Three-Tesla Magnetic Resonance Research Articles

Three-Tesla Magnetic Resonance Imaging Characteristics of Hypertrophic Cardiomyopathy: A Comparison with Several Echocardiography Parameters.

Hypertrophic cardiomyopathy (HCM) is a primary cardiac disorder characterized by myocardial hypertrophy without increased afterload. This study set out to describe the cardiac magnetic resonance (CMR) imaging characteristics of HCM and to evaluate correlations of selected CMR parameters with echocardiography. This cross-sectional study enrolled 46 patients diagnosed at the Vietnam Heart Institute with HCM and underwent CMR at the Radiology Center, Bach Mai Hospital, from July 2021 to September 2022. A left ventricular outflow tract (LVOT)/aortic valve (AO) diameter ratio of ≥0.38 on CMR was consistent with an LVOT pressure gradient (PG) of <30 mmHg on echocardiography. The LVOT diameter and the LVOT/AO diameter ratio differed significantly between obstructive and non-obstructive HCM. The predominant phenotypes were diffuse asymmetric HCM (32.6%) and septal HCM (37%), followed by apical HCM (6.5%). Most late gadolinium enhancement (LGE) lesions were observed in the mid-wall of the hypertrophic segments. The mean LGE mass was significantly higher in the obstructive group than in the non-obstructive HCM group (p < 0.05). A strong negative correlation (r = -0.66) was found between the LVOT/AO diameter ratio on the CMR and the LVOT PG via echocardiography. Moreover, echocardiography detected morphologic risk factors for sudden cardiac death (SCD) in 80.4% of patients, whereas the corresponding proportion detected by CMR was 91.3%. Patients with systolic anterior motion (SAM) had a risk for a LVOT/AO diameter ratio <0.38, which was 5.7 times the risk observed in their counterparts without SAM. The LVOT/AO diameter ratio detected by CMR is a precise index for classifying hemodynamic HCM groups. CMR was better than echocardiography for SCD risk stratification.

Non-invasive Assessment of Microstructural Changes After CyberKnife Radiosurgery for Trigeminal Neuralgia Using Diffusion Tensor Imaging

Background and Aims: Given the absence of a universally accepted non-invasive and objective clinical tool to predict a patient’s response to stereotactic radiosurgery for Trigeminal Neuralgia (TN), this research endeavoured to appraise the potential of Diffusion Tensor Imaging as a predictive tool in managing TN. Objective: This study aimed to assess microstructural changes in the trigeminal nerve following CyberKnife radiosurgery (CKRS) for TN using diffusion tensor imaging (DTI) and to correlate these changes with clinical outcomes. Methods: Twenty-eight TN patients treated with CKRS underwent pre and 4-month post-treatment Three-Tesla magnetic resonance imaging scans with DTI metrics, including fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD), were collected. Clinical outcomes were assessed using the Barrow Neurological Institute Pain Intensity Score (BNI-PIS) at fourth, sixth and ninth months post-CKRS. Results: Twenty-four patients reported good pain relief (responders), while four patients did not experience adequate relief (non-responders). Responders exhibited significantly lower FA (mean drop of 13.8%, P &lt; .001) and lower RA (mean drop of 16.1%, P &lt; .001) compared to non-responders. RD, AD and MD remained constant across the study cohort. Conclusion: DTI metrics, particularly FA and RA, at 4 months post-CKRS, emerged as predictors of long-term treatment effectiveness for TN. These findings suggest the potential utility of DTI in evaluating microstructural changes in the trigeminal nerve post-CKRS and predicting clinical outcomes.

Ex Vivo Comparison of the Diagnostic Performance of Two-Dimensional and Three-Dimensional Three-Tesla Magnetic Resonance Imaging Sequences in Depicting Normal Articular Cartilage in Equine Stifle Cadavers.

The objective of this study was to compare articular cartilage thickness observed in the different 2D and 3D sequences to the cartilage thickness of the equine stifle in cadavers to determine the accuracy of each sequence. The study was conducted as a blinded laboratory study using seven equine stifle specimens. The 2D (T2W TSE) and 3D (3D VIEW T2W HR, T2 3D mFFE, T1W VISTA SPAIR, 3D PDW SPAIR) 3-tesla MRI sequences of each stifle were obtained. Cartilage thickness was measured at 30 locations on MRI and on gross pathology. Thickness measurements were compared using a Bland-Altman plot and post hoc analysis tests. The 3D sequences were found to be generally more accurate than the 2D sequence (p < 0.001). The smallest difference to macroscopic measurements was observed in the 3D VIEW T2W HR and T1W VISTA SPAIR sequences with no statistical difference between each other. Knowing the accuracy of different sequences will improve the evaluation of equine cartilage and the early detection of cartilage pathologies. This would promote MRI as a noninvasive imaging modality for horses suffering from stifle lameness with no findings in conventional imaging methods. Furthermore, since 3D sequences seem to have better accuracy in depicting cartilage, they may replace 2D sequences, thereby shortening scanning times.

