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Journal Cover Magnetic Resonance Materials in Physics, Biology and Medicine
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0968-5243 - ISSN (Online) 1352-8661
     Published by Springer-Verlag Homepage  [2209 journals]   [SJR: 0.821]   [H-I: 36]
  • Effect of acute hyperglycemia on moderately hypothermic GL261 mouse glioma
           monitored by T1-weighted DCE MRI
    • Abstract: Objective We sought to evaluate the effects of acute hyperglycemia induced by intraperitoneal injection of glucose (2.7 g/kg) on vascular delivery to GL261 mouse gliomas kept at moderate hypothermia (~30 °C). Materials and methods Seven GL261 glioma-bearing mice were studied by T1-weighted DCE MRI before and after an injection of glucose (n = 4) or saline (n = 3). Maximum relative contrast enhancement (RCE) and initial area under the enhancement curve (IAUC) were determined in each pixel. Results The mean tumor parameter values showed no significant changes after injecting either saline (RCE −5.9 ± 5.0 %; IAUC −3.7 ± 3.6 %) or glucose (RCE −1.6 ± 9.0 %; IAUC +0.6 ± 6.4 %). Pixel-by-pixel analysis revealed small post-injection changes in RCE and IAUC between the glucose and saline groups, all within 13 % range of their baseline values. Conclusion Perturbing the metabolism of GL261 tumors kept at moderate hypothermia with hyperglycemia did not induce significant changes in the permeability/perfusion of these tumors. This is relevant for future studies with this model since regional differences in glucose accumulation could thus reflect basal heterogeneities in vasculature and/or metabolism of GL261 tumors.
      PubDate: 2014-06-11
  • Fast water concentration mapping to normalize        class="a-plus-plus">1H MR spectroscopic imaging
    • Abstract: Object To propose a fast and robust acquisition and post-processing pipeline that is time-compatible with clinical explorations to obtain a proton density (ρ) map used as a reference for metabolic map normalization. This allows inter-subject and inter-group comparisons of magnetic resonance spectroscopic imaging (MRSI) data and longitudinal follow-up for single subjects. Materials and methods A multi-echo T 2 * mapping sequence, the XEP sequence for B 1 + -mapping and Driven Equilibrium Single Pulse Observation of T 1—an optimized variable flip angle method for T 1 mapping used for both B 1 − -mapping and M 0 calculation—were used to determine correction factors leading to quantitative water proton density maps at 3T. Normalized metabolite maps were obtained on a phantom and nine healthy volunteers. To show the potential use of this technique at the individual level, we also explored one patient with low-grade glioma. Results Accurate ρ maps were obtained both on phantom and volunteers. After signal normalization with the generated ρ maps, metabolic concentrations determined by the present method differed from theory by <7 % in the phantom and were in agreement with data from the literature for the healthy controls. Using these normalized metabolic values, it was possible to demonstrate in the patient with brain glioma, metabolic abnormalities in normalized N-acetyl aspartate, choline and creatine levels; illustrating the potential for direct use of this technique in clinical studies. Conclusion The proposed combination of sequences provides a robust ρ map that can be used to normalize metabolic maps in clinical MRSI studies.
      PubDate: 2014-06-08
  • Measuring short-term liver metabolism non-invasively: postprandial and
           post-exercise 1H and
           31P MR spectroscopy
    • Abstract: Object The objective of this study was to determine the effects of a standardized fat rich meal and subsequent exercise on liver fat content by 1H MRS and on liver adenosine triphosphate (ATP) content by 31P MRS in healthy subjects. Materials and methods Hepatic 1H and proton decoupled 31P MRS were performed on nine healthy subjects on a clinical 3.0 T MR imager three times during a day: after (1) an overnight fast, (2) a following standardized fat rich meal and (3) a subsequent exercise session. Blood parameters were followed during the day to serve as a reference to MRS. Results Liver fat content increased gradually over the day (p = 0.0001) with an overall increase of 30 %. Also γ-NTP changed significantly over the day (p = 0.005). γ-NTP/tP decreased by 9 % (p = 0.019, post hoc) from the postprandial to the post-exercise state. Conclusion Our study shows that in vivo MRS can depict short lived physiological changes; entering of fat into liver cells and consumption of ATP during exercise can be measured non-invasively in healthy subjects. The physiological state may have an impact on fat and energy metabolite levels. Hepatic 1H and 31P MRS studies should be performed under standardized conditions.
