To implement magnetic resonance fingerprinting (MRF) on a permanent magnet 50 mT low-field system deployable as a future point-of-care (POC) unit and explore the quality of the parameter maps.
Materials and methods3D MRF was implemented on a custom-built Halbach array using a slab-selective spoiled steady-state free precession sequence with 3D Cartesian readout. Undersampled scans were acquired with different MRF flip angle patterns and reconstructed using matrix completion and matched to the simulated dictionary, taking excitation profile and coil ringing into account. MRF relaxation times were compared to that of inversion recovery (IR) and multi-echo spin echo (MESE) experiments in phantom and in vivo. Furthermore, B0 inhomogeneities were encoded in the MRF sequence using an alternating TE pattern, and the estimated map was used to correct for image distortions in the MRF images using a model-based reconstruction.
ResultsPhantom relaxation times measured with an optimized MRF sequence for low field were in better agreement with reference techniques than for a standard MRF sequence. In vivo muscle relaxation times measured with MRF were longer than those obtained with an IR sequence (T1: 182 ± 21.5 vs 168 ± 9.89 ms) and with an MESE sequence (T2: 69.8 ± 19.7 vs 46.1 ± 9.65 ms). In vivo lipid MRF relaxation times were also longer compared with IR (T1: 165 ± 15.1 ms vs 127 ± 8.28 ms) and with MESE (T2: 160 ± 15.0 ms vs 124 ± 4.27 ms). Integrated ΔB0 estimation and correction resulted in parameter maps with reduced distortions.
DiscussionIt is possible to measure volumetric relaxation times with MRF at 2.5 × 2.5 × 3.0 mm3 resolution in a 13 min scan time on a 50 mT permanent magnet system. The measured MRF relaxation times are longer compared to those measured with reference techniques, especially for T2. This discrepancy can potentially be addressed by hardware, reconstruction and sequence design, but long-term reproducibility needs to be further improved.
相似文献To determine T1 and T2 relaxation times of healthy pancreas parenchyma at 7 T using a multi-transmit system.
Materials and methodsTwenty-six healthy subjects were scanned with a 7 T MR system using eight parallel transceiver antennas, each with two additional receive loops. A Look-Locker sequence was used to obtain images for T1 determination, while T2 was obtained from spin-echo images and magnetic resonance spectroscopy measurements with different echo times. T1 and T2 times were calculated using a mono-exponential fit of the average magnitude signal from a region of interest in the pancreas and were tested for correlation with age.
ResultsThe age range of the included subjects was 21–72 years. Average T1 and T2 relaxation times in healthy pancreas were 896 ± 149 ms, and 26.7 ± 5.3 ms, respectively. No correlation with age was found.
ConclusionT1 and T2 relaxation times of the healthy pancreas were reported for 7 T, which can be used for image acquisition optimization. No significant correlations were found between age and T1 or T2 relaxation times of the pancreas. Considering their low standard deviation and no observable age dependence, these values may be used as a baseline to study potentially pancreatic tissue affected by disease.
相似文献In this study, we aimed to measure the apparent diffusion coefficients (ADCs) of major phosphorous metabolites in the human calf muscle at 7 T with a diffusion-weighted (DW)-STEAM sequence.
MethodsA DW-STEAM sequence with bipolar gradients was implemented at 7 T, and DW MR spectra were acquired in three orthogonal directions in the human calf muscle of six healthy volunteers (TE/TM/TR = 15 ms/750 ms/5 s) at three b-values (0, 800, and 1200 s/mm2). Frequency and phase alignments were applied prior to spectral averaging. Averaged DW MR spectra were analyzed with LCModel, and ADCs of 31P metabolites were estimated.
ResultsFour metabolites (phosphocreatine (PCr), adenosine triphosphate (ATP), inorganic phosphate (Pi) and glycerol phosphorylcholine (GPC)) were quantified at all b-values with mean CRLBs below 10%. The ADC values of PCr, ATP, Pi, and GPC were (0.24 ± 0.02, 0.15 ± 0.04, 0.43 ± 0.14, 0.40 ± 0.09) × 10–3 mm2/s, respectively.
ConclusionThe ADCs of four 31P metabolites were successfully measured in the human calf muscle at 7 T, among which those of ATP, Pi and GPC were reported for the first time in humans. This study paves the way to investigate 31P metabolite diffusion properties in health and disease on the clinical MR scanner.
