Selective 3D ultrashort TE imaging: comparison of “dual-echo” acquisition and magnetization preparation for improving short-<Emphasis Type="Italic">T</Emphasis><Subscript>2</Subscript> contrast

Objective The objective of this study was to compare two different schemes for long-T ₂ component suppression in ultrashort echo-time (UTE) imaging. The aim was to increase conspicuity of short-T ₂ components accessible by the UTE technique. Materials and methods A “dual-echo” and a magnetization-preparation approach for long-T ₂ and fat suppression were implemented on clinical scanners. Both techniques were compared in 3D UTE exams on healthy volunteers regarding short-T ₂ Signal-to-noise ratio (SNR), long-T ₂ suppression quality, and scan efficiency. A quantitative SNR evaluation was performed using ankle scans of six volunteers. T ₂ suppression profiles were simulated for both approaches to facilitate interpretation of the observations. Results At 1.5 T, both techniques perform equally well in suppressing long-T ₂ components and fat. Magnetization preparation requires more shimming effort due to the use of narrow-band pulses, while the “dual-echo” technique requires a post-processing step to form a subtraction image. For scans with a short repetition time (TR), the “dual-echo” approach is much faster than the magnetization preparation, which depends on slow T ₁ recovery between preparation steps. The SNR comparison shows slightly higher short-T ₂ SNR for the “dual-echo” approach. At 3.0 T, magnetization preparation becomes more challenging due to stronger off-resonance effects. Conclusion Both techniques are well suited for long-T ₂ suppression and offer comparable short-T ₂ SNR. However, the “dual-echo” approach has strong advantages in terms of scan efficiency and off-resonance behavior.     

Fast three-dimensional sodium imaging of human brain

A three-dimensional sodium imaging technique with a minimum echo time of 0.9 ms is described in a 2.0 Tesla whole-body system. The relaxation behaviour in vivo of sodium was analysed: a lastT ₂ ^* relaxation component between 1.2 and 1.6 ms and a slowT ₂ ^* relaxation component between 7.1 ms and 8.4 ms were quantified in brain tissue of three volunteers. Three-dimensional sodium images of the human brain were acquired in 8.5 min with a resolution of 4.7 × 4.7 × 10 mm (0.2 cc voxel size) and a signal-to-noise ratio of 20 in brain tissue and 30 in cerebrospinal fluid.     

3D magnetic resonance fingerprinting on a low-field 50 mT point-of-care system prototype: evaluation of muscle and lipid relaxation time mapping and comparison with standard techniques

Objective

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 methods

3D 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.

Results

Phantom 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.

Discussion

It 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.

     

Volume and contrast development in the Rose Bengal model of cerebral infarction

The development of the Rose Bengal model of cerebral infarction in the rat is monitored using rapid NMR imaging techniques. The lesion volume,T ₁,T ₂, and the apparent diffusion coefficient (ADC) are measured in the time interval between 24 and 168 h postinduction. VolumetricT ₁-weighted 3D imaging of the lesions produced by this model is shown to have a standard error of about 5% over the first 3 days postinduction, rising to about 15% at 1 week. Both theT ₁ andT ₂ contrasts are found to be more durable than those in ADC and are, hence, more suitable for volumetric monitoring over this time period. An elevation in ADC is also observed in tissue outside the lesion and this is interpreted as being caused by the transport of edema away from the lesion.     

Human rapid acquisition with relaxation enhancement imaging at 8 T without specific absorption rate violation

A standard fast imaging sequence, rapid acquisition with relaxation enhancement (RARE), has been applied to human magnetic resonance at 8 T. RARE is known for its speed, good contrast and high RF power content. HighlyT ₂ weighted images, the hallmark of RARE imaging, were acquired from the human brain. It is demonstrated that whileT ₂ values may be reduced at 8 T, high quality RARE images could still be acquired at this field strength. Most importantly however, it is demonstrated that RARE images could be acquired without violating specific absorption rate (SAR) guidelines. Since it is well known thatT ₂ weighted images are of significant value in clinical diagnosis, the implementation of RARE at this field strength will provide ultra high field MRI (UHFMRI) with a valuable imaging protocol at this field strength without exceeding SAR limitations.     

