Magnetic Resonance Imaging Visualization Research Articles

Arthroscopy has a higher discriminative capacity than MRI in detecting mild cartilage lesions.

To determine whether current magnetic resonance imaging (MRI) could detect superficial cartilage lesions that are observed during diagnostic arthroscopy in patients with knee pain who have not been diagnosed with joint disease. Adult patients with knee pain of unclear origin lasting more than three months, scheduled for a therapeutic/diagnostic arthroscopy were recruited. Demographic and clinical data, pain assessment, MRI imaging, and observations of cartilage damage in the medial femoral condyle during arthroscopic procedure were documented. Patients were categorized based on the presence of cartilage damage assessed via MRI and/or direct visualization. Concordance between these assessments and its variation with age and patient-reported pain were examined. Out of the 95 patients recruited, 48 exhibited lesions in the medial femoral condyle (MFC) during arthroscopic examination, while only 24 of them showed lesions on the MRI scans. The thickness of the cartilage in the MFC was significantly lower in patients with cartilage damage detected by MRI compared with those without. Among patients with cartilage lesions identified during arthroscopy, those also showing lesions on the MRI had lower cartilage thickness and higher Outerbridge score than those without lesions on the MRI. Patients with detectable cartilage damage on the MRI were significantly older and reported higher levels of pain than those with damage detected only by arthroscopic examination. Despite significant technological advancements in MRI, arthroscopy still proves superior in identifying mild structural cartilage lesions that are not identifiable by this technique.

Cationic fluorinated micelles for cell labeling and 19F-MR imaging

Magnetic resonance imaging (MRI) relies on appropriate contrast agents, especially for visualizing transplanted cells within host tissue. In recent years, compounds containing fluorine-19 have gained significant attention as MRI probe, particularly in dual 1H/19F-MR imaging. However, various factors affecting probe sensitivity, such as fluorine content and the equivalency of fluorine atoms, must be considered. In this study, we synthesized fluorinated micelles with adjustable surface positive charge density and investigated their physicochemical properties and MRI efficacy in phantoms and labeled cells. While the micelles exhibited clear signals in 19F-MR spectra and imaging, the concentrations required for MRI visualization of labeled cells were relatively high, adversely affecting cell viability. Despite their favourable physicochemical properties, achieving higher labeling rates without compromising cell viability during labeling remains a challenge for potential in vivo applications.

Probing rotaxane dynamics with 19F NMR/MRI: Unveiling the roles of mechanical bond and steric hindrance

BackgroundDeciphering the molecular dynamics (MD) of rotaxanes is crucial for designing and refining their applications in molecular devices. This study employed fluorine-19 nuclear magnetic resonance (19F NMR) and magnetic resonance imaging (MRI) to unveil the interplay between mechanical bonds and steric hindrance in a series of fluorinated rotaxanes. Results1H/19F NMR revealed stable “Z”-shaped wheel conformations minimizing steric clashes and favoring π-π interactions with the axle. Utilizing fluorines and axle protons as reporters, 1H/19F relaxation rates and solid-state 19F NMR studies demonstrated that mechanical bond primarily governs wheel motion, while steric hindrance dictates axle movement. Intriguingly, mechanical bond mainly affects local axle groups, leaving distant ones minimally impacted. MD simulations corroborated these findings. Temperature-dependent 19F NMR indicated that energy input enhances rotational motion and wheel conformational transitions. Furthermore, the drastic increase in 19F relaxation rates upon mechanical bond formation and steric hindrance enables sensitive and selective 19F MRI visualization of MD changes. SignificanceThis study, by elucidating the roles of internal and external factors on rotaxane molecular dynamics using 19F NMR/MRI, offers valuable insights that can advance the field of rotaxane-based molecular devices.

Use of Magnetic Resonance Imaging for Visualization of Oral Dosage Forms in the Human Stomach: A Scoping Review.

