Siemens Skyra Research Articles

Neuropathological characteristics of abnormal white matter functional signaling in adolescents with major depression.

Major depression disorder (MDD) constitutes a significant mental health concern. Epidemiological surveys indicate that the lifetime prevalence of depression in adolescents is much higher than that in adults, with a corresponding increased risk of suicide. In studying brain dysfunction associated with MDD in adole-scents, research on brain white matter (WM) is sparse. Some researchers even mistakenly regard the signals generated by the WM as noise points. In fact, studies have shown that WM exhibits similar blood oxygen level-dependent signal fluctuations. The alterations in WM signals and their relationship with disease severity in adolescents with MDD remain unclear. To explore potential abnormalities in WM functional signals in adolescents with MDD. This study involved 48 adolescent patients with MDD and 31 healthy controls (HC). All participants were assessed using the Patient Health Questionnaire-9 Scale and the mini international neuropsychiatric interview (MINI) suicide inventory. In addition, a Siemens Skyra 3.0T magnetic resonance scanner was used to obtain the subjects' image data. The DPABI software was utilized to calculate the WM signal of the fractional amplitude of low frequency fluctuations (fALFF) and regional homogeneity, followed by a two-sample t-test between the MDD and HC groups. Independent component analysis (ICA) was also used to evaluate the WM functional signal. Pearson's correlation was performed to assess the relationship between statistical test results and clinical scales. Compared to HC, individuals with MDD demonstrated a decrease in the fALFF of WM in the corpus callosum body, left posterior limb of the internal capsule, right superior corona radiata, and bilateral posterior corona radiata [P < 0.001, family-wise error (FWE) voxel correction]. The regional homogeneity of WM increased in the right posterior limb of internal capsule and left superior corona radiata, and decreased in the left superior longitudinal fasciculus (P < 0.001, FWE voxel correction). The ICA results of WM overlapped with those of regional homo-geneity. The fALFF of WM signal in the left posterior limb of the internal capsule was negatively correlated with the MINI suicide scale (P = 0.026, r = -0.32), and the right posterior corona radiata was also negatively correlated with the MINI suicide scale (P = 0.047, r = -0.288). Adolescents with MDD involves changes in WM functional signals, and these differences in brain regions may increase the risk of suicide.

MRI ankle in juvenile idiopathic arthritis and its comparison with clinical disease activity scores

Objectives: Juvenile idiopathic arthritis (JIA) is a common cause of morbidity and consequent disability among youth up to 16 years of age. Our study aims to image the ankle joints of JIA patients and correlate the findings with the clinical disease activity scores. Juvenile Arthritis Disease Activity Score (JADAS-27) is used by pediatricians to assess disease activity in JIA patients. There are four factors that determine this score – Global assessment of disease activity by the physician as well as patient/parent, joint count with active disease, and erythrocyte sedimentation rate (ESR). However, these clinical scores are dependent on the clinician’s experience and observation and, therefore, subjective. Material and Methods: Thirty patients of either sex with a clinical diagnosis of JIA as per the International League of Association for Rheumatology definition with clinically involved ankle joints were included in the study. Chronic arthritis due to other causes, such as infection, trauma, and so on, was excluded. All clinically diagnosed cases of JIA were subjected to magnetic resonance imaging (MRI) evaluation on Siemens Skyra 3 Tesla High-Resolution MR system using a dedicated coil for the ankle joint. Six sub-joints for each patient are evaluated, namely - The tibiotalar joint, subtalar joint, calcaneocuboid joint, calcaneonavicular joint, naviculocuneiform joint, and tarsometatarsal joint. Image analysis and scoring shall be done for each patient at each joint as per the Juvenile Arthritis MRI SCORE, consisting of the following parameters-synovial hypertrophy score, cartilage lesion score, bone erosion score, and bone marrow change score. Each of these scores is calculated individually based on the percentage of involved bone volume. All individual scores were summed to get the total MRI Score. The data collected were then statistically analyzed. Results: A positive correlation was sought between the JADAS-27 score and the total MRI score with the P-value being 0.03. A positive correlation was also found between the total MRI score and the ESR value of the patient (P - 0.02). Conclusion: MRI findings can be a potential marker of disease activity in JIA patients and these findings could also predict the prognosis accurately in these patients. The findings are objective and comparable to the aforementioned clinical scores.

