3D Fast Imaging Research Articles

Teknik Pemeriksaan Magnetic Resonance Imaging (MRI) Brain Dengan Penambahan Sequence Axial 3D-Fiesta Pada Kasus Facial Tic

Magnetic Resonance Imaging is a medical device that combines computer technology, strong magnetic fields and radio waves to emulate representations of human body parts and produce more detailed and clear images, one of which is Facial Tic on the Brain. The MRI Brain examination aims to see the anatomy and abnormalities in the brain. This study aims to determine the MRI Brain examination procedure and the role of the Axial 3D Fiesta sequence in cases of Facial Tic. Use of the 3D Fast Imaging Employing Steady State Acquisition (FIESTA) sequence for evaluation of the head nerves. The research method used is descriptive research with a case study approach. Data collection was carried out from July 2023 to August 2023 using a GE 1.5 Tesla MRI aircraft. The subject consisted of a patient with clinical Facial Tic. Data collection was carried out through observation, interviews and documentation. The research results were obtained according to theory using sagittal T1, Coronal PD/T2, Axial PD/T2/T1/FLAIR/EPI, Axial 3D incoherent GRE T1, Axial/oblique SE MT, Axial DWI, Diffusion Tensor Imaging (DTI), Axial perfusion sequences. imaging, while in the field using localizer sequences, Axial DWI, Axial T2 Flair, Axial T2, Axial T1, Axial T2* GRE, Sagittal T1, Coronal T2, and Axial 3D Fiesta

Fast 3-D Magnetic Anomaly Forward Modeling Based on Integral Equation

Efficient and accurate 3D numerical modelling of total field magnetic anomaly is a key problem that restricts the 3D fast inversion imaging and geological interpretation of large-scale magnetic data. To address this problem, we develop a fast numerical modelling method for 3D magnetic anomaly based on integral equation. First, we derive a new analytical expression for prismatic total field magnetic anomaly, which has the advantages of compact structure and low computational cost. Then, we take advantage of the Toeplitz property of the kernel matrix when the grid is uniformly discretized in the horizontal directions to reduce the redundant computation and memory requirement without losing accuracy. In addition, the grid discretization in the vertical direction is flexible and can be finer at a shallower depth and coarser at a deeper depth, taking into account accuracy and efficiency. The 2D FFT is used to achieve fast discrete convolution of the kernel matrix and magnetic susceptibility, which greatly improves the efficiency of the discrete convolution. In the numerical examples, a cube model is designed to verify the correctness of this method. The results demonstrate that the computation time of our algorithm is reduced by 1~2 orders of magnitude, and the memory requirement is decreased by approximately 1 order of magnitude compared with the conventional fast magnetic anomaly numerical modelling method based on BTTB matrix, while achieving the same accuracy. Finally, the applicability of our algorithm is tested by calculating the terrain effect on an airborne magnetic data built in a real complex topography model.

Accelerated three-dimensional susceptibility weighted imaging of the whole spine of fetus at 3T

ObjectivesTo investigate the image quality and capability of generalized auto-calibrating partially parallel acquisition (GRAPPA) accelerated Three-dimensional (3D) susceptibility weighted imaging (SWI) of the whole spine at 3T. MethodsA total of 37 pregnant women (gestation age 22 to 39 weeks, average 29 ± 3 weeks) with suspected fetal vertebral anomalies by ultrasound (US) screening underwent 3.0T MR imaging with 3D SWI, conventional two-dimensional (2D) half-flourier acquisition single-shot turbo spin-echo (HASTE) and 3D true fast imaging with steady-state precession (True FISP). The acquisition time of each protocol was recorded. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were determined in representative interest regions of fetal thoracic vertebrae and compared among three pulse sequences. Two radiologists rated image quality independently in random order on a 5-point scale. Kappa coefficients were computed to assess inter-observer reliability. Receiver operating characteristic curves were generated, and the area under the curve (AUC) was used to compare the diagnostic performance of each protocol in vertebral deformities. ResultsThe acquisition time was 15 s for 3D-SWI and 17 s for 3D True FISP, significantly shorter than conventional HASTE (37 s; both P < 0.01).Of the three protocols, The SNR was highest on 3D True FISP, while the CNR was highest on 3D SWI. Visualization of all segments of the whole spine by 3D SWI was comparable with 3D True FISP. In contrast, 3D SWI and 3D True FISP depicted cervical and sacrococcygeal vertebrae better than HASTE. The weighted kappa statistic was 0.70–0.89 to evaluate the image quality of all segments of the whole spine, indicating good to excellent interobserver agreement. 3D SWI had the highest diagnostic performance for detecting fetal vertebral anomalies (AUC = 0.92). Conclusions3D-SWI is feasible for improved visualization of the whole fetal vertebral column and its congenital malformations with adequate image quality and high accuracy, thereby providing a supplementary method to conventional MR imaging.

