As fast as an X-ray: real-time magnetic resonance imaging for diagnosis of idiopathic scoliosis in children and adolescents.

BACKGROUND: Idiopathic scoliosis is common in adolescence. Due to the rapid growth of the spine, it must be monitored closely with radiographs to ensure timely intervention when therapy is needed. As these radiographs continue into young adulthood, patients are repeatedly exposed to ionizing radiation. OBJECTIVE: This study aimed to investigate whether real-time magnetic resonance imaging (MRI) is equivalent to conventional radiography in juvenile idiopathic scoliosis for determining curvature, rotation and the Risser stage. Additionally, the time requirement should be quantified. MATERIALS AND METHODS: Children with idiopathic scoliosis who had postero-anterior whole-spine radiography for clinical indications were included in this prospective study. A real-time spine MRI was performed at 3 tesla in the supine position, capturing images in both the coronal and sagittal planes. The scoliosis was assessed using Cobb angle, rotation was evaluated based on Nash and Moe criteria, and the Risser stage was determined for each modality. The correlations between modalities and a correction factor for the Cobb angle between the standing and supine position were calculated. RESULTS: A total of 33 children (aged 5-17 years), who met the inclusion criteria, were recruited. The Cobb angle (R2 = 0.972; P < 0.01) was positively correlated with a correction factor of 1.07 between modalities. Additionally, the degree of rotation (R2 = 0.92; P < 0.01) and the Risser stage (R2 = 0.93; P < 0.01) demonstrated a strong correlation. CONCLUSION: Real-time MRI is equivalent to conventional radiography in determining baseline parameters. Furthermore, it is radiation-free and less time-consuming.

Increased Musculoskeletal Deformities And Decreased Lung Volume In Patients After Ea/Tef Repair - A Real-Time Mri Study.

OBJECTIVE: This study aims to assess morphological and functional postoperative changes after open or minimally invasive (MIS) repair of esophageal atresia (EA) compared to healthy controls by thoracic real-time MRI. SUMMARY BACKGROUND DATA: Musculoskeletal deformities and pulmonary morbidity are common in children after EA repair. The real-time MRI is a novel technique that provides ultrafast, high-quality images during spontaneous breathing, without sedation even in young children. METHODS: Children aged 3-18 years were prospectively examined with a 3 Tesla MRI. Musculoskeletal deformities, static thoracic cross-sectional areas (CSA) at three different levels and lung volumes, as well as dynamic right-to-left ratio of CSA of hemithoraces and lung volumes during forced breathing were evaluated. RESULTS: 72 children (42 open, 8 MIS, 22 controls) were recruited. In the EA group, rib fusions and adhesions (78%, P<0.01) and scoliosis (15%, P=0.32) were found after thoracotomy, but not after MIS. Mean right-to-left ratio of CSA and lung volumes were lower after EA repair compared to controls (P <0.05), indicating impaired thoracic and lung development. The number of thoracotomies was a significant risk factor for smaller thoracic volumes (P<0.05). CONCLUSIONS: For the first time, morphological changes and thoracic motility after EA repair were visualized by dynamic real-time MRI. Children after EA repair show decreased right-sided thoracic and lung development compared to controls. Open repair leads to significantly more musculoskeletal deformities. This study emphasizes that musculoskeletal morbidity following a thoracotomy in infancy is high.

CSF and venous blood flow from childhood to adulthood studied by real-time phase-contrast MRI.