Depression and Hippocampal Subfield Volume in Older Adults

AbstractBackgroundMajor Depressive Disorder (MDD) is associated with higher risk for developing Alzheimer’s Disease (AD), (Bennett &amp; Thomas, 2014). Both conditions are associated with smaller hippocampal subfield volumes, and both preferentially affect females (Shi et al., 2021). We examined the relationship between depression diagnosis and hippocampal subfield volume, by carrier status for AD genetic risk variant APOE4 and sex. We hypothesized that the association between depression and subfield volume would be stronger in females due to the higher rate of depression.MethodWe examined 1726 cognitively intact older adults from the Health and Aging Brain Study ‐ Health Disparities (HABS‐HD) cohort (Table1) who had available hippocampal high resolution MRI scans (Siemens Skyra or Vida‐3T). Scans were segmented into CA1, CA23DG, and subiculum using Automatic Segmentation of Hippocampal Subfields (ASHS) software and subfield volume was averaged bilaterally. We used separate multiple linear regressions to assess the association between depression and each hippocampal subfield volume, covarying for age, sex, years of education, number of MRI slices segmented, intracranial volume, and scanner. We corrected for multiple comparisons across regions using FDR correction. We also evaluated CA1 and CA23DG volume to depression diagnosis, stratifying by APOE4 positivity and sex and testing for formal interactions.ResultSee Table 2 for results. Depression was associated with smaller CA1 and CA23DG volume across all participants. Depression was associated with smaller CA1 and CA23DG in the APOE4 negative group, but not the APOE4 positive group. The depression by APOE4 interaction was significant for CA23DG volume (𝛽 = 0.25, p = 0.049). Depression was associated with smaller CA1 and CA23DG volumes in males, but not in females, with trend level interaction effects in the CA1 (𝛽 = 0.13, p = 0.095) and CA23DG (𝛽 = 0.17, p = 0.067).ConclusionDepression was associated with smaller CA1 and CA23DG volumes in older adults consistent with past literature. In contrast to our hypotheses, depression was associated with lower hippocampal subregional volumes more in those with lower risk for Alzheimer’s disease (male and APOE4‐ adults).Variability induced by other AD risk factors may mask the relationship between depression and hippocampal subregion volume when AD risk is higher.

Metabolic Syndrome Score is Associated with Lower Myelin in Cognitively Healthy Adults

AbstractBackgroundMetabolic syndrome (MetS) is a cluster of cardiovascular risk factors, including abdominal obesity, glucose intolerance, elevated blood pressure (BP), and dyslipidemia. MetS is a known risk factor for cognitive dysfunction and dementia (Yaffe et al., 2004. YAMA), and has been linked to brain atrophy and altered WM microstructure measured with diffusion tensor MR (Alfaro et al., 2018, Metabolism). The metabolic cost of myelin maintenance makes WM particularly vulnerable to metabolic dysfunction. Here, we aim to explore the relationships between MetS and myelin, as well as test whether WC‐myelin association (Bouhrara et al., 2021, Int J Obes) is independent from systolic BP.MethodSample included 90 cognitively and neurologically healthy adults (Bookheimer et al., 2019, Neuroimage), aged 20 to 79 (M = 53, SD = 17) with 76% women. Additional exclusion criteria included systolic blood pressure &gt;140, BMI&gt;33, and &gt;2 on modified Hachinski Ischemic Scale. Myelin water imaging was collected using a 3T Siemens Skyra with a 32‐channel coil and 3D‐gradient and spin‐echo (GRASE) sequence (1.9×1.9×4mm, TR = 1000ms, echoes = 32, first echo = 10ms, echo spacing = 10ms). Myelin Water Fraction maps were nonlinearly aligned to FMRIB58_FA using TBSS in FSL. MetS score was calculated as a sum of z‐scored waist circumference (WC), systolic BP, BMI, and self‐reports history of elevated cholesterol and glucose.ResultA linear regression analysis with MWF as the dependent variable, adjusting for sex, race, ethnicity, age, and age2, income and education, indicated that greater MetS score was associated with lower MWF in several regions including the genu corpus callosum, anterior corona radiata, and external capsule. WC was negatively associated with whole WM MWF (B = ‐.265, t(79,9) = ‐2.150, p = 0.035) after controlling for the above covariates and systolic BP.ConclusionAssociations between MetS with myelin content were detected especially in the late‐myelinating regions. This aligns with the development‐to‐degeneration hypothesis of WM aging, with lower oligodendrocyte‐to‐axon ratio as a possible factor contributing to metabolic vulnerability of late‐myelinating tracts. We also replicated the WC‐myelin association, although in fewer regions and with smaller effects sizes. Together, our results suggest that different metabolic syndrome components may exert both additive/synergistic, and independent effects on myelin integrity across adulthood.

