, for the dentin and pulp peak assignments. While dentin and pulp are highly significant parameters in determining tooth quality, variations in these parameters with age can be used as an effective tool for estimating tooth quality. Here we propose an NMR calibration method-the ratio of the amount of dentin to the amount of pulp obtained from NMR T 2 distribution spectra can be used for measuring the age-related structural changes in teeth while eliminating any variations in size of teeth. Eight teeth (third molars) extracted from humans, aged among 17-67 years old, were tested in this study. It is found that the intensity ratio of dentin to pulp sensitively changes from 0.48 to 3.2 approaching a linear growth with age. This indicates that age-related structural changes in human teeth can be detected using the low-field NMR technique.
Magnetic resonance imaging of rodent teeth
Magma: Magnetic Resonance Materials in Physics, Biology, and Medicine, 1999
In this paper, the anatomical structures of rat jaws are studied using magnetic resonance imaging (MRI) with high spatial resolution. In vivo microimages of teeth from 3-and 12-week-old (young and adult) rats have been performed. A 2 T nuclear magnetic resonance microscope was used to collect, with multiple orientations, non-invasive 2D data images using the spin-echo technique, MRI appears well suited to give images of the oral area and may represent a useful tool for diagnosis of dental diseases and more particularly of pulp pathologies.
Simultaneous imaging of hard and soft biological tissues in a low-field dental MRI scanner
Scientific Reports, 2020
Magnetic Resonance Imaging (MRI) of hard biological tissues is challenging due to the fleeting lifetime and low strength of their response to resonant stimuli, especially at low magnetic fields. Consequently, the impact of MRI on some medical applications, such as dentistry, continues to be limited. Here, we present three-dimensional reconstructions of ex-vivo human teeth, as well as a rabbit head and part of a cow femur, all obtained at a field strength of 260 mT. These images are the first featuring soft and hard tissues simultaneously at sub-Tesla fields, and they have been acquired in a home-made, special-purpose, pre-medical MRI scanner designed with the goal of demonstrating dental imaging at low field settings. We encode spatial information with two pulse sequences: Pointwise-Encoding Time reduction with Radial Acquisition and a new sequence we have called Double Radial Non-Stop Spin Echo, which we find to perform better than the former. For image reconstruction we employ Alg...
Dental Magnetic Resonance Imaging: Making the Invisible Visible
Journal of Endodontics - J ENDODONT, 2011
IntroductionClinical dentistry is in need of noninvasive and accurate diagnostic methods to better evaluate dental pathosis. The purpose of this work was to assess the feasibility of a recently developed magnetic resonance imaging (MRI) technique, called SWeep Imaging with Fourier Transform (SWIFT), to visualize dental tissues.
Magnetic resonance imaging of human teeth
Journal of Endodontics, 1992
FIG 9. Six of the eight MR imaged levels of specimen 1, with corresponding drawings (D1 to D6) done from two separate images that show pulpal and periodontal detail. MR images shown here were selected to show pulpal detail at the expense of the periodontal image. PM, periodontal
Journal of Imaging
This narrative review aims to evaluate the current evidence for the application of magnetic resonance imaging (MRI), a radiation-free diagnostic exam, in some fields of dentistry. Background: Radiographic imaging plays a significant role in current first and second level dental diagnostics and treatment planning. However, the main disadvantage is the high exposure to ionizing radiation for patients. Methods: A search for articles on dental MRI was performed using the PubMed electronic database, and 37 studies were included. Only some articles about endodontics, conservative dentistry, implantology, and oral and craniofacial surgery that best represented the aim of this study were selected. Results: All the included articles showed that MRI can obtain well-defined images, which can be applied in operative dentistry. Conclusions: This review highlights the potential of MRI for diagnosis in dental clinical practice, without the risk of biological damage from continuous ionizing radiati...
Imaging tooth enamel using zero echo time (ZTE) magnetic resonance imaging
Proceedings of SPIE, 2015
In an event where many thousands of people may have been exposed to levels of radiation that are sufficient to cause the acute radiation syndrome, we need technology that can estimate the absorbed dose on an individual basis for triage and meaningful medical decision making. Such dose estimates may be achieved using in vivo electron paramagnetic resonance (EPR) tooth biodosimetry, which measures the number of persistent free radicals that are generated in tooth enamel following irradiation. However, the accuracy of dose estimates may be impacted by individual variations in teeth, especially the amount and distribution of enamel in the inhomogeneous sensitive volume of the resonator used to detect the radicals. In order to study the relationship between interpersonal variations in enamel and EPR-based dose estimates, it is desirable to estimate these parameters nondestructively and without adding radiation to the teeth. Magnetic Resonance Imaging (MRI) is capable of acquiring structural and biochemical information without imparting additional radiation, which may be beneficial for many EPR dosimetry studies. However, the extremely short T2 relaxation time in tooth structures precludes tooth imaging using conventional MRI methods. Therefore, we used zero echo time (ZTE) MRI to image teeth ex vivo to assess enamel volumes and spatial distributions. Using these data in combination with the data on the distribution of the transverse radio frequency magnetic field from electromagnetic simulations, we then can identify possible sources of variations in radiationinduced signals detectable by EPR. Unlike conventional MRI, ZTE applies spatial encoding gradients during the RF excitation pulse, thereby facilitating signal acquisition almost immediately after excitation, minimizing signal loss from short T2 relaxation times. ZTE successfully provided volumetric measures of tooth enamel that may be related to variations that impact EPR dosimetry and facilitate the development of analytical procedures for individual dose estimates.
MRI and Its Implications in Dentistry
International Journal of Medical Science And Diagnosis Research
Magnetic Resonance imaging (MRI) has become one of the most powerful diagnostic tools in radiology and diagnostic sciences. It is non-invasive and non-ionizing and the images are highly sensitive and specific with excellent soft tissue contrast. It gives excellent images of anatomic structures differing in proton density and other tissue characteristics. It can be used to assess intracranial and extracranial lesions particularly those involving the soft tissues. MRI has the shortcoming of being prone to magnetic susceptibility difference artefacts, caused by the presence of metallic materials such as dental restorative materials, implants and orthodontic appliances. All substances when placed in a magnetic field are magnetized to a degree which varies according to their magnetic susceptibility. Non precious dental alloys have the potential of causing image deformation or image voids. Dentists are not the only professionals implanting metal devices. Heart pacemakers and defibrillator...
Imaging human teeth by phosphorus magnetic resonance with nuclear Overhauser enhancement
Scientific reports, 2016
Three-dimensional phosphorus MR images ((31)P MRI) of teeth are obtained at a nominal resolution of 0.5 mm in less than 15 minutes using acquisition pulse sequences sensitive to ultra-short transversal relaxation times. The images directly reflect the spatially resolved phosphorus content of mineral tissue in dentin and enamel; they show a lack of signal from pulp tissue and reduced signal from de-mineralized carious lesions. We demonstrate for the first time that the signal in (31)P MR images of mineralized tissue is enhanced by a (1)H-(31)P nuclear Overhauser effect (NOE). Using teeth as a model for imaging mineralized human tissue, graded differences in signal enhancement are observed that correlate well with known mineral content. From solid-state NMR experiments we conclude that the NOE is facilitated by spin diffusion and that the NOE difference can be assigned to a higher water content and a different micro-structure of dentin. Thus, a novel method for imaging mineral content...