Echo Proton Research Articles

Dorsal wrist ganglion: clinical and imaging correlation in symptomatic population based on high-field MRI

ObjectivesTo determine prevalence in the symptomatic population of dorsal mucoid cysts centered on dorsal capsuloscapholunate septum (DCSS) using high-field magnetic resonance imaging (MRI) for anatomoclinical and epidemiological correlations.Materials and methodsThis single-center retrospective study analyzed all 3-Tesla MRIs consecutively performed for painful wrists in 295 patients. Two blinded readers performed measurements. The protocol included T1 spin echo and 3D proton density sequences with fat saturation. Inter-observer reliability was assessed using kappa and intra-class correlation coefficients for cyst detection and volumetry, respectively. Disagreements concerning cyst detection were resolved by a consensus reading. Cyst size, relationship to extrinsic and scapholunate ligaments (SL), continuity of SL, minimum distance to the posterior interosseous nerve (PIN), cyst communication with joint, and anatomical classifications of cysts were analyzed. Correlation tests were performed to assess associations.ResultsTwo-hundred ninety-five patients (mean age 39.6 +/− 15.6 (standard deviation), 161 males) were evaluated for detection of dorsal wrist cysts identified in 150/295. In this subgroup, the mean age was 38.7 years (15–75), the sex ratio of 0.6 (59% women), and the median volume cyst of 8.7 mm3 (0.52–2555). Cyst detection, volume, and major axis measurements showed very high agreement between observers, respectively, 0.89, 0.96, and 0.91. 42 patients had dorsal SL pain. A weak negative correlation was found between distance to PIN and dorsal SL pain (r = −0.2415; p < 0.05) and a weak positive correlation between Guérini’s classification and dorsal SL pain (r = 0.2466; p < 0.05).ConclusionHigh-field MRI is the modality of choice for the detection, anatomical, and volumetric assessment of dorsal cysts. Preoperative assessment will be aided by the proposed revised anatomical classification.Clinical relevance statementHigh-field MRI is the modality of choice for the anatomical study of dorsal ganglion cysts. It allows the radiologist to accurately describe the anatomical relationships, size, and visibility of the pedicle, essential information for the surgeon’s preoperative assessment.Key PointsDorsal mucoid wrist ganglion is a condition for which prevalence remains to be determined.High-field MRI is a reproducible imaging modality for the detection and assessment of dorsal wrist cysts.High-field MRI has a key role in the preoperative management of dorsal mucoid cysts.

A Comparative Study on the Diagnostic Value of Conventional Spin Echo Proton Density and Fast Spin Echo Proton Density Sequences of Magnetic Resonance Imaging in Diagnosis of Meniscal Tear

Background &amp; Objectives: Knee is the largest synovial joint in the body. Although FSE PD (fastspin echo proton density) imaging technique for the diagnosis of meniscal tear has replaced CSE PD(conventional spin echo proton density) technique in many MRI centers, several studies have questionedthe effectiveness of FSE PD technique in diagnosis of meniscal tear. In this study, the diagnostic valuesof CSE PD and FSE PD techniques in evaluation of meniscus tear are compared.Materials: In this study, using CSE PD and FSE PD techniques, MRI was performed on 67 knees ofpatients with suspected meniscal tear referring to the MRI Center of Imam Reza Hospital (Kermanshah,Iran). Diagnostic arthroscopy was also performed for all patients. The data were entered SPSS version20, and finally the results of MRI reports of the two techniques were compared in evaluation of meniscaltear taking into account the arthroscopic findings as the gold standard.Results: According to the results of this study, no significant difference was found in specificity andpositive predictive value of the two techniques. However, the sensitivity and negative predictive valueswere significantly different, in such a way that the related values were 97% and 97% in the CSE PDtechnique and 69% and 73% in the FSE PD technique, respectively.Conclusion: Due to low sensitivity and high false negative results, MRI using FSE PD technique is notrecommended as an alternative for CSE PD technique in evaluation of meniscal tear.

