Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 17 de 17
Filter
1.
J Plast Reconstr Aesthet Surg ; 75(8): 2671-2675, 2022 08.
Article in English | MEDLINE | ID: mdl-35659475

ABSTRACT

INTRODUCTION: Since 1972 when first pioneered, liposuction has developed and is now one of the commonest aesthetic procedures performed worldwide. Evidence of its application in aesthetic lipomodelling is widely known, but there are scant reports in the literature on the use of liposuction in more unusual cases. We report its use as a safe and successful method of contour correction in two cases of lipomyelomeningocoele (LMMC), a form of spina bifida. To our knowledge, this has never been reported before. METHOD: A prospective review was performed and both cases were followed up during the treatment period. Both patients were treated at the Royal Belfast Hospital for Sick Children. Patient charts were reviewed and magnetic resonance imaging was used. RESULTS: Two patients, aged 11 and 17 years, had a large LMMC over the lumbosacral area. Preoperative imaging was obtained in each case to ensure the procedure could safely avoid the underlying spinal cord structures. The use of the Microaire© suction device allowed precise fat extraction. Postoperative images demonstrate reduction of lipomatous bulk and improved contour. CONCLUSION: We have shown that when used with caution liposuction is a safe and effective technique for volume reduction of a LMMC in carefully selected cases.


Subject(s)
Lipectomy , Child , Humans , Lipectomy/methods , Prospective Studies , Suction
3.
Sci Rep ; 10(1): 12208, 2020 Jul 17.
Article in English | MEDLINE | ID: mdl-32678277

ABSTRACT

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

4.
Sci Rep ; 10(1): 8844, 2020 06 01.
Article in English | MEDLINE | ID: mdl-32483259

ABSTRACT

In modern magnetic resonance imaging, signal detection is performed by dense arrays of radiofrequency resonators. Tight-fitting arrays boost the sensitivity and speed of imaging. However, current devices are rigid and cage-like at the expense of patient comfort. They also constrain posture, limiting the examination of joints. For better ergonomics and versatility, detectors should be flexible, adapt to individual anatomy, and follow posture. Towards this goal, the present work proposes a novel design based on resonators formed by liquid metal in polymer tubes. Textile integration creates lightweight, elastic devices that are worn like pieces of clothing. A liquid-metal array tailored to the human knee is shown to deliver competitive image quality while self-adapting to individual anatomy and adding the ability to image flexion of the joint. Relative to other options for stretchable conductors, liquid metal in elastic tubes stands out by reconciling excellent electrical and mechanical properties with ease of manufacturing.

5.
IEEE Trans Med Imaging ; 39(4): 1138-1148, 2020 04.
Article in English | MEDLINE | ID: mdl-31567076

ABSTRACT

Developments in magnetic resonance imaging (MRI) in the last decades show a trend towards a growing number of array coils and an increasing use of a wide variety of sensors. Associated cabling and safety issues have been addressed by moving data acquisition closer to the coil. However, with the increasing number of radio-frequency (RF) channels and trend towards higher acquisition duty-cycles, the data amount is growing, which poses challenges for throughput and data handling. As it is becoming a limitation, early compression and preprocessing is becoming ever more important. Additionally, sensors deliver diverse data, which require distinct and often low-latency processing for run-time updates of scanner operation. To address these challenges, we propose the transition to reconfigurable hardware with an application tailored assembly of interfaces and real-time processing resources. We present an integrated solution based on a system-on-chip (SoC), which offers sufficient throughput and hardware-based parallel processing power for very challenging applications. It is equipped with fiber-optical modules serving as versatile interfaces for modular systems with in-field operation. We demonstrate the utility of the platform on the example of concurrent imaging and field sensing with hardware-based coil compression and trajectory extraction. The preprocessed data are then used in expanded encoding model based image reconstruction of single-shot and segmented spirals as used in time-series and anatomical imaging respectively.


Subject(s)
Image Processing, Computer-Assisted/methods , Magnetic Resonance Imaging/instrumentation , Magnetic Resonance Imaging/methods , Signal Processing, Computer-Assisted , Brain/diagnostic imaging , Equipment Design , Humans , Signal-To-Noise Ratio
6.
IEEE Trans Med Imaging ; 39(4): 997-1007, 2020 04.
Article in English | MEDLINE | ID: mdl-31484112

ABSTRACT

In magnetic resonance imaging, the use of array detection and the number of detector elements have seen a steady increase over the past two decades. As a result, per-channel analog connection via long coaxial cable, as commonly used, poses an increasing challenge in terms of handling, safety, and coupling among cables. This situation is exacerbated when complementary recording of radiofrequency transmission or NMR-based magnetic field sensing further add to channel counts. A generic way of addressing this trend is the transition to digital signal transmission, enabled by digitization and first-level digital processing close to detector coils and sensors in the magnet bore. The foremost challenge that comes with this approach is to achieve high dynamic range, linearity, and phase stability despite interference by strong static, audiofrequency, and radiofrequency fields. The present work reports implementation of a 16-channel in-bore receiver, performing signal digitization and processing with subsequent optical transmission over fiber. Along with descriptions of the system design and construction, performance evaluation is reported. The resulting device is fully MRI compatible providing practically equal performance and signal quality compared to state-of-the-art RF digitizers operating outside the magnet. Its use is demonstrated by examples of head imaging and magnetic field recording.