相似文献To evaluate systolic flow-sensitive alternating inversion recovery (FAIR) during rest and exercise stress using 2RR (two cardiac cycles) or 1RR intervals between inversion pulse and imaging.
Materials and methods1RR and 2RR FAIR was implemented on a 3T scanner. Ten healthy subjects were scanned during rest and stress. Stress was performed using an in-bore ergometer. Heart rate, mean myocardial blood flow (MBF) and temporal signal-to-noise ratio (TSNR) were compared using paired t tests.
ResultsMean heart rate during stress was higher than rest for 1RR FAIR (85.8 ± 13.7 bpm vs 63.3 ± 11.1 bpm; p < 0.01) and 2RR FAIR (83.8 ± 14.2 bpm vs 63.1 ± 10.6 bpm; p < 0.01). Mean stress MBF was higher than rest for 1RR FAIR (2.97 ± 0.76 ml/g/min vs 1.43 ± 0.6 ml/g/min; p < 0.01) and 2RR FAIR (2.8 ± 0.96 ml/g/min vs 1.22 ± 0.59 ml/g/min; p < 0.01). Resting mean MBF was higher for 1RR FAIR than 2RR FAIR (p < 0.05), but not during stress. TSNR was lower for stress compared to rest for 1RR FAIR (4.52 ± 2.54 vs 10.12 ± 3.69; p < 0.01) and 2RR FAIR (7.36 ± 3.78 vs 12.41 ± 5.12; p < 0.01). 2RR FAIR TSNR was higher than 1RR FAIR for rest (p < 0.05) and stress (p < 0.001).
DiscussionWe have demonstrated feasibility of systolic FAIR in rest and exercise stress. 2RR delay systolic FAIR enables non-contrast perfusion assessment during stress with relatively high TSNR.
相似文献To refine a new technique to measure respiratory-resolved left ventricular end-diastolic volume (LVEDV) in mid-inspiration and mid-expiration using a respiratory self-gating technique and demonstrate clinical feasibility in patients.
Materials and methodsTen consecutive patients were imaged at 1.5 T during 10 min of free breathing using a 3D golden-angle radial trajectory. Two respiratory self-gating signals were extracted and compared: from the k-space center of all acquired spokes, and from a superior–inferior projection spoke repeated every 64 ms. Data were binned into end-diastole and two respiratory phases of 15% respiratory cycle duration in mid-inspiration and mid-expiration. LVED volume and septal–lateral diameter were measured from manual segmentation of the endocardial border.
ResultsRespiratory-induced variation in LVED size expressed as mid-inspiration relative to mid-expiration was, for volume, 1 ± 8% with k-space-based self-gating and 8 ± 2% with projection-based self-gating (P = 0.04), and for septal–lateral diameter, 2 ± 2% with k-space-based self-gating and 10 ± 1% with projection-based self-gating (P = 0.002).
DiscussionMeasuring respiratory variation in LVED size was possible in clinical patients with projection-based respiratory self-gating, and the measured respiratory variation was consistent with previous studies on healthy volunteers. Projection-based self-gating detected a higher variation in LVED volume and diameter during respiration, compared to k-space-based self-gating.
相似文献To provide respiratory motion correction for free-breathing myocardial T1 mapping using a pilot tone (PT) and a continuous golden-angle radial acquisition.
Materials and methodsDuring a 45 s prescan the PT is acquired together with a dynamic sagittal image covering multiple respiratory cycles. From these images, the respiratory heart motion in head-feet and anterior–posterior direction is estimated and two linear models are derived between the PT and heart motion. In the following scan through-plane motion is corrected prospectively with slice tracking based on the PT. In-plane motion is corrected for retrospectively. Our method was evaluated on a motion phantom and 11 healthy subjects.
ResultsNon-motion corrected measurements using a moving phantom showed T1 errors of 14 ± 4% (p < 0.05) compared to a reference measurement. The proposed motion correction approach reduced this error to 3 ± 4% (p < 0.05). In vivo the respiratory motion led to an overestimation of T1 values by 26 ± 31% compared to breathhold T1 maps, which was successfully corrected to an average difference of 3 ± 2% (p < 0.05) between our free-breathing approach and breathhold data.
DiscussionOur proposed PT-based motion correction approach allows for T1 mapping during free-breathing with the same accuracy as a corresponding breathhold T1 mapping scan.
相似文献Evaluating the impact of the Inversion Time (TI) on regional perfusion estimation in a pediatric cohort using Arterial Spin Labeling (ASL).