Three-Tesla magnetic resonance imaging of left ventricular volume and function in comparison with computed tomography and echocardiography.

This study investigated the correlation between 3-Tesla magnetic resonance imaging (MRI) and 256 multiple-slice computed tomography (MSCT) or 2-dimensional echocardiography (ECHO) in evaluating left ventricle. Forty patients were retrospectively enrolled to undergo cardiac MSCT, 3-Tesla MRI and 2-dimensional ECHO within 1 week. The end-diastolic (EDV) and end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) were analyzed and compared. MSCT was highly significantly correlated with MRI. Compared with MRI, MSCT slightly overestimated ESV for about 8.7 mL, but slightly underestimated EF and SV for about 6.8% and 5.8 mL, respectively. A high consistency existed between MSCT and MRI, with the 95% limit of agreement (-19.6, 25.4) mL for EDV, (-2.6,20.1) mL for ESV, (-28.3,16.6) mL for SV, and (-18.8%,5.1) % for EF. ECHO was also significantly correlated with MRI. The ECHO slightly underestimated the left ventricular function compared with MRI, with an underestimation of 9.4 mL for EDV, 3.5 mL for ESV, 5.8 mL for SV and 1.0% for EF. A wider agreement limit existed between MRI and ECHO. MSCT has a better correlation and agreement relationship with MRI parameters than 2-dimensional ECHO in assessing the left ventricle and may serve as a possible alternative to MRI.

Factors affecting global neurocognitive status and frontal executive functions in the early stage after surgical clipping of unruptured anterior circulation aneurysms with respect to keyhole clipping and conventional clipping.

This study investigated the most significant factor for the preservation of the global neurocognitive status and frontal executive functions in the surgical clipping of unruptured anterior circulation aneurysms, specifically in keyhole and conventional clipping procedures. The prospective study that was performed to examine the effects of aneurysm surgery on the patient's global neurocognitive status and frontal executive functions started on April 2016. After exclusion posterior circulation aneurysms, anterior communicating aneurysms treated by interhemispheric approach, giant aneurysms, and paraclinoid aneurysms, 23 patients who were enrolled before May 2017 were treated by conventional clipping, and 18 patients who were enrolled after June 2017 were treated by keyhole clipping. Two patients were excluded from each group due to missing data. Finally, 21 and 16 patients in each group were analyzed, respectively. Three-tesla magnetic resonance imaging was performed before and after surgery to detect the presence of perioperative cerebral infarctions and brain edema. The Mini-Mental State Examination, Frontal Assessment Battery, and Self-Rating Depression Scale scores were obtained before and 1month after surgery. Logistic regression analyses indicated that anterior communicating and internal carotid artery aneurysms were the most significant factors for poor outcomes and that keyhole clipping for these two types of aneurysm was the most significant factor for the preservation of patient global neurocognitive status. Keyhole clipping was also the most significant factor for the preservation of frontal executive functions in patients. Keyhole clipping may be more favorable than conventional clipping for the preservation of the global neurocognitive status and frontal executive functions. Moreover, it may be the most effective factor for preservation of global neurocognitive status when it is indicated for anterior communicating or internal carotid artery aneurysms.

31-Phosphorus Magnetic Resonance Spectroscopy in Evaluation of Glioma and Metastases in 3T MRI.