T2 Relaxometry Evidence of Microstructural Changes in Diffusely Abnormal White Matter in Relapsing–Remitting Multiple Sclerosis and Clinically Isolated Syndrome: Impact on Visuomotor Performance

BackgroundAlthough diffusely abnormal white matter (DAWM) is commonly seen in multiple sclerosis (MS), it is rarely considered in clinical/imaging studies.PurposeTo evaluate quantitative markers of microstructural changes in DAWM of patients with clinically isolated syndrome (CIS) and relapsing–remitting MS (RR‐MS) in relation to MS lesions and degree of neurocognitive impairment, by using a multi‐echo spin echo (MESE) Proton Density PD‐to‐T2 sequence.Study TypeProspective, cross‐sectional.PopulationThirty‐seven RR‐MS patients, 33 CIS patients, and 52 healthy controls.Field Strength/Sequence1.5 T/T1‐, T2‐weighted, fluid‐attenuated inversion recovery, and MESE sequences.AssessmentLong T2, short T2, and myelin water fraction (MWF) values were estimated as indices of intra/extracellular water content and myelin content, respectively, in DAWM, posterior periventricular normal appearing white matter (NAWM), and focal MS lesions, classified according to their signal intensity on T1 sequences. Patients were, also, administered a battery of neuropsychological tests.Statistical TestsComparisons of T2 and MWF values in DAWM, NAWM, and MS lesions were examined, using two‐way mixed analyses of variance. Associations of Grooved Pegboard performance with T2 and MWF values in DAWM and NAWM were assessed using Pearson correlation coefficients.ResultsT2 and MWF values of DAWM were intermediate between the respective values of NAWM and T1 hypointense focal lesions, while there was no difference between the respective values of DAWM and T1‐isointense lesions. T2 values in DAWM were strongly associated with visuomotor performance in CIS patients.Data ConclusionIntra/extracellular water and myelin water content of DAWM are similar to those of T1‐isointense lesions and predict visuomotor performance in CIS patients.Level of Evidence2Technical EfficacyStage 2

MRI presentation and pathogenesis of tennis legs

Objective To evaluate the imaging features of MRI of tennis legs and to explore the pathogenesis of tennis legs. Methods A retrospective analysis was made on the MRI images of 38 patients with tennis legs which met the criteria and were clinically diagnosed in our hospital from May 2014 to June 2018. All patients underwent non-enhanced MRI. Coronal T1WI、T2WI fast spin echo (TSE) and transverse proton density weighted imaging (PDWI) were performed. The signs of fluid collection between gastrocnemius muscle (GM) and soleus muscle (SM),muscle and tendon injuries, superficial vein dilatation of calf were observed and recorded. Results Coronal T1WI, T2WI TSE and transverse PDWI sequences showed 30 (75.0%) places fluid collection (hematoma or effusion) between medial head of the gastrocnemius muscle (MCM) and SM,11 (27.5%) places fluid collection (hematoma or effusion) between lateral head of gastrocnemius muscle (LGM) and SM,7 (17.5%) places fluid collection (hematoma or effusion) in MGM and 2 (5.0%) placesin SM. There were 17 (42.5%) places that hematoma or effusion spread around the fascia of the lower leg. The diameter and thickness of hematoma or effusion are about 1.7-22.3 cm and 0.2-3.5 cm,respectively. Rupture of the GM was seen in 37 (92.5%) places,including 37 places rupture of the MGM at the myotendinous junction, 15 places rupture of the LGM at the myotendinous junction, 24 places tendonrupture of MGM,3 places tendon rupture of MGM and LGM,and 2 places tendon rupture of LGM. The maximum diameter of tendon rupture was 1.2-27.0 mm. The muscle rupture of MGM was seen in one place,and muscle rupture of MGM and LGM was seen in one place at the same time. Rupture of the SM was seen in15 (37.5%) places,including 15 places rupture of the SM at the myotendinous junction, 2 places muscle rupture of SM, 6 places tendonrupture of SM. The maximum diameter of tendon rupture was 2.5-14.9 mm. Rupture of plantaris tendon (PT) was seen in 4 (10.0%) places. Superficial vein dilatation was seen in 3 (7.5%) places. Conclusion This study shows that the rupture of the MGM at the myotendinous junction and the tendon is the main responsibility of tennis leg. Key words: Tennis legs; Gastrocnemius muscle; Plantaris tendon; Soleus muscle

