Magnetic resonance imaging

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Value of magnetic resonance imaging for diagnosis of dentigerous cyst

Value of magnetic resonance imaging for diagnosis of dentigerous cyst

[5] F. A. Probst, M. Probst, C. Pautke et al., “Magnetic resonance imaging: a useful tool to distinguish between keratocystic odontogenic tumours and odontogenic cysts,” British Journal of Oral and Maxillofacial Surgery, vol. 53, no. 3, pp. 217–222, 2015. [6] K. Srinivasan, A. Seith Bhalla, R. Sharma, A. Kumar, A. Roychoudhury, and O. Bhutia, “Difusion-weighted imaging in the evaluation of odontogenic cysts and tumours,” British Journal of Radiology, vol. 85, no. 1018, pp. e864–e870, 2012. [7] M. Minami, T. Kaneda, K. Ozawa et al., “Cystic lesions of

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Cardiac motion and deformation estimation in tagged magnetic resonance imaging

Cardiac motion and deformation estimation in tagged magnetic resonance imaging

Tagged Magnetic Resonance Imaging is an imaging technique that induces a spatial line or grid pattern in the tissue of interest by spatially presaturating the tissue magnetization (Figure 1.3). This image modality differs from the other MRI acquisitions in the combination of radio-frequency (RF) and gradient pulses in order to define a regular pattern on the image. These patterns are called tags and they move and deform with the myocardium. The tags can be used to locally study the heart deformation. As advantages, the presence of tags on the myocardium wall makes studying the regional wall deformation easier and simplifies the assessment of certain motion components, such torsion. Nevertheless, the analysis of these datasets is challenging due to tag fading, the relatively low spatial resolution and the big variability in terms of tag properties between datasets, making it hard to delineate the cardiac anatomy (Figure 1.3) [16-18].
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Low-Field Magnetic Resonance Imaging of Canine Hydrocephalus

Low-Field Magnetic Resonance Imaging of Canine Hydrocephalus

The aim of presented study was to evaluate selected surface spine coil, and low- field magnetic resonance (MR) selected sequences in diagnosing hydrocephalus in dogs. This paper discusses 19 dogs (14 canine patients with hydrocephalus and 5 healthy dogs), of five breeds, subjected to low-field magnetic resonance imaging (MRI) of hydrocephalus. Area of the lateral ventricles and brain were examined in dogs with hydrocephalus using low-field MRI (at 0.25 Tesla). The MRI of FSE REL, SE, FLAIR, STIR, 3D HYCE, T3DT1, GE STIR 3D and 3D SHARC sequences with an indication of the most effective sequences are described. Additionally, coils for MR were compared, and models for infusion anesthesia were described. As a result of performed study all estimated sequences were diagnostically useful. However, spinal coil No. 2 (ESAOTE) was the most optimal for examining and positioning the cranium.
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Prostate Cancer: The Role of Multiparametric Magnetic Resonance Imaging

Prostate Cancer: The Role of Multiparametric Magnetic Resonance Imaging

Multiparametric Magnetic Resonance Imaging has been increasingly used for detection, localization and staging of prostate cancer over the last years. It combines high-resolution T2 Weighted-Imaging and at least two functional techniques, which include Dynamic Contrast–Enhanced Magnetic Resonance Imaging, Diffusion-Weighted Imaging, and Magnetic Resonance Imaging Spectroscopy. Although the combined use of a pelvic phased-array and an Endorectal Coil is considered the state-of-the-art for Magnetic Resonance Imaging evaluation of prostate cancer, Endorectal Coil is only absolute mandatory for Magnetic Resonance Imaging Spectroscopy at 1.5 T. Sensitivity and specificity levels in cancer detection and localization have been improving with functional technique implementation, compared to T2 Weighted-Imaging alone. It has been particularly useful to evaluate patients with abnormal PSA and negative biopsy. Moreover, the information added by the functional techniques may correlate to cancer aggressiveness and therefore be useful to select patients for focal radiotherapy, prostate sparing surgery, focal ablative therapy and active surveillance. However, more studies are needed to compare the functional techniques and understand the advantages and disadvantages of each one. This article reviews the basic principles of prostatic mp-Magnetic Resonance Imaging, emphasizing its role on detection, staging and active surveillance of prostate cancer.
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Magnetic resonance imaging of small bowel crohn’s disease