Evaluation of the pulmonary vasculature with three-dimensional magnetic resonance imaging techniques

Cardiac and respiratory motion during the long acquisition times required in 3d magnetic resonance imaging (MRI) can lead to excessive image degradation and consequently poor diagnosis and interpretation in the thoracic region. This paper addresses the issue of obtaining good image quality with 3d gradient echo (GE) imaging in the study of the pulmonary vascular system and its diseases. To study the pulmonary vascular system two approaches have been considered. First, a proton density/inflow weighted scan consisting of a syncopated 3d FLASH acquisition is used to provide a 3d pulmonary angiogram. Secondly, aT ₁ weighted scan using 3d IR-FLASH (inversion recovery FLASH) helps in determining the presence of pulmonary emboli. Multiple acquisitions and rectangular field of view are utilized to pseudogate to the respiratory period in order to reduce motion artifacts while keeping reasonable imaging times. Technical aspects on data collection during the approach to equilibrium and acquisition strategies in the presence of thoracic motion and its impact on vessel resolution are addressed. The method has proven successful for imaging volunteers and, more recently, in obtaining useful clinical information.     

Three-dimensional black-blood multi-contrast carotid imaging using compressed sensing: a repeatability study

Objective

The purpose of this work is to evaluate the repeatability of a compressed sensing (CS) accelerated multi-contrast carotid protocol at 3 T.

Materials and methods

Twelve volunteers and eight patients with carotid disease were scanned on a 3 T MRI scanner using a CS accelerated 3-D black-blood multi-contrast protocol which comprises T ₁w, T ₂w and PDw without CS, and with a CS factor of 1.5 and 2.0. The volunteers were scanned twice, the lumen/wall area and wall thickness were measured for each scan. Eight patients were scanned once, the inter/intra-observer reproducibility of the measurements was calculated.

Results

In the repeated volunteer scans, the interclass correlation coefficient (ICC) for the wall area measurement using a CS factor of 1.5 in PDw, T ₁w and T ₂w were 0.95, 0.81, and 0.97, respectively. The ICC for lumen area measurement using a CS factor of 1.5 in PDw, T ₁w and T ₂w were 0.96, 0.92, and 0.96, respectively. In patients, the ICC for inter/intra-observer measurements of lumen/wall area, and wall thickness were all above 0.81 in all sequences.

Conclusion

The results show a CS accelerated 3-D black-blood multi-contrast protocol is a robust and reproducible method for carotid imaging. Future protocol design could use CS to reduce the scanning time.

     

Dynamic MRI of swallowing: real-time volumetric imaging at 12 frames per second at 3 T

Objective

Dysphagia or difficulty in swallowing is a potentially hazardous clinical problem that needs regular monitoring. Real-time 2D MRI of swallowing is a promising radiation-free alternative to the current clinical standard: videofluoroscopy. However, aspiration may be missed if it occurs outside this single imaged slice. We therefore aimed to image swallowing in 3D real time at 12 frames per second (fps).

Materials and methods

At 3 T, three 3D real-time MRI acquisition approaches were compared to the 2D acquisition: an aligned stack-of-stars (SOS), and a rotated SOS with a golden-angle increment and with a tiny golden-angle increment. The optimal 3D acquisition was determined by computer simulations and phantom scans. Subsequently, five healthy volunteers were scanned and swallowing parameters were measured.

Results

Although the rotated SOS approaches resulted in better image quality in simulations, in practice, the aligned SOS performed best due to the limited number of slices. The four swallowing phases could be distinguished in 3D real-time MRI, even though the spatial blurring was stronger than in 2D. The swallowing parameters were similar between 2 and 3D.