Background: 31-Phosphorus magnetic resonance spectroscopy (31-P MRS) has excellent potential for clinical neurological practice because of its noninvasive in-vivo assessment of cellular energy metabolism and the indirect evaluation of the phospholipid composition of the cell membrane, intracellular pH, and intracellular Mg2+ concentration. Purpose: The aim of this study was to evaluate the metabolic characteristics of glioma and metastases using 31-P MRS and assess utility to differentiate both. Study Type: Prospective study. Population: Fifteen consecutive patients with brain tumor. Field Strength/Sequence: Three-tesla magnetic resonance imaging/three-dimensional MRS imaging sequence. Statistical Tests: Unpaired sample t -test, and one-way analysis of variance with Tukey's post-hoc test. Results: Significantly decreased values of phosphomonoesters/inorganic phosphate (PME/Pi) in the tumor group (1.22 ± 0.72) compared with controls (2.28 ± 1.44) with a p -value of 0.041 were observed. There is a significant decrease in phosphocreatine (PCr)/Pi values (energy demand) in the tumor group (2.76 ± 0.73) compared with controls (4.13 ± 1.75) with a p -value of 0.050. Significant increase in Pi/adenosine triphosphate (ATP) was noted in tumor group (0.28 ± 0.09) compared with controls (0.22 ± 0.08) with p -value 0.049. Among tumor group, PME/PCr values were significantly decreased in gliomas (0.35 ± 0.17) than metastasis (0.58 ± 0.23) compared with controls with a p -value of 0.047. A significant decrease in PME/ATP was noted in gliomas (0.25 ± 0.12) than metastasis (0.41 ± 0.14) compared with controls with a p -value of 0.034. The tumor group exhibits alkaline pH (7.12 ± 0.10) compared with the normal parenchyma (7.04 ± 0.06) with a significant p -value of 0.025. Glioma and metastasis could not be differentiated with pH. However, the perilesional edema of glioma shows alkaline pH (7.09 ± 0.06) and metastasis shows acidic pH (7.02 ± 0.05) with a significant p -value of 0.030. Conclusion: Our study provides new insight into the cellular constituents and pH of gliomas and metastases and results were significant in differentiation between these two. However, due to the additional high expense, it is available as a research tool in very few institutions in India.

Three-Tesla Magnetic Resonance Imaging of Patients With Deep Brain Stimulators: Results From a Phantom Study and a Pilot Study in Patients.

Deep brain stimulation (DBS) is a standard of care treatment for multiple neurologic disorders. Although 3-tesla (3T) magnetic resonance imaging (MRI) has become the gold-standard modality for structural and functional imaging, most centers refrain from 3T imaging in patients with DBS devices in place because of safety concerns. 3T MRI could be used not only for structural imaging, but also for functional MRI to study the effects of DBS on neurocircuitry and optimize programming. To use an anthropomorphic phantom design to perform temperature and voltage safety testing on an activated DBS device during 3T imaging. An anthropomorphic 3D-printed human phantom was constructed and used to perform temperature and voltage testing on a DBS device during 3T MRI. Based on the phantom assessment, a cohort study was conducted in which 6 human patients underwent MRI with their DBS device in an activated (ON) state. During the phantom study, temperature rises were under 2°C during all sequences, with the DBS in both the deactivated and activated states. Radiofrequency pulses from the MRI appeared to modulate the electrical discharge from the DBS, resulting in slight fluctuations of voltage amplitude. Six human subjects underwent MRI with their DBS in an activated state without any serious adverse events. One patient experienced stimulation-related side effects during T1-MPRAGE scanning with the DBS in an ON state because of radiofrequency-induced modulation of voltage amplitude. Following careful phantom-based safety testing, 3T structural and functional MRI can be safely performed in subjects with activated deep brain stimulators.

Quadriceps muscle volume positively contributes to ACL volume.

Females have smaller anterior cruciate ligaments (ACLs) than malesand smaller ACLs have been associated with a greater risk of ACL injury. Overall body dimensions do not adequately explain these sex differences. This study examined the extent to which quadriceps muscle volume (VOLQUAD ) positively predicts ACL volume (VOLACL ) once sex and other body dimensions were accounted for. Physically active males (N = 10) and females (N = 10) were measured for height, weight, and body mass index (BMI). Three-Teslamagnetic resonanceimages of their dominant and nondominant thigh and knee were then obtained to measure VOLACL , quadriceps, and hamstring muscle volumes, femoral notch width, and femoral notch width index. Separate three-step regressions estimated associations between VOLQUAD and VOLACL (third step), after controlling for sex (first step) and one body dimension (second step). When controlling for sex and sex plus BMI, VOLHAM , notch width, or notch width index, VOLQUAD consistently exhibited a positive association with VOLACL in the dominant leg, nondominant leg, and leg-averaged models (p < 0.05). Findings were inconsistent when controlling for sex and height (p = 0.038-0.102). Once VOLQUAD was included, only notch width and notch width index retained a statistically significant individual association with VOLACL (p < 0.01). Statement of Clinical Significance: The positive association between VOLQUAD and VOLACL suggests ACL size may in part be modifiable. Future studies are needed to determine the extent to which an appropriate training stimulus (focused on optimizing overall lower extremity muscle mass development) can positively impact ACL size and structure in young females.