Validation of an MRI Protocol for Routine Quantitative Assessment of Tunnel Position in Anterior Cruciate Ligament Reconstruction

Background: No standardized methodology and objective criteria currently exist to accurately and objectively assess tunnel placement and consequent graft orientation in anterior cruciate ligament (ACL) reconstruction (ACLR) through a single imaging modality. Advances in magnetic resonance imaging (MRI) technology have enabled the use of volumetric high spatial and contrast resolution proton density–weighted sequencing, which allows precise delineation of graft orientation, tunnel position, and quantitative assessment of tunnel position relationship to adjacent reproducible anatomic landmarks. Purpose: To establish an MRI protocol that would provide an accurate alternative to 3-dimensional computed tomography (3D-CT) for standardized assessment of bone tunnel placement in ACLR, as a component of assessing ACLR outcomes and to assist in presurgical planning for revision ACLR. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Twenty-four participants diagnosed with a failed ACLR underwent MRI and 3D-CT per the imaging protocols of the Sydney Orthopaedic Research Institute, in which the acquired data were converted to 3D models. The bone tunnels of the previous ACLR were then intraoperatively digitized at the tunnel aperture and along the length of the tunnel (barrel) and used as the reference standard to evaluate the accuracy of high-resolution MRI and 3D-CT. Differences in geometry between the image-based model and the reference point cloud were calculated through point-to-point comparison. Results: At the tunnel apertures, no significant differences were detected between the MRI and 3D-CT models versus the reference models for the femur (P = .9472) and tibia (P = .5779). Mean ± SD tunnel barrel deviations between MRI and 3D-CT were 0.48 ± 0.28 mm (femur) and 0.46 ± 0.27 mm (tibia). No significant differences were detected between the MRI and 3D-CT models versus the reference models for the femoral (P = .5730) and tibial (P = .3002) tunnel barrels. Conclusion: This study demonstrated that, in addition to being the optimum modality for assessment of soft tissue injury of the knee, a high-resolution 3D turbo spin echo proton density sequence can provide an accurate assessment of tunnel placement, without the use of ionizing radiation. Therefore, this protocol provides the foundation for an objective standardized platform to quantitatively evaluate the location of ACL bone tunnels and graft orientation for routine postoperative assessment, presurgical planning, and evaluation of clinical outcomes.

176. Hyperglutamatergia and Bioenergetic Metabolism in Schizophrenia: Next Generation of Studies

Abstract Overall Abstract: Pharmacologic, genetic, postmortem, and imaging studies have firmly established schizophrenia as a disorder of excitatory synapses. Consistently, the first generation of H-MRS studies with single voxels and lower field strengths have mostly confirmed subtle increases in brain glutamate. However, the translational effort linked to this body of research has been disappointing with no efficacious glutamatergic drugs identified so far. A renewed effort to understand the spatial distribution, timing, clinical correlates, and underlying mechanisms of glutamatergic dysfunction is warranted. Hence, we present a new generation of studies with various methodological advances: broad spatial imaging of glutamate (proton echo planar spectroscopic imaging at 3T), improved spectral resolution of glutamate metabolites and lactate (H-MRS at 7T), dynamic assessment of phosphoenergetics and its relationship with glutamate (31P MRS at 4T) as well as postmortem and animal model investigations of the molecular bioenergetics of the glial/synaptic units. These studies provide converging evidence that early in schizophrenia, there is a cortical hyperglutamatergic process, linked to a fundamental shift toward anaerobic metabolism, alteration in the lactate shuttle with accumulation of lactate, and decreased availability of ATP, which accounts for part of the cognitive and functional deficits that persist, despite dopamine D2 blockade provided by standard treatment. The implications from these data, for the development of novel pharmacological strategies, will be discussed.

