scholarly journals Magnetic Resonance Imaging for Assessment of Endodontic Instruments’ Precision during “L-Shaped” Model Root Canals Preparation

2021 ◽  
Vol 11 (3) ◽  
pp. 1051
Author(s):  
Tomasz Olek ◽  
Władysław P. Węglarz ◽  
Agata Trzcionka ◽  
Arkadiusz Dziedzic ◽  
Marta Tanasiewicz
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Root Canal ◽  
Spin Echo ◽  
Resonance Imaging ◽  
Root Canals ◽  
Mechanical Preparation ◽  
Before And After ◽  
Curved Root Canals

The purpose of the mechanical root canal preparation is to clean it and give it the right shape. The preparation should be carried out in a way that maintains the original curvature and initial orientation of the apical end. Insufficient root canal preparation may prevent effective chemical decontamination and obturation to the full working length. The study aims to evaluate the shaping ability and effectiveness of the NiTi rotary and reciprocating endodontic instruments, compared to standard hand files using magnetic resonance imaging based on spin echo. Material and methods: A comparative study of severely curved root canals’ shaping abilities using three NiTi systems and K-type hand files was performed, with 40 training “endo-blocks” presenting with “L-shaped” canal. The root canal topography and geometry “before” and “after” mechanical preparation obtained by the magnetic resonance imaging based on the spin echo was used. The main measurement was made using the RARE sequence, with slice thickness reduced to 100 micrometers. In order to improve the signal-to-noise ratio, NA = 25 was used. To minimize the measurement time, the field of view was limited to a cuboid 17 × 16 × 3 mm, with a resolution of 33 × 31 × 100 micrometers. Each 3D image consisted of 512 × 512 × 30 voxels. The imaging plane has been selected in such a way as to fully illustrate the course of curvature of the model root canal. For TR = 5 s and effective TE = 36 ms, TA was 1.5 h. Measurements were performed twice, before and after the preparation of endo-blocs with a selected type of endodontic tools. Results: The use of rotary NiTi instruments caused a substantial alteration in the curvature topography and angle of the canals and change in the curvature length. The substantial discrepancy was observed during the preparation of simulated root canals with the reciprocating instruments and the use of WaveOne files led to the largest volume variation. No dependence between the amount of material removed and the measured intracanal side was observed when NiTi instruments were used. Preparation with hand K-type files revealed a relationship between the measuring side and the amount of material removed, with the lower values obtained for the canals’ internal curvatures. Conclusions: All the studied endodontic instruments allow a safe preparation of curved root canals in simulating in vivo conditions. The abbreviation of original root canals topography does not seem to be significantly altered following mechanical preparation of simulated, severely curved root canals. The spin echo-based magnetic resonance imaging technique can be utilized for visualization of the internal topography of the root’s canals in vitro before and after their mechanical preparation in in vitro conditions. In the future, magnetic resonance microscopy may become a diagnostic tool supporting the work of a clinician.

Nichtinvasive Beurteilung aortokoronarer Venenbrücken mit Kernspintomographie

1989 ◽  
Vol 28 (06) ◽  
pp. 234-242 ◽  
Author(s):  
U. Sechtem ◽  
Sabine Langkamp ◽  
M. Jungehülsing ◽  
H. H. Hilger ◽  
H. Schicha ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Coronary Artery ◽  
Magnetic Resonance ◽  
Coronary Artery Bypass ◽  
Spin Echo ◽  
Artery Bypass ◽  
Graft Patency ◽  
Coronary Artery Bypass Grafts ◽  
Resonance Imaging ◽  
Low Sensitivity

Fortyfour patients with recent cardiac catheterization because of recurrent chest pain after coronary artery bypass surgery were studied by magnetic resonance imaging to evaluate graft patency. To assess the efficacy of this non-invasive method 92 coronary artery bypass grafts were examined by the spin-echo technique. ECG-gated transversal sections were acquired between the diaphragm and the aortic arch. The specificity of magnetic resonance imaging was 83% (48/58) for patent grafts. However, the sensitivity in the detection of occluded bypasses was only 56% (19/34). Despite the good specificity, clinical applications of this method are limited because of its low sensitivity.