Materials and methodsPulsed ASL (PASL) was acquired at 3 T both at TI 1500 ms and 2020 ms from twelve MRI-negative patients (age range 9–17 years). A volume of interest (VOIs) and a voxel-wise approach were employed to evaluate subject-specific TI-dependent Cerebral Blood Flow (CBF) differences, and grey matter CBF Z-score differences. A visual evaluation was also performed.
ResultsCBF was higher for TI 1500 ms in the proximal territories of the arteries (PTAs) (e.g. insular cortex and basal ganglia — P < 0.01 and P < 0.05 from the VOI analysis, respectively), and for TI 2020 ms in the distal territories of the arteries (DTAs), including the watershed areas (e.g. posterior parietal and occipital cortex — P < 0.001 and P < 0.01 from the VOI analysis, respectively). Similar differences were also evident when analyzing patient-specific CBF Z-scores and at a visual inspection.
ConclusionsTI influences ASL perfusion estimates with a region-dependent effect. The presence of intraluminal arterial signal in PTAs and the longer arterial transit time in the DTAs (including watershed areas) may account for the TI-dependent differences. Watershed areas exhibiting a lower perfusion signal at short TIs (~ 1500 ms) should not be misinterpreted as focal hypoperfused areas.
相似文献To improve the precision of a free-breathing 3D saturation-recovery-based myocardial T1 mapping sequence using a post-processing 3D denoising technique.
MethodsA T1 phantom and 15 healthy subjects were scanned on a 1.5 T MRI scanner using 3D saturation-recovery single-shot acquisition (SASHA) for myocardial T1 mapping. A 3D denoising technique was applied to the native T1-weighted images before pixel-wise T1 fitting. The denoising technique imposes edge-preserving regularity and exploits the co-occurrence of 3D spatial gradients in the native T1-weighted images by incorporating a multi-contrast Beltrami regularization. Additionally, 2D modified Look-Locker inversion recovery (MOLLI) acquisitions were performed for comparison purposes. Accuracy and precision were measured in the myocardial septum of 2D MOLLI and 3D SASHA T1 maps and then compared. Furthermore, the accuracy and precision of the proposed approach were evaluated in a standardized phantom in comparison to an inversion-recovery spin-echo sequence (IRSE).
ResultsFor the phantom study, Bland–Altman plots showed good agreement in terms of accuracy between IRSE and 3D SASHA, both on non-denoised and denoised T1 maps (mean difference −1.4 ± 18.9 ms and −4.4 ± 21.2 ms, respectively), while 2D MOLLI generally underestimated the T1 values (69.4 ± 48.4 ms). For the in vivo study, there was a statistical difference between the precision measured on 2D MOLLI and on non-denoised 3D SASHA T1 maps (P = 0.005), while there was no statistical difference after denoising (P = 0.95).
ConclusionThe precision of 3D SASHA myocardial T1 mapping was substantially improved using a 3D Beltrami regularization based denoising technique and was similar to that of 2D MOLLI T1 mapping, while preserving the higher accuracy and whole-heart coverage of 3D SASHA.
相似文献To experimentally characterize the effectiveness of a gradient nonlinearity correction method in removing ADC bias for different motion-compensated diffusion encoding waveforms.
MethodsThe diffusion encoding waveforms used were the standard monopolar Stejskal–Tanner pulsed gradient spin echo (pgse) waveform, the symmetric bipolar velocity-compensated waveform (sym-vc), the asymmetric bipolar velocity-compensated waveform (asym-vc) and the asymmetric bipolar partial velocity-compensated waveform (asym-pvc). The effectiveness of the gradient nonlinearity correction method using the spherical harmonic expansion of the gradient coil field was tested with the aforementioned waveforms in a phantom and in four healthy subjects.
ResultsThe gradient nonlinearity correction method reduced the ADC bias in the phantom experiments for all used waveforms. The range of the ADC values over a distance of ± 67.2 mm from isocenter reduced from 1.29 × 10–4 to 0.32 × 10–4 mm2/s for pgse, 1.04 × 10–4 to 0.22 × 10–4 mm2/s for sym-vc, 1.22 × 10–4 to 0.24 × 10–4 mm2/s for asym-vc and 1.07 × 10–4 to 0.11 × 10–4 mm2/s for asym-pvc. The in vivo results showed that ADC overestimation due to motion or bright vessels can be increased even further by the gradient nonlinearity correction.