Brain metabolite levels and language abilities in preschool children

IntroductionLanguage acquisition occurs rapidly during early childhood and lays the foundation for future reading success. However, little is known about the brain–language relationships in young children. The goal of this study was to investigate relationships between brain metabolites and prereading language abilities in healthy preschool‐aged children.MethodsParticipants were 67 healthy children aged 3.0–5.4 years scanned on a 3T GE MR750w MRI scanner using short echo proton spectroscopy with a voxel placed in the anterior cingulate gyrus (n = 56) and/or near the left angular gyrus (n = 45). Children completed the NEPSY‐II Phonological Processing and Speeded Naming subtests at the same time as their MRI scan. We calculated glutamate, glutamine, creatine/phosphocreatine, choline, inositol, and NAA concentrations, and correlated these with language skills.ResultsIn the anterior cingulate, Phonological Processing Scaled Scores were significantly correlated with glutamate, creatine, and inositol concentrations. In the left angular gyrus, Speeded Naming Combined Scaled Scores showed trend correlations with choline and glutamine concentrations.ConclusionsFor the first time, we demonstrate relationships between brain metabolites and prereading language abilities in young children. Our results show relationships between language and inositol and glutamate that may reflect glial differences underlying language function, and a relationship of language with creatine. The trend between Speeded Naming and choline is consistent with previous research in older children and adults; however, larger sample sizes are needed to confirm whether this relationship is indeed significant in young children. These findings help understand the brain basis of language, and may ultimately lead to earlier and more effective interventions for reading disabilities.

Biomarkers of response to transcranial magnetic stimulation in youth with treatment resistant major depression

BackgroundMajor depressive disorder (MDD) affects approximately 15% of youth, half of who do not respond to standard treatment. One promising intervention is repetitive transcranial magnetic stimulation (rTMS). However, response is limited, highlighting the need to focus on biomarkers to predict treatment response.ObjectivesTo explore baseline biomarkers of response associated with rTMS treatment in adolescent MDD.AimsTo determine the association between dorsolateral prefrontal cortex (DLPFC) glutamate levels, cortical thickness, and cerebral blood flow (CBF) with MDD symptomatology decrease after rTMS intervention.MethodsTwenty-four MDD youth underwent 3 weeks of rTMS, baseline and post-intervention magnetic resonance imaging scans, and short echo proton magnetic resonance spectroscopy. Response was determined by a 50% reduction of depression scores.ResultsDepressive symptoms decreased with rTMS (t = 8.304, P = 0.00). Glutamate levels differed significantly between responders and non-responders (t = 2.24, P = 0.0039), where higher glutamate changes were associated with a better response (r = 0.416, P = 0.038). Responders also exhibited thinner DLPFC (r = –0.797, P = 0.000) and lower CBF levels.ConclusionsThe development of biomarkers for rTMS represents a novel and encouraging technique for a personalized and effective treatment while reducing ineffective treatment costs and personal burden in adolescent MDD.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Combining parallel detection of proton echo planar spectroscopic imaging (PEPSI) measurements with a data-consistency constraint improves SNR.

One major challenge of MRSI is the poor signal-to-noise ratio (SNR), which can be improved by using a surface coil array. Here we propose to exploit the spatial sensitivity of different channels of a coil array to enforce the k-space data consistency (DC) in order to suppress noise and consequently to improve MRSI SNR. MRSI data were collected using a proton echo planar spectroscopic imaging (PEPSI) sequence at 3 T using a 32-channel coil array and were averaged with one, two and eight measurements (avg-1, avg-2 and avg-8). The DC constraint was applied using a regularization parameter λ of 1, 2, 3, 5 or 10. Metabolite concentrations were quantified using LCModel. Our results show that the suppression of noise by applying the DC constraint to PEPSI reconstruction yields up to 32% and 27% SNR gain for avg-1 and avg-2 data with λ = 5, respectively. According to the reported Cramer-Rao lower bounds, the improvement in metabolic fitting was significant (p < 0.01) when the DC constraint was applied with λ ≥ 2. Using the DC constraint with λ = 3 or 5 can minimize both root-mean-square errors and spatial variation for all subjects using the avg-8 data set as reference values. Our results suggest that MRSI reconstructed with a DC constraint can save around 70% of scanning time to obtain images and spectra with similar SNRs using λ = 5.

Statistical mapping of metabolites in the medial wall of the brain: a proton echo planar spectroscopic imaging study.