Dependence of Blood Clot Lysis on the Mode of Transport of Urokinase into the Clot - A Magnetic Resonance Imaging Study in Vitro

1991 ◽  
Vol 65 (05) ◽  
pp. 549-552 ◽  
Author(s):  
A Blinc ◽  
G Planinšič ◽  
D Keber ◽  
O Jarh ◽  
G Lahajnar ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Pressure Difference ◽  
Volume Flow Rate ◽  
Blood Clot ◽  
Linear Regression Analysis ◽  
Imaging Study ◽  
Clot Lysis ◽  
Resonance Imaging

SummaryMagnetic resonance imaging was employed to study the dependence of clot lysing patterns on two different modes of transport of urokinase into whole blood clots. In one group of clots (nonperfused clots, n1 = 10), access of urokinase to the fibrin network was possible by diffusion only, whereas in the other group (perfused clots, n2 = 10) bulk flow of plasma containing urokinase was instituted through occlusive clots by a pressure difference of 3 .7 kPa (37 cm H2O) across 3 cm long clots with a diameter of 4 mm. It was determined separately that this pressure difference resulted in a volume flow rate of 5.05 ± 2.4 × 10−2 ml/min through occlusive clots. Perfused clots diminished in size significantly in comparison to nonperfused ones already after 20 min (p <0.005). Linear regression analysis of two-dimensional clot sizes measured by MRI showed that the rate of lysis was more than 50-times faster in the perfused group in comparison to the nonperfused group. It was concluded that penetration of the thrombolytic agent into clots by perfusion is much more effective than by diffusion. Our results might have some implications for understanding the differences in lysis of arterial and venous thrombi.

Preparation of Chlorotoxin-conjugated Superparamagnetic Nanoparticle and its Magnetic Resonance Imaging In Vitro

2016 ◽  
Vol 13 (7) ◽  
pp. 697-705 ◽  
Author(s):  
Chen Zhu ◽  
Xiao Enhua ◽  
Shang Quanliang ◽  
Kang Zhen ◽  
Tan Huilong ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Resonance Imaging

TEA-assistant synthesis of MOF-74 nanorods for drug delivery and in-vitro magnetic resonance imaging

2021 ◽  
Vol 315 ◽  
pp. 110900
Author(s):  
Jiaqi Hu ◽  
Yi Chen ◽  
Hui Zhang ◽  
Zhenxia Chen ◽  
Yun Ling ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Drug Delivery ◽  
Magnetic Resonance ◽  
Resonance Imaging

scholarly journals “Yokoyama procedure” efficacy on non-highly myopic patients with acquired esotropia and hypotropia

2019 ◽  
Vol 30 (4) ◽  
pp. 676-679
Author(s):  
Massimiliano Serafino ◽  
Matteo Scaramuzzi ◽  
Edoardo Villani ◽  
Paolo Nucci
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Axial Length ◽  
Lateral Rectus ◽  
Inclusion Criteria ◽  
Resonance Imaging ◽  
Spherical Equivalent Refraction ◽  
Before And After ◽  
Weighted Magnetic Resonance Imaging ◽  
The Mean