A Combination of 3D TOF MRA and FIESTA Predicts Surgery-Needed Primary Trigeminal Neuralgia and Specific Offending Vessels.

To investigate the predictive accuracy of three-dimension (3D) time-of-flight (TOF) MR angiography (MRA) and 3D Fast Imaging Employing Steady-state Acquisition (FIESTA) techniques in assessing neurovascular compression (NVC) with specific vessels in patients with primary trigeminal neuralgia (TN). Patients with single-site primary TN undergoing microvascular decompression (MVD) were retrospectively recruited. All patients had available preoperative magnetic resonance imaging (MRI) scans. A quantitative NVC scoring system was applied to assess the severity of NVC on MRI. The radiological findings were correlated with the intraoperative result to determine the diagnostic accuracy of MRI techniques. Besides, the radiological indicator of MVD was determined. Seventy-three TN patients were recruited. Thirty-three patient had bilateral NVC but with unilateral neuralgia. The average NVC score of the asymptomatic side was significantly lower than that of the symptomatic side (1.6 vs. 6.7; p < 0.001). A cut-off value of NVC >4 was determined as a radiological indicator of MVD with sensitivity and specificity of 82.2% and 98.6%, respectively Area Under Curve (AUC = 0.97; p < 0.001). Approximately 90% of symptomatic patients had the distance to REZ ≤3 mm. 68.5% of patients had a single conflicting vessel, and superior cerebellar artery (SCA) was the predominate vessel (46.6%). The sensitivity and specificity of MRI to detect NVC were 95.8% and 100%, respectively. Regarding each vessel, the cohen's kappa statistic (K) was 0.632 overall. 3D TOF MRA and FIESTA show an overall good ability to predict specific offending vessels. NVC score >4 is identified to predict TN, suggestive of subsequent surgical treatment.

The preoperative evaluation value of 3D-slicer program before microsurgical vascular decompression in patients with hemifacial spasm

BackgroundTo compare the diagnostic accuracy of 3D fast imaging employing steady-state acquisition (FIESTA) combined with 3D-time-of-flight (TOF) MR angiography (MRA) sequences (FTMS) and 3D-reconstuction synthesized by 3D-slicer program in evaluation the neurovascular relationships and offending vessels preoperatively in patients with hemifacial spasm (HFS). MethodsClinical data of HFS patients who underwent microsurgical vascular decompression (MVD) were analyzed. All patients underwent MRA scans with FTMS and 3D-reconstruction before surgery. The neurovascular relationship and offending vessels were evaluated and compared with intraoperative findings. ResultsForty patients were included in this study, 18 (45%) of them were male. The mean age was 49.6 years. The Kappa identity tests identified the agreement between the FTMS and intraoperative findings in evaluating the neurovascular relationship and offending vessel was 0.263 and 0.643, respectively. The agreement between the 3D-reconstruction and intraoperative findings was 0.633 and 0.921 respectively. There was borderline significant difference between the two methods in predicting neurovascular relationship (χ2 = 9.363, P = 0.053), and there were significant differences between the two methods in predicting offending vessels (χ2 = 188.408, P < 0.001). The sensitivity and specificity of FTMS in evaluating the neurovascular relationship were 89.7% and 100%, respectively, while those with 3D-reconstruction were both 100%. Moreover, the correct 3D- reconstruction examinations in predicting vessel and nerve relationships (r = 0.634, P = 0.034) and offending vessels (r = 0.652, P = 0.028) were significantly correlated with completely symptoms remission. ConclusionsThe 3D-reconstuction synthesized by 3D-slicer program was more accurate than FTMS in preoperative evaluation of neurovascular relationship and offending vessel. The technique is expected to be helpful in preoperative evaluation. Availability of data and materialThe dataset used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Comparison of T2 Weighted, Fat-Suppressed T2 Weighted, and Three-Dimensional (3D) Fast Imaging Employing Steady-State Acquisition (FIESTA-C) Sequences in the Temporomandibular Joint (TMJ) Evaluation.

Aim Osteonecrosis can affect the mandibular condyle, and bone marrow edema may be a precursor in osteonecrosis development in temporomandibular disorder (TMD) patients. Early detection of bone marrow changes is crucial for occurring osteonecrosis. The purpose of this study was to compare the diagnostic value of fast spin-echo T2 weighted (FSE-T2W), fat-suppressed T2W (FS-T2W), and three-dimensional (3D) fast imaging employing steady-state acquisition (FIESTA-C) MR sequences for early detection of bone marrow changes as well as TMJ soft tissue alterations. Methods A total of 60 joints with TMD were included in this study using a 1.5T MR machine (Signa HDxt, GE, Milwaukee, USA) using a dual surface TMJ coil. Qualitatively, the images were interpreted by two observers for disk configuration, disk position, joint fluid, and bone marrow changes. Quantitatively, signal intensity ratios (SIR) in the TMJ condyle, retrodiscal tissue, disk, and muscle were also measured using all tested sequences. Kappa coefficients were calculated to assess both intra- and interobserver agreements for each image set. The SIR of each sequence was compared using a one-way ANOVA Bonferroni-Dunn test. Results Overall intraobserver kappa coefficients ranged between 0.35 and 0.88 for joint fluid and between 0.22 and 0.82 for bone marrow changes diagnosis, suggesting high intraobserver agreement for FS-T2W and 3D FIESTA-C sequences than FSE T2W sequence (p < 0.05). 3D FIESTA-C showed higher agreement values for disk configuration and position detection than other sequences. Conclusions 3D FIESTA-C sequences can be used and incorporated into routine MRI protocols for obtaining high-resolution TMJ MR images due to the short acquisition time and 3D nature of the sequence. Additional studies should be done for dynamic TMJ imaging with this sequence.