Oral dosage forms are the most widely and frequently used formulations to deliver active pharmaceutical ingredients (APIs), due to their ease of administration and noninvasiveness. Knowledge of intragastric release rates and gastric mixing is crucial for predicting the API release profile, especially for immediate release formulations. However, knowledge of the intragastric fate of oral dosage forms in vivo to date is limited, particularly for dosage forms administered when the stomach is in the fed state. An improved understanding of gastric food processing, dosage form location, disintegration times, and food effects is essential for greater understanding for effective API formulation design. In vitro standard and controlled modeling has played a significant role in predicting the behavior of dosage forms in vivo. However, discrepancies are reported between in vitro and in vivo disintegration times, with these discrepancies being greatest in the fed state. Studying the fate of a dosage form in vivo is a challenging process, usually requiring the use of invasive methods, such as intubation. Noninvasive, whole body imaging techniques can however provide unique insights into this process. A scoping review was performed systematically to identify and critically appraise published studies using MRI to visualize oral solid dosage forms in vivo in healthy human subjects. The review identifies that so far, an all-purpose robust contrast agent or dosage form type has not been established for dosage form visualization and disintegration studies in the gastrointestinal system. Opportunities have been identified for future studies, with particular focus on characterizing dosage form disintegration for development after the consumption food, as exemplified by the standard Food and Drug Administration (FDA) high fat meal.

Characterization and antitumor effect of doxorubicin-loaded Fe3O4-Au nanocomposite synthesized by electron beam evaporation for magnetic nanotheranostics.

Magnetic nanocomposites (MNC) are promising theranostic platforms with tunable physicochemical properties allowing for remote drug delivery and multimodal imaging. Here, we developed doxorubicin-loaded Fe3O4-Au MNC (DOX-MNC) using electron beam physical vapor deposition (EB-PVD) in combination with magneto-mechanochemical synthesis to assess their antitumor effect on Walker-256 carcinosarcoma under the influence of a constant magnetic (CMF) and electromagnetic field (EMF) by comparing tumor growth kinetics, magnetic resonance imaging (MRI) scans and electron spin resonance (ESR) spectra. Transmission (TEM) and scanning electron microscopy (SEM) confirmed the formation of spherical magnetite nanoparticles with a discontinuous gold coating that did not significantly affect the ferromagnetic properties of MNC, as measured by vibrating-sample magnetometry (VSM). Tumor-bearing animals were divided into the control (no treatment), conventional doxorubicin (DOX), DOX-MNC and DOX-MNC + CMF + EMF groups. DOX-MNC + CMF + EMF resulted in 14% and 16% inhibition of tumor growth kinetics as compared with DOX and DOX-MNC, respectively. MRI visualization showed more substantial tumor necrotic changes after the combined treatment. Quantitative analysis of T2-weighted (T2W) images revealed the lowest value of skewness and a significant increase in tumor intensity in response to DOX-MNC + CMF + EMF as compared with the control (1.4 times), DOX (1.6 times) and DOX-MNC (1.8 times) groups. In addition, the lowest level of nitric oxide determined by ESR was found in DOX-MNC + CMF + EMF tumors, which was close to that of the muscle tissue in the contralateral limb. We propose that the reason for the relationship between the observed changes in MRI and ESR is the hyperfine interaction of nuclear and electron spins in mitochondria, as a source of free radical production. Therefore, these results point to the use of EB-PVD and magneto-mechanochemically synthesized Fe3O4-Au MNC loaded with DOX as a potential candidate for cancer magnetic nanotheranostic applications.

H-ferritin-nanocaged gadolinium nanoparticles for ultra-sensitive MR molecular imaging.

Rationale: Magnetic resonance imaging (MRI) is a powerful diagnostic technology by providing high-resolution imaging. Although MRI is sufficiently valued in its resolving morphology, it has poor sensitivity for tracking biomarkers. Therefore, contrast agents are often used to improve MRI diagnostic sensitivity. However, the clinically used Gd chelates are limited in improving MRI sensitivity owing to their low relaxivity. The objective of this study is to develop a novel contrast agent to achieve a highly sensitive tracking of biomarkers in vivo. Methods: A Gd-based nanoprobe composed of a gadolinium nanoparticle encapsulated within a human H-ferritin nanocage (Gd-HFn) has been developed. The specificity and sensitivity of Gd-HFn were evaluated in vivo in tumor-bearing mice and apolipoprotein E-deficient mice (Apoe-/-) by MRI. Results: The Gd-HFn probe shows extremely high relaxivity values (r1 = 549 s-1mM-1, r2 = 1555 s-1mM-1 under a 1.5-T magnetic field; and r1 = 428 s-1mM-1 and r2 = 1286 s-1mM-1 under a 3.0-T magnetic field), which is 175-fold higher than that of the clinically standard Dotarem (Gd-DOTA, r1 =3.13 s-1mM-1) under a 1.5-T magnetic field, and 150-fold higher under a 3.0-T magnetic field. Owing to the substantially enhanced relaxivity values, Gd-HFn achieved a highly sensitive tracking for the tumor targeting receptor of TfR1 and enabled the in vivo MRI visualization of tumors approaching the angiogenic switch. Conclusions: The developed Gd-HFn contrast agent makes MRI a more powerful tool by simultaneously providing functional and morphological imaging information, which paves the way for a new perspective in molecular imaging.