Conclusion

At a spatial resolution of 2-by-2-by-6 mm with seven slices, swallowing can be imaged in 3D real time at a frame rate of 12 fps.

     

High-resolutation magnetic resonance imaging of the endolymphatic duct and sac

An anatomical study was carried out to determine the extent to which magnetic resonance imaging (MRI) could delineate inner ear structures. Anatomical preparations of human petrous temporal bone were examined and compared with the results of MRI in 20 healthy subjects to see whether the structures of the inner ear could be visualized. Imaging of the subjects was carried out in a 1.0-T MRI scanner (Siemens Magnetom Impact). Two stronglyT ₂*-weighted sequences were used: a 3D-PSIF sequence and a 3D-CISS sequence. The 3D data sets were postprocessed using a Maximum Intensity Projection (MIP) program. Our investigations show that it is possible to obtain accurate visualization of structures with a diameter of under 1 mm. In all 20 subjects it was possible to identify both the endolymphatic duct and the endolymphatic sac.     

Imaging lung function using rapid dynamic acquisition of <Emphasis Type="Italic">T</Emphasis><Subscript>1</Subscript>-maps during oxygen enhancement

This paper describes imaging of lung function with oxygen-enhanced MRI using dynamically acquired T ₁ parameter maps, which allows an accurate, quantitative assessment of time constants of T ₁-enhancement and therefore lung function. Eight healthy volunteers were examined on a 1.5-T whole-body scanner. Lung T ₁-maps based on an IR Snapshot FLASH technique (TE = 1.4 ms, TR = 3.5 ms, FA = 7 ^∘) were dynamically acquired from each subject. Without waiting for full relaxation between subsequent acquisition of T ₁-maps, one T ₁-map was acquired every 6.7 s. For comparison, all subjects underwent a standard pulmonary function test (PFT). Oxygen wash-in and wash-out time course curves of T ₁ relaxation rate (R ₁)-enhancement were obtained and time constants of oxygen wash-in (w _in) and wash-out (w _out) were calculated. Averaged over the whole right lung, the mean w _out was 43.90 ± 10.47 s and the mean (w _in) was 51.20 ± 15.53 s, thus about 17% higher in magnitude. Wash-in time constants correlated strongly with forced expired volume in one second in percentage of the vital capacity (FEV₁ % VC) and with maximum expiratory flow at 25% vital capacity (MEF25), whereas wash-out time constants showed only weak correlation. Using oxygen-enhanced rapid dynamic acquisition of T ₁-maps, time course curves of R ₁-enhancement can be obtained. With w _in and w _out two new parameters for assessing lung function are available. Therefore, the proposed method has the potential to provide regional information of pulmonary function in various lung diseases.     

Accelerated time-resolved 3D contrast-enhanced MR angiography at 3T: clinical experience in 31 patients

Purpose: To evaluate whether time-resolved 3D MR-angiography at 3T with a net acceleration factor of eight is applicable in clinical routine and to evaluate whether good image quality and a low artifact level can be achieved with a temporal update rate that allows for additional information on pathologies. Materials and methods: Thirty-one consecutive patients underwent time-resolved 3D contrast-enhanced MR-angiography on a 3T system. Imaging consisted of accelerated 3D gradient echo sequences combining parallel imaging with an acceleration factor of four, partial Fourier acquisition along phase and slice encoding direction, and twofold temporal acceleration using view sharing. Data volumes representing the arterial and venous contrast phases were independently evaluated by two experienced radiologists by grading of image quality and artifact level on a 0–3 scale. Results: Time-resolved MR-angiography was successfully performed in all subjects without the need for contrast agent bolus timing. Excellent arterial (average score = 2.65 ± 0.32) and good venous (average score = 2.56 ± 0.28) diagnostic image quality and little image degrading due to artifacts (average score = 2.20 ± 0.16) were confirmed by both independent readers (agreement in 65.2% of all evaluations). In 14 patients vascular pathologies were identified in the arterial phases. In eight examinations temporal resolution and depiction of contrast agent dynamics provided additional information about pathology. Discussion: Without the necessity for additional bolus timing, time-resolved 3D contrast-enhanced MR-angiography with imaging acceleration along both the spatial encoding direction and temporal domain revealed excellent diagnostic image quality in neurovascular and thoracic imaging. Despite the limited spatial resolution as compared to high-resolution imaging of the carotid artery bifurcation, the results demonstrate the applicability of contrast-enhanced MR-angiography in thoracic and abdominal MRA as well as cervical imaging with a temporal update rate allowing for additional information on pathologies. Future studies may include an evaluation of optimal trade-offs between spatial and temporal resolution, different acceleration factors and a comparison to the gold-standard for accuracy.     