Magnetic resonance imaging of small bowel crohn’s disease

Crohn’s disease (CD) is a chronic relapsing inflammatory disease of the gastrointestinal tract, which mostly affects young patients. Imaging techniques form a very important part for the evaluation of CD and for monitoring disease progression or response to ther- apy. Currently, imaging of CD is increasingly being performed by cross-sectional modalities, i.e. multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI), since these techniques allow for simultaneous visualization of luminal, mural and extraintestinal disease extension. MR enterography has the potential to safely and noninvasively accomplish the imaging needs of patients with Crohn disease without exposing them to ionizing radiation. The new imaging paradigm should contemplate patient safety as a very important aspect when assessing the role of an imaging modality in comparison with others. For this reason, MRI may be the preferred modality for evaluation of small bowel disease, especially in young patients in the setting of CD, considering that the major- ity will undergo frequent repeat studies. Also, the information on disease activity is not matched by any other imaging method. In this review article, the authors discuss the essential aspects of MR evaluation of CD, including protocol and imaging findings, also referring the advantages over other radiological studies, concerning safety, accuracy and potential importance for therapeutic approach.
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Technology Governance in Radiology The example of Magnetic Resonance Imaging

Technology Governance in Radiology The example of Magnetic Resonance Imaging

It is not an easy task, to assess magnetic resonance imaging since it includes aspects of epidemiology, bio-statistics, clinical efficacy determination, outcomes assessment and knowledge of the technical and medical bases of imaging method (Thornbury and Fryback 1992). There are too many different knowledge fields to tackle. Also that means such assessment process should always involve different scientific and technical competences. In 1997, Fireberg et al. proposed a hierarchical conceptual framework for use in the evaluation and comparison of diagnostic imaging for imaging tests. According to Gazelle and colleagues (cf. Gazelle et al. 2005), this approach was later adopted and modified by others, such as Fryback (1983), Fryback et al. (1991), Dixon (1997) and Hunink (1998). This model however, wasn’t new, since it has been described In the early 1970’s parts of the levels began to de described and its earliest form was published in a paper by Fryback in 1983 (Thornbury and Fryback 1992). Such model also can serve as a structure for a design of scientific research that can be achieved to assess the impact and usefulness of MR imaging. In a simple way, this hierarchical model, takes into account six levels of efficacy according to Fryback and Thornbury (1992):
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Using magnetic resonance imaging to evaluate dendritic cell-based vaccination.

Using magnetic resonance imaging to evaluate dendritic cell-based vaccination.

Cancer immunotherapy with antigen-loaded dendritic cell-based vaccines can induce clinical responses in some patients, but further optimization is required to unlock the full potential of this strategy in the clinic. Optimization is dependent on being able to monitor the cellular events that take place once the dendritic cells have been injected in vivo, and to establish whether antigen-specific immune responses to the tumour have been induced. Here we describe the use of magnetic resonance imaging (MRI) as a simple, non-invasive approach to evaluate vaccine success. By loading the dendritic cells with highly magnetic iron nanoparticles it is possible to assess whether the injected cells drain to the lymph nodes. It is also possible to establish whether an antigen-specific response is initiated by assessing migration of successive rounds of antigen-loaded dendritic cells; in the face of a successfully primed cytotoxic response, the bulk of antigen-loaded cells are eradicated on-route to the node, whereas cells without antigen can reach the node unchecked. It is also possible to verify the induction of a vaccine-induced response by simply monitoring increases in draining lymph node size as a consequence of vaccine-induced lymphocyte trapping, which is an antigen-specific response that becomes more pronounced with repeated vaccination. Overall, these MRI techniques can provide useful early feedback on vaccination strategies, and could also be used in decision making to select responders from non-responders early in therapy.
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Magnetic resonance imaging urodynamics: technique development and preliminary results