With magnetic resonance spectroscopic imaging (MRSI), it is possible to simultaneously map distributions of several brain metabolites with relatively good spatial resolution in a short time. Although other functional imaging modalities have taken advantage of population-based inferences using spatially extended statistics, this approach remains little utilized for MRSI. In this study, statistical nonparametric mapping (SnPM) was applied to two-dimensional MRSI data from the medial walls of the human brain to assess the effect of normal aging on metabolite concentrations. The effects of different preprocessing steps on these results were then explored. Short echo time MRSI of left and right medial walls was acquired in conjunction with absolute quantification of total choline, total creatine (tCr), glutamate and glutamine, myo-inositol, and N-acetyl-aspartate. Individual images were spatially warped to a common anatomical frame of reference. Age effects were assessed within SnPM as were the effects of voxel subsampling, variance smoothing, and spatial smoothing. The main findings were: (1) regions in the bilateral dorsal anterior cingulate and in the left posterior cingulate exhibited higher tCr concentrations with age; (2) voxel subsampling but not spatial smoothing enhanced the cluster-level statistical sensitivity; and (3) variance smoothing was of little benefit in this study. Our study shows that spatially extended statistics can yield information about regional-specific changes in metabolite concentrations obtained by short echo time MRSI. This opens up the possibility for systematic comparisons of metabolites in the medial wall of the brain.

Glutamate alterations associated with transcranial magnetic stimulation in youth depression: a case series.

We hypothesized an increase in dorsolateral prefrontal cortex (DLPFC) glutamate levels would occur after 3 weeks of repetitive transcranial magnetic stimulation (rTMS) treatment and a decrease in major depressive disorder (MDD) symptoms. We report 6 patients (4 females) 15 to 21 years of age with treatment-resistant MDD. Participants had a mean (SD) age of 18.7 (1.95) years and a mean (SD) IQ of 102.3 (3.39). Short echo proton magnetic resonance spectroscopy (¹H-MRS) was used to quantify glutamate levels in the left DLPFC (4.5 cc) before and after rTMS treatment. Repetitive transcranial magnetic stimulation was localized to the left DLPFC and applied for 15 consecutive weekdays (120% resting motor threshold; 40 pulses over 4 seconds [10 Hz]; intertrain interval, 26 seconds; 75 trains; 3000 pulses). Treatment response was defined as a greater than 50% reduction in Hamilton Depression Rating Scale scores. Short echo proton magnetic resonance spectroscopy data were analyzed with LCModel to determine glutamate concentration. After rTMS, treatment responders (n = 4) showed an increase (relative to baseline) in left DLPFC glutamate levels (11%), which corresponded to an improvement in depressive symptom severity (68% Hamilton Depression Rating Scale score reduction). Treatment nonresponders (n = 2) had elevated baseline glutamate levels compared to responders in that same region, which decreased with rTMS (-10%). Procedures were generally well tolerated with no adverse events. Repetitive transcranial magnetic stimulation is feasible and possibly efficacious in adolescents with MDD. In responders, rTMS may act by induced elevations in elevating DFPLC glutamate levels in the left DLPFC, thereby leading to symptom improvement.

Rapid and robust pulmonary proton ZTE imaging in the mouse.

Pulmonary MRI is challenging because of the low proton density and rapid transverse relaxation in the lung associated with microscopic magnetic field inhomogeneities caused by tissue-air interfaces. Therefore, low signal is obtained in gradient and spin echo proton images. Alternatively, non-proton MRI using hyperpolarized gases or radial techniques with ultrashort or zero TE have been proposed to image the lung. Also with the latter approach, the general challenge remains to provide full coverage of the lung at sufficient spatial resolution, signal-to-noise ratio (SNR) and image quality within a reasonable scan time. This task is further aggravated by physiological motion and is particularly demanding in small animals, such as mice. In this work, three-dimensional (3D) zero echo time (ZTE) imaging is employed for efficient pulmonary MRI. Four protocols with different averaging and respiratory triggering schemes are developed and compared with respect to image quality and SNR. To address the critical issue of background signal in ZTE images, a subtraction approach is proposed, providing images virtually free of disturbing signal from nearby hardware parts. The protocols are tested for pulmonary MRI in six mice at 4.7 T, consistently providing images of high quality with a 3D isotropic resolution of 313 µm and SNR values in the lung between 8.0 and 18.5 within scan times between 1 min 21 s and 4 min 44 s. A generally high robustness of the ZTE approach against motion is observed, whilst respiratory triggering further improves the SNR and visibility of image details. The developed techniques are expected to enable efficient preclinical animal studies in the lung and will also be of importance for human applications. Further improvements are expected from radiofrequency (RF) coils with increased SNR and reduced background signal.