A double-blind study to evaluate the efficacy and tolerability of a higher dose (0.3 mmol per kg bw) of gadodiamide injection as a contrast medium for MRI

Gadodiamide injection was administered intravenously to 48 patients with known or suspected central nervous system (CNS) lesions undergoing magnetic resonance imaging (MRI). Two parallel groups were examined to evaluate the efficacy and safety of single doses of 0.1 and 0.3mmol per kg bw. The principal measures of efficacy were diagnostic yield of MR images, the overall contrast enhancement and the contrast index (CI). Adverse events and serum bilirubin level were the main safety parameters. Nineteen patients in each dose group displayed contrast enhancement of the MR image (1.5 T Siemens Gyroscan MR unit;T ₁ TR/TE=560–650/15–25 ms;T ₂:TR/TE=2200–3100/22–90 ms). The CI increased by 47.3% in the 0.1 mmol/kg bw group and by 86.5% in the 0.3 mmol per kg bw group compared to the pre-contrast scan. Four patients in the 0.1 mmol per kg bw group and seven in the 0.3 mmol per kg bw group had their management changed by new information from the post-contrast scan and four patients in each dose group had their diagnosis altered following the post-contrast scan. Two patients in the 0.3 mmol per kg bw group experienced injection-associated discomfort. There were no other adverse events reported during the 24 h follow-up period. No clinically significant changes in serum bilirubin or other parameters of blood chemistry or haematology were observed. The study demonstrates that the safety profile of gadodiamide injection 0.3 mmol per kg bw is similar to that of 0.1 mmol per kg bw and that, at both doses, gadodiamide injection is a safe and effective contrast medium for use in patients undergoing MRI on the CNS. Slightly more patients had an improvement in diagnostic yield with the 0.3 mmol per kg bw dose and the CI was increased to a greater extent in this group, showing that when greater contrast is required the higher dose of gadodiamide injection may be considered. Further studies in selected patient groups, and with the use of different doses in the same patient are necessary to evaluate the diagnostic value of higher doses.     

Morphologic and functional changes in the unilateral 6-hydroxydopamine lesion rat model for Parkinson’s disease discerned with μSPECT and quantitative MRI

Object

In the present study, we aimed to evaluate the impact of neurodegeneration of the nigrostriatal tract in a rodent model of Parkinson’s disease on the different MR contrasts (T₂, T₁, CBF and CBV) measured in the striatum.

Material and methods

Animals were injected with 6-hydroxydopamine (6OHDA) in the substantia nigra resulting in massive loss of nigrostriatal neurons and hence dopamine depletion in the ipsilateral striatum. Using 7T MRI imaging, we have quantified T₂, T₁, CBF and CBV in the striata of 6OHDA and control rats. To validate the lesion size, behavioral testing, dopamine transporter μSPECT and tyrosine hydroxylase staining were performed.

Results

No significant differences were demonstrated in the absolute MRI values between 6OHDA animals and controls; however, 6OHDA animals showed significant striatal asymmetry for all MRI parameters in contrast to controls.