Correction of Spinal Sagittal Alignment after Posterior Lumbar Decompression: Does Severity of Central Canal Stenosis Matter?

This study adopted a retrospective study design. Our study aimed to investigate the impact of central canal stenosis severity on surgical outcomes and lumbar sagittal correction after lumbar decompression. Studies have evaluated sagittal correction in patients with central canal stenosis after lumbar decompression and the association of stenosis severity with worse preoperative sagittal alignment. However, none have evaluated the impact of spinal stenosis severity on sagittal correction. Patients undergoing posterior lumbar decompression (PLD) of ≤4 levels were divided into severe and non-severe central canal stenosis groups based on the Lee magnetic resonance imaging (MRI) grading system. Patients without preoperative MRI or inadequate visualization on radiographs were excluded. Surgical characteristics, clinical outcomes, and sagittal measurements were compared. Multivariate logistic regression was performed to determine the predictors of pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), and pelvic incidence minus lumbar lordosis (PI-LL). Of the 142 patients included, 39 had severe stenosis, and 103 had non-severe stenosis. The mean follow-up duration for the cohort was 4.72 months. Patients with severe stenosis were older, had higher comorbidity indices and levels decompressed, and longer lengths of stay and operative times (p <0.001). Although those with severe stenosis had lower lordosis, lower SS, and higher PI-LL mismatch preoperatively, no differences in Delta LL, SS, PT, or PI-LL were observed between the two groups (p >0.05). On multivariate regression, severe stenosis was a significant predictor of a lower preoperative LL (estimate=-5.243, p =0.045) and a higher preoperative PI-LL mismatch (estimate=6.192, p =0.039). No differences in surgical or clinical outcomes were observed (p >0.05). Severe central lumbar stenosis was associated with greater spinopelvic mismatch preoperatively. Sagittal balance improved in both patients with severe and non-severe stenosis after PLD to a similar degree, with differences in sagittal parameters remaining after surgery. We also found no differences in postoperative outcomes associated with stenosis severity.

Prospective cohort study on mesh shrinkage measured with MRI after robot-assisted minimal invasive retrorectus ventral hernia repair using an iron-oxide-loaded polyvinylidene fluoride mesh

BackgroundMesh-reinforced ventral hernia repair is considered the gold standard treatment for all but the smallest of hernias. Human data on mesh shrinkage in the retrorectus mesh position is lacking. A prospective observational cohort study was performed to measure mesh shrinkage in robot-assisted minimal invasive retrorectus repair of ventral hernias.MethodsA cohort of 20 patients underwent a robot-assisted minimal invasive retrorectus repair of their ventral hernia. Magnetic resonance imaging (MRI) imaging was performed one month and thirteen months after implantation of an iron-oxide-impregnated polyvinylidene fluoride (PVDF) mesh to assess the decrease in mesh surface area. Inter-rater reliability among three radiologists regarding measurement of the mesh dimensions was analyzed. Quality of Life scoring was evaluated.ResultsThe inter-rater reliability between the radiologists reported as the intra-class correlations proved to be excellent for mesh width (ICC 0.95), length (ICC 0.98) and surface area (ICC 0.99). Between MRI measurements at one month and thirteen months postoperatively, there was a significant increase in mesh surface area (+ 12.0 cm2, p = 0.0013) and mesh width (+ 0.8 cm, p < 0.001), while the length of the mesh remained unchanged (−0.1 cm, p = 0.754). Quality of Life Scoring showed a significant improvement in Quality of Life after one month and a further improvement at thirteen months (p < 0.001).ConclusionThere was an excellent inter-rater reliability between three radiologists when measuring width, length, and surface area of an iron-oxide-impregnated PVDF mesh using MRI visualization. Mesh shrinkage was not observed, instead the effective mesh surface area and width of the mesh increased.