Subject(s)
Magnetic Resonance Imaging/instrumentation , Signal Processing, Computer-Assisted/instrumentation , Brain/diagnostic imaging , Equipment Design , Humans , Magnetic Fields , Magnetic Resonance Imaging/methods , Phantoms, Imaging
7.
IEEE Trans Biomed Eng ; 66(6): 1542-1548, 2019 06.
Article in English | MEDLINE | ID: mdl-30307855

ABSTRACT

The eGaIn coil on neoprene demonstrated in this paper presents a stretchable radio frequency receive coil for magnetic resonance imaging (MRI). The coil with dimensions [Formula: see text] is tuned to resonate at 128 MHz for 3 T MRI. We investigate the effect of stretching (up to 40% strain) and bending (50 mm radius of curvature) of the coil on the coil's resistance and resonance frequency. Measurements and simulations show a decrease in resonance frequency of 2.5 MHz per 10% strain. The higher resistivity of liquid metal compared to copper reduces the SNR of MRI scans by 34%; therefore, a tradeoff between flexibility and performance remains. Nevertheless, we have successfully performed MRI scans with the liquid metal coil.


Subject(s)
Magnetic Resonance Imaging/instrumentation , Metals, Heavy/chemistry , Computer Simulation , Equipment Design , Neoprene/chemistry , Phantoms, Imaging , Pliability , Signal-To-Noise Ratio
9.
IEEE Trans Med Imaging ; 38(6): 1420-1426, 2019 06.
Article in English | MEDLINE | ID: mdl-30582533

ABSTRACT

Stretchable magnetic resonance (MR) receive coils show shifts in their resonance frequency when stretched. An in-field receiver measures the frequency response of a stretchable coil. The receiver and coil are designed to operate at 128 MHz for a 3T MR scanner. Based on the measured frequency response, we are able to detect the changes of the resonance frequency of the coil. We show a proportional-integral-derivative controller that tracks the changes in resonance frequency and retunes the stretchable coil. The settling time of the control loop is less than 3.8ms. The retuning system reduces the loss in signal-to-noise ratio of phantom images from 1.6 dB to 0.3 dB, when the coil is stretched by 40% and the coil is retuned to 128 MHz.


Subject(s)
Magnetic Resonance Imaging/instrumentation , Magnetic Resonance Imaging/methods , Metals/chemistry , Equipment Design , Female , Humans , Male , Neoprene , Phantoms, Imaging , Signal-To-Noise Ratio
10.
Eur J Pediatr ; 177(9): 1363-1366, 2018 09.
Article in English | MEDLINE | ID: mdl-29872931

ABSTRACT

AbstractMagnetic resonance imaging (MRI) in preschool children is often challenging due to excessive motion artifacts. Sedation or general anesthesia (GA) are commonly used to prevent children from moving in the MRI scanner, with increased risk for cardiopulmonary complications and requirement for skilled personnel. Herein we investigated whether oral melatonin, a natural hormone implicated in circadian rhythm regulation, could be used as an alternative sedation method prior to the MRI in preschool children with musculoskeletal problems. Fifteen children with suspected juvenile idiopathic arthritis underwent a total of 16 MRI examinations following administration of 10 mg of oral melatonin; satisfactory images were obtained in all but one case, with no adverse events.Conclusion: The use of melatonin before the musculoskeletal MRI in preschool children is an effective, safe and inexpensive alternative to standard sedation and general anesthesia in preventing motion artifacts. What is known: • Magnetic resonance imaging (MRI) is a well-recognized diagnostic method to visualize synovial inflammation and changes of cartilage and bone in juvenile idiopathic arthritis.• MRI examination requires sedation or general anesthesia to ensure immobility in children who are uncooperative. What is new: • Additional to previous published studies we were able to show that melatonin for sedation for an MRI of joints, even without sleep deprivation, in the studied population may provide an alternative in children without behavioral problems, in order to avoid sedation/GA.