Vasküler loop sendromunda anterior inferior serebellar arterin çapı ve vasküler loop tipinin klinik bulgular ile ilişkisi: klinik radyoloji çalışması

Objective: Tinnitus and vertigo are common audiovestibular symptoms in the population. Many diseases can lead to the appearance of these symptoms, but the exact cause can often not be determined. It has been suggested that compression of the cranial nerves by vascular structures may be the cause of various clinical manifestations. This is known as microvascular compression syndrome. Some studies have stated that vascular compression syndromes are a serious pathology, while many studies have argued that vascular compression is only a radiological finding. We aimed to contribute to the literature on vascular compression syndrome and vascular loop types, which is still a controversial topic, and to determine the location of the diameter change in the anterior inferior cerebellar artery in the compression syndrome.&#x0D; Material and Method: Patients who underwent a Magnetic Resonance Imaging (MRI) examination of Temporal Bone due to a complaint of tinnitus or vertigo were retrospectively examined. The complaints of the patients, the diameters of the anterior inferior cerebellar artery (AICA) and the types of vascular loop were evaluated in the high resolution 3D fast imaging employing steady-state acquisition (FIESTA) sequence, according to the CHAVDA classification. The statistical relationship between the age of the patients, anterior inferior cerebellar artery diameters and vascular loop types and their clinical manifestations was investigated.&#x0D; Results: A total of 52 patients were enrolled in the study, of which 28 (53.8%) were male and 24 (46.2%) were female. The mean age of all patients was 47.58±18.734 years. The mean right AICA diameters of the patients were 1.10±0.206 mm, the mean left AICA diameter was 1.11±0.253 mm. Type 1 in 29 patients, type 2 in 12 patients, type 3 vascular loop in 4 patients were observed for the right side, while type 1 in 29 patient, type 2 in 12 patients, and type 3 in 7 patients were observed for the left side. There was no significant difference between vascular loop and tinnitus on the right and left (p=0.705; p=0.335, respectively). There was no significant difference between the right vascular loop and the left vascular loop and the vertigo (p&gt;0.999; p=0.425, respectively). There was no significant difference between the right tinnitus, left tinnitus and vertigo in terms of the diameters of the right and left AICA in the patients (p=0.782; p=0.762; p=0.408; p=0.915, respectively).&#x0D; Conclusion: Vascular compression syndromes are clinical conditions that show symptoms over cranial nerves. Although the vascular loop syndromes originating from AICA have been discussed a lot recently, it is seen that there is no definite opinion. In our study, no association of AICA diameter and vascular loop type with clinical findings was found.

NÖROTOLOJİK SEMPTOMLARI AÇIKLAMADA 7. - 8. SİNİR KOMPLEKSİ İÇİN VASKÜLER LOOP KOMPRESYONUNUN DEĞERLENDİRİLMESİ NE KADAR ETKİLİDİR ?

OBJECTIVE: The goal of this research study was to investigate of whether the radiological proof of neurovascular compression of the vestibulocochlear nerve (VCN) was pathognomonic for hearing loss and tinnitus using “3D Fast Imaging Steady-State Acquisition (FIESTA)” magnetic resonance imaging (MRI) sequence.MATERIAL AND METHODS: The research study was performed in 85 patients by evaluating 170 temporal bones, inclusive of both sides. The non-invasive assessment of the anatomical relationship between the classified vascular compression (Chavda classification) of the anterior inferior cerebellar artery (AICA) and the existence of AICA, superior cerebellar artery (SCA), vertebral artery (VA) compression or distortion of the VCN was applied by using 1.5-Tesla MRI at the internal acoustic canal (IAC).RESULTS: Of the 85 participants examined, 42.4% (n = 36) presented no vascular loop (VL). 48.2% (n = 41) of the patients produced type 1 VL, 8.2% (n = 7) type 2 VL, and 1.2% (n = 1) type 3 VL accordingly to the Chavda classification. In addition, compressions of redundant VA and SCA were also observed in 7.1% (n = 6) and 3.5% (n = 3) of the patients respectively. Also, IAC distortion was found in 32% (n = 16) patients with tinnitus. The presence of vascular loops also showed a high incidence in patients with normal hearing (51.8%) and without tinnitus (62.9%), respectively. No statistically relevant variations were found between the existence and nonexistence of the VL of AICA forms, VA or SCA, and IAC distortion for the neurotological symptoms of patients (p &amp;gt; 0.05).CONCLUSIONS: Neurovascular touch is not an uncommon finding. It doesn’t appear to be related to tinnitus. However, the use of 3D-FIESTA MRI well defines the relationship between VCN and adjacent vascular variations and especially AICA variations and contributes to case selection for microvascular operations.