Comparing proton density and turbo spin echoT2weighted static sequences with dynamic half-Fourier single-shot TSE pulse sequence at 3.0 T in diagnosis of temporomandibular joint disorders: a prospective study

The aim of this prospective study was to compare dynamic and static sequences in the evaluation of temporomandibular joint disorders using a 3.0 -T imaging unit. 194 patients were evaluated by static (double echo proton density weighted/turbo spin echo T2 weighted sequences) and dynamic (half-Fourier single-shot turbo spin echo sequences)imaging. Two radiologists evaluated in consensus the quality of images, the disc position and morphological alterations. The Kendall rank correlation coefficient (τ-b) was used to compare the qualitative rating between static and dynamic sequences. Cohen's kappa coefficient (k) was used to assess the agreement of disc position and morphological alterations between both sequences. The intraclass correlation coefficient was used to calculate the intraobserver variability. The significance was set at p ≤ 0.05. The correlation between both sequences in the qualitative evaluation was τ-b = 0.632. The agreement between both techniques in the evaluation of disc position was k = 0.856. The agreement between both techniques in assessing the morphological alterations was k = 0.487. In the static sequences, the intraclass correlation coefficient was 0.915 in the qualitative evaluation, 0.873 in the evaluation of disc position and 0.934 in the assessment of morphological alterations. In the dynamic sequences, the intraclass correlation coefficient was 0.785 in the qualitative evaluation, 0.935 in the evaluation of disc position and 0.826 in the assessment of morphological alterations. Static imaging remains the gold standard in the evaluation of the temporomandibular joint. Dynamic imaging is a valuable tool that can provide additional information about topographic changes in the disc-condyle relationship.

A comparative MRI study for white matter hyperintensities detection: 2D-FLAIR, FSE PD 2D, 3D-FLAIR and FLAIR MIP

The main objective of this study was to not only determine the most appropriate sequence for the analysis of white matter hyperintensities (WMH) on MRI but also to confirm the advantage of three-dimensional (3D) acquisition, as it has been suggested in previous studies, and to test the convenience of using maximum intensity projection (MIP) algorithms on 3D-fluid-attenuated inversion-recovery (FLAIR) images for a quicker evaluation of brain MR studies. The number of WMH was compared in 40 patients and a control group of 10 volunteers using 4 different imaging modalities: two dimensional (2D)-FLAIR, 2D fast spin echo proton density (FSE PD), 3D-FLAIR and FLAIR MIP. Four experienced radiologists took part in the imaging analysis. All studies were performed on a 1.5-T whole-body MR unit. A statistically significant difference between the number of lesions detected on 3D acquisitions (FLAIR CUBE® or FLAIR MIP sequences) compared with those on 2D-FLAIR or 2D FSE PD was demonstrated. There is no significant difference between 3D-FLAIR and FLAIR MIP, therefore both of them can be used with similar results. 3D-FLAIR sequences should replace conventional 2D-FLAIR and/or FSE PD sequences in the MR acquisition protocol when WMH are suspected. MIP reformat algorithms are less time consuming, therefore these can also be used to simplify the detection. 3D sequences are superior for WMH depiction. Moreover, MIP algorithms allow easier analyses with similar results.