      PubDate: 2014-06-04
  • Hemi-spectrum substitution after water signal fitting (HESWAF): an
           improvement of the modulus post-processing of MR spectra
    • Abstract: Objective In a previous study, we have shown that modulus post-processing is a simple and efficient tool to both phase correct and frequency align magnetic resonance (MR) spectra automatically. Furthermore, this technique also eliminates sidebands and phase distortions. The advantages of the modulus technique have been illustrated in several applications to brain proton MR spectroscopy. Two possible drawbacks have also been pointed out. The first one is the theoretical decrease in signal-to-noise ratio (SNR) by a factor up to √2 when comparing the spectrum obtained after modulus versus conventional post-processing. The second pitfall results from the symmetrization of the spectrum induced by modulus post-processing, since any resonance or artifact located at the left of the water resonance is duplicated at the right of the water resonance, thus contaminating the region of the spectrum containing the resonances of interest. Herein, we propose a strategy in order to eliminate these two limitations. Materials and methods Concerning the SNR issue, two complementary approaches are presented here. The first is based on the application of modulus post-processing before spatial apodization, and the second consists in substituting the left half of the spectrum by the fit of the water resonance before applying modulus post-processing. The symmetrization induced by modulus post-processing then combines the right half of the original spectrum containing the resonances of interest with the left half of the water fit, free of noise and artifacts. Consequently, the SNR is improved when compared to modulus post-processing alone. As a bonus, any artifact or resonance present in the left half of the original spectrum is removed. This solves the second limitation. Results After validation of the technique on simulations, we demonstrated that this improvement of the modulus technique is significantly advantageous for both in vitro and in vivo applications. Conclusion By improving the SNR of the spectra and eliminating eventual contaminations, the new strategies proposed here confer an additional competitive advantage to the modulus post-processing technique.
      PubDate: 2014-06-03
  • Purely phase-encoded MRI of turbulent flow through a dysfunctional
           bileaflet mechanical heart valve
    • Abstract: Object We have used a purely phase-encoded magnetic resonance imaging (MRI) technique, single-point ramped imaging with T1 enhancement (SPRITE), to investigate the steady, turbulent flow dynamics through a bileaflet mechanical heart valve (BMHV). Materials and methods We have measured in vitro the turbulent diffusivity and velocity downstream of the valve in two configurations (fully opened and partially opened), which mimic normal and dysfunctional operation. Our constant-time implementation of the MRI measurement is unusually robust to fast turbulent flows, and to artefacts caused by the pyrolytic carbon construction of the valve. Results Turbulent diffusivity downstream of the normally functioning valve peaks at 1.05 × 10−6 m2/s, while the turbulent diffusivity is higher downstream of the dysfunctional valve (peaking at 3.15 × 10−6 m2/s) and is accompanied by a high-velocity fluid jet and re-circulating flow. The fluid jet is not along the centreline of the valve, as might be anticipated in conventional Doppler echocardiography measurements. Conclusion The nature of motion-sensitized SPRITE makes it unusually capable in turbulent flows and near to boundaries between different magnetic susceptibilities. These qualities have allowed us to compare the three-dimensional flow fields through normal and dysfunctional BMHVs.
      PubDate: 2014-06-01
  • Application of kt-BLAST acceleration to reduce cardiac MR imaging time in
           healthy and infarcted mice
    • Abstract: Object We evaluated the use of kt-broad-use linear acquisition speed-up technique (kt-BLAST) acceleration of mouse cardiac imaging in order to reduce scan times, thereby minimising physiological variation and improving animal welfare. Materials and methods Conventional cine cardiac MRI data acquired from healthy mice (n = 9) were subsampled to simulate kt-BLAST acceleration. Cardiological indices (left ventricular volume, ejection fraction and mass) were determined as a function of acceleration factor. kt-BLAST threefold undersampling was implemented on the scanner and applied to a second group of mice (n = 6 healthy plus 6 with myocardial infarct), being compared with standard cine imaging (3 signal averages) and cine imaging with one signal average. Results In the simulations, sufficient accuracy was achieved for undersampling factors up to three. Cardiological indices determined from the implemented kt-BLAST scanning showed no significant differences compared with the values determined from the standard sequence, and neither did indices derived from the cine scan with only one signal average despite its lower signal-to-noise ratio. Both techniques were applied successfully in the infarcted hearts. Conclusion For cardiac imaging of mice, threefold undersampling of kt-space, or a similar reduction in the number of signal averages, are both feasible with subsequent reduction in imaging time.