Compressed-sensing accelerated magnetic resonance imaging of inner ear.

ObjectiveTo compare conventional method and compressed‐sensing (CS) accelerated 3D balanced fast field echo imaging (bFFE) of inner ear.MethodsTwenty patients with suspected inner ear disease underwent CS accelerated 3D‐bFFE (CS‐bFFE) and conventional 3D‐bFFE (Con‐bFFE) by a 3T MRI. The overall image quality, motion artifacts, and image quality of specific structures of inner ear were assessed on ordinal scales by three radiologists who were blinded to the scan protocols. Kendall W test was used to evaluate interobserver agreement and Wilcoxon test was performed to compare the image quality and motion artifacts between CS‐bFFE and Con‐bFFE.ResultsThe acquisition duration of CS‐bFFE (1 min 53 s) was 49% faster than Con‐bFFE. Three radiologists had good inter‐observer agreement of image quality (Kendall W value of 0.829 for CS‐bFFE and 0.815 for Con‐bFFE) and motion artifacts evaluation (Kendall W value of 0861 for CS‐bFFE and 0.707 for Con‐bFFE). The better overall image quality of CS‐bFFE was assessed (4.93 ± 0.23 for CS‐bFFE, 4.53 ± 0.70 for Con‐bFFE, Z = −2.254, p = 0.024). The image quality score of facial and cochlear nerve gained higher in CS‐bFFE (4.93 ± 0.23 for CS‐bFFE, 4.58 ± 0.64 for Con‐bFFE, Z = −2.094, p = 0.036). No significant difference of motion artifacts (p = 0.050) between CS‐bFFE and Con‐bFFE.ConclusionsThe CS‐bFFE improves image quality and reduces acquisition time significantly, and it is a feasible MRI protocol for inner ear imaging.

Usefulness of three-dimensional fast imaging employing steady-state acquisition MRI of large vessel occlusion for detecting occluded middle cerebral artery and internal carotid artery before acute mechanical thrombectomy.

Objective Acute mechanical thrombectomy (AMT) in patients with acute ischemic stroke from large vessel occlusion (LVO) is performed without directly identifying the occluded vessels. In this study, we evaluated whether 1.5 T magnetic resonance imaging (MRI) with 3D-fast imaging employing steady-state acquisition (FIESTA) could visualize the occluded intracranial middle cerebral artery (MCA) and internal carotid artery (ICA) before AMT.Methods This retrospective study included 21 consecutive patients who underwent time-of-flight magnetic resonance angiography (TOF MRA) and 3D-FIESTA MRI immediately before AMT. The patients also underwent TOF MRA after AMT and achieved TICI 2b or 3 by AMT at our hospital between February 2018 and April 2019. When LVO in the anterior circulation was detected by TOF MRA, 3D-FIESTA MRI was additionally performed. Then, the occluded intracranial MCA and ICA, including their branches, were constructed on the workstation with volume rendering. The obtained images were fused with the TOF MRA images to create combined 3D images.Results The length and top-to-bottom distance of the affected M1 segment (calculated by the ipsilateral-to-contralateral ratio) were 1.29 and 1.17, respectively, on 3D-FIESTA MRI before AMT and 1.34 and 1.24, respectively, on TOF MRA after AMT. We assessed the number of M2 segments branching from the affected M1/M2 junction and visualized the affected anterior temporal artery. The 3D-FIESTA MRI before AMT and TOF MRA after AMT were consistent in all patients, except for two who moved vigorously during imaging.Conclusions Images acquired by 1.5T 3D-FIESTA MRI can visualize to predict the existing path of the occluded MCA and ICA before AMT in patients with LVO of the anterior circulation.

3D MRI of the Knee.

Three-dimensional (3D) magnetic resonance imaging (MRI) of the knee is widely used in musculoskeletal (MSK) imaging. Currently, 3D sequences are most commonly used for morphological imaging. Isotropic 3D MRI provides higher out-of-plane resolution than standard two-dimensional (2D) MRI, leading to reduced partial volume averaging artifacts and allowing for multiplanar reconstructions in any plane with any thickness from a single high-resolution isotropic acquisition. Specifically, isotropic 3D fast spin-echo imaging, with options for tissue weighting similar to those used in multiplanar 2D FSE imaging, is of particular interest to MSK radiologists. New applications for 3D spatially encoded sequences are also increasingly available for clinical use. These applications offer advantages over standard 2D techniques for metal artifact reduction, quantitative cartilage imaging, nerve imaging, and bone shape analysis. Emerging fast imaging techniques can be used to overcome the long acquisition times that have limited the adoption of 3D imaging in clinical protocols.