EPA-1180 – Glutamate alterations associated with transcranial magnetic stimulation in youth depression: a case series

Objective We hypothesized an increase in dorsolateral prefrontal cortex (DLPFC) glutamate levels would occur after three weeks of repetitive transcranial magnetic stimulation (rTMS) treatment and a decrease in major depressive disorder (MDD) symptoms. Method We report six cases (four females) 15–21 years of age with treatment-resistant MDD. Participants had a mean age of 18.7 years (SD ±1.95) and a mean IQ of 102.3(±3.39). Short echo proton magnetic resonance spectroscopy (1H-MRS) was used to quantify glutamate levels in the left DLPFC (4.5 cc) before and after rTMS treatment. rTMS was localized to the left DLPFC and applied for 15 consecutive weekdays (120% RMT, 40 pulses over 4 seconds (10 Hz), inter-train interval 26 seconds, 75 trains, 3000 pulses). Treatment response was defined as a greater than 50% reduction in Hamilton Depression Rating Scale scores (Ham-D). 1H-MRS data was analyzed with LCModel to determine glutamate concentration. Results Following rTMS, treatment responders (N=4) showed an increase (relative to baseline) in left DLPFC glutamate levels (11%), which corresponded to an improvement in depressive symptom severity (68% Ham-D score reduction). Treatment non-responders (N=2) had elevated baseline glutamate levels compared to responders in that same region, which decreased with rTMS (−10%). Procedures were generally well tolerated with no adverse events. Conclusions rTMS is feasible and possibly efficacious in adolescents with MDD. In responders, rTMS may act by Induced elevations in elevating DFPLC glutamate levels in the left DLPFC, thereby leading to symptom improvement. Transcranial Magnetic Stimulation for Adolescent Depression (TMSAD).

EPA-0491 – Glutamate alterations associated with transcranial magnetic stimulation in youth depression: a case series ‘ptsd and the phantom of the opera’

Objective We hypothesized an increase in dorsolateral prefrontal cortex (DLPFC) glutamate levels would occur after three weeks of repetitve transcranial magnetic stimulation (rTMS) treatment and a decrease in major depressive disorder (MDD) symptoms. Method We report six cases (four females) 15–21 years of age with treatment-resistant MDD. Participants had a mean age of 18.7 years and a mean IQ of 102.3. Short echo proton magnetic resonance spectroscopy (H-MRS) was used to quantify glutamate levels in the left DLPFC (4.5cc) before and after rTMS treatment. rTMS was localized to the left DLPFC and applied for 15 consecutive weekdays. Treatment response was defined as a greater than 50% reduction in Hamilton Depression Rating Scale scores (Ham-D).1H-MRS data was analyzed with LCModel to determine glutamate concentration. Results Following rTMS, treatment responders (N=4) showed an increase (relative to baseline) in left DLPFC glutamate levels (11%), which corresponded to an improvement in depressive symptom severity (68% Ham-D score reduction). Treatment non-responders (N=2) had elevated baseline glutamate levels compared to responders in that same region, which decreased with rTMS (−10%). Procedures were generally well tolerated with no adverse events. Conclusions rTMS is feasible and possibly efficacious in adolescents with MDD. In responders, rTMS may act by Induced elevations in elevating DFPLC glutamate levels in the left DLPFC, thereby leading to symptom improvement. Transcranial Magnetic Stimulation for Adolescent Depression (TMSAD)

CANNABINOID USE IN PROGRESSIVE INFLAMMATORY BRAIN DISEASE (CUPID) MRI SUB–STUDY

IntroductionIn progressive Multiple Sclerosis (MS), there is no proven therapy for preventing accumulation of irreversible disability. The pathological substrate of irreversible disability in MS is neuroaxonal loss, and brain tissue...

Short- and long-term quantitation reproducibility of brain metabolites in the medial wall using proton echo planar spectroscopic imaging