PURPOSE: In vivo measurements of CSF and venous flow using real-time phase-contrast (RT-PC) MRI facilitate new insights into the dynamics and physiology of both fluid systems. In clinical practice, however, use of RT-PC MRI is still limited. Because many forms of hydrocephalus manifest in infancy and childhood, it is a prerequisite to investigate normal flow parameters during this period to assess pathologies of CSF circulation. This study aims to establish reference values of CSF and venous flow in healthy subjects using RT-PC MRI and to determine their age dependency. METHODS: RT-PC MRI was performed in 44 healthy volunteers (20 females, age 5-40 years). CSF flow was quantified at the aqueduct (Aqd), cervical (C3) and lumbar (L3) spinal levels. Venous flow measurements comprised epidural veins, internal jugular veins and inferior vena cava. Parameters analyzed were peak velocity, net flow, pulsatility, and area of region of interest (ROI). STATISTICAL TESTS: linear regression, student's t-test and analysis of variance (ANOVA). RESULTS: In adults volunteers, no significant changes in flow parameters were observed. In contrast, pediatric subjects exhibited a significant age-dependent decrease of CSF net flow and pulsatility in Aqd, C3 and L3. Several venous flow parameters decreased significantly over age at C3 and changed more variably at L3. CONCLUSION: Flow parameters varies depending on anatomical location and age. We established changes of brain and spinal fluid dynamics over an age range from 5-40 years. The application of RT-PC MRI in clinical care may improve our understanding of CSF flow pathology in individual patients.

Dynamic assessment of scapholunate ligament status by real-time magnetic resonance imaging: an exploratory clinical study.

OBJECTIVE: Clinical-standard MRI is the imaging modality of choice for the wrist, yet limited to static evaluation, thereby potentially missing dynamic instability patterns. We aimed to investigate the clinical benefit of (dynamic) real-time MRI, complemented by automatic analysis, in patients with complete or partial scapholunate ligament (SLL) tears. MATERIAL AND METHODS: Both wrists of ten patients with unilateral SLL tears (six partial, four complete tears) as diagnosed by clinical-standard MRI were imaged during continuous active radioulnar motion using a 1.5-T MRI scanner in combination with a custom-made motion device. Following automatic segmentation of the wrist, the scapholunate and lunotriquetral joint widths were analyzed across the entire range of motion (ROM). Mixed-effects model analysis of variance (ANOVA) followed by Tukey's posthoc test and two-way ANOVA were used for statistical analysis. RESULTS: With the increasing extent of SLL tear, the scapholunate joint widths in injured wrists were significantly larger over the entire ROM compared to those of the contralateral healthy wrists (p<0.001). Differences between partial and complete tears were most pronounced at 5°-15° ulnar abduction (p<0.001). Motion patterns and trajectories were altered. Complete SLL deficiency resulted in complex alterations of the lunotriquetral joint widths. CONCLUSION: Real-time MRI may improve the functional diagnosis of SLL insufficiency and aid therapeutic decision-making by revealing dynamic forms of dissociative instability within the proximal carpus. Static MRI best differentiates SLL-injured wrists at 5°-15° of ulnar abduction.

Whole-body magnetic resonance imaging in two minutes: cross-sectional real-time coverage of multiple volumes.

This work describes a novel technique for rapid and motion-robust whole-body magnetic resonance imaging (MRI). The method employs highly undersampled radial fast low angle shot (FLASH) sequences to cover large volumes by cross-sectional real-time MRI with automatic slice advancement after each frame. The slice shift typically amounts to a fraction of the slice thickness (e.g., 10% to 50%) in order to generate a successive series of partially overlapping sections. Joint reconstructions of these serial images and their respective coil sensitivity maps rely on nonlinear inversion (NLINV) with regularization to the image and sensitivity maps of a preceding frame. The procedure exploits the spatial similarity of neighboring sections. Whole-body scanning is accomplished by measuring multiple volumes at predefined locations, i.e., at fixed table positions, in combination with intermediate automatic movements of the patient table. Individual volumes may take advantage of different field-of-views, image orientations, spatial and temporal resolutions as well as contrasts. Preliminary proof-of-principle applications to healthy subjects at 3 T without cardiac gating and during free breathing yield high-quality anatomic images with acquisition times of less than 100 ms. Spin-density and T1 contrasts are obtained by spoiled FLASH sequences, while T2-type (i.e., T2/T1) contrast results from refocused FLASH sequences that generate a steady state free precession (SSFP) free induction decay (FID) signal. Total measuring times excluding vendor-controlled adjustment procedures are less than two minutes for a 100 cm scan that, for example, covers the body from head to thigh by three optimized volumes and more than 1,300 images. In conclusion, after demonstrating technical feasibility the proposed method awaits clinical trials.