Generalized Calibrated BOLD fMRI for the Relationship between Cerebral Metabolism and Hypertensive Status

AbstractBackgroundElevated blood pressure levels during mid‐life have been found to be associated with an increased susceptibility to developing dementia later in life, particularly vascular dementia. Quantitative imaging biomarkers, such as Oxygen Extraction Fraction (OEF) and Cerebral Metabolism Rate of Oxygen (CMRO2), can be indicators of impaired cerebral metabolism. Calibrated Blood Oxygen Level Dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) is a multi‐parametric approach utilizing hyperoxic and hypercapnic gas challenges (Figure 1). The impact of hypertension on OEF and CMRO2 has been investigated.MethodA cohort of 84 participants was recruited from the Wake Forest Alzheimer’s Disease Research Center (ADRC) Clinical Core (Table 1). Among all the covariates, participants with prediabetes and diabetes were considered diabetic, and those who exhibited high blood pressure or were using medication to manage hypertension were classified as hypertensive. The MRI was conducted using a 3T Siemens Skyra MRI scanner with a 32‐channel head coil. Dynamic Pseudocontinuous Arterial Spin Labeling (PCASL) was used to acquire cerebral blood flow (CBF) and BOLD images during respiratory challenges with an end‐tidal forcing system. The ROI values in the frontal lobe, temporal lobe, parietal lobe, and occipital lobe regions were chosen. The correlation between hypertensive status and OEF and CMRO2 in the ROI was analyzed with a linear mixed model, with covariates of age, sex, cognitive status, APOE genotype, diabetic status, and hypertensive status.ResultA negative correlation was found between CBF, OEF, and CMRO2 with hypertensive status in frontal lobe region (Figure 2). Statistical significance was observed for OEF and CMRO2 (p = 0.049 and p = 0.028, respectively), indicating the potential influence of hypertensive status on these biomarkers.ConclusionThe study concludes that there is a significant negative association between hypertensive status and both OEF and CMRO2, particularly in the frontal lobe region. The observed reduction in OEF and CMRO2 is not solely due to decreased CBF, but rather complex and multifactorial processes involving vascular remodeling and altered oxygen metabolism. Additional research is necessary to fully understand the underlying pathophysiological mechanisms that link hypertension to decreased OEF and CMRO2, particularly in the context of regional specificity.

A Preliminary Study of Brain Functional Magnetic Resonance Imaging in Text Reading and Comprehension.