Conclusions

These PD-related asymmetry ratios might be the result of counteracting changes in both intact and affected striatum and allowed us to diagnose PD lesions. As lateralization is known to occur also in PD patients and might be expected in transgenic PD models as well, we propose that MR-derived asymmetry ratios in the striatum might be a useful tool for in vivo phenotyping of animal models of PD.     

High-resolution imaging of the excised porcine heart at a whole-body 7 T MRI system using an 8Tx/16Rx pTx coil

Introduction

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.

Method

A 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.

Results

We 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.

Conclusion

The 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.

     

Possibilities and limitations for high resolution small animal MRI on a clinical whole-body 3T scanner

Object

To investigate the potential of a clinical 3 T scanner to perform MRI of small rodents.

Materials and methods

Different dedicated small animal coils and several imaging sequences were evaluated to optimize image quality with respect to SNR, contrast and spatial resolution. As an application, optimal grey-white-matter contrast and resolution were investigated for rats. Furthermore, manganese-enhanced MRI was applied in mice with unilateral crush injury of the optic nerve to investigate coil performance on topographic mapping of the visual projection.

Results

Differences in SNR and CNR up to factor 3 and more were observed between the investigated coils. The best grey-white matter contrast was achieved with a high resolution 3D T ₂-weighted TSE (SPACE) sequence. Delineation of the retino-tectal projection and detection of defined visual pathway damage on the level of the optic nerve could be achieved by using a T ₁-weighted, 3D gradient echo sequence with isotropic resolution of (0.2?mm)³.

Conclusions

Experimental studies in small rodents requiring high spatial resolution can be performed by using a clinical 3 T scanner with appropriate dedicated coils.     

Parallel acquisition for effective density weighted imaging: PLANED imaging

Objective Density weighted phase-encoding has proven to be a highly efficient method for k-space sampling as it improves the localization properties and increases the signal-to-noise ratio for extended samples at the same time. But either density weighted imaging lengthens the minimum scan time or, if the Nyquist criterion is violated in parts of the sampled k-space, undersampling artefacts occur. Purpose of this work was to combine density weighted imaging and parallel imaging techniques to improve the spatial response function and consequently the signal-to-noise ratio without spoiling image quality by undersampling artefacts. Materials and Methods Images were acquired with parallel acquisition for effective density weighted imaging (PLANED imaging) and compared to results sampled with conventional Cartesian phase-encoding with the same spatial resolution and the same number of excitations. Results Both in vivo and phantom measurements recorded with the PLANED method revealed a considerable enhancement of the signal-to-noise ratio and a remarkable reduction of Gibbs artefacts compared to standard Cartesian imaging. Conclusion It has been demonstrated that PLANED improves image quality by suppressing truncation artefacts and increasing the SNR without lengthening the measurement time.     

Dynamic contrast-enhanced MR imaging of the entire breast with spectral-selective inversion fast three dimensional sequence

Dynamic contrast-enhanced images with high spatial and temporal resolutions were acquired with a fast 3D spoiled gradient echo (SPGR) sequence using spectral selective inversion recovery (IR) pulse. Five healthy volunteers and 12 patients with 14 pathologically proven breast lesions were studied. Fat suppressed volume image data covering the entire breast were obtained with a sufficient spatial resolution (0.9×1.5×3.0 mm³) and an imaging time of 57 s. By using the criteria including peripheral enhancement and presence of spiculation, sensitivity, specificity, and accuracy in detecting malignant lesions were 88.9, 80.0 and 85.%, respectively. Although the C/N and S/N ratios were approximately 30% less than those of the conventional fat suppressed 3D technique, fast 3D SPGR imaging with spectral IR method demonstrated sufficient image quality for both time intensity analysis and morphological evaluation of the breast lesions with a data acquisition time less than half of the conventional method. This technique can substantially improve spatial and temporal resolutions of dynamic MR images of the breast and will be useful in evaluating malignant and benign breast lesions.     