ConclusionThe investigated gradient nonlinearity correction method can be used effectively with various motion-compensated diffusion encoding waveforms. In coronal liver DWI, ADC errors caused by motion and residual vessel signal can be increased even further by the gradient nonlinearity correction.
相似文献To provide a basis for the selection of suitable emulsifiers in oil-in-water emulsions used as tissue analogs for MRI experiments. Three different emulsifiers were investigated with regard to their ability to stabilize tissue-like oil-in-water emulsions. Furthermore, MR signal properties of the emulsifiers themselves and influences on relaxation times and ADC values of the aqueous phase were investigated.
Materials and methodsPolysorbate 60, sodium dodecyl sulfate (SDS) and soy lecithin were used as emulsifiers. MR characteristics of emulsifiers were assessed in aqueous solutions and their function as a stabilizer was examined in oil-in-water emulsions of varying fat content (10, 20, 30, 40, 50%). Stability and homogeneity of the oil-in-water emulsions were evaluated with a delay of 3 h and 9 h after preparation using T1 mapping and visual control. Signal properties of the emulsifiers were investigated by 1H-MRS in aqueous emulsifier solutions. Relaxometry and diffusion weighted MRI (DWI) were performed to investigate the effect of various emulsifier concentrations on relaxation times (T1 and T2) and ADC values of aqueous solutions.
ResultsEmulsions stabilized by polysorbate 60 or soy lecithin were stable and homogeneous across all tested fat fractions. In contrast, emulsions with SDS showed a significantly lower stability and homogeneity. Recorded T1 maps revealed marked creaming of oil droplets in almost all of the emulsions with SDS. The spectral analysis showed several additional signals for polysorbate and SDS. However, lecithin remained invisible in 1H-MRS. Relaxometry and DWI revealed different influences of the emulsifiers on water: Polysorbate and SDS showed only minor effects on relaxation times and ADC values of aqueous solutions, whereas lecithin showed a strong decrease in both relaxation times (r1,lecithin = 0.11 wt.%−1 s−1, r2,lecithin = 0.57 wt.%−1 s−1) and ADC value (Δ(ADC)lecithin = − 0.18 × 10–3 mm2/s⋅wt.%) with increasing concentration.
ConclusionLecithin is suggested as the preferred emulsifier of oil-in-water emulsions in MRI as it shows a high stabilizing ability and remains invisible in MRI experiments. In addition, lecithin is suitable as an alternative means of adjusting relaxation times and ADC values of water.
相似文献It is well known that the use of shift reagents (SRs) in nuclear magnetic resonance (NMR) studies is substantially limited by an intact blood–brain barrier (BBB). The current study aims to develop a method enabling chemical shift imaging in the living rat brain under physiological conditions using an SR, Tm[DOTP]5−.
Materials and methodsHyperosmotic mannitol bolus injection followed by 60 min infusion of a Tm[DOTP]5− containing solution was administered via a catheter inserted into an internal carotid artery. We monitored the homeostasis of physiological parameters, and we measured the thulium content in brain tissue post mortem using total reflection fluorescence spectroscopy (T-XRF). The alterations of the 23Na resonance spectrum were followed in a 9.4T small animal scanner.
ResultsBased on the T-XRF measurements, the thulium concentration was estimated at 2.3 ± 1.8 mM in the brain interstitial space. Spectroscopic imaging showed a split of the 23Na resonance peak which became visible 20 min after starting the infusion. Chemical shift imaging revealed a significant decrease of the initial intensity level to 0.915 ± 0.058 at the end of infusion.
ConclusionOur novel protocol showed bulk accumulation of Tm[DOTP]5− thus enabling separation of the extra-/intracellular 23Na signal components in the living rat brain while maintaining physiological homeostasis.
相似文献To examine the feasibility of human cardiac MR (CMR) at 14.0 T using high-density radiofrequency (RF) dipole transceiver arrays in conjunction with static and dynamic parallel transmission (pTx).
Materials and methodsRF arrays comprised of self-grounded bow-tie (SGBT) antennas, bow-tie (BT) antennas, or fractionated dipole (FD) antennas were used in this simulation study. Static and dynamic pTx were applied to enhance transmission field (B1+) uniformity and efficiency in the heart of the human voxel model. B1+ distribution and maximum specific absorption rate averaged over 10 g tissue (SAR10g) were examined at 7.0 T and 14.0 T.