P-076 PROSPECTIVE COHORT STUDY ON MESH SHRINKAGE MEASURED WITH MRI AFTER ROBOT ASSISTED MINIMAL INVASIVE RETRORECTUS VENTRAL HERNIA REPAIR USING AN IRON OXIDE LOADED PVDF MESH

Abstract Aim Mesh-reinforced ventral hernia repair is considered the gold standard treatment for all but the smallest of hernias. Human data on mesh shrinkage in the retrorectus mesh position is lacking. A prospective observational cohort study was performed to measure mesh shrinkage in robot assisted minimal invasive retrorectus repair of ventral hernias. Methods A cohort of 20 patients underwent a robot assisted minimal invasive retrorectus repair of their ventral hernia. Magnetic resonance imaging (MRI) imaging was performed one month and thirteen months after implantation of an iron-oxide-impregnated polyvinylidene fluoride (PVDF) mesh to assess the decrease in mesh surface area. Inter-rater reliability among three radiologists regarding measurement of the mesh dimensions was analyzed. Quality of Life scoring was evaluated. Results The inter-rater reliability between the radiologists reported as the intra-class correlations proved to be excellent for mesh width (ICC 0.95), length (ICC 0.98) and surface area (ICC 0.99). Between MRI measurements at one month and thirteen months postoperatively, there was a significant increase in mesh surface area (+12.0 cm2, p=0.0013) and mesh width (+0.8 cm, p&amp;lt;0.001), while the length of the mesh remained unchanged (-0.1 cm, p=0.754). Quality of Life Scoring showed a significant improvement in Quality of Life after one month and a further improvement at thirteen months (p&amp;lt;0.001). Conclusion There was an excellent inter-rater reliability between three radiologists when measuring width, length and surface area of an iron-oxide-impregnated PVDF mesh using MRI visualization. Mesh shrinkage was not observed, instead the effective mesh surface area and width of the mesh increased.

Magnetic resonance syndromes of myocardial damage in patients after new coronavirus infection (COVID-19) – two typical clinical cases

Clinical examples for variants of cardiovascular complications of a new coronavirus infection (COVID-19) are presented when they are visualized by means of magnetic resonance imaging (MRI) of the heart and chest organs with paramagnetic contrast enhancement and synchronization with ECG and respiration signal. The syndromes of post-COVID focal infarct injury and diffuse inflammatory lesion are identified. The picture of MRI visualization of coronary atherosclerotic plaque is presented. The results of quantitative processing of cardiac MRI in these two different syndromes of post-COVID cardiological complications are presented. The presented clinical examples indicate the need for cardiac MRI to monitor patients and assess the long-term cardiovascular effects of COVID-19.

A System for Real-Time, Online Mixed-Reality Visualization of Cardiac Magnetic Resonance Images.

Image-guided cardiovascular interventions are rapidly evolving procedures that necessitate imaging systems capable of rapid data acquisition and low-latency image reconstruction and visualization. Compared to alternative modalities, Magnetic Resonance Imaging (MRI) is attractive for guidance in complex interventional settings thanks to excellent soft tissue contrast and large fields-of-view without exposure to ionizing radiation. However, most clinically deployed MRI sequences and visualization pipelines exhibit poor latency characteristics, and spatial integration of complex anatomy and device orientation can be challenging on conventional 2D displays. This work demonstrates a proof-of-concept system linking real-time cardiac MR image acquisition, online low-latency reconstruction, and a stereoscopic display to support further development in real-time MR-guided intervention. Data are acquired using an undersampled, radial trajectory and reconstructed via parallelized through-time radial generalized autocalibrating partially parallel acquisition (GRAPPA) implemented on graphics processing units. Images are rendered for display in a stereoscopic mixed-reality head-mounted display. The system is successfully tested by imaging standard cardiac views in healthy volunteers. Datasets comprised of one slice (46 ms), two slices (92 ms), and three slices (138 ms) are collected, with the acquisition time of each listed in parentheses. Images are displayed with latencies of 42 ms/frame or less for all three conditions. Volumetric data are acquired at one volume per heartbeat with acquisition times of 467 ms and 588 ms when 8 and 12 partitions are acquired, respectively. Volumes are displayed with a latency of 286 ms or less. The faster-than-acquisition latencies for both planar and volumetric display enable real-time 3D visualization of the heart.