Visualization of deglutition and gastroesophageal reflux using real-time MRI: a standardized approach to image acquisition and assessment.

This study aims to develop a standardized algorithm for gastroesophageal image acquisition and diagnostic assessment using real-time MRI. Patients with GERD symptoms undergoing real-time MRI of the esophagus and esophagogastric junction between 2015 and 2018 were included. A 10 ml bolus of pineapple juice served as an oral contrast agent. Patients performed Valsalva maneuver to provoke reflux and hiatal hernia. Systematic MRI assessment included visual presence of achalasia, fundoplication failure in patients with previous surgical fundoplication, gastroesophageal reflux, and hiatal hernia. A total of 184 patients (n = 92 female [50%], mean age 52.7 ± 15.8 years) completed MRI studies without adverse events at a mean examination time of 15 min. Gastroesophageal reflux was evident in n = 117 (63.6%), hiatal hernia in n = 95 (52.5%), and achalasia in 4 patients (2.2%). Hiatal hernia was observed more frequently in patients with reflux at rest (n = 67 vs. n = 6, p < 0.01) and during Valsalva maneuver (n = 87 vs. n = 8, p < 0.01). Real-time MRI visualized a morphologic correlate for recurring GERD symptoms in 20/22 patients (90%) after fundoplication procedure. In a large-scale single-center cohort of patients with GERD symptoms undergoing real-time MRI, visual correlates for clinical symptoms were evident in most cases. The proposed assessment algorithm could aid in wider-spread utilization of real-time MRI and provides a comprehensive approach to this novel imaging modality.

First experience with real-time magnetic resonance imaging-based investigation of respiratory influence on cardiac function in pediatric congenital heart disease patients with chronic right ventricular volume overload.

BACKGROUND: Congenital heart disease (CHD) is often associated with chronic right ventricular (RV) volume overload. Real-time magnetic resonance imaging (MRI) enables the analysis of cardiac function during free breathing. OBJECTIVE: To evaluate the influence of respiration in pediatric patients with CHD and chronic RV volume overload. METHODS AND MATERIALS: RV volume overload patients (n=6) and controls (n=6) were recruited for cardiac real-time MRI at 1.5 tesla during free breathing. Breathing curves from regions of interest reflecting the position of the diaphragm served for binning images in four different tidal volume classes, each in inspiration and expiration. Tidal volumes were estimated from these curves by data previously obtained by magnetic resonance-compatible spirometry. Ventricular volumes indexed to body surface area and Frank-Starling relationships referenced to the typical tidal volume indexed to body height (TTVi) were compared. RESULTS: Indexed RV end-diastolic volume (RV-EDVi) and indexed RV stroke volume (RV-SVi) increased during inspiration (RV-EDVi/TTVi: RV load: + 16 ± 4%; controls: + 22 ± 13%; RV-SVi/TTVi: RV load: + 21 ± 6%; controls: + 35 ± 17%; non-significant for comparison). The increase in RV ejection fraction during inspiration was significantly lower in RV load patients (RV load: + 1.1 ± 2.2%; controls: + 6.1 ± 1.5%; P=0.01). The Frank-Starling relationship of the RV provided a significantly reduced slope estimate in RV load patients (inspiration: RV load: 0.75 ± 0.11; controls: 0.92 ± 0.02; P=0.02). CONCLUSION: In pediatric patients with CHD and chronic RV volume overload, cardiac real-time MRI during free breathing in combination with respiratory-based binning indicates an impaired Frank-Starling relationship of the RV.

Turbulence in surgical suction heads as detected by MRI.