Defining the proximity of the axillary nerve from defined anatomic landmarks: an in vivo magnetic resonance imaging study

The location of the axillary nerve in the shoulder makes it vulnerable to traumatic or iatrogenic injury. Cadaveric studies have reported the location of the axillary nerve but are limited because of tissue compression, dehydration, and decay. Three-Tesla (T) magnetic resonance imaging (MRI) allows high anatomic resolution of neural structures. The aim of our study was to better define the location of the axillary nerve from defined bony surgical landmarks invivo, using MRI scan. Using MRI, we defined a number of anatomic points and measured the distance from these to the perineural fat surrounding the axillary nerve using simultaneous tracker lines on both images. Two observers were used. A total of 187 consecutive 3-T MRI shoulder scans were included. Mean age was 57.9 years (range 18-86). The axillary nerve was located at a mean of 14.1 mm inferior from the bony glenoid at the anterior border, 11.9 mm from the midpoint, and 12.0 mm from the posterior border. There was a significant difference between distance at the anterior border and midpoint (P < .001), and between the anterior and posterior borders (P < .001). The axillary nerve was located at a mean of 12.6 mm medial to the humeral shaft at the anterior border, 9.9 mm at the midpoint, and 8.6 mm from the posterior border. There was a significant difference between distance at the anterior border and midpoint (P = .008) and between the anterior and posterior borders (P = .002). The mean distance of the axillary nerve from the anterolateral edge of the acromion was 53.3 mm (95% confidence interval [CI] 52.3, 54.2; range 33.9-76.3). The mean distance of the axillary nerve from the inferior edge of the capsule was 2.7 mm (95% CI 2.9, 3.1; range 0.3-9.9). There was a positive correlation between humeral head diameter and axillary nerve distance from the inferior glenoid (R2 = 0.061, P < .001). There was a positive correlation between humeral head diameter and distance from the anterolateral edge of the acromion (R2 = 0.140, P < .001). Our study has defined the proximity of the axillary nerve from defined anatomic landmarks. The proximity of the axillary nerve to the inferior glenoid and medial humeral shaft changes as the axillary nerve passes from anterior to posterior. The distance of the axillary nerve from the anterolateral edge of the acromion remains relatively constant. Both sets of distances may be affected by humeral head size. The study has relevance to the shoulder surgeon when considering "safe zones" during arthroscopic or open surgery.

Association of Adverse Outcomes With Emotion Processing and Its Neural Substrate in Individuals at Clinical High Risk for Psychosis

The development of adverse clinical outcomes in patients with psychosis has been associated with behavioral and neuroanatomical deficits related to emotion processing. However, the association between alterations in brain regions subserving emotion processing and clinical outcomes remains unclear. To examine the association between alterations in emotion processing and regional gray matter volumes in individuals at clinical high risk (CHR) for psychosis, and the association with subsequent clinical outcomes. This naturalistic case-control study with clinical follow-up at 12 months was conducted from July 1, 2010, to August 31, 2016, and collected data from 9 psychosis early detection centers (Amsterdam, Basel, Cologne, Copenhagen, London, Melbourne, Paris, The Hague, and Vienna). Participants (213 individuals at CHR and 52 healthy controls) were enrolled in the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions (EU-GEI) project. Data were analyzed from October 1, 2018, to April 24, 2019. Emotion recognition was assessed with the Degraded Facial Affect Recognition Task. Three-Tesla magnetic resonance imaging scans were acquired from all participants, and gray matter volume was measured in regions of interest (medial prefrontal cortex, amygdala, hippocampus, and insula). Clinical outcomes at 12 months were evaluated for transition to psychosis using the Comprehensive Assessment of At-Risk Mental States criteria, and the level of overall functioning was measured through the Global Assessment of Functioning [GAF] scale. A total of 213 individuals at CHR (105 women [49.3%]; mean [SD] age, 22.9 [4.7] years) and 52 healthy controls (25 women [48.1%]; mean [SD] age, 23.3 [4.0] years) were included in the study at baseline. At the follow-up within 2 years of baseline, 44 individuals at CHR (20.7%) had developed psychosis and 169 (79.3%) had not. Of the individuals at CHR reinterviewed with the GAF, 39 (30.0%) showed good overall functioning (GAF score, ≥65), whereas 91 (70.0%) had poor overall functioning (GAF score, <65). Within the CHR sample, better anger recognition at baseline was associated with worse functional outcome (odds ratio [OR], 0.88; 95% CI, 0.78-0.99; P = .03). In individuals at CHR with a good functional outcome, positive associations were found between anger recognition and hippocampal volume (ze = 3.91; familywise error [FWE] P = .02) and between fear recognition and medial prefrontal cortex volume (z = 3.60; FWE P = .02), compared with participants with a poor outcome. The onset of psychosis was not associated with baseline emotion recognition performance (neutral OR, 0.93; 95% CI, 0.79-1.09; P = .37; happy OR, 1.03; 95% CI, 0.84-1.25; P = .81; fear OR, 0.98; 95% CI, 0.85-1.13; P = .77; anger OR, 1.00; 95% CI, 0.89-1.12; P = .96). No difference was observed in the association between performance and regional gray matter volumes in individuals at CHR who developed or did not develop psychosis (FWE P < .05). In this study, poor functional outcome in individuals at CHR was found to be associated with baseline abnormalities in recognizing negative emotion. This finding has potential implications for the stratification of individuals at CHR and suggests that interventions that target socioemotional processing may improve functional outcomes.