11.
IEEE Trans Med Imaging ; 37(2): 408-416, 2018 02.
Article in English | MEDLINE | ID: mdl-28910759

ABSTRACT

For magnetic resonance imaging of tissues with very short transverse relaxation times, radio-frequency excitation must be immediately followed by data acquisition with fast spatial encoding. In zero-echo-time (ZTE) imaging, excitation is performed while the readout gradient is already on, causing data loss due to an initial dead time. One major dead time contribution is the settling time of the filters involved in signal down-conversion. In this paper, a multi-rate acquisition scheme is proposed to minimize dead time due to filtering. Short filters and high output bandwidth are used initially to minimize settling time. With increasing time since the signal onset, longer filters with better frequency selectivity enable stronger signal decimation. In this way, significant dead time reduction is accomplished at only a slight increase in the overall amount of output data. Multi-rate acquisition was implemented with a two-stage filter cascade in a digital receiver based on a field-programmable gate array. In ZTE imaging in a phantom and in vivo, dead time reduction by multi-rate acquisition is shown to improve image quality and expand the feasible bandwidth while increasing the amount of data collected by only a few percent.


Subject(s)
Image Processing, Computer-Assisted/methods , Magnetic Resonance Imaging/methods , Humans , Phantoms, Imaging , Radio Waves
12.
Eur J Pediatr ; 177(9): 1359-1362, 2018 Sep.
Article in English | MEDLINE | ID: mdl-29249068

ABSTRACT

Magnetic resonance imaging (MRI) in preschool children is often challenging due to excessive motion artifacts. Sedation or general anesthesia (GA) is commonly used to prevent children from moving in the MRI scanner, with increased risk for cardiopulmonary complications and requirement for skilled personnel. Herein, we investigated whether oral melatonin, a natural hormone implicated in circadian rhythm regulation, could be used as an alternative sedation method prior to the MRI in preschool children with musculoskeletal problems. Fifteen children with suspected juvenile idiopathic arthritis underwent a total of 16 MRI examinations following administration of 10 mg of oral melatonin; satisfactory images were obtained in all but one case, with no adverse events. CONCLUSION: The use of melatonin before the musculoskeletal MRI in preschool children is an effective, safe, and inexpensive alternative to standard sedation and general anesthesia in preventing motion artifacts. What is Known: • Magnetic resonance imaging (MRI) is a well-recognized diagnostic method to visualize synovial inflammation and changes of cartilage and bone in juvenile idiopathic arthritis. • MRI examination requires sedation or general anesthesia to ensure immobility in children who are uncooperative. What is New: • Melatonin without sleep deprivation is efficacious and safe alternative to conventional sedation and general anesthesia before the musculoskeletal contrast-enhanced MRI in preschool children with JIA with timely insertion of intravenous cannula.


Subject(s)
Arthritis, Juvenile/diagnostic imaging , Central Nervous System Depressants/administration & dosage , Conscious Sedation/methods , Magnetic Resonance Imaging/methods , Melatonin/administration & dosage , Child, Preschool , Humans
13.
Childs Nerv Syst ; 34(2): 199-203, 2018 02.
Article in English | MEDLINE | ID: mdl-29249075

ABSTRACT

PURPOSE: Cerebral arteriovenous malformations (AVM) are uncommon lesions. They are most often presented in childhood as intracranial hemorrhage. The aim of this report is to present the use of transcranial color-coded duplex sonography (TCCS) in detection of AVMs in children suffering headache. METHODS: This report describes five pediatric patients with headache and cerebral AVM which were initially discovered by TCCS. Diagnosis was confirmed by magnetic resonance imaging and digital subtraction angiography. RESULTS: In all patients, TCCS showed saccular enlargement of the vessels with a multicolored pattern corresponding to the different directions of blood flow. Spectral analysis showed significantly high flow systolic and diastolic velocities and low resistance index. CONCLUSIONS: In this report, we describe TCCS as a valuable non-invasive, harmless, low-cost, widely available method for the detection and follow-up of hemodynamic changes of AVMs in children with headache, before and after treatment.


Subject(s)
Intracranial Arteriovenous Malformations/diagnostic imaging , Ultrasonography, Doppler, Transcranial/methods , Adolescent , Angiography, Digital Subtraction , Anterior Cerebral Artery/diagnostic imaging , Cerebral Angiography , Child , Female , Headache/etiology , Hemodynamics , Humans , Intracranial Arteriovenous Malformations/complications , Magnetic Resonance Angiography , Magnetic Resonance Imaging , Male , Middle Cerebral Artery/diagnostic imaging , Posterior Cerebral Artery/diagnostic imaging , Ultrasonography, Doppler, Color
14.
Adv Mater ; 29(44)2017 Nov.
Article in English | MEDLINE | ID: mdl-29027724

ABSTRACT

Stretchable conductors based on eutectic gallium-indium (eGaIn) alloy are patterned on a polychloroprene substrate (neoprene foam) using stencil printing. By tuning the amount of eGaIn on the neoprene substrate, different strain-sensitivity of electrical resistance is achieved. Conductors with a layer of eGaIn, which adsorbs to the walls of 60-100 µm wide neoprene cells, change their electrical resistance for 5% at 100% strain. When the amount of eGaIn is increased, the cells are filled with eGaIn and the strain-sensitivity of the electrical resistance rises to 300% at 100% strain. The developed conductors are patterned as stretchable on-body coils for receiving magnetic signals in a clinical magnetic resonance imaging setup. First images with a stretchable coil are acquired on an orange and compared to the images that are recorded using a rigid copper coil of the same size.