      PubDate: 2014-06-01
  • Longitudinal myocardial peak velocities using high temporal resolution
           phase-contrast and simple averaging are comparable to tissue Doppler
    • Abstract: Object Phase contrast imaging is widely used to measure blood velocity. However tissue Doppler imaging (TDI) echocardiography is the reference for myocardial velocity assessment. This study aims at validating the ability of phase contrast (PC) sequences to correctly assess myocardial velocities and to compare these velocities to TDI. The phase contrast sequence was performed with breath-hold parameters and with parameters tuned to increase temporal resolution in free breathing. Materials and methods Left and Right auriculo-ventricular annuluses longitudinal velocities were recorded on six healthy volunteers with different temporal resolutions (TDI: 5 ms, breath-hold PC: 94 ms and free-breathing PC: 19 ms). Free-breathing PC was obtained by averaging of three excitations. Amplitudes of four standard echocardiographic and clinically relevant myocardial longitudinal velocity waves were compared: Early filling and auricular, systolic and isovolumic contractions. Results Isovolumic contraction waves were only visible with free-breathing PC and TDI. The differences with the reference TDI wave velocities were lower (p = 0.02) for free-breathing PC (19.2 ± 2.6 %) than for breath-hold PC (28.1 ± 2.9 %). These differences for free-breathing PC were close to (p = 0.21) the coefficient of variation of the measurements provided by TDI (14.8 ± 1.2 %). Conclusion Myocardial longitudinal peak velocities can be assessed with a PC sequence tuned to optimize temporal resolution.
      PubDate: 2014-06-01
  • Fetal blood flow velocimetry by phase-contrast MRI using a new triggering
           method and comparison with Doppler ultrasound in a sheep model: a pilot
    • Abstract: Object We present the first study demonstrating the feasibility of antenatal blood flow velocimetry performing ECG triggered phase-contrast (PC)-MRI in the fetal aorta by using a newly developed Doppler ultrasound trigger. Materials and methods Five pregnant sheep carrying singleton fetuses (gestational age 121 days) were anesthetized to undergo fetal 2D PC-MRI in the fetal descending aorta (1.5 T) using a newly developed MR-compatible Doppler ultrasound trigger for fetal cardiac triggering. Inter-operator variability was assessed for PC-MR measurements and reproducibility was tested by repeated scans in one fetus. Inter-modality comparison was performed by Doppler ultrasound velocimetry. Results Fetal cardiac triggering was possible in all examinations. PC-MR velocimetry revealed a mean inter-operator variability of 3 ± 5 %. Average peak systolic flow velocities of 62.5 ± 4.4 cm/s were in good agreement with Doppler ultrasound measurements of 62.0 ± 9.2 cm/s (p (Lord’s U test) ≫ 0.05). Conclusion Fetal PC-MR velocimetry was successfully performed using the newly developed MR-compatible Doppler ultrasound trigger for intrauterine fetal cardiac triggering, demonstrating high inter-operator and inter-modality agreement. This new method has the high potential for alternative assessment of hemodynamic decompensation of the fetal circulation.
      PubDate: 2014-06-01
  • Conversion rate of        class="a-plus-plus">para-hydrogen to        class="a-plus-plus">ortho-hydrogen by oxygen:
           implications for PHIP gas storage and utilization
    • Abstract: Object To determine the storability of para-hydrogen before reestablishment of the room temperature thermal equilibrium mixture. Materials and methods Para-hydrogen was produced at near 100 % purity and mixed with different oxygen quantities to determine the rate of conversion to the thermal equilibrium mixture of 75: 25 % (ortho: para) by detecting the ortho-hydrogen 1H nuclear magnetic resonance using a 9.4 T imager. Results The para-hydrogen to ortho-hydrogen velocity constant, k, near room temperature (292 K) was determined to be 8.27 ± 1.30 L/mol·min−1. This value was calculated utilizing four different oxygen fractions. Conclusions Para-hydrogen conversion to ortho-hydrogen by oxygen can be minimized for long term storage with judicious removal of oxygen contamination. Prior calculated velocity rates were confirmed demonstrating a dependence on only the oxygen concentration.