Outcomes of three-Tesla magnetic resonance imaging for the identification of pituitary adenoma in patients with Cushing's disease.

Pituitary adenoma has been reported to be detectable in only 36-63% of Cushing's disease (CD) patients by magnetic resonance imaging (MRI). In this study, we investigate the outcomes and problems associated with tumor identification using 3-Tesla (3-T) MRI, which provides clearer images than ≤1.5-T MRI, in 115 patients who were initially diagnosed with CD. Before surgery, 31 macroadenomas (27%) and 54 microadenomas (47%) were identified by 3-T MRI, but pituitary adenoma was invisible on MRI in the remaining 30 cases (26%). The smallest tumor diameter amenable to a definitive diagnosis was 2 mm, and spoiled gradient-echo was the best sequence for diagnosing microadenomas. In 14 of 30 cases of MRI-invisible CD, the pituitary adenoma was identified during surgery. Nine of these 14 tumors that developed from outside the pituitary gland were retrospectively identified on MRI by comparison with surgical findings. The remaining 16 cases of MRI-invisible CD in which the pituitary adenoma was not identified during surgery involved partial hypophysectomy. Seven cases were hormonally remitted, but another nine cases experienced persistent disease after surgery. The sensitivity and specificity of the pituitary adenoma diagnosis in CD patients after the introduction of 3-T MRI were 80% and 100%, respectively. However, the sensitivity decreased to 72% when macroadenomas were excluded. Some adenomas associated with CD are still undetectable on 3-T MRI due to tumor size, location and intensity. However, sensitivity can be improved by monitoring tumors that develop outside the pituitary gland.

Three-Tesla magnetic resonance imaging of the vestibular endolymphatic space: A systematic qualitative description in healthy ears

Background and PurposeA detailed knowledge of the normal Magnetic Resonance (MR) anatomy of the vestibular endolymphatic space (ES) could be useful to understand the linkage between endolymphatic hydrops (EH) and Ménière’s disease (MD). Our aim was to describe the MR anatomy of the vestibular ES as depicted by MR imaging in healthy ears. MethodsThis report describes a single-center retrospective study. Three readers analyzed the healthy ears of 22 consecutive patients who had undergone MRI for unilateral sudden hearing loss. The readers described the vestibular ES based on a delayed post-contrast 3D-FLAIR sequence according to six well-defined planes, three oblique sagittal (lateral, intermediate and medial) planes and three axial (superior, intermediate and inferior) planes. ResultsOn sagittal lateral and intermediate planes, we identified the SSC ampulla combined with the utricle in 22/22 ears. On the sagittal medial plane, the saccule was detectable in 15/22 (68%) ears, having a club shape with the long axis oriented cranio-caudally; in 7/22 (32%) ears, the saccule presented an oval/round shape that appeared more conspicuously on the axial intermediate plane. The ES occupied the half superior portion of the vestibule in 22/22 ears, never contacting the round and oval windows. On the axial plane, in 17/22 cases, the ES showed a Y-shaped arrangement, while in 5/22 ears (23%), the ES presented a more globular shape. ConclusionMR imaging represents a valid tool to explore the in vivo anatomy of the vestibular ES and to highlight its variability in normal ears.

Kinetic Asymmetry during Running at Preferred and Nonpreferred Speeds.

The aim of this study was to investigate the effect of altering preferred running speed by ±20% on kinetic asymmetry. Three-dimensional motion analysis and force data were acquired from 15 healthy males (age, 27 ± 4.6 yr; height, 1.81 ± 0.09 m; mass, 80.4 ± 12.4 kg) during their preferred running speed and at ±20% of this speed. Three-tesla magnetic resonance images were used to measure Achilles tendon cross-sectional area and moment arm, for use in calculation of tendon stress. Kinetic and tendon stress asymmetry were subsequently calculated in each condition using the symmetry index. Across all joints and conditions, the average asymmetry of peak moments was between ±6%, but higher individual values were observed. There was no effect of speed on the magnitude of asymmetry. Ground contact times, vertical ground reaction forces, and support and ankle moments (maximum absolute asymmetry, 9%) were more symmetrical than hip and knee moments (up to 18%). Individual joint contribution to support moment and positive work were similar in both limbs, and ankle and hip compensatory interactions were observed with alterations in running speed. Achilles tendon stress increased with increased running speed, with higher stress in the preferred limb; asymmetry in tendon stress was not related to asymmetry in vertical ground reaction forces. Results show small effects of altering running speed on kinetic asymmetry, but responses are individual specific with interactions occurring between joints to maintain overall movement symmetry. Further research is needed to understand the mechanical and neuromuscular mechanisms underpinning these compensations.