ResultsAt 14.0 T static pTx revealed a minimum B1+ROI efficiency of 0.91 μT/√kW (SGBT), 0.73 μT/√kW (BT), and 0.56 μT/√kW (FD) and maximum SAR10g of 4.24 W/kg, 1.45 W/kg, and 2.04 W/kg. Dynamic pTx with 8 kT points indicate a balance between B1+ROI homogeneity (coefficient of variation < 14%) and efficiency (minimum B1+ROI > 1.11 µT/√kW) at 14.0 T with a maximum SAR10g < 5.25 W/kg.
DiscussionMRI of the human heart at 14.0 T is feasible from an electrodynamic and theoretical standpoint, provided that multi-channel high-density antennas are arranged accordingly. These findings provide a technical foundation for further explorations into CMR at 14.0 T.
相似文献19F MRI requires biocompatible and non-toxic soluble contrast agents with high fluorine content and with suitable 19F relaxation times. Probes based on a DOTP chelate with 12 magnetically equivalent fluorine atoms (DOTP-tfe) and a lanthanide(III) ion shortening the relaxation times were prepared and tested.
MethodsComplexes of DOTP-tfe with trivalent paramagnetic Ce, Dy, Ho, Tm, and Yb ions were synthetized and characterized. 19F relaxation times were determined and compared to those of the La complex and of the empty ligand. In vitro and in vivo 19F MRI was performed at 4.7 T.
Results19F relaxation times strongly depended on the chelated lanthanide(III) ion. T1 ranged from 6.5 to 287 ms, T2 from 3.9 to 124.4 ms, and T2* from 1.1 to 3.1 ms. All complexes in combination with optimized sequences provided sufficient signal in vitro under conditions mimicking experiments in vivo (concentrations 1.25 mM, 15-min scanning time). As a proof of concept, two contrast agents were injected into the rat muscle; 19F MRI in vivo confirmed the in vivo applicability of the probe.
ConclusionDOTP-based 19F probes showed suitable properties for in vitro and in vivo visualization and biological applications. The lanthanide(III) ions enabled us to shorten the relaxation times and to trim the probes according to the actual needs. Similar to the clinically approved Gd3+ chelates, this customized probe design ensures consistent biochemical properties and similar safety profiles.
相似文献Fluorine MR would benefit greatly from enhancements in signal-to-noise ratio (SNR). This study examines the sensitivity gain of 19F MR that can be practically achieved when moving from 9.4 to 21.1 T.
Materials and methodsWe studied perfluoro-15-crown-5-ether (PFCE) at both field strengths (B0), as a pure compound, in the form of nanoparticles (NP) as employed to study inflammation in vivo, as well as in inflamed tissue. Brains, lymph nodes (LNs) and spleens were obtained from mice with experimental autoimmune encephalomyelitis (EAE) that had been administered PFCE NPs. All samples were measured at both B0 with 2D-RARE and 2D-FLASH using 19F volume radiofrequency resonators together. T1 and T2 of PFCE were measured at both B0 strengths.
ResultsCompared to 9.4 T, an SNR gain of > 3 was observed for pure PFCE and > 2 for PFCE NPs at 21.1 T using 2D-FLASH. A dependency of 19F T1 and T2 relaxation on B0 was demonstrated. High spatially resolved 19F MRI of EAE brains and LNs at 21.1 T revealed signals not seen at 9.4 T.
DiscussionEnhanced SNR and T1 shortening indicate the potential benefit of in vivo 19F MR at higher B0 to study inflammatory processes with greater detail.
相似文献MRI of excised hearts at ultra-high field strengths (\({\mathrm{B}}_{0}\)≥7 T) can provide high-resolution, high-fidelity ground truth data for biomedical studies, imaging science, and artificial intelligence. In this study, we demonstrate the capabilities of a custom-built, multiple-element transceiver array customized for high-resolution imaging of excised hearts.
MethodA dedicated 16-element transceiver loop array was implemented for operation in parallel transmit (pTx) mode (8Tx/16Rx) of a clinical whole-body 7 T MRI system. The initial adjustment of the array was performed using full-wave 3D-electromagnetic simulation with subsequent final fine-tuning on the bench.
ResultsWe report the results of testing the implemented array in tissue-mimicking liquid phantoms and excised porcine hearts. The array demonstrated high efficiency of parallel transmits characteristics enabling efficient pTX-based B1+-shimming.