      PubDate: 2014-06-01
  • Increasing spatial resolution of 3T MRI scanning improves reproducibility
           of carotid arterial wall dimension measurements
    • Abstract: Objective To improve carotid 3T magnetic resonance imaging (MRI) dimension measurements in patients with overt atherosclerotic carotid artery disease. Materials and methods In 31 patients with advanced atherosclerotic carotid artery disease, two high resolution (0.25 × 0.25 mm2; HR) and two routinely used low resolution (0.50 × 0.50 mm2; LR) carotid 3T MRI scans were performed within 1 month. After manual delineation of carotid wall contours in a dedicated image analyses program in eight slices covering the atherosclerotic plaque, image reproducibility, as well as the within-reader and between-reader variability were determined. Results We found significantly higher intraclass correlation coefficients for total wall volume, mean wall area and mean wall thickness for the HR measurements (all p < 0.05). We found a significant lower signal-to-noise and contrast-to-noise ratio for the HR compared to the LR measurements. The carotid arterial wall dimension measurements of all parameters were significantly lower for the HR compared to the LR measurements. No significant differences were observed between the within-reader and between-reader reproducibility for HR versus LR measurements. Conclusion Increasing the in-plane resolution improves the reproducibility of 3T MRI carotid arterial wall dimension measurements. The use of HR imaging will contribute to a reduced sample size needed in intervention trials using MRI scanning of the carotid artery as surrogate marker for atherosclerosis progression.
      PubDate: 2014-06-01
  • Acoustic noise reduction in pseudo-continuous arterial spin labeling
    • Abstract: Object While pseudo-continuous arterial spin labeling (pCASL) is a promising imaging technique to visualize cerebral blood flow, it is also (acoustically) very loud during labeling. In this paper, we reduced the labeling loudness on our scanner by increasing the interval between the RF pulses from the literature standard of 1.0 ms. We also propose recommendations to reduce the loudness on scanners of the same type at other sites. Materials and methods First, the sound pressure level (SPL) was both simulated and measured as a function of the labeling interval (1.0–1.8 ms) and longitudinal position in the scanner (−10 to +10 cm, relative to isocenter). Subsequently, we selected the labeling interval with the lowest overall SPL for the "SPL-optimized" pCASL sequence. Nine volunteers were scanned to compare raw signal intensity, temporal signal-to-noise ratio (tSNR) and labeling efficiency between the SPL-optimized and the standard PCASL sequence. Results Sound pressure level measurements on our scanner showed that loudness was reduced by 6.5 dB at the approximate location of the ear by adjusting the labeling interval to 1.4 ms. Furthermore, image quality was not affected, since no significant differences in signal intensity, tSNR and labeling efficiency were observed. Conclusion By increasing the pCASL labeling interval, acoustic noise in the pCASL sequence was reduced with 6.5 dB, while image quality was preserved.
      PubDate: 2014-06-01
  • Improved short tau inversion recovery (iSTIR) for increased tumor
           conspicuity in the abdomen
    • Abstract: Object To develop an improved short tau inversion recovery (iSTIR) technique with simultaneous suppression of fat, blood vessels and fluid to increase tumor conspicuity in the abdomen for cancer screening. Materials and methods An adiabatic spectrally selective inversion pulse was used for fat suppression to overcome the reduced signal to noise ratio associated with chemically non-selective inversion pulse of STIR. A motion-sensitizing driven equilibrium was used for blood vessel suppression and a dual-echo single-shot fast spin echo acquisition was used for fluid suppression. The technique was optimized on four normal subjects and later tested on five patients referred for metastatic tumor evaluation. Results A velocity encoding of 2 cm/s achieved effective blood suppression even in small vessels. Subtraction of two images (one with 60 ms and the other with 280 ms echo time) acquired in the same echo train achieved excellent fluid suppression (>70 % reduction). Simultaneous suppression of fat, blood vessels and fluid improved the tumor conspicuity compared to corresponding fat-suppressed (STIR) image. Conclusion This technique generated two complementary images from a single scan: one that is equivalent to a STIR image and the other that qualitatively resembles a diffusion-weighted image and may have potential for magnetic resonance imaging cancer screening.