Variability in the Clock Face View Description of Femoral Tunnel Placement in ACL Reconstruction Using MRI-Based Bony Models

Though controversial, the "clock face view" of the intercondylar notch remains a way some surgeons communicate regarding placement of the femoral tunnel in anterior cruciate ligament reconstruction. The purpose of this study was to quantify the differences in angle measurement between several previous descriptions of the clock face view by using a new reference standard. Three-Tesla magnetic resonance imaging (MRI) was used to scan 10 human knees to create three-dimensional MRI-based bony models which were used for measurements. A standardized clock face view was developed with the knee flexed to 90° using the junction of the cartilage and cortex of the medial and lateral surfaces of medial and lateral femoral condyles as the 3 o'clock and 9 o'clock, respectively, with the 12 o'clock established as the midpoint of the roof of the intercondylar notch. With the knee viewed at 90° of flexion, an "idealized" femoral tunnel position was plotted on the medial wall of the lateral femoral condyle at 30° (corresponding to the 10 o'clock or 2 o'clock position). The clock faces as described by Edwards et al, Heming et al, and Mochizuki et al were each then overlaid on this same model and the difference in measurement calculated. The average angles measured when the previously described clock faces were projected onto the idealized clock face view comparing a mark made at 30° were 47.7°, 7.2°, and 49.8° for the methods described by Edwards et al, Heming et al, and Mochizuki et al, respectively (all p < 0.001). Significant variation exists between angle measurements in simulated femoral tunnel placement based on the varying descriptions of the intercondylar clock face.

Collagenase-Induced Rat Intra-Striatal Hemorrhage Mimicking Severe Human Intra-Striatal Hemorrhage.

Basal ganglia hemorrhage accounts for approximately 50% of all hemorrhagic strokes. A good rat model that produces severe intrastriatal hemorrhage (ISH) mimicking human severe ISH is lacking. The present study compared the intra-striatal injection of 0.2 U with that of 0.6 U of collagenase in inducing severe ISH in rats. Three-Tesla (3T) magnetic resonance imaging (MRI) was used to evaluate brain injuries in terms of hematoma size (volume), midline shift (MLS), and brain edema. This evaluation was further substantiated by determination of behavior and neurologic functions and mortality over 56 h. The 0.2 U collagenase caused hematoma volume increases for 10.3 to 30.1 mm³, while the 0.6 U caused 36.4 to 114.8 mm³, at post-ISH 1 h to 56 h. The 0.6 U collagenase significantly increased MLS to 1.5-3.0 times greater than the 0.2 U did at all post-intracerebral hemorrhage (ICH) time points. The MLS increased dependently with hematoma expansion with high correlation coefficients, yet no mortality occurred. These two dosages, nevertheless, caused the same pattern and severity in relative apparent diffusion coefficient (rADC) changes for three regions of interest (ROIs). Both ISH models induced consistent behavior deficits. The larger dosage produced severe brain injuries as well as neurological deficits, more closely mimicking severe human ISH. Hematoma volume and MLS can be the most useful parameters for evaluating the ISH severity in the present experimental model. The larger dosage, therefore, would be useful for investigating the pathophysiology of the severer ISH in the striatum. This may be applied for evaluating potential therapeutic strategies and outcomes in the future.

Five-Year Outcomes After Treatment for Acute Instability of the Tibiofibular Syndesmosis Using a Suture-Button Fixation System.