Effects of B0 eddy currents on imaging isocenter shifts in 0.35‐T MRI‐guided radiotherapy (MR‐IGRT) system

PurposeThe purpose of this study was to measure gantry angle‐related eddy currents in a 0.35‐T MRI‐Linac and determine if B0 (zeroth order) eddy currents are the primary cause of gantry angle‐dependent imaging isocenter shifts vs other potential causes like B0 inhomogeneities and gradient (first order) eddy currents. For conventional Cartesian acquisitions, B0 eddy currents can cause imaging isocenter shifts along both phase encode and readout directions. Gradient eddy currents can cause spatial distortion along both the phase encode and readout directions. Center frequency offsets can cause imaging isocenter shifts along the readout direction that vary with readout gradient polarity.MethodsMRI‐related eddy currents and imaging isocenter shifts were measured on a 0.35‐T MRI‐Linac at gantry angles from 0° to 330° in increments of 30°. All measurements were made after gradient shimming and center frequency tuning at each planned gantry angle. Eddy current and field homogeneity measurements were conducted using a 24‐cm diameter spherical phantom. Gradient and B0 eddy currents were calculated from the free induction decays (FIDs) resulting from selective excitation of slices located ±5 cm from isocenter. B0 eddy currents were also calculated from FIDs acquired with nonselective excitation and compared with B0 eddy current values derived using selective excitation. B0 inhomogeneities and center frequency offsets were measured by acquiring FIDs with nonselective excitation. Imaging isocenter shifts were measured using a 33x33x10.5 cm3 uniformity linearity (grid) phantom and a 3D true fast imaging with steady‐state precession (TrueFISP) sequence used in MRI‐guided radiation therapy. Eddy currents were compared to vendor specifications and correlated with the imaging isocenter shifts. Measurements were conducted before and after the MRI‐Linac’s waveguide was replaced with an updated design to reduce eddy currents.ResultsB0 eddy currents were highly correlated (r = 0.986, P &lt;&lt; 0.001) for measurements made with vs without selective excitation. Transverse (X and Y) axis B0 eddy currents before and after the waveguide upgrade were out of specification (specification: ≤0.1 μT m/mT for delays &lt; 10 ms) for most of the measured gantry angles. Gradient eddy currents before and after the upgrade were within specifications for the measured gantry angles (≤0.1% for delays &lt; 10 ms). B0 eddy currents and imaging isocenter shifts were highly correlated (r = 0.965, P &lt;&lt; 0.001). After the Linac waveguide upgrade, root mean square (RMS) peak B0 and gradient eddy currents dropped 45% and 11%, respectively, for delays &lt;10 ms, while imaging isocenter shifts dropped 53%. Isocenter shifts were observed in both phase encode and readout directions. Center frequency offsets were &lt;26 Hz while B0 inhomogeneities were &lt;33 Hz full width at half maximum (FWHM).ConclusionsImaging isocenter shifts measured in a 0.35‐T MRI‐Linac were highly correlated with B0 eddy currents. The eddy currents and imaging isocenter shifts decreased after the MRI‐Linac’s waveguide was replaced.

3D magnetic resonance fingerprinting with quadratic RF phase.

To implement 3D magnetic resonance fingerprinting (MRF) with quadratic RF phase (qRF-MRF) for simultaneous quantification of T1 , T2 , ΔB0 , and . 3D MRF data with effective undersampling factor of 3 in the slice direction were acquired with quadratic RF phase patterns for T1 , T2 , and sensitivity. Quadratic RF phase encodes the off-resonance by modulating the on-resonance frequency linearly in time. Transition to 3D brings practical limitations for reconstruction and dictionary matching because of increased data and dictionary sizes. Randomized singular value decomposition (rSVD)-based compression in time and reduction in dictionary size with a quadratic interpolation method are combined to be able to process prohibitively large data sets in feasible reconstruction and matching times. Accuracy of 3D qRF-MRF maps in various resolutions and orientations are compared to 3D fast imaging with steady-state precession (FISP) for T1 and T2 contrast and to 2D qRF-MRF for contrast and ΔB0 . The precision of 3D qRF-MRF was 1.5-2 times higher than routine clinical scans. 3D qRF-MRF ΔB0 maps were further processed to highlight the susceptibility contrast. Natively co-registered 3D whole brain T1 , T2 , , ΔB0 , and QSM maps can be acquired in as short as 5 min with 3D qRF-MRF.