Proton echo planar spectroscopic imaging (PEPSI) is a fast magnetic resonance spectroscopic imaging (MRSI) technique that allows mapping spatial metabolite distributions in the brain. Although the medial wall of the cortex is involved in a wide range of pathological conditions, previous MRSI studies have not focused on this region. To decide the magnitude of metabolic changes to be considered significant in this region, the reproducibility of the method needs to be established. The study aims were to establish the short- and long-term reproducibility of metabolites in the right medial wall and to compare regional differences using a constant short-echo time (TE30) and TE averaging (TEavg) optimized to yield glutamatergic information. 2D sagittal PEPSI was implemented at 3T using a 32 channel head coil. Acquisitions were repeated immediately and after approximately 2 weeks to assess the coefficients of variation (COV). COVs were obtained from eight regions-of-interest (ROIs) of varying size and location. TE30 resulted in better spectral quality and similar or lower quantitation uncertainty for all metabolites except glutamate (Glu). When Glu and glutamine (Gln) were quantified together (Glx) reduced quantitation uncertainty and increased reproducibility was observed for TE30. TEavg resulted in lowered quantitation uncertainty for Glu but in less reliable quantification of several other metabolites. TEavg did not result in a systematically improved short- or long-term reproducibility for Glu. The ROI volume was a major factor influencing reproducibility. For both short- and long-term repetitions, the Glu COVs obtained with TEavg were 5-8% for the large ROIs, 12-17% for the medium sized ROIs and 16-26% for the smaller cingulate ROIs. COVs obtained with TE30 for the less specific Glx were 3-5%, 8-10% and 10-15%. COVs for N-acetyl aspartate, creatine and choline using TE30 with long-term repetition were between 2-10%. Our results show that the cost of more specific glutamatergic information (Glu versus Glx) is the requirement of an increased effect size especially with increasing anatomical specificity. This comes in addition to the loss of sensitivity for other metabolites. Encouraging results were obtained with TE30 compared to other previously reported MRSI studies. The protocols implemented here are reliable and may be used to study disease progression and intervention mechanisms.

Quantitative mapping of total choline in healthy human breast using proton echo planar spectroscopic imaging (PEPSI) at 3 Tesla

To quantitatively measure tCho levels in healthy breasts using Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI). The two-dimensional mapping of tCho at 3 Tesla across an entire breast slice using PEPSI and a hybrid spectral quantification method based on LCModel fitting and integration of tCho using the fitted spectrum were developed. This method was validated in 19 healthy females and compared with single voxel spectroscopy (SVS) and with PRESS prelocalized conventional Magnetic Resonance Spectroscopic Imaging (MRSI) using identical voxel size (8 cc) and similar scan times (∼7 min). A tCho peak with a signal to noise ratio larger than 2 was detected in 10 subjects using both PEPSI and SVS. The average tCho concentration in these subjects was 0.45 ± 0.2 mmol/kg using PEPSI and 0.48 ± 0.3 mmol/kg using SVS. Comparable results were obtained in two subjects using conventional MRSI. High lipid content in the spectra of nine tCho negative subjects was associated with spectral line broadening of more than 26 Hz, which made tCho detection impossible. Conventional MRSI with PRESS prelocalization in glandular tissue in two of these subjects yielded tCho concentrations comparable to PEPSI. The detection sensitivity of PEPSI is comparable to SVS and conventional PRESS-MRSI. PEPSI can be potentially used in the evaluation of tCho in breast cancer. A tCho threshold concentration value of ∼0.7 mmol/kg might be used to differentiate between cancerous and healthy (or benign) breast tissues based on this work and previous studies.

Optimizing Hippocampal Segmentation in Infants Utilizing MRI Post-Acquisition Processing

This study aims to determine the most reliable method for infant hippocampal segmentation by comparing magnetic resonance (MR) imaging post-acquisition processing techniques: contrast to noise ratio (CNR) enhancement, or reformatting to standard orientation. MR scans were performed with a 1.5 T GE scanner to obtain dual echo T2 and proton density (PD) images at term equivalent (38-42 weeks' gestational age). 15 hippocampi were manually traced four times on ten infant images by 2 independent raters on the original T2 image, as well as images processed by: a) combining T2 and PD images (T2-PD) to enhance CNR; then b) reformatting T2-PD images perpendicular to the long axis of the left hippocampus. CNRs and intraclass correlation coefficients (ICC) were calculated. T2-PD images had 17% higher CNR (15.2) than T2 images (12.6). Original T2 volumes' ICC was 0.87 for rater 1 and 0.84 for rater 2, whereas T2-PD images' ICC was 0.95 for rater 1 and 0.87 for rater 2. Reliability of hippocampal segmentation on T2-PD images was not improved by reformatting images (rater 1 ICC = 0.88, rater 2 ICC = 0.66). Post-acquisition processing can improve CNR and hence reliability of hippocampal segmentation in neonate MR scans when tissue contrast is poor. These findings may be applied to enhance boundary definition in infant segmentation for various brain structures or in any volumetric study where image contrast is sub-optimal, enabling hippocampal structure-function relationships to be explored.