Objective: To assess the efficacy of “Yokoyama Procedure,” on non-highly myopic patients with acquired esotropia and hypotropia. Methods: The study involved 10 eyes of 5 patients with eso-hypotropia. Inclusion criteria were acquired esotropic-hypotropic strabismus with lateral rectus inferior displacement and superior rectus nasal displacement confirmed by magnetic resonance imaging, refractive errors between ±6 D, and axial length < 27 mm. Range of full duction movements and maximum angles of abduction-sursumduction was measured in each eye before and after surgery. All patients underwent T1- and T2-weighted magnetic resonance imaging. The surgery was aimed at creating a junction between the muscle bellies of the superior and lateral rectus muscles. This junction was made approximately 14 mm behind the insertions using a non-absorbable mersilene 5/0 suture (Yokoyama procedure). Results: Mean patient age was 64.8 ± 4.8 years. The mean globe axial length was 25.4 ± 0.76 mm and a mean corresponding spherical equivalent refraction of −3.7 ± 1.7 D was observed. Eight eyes on 10 had mild limitation in abduction, while the remaining 2 had no limitation. Three out of 10 eyes showed a moderate limited sursumduction, 5 eyes were categorized as mild, and the remaining 2 had no limitation. No evident post-operative limitation was present in any eye, in both abduction and sursumduction (p < 0.01). Pre-operative esotropia and hypotropia were, respectively, 32 ± 11 prismatic diopters and 25 ± 5 prismatic diopters, and they were significantly reduced after surgery as 9 ± 1.7 prismatic diopters and 6 ±1 prismatic diopters (p = 0.043), respectively. Conclusion: Yokoyama procedure is an effective, fast, reversible procedure to face eso-hypotropic acquired strabismus, even in patients with a clear magnetic resonance imaging displacement of superior and lateral rectus muscles, and absence of globe dislocation and of elevated myopia.

Ultra high resolution nonenhanced fast spin echo magnetic resonance imaging: Cost-effective screening for acoustic neuroma in patients with sudden sensorineural hearing loss

1998 ◽  
Vol 119 (4) ◽  
pp. 364-369 ◽  
Author(s):  
Robert L. Daniels ◽  
Clough Shelton ◽  
H. Ric Harnsberger
Keyword(s):  
Magnetic Resonance Imaging ◽  
Hearing Loss ◽  
Magnetic Resonance ◽  
Sensorineural Hearing Loss ◽  
Acoustic Neuroma ◽  
Spin Echo ◽  
Sudden Sensorineural Hearing Loss ◽  
Fast Spin Echo ◽  
Resonance Imaging ◽  
Fast Spin

The financial burden for the evaluation of patients for acoustic neuroma in an otolaryngology practice is substantial. Patients with sudden sensorineural hearing loss represent a portion of that population seen with unilateral, asymmetric auditory symptoms who require investigation for acoustic neuroma. For these patients, gadolinium-enhanced magnetic resonance imaging is the diagnostic gold standard. Auditory brain stem response testing has been used in the past as a screening test for acoustic neuroma, but its apparent sensitivity has fallen as the ability to image smaller acoustic neuromas has improved. Fast spin echo magnetic resonance imaging techniques without gadolinium have been shown to be as effective in the detection of acoustic neuroma as contrast-enhanced magnetic resonance imaging. Limited nonenhanced fast spin echo magnetic resonance imaging now provides an inexpensive alternative for high-resolution imaging of the internal auditory canal and cerebellopontine angle. Fast spin echo magnetic resonance imaging can now be done at a cost approximating auditory brain stem response testing while providing the anatomic information of contrast-enhanced magnetic resonance imaging. Cost analysis was done in the cases of 58 patients with sudden sensorineural hearing loss by comparing the costs for routine workup and screening of acoustic neuroma with the cost of fast spin echo magnetic resonance imaging with the use of screening protocols based on literature review. The potential cost savings of evaluating patients with sudden sensorineural hearing loss with fast spin echo magnetic resonance imaging for acoustic neuroma was substantial, with a 54% reduction in screening costs. In an era of medical economic scrutiny, fast spin echo magnetic resonance imaging has become the most cost-effective method to screen suspected cases of acoustic tumors at our institution by improving existing technology while reducing the cost of providing that technology and eliminating charges for impedance audiometry, auditory brain stem response testing, and contrast-enhanced magnetic resonance imaging.

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