Nonsedated Magnetic Resonance Imaging for Visualization of the Velopharynx in the Pediatric Population.

Non-sedated MRI is gaining traction in clinical settings for visualization of the velopharynx in children with velopharyngeal insufficiency. However, the behavioral adaptation and training aspects that are essential for successful pediatric MRI have received limited attention. We outline a program of behavioral modifications combined with patient education and provider training that has led to high success rates for non-sedated velopharyngeal MRI in children.

Improving Blood Flow Visualization of Recirculation Regions at Carotid Bulb in 4D Flow MRI Using Semi-Automatic Segmentation with ITK-SNAP.

Assessment of carotid bulb hemodynamics using four-dimensional (4D) flow magnetic resonance imaging (MRI) requires accurate segmentation of recirculation regions that is frequently hampered by limited resolution. This study aims to improve the accuracy of 4D flow MRI carotid bulb segmentation and subsequent recirculation regions analysis. Time-of-flight (TOF) MRI and 4D flow MRI were performed on bilateral carotid artery bifurcations in seven healthy volunteers. TOF-MRI data was segmented into 3D geometry for computational fluid dynamics (CFD) simulations. ITK-SNAP segmentation software was included in the workflow for the semi-automatic generation of 4D flow MRI angiographic data. This study compared the velocities calculated at the carotid bifurcations and the 3D blood flow visualization at the carotid bulbs obtained by 4D flow MRI and CFD. By applying ITK-SNAP segmentation software, an obvious improvement in the 4D flow MRI visualization of the recirculation regions was observed. The 4D flow MRI images of the recirculation flow characteristics of the carotid artery bulbs coincided with the CFD. A reasonable agreement was found in terms of velocity calculated at the carotid bifurcation between CFD and 4D flow MRI. However, the dispersion of velocity data points relative to the local errors of measurement in 4D flow MRI remains. Our proposed strategy showed the feasibility of improving recirculation regions segmentation and the potential for reliable blood flow visualization in 4D flow MRI. However, quantitative analysis of recirculation regions in 4D flow MRI with ITK-SNAP should be enhanced for use in clinical situations.

Menisco-fibular ligament - an overview: cadaveric dissection, clinical and magnetic resonance imaging diagnosis, arthroscopic visualisation and treatment.

Injury to the menisco-fibular ligament (MFiL) is not commonly recognised. The anatomy of the lateral meniscus is complex and structure-function relationships are only partly understood. The purpose of the present study was to evaluate the MFiL, an anatomic structure rarely discussed that stabilises the lateral meniscus at the level of the hiatus popliteus and may have a crucial role in pathology of lateral meniscus injury. The MFiL was dissected from its attachment at the lateral meniscus to its insertion on fibular head in 12 human normal cadaver knees. The dimensions were determined and its anatomic position visualised throughout a 90° range of motion. Findings were documented on digital photographs and on video. Results were compared against the magnetic resonance imaging (MRI) appearance of the injured MFiL in 20 patients. Concomitant knee injuries in those patients were also analysed to determine the most frequent pattern of injuries. The normal MFiL showed an inverted trapezoid-shape with a mean width proximally of 13 mm, mean width distally of 8.5 mm and a mean length of 18.4 mm. MRI visualisation of the ligament was possible even in regular sequences; however, additional radial plane sequences were also used. Arthroscopic visualisation and manipulation was optimal when the camera was inserted into the postero-lateral gutter with full knee extension. The MFiL stabilises the postero-lateral knee in concert with the menisco-femoral ligaments. Injury to the MFiL can be a cause of chronic postero-lateral pain syndrome with associated instability. Further anatomical and biomechanical studies are needed in order to fully evaluate its importance.

3D MRI of the Ankle: A Concise State-of-the-Art Review.