Background:Suture-button repair is a widely accepted surgical treatment for acute and isolated ankle syndesmosis injuries. To our knowledge, midterm results have not previously been reported.Purpose:To evaluate the clinical, qualitative, and quantitative radiological midterm outcomes of suture-button repair after acute isolated ankle syndesmosis injuries.Study Design:Retrospective case series; Level of evidence, 4.Methods:Clinical outcomes were measured using the Foot and Ankle Disability Index (FADI) and the American Orthopaedic Foot and Ankle Society (AOFAS) score. Three-tesla magnetic resonance imaging (MRI) was performed bilaterally at the ankle. Besides morphological sequences for evaluation of the syndesmosis and degenerative changes of the ankle using the Ankle Osteoarthritis Scoring System (AOSS), the MR protocol included a coronal 2-dimensional multislice multiecho sequence for quantitative cartilage T2-weighted mapping. Spearman correlations and paired t tests were used for statistical analysis.Results:This retrospective study included 19 consecutive patients (mean age, 29.7 ± 11.5 years) with acute isolated syndesmosis injuries treated with a suture-button system between January 2006 and June 2014, with a mean follow-up of 5.1 ± 2.6 years. Postoperatively, the median FADI score was 136 (range, 78-136), and the median AOFAS score was 100 (range, 87-100). Seventeen (89.5%) patients reported to have reached their preinjury level of sports activities. MRIs of 16 patients were obtained and all showed intact anterior and posterior syndesmotic ligaments; however, in most patients, the previously injured syndesmotic ligament was thickened compared with the uninjured ankle. Average width of the anterior (P = .81) and posterior (P = .60) syndesmosis was not significantly different between the ipsilateral (3.2 ± 1.2 and 4.4 ± 0.9 mm) and contralateral ankles (3.0 ± 0.6 and 4.2 ± 0.7 mm). The median AOSS score was 1.5 (range, 0-11) for the ipsilateral ankle and 0 (range, 0-6) for the contralateral ankle. T2 values of articular cartilage did not significantly differ between the involved and the uninjured ankle (P = .68). Five patients needed hardware removal due to persistent skin irritation, and 1 patient suffered from reinstability of the ankle resulting in revision surgery 2 years after the index surgery.Conclusion:Suture-button fixation is an excellent treatment for acute and isolated syndesmosis injuries, resulting in stable ankles without early or advanced osteoarthritic changes at midterm follow-up.

Polymer gel dosimetry for measuring the dose near thin high-Z materials irradiated with high energy photon beams.

To investigate the feasibility of three-dimensional (3D) dose measurements near thin high-Z materials placed in a water-like medium by using a polymer gel dosimeter (PGD) when the medium was irradiated with high energy photon beams. PGD is potentially a useful tool for this application because it can record the dose around a small object made of a high-Z material in a continuous 3D medium. In this study, the authors manufactured a methacrylic acid-based normoxic PGD, nMAG. Two 0.5 mm thick lead foils (1 × 1 cm) were placed in foil supports with 0.7 cm separation in a 1000 ml polystyrene container filled with nMAG. The authors used two foil configurations, i.e., orthogonal and parallel. In the orthogonal configuration, two foils were placed in the direction orthogonal to the beam axis. The parallel configuration had two foils arranged in parallel to the beam axis. The phantom was irradiated with an 18 MV photon beam of 5 × 5 cm field size. It was imaged with a three-Tesla (3 T) magnetic resonance imaging (MRI) scanned using the Car-Purcell-Meiboom-Gill pulse sequence. The spin-spin relaxation time (R2) to-dose calibration data were obtained by using small vials filled with nMAG and exposing to known doses. The DOSXYZnrc Monte Carlo (MC) code was used to get the expected dose distributions. More than 35 × 106 of histories were simulated so that the average error was less than 1%. An in-house matlab-based software was used to obtain the dose distributions from the measured R2 data as well as to compare the measurements and the MC predictions. The dose change due to the presence of the foils was studied by comparing the dose distributions with and without foils (or the reference). For the orthogonal configuration, the measured dose along the beam axis showed an increase in the upstream side of the first foil, between the foils, and on the downstream side of the second foil. The range of increased dose area was 1.1 cm in the upstream of the first foil. However, in the downstream of the second foil, it was 0.2 cm, beyond which the dose fell below the reference dose by 10%. The dose profile between the foils showed a well-like shape with the minimum dose still larger than the reference dose by 1.8%. The minimum dose point was closer to the first foil than to the second foil. For the parallel configuration, the dose between foils was the largest at the center. The increased dose area opposite to the gap between foils extended outward to 1 cm. The spatial dose distributions of PGD and MC showed the same geometrical patterns except for the points inside the foils for both orthogonal and parallel foil arrangements. The authors demonstrated that the nMAG PGD with MRI could be used to measure the 3D dosimetric structures at the mm-scale in the vicinity of the foil. The current study provided more accurate 3D spatial dose distribution than the previous studies. Furthermore, the measurements were validated by the MC simulation.

Prostate Cancer Magnetic Resonance Spectroscopy Imaging at 1.5 and 3.0 T: A Meta-Analysis.