SPARC: Simultaneous Assessment of Gastric Emptying and Motility with Contrast Enhanced Magnetic Resonance Imaging in Humans

PurposeMagnetic resonance imaging (MRI) of the gastrointestinal (GI) tract is an emerging technique for non‐invasive assessment of gastric emptying and motility in animals and humans. However, addition of MRI contrast agents to the test meal is often required to produce high luminal contrast to facilitate image analysis. Here, we reported a recipe of a test meal that is all natural (e.g. gadolinium‐free) and safe for humans. The ingredients of the test meal all contain relatively high concentration of manganese, which allow the lumen of the GI tract to be visible inside MRI. To capture gastric emptying and motility simultaneously, we have developed a dynamic 3D imaging protocol with high spatial and temporal resolution and an image segmentation and analysis algorithm.MethodSix healthy volunteers (3 woman; age 24–31) participated in this study. All subjects were asked to fast for 12 hours. Subjects were scanned using a 3T Siemens Prisma MRI scanner using an 18‐channel body coil and a 32‐channel spine coil. Prior to meal consumption, pre‐prandial gastric volume was quantified using a 3D true fast imaging (TRUFI) with steady‐state free precession sequence under free breathing. Then the subjects were instructed to ingest 350 ml of a semi‐solid test meal (263kcal) that contains blended natural foods (i.e. pineapple, banana, blueberry, firm tofu) with a relatively high concentration of manganese. Post‐meal MRI scans were performed using a 3D Spoiled Gradient Echo Variant (VIBE) sequence under gentle breaths over a 90‐minute time course. Post‐prandial gastric volumes, as well as antral contraction frequency and amplitude of the peristaltic wave, were quantified from the dynamic 3D MRI images using a custom‐built image processing pipeline.ResultsPre‐prandial gastric volume was measured prior to test meal consumption (30.98±12.29 mL). After the subjects consumed the test meal, the presence of manganese in the meal enhanced the contrast of the gastric lumen (Fig. 1). The imaging protocol collected fast real‐time MRI scans of the stomach processing and emptying of a meal and the algorithms quantified gastric motility and emptying rate. The stomach volume decreased at a rate of 1.58±0.50 mL/min, mainly attributed to volume decrease in the fundus and the corpus (1.31±0.53 mL/min) than in the antrum (0.28±0.15 mL/min). The frequency of gastric contractions was 2.79±0.17 cycles/min, which was in line with the frequency of gastric slow wave in humans. The displacement of the luminal wall (i.e. contraction amplitude) was greater at the antrum (7.42±1.39 mm) than at the fundus and the corpus (4.52±0.25 mm), as illustrated in Fig. 2.ConclusionHere, we developed a contrast‐enhanced gastric MRI protocol to non‐invasively monitor gastric emptying and motility in humans. Such experimental protocol was further empowered by advanced image analysis to enable comprehensive assessment of gastric functions and physiology. In summary, the proposed method may become a reliable standard to guide diagnosis and treatment of gastric disorders in humans.Support or Funding InformationNIH SPARC OT2OD023847Example gastric MRI images of the stomach distended with the test meal. The contrast of the gastric lumen was significantly enhanced due to the presence of manganese in the meal.Figure 1Mapping amplitude of gastric contractions on the luminal wall. The displacement of the luminal wall was greatest at the antrum, followed by the corpus, and smallest at the fundus.Figure 2

Facial nerve atrophy in patients with amyotrophic lateral sclerosis: Evaluation with fast imaging employing steady‐state acquisition (FIESTA)

In amyotrophic lateral sclerosis (ALS), motor neurons in the brainstem markedly deplete, whereas sensory neurons are less severely affected. To determine whether facial nerve (FN) measurement on 3D fast imaging employing steady-state acquisition (FIESTA) is useful for ALS diagnosis. Retrospective. Fifteen ALS patients and 16 controls. 3T FIESTA MR. The cross-sectional area of the FN and cochlear nerve (CN) were measured, and the FN/CN ratio (FCR) was assessed. For qualitative assessment, the FN cross-sectional area was compared with that of the CN and the following scores were assigned: score 1 (large), the FN is larger than the CN; score 2 (almost equal), the size difference between the FN and CN is within 10%; score 3 (small), the FN is smaller than the CN (10-50%); score 4 (significantly small), size of the FN is less than half the size of the CN. The differences in FCR between the ALS patients and the controls were tested using the Wilcoxon Mann-Whitney U-test. For the qualitative and quantitative assessments, we performed a receiver operating characteristic analysis for the diagnosis of ALS with an abnormal finding as score 3 or 4. The mean FCR was significantly smaller for ALS patients (0.71 ± 0.17) than for controls (0.95 ± 0.08) (P < 0.001) and the area under the curve was 0.93. When an FN score was 3 or 4, indicative of FN atrophy, the sensitivity and specificity values of FIESTA for discriminating ALS patients from controls were 93.3% (14/15) and 90.0% (18/20), respectively. The FN atrophy revealed on FIESTA, which may reflect lower motor neuron impairment in ALS, allowed us to distinguish ALS patients from controls with a high degree of accuracy. 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:757-766.