Magnetic resonance imaging (MRI) is a powerful imaging modality for visualizing a wide range of ankle disorders that affect ligaments, tendons, and articular cartilage. Standard two-dimensional (2D) fast spin-echo (FSE) and turbo spin-echo (TSE) pulse sequences offer high signal-to-noise and contrast-to-noise ratios, but slice thickness limitations create partial volume effects. Modern three-dimensional (3D) FSE/TSE pulse sequences with isotropic voxel dimensions can achieve higher spatial resolution and similar contrast resolutions in ≤ 5 minutes of acquisition time. Advanced acceleration schemes have reduced the blurring effects of 3D FSE/TSE pulse sequences by affording shorter echo train lengths. The ability for thin-slice partitions and multiplanar reformation capabilities eliminate relevant partial volume effects and render modern 3D FSE/TSE pulse sequences excellently suited for MRI visualization of several oblique and curved structures around the ankle. Clinical efficiency gains can be achieved by replacing two or three 2D FSE/TSE sequences within an ankle protocol with a single isotropic 3D FSE/TSE pulse sequence. In this article, we review technical pulse sequence properties for 3D MRI of the ankle, discuss practical considerations for clinical implementation and achieving the highest image quality, compare diagnostic performance metrics of 2D and 3D MRI for major ankle structures, and illustrate a broad spectrum of ankle abnormalities.

Ablative 5-Fraction Stereotactic Magnetic Resonance–Guided Radiation Therapy With On-Table Adaptive Replanning and Elective Nodal Irradiation for Inoperable Pancreas Cancer

PurposeRadiation therapy dose escalation using stereotactic body radiation therapy may significantly improve both local control (LC) and overall survival (OS) for patients with inoperable pancreas cancer. However, ablative dose cannot be routinely offered because of the risk of causing severe injury to adjacent normal organs. Stereotactic magnetic resonance (MR)-guided adaptive radiation therapy (SMART) represents a novel technique that may achieve safe delivery of ablative dose and improve long-term outcomes. Methods and MaterialsWe performed a single institution retrospective analysis of 35 consecutive pancreatic cancer patients treated with SMART in mid-inspiration breath hold on an MR-linear accelerator. Most had locally advanced disease (80%) and received induction chemotherapy (91.4%) for a median 3.9 months before stereotactic body radiation therapy. All were prescribed 5 fractions delivered in consecutive days to a median total dose of 50 Gy (BED10 100 Gy10), typically with a 120% to 130% hotspot. Elective nodal irradiation was delivered to 20 (57.1%) patients. No patient had fiducial markers placed and all were treated with continuous intrafraction MR visualization and automatic beam triggering. ResultsWith median follow-up of 10.3 months from SMART, acute (2.9%) and late (2.9%) grade 3 toxicities were uncommon. One-year LC, distant metastasis-free survival, progression-free survival, cause-specific survival, and OS were 87.8%, 63.1%, 52.4%, 77.6%, and 58.9%, respectively. ConclusionsTo our knowledge, this is the first report of 5-fraction pancreas SMART delivered on an MR-linear accelerator. We observed minimal severe treatment-related toxicity and encouraging early LC. Prospective confirmation of feasibility and long-term clinical outcomes of dose intensified SMART is warranted.

MRI visualization of shiitake mycelium growing in logs in order to support shiitake mushroom log cultivation

In order to correlate the yield and quality of shiitake mushrooms with the growth process of shiitake mycelium in logs over several years, a non-invasive visualization method using a magnetic resonance imaging (MRI) measurement system was developed. The MRI measurement system had a permanent magnet of 1.0 T magnetic field strength and a 110 mm air gap. The test logs in which grew the shiitake mycelium had a diameter of 43–48 mm, a length of 110–118 mm and a dried mass of 125–135 g. The log was inoculated on one cutting surface after being supplied water, and was placed in a thermostatic chamber (21 °C, about 75% humidity) for 69 days. The test log was observed by MRI, and MR images and T1 maps of shiitake mycelium growing over time were obtained. It was found that the shiitake mycelium has a T1 relaxation time constant longer than 150–200 ms, and its signal intensity in the MR images is smaller than that of water penetrated into a log. When making the MRI measurements, it is necessary to dry a log to water content of about 20% or less. In addition, a control log with mold was also observed by MRI. The shiitake mycelium can be distinguished from water penetrated into log and mold occurring in the log by combining the T1—signal intensity map and clear recognition of a low-intensity region in MR images acquired at longer echo times.