Magnetic resonance imaging urodynamics: technique development and preliminary results

Simultaneously, magnetic resonance imaging was performed by using 1.5 T (Magneton Sonata Maestro Class, Siemens, Erlangen, Germany) with a 6-channel belt type surface coil placed around the patient at the level of the symphysis pubis. Morphological T2 true FISP (true fast imaging with steady-state precession TR 4.5, TE 2.3) weighted images were taken in sagittal plane during 360 seconds at a speed of 1 frame per second.

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Glomus Tumors: Symptom Variations and  Magnetic Resonance Imaging for Diagnosis

Glomus Tumors: Symptom Variations and Magnetic Resonance Imaging for Diagnosis

he typical clinical symptoms of glomus tumor of the inger are localized tenderness, severe paroxysmal pain, and cold sen- sitivity. Despite this knowledge, clinicians oten have diiculty diagnosing this condition because of variations in symptom presentation and nonspecific symptoms of glomus tumors. It is not uncommon for patients to remain undiagnosed or mis- diagnosed for many years. In such cases, an imaging modality, such as magnetic resonance (MR) imaging, can provide clues. To the best of our knowledge, few publications have reported on the usefulness of MR imaging in diagnosing glomus tumors in patients exhibiting nonspeciic symptoms. In this study, we present 21 cases of glomus tumor of the hand for which MR imaging played a critical role in forming an accurate diagnosis.
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Iron oxide nanoparticle-micelles (ION-micelles) for sensitive (molecular) magnetic particle imaging and magnetic resonance imaging.

Iron oxide nanoparticle-micelles (ION-micelles) for sensitive (molecular) magnetic particle imaging and magnetic resonance imaging.

2000] (PEG2000–DSPE) lipids into ultrapure water at 80 uC (Figure. 2C–D). ION-Micelles were separated from micelles not containing an iron oxide core using ultracentrifugation and subsequently the ION-Micelles were redispersed in HEPES- buffered saline (HBS) at pH 7.4. The dispersion state of the ION-Micelles in HBS was studied using cryogenic-TEM (cryo- TEM) and dynamic light scattering (DLS). Figure 4A–B shows typical high-resolution cryo-TEM images of ION-Micelles. The ION-Micelles were mostly dispersed in HBS as single particles or as small aggregates of nanoparticles. Occasionally, also larger, worm-like aggregates were observed (Figure 4C). Other lipidic structures, such as liposomes and (empty) micelles, were not observed. Figure 4D shows the ION-Micelle hydrodynamic size- distribution obtained from an intensity-weighted analysis of the time correlation function measured with DLS. One dominant peak was observed at 47 nm for the ION micelles. The minor peak at larger sizes was indicative of a small fraction of aggregated nanoparticles, which matches well with the cryo-TEM findings (Figure 4A–C). This peak disappeared in the number-weighted analysis (Figure 4E), implying that the relative contribution of the larger sized aggregates to the overall size-distribution was negligible. The hydrodynamic diameter of the ION-Micelles obtained using number-weighted analysis was 38 nm, which corresponds well with the nanoparticles core size-measurements (25 nm, Figure 3B). The apparent increase of the hydrodynamic size as determined by DLS compared to the nanoparticles core size measured by TEM is caused by the (hydrated) PEG2000- DSPE coating of the particles and the fact that a fraction of the particles contains multiple iron oxide cores. The hydrodynamic diameter of the ION-Micelles was similar to Resovist, approxi- mately a factor two larger than Sinerem and a factor two smaller than Endorem (Table 1). The magnetic properties of the ION- Micelles were analyzed using a vibrating sample magnetometer (VSM). The ION-Micelles behaved superparamagnetically at room-temperature (RT), as the magnetization curve had no hysteresis (Figure 5A). The saturation magnetization of the ION- Micelles was found to be 82 Am 2 /kg Fe 3 O 4 , which is relatively
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Correction of Spatial Distortion in Magnetic Resonance Imaging