Identification of myocardial diffuse fibrosis by 11 heartbeat MOLLI <Emphasis Type="Italic">T</Emphasis><Subscript>1</Subscript> mapping: averaging to improve precision and correlation with collagen volume fraction

Objectives

Our objectives involved identifying whether repeated averaging in basal and mid left ventricular myocardial levels improves precision and correlation with collagen volume fraction for 11 heartbeat MOLLI T ₁ mapping versus assessment at a single ventricular level.

Materials and methods

For assessment of T ₁ mapping precision, a cohort of 15 healthy volunteers underwent two CMR scans on separate days using an 11 heartbeat MOLLI with a 5(3)3 beat scheme to measure native T ₁ and a 4(1)3(1)2 beat post-contrast scheme to measure post-contrast T ₁, allowing calculation of partition coefficient and ECV. To assess correlation of T ₁ mapping with collagen volume fraction, a separate cohort of ten aortic stenosis patients scheduled to undergo surgery underwent one CMR scan with this 11 heartbeat MOLLI scheme, followed by intraoperative tru-cut myocardial biopsy. Six models of myocardial diffuse fibrosis assessment were established with incremental inclusion of imaging by averaging of the basal and mid-myocardial left ventricular levels, and each model was assessed for precision and correlation with collagen volume fraction.

Results

A model using 11 heart beat MOLLI imaging of two basal and two mid ventricular level averaged T ₁ maps provided improved precision (Intraclass correlation 0.93 vs 0.84) and correlation with histology (R ² = 0.83 vs 0.36) for diffuse fibrosis compared to a single mid-ventricular level alone. ECV was more precise and correlated better than native T ₁ mapping.

Conclusion

T ₁ mapping sequences with repeated averaging could be considered for applications of 11 heartbeat MOLLI, especially when small changes in native T ₁/ECV might affect clinical management.

     

NMR microscopy of single neurons at 500 MHZ

Previous NMR microimaging studies at 360 MHz have demonstrated a clear differentiation between the nucleus and cytoplasm in isolated single neurons. In particular, theT ₂ of the cell nucleus is 2.5 times larger than that of the cytoplasm. In order to determine the magnitude of possibleT ₂ ^* influences on these observations, images of single cells have been obtained at 500 MHz using spin-echo and line-narrowing sequences. Comparison of the images acquired by the two sequences, and of the spin-echo images at 360 and 500 MHz, imply that anyT ₂ ^* contributions are relatively small. Consequently, the measuredT ₂ differences in spin-echo imaging represent a true difference in theT ₂ relaxation in the two cellular compartments.     

Cranial fixation plates in cerebral magnetic resonance imaging: a 3 and 7 Tesla in vivo image quality study

Objective

This study assesses and quantifies impairment of postoperative magnetic resonance imaging (MRI) at 7 Tesla (T) after implantation of titanium cranial fixation plates (CFPs) for neurosurgical bone flap fixation.

Materials and methods

The study group comprised five patients who were intra-individually examined with 3 and 7 T MRI preoperatively and postoperatively (within 72 h/3 months) after implantation of CFPs. Acquired sequences included T₁-weighted magnetization-prepared rapid-acquisition gradient-echo (MPRAGE), T₂-weighted turbo-spin-echo (TSE) imaging, and susceptibility-weighted imaging (SWI). Two experienced neurosurgeons and a neuroradiologist rated image quality and the presence of artifacts in consensus reading.

Results

Minor artifacts occurred around the CFPs in MPRAGE and T₂ TSE at both field strengths, with no significant differences between 3 and 7 T. In SWI, artifacts were accentuated in the early postoperative scans at both field strengths due to intracranial air and hemorrhagic remnants. After resorption, the brain tissue directly adjacent to skull bone could still be assessed. Image quality after 3 months was equal to the preoperative examinations at 3 and 7 T.

Conclusion

Image quality after CFP implantation was not significantly impaired in 7 T MRI, and artifacts were comparable to those in 3 T MRI.