BACKGROUND: Blood loss is common during surgical procedures, especially in open cardiac surgery. Allogenic blood transfusion is associated with increased morbidity and mortality. Blood conservation programs in cardiac surgery recommend re-transfusion of shed blood directly or after processing, as this decreases transfusion rates of allogenic blood. But aspiration of blood from the wound area is often associated with increased hemolysis, due to flow induced forces, mainly through development of turbulence. METHODS: We evaluated magnetic resonance imaging (MRI) as a qualitative tool for detection of turbulence. MRI is sensitive to flow; this study uses velocity-compensated T1-weighted 3D MRI for turbulence detection in four geometrically different cardiotomy suction heads under comparable flow conditions (0-1250 mL/min). RESULTS: Our standard control suction head Model A showed pronounced signs of turbulence at all flow rates measured, while turbulence was only detectable in our modified Models 1-3 at higher flow rates (Models 1 and 3) or not at all (Model 2). CONCLUSIONS: The comparison of flow performance of surgical suction heads with different geometries via acceleration-sensitized 3D MRI revealed significant differences in turbulence development between our standard control Model A and the modified alternatives (Models 1-3). As flow conditions during measurement have been comparable, the specific geometry of the respective suction heads must have been the main factor responsible. The underlying mechanisms and causative factors can only be speculated about, but as other investigations have shown, hemolytic activity is positively associated with degree of turbulence. The turbulence data measured in this study correlate with data from other investigations about hemolysis induced by surgical suction heads. The experimental MRI technique used showed added value for further elucidating the underlying physical phenomena causing blood damage due to non-physiological flow.

Real-time MRI: a new tool of radiologic imaging in small children.

Real-time MRI (rt-MRI) in children is a new imaging technique that combines the advantages of US - at frame rates of up to 50 images per second - with the quality and features of MRI. Although still subject of research, it has become a standard tool in the diagnostic portfolio of two pediatric radiology departments in Germany. Based on ultrashort acquisition times, any detrimental effects of macroscopic movements of the child and the physiological movements of the organs are negligible. Especially in pediatric brain imaging, rt-MRI has already proven its value. With suitable indications, rt-MRI can reduce anesthesia and sedation examinations in children below 6 years of age by 40% due to its very short examination time and its robustness to motion. There is a high level of acceptance among parents and referrers when diagnostic possibilities and limitations are communicated correctly. CONCLUSION: Completely new diagnostic possibilities arise in the imaging of the moving lung, the beating heart, joint movements, and speaking and swallowing, as demonstrated in this video-backed review. WHAT IS KNOWN: • MRI in moving children has been burdened with severe artifacts. • Gross motion usually has to be handled by sedation and periodic motion of the heart and lungs has to be compensated with time-consuming techniques until now. WHAT IS NEW: • Real-time MRI allows image acquisition with up to 50 frames per second similar to ultrasound frame rate. • Real-time MRI proofs to be very promising for imaging children, reducing examination time and sedation rate drastically.

Movement patterns in tuba playing: comparison of an embouchure dystonia case with healthy professional tuba players using real-time MRI imaging.

Introduction: Musculoskeletal problems in professional brass musicians are very common and often involve the muscles of the embouchure. In rare cases, embouchure dystonia (EmD), a task-specific movement disorder with a wide symptomatic and phenotypic variability, occurs. Following trumpeters and horn players, professional tuba players with and without EmD have now been studied using the latest real-time MRI technology to better understand the underlying pathophysiology. Materials and methods: In the present study, the tongue movement patterns of 11 healthy professional artists and one subject suffering from EmD were compared. The tongue position in the anterior, intermediary and posterior oral cavity were converted into pixel positions based on seven previously generated profile lines, using the established software MATLAB. These data allow a structured comparison of tongue movement patterns between the patient and the healthy subjects, as well as between individual exercises. The main focus of the analysis was on an ascending 7-note harmonic series performed in different playing techniques (slurred, tongued, tenuto and staccato). Results: Playing the ascending harmonics, a noticeable ascending tongue movement could be observed in the anterior part of the oral cavity in healthy tubists. In the posterior region, there was a slight decrease in oral cavity space. In the EmD patient, hardly any movement was observed at the tongue apex, but in the middle and posterior regions of the oral cavity there was an increase in size the higher the tone became. These distinct differences are relevant for the characterization and a better understanding of the clinical presentation of EmD. Concerning different playing techniques, it was apparent, that notes played slurred or staccato resulted in a larger oral cavity when compared to notes played tongued or tenuto, respectively. Conclusion: By using real-time MRI videos, the tongue movements of tuba players can be clearly observed and analyzed. The differences between healthy and diseased tuba players demonstrate the great effects of movement disorders in a small area of the tongue. In order to better understand the compensation of this motor control dysfunction, further studies should investigate further parameters of tone production in all brass players with a larger number of EmD patients additional to the observed movement patterns.

