MR image corrections for PET-induced gradient distortions.

MR image corrections for PET-induced gradient distortions. Phys Med Biol. 2018 Dec 18;: Authors: Gross-Weege N, Nolte T, Schulz V Abstract The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) by using PET inserts in existing MRI scanners is an attractive approach. When designing the PET insert, mutual influences of both imaging modalities need to be minimized. The gradient magnetic fields induce eddy currents in all conductive components of the PET insert. Eddy currents produce superimposing magnetic fields distorting the gradient magnetic field. However, the gradient magnetic fields determine how the MRI data is acquired in the k-space. A distorted gradient shape produces a distorted k-space trajectory which then results in a distorted image. The dynamic performance of the gradient system can be characterized by measuring its gradient impulse response function (GIRF). Knowledge of the GIRF enables to correct the k-space trajectory and thereby enables to reduce image distortions. We characterized the influence of a preclinical PET insert, the Hyperion IID, on the gradient performance of a 3-T MRI scanner. The GIRFs up to the second order spherical harmonics were determined with and without the PET insert by measuring frequency-swept gradient pulses with an NMR probe. We calculated a corrected k-space trajectory of a single-shot spiral sequence using the measured GIRFs. The low-pass characteristic of th...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research

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Discussion Pulmonary embolism (PE) is potentially life-threatening but fortunately rare event especially in the pediatric population. It was first described in children in 1861. PE is likely underreported because of minimal or non-specific clinical symptoms. The incidence is estimated at 0.05-4.2% with the 4.2% based on autopsy reports. It is probably also increasing as more central venous catheters (CVC) are used, and more children are surviving previously poor prognostic diseases. There is a bimodal distribution with cases
Source: - Category: Pediatrics Authors: Tags: Uncategorized Source Type: news
We report a case of invasive mucormycosis in 52 year-old woman. CT-scan and magnetic resonance imaging found a partial right sinus thrombosis associated with homolateral ethmoidal and maxillary sinusitis with submucosal inflammation. Histopathological examination of excised tissue was positive for mucormycosis. Our patient was treated by surgical debridement and a combination of amphotericin B and caspofungin, with a good outcome.
Source: Medical Mycology Case Reports - Category: Biology Source Type: research
Magnetic resonance imaging (MRI) could be a successful technology for understanding the severity ofmeningioma, according to a  studyrecently published inClinical Radiology. Determining if meningioma is high grade or low grade can help physicians decide how the tumor should be managed. Researchers from the American University Beirut Medical Center ventured to find out if MRI could help identify the meningioma grade before it ’s removed from the patient, making surgery easier and safer. The researchers analyzed scans of 71 patients who had undergone surgeries to remove intracranial meningiomas at America...
Source: radRounds - Category: Radiology Authors: Source Type: blogs
Publication date: Available online 20 September 2019Source: NeuropsychologiaAuthor(s): Jiwen Li, Mingyan Liu, Maoying Peng, Ke Jiang, Hong Chen, Juan YangAbstractRecent research has shown that relational self-esteem (RSE) carries important implications, especially in collectivistic cultures. In the present study, we aimed to investigate the neural mechanism underlying RSE and the behavioral and neural differences between RSE and personal self-esteem (PSE) in Chinese with interdependent self-construal. In Study 1, 581 participants completed a scale measuring RSE, the Rosenberg Personal Self-esteem Scale, and the Self-constr...
Source: Neuropsychologia - Category: Neurology Source Type: research
Conclusions: In MTC patients with increased Ctn and no known distant metastases, F-18-Dopa PET/CT is more sensitive to detect structural disease than any other imaging modality, including WB MRI. PMID: 31530235 [PubMed - as supplied by publisher]
Source: Thyroid : official journal of the American Thyroid Association - Category: Endocrinology Tags: Thyroid Source Type: research
CONCLUSION: Although PS being a clinical diagnosis, this study indicated that in patients whom PS was not suspected at the initial examination, 8.2% of them were finally diagnosed after MRI evaluations. Performing specific pelvic sequences as an adjunct to routine lumbar MRI can salvage underdiagnosed patients with PS and facilitate early detection of this pathological condition. PMID: 31529453 [PubMed - in process]
Source: Turkish Neurosurgery - Category: Neurosurgery Authors: Tags: Turk Neurosurg Source Type: research
Authors: Wei L, Osman S, Hatt M, El Naqa I Abstract Due to the recent developments of both hardware and software technologies, multimodality medical imaging techniques have been increasingly applied in clinical practice and research studies. Previously, the application of multimodality imaging in oncology has been mainly related to combining anatomical and functional imaging to improve diagnostic specificity and/or target definition, such as positron emission tomography/computed tomography (PET/CT) and single-photon emission computed tomography (SPECT)/CT. More recently, the fusion of various images, such as multi-...
Source: Quarterly Journal of Nuclear Medicine and Molecular Imaging - Category: Nuclear Medicine Tags: Q J Nucl Med Mol Imaging Source Type: research
CONCLUSIONS: Pelvic fracture MRI should be performed primarily in elderly female patients without adequate trauma. In patients with adequate trauma, MRI is of low value, especially as MRI diagnostics are performed with delay, resulting in later surgery. PMID: 31533165 [PubMed - as supplied by publisher]
Source: Zeitschrift fur Orthopadie und Unfallchirurgie - Category: Orthopaedics Tags: Z Orthop Unfall Source Type: research
Abstract Language comprehension during reading requires fine-grained management of saccadic eye movements. A critical question, therefore, is how the brain controls eye movements in reading. Neural correlates of simple eye movements have been found in multiple cortical regions, but little is known about how this network operates in reading. To investigate this question in the present study, participants were presented with normal text, pseudo-word text, and consonant string text in a magnetic resonance imaging (MRI) scanner with eyetracking. Participants read naturally in the normal text condition and moved t...
Source: Experimental Brain Research - Category: Neuroscience Authors: Tags: Exp Brain Res Source Type: research
CONCLUSIONS: MRI can provide important image-based measures of cardiac morphology that relate to disease severity and clinical outcomes in neonates with BPD. PMID: 31539272 [PubMed - as supplied by publisher]
Source: American Journal of Respiratory and Critical Care Medicine - Category: Respiratory Medicine Authors: Tags: Am J Respir Crit Care Med Source Type: research
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