We sought to assess the value of 1.5-T and 3-T magnetic resonance spectroscopy imaging in the diagnosis of prostate cancer by meta-analysis. Prospective studies were selected from MEDLINE, PubMed, Science Direct, OVID, and Springer between January 2004 and June 2014. Studies were reviewed based on Quality Assessment of Diagnostic Accuracy Studies criteria. Any publication bias was assessed using Deek funnel plot asymmetry test. Pooled sensitivities, specificities, positive likelihood ratios, negative likelihood ratios, and 95% confidence intervals were calculated. Summary receiver-operating characteristic curves were used to assess the results. A total of 17 articles were included in this study. The area under the curve values of 1.5-T magnetic resonance spectroscopy imaging with the use of an endorectal coil, 1.5-T magnetic resonance spectroscopy imaging without the use of an endorectal coil, and 3.0-T magnetic resonance spectroscopy imaging without the use of an endorectal coil were 0.90 ± 0.03, 0.75 ± 0.03, and 0.93 ± 0.02, respectively. Three-tesla magnetic resonance spectroscopy imaging without the use of an endorectal coil and 1.5-T magnetic resonance spectroscopy imaging with the use of an endorectal coil both had similar applied values compared to the lower applied value of 1.5-T magnetic resonance spectroscopy imaging without the use of an endorectal coil.

Technical Note: Compact three-tesla magnetic resonance imager with high-performance gradients passes ACR image quality and acoustic noise tests.

A compact, three-tesla magnetic resonance imaging (MRI) system has been developed. It features a 37 cm patient aperture, allowing the use of commercial receiver coils. Its design allows simultaneously for gradient amplitudes of 85 millitesla per meter (mT/m) sustained and 700 tesla per meter per second (T/m/s) slew rates. The size of the gradient system allows for these simultaneous performance targets to be achieved with little or no peripheral nerve stimulation, but also raises a concern about the geometric distortion as much of the imaging will be done near the system's maximum 26 cm field-of-view. Additionally, the fast switching capability raises acoustic noise concerns. This work evaluates the system for both the American College of Radiology's (ACR) MRI image quality protocol and the Food and Drug Administration's (FDA) nonsignificant risk (NSR) acoustic noise limits for MR. Passing these two tests is critical for clinical acceptance. In this work, the gradient system was operated at the maximum amplitude and slew rate of 80 mT/m and 500 T/m/s, respectively. The geometric distortion correction was accomplished by iteratively determining up to the tenth order spherical harmonic coefficients using a fiducial phantom and position-tracking software, with seventh order correction utilized in the ACR test. Acoustic noise was measured with several standard clinical pulse sequences. The system passes all the ACR image quality tests. The acoustic noise as measured when the gradient coil was inserted into a whole-body MRI system conforms to the FDA NSR limits. The compact system simultaneously allows for high gradient amplitude and high slew rate. Geometric distortion concerns have been mitigated by extending the spherical harmonic correction to higher orders. Acoustic noise is within the FDA limits.

Correlation of High PIRADS Score on Three-Tesla Magnetic Resonance with In-Gantry Magnetic Resonance Guided Biopsy in Patients with Clinical Risk of Prostate Cancer

Introduction and Objective: Prostate cancer detection is a difficult process despite different modalities that are available. The current standard of practice is based on stratifying risk using Prostate Specific Antigen (PSA), digital rectal examination (DRE) and performing a transrectal ultrasound (TRUS) or transperineal (TP) guided biopsy. Recent advances in three-tesla multiparametric magnetic resonance imaging (MP-MRI) technology and the availability of in-gantry MRI guided biopsies (MRGB) have added another diagnostic tool in management of prostate cancer. We review MRGB performed on high Prostate Imaging Reporting and Data System (PIRADS) score lesions in a single centre retrospective study. Materials and Methods: There were 77 patients (mean age 63) with high PIRADS score (4 and 5) that underwent in-gantry MRGB. All the biopsies were performed utilizing dynacad prostate biopsy system on a three-tesla MRI scanner by an urologist with assistance of an experienced radiologist. Two to three samples were obtained from each lesion using an MRI compatible 18-gauge biopsy needle. Three experienced pathologists evaluated the samples and provided the results and Gleason score in each positive sample. Results: Out of the total 77 high PIRADS patients, 54 were PIRADS score 4 (70%) and 23 PIRADS score 5 (30%). There were 22 positive biopsies for adenocarcinoma of prostate with a Gleason score of 3 + 3 = 6 or higher. Out of the 54 PIRADS score 4 lesions, 13 were positive (24%) and out of 23 PIRADS 5 lesions, 9 were positive (39%). The remaining 55 biopsies were negative for prostate cancer. Conclusion: We present our series of MRGB in patients with a high PIRADS score for prostate cancer. While this diagnostic paradigm was in its infancy stages, MRGB was positive in 24% of PIRADS 4 and 39% of PIRADS 5 lesions in this series.