Maximum velocity projections within 30 seconds: a combination of real-time three-directional flow MRI and cross-sectional volume coverage.

This work is a proof-of-concept realization of a novel technique for rapid volumetric acquisition, reconstruction, and visualization of three-directional (3dir) flow velocities. The technique combines real-time 3dir phase-contrast (PC) flow magnetic resonance imaging (MRI) with real-time cross-sectional volume coverage. It offers a rapid examination without dependence on electrocardiography (ECG) or respiratory gating during a continuous image acquisition at up to 16 fps. Real-time flow MRI utilizes pronounced radial undersampling and a model-based nonlinear inverse reconstruction. Volume coverage is achieved by automatically advancing the slice position of each PC acquisition by a small percentage of the slice thickness. Post-processing involves the calculation of maximum intensity projections along the slice dimension resulting in six direction-selective velocity maps and a maximum speed map. Preliminary applications to healthy subjects at 3 T comprise mapping of the carotid arteries and cranial vessels at 1.0 mm in-plane resolution within 30 s as well as of the aortic arch at 1.6 mm resolution within 20 s. In conclusion, the proposed method for rapid mapping of 3dir flow velocities offers a quick assessment of the vasculature either to provide a first clinical survey or to plan for more detailed studies.

T1 mapping of the prostate using Single-Shot T1FLASH and MOLLI MRI Techniques: Comparison of artifact burden and image quality.

PURPOSE: To assess artifact burden and image quality of different MRI T1 mapping techniques of the prostate. METHODS: Participants with suspected prostate cancer (PCa) were prospectively enrolled from June-October 2022 and examined with multiparametric prostate MRI (mpMRI; 3 T scanner; T1wi, T2wi, DWI und DCE). T1 mapping was performed before and after administration of gadolinium-based contrast-agent (GBCA) using (i) a modified Look-Locker inversion (MOLLI) technique and (ii) a novel single-shot T1FLASH inversion recovery technique. T2wi, DWI, T1FLASH and MOLLI sequences were systematically examined regarding prevalence of artifacts and image quality using a 5-point Likert-Scale. RESULTS: A total of n = 100 patients were included (median age: 68 years). T1FLASH maps (pre-and post-GBCA) showed metal artifacts in 7% of cases and susceptibility artifacts in 1%. For MOLLI maps, pre-GBCA metal and susceptibility artifacts were documented in 6.5% of cases each. MOLLI maps post-GBCA showed artifacts in 59% of cases resulting primarily from urinary GBCA excretion and GBCA accumulation at the bladder base (p < 0.01 versus T1FLASH post-GBCA). Image quality for T1FLASH pre-GBCA was rated at a mean 4.9+/-0.4 and for MOLLI at 4.8+/-0.6 (p = 0.14). Post-GBCA image quality was rated at a mean 4.9+/-0.4 for T1FLASH and at 3.7+/-1.1 for MOLLI (p < 0.001). CONCLUSIONS: T1FLASH maps provide a fast and robust method for quantification of T1 relaxation times of the prostate. T1FLASH is suitable for T1 mapping of the prostate following administration of contrast agents, while MOLLI T1 mapping is impaired through GBCA accumulation at the bladder base leading to severe image artifacts and reduced image quality.

T1 Mapping of the Prostate Using Single-Shot T1FLASH: A Clinical Feasibility Study to Optimize Prostate Cancer Assessment.