Accuracy of computed tomography: magnetic resonance imaging image fusion using a phantom for skull base surgery.

The aim of this study is to assess the positional accuracy of image fusions of the skull base region using different magnetic resonance imaging (MRI) and computed tomography (CT) image pairs. An image set of 3D fast imaging employing steady-state acquisition-C (FIESTA-C) was used as the base image set. Image fusions were performed using an image set with different fields of view (FOVs): one with different matrix size, one with a different sequence of 3D spoiled gradient recalled acquisition, and one with different modality (CT), using a phantom including multi columnar objects. Position of columns at the center, and 4 and 8 cm from the center were measured. The displacements between the base image set and fused image set were measured. For slices with different z-positions, the displacement of the 8-cm column was assessed. For 20 clinical MRI cases, the distance between the dorsum sellae and the cranial nerves was measured. No significant differences were found between the different FOVs or image sequences. However, with the different matrix sizes and modalities, significant displacements were observed, although they were all within 0.5 mm. Similar displacements were observed in the slices at different z-positions. All cranial nerves were located within 40 mm of the dorsum sellae. The displacements following image fusion were within approximately 0.5 mm, even at 8 cm from the center. This suggests that the region where the cranial nerves are located, within 40 mm of the dorsum sellae, had no risk of positional error following image fusion.

Pincer‐type MRI morphology seen in over a third of asymptomatic healthy volunteers without femoroacetabular impingement

In daily routine, pincer femoroacetabular impingement (FAI) findings are often seen without a clinical diagnosis of pincer FAI. To assess the presence of pincer FAI MRI findings in asymptomatic volunteers with negative impingement test versus patients with clinically confirmed FAI. Case-control study. Sixty-three asymptomatic volunteers and 63 matched patients with FAI were included. A coronal T1 -weighted turbo spin-echo sequence as well as a 3D oblique transverse water-excitation true fast imaging sequence at 1.5T. The volunteers underwent standard MRI of the hip, and patients underwent MR arthrography of the symptomatic hip using the same MR sequences. Measurements of cranial acetabular version, acetabular depth, and lateral center-edge angle were performed independently by three fellowship-trained musculoskeletal radiologists. Descriptive statistics, Mann-Whitney U-test, Unpaired t-test, receiver operating characteristics (ROC), Intraclass correlation coefficient (ICC). Forty-one percent (26/63, reader 1), 32% and 37% (20 and 23/63, reader 2/3) of asymptomatic volunteers had at least one positive MR finding for pincer-FAI. Patients with pincer or mixed-type FAI had cranial retroversion of the acetabulum of -0.2° ± 7.1 (mean ± standard deviation) for reader 1 and -0.3° ± 5.5/-0.2° ± 4.8 for reader 2 / reader 3, while asymptomatic volunteers had an anteversion of 6.2° ± 6.4 (reader 1) and 3.2° ± 4.9/3.1° ± 6.5 (readers 2/3): This difference was statistically significant (P ≤ 0.002), but there was a large overlap between the groups. Acetabular depth measurements were very similar for patients with either pincer or mixed-type FAI (5.1-5.3 mm ± 3.1) and volunteers (5.2-6.1 mm ± 2.6), without a statistically significant difference (P ≤ 0.50). Lateral center-edge angle was also similar in patients with either pincer or mixed-type FAI (32.1-35.1° ± 9.1) and volunteers (30.7-33.2° ± 6.5), without a statistically significant difference (P ≤ 0.28). There is a large overlap in pincer-type MRI findings between patients with symptomatic FAI and asymptomatic volunteers. More than a third of volunteers exhibited at least one positive pincer-type MRI finding. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1296-1303.

Potential Clinical Benefits and Limitation of Foetal Virtuopsy Using a High-Field MRI of 7 Tesla to Assess First Trimester Foetuses Versus Stereomicroscopic Autopsy

Background: Performing accurate autopsies on small foetuses is a difficult process to achieve, especially when a certain degree of autolysis is involved. High-field MRI of 7 T has proven to be a useful tool to describe small foetuses anatomy, therefore the purpose of our study was to establish its diagnostic usefulness assessing first trimester foetuses compared to stereomicroscopic autopsy or microscopic evaluation. Methods Nine consecutive cases of first trimester foetuses were divided in two groups according to gestational age and crown-rump length (Embryo Group cases of 9-10 gestational weeks and Foetal Group cases of 13 gestational weeks) and scanned using a 3D Fast Imaging with Steady Procession 3D (FISP 3D) respectively 2D Turbo High Resolution T2 WI protocol. Images were interpreted by a radiologist, and two embryologists. All cases were submitted to invasive autopsy, blinded to the imagistic results. Findings Virtuopsy brought important additional information in all cases from the Embryo Group and had similar diagnostic capacity as the conventional method in evaluating the cases from the Foetal Group. The Cohen's kappa coefficient of agreement was k=0.92 (95% CI 82-97), highlighting a very good concordance between foetal virtuopsy and stereomicroscopic autopsy, also supported by the McNemar test p =1.00. The imagistic method presented a better capacity in visualising embryonic structure especially embryonic brain with lesser method disadvantages (p=0,005.) and similar capacity for visualising foetal structures in the second group. Interpretation Virtual autopsy using high field MRI at 7T is emerging as a promising alternative approach to stereomicroscopic autopsy in the assessment of malformed first trimester human foetuses. Funding: Not applicable. Declaration of Interest: The authors report no declarations of interest. Ethical Approval: The study protocol was approved by the “Iuliu Hatieganu” University of Medicine and Pharmacy Ethics Committee and written informed parental consent was obtained before the imagistic and conventional autopsy procedures.