Few studies have focused on the changes in human brain function activities caused by reading Chinese characters with different intelligibility and whether it can reflect the understanding and cognitive ability of the human brain. Task-fMRI based on Chinese character reading tasks with different intelligibility was used to explore activated brain regions and their cognitive changes. Volunteers were randomly recruited using advertisements. Forty volunteers were recruited based on strict inclusion and exclusion criteria, and 40 volunteers were recruited. Brain function data of 40 healthy right-handed volunteers in fuzzy/clear Chinese reading tasks were collected using a Siemens Skyra 3.0T magnetic resonance scanner. Data were preprocessed and statistically analyzed using the statistical software SPM12.0 to observe the activation of the cortex and analyze its characteristics and possible changes in cognitive function. Task-fMRI analysis: (1) The main brain regions activated in fuzzy/clear reading tasks were located in the occipital visual cortex (P < 0.001); (2) a paired sample t-test suggested that there was a significant difference in BOLD signals in the brain regions activated by fuzzy/clear reading tasks (P < 0.001, equiv Z = 4.25). Compared with the fuzzy reading task, the brain regions more strongly activated in the clear reading task were mainly located in the right superior frontal gyrus and the bilateral temporal lobe. Compared with the clear reading task, the brain region that was more strongly activated in the fuzzy reading task was mainly located in the right fusiform gyrus. Clear Chinese character information mainly activates the dorsal stream of the visual-spatial network. This reflects the information transmission of the brain after understanding the text content and is responsible for guiding and controlling attention. Fuzzy words that cannot provide clear text content activate the fusiform gyrus of the ventral stream of the visual-spatial network, strengthening the function of orthographic processing.

Assessment of interfraction dose variation in pancreas SBRT using daily simulation MR images

Pancreatic Cancer is associated with poor treatment outcomes compared to other cancers. High local control rates have been achieved by using hypofractionated stereotactic body radiotherapy (SBRT) to treat pancreatic cancer. Challenges in delivering SBRT include close proximity of several organs at risk (OARs) and target volume inter and intra fraction positional variations. Magnetic resonance image (MRI) guided radiotherapy has shown potential for online adaptive radiotherapy for pancreatic cancer, with superior soft tissue contrast compared to CT. The aim of this study was to investigate the variability of target and OAR volumes for different treatment approaches for pancreatic cancer, and to assess the suitability of utilizing a treatment-day MRI for treatment planning purposes. Ten healthy volunteers were scanned on a Siemens Skyra 3 T MRI scanner over two sessions (approximately 3 h apart), per day over 5 days to simulate an SBRT daily simulation scan for treatment planning. A pretreatment scan was also done to simulate patient setup and treatment. A 4D MRI scan was taken at each session for internal target volume (ITV) generation and assessment. For each volunteer a treatment plan was generated in the Raystation treatment planning system (TPS) following departmental protocols on the day one, first session dataset (D1S1), with bulk density overrides applied to enable dose calculation. This treatment plan was propagated through other imaging sessions, and the dose calculated. An additional treatment plan was generated on each first session of each day (S1) to simulate a daily replan process, with this plan propagated to the second session of the day. These accumulated mock treatment doses were assessed against the original treatment plan through DVH comparison of the PTV and OAR volumes. The generated ITV showed large variations when compared to both the first session ITV and daily ITV, with an average magnitude of 22.44% ± 13.28% and 25.83% ± 37.48% respectively. The PTV D95 was reduced by approximately 23.3% for both plan comparisons considered. Surrounding OARs had large variations in dose, with the small bowel V30 increasing by 128.87% when compared to the D1S1 plan, and 43.11% when compared to each daily S1 plan. Daily online adaptive radiotherapy is required for accurate dose delivery for pancreas cancer in the absence of additional motion management and tumour tracking techniques.

P.114 When functional neuroimaging is ambiguous for language localization: a case for Wada testing

Background: To localize cortical speech areas, methods such as fMRI are commonly used, but the Wada test can also determine whether a region is critical to the particular task. We report a case of a left-handed patient with a left frontal tumour in whom fMRI language paradigms produced both left and right Broca’s and Wernicke’s areas. Methods: All imaging used a 3 Tesla Siemens Skyra scanner. The patient performed five speech tasks: word reading, picture naming, semantic questions, pseudohomophone reading, and word generation. All preprocessing and statistical analyses for functional images were performed using Brain Voyager QX. Results: The fMRI results revealed right hemisphere dominance for language processing. A Wada test was performed in order to confirm whether the regions in the left hemisphere