Correction of Spatial Distortion in Magnetic Resonance Imaging

The Spatial Distortions, or according to some authors Geometric Distortions, in MRI can be classi- fied into two groups: hardware-related and tissue-related, depending on the cause of the distortion. The hardware-related distortions are caused essentially by the inhomogeneity in the main magnet, the nonlinearity in the gradient fields and the eddy currents associated to switching gradient coils. The magnet field’s inhomogeneity is caused by deformations in the main magnet, which will produce a different magnetic excitation in the hydrogen atoms, and therefore will produce errors in the readings, because the spins are not excited in the way it was predicted. This can easily be corrected using shimming coils to adjust the inhomogeneities of the main magnet [3, 4, 12]. According to Wang and Doddrell [3] inhomogeneities distortion decreases with the increase of the used gradient strength, for instance in a MR with 1,5 T with a gradient of 1,5 mT/m, the distortion is of 1mm, but if the gradient is 3 mT/m, the distortion will be half of the anterior. This cause of distortion occurs along the readout and slice selection direction, but not along the phase encoding direction, as phase encoding is not sensitive to any field inhomogeneities.
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Magnetic resonance imaging: dynamic contrast enhancement and diffusion-weighted imaging to identify malignant cervical lymph nodes

Magnetic resonance imaging: dynamic contrast enhancement and diffusion-weighted imaging to identify malignant cervical lymph nodes

In this study, we propose a novel method of MRI incorporating anatomical and vascular information to improve the evaluation of lymph nodes. The addition of diffusion-weighted imaging (DWI)—to determine the ap- parent diffusion coefficient (ADC)—and dynamic contrast enhancement (DCE)—to quantify perfusion and vascu- larity—allows metastatic (malignant) lymph nodes to be distinguished from reactive (benign) lymph nodes. Our objective was to assess the ability of such methods to dif- ferentiate between benign and malignant lymph nodes.

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A guide for functional magnetic resonance imaging

A guide for functional magnetic resonance imaging

Constantly gaining increased popularity among clinicians and researchers, fMRI is presently a promising tool for studying the brain function in living humans, both in healthy conditions and in disease. However, it has a complex workflow (summarized in figure 2) that implicates knowledge of paradigm design, imaging artifacts, complex MRI protocol definition, a multitude of preprocessing and analysis methods in several software packages, statistical analyzes, and in results interpretation. In addition, fMRI data can be analyzed with a large quantity of commonly used tools, with minor consensuses on how, when, or whether to apply each one. This situation may introduce considerable variability in the analysis outcome. A recent publication [28] identified 6912 slightly different paths through the analysis pipeline, resulting in 34560 different sets of results for the same dataset. Several papers and books describing the main technical issues and pitfalls related to both intrinsic and evoked fMRI analyses have been published [29-36].
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Self-assembled nanoparticles as new smart contrast agents for magnetic resonance imaging

Self-assembled nanoparticles as new smart contrast agents for magnetic resonance imaging

The pH-sensitive CAs are of interest to tumor MRI imaging, because a common feature of cancerous tissues is a significantly lower extracellular pH as compared to healthy tissues. Thus, pH seems to be a promising parameter for detecting early stage cancer (Hartman et al., 2008; Gillies, Raghunand, Garcia-Martin, & Gatenby, 2004). To this aim, Zhang and colleagues created a pH-sensitive Gd(III) complex of a DOTA tetramide derivative. They observed an interesting behavior of the complex relaxivity versus pH. Indeed, starting from pH 4, the relaxivity first increased until pH 6 and then decreased until reaching a minimum at pH 8.5. It remained at this minimum between pH 8.5 and 10.5 and then increased again (Zhang, Wu, & Sherry, 1999). Aime and coworkers reported a pH-sensitive CA with Gd(III)-chelates and ornithin residues. The chelates were conjugated to the amino acid chain via squaric esters, which readily reacts with amines. At low pH, the amines are protonated and do not interact with the squaric ester residues. When the pH increases in a range of 4.5 to 8.5, the amine side chains become deprotonated and interact with squaric ester linkers. This interaction rigidifies the polymer creating and increasing relaxivity (Aime et al., 1999a). Also Hartman and colleagues synthetised ultrashort singe-walled carbon nanotube capsules that provided extremely high and pH-dependent relaxivity. These so-called gadonanotubes showed an increased relaxivity upon a decrease in pH from 7.4 to 7.0 (Hartman et al., 2008).
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Fetal eye movements on magnetic resonance imaging.