15.
IEEE Trans Biomed Circuits Syst ; 11(6): 1245-1255, 2017 12.
Article in English | MEDLINE | ID: mdl-29293422

ABSTRACT

Magnetic resonance imaging (MRI) is among the most important medical imaging modalities. Coil arrays and receivers with high channel counts (16 and more) have to be deployed to obtain the image quality and acquisition speed required by modern clinical protocols. In this paper, we report the theoretical analysis, the system-level design, and the circuit implementation of the first receiver IC (RXIC) for clinical MRI fully integrated in a modern CMOS technology. The dual-channel RXIC sits directly on the sensor coil, thus eliminating any RF cable otherwise required to transport the information out of the magnetic field. The first stage LNA was implemented using a noise-canceling architecture providing a highly reflective input used to decouple the individual channels of the array. Digitization is performed directly on-chip at base-band by means of a delta-sigma modulator, allowing the subsequent optical transmission of data. The presented receiver, implemented in a CMOS technology, is compatible with MRI scanners up to . It reaches sub- noise figure for MRI units and features a dynamic range up to at a power consumption below per channel, with an area occupation of . Mounted on a small-sized printed circuit board (PCB), the receiver IC has been employed in a commercial MRI scanner to acquire in-vivo images matching the quality of traditional systems, demonstrating the first step toward multichannel wearable MRI array coils.


Subject(s)
Magnetic Resonance Imaging/methods , Equipment Design , Signal-To-Noise Ratio
16.
Brain Dev ; 39(1): 89-92, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27449889

ABSTRACT

Muscular hypertrophy secondary to denervation is very rare, but well-documented phenomena in adults. This is the first report of a child with neurogenic unilateral hypertrophy due to S1 radiculopathy. A 12-year-old girl presented with left calf hypertrophy and negative history of low back pain or trauma. The serum creatinine kinase level and inflammatory markers were normal. Magnetic resonance imaging showed muscle hypertrophy of the left gastrocnemius and revealed a protruded lumbar disc at the L5-S1 level. The protruded disc abuts the S1 root on the left side. Electromyography showed mild left S1 radiculopathy. Passive stretching and work load might clarify the origin of neurogenic hypertrophy but there is still a need for further evidence. Clinical, laboratory, magnetic resonance imaging and electromyography findings showed that S1 radiculopathy could be a cause of unilateral calf swelling in youth even in the absence of a history of back or leg pain.


Subject(s)
Intervertebral Disc Displacement/complications , Leg/diagnostic imaging , Muscle, Skeletal/diagnostic imaging , Muscular Diseases/etiology , Radiculopathy/complications , Child , Female , Humans , Hypertrophy/diagnostic imaging , Hypertrophy/etiology , Hypertrophy/physiopathology , Intervertebral Disc Displacement/diagnosis , Intervertebral Disc Displacement/physiopathology , Lumbar Vertebrae , Magnetic Resonance Imaging , Muscular Diseases/diagnostic imaging , Muscular Diseases/physiopathology , Radiculopathy/diagnostic imaging , Radiculopathy/physiopathology
17.
Annu Int Conf IEEE Eng Med Biol Soc ; 2016: 4975-4978, 2016 Aug.
Article in English | MEDLINE | ID: mdl-28269385

ABSTRACT

This paper presents a working prototype of a wearable patient monitoring device capable of recording the heart rate, blood oxygen saturation, surface temperature and humidity during an magnetic resonance imaging (MRI) experiment. The measured values are transmitted via Bluetooth low energy (LE) and displayed in real time on a smartphone on the outside of the MRI room. During 7 MRI image acquisitions of at least 1 min and a total duration of 25 min no Bluetooth data packets were lost. The raw measurements of the light intensity for the photoplethysmogram based heart rate measurement shows an increased noise floor by 50LSB (least significant bit) during the MRI operation, whereas the temperature and humidity readings are unaffected. The device itself creates a magnetic resonance (MR) signal loss with a radius of 14 mm around the device surface and shows no significant increase in image noise of an acquired MRI image due to its radio frequency activity. This enables continuous and unobtrusive patient monitoring during MRI scans.


Subject(s)
Magnetic Resonance Imaging/instrumentation , Monitoring, Physiologic/instrumentation , Telemetry/instrumentation , Clothing , Humans
SELECTION OF CITATIONS
SEARCH DETAIL
...