      PubDate: 2014-06-01
  • Construction of an in vivo human spinal cord atlas based on
           high-resolution MR images at cervical and thoracic levels: preliminary
    • Abstract: Object Our goal was to build a probabilistic atlas and anatomical template of the human cervical and thoracic spinal cord (SC) that could be used for segmentation algorithm improvement, parametric group studies, and enrichment of biomechanical modelling. Materials and methods High-resolution axial T2*-weighted images were acquired at 3T on 15 healthy volunteers using a multi-echo–gradient-echo sequence (1 slice per vertebral level from C1 to L2). After manual segmentation, linear and affine co-registrations were performed providing either inter-individual morphometric variability maps, or substructure probabilistic maps [CSF, white and grey matter (WM/GM)] and anatomical SC template. Results The larger inter-individual morphometric variations were observed at the thoraco-lumbar levels and in the posterior GM. Mean SC diameters were in agreement with the literature and higher than post-mortem measurements. A representative SC MR template was generated and values up to 90 and 100 % were observed on GM and WM-probability maps. Conclusion This work provides a probabilistic SC atlas and a template that could offer great potentialities for parametrical MRI analysis (DTI/MTR/fMRI) and group studies, similar to what has already been performed using a brain atlas. It also offers great perspective for biomechanical models usually based on post-mortem or generic data. Further work will consider integration into an automated SC segmentation pipeline.
      PubDate: 2014-06-01
  • Transparent thin shield for radio frequency transmit coils
    • Abstract: Objective To identify a shielding material compatible with optical head-motion tracking for prospective motion correction and which minimizes radio frequency (RF) radiation losses at 7 T without sacrificing line-of-sight to an imaging target. Materials and methods We evaluated a polyamide mesh coated with silver. The thickness of the coating was approximated from the composition ratio provided by the material vendor and validated by an estimate derived from electrical conductivity and light transmission measurements. The performance of the shield is compared to a split-copper shield in the context of a four-channel transmit-only loop array. Results The mesh contains less than a skin-depth of silver coating (300 MHz) and attenuates light by 15 %. Elements of the array vary less in the presence of the mesh shield as compared to the split-copper shield indicating that the array behaves more symmetrically with the mesh shield. No degradation of transmit efficiency was observed for the mesh as compared to the split-copper shield. Conclusion We present a shield compatible with future integration of camera-based motion-tracking systems. Based on transmit performance and eddy-current evaluations the mesh shield is appropriate for use at 7 T.
      PubDate: 2014-05-27
  • Volumetric velocity measurements in restricted geometries using spiral
           sampling: a phantom study
    • Abstract: Object The aim of this study was to evaluate the accuracy of maximum velocity measurements using volumetric phase-contrast imaging with spiral readouts in a stenotic flow phantom. Materials and methods In a phantom model, maximum velocity, flow, pressure gradient, and streamline visualizations were evaluated using volumetric phase-contrast magnetic resonance imaging (MRI) with velocity encoding in one (extending on current clinical practice) and three directions (for characterization of the flow field) using spiral readouts. Results of maximum velocity and pressure drop were compared to computational fluid dynamics (CFD) simulations, as well as corresponding low-echo-time (TE) Cartesian data. Flow was compared to 2D through-plane phase contrast (PC) upstream from the restriction. Results Results obtained with 3D through-plane PC as well as 4D PC at shortest TE using a spiral readout showed excellent agreements with the maximum velocity values obtained with CFD (<1 % for both methods), while larger deviations were seen using Cartesian readouts (−2.3 and 13 %, respectively). Peak pressure drop calculations from 3D through-plane PC and 4D PC spiral sequences were respectively 14 and 13 % overestimated compared to CFD. Conclusion Identification of the maximum velocity location, as well as the accurate velocity quantification can be obtained in stenotic regions using short-TE spiral volumetric PC imaging.
      PubDate: 2014-05-18
  • Fast and accurate localization of multiple RF markers for tracking in
           MRI-guided interventions
    • Abstract: Object A new method for 3D localization of N fiducial markers from 1D projections is presented and analysed. It applies to semi-active markers and active markers using a single receiver channel. Materials and methods The novel algorithm computes candidate points using peaks in three optimally selected projections and removes fictitious points by verifying detected peaks in additional projections. Computational complexity was significantly reduced by avoiding cluster analysis, while higher accuracy was achieved by using optimal projections and by applying Gaussian interpolation in peak detection. Computational time, accuracy and robustness were analysed through Monte Carlo simulations and experiments. The method was employed in a prototype MRI guided prostate biopsy system and used in preclinical experiments. Results The computational time for 6 markers was better than 2 ms, an improvement of up to 100 times, compared to the method by Flask et al. (J Magn Reson Imaging 14(5):617–627, 2001). Experimental maximum localization error was lower than 0.3 mm; standard deviation was 0.06 mm. Targeting error was about 1 mm. Tracking update rate was about 10 Hz. Conclusion The proposed method is particularly suitable in systems requiring any of the following: high frame rate, tracking of three or more markers, data filtering or interleaving.