Optimal target b-value on computed diffusion-weighted magnetic resonance imaging for visualization of pancreatic ductal adenocarcinoma and focal autoimmune pancreatitis.

To compare computed diffusion-weighted imaging (cDWI) feasibility with that of directly acquired DWI for visualizing pancreatic ductal adenocarcinoma (PDAC) and focal autoimmune pancreatitis (AIP). From April 2012 to January 2017, 135 patients with PDAC (n=111) or focal AIP (n=24) were retrospectively enrolled. They underwent DWI with b-values of 0, 500, and 1000 s/mm2. From DWI0 and DWI1000, we generated cDWIs with targeted b-values of 1500, 2000, and 3000 s/mm2. The lesions' signal intensities, image quality, signal intensity ratio (SIR) of lesions and pancreatic parenchyma to spinal cord, and lesion-to-pancreatic parenchyma contrast ratio (CR) were compared among the five DWI protocols (DWI500, DWI1000, cDWI1500, cDWI2000, and cDWI3000). SIR was analyzed by receiver operating characteristic (ROC) analyses. DWI500, DWI1000, and cDWI1500 had higher image quality than cDWI2000 and cDWI3000 (P < 0.001). The incidence of clear hyperintense PDAC was highest on cDWI2000, followed by cDWI1500, and cDWI3000 (P < 0.001-0.002), while the incidence of clear hyperintense AIP was higher on DWI1000, cDWI1500, and cDWI2000 than on DWI500 and cDWI3000 (P = 0.001-0.022). SIRs decreased whereas CRs increased as the b-value increased, for both PDAC and AIP. The area under the ROC curve (AUC) of SIRlesion was significantly lower on cDWI1500 than on cDWI2000 and cDWI3000 (P < 0.001). cDWI1500 or cDWI2000 generated from b-values of 0 and 1000 s/mm2 were the most effective for visualizing PDAC and focal AIP; however, the SIRlesion AUC was significantly lower on cDWI1500 than on cDWI2000 and cDWI3000.

Magnetic resonance imaging-guided disc-condyle relationship adjustment via articulation: a technical note and case series.

A normal disc–condyle relationship is crucial to the health and function of the temporomandibular joint. We herein introduce a novel technique that can precisely and rapidly restore the disc–condyle relationship. An initial bite rim was made, and the patient was instructed to wear this bite rim during magnetic resonance imaging (MRI) scanning. A quick MRI scan was performed, and the disc–condyle relationship and direction and vector of the displacement was measured. Adjustments to the mandible position were made on an articulator based on the measurements, after which a second bite rim was made. A second quick preview MRI scan was immediately performed, and the images were evaluated and measured again. Additional adjustments were made as needed, and the preview scan was repeated until an ideal disc–condyle relationship was achieved. Once a good disc–condyle relationship was acquired, the mandible position was recorded as the treatment mandible position, and a splint was fabricated. MRI visualization enabled precise and very fine adjustment of the disc–condyle relationship by articulating. This technique might help to simplify the clinical process and improve treatment effectiveness.

Fluorinated Water-Soluble Poly(2-oxazoline)s as Highly Sensitive 19F MRI Contrast Agents

Recently, 19F magnetic resonance imaging (MRI) emerged as a powerful noninvasive diagnostic tool in modern medicine. Fluorinated polymer materials represent an attractive class of MRI contrast agents (CAs) due to their structural variability and tunable properties. Herein, we describe for the first time the 19F MRI of CAs based on fluorinated water-soluble poly(2-oxazoline)s (PAOx), a polymer class with increasing popularity in biomedical sciences. A series of fluorinated PAOx with increasing fluorine content were synthesized by controlled side-chain hydrolysis of poly(2-methyl-2-oxazoline) followed by reacylation of its ethylenimine units by difluoroacetic anhydride. As the increasing fluorine content leads to the copolymer hydrophobization, their composition was optimized for maximal 19F MRI performance while retaining good solubility in water. The magnetic properties of the water-soluble polymers were studied in vitro by 19F NMR and MRI, revealing their outstanding relaxation properties and imaging sensitivity. All CAs were found to be noncytotoxic for HeLa cells in vitro. Finally, the diagnostic potential of the new CAs was demonstrated by a successful in vivo 19F MRI visualization of the selected fluorinated polymer in rats.