PURPOSE: The aim of this study was to assess the clinical feasibility of magnetic resonance imaging (MRI) T1 mapping using T1FLASH for assessment of prostate lesions. METHODS: Participants with clinical suspicion for prostate cancer (PCa) were prospectively enrolled between October 2021 and April 2022 with multiparametric prostate MRI (mpMRI) acquired on a 3 T scanner. In addition, T1 mapping was accomplished using a single-shot T1FLASH technique with inversion recovery, radial undersampling, and iterative reconstruction. Regions of interest (ROIs) were manually placed on radiologically identified prostate lesions and representative reference regions of the transitional zone (TZ), benign prostate hyperplasia nodules, and peripheral zone (PZ). Mean T1 relaxation times and apparent diffusion coefficient (ADC) values (b = 50/b = 1400 s/mm 2 ) were measured for each ROI. Participants were included in the study if they underwent ultrasound/MRI fusion-guided prostate biopsy for radiologically or clinically suspected PCa. Histological evaluation of biopsy cores served as reference standard, with grading of PCa according to the International Society of Urological Pathology (ISUP). ISUP grades 2 and above were considered clinically significant PCa for the scope of this study. Histological results of prostate biopsy cores were anatomically mapped to corresponding mpMRI ROIs using biopsy plans. T1 relaxation times and ADC values were compared across prostate regions and ISUP groups. Across different strata, T1 relaxation time, ADC values, and diagnostic accuracy (area under the curve [AUC]) were compared using statistical methods accounting for clustered data. RESULTS: Of 67 eligible participants, a total of 40 participants undergoing ultrasound/MRI fusion-guided prostate biopsy were included. Multislice T1 mapping was successfully performed in all participants at a median acquisition time of 2:10 minutes without evident image artifacts. A total of 71 prostate lesions was radiologically identified (TZ 49; PZ 22). Among those, 22 were histologically diagnosed with PCa (ISUP groups 1/2/3/4 in n = 3/15/3/1 cases, respectively). In the TZ, T1 relaxation time was statistically significantly lower for PCa compared with reference regions ( P = 0.029) and benign prostate hyperplasia nodules ( P < 0.001). Similarly, in the PZ, PCa demonstrated shorter T1 relaxation times versus reference regions ( P < 0.001). PCa also showed a trend toward shorter T1 relaxation times (median, 1.40 seconds) compared with radiologically suspicious lesions with benign histology (median, 1.47 seconds), although statistical significance was not reached ( P = 0.066). For discrimination of PCa from reference regions and benign prostate lesions, T1 relaxation times and ADC values demonstrated AUC = 0.80 and AUC = 0.83, respectively ( P = 0.519). Discriminating PCa from radiologically suspicious lesions with benign histology, T1 relaxation times and ADC values showed AUC = 0.69 and AUC = 0.62, respectively ( P = 0.446). CONCLUSIONS: T1FLASH-based T1 mapping yields robust results for quantification of prostate T1 relaxation time at a short examination time of 2:10 minutes without evident image artifacts. Associated T1 relaxation times could aid in discrimination of significant and nonsignificant PCa. Further studies are warranted to confirm these results in a larger patient cohort, to assess the additional benefit of T1FLASH maps in conjunction with mpMRI sequences in the setting of deep learning, and to evaluate the robustness of T1FLASH maps compared with potentially artifact-prone diffusion-weighted imaging sequences.

Comparison of EPI DWI and STEAM DWI in Early Postoperative MRI Controls After Resection of Tumors of the Central Nervous System.

PURPOSE: Diffusion-weighted imaging (DWI) is important for differentiating residual tumor and subacute infarctions in early postoperative magnetic resonance imaging (MRI) of central nervous system (CNS) tumors. In cases of pneumocephalus and especially in the presence of intraventricular trapped air, conventional echo-planar imaging (EPI) DWI is distorted by susceptibility artifacts. The performance and robustness of a newly developed DWI sequence using the stimulated echo acquisition mode (STEAM) was evaluated in patients after neurosurgical operations with early postoperative MRI. METHODS: We compared EPI and STEAM DWI of 43 patients who received 3­Tesla MRI within 72 h after a neurosurgical operation between 1 October 2019 and 30 September 2021. We analyzed susceptibility artifacts originating from air and blood and whether these artifacts compromised the detection of ischemic changes after surgery. The DWI sequences were (i) visually rated and (ii) volumetrically analyzed. RESULTS: In 28 of 43 patients, we found severe and diagnostically relevant artifacts in EPI DWI, but none in STEAM DWI. In these cases, in which artifacts were caused by intracranial air, they led to a worse detection of ischemic lesions and thus to a possible failed diagnosis or lack of judgment using EPI DWI. Additionally, volumetric analysis demonstrated a 14% smaller infarct volume detected with EPI DWI. No significant differences in visual rating and volumetric analysis were detected among the patients without severe artifacts. CONCLUSION: The newly developed version of STEAM DWI with highly undersampled radial encodings is superior to EPI DWI in patients with postoperative pneumocephalus.