      PubDate: 2014-05-07
  • Data quality in fMRI and simultaneous EEG–fMRI
    • Abstract: Object To evaluate functional magnetic resonance imaging (fMRI) and simultaneous electroencephalography (EEG)–fMRI data quality in an organization using several magnetic resonance imaging (MRI) systems. Materials and methods Functional magnetic resonance imaging measurements were carried out twice with a uniform gel phantom on five different MRI systems with field strengths of 1.5 and 3.0 T. Several image quality parameters were measured with automatic analysis software. For simultaneous EEG–fMRI, data quality was evaluated on 3.0 T systems, and the phantom results were compared to data on human volunteers. Results The fMRI quality parameters measured with different MRI systems were on an acceptable level. The presence of the EEG equipment caused superficial artifacts on the phantom image. The typical artifact depth was 15 mm, and no artifacts were observed in the brain area in the images of volunteers. Average signal-to-noise ratio (SNR) reduction in the phantom measurements was 15 %, a reduction of SNR similar to that observed in the human data. We also detected minor changes in the noise of the EEG signal during the phantom measurement. Conclusion The phantom proved valuable in the successful evaluation of the data quality of fMRI and EEG–fMRI. The results fell within acceptable limits. This study demonstrated a repeatable method to measure and follow up on the data quality of simultaneous EEG–fMRI.
      PubDate: 2014-04-26
  • Erratum to: Quantitative accuracy of attenuation correction in the Philips
           Ingenuity TF whole-body PET/MR system: a direct comparison with
           transmission-based attenuation correction
    • PubDate: 2014-04-20
  • Multi-parametric (ADC/PWI/T2-w) image fusion approach for accurate
           semi-automatic segmentation of tumorous regions in glioblastoma multiforme
    • Abstract: Object Glioblastoma multiforme (GBM) brain tumor is heterogeneous in nature, so its quantification depends on how to accurately segment different parts of the tumor, i.e. viable tumor, edema and necrosis. This procedure becomes more effective when metabolic and functional information, provided by physiological magnetic resonance (MR) imaging modalities, like diffusion-weighted-imaging (DWI) and perfusion-weighted-imaging (PWI), is incorporated with the anatomical magnetic resonance imaging (MRI). In this preliminary tumor quantification work, the idea is to characterize different regions of GBM tumors in an MRI-based semi-automatic multi-parametric approach to achieve more accurate characterization of pathogenic regions. Materials and methods For this purpose, three MR sequences, namely T2-weighted imaging (anatomical MR imaging), PWI and DWI of thirteen GBM patients, were acquired. To enhance the delineation of the boundaries of each pathogenic region (peri-tumoral edema, viable tumor and necrosis), the spatial fuzzy C-means algorithm is combined with the region growing method. Results The results show that exploiting the multi-parametric approach along with the proposed semi-automatic segmentation method can differentiate various tumorous regions with over 80 % sensitivity, specificity and dice score. Conclusion The proposed MRI-based multi-parametric segmentation approach has the potential to accurately segment tumorous regions, leading to an efficient design of the pre-surgical treatment planning.
      PubDate: 2014-04-02
  • Characterization of the impact to PET quantification and image quality of
           an anterior array surface coil for PET/MR imaging
    • Abstract: Object The aim of this study was to determine the impact to PET quantification, image quality and possible diagnostic impact of an anterior surface array used in a combined PET/MR imaging system. Materials and methods An extended oval phantom and 15 whole-body FDG PET/CT subjects were re-imaged for one bed position following placement of an anterior array coil at a clinically realistic position. The CT scan, used for PET attenuation correction, did not include the coil. Comparison, including liver SUVmean, was performed between the coil present and absent images using two methods of PET reconstruction. Due to the time delay between PET scans, a model was used to account for average physiologic time change of SUV. Results On phantom data, neglecting the coil caused a mean bias of −8.2 % for non-TOF/PSF reconstruction, and −7.3 % with TOF/PSF. On clinical data, the liver SUV neglecting the coil presence fell by −6.1 % (±6.5 %) for non-TOF/PSF reconstruction; respectively −5.2 % (±5.3 %) with TOF/PSF. All FDG-avid features seen with TOF/PSF were also seen with non-TOF/PSF reconstruction. Conclusion Neglecting coil attenuation for this anterior array coil results in a small but significant reduction in liver SUVmean but was not found to change the clinical interpretation of the PET images.
      PubDate: 2014-04-01
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