Fetal eye movements on magnetic resonance imaging.

Table S2 Quantitative data on right and left eyeball position in a 26 GW old fetus, measured on sequential frames of the axial dynamic SSFP sequence shown in Figure 3a.. (DOCX).[r]

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Radiol Bras  vol.47 número4

Radiol Bras vol.47 número4

Imaging findings are very similar for both DCSF and CCF, but it is possible to differentiate them. Among the available imaging methods – orbital Doppler ultrasonogra- phy (US), computed tomography (CT), magnetic resonance imaging (MRI) and digital subtraction angiography (DSA) –, the latter is considered the gold-standard for the diagno- sis and classification of cavernous sinus AVF.

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Rev. Assoc. Med. Bras.  vol.62 número4

Rev. Assoc. Med. Bras. vol.62 número4

Idiopathic granulomatous mastitis is a rare disorder of unknown etiology. This disease occurs mostly in young women and often after the lactation period. Wom- en usually present with a fixed, painful mass, sparing the retroareolar region, as- sociated with skin thickening and possible ulceration that mimics carcinoma. Nipple discharge can be present and bilateral involvement may occur in up to 25% of cases. In this case report, we present a typical case of histologically con- firmed idiopathic granulomatous mastitis, highlighting the imaging findings, including magnetic resonance imaging (MRI), which may favor this diagnosis and enable better clinical management of these patients.
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Radiol Bras  vol.46 número2

Radiol Bras vol.46 número2

tant to note that, despite the continuous progress of imaging methods, particularly magnetic resonance imaging, searching for a correct diagnosis of prostate cancer, transrectal ultrasound (US) guided biopsy still plays a fundamental role for histopathological confirmation. Although such procedure is considered secure and also well tolerated by most patients, studies demonstrating com- plications in up to 73% of patients cannot be ignored (3) , leading

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Radiol Bras  vol.39 número3 en a02v39n3

Radiol Bras vol.39 número3 en a02v39n3

On the other hand, magnetic resonance imaging (MRI) provides significant information on tumor localization, extension to metaphysis and to adjacent soft tissues. Chondroblastomas present hyposignal in T1-weighted images and variable signal in T2-weighted images, usually with peripheral ring of marked T2-hyposignal in all the sequences. Central hyposignal is observed in T2-weighted images resulting from the predominance of a less prominent chondroid matrix, chondroblasts, calcifications and hemosiderin deposits in the lesion. Similarly to CT, RMI can show fluid-fluid level.

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Rev. bras.oftalmol.  vol.73 número3

Rev. bras.oftalmol. vol.73 número3

Cavernous sinus thrombosis (CST) is a rare condition, usually results from a late complication of an infection of the paranasal sinuses. Other causes include prothrombotic disorders, anemia and trauma.The signs and symptoms are extremely varied and nonspecific, being the diagnosis made through magnetic resonance imaging (MRI). The authors present a 75-year-old woman, admitted in the emergency room complaining of ocular pain in the right eye (RE), red eye and frontal headache. She presented on ophthalmic examination of the RE: dilated episcleral vessels, nuclear cataract and a relative afferent pupillary defect. Fundoscopy examination of the RE revealed disc edema with nasal disc margin blurred, small dot hemorrhages and vascular tortuosity. The MRI angiography confirmed the diagnosis and the patient was treated with low molecular weight heparin. Despite treatment of CST is directed to the causal situation, being shown that anticoagulation is associated with reduction in mortality.
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