Evaluation of Peritumoral Brain Parenchyma Using Contrast-Enhanced 3D Fast Imaging Employing Steady-State Acquisition at 3T for Differentiating Metastatic Brain Tumors and Glioblastomas

Metastatic brain tumors and glioblastomas are the 2 of the most common brain neoplasms in adults. However, distinguishing solitary metastatic brain tumors from glioblastomas on conventional magnetic resonance imaging remains particularly challenging. Thus, we aimed to retrospectively assess the role of contrast-enhanced fast imaging employing steady-state acquisition (CE-FIESTA) imaging in distinguishing between metastatic brain tumors and glioblastomas. Forty-three patients with metastatic brain tumors and 14 patients with glioblastomas underwent conventional magnetic resonance imaging and CE-FIESTA before surgery. First, 1 neuroradiologist and 1 neurosurgeon classified the CE-FIESTA findings for the peritumoral brain parenchyma by consensus. Next, the 2 neuroradiologists performed an observer performance study comparing tumor shape classification (smooth or irregular margins), a classic imaging finding, with the CE-FIESTA classification of the peritumoral brain parenchyma. The CE-FIESTA findings for the peritumoral brain parenchyma were classified as follows: type A, no hyperintense rim; type B, partial hyperintense rim; and type C, extended hyperintense rim. With regard to the diagnosis of metastatic brain tumors, the observer performance study demonstrated that the mean sensitivity, specificity, and accuracy of an extended hyperintense rim classification (type C) on CE-FIESTA images were 95.3%, 85.7%, and 93.0%, respectively. The accuracy of the CE-FIESTA classification was significantly higher than that of the tumor shape classification. CE-FIESTA images may provide useful information for distinguishing metastatic brain tumors from glioblastomas, especially when focusing on differences in the peritumoral brain parenchyma.

Application of 3D Fast Spin-Echo T1 Black-Blood Imaging in the Diagnosis and Prognostic Prediction of Patients with Leptomeningeal Carcinomatosis

Contrast-enhanced 3D fast spin-echo T1 black-blood imaging selectively suppresses the signal of blood flow and could provide a higher contrast-to-noise ratio compared with contrast-enhanced 3D ultrafast gradient recalled echo (contrast-enhanced gradient recalled echo) and 2D spin-echo T1WI (contrast-enhanced spin-echo). The purpose of our study was to evaluate whether black-blood imaging can improve the diagnostic accuracy for leptomeningeal carcinomatosis compared with contrast-enhanced gradient recalled-echo and contrast-enhanced spin-echo and, furthermore, to determine whether the grade of leptomeningeal carcinomatosis evaluated on black-blood imaging is a significant predictor of progression-free survival. Leptomeningeal carcinomatosis (n = 78) and healthy (n = 31) groups were enrolled. Contrast-enhanced gradient recalled-echo, contrast-enhanced spin-echo, and black-blood imaging were separately reviewed, and a diagnostic rating (positive, indeterminate, or negative) and grading of leptomeningeal carcinomatosis were assigned. The diagnostic accuracies of the 3 imaging sequences were compared in terms of leptomeningeal carcinomatosis detection. The Kaplan-Meier and the Cox proportional hazards model analyses were performed to determine the relationship between the leptomeningeal carcinomatosis grade evaluated on black-blood imaging and progression-free survival. Black-blood imaging showed a significantly higher sensitivity (97.43%) than contrast-enhanced gradient recalled-echo (64.1%) and contrast-enhanced spin-echo (66.67%) (P < .05). In terms of specificities, we did not find any significant differences among contrast-enhanced gradient recalled-echo (90.32%), contrast-enhanced spin-echo (90.32%), and black-blood imaging (96.77%) (P > .05). A Cox proportional hazards model identified the time to metastasis, Karnofsky Performance Scale status, and a combination of the leptomeningeal carcinomatosis grade with a linear pattern as independent predictors of progression-free survival (P < .05). Black-blood imaging can improve the diagnostic accuracy and predict progression-free survival in patients with leptomeningeal carcinomatosis.