FLASHlight MRI in real time-a step towards Star Trek medicine.

This work describes a dynamic magnetic resonance imaging (MRI) technique for local scanning of the human body with use of a handheld receive coil or coil array. Real-time MRI is based on highly undersampled radial gradient-echo sequences with joint reconstructions of serial images and coil sensitivity maps by regularized nonlinear inversion (NLINV). For this proof-of-concept study, a fixed slice position and field-of-view (FOV) were predefined from the operating console, while a local receive coil (array) is moved across the body-for the sake of simplicity by the subject itself. Experimental realizations with a conventional 3 T magnet comprise dynamic anatomic imaging of the head, thorax and abdomen of healthy volunteers. Typically, the image resolution was 0.75 to 1.5 mm with 3 to 6 mm section thickness and acquisition times of 33 to 100 ms per frame. However, spatiotemporal resolutions and contrasts are highly variable and may be adjusted to clinical needs. In summary, the proposed FLASHlight MRI method provides a robust acquisition and reconstruction basis for future diagnostic strategies that mimic the usage of ultrasound. Necessary extensions for this vision require remote control of all sequence parameters by a person at the scanner as well as the design of more flexible gradients and magnets.

Brain deposition of gadobutrol in children-a cross-sectional and longitudinal MRI T1 mapping study.

OBJECTIVES: Depositions of linear gadolinium-based MRI contrast agents are readily visible in T1-weighted MRIs of certain brain regions in both adults and children. Macrocyclic contrast agents such as gadobutrol have so far escaped detection by qualitative MRI in children. This study aimed to assess whether there is evidence for deposition of gadobutrol in children using quantitative T1 mapping. METHODS: This retrospective study included patients, naive to other gadolinium-based contrast agents than gadobutrol, who had received gadobutrol as part of a clinically indicated MRI. For each patient, T1 relaxation times at 3 T were measured using single-shot T1 mapping at two time points. In each of six brain regions, age-adjusted T1 relaxation times were correlated with a number of previous gadobutrol administrations. To combine interindividual, cross-sectional effects with intraindividual, longitudinal effects, both linear mixed model and generalized additive mixed model were applied. RESULTS: One hundred four examinations of 52 children (age median 11.4, IQR 6.3-15, 26 female) with a median of 7 doses of gadobutrol in the history of their neurological or neurooncological disease were included. After correction for age and indeterminate disease-related effects to T1 time, a negative correlation of T1 time with the number of gadobutrol doses administered was observed in both mixed models in the putamen (beta - 1.65, p = .03) and globus pallidus (beta - 1.98, p = .012) CONCLUSIONS: The results indicate that in children, gadobutrol is deposited in the globus pallidus and putamen. KEY POINTS: • Previous gadobutrol administration correlates with reduced T1 relaxation times in the globus pallidus and putamen in children. • This decreased T1 might be caused by gadobutrol retention within these gray-matter nuclei.

Pectus excavatum in motion: dynamic evaluation using real-time MRI.