ConclusionThe receive sensitivity and parallel imaging capability of the dedicated coil were superior to that of a commercial 1Tx/32Rx head coil in both SNR and T2*-mapping. The array was successfully tested to acquire ultra-high-resolution (0.1 × 0.1 × 0.8 mm voxel) images of post-infarction scar tissue. High-resolution (isotropic 1.6 mm3 voxel) diffusion tensor imaging-based tractography provided high-resolution information about normal myocardial fiber orientation.
相似文献Oxygen-loaded nanobubbles have shown potential for reducing tumour hypoxia and improving treatment outcomes, however, it remains difficult to noninvasively measure the changes in partial pressure of oxygen (PO2) in vivo. The linear relationship between PO2 and longitudinal relaxation rate (R1) has been used to noninvasively infer PO2 in vitreous and cerebrospinal fluid, and therefore, this experiment aimed to investigate whether R1 is a suitable measurement to study oxygen delivery from such oxygen carriers.
MethodsT1 mapping was used to measure R1 in phantoms containing nanobubbles with varied PO2 to measure the relaxivity of oxygen (r1Ox) in the phantoms at 7 and 3 T. These measurements were used to estimate the limit of detection (LOD) in two experimental settings: preclinical 7 T and clinical 3 T MRI.
ResultsThe r1Ox in the nanobubble solution was 0.00057 and 0.000235 s−1/mmHg, corresponding to a LOD of 111 and 103 mmHg with 95% confidence at 7 and 3 T, respectively.
ConclusionThis suggests that T1 mapping could provide a noninvasive method of measuring a > 100 mmHg oxygen delivery from therapeutic nanobubbles.
相似文献Brain atrophy has the potential to become a biomarker for severity of radiation-induced side-effects. Particularly brain tumour patients can show great MRI signal changes over time caused by e.g. oedema, tumour progress or necrosis. The goal of this study was to investigate if such changes affect the segmentation accuracy of normal appearing brain and thus influence longitudinal volumetric measurements.
Materials and methodsT1-weighted MR images of 52 glioblastoma patients with unilateral tumours acquired before and three months after the end of radio(chemo)therapy were analysed. GM and WM volumes in the contralateral hemisphere were compared between segmenting the whole brain (full) and the contralateral hemisphere only (cl) with SPM and FSL. Relative GM and WM volumes were compared using paired t tests and correlated with the corresponding mean dose in GM and WM, respectively.
ResultsMean GM atrophy was significantly higher for full segmentation compared to cl segmentation when using SPM (mean ± std: ΔVGM,full = − 3.1% ± 3.7%, ΔVGM,cl = − 1.6% ± 2.7%; p < 0.001, d = 0.62). GM atrophy was significantly correlated with the mean GM dose with the SPM cl segmentation (r = − 0.4, p = 0.004), FSL full segmentation (r = − 0.4, p = 0.004) and FSL cl segmentation (r = -0.35, p = 0.012) but not with the SPM full segmentation (r = − 0.23, p = 0.1).
ConclusionsFor accurate normal tissue volume measurements in brain tumour patients using SPM, abnormal tissue needs to be masked prior to segmentation, however, this is not necessary when using FSL.
相似文献To evaluate the feasibility of in-vivo quantitative susceptibility mapping (QSM) of the human kidney.
MethodsAn axial single-breath-hold 3D multi-echo sequence (acquisition time 33 s) was completed on a 3 T-MRI-scanner (Magnetom Prisma, Siemens Healthineers, Erlangen, Germany) in 19 healthy volunteers. Graph-cut-based unwrapping combined with the T2*-IDEAL approach was performed to remove the chemical shift of fat and to quantify QSM of the upper abdomen. Mean susceptibility values of the entire, renal cortex and medulla in both kidneys and the liver were determined and compared. Five subjects were measured twice to examine the reproducibility. One patient with severe renal fibrosis was included in the study to evaluate the potential clinical relevance of QSM.
ResultsQSM was successful in 17 volunteers and the patient with renal fibrosis. Anatomical structures in the abdomen were clearly distinguishable by QSM and the susceptibility values obtained in the liver were comparable to those found in the literature. The results showed a good reproducibility. Besides, the mean renal QSM values obtained in healthy volunteers (0.04?±?0.07 ppm for the right and ? 0.06?±?0.19 ppm for the left kidney) were substantially higher than that measured in the investigated fibrotic kidney (? 0.43?±?? 0.02 ppm).
ConclusionQSM of the human kidney could be a promising approach for the assessment of information about microscopic renal tissue structure. Therefore, it might further improve functional renal MR imaging.
相似文献