OBJECTIVES: The breathing phase for the determination of thoracic indices in patients with pectus excavatum is not standardized. The aim of this study was to identify the best period for reliable assessments of morphologic indices by dynamic observations of the chest wall using real-time MRI. METHODS: In this prospective study, patients with pectus excavatum underwent morphologic evaluation by real-time MRI at 3 T between January 2020 and June 2021. The Haller index (HI), correction index (CI), modified asymmetry index (AI), and modified eccentricity index (EI) were determined during free, quiet, and forced breathing respectively. Breathing-related differences in the thoracic indices were analyzed with the Wilcoxon signed-rank test. Motion of the anterior chest wall was analyzed as well. RESULTS: A total of 56 patients (11 females and 45 males, median age 15.4 years, interquartile range 14.3-16.9) were included. In quiet expiration, the median HI in the cohort equaled 5.7 (4.5-7.2). The median absolute differences (Δ) in the thoracic indices between peak inspiration and peak expiration were ΔHI = 1.1 (0.7-1.6, p < .001), ΔCI = 4.8% (1.3-7.5%, p < .001), ΔAI = 3.0% (1.0-5.0%, p < .001), and ΔEI = 8.0% (3.0-14.0%, p < .05). The indices varied significantly during different inspiratory phases, but not during expiration (p > .05 each). Furthermore, the dynamic evaluation revealed three distinctive movement patterns of the funnel chest. CONCLUSIONS: Real-time MRI reveals patterns of chest wall motion and indicate that thoracic indices of pectus excavatum should be assessed in the end-expiratory phase of quiet expiration. KEY POINTS: • The thoracic indices in patients with pectus excavatum depend on the breathing phase. • Quiet expiration represents the best breathing phase for determining thoracic indices. • Real-time MRI can identify different chest wall motion patterns in pectus excavatum.

Chest examinations in children with real-time magnetic resonance imaging: first clinical experience.

BACKGROUND: Real-time magnetic resonance imaging (MRI) based on a fast low-angle shot technique 2.0 (FLASH 2.0) is highly effective against artifacts caused due to the bulk and pulmonary and cardiac motions of the patient. However, to date, there are no reports on the application of this innovative technique to pediatric lung MRI. OBJECTIVE: This study aimed to identify the limits of resolution and image quality of real-time lung MRI in children and to assess the types and minimal size of lesions with these new sequences. MATERIALS AND METHODS: In this retrospective study, pathological lung findings in 87 children were classified into 6 subgroups, as detected on conventional MRI: metastases and tumors, consolidation, scars, hyperinflation, interstitial pathology and bronchiectasis. Subsequently, the findings were grouped according to size (4-6 mm, 7-9 mm and ≥ 10 mm) and evaluated for visual delineation of the findings (0 = not visible, 1 = hardly visible and 2 = well visualized). RESULTS: Real-time MRI allows for diagnostic, artifact-free thorax images to be obtained, regardless of patient movements. The delineation of findings strongly correlates with the size of the pathology. Metastases, consolidation and scars were visible at 100% when larger than 9 mm. In the 7-9 mm subgroup, the visibility was 83% for metastases, 88% for consolidation and 100% for scars in T2/T1 weighting. Though often visible, smaller pathological lesions of 4-6 mm in size did not regularly meet the expected diagnostic confidence: The visibility of metastases was 18%, consolidation was 64% and scars was 71%. Diffuse interstitial lung changes and hyperinflation, known as "MR-minus pathologies," were not accessible to real-time MRI. CONCLUSION: The method provides motion robust images of the lung and thorax. However, the lower sensitivity for small lung lesions is a major limitation for routine use of this technique. Currently, the method is adequate for diagnosing inflammatory lung diseases, atelectasis, effusions and lung scarring in children with irregular breathing patterns or bulk motion on sedation-free MRI. A medium-term goal is to improve the diagnostic accuracy of small nodules and interstitial lesions.

Vowel height and velum position in German: Insights from a real-time magnetic resonance imaging study.

Velum position was analysed as a function of vowel height in German tense and lax vowels preceding a nasal or oral consonant. Findings from previous research suggest an interdependence between vowel height and the degree of velum lowering, with a higher velum during high vowels and a more lowered velum during low vowels. In the current study, data were presented from 33 native speakers of Standard German who were measured via non-invasive high quality real-time magnetic resonance imaging. The focus was on exploring the spatiotemporal extent of velum lowering in tense and lax /a, i, o, ø/, which was done by analysing velum movement trajectories over the course of VN and VC sequences in CVNV and CVCV sequences by means of functional principal component analysis. Analyses focused on the impact of the vowel category and vowel tenseness. Data indicated that not only the position of the velum was affected by these factors but also the timing of velum closure. Moreover, it is argued that the effect of vowel height was to be better interpreted in terms of the physiological constriction location of vowels, i.e., the specific tongue position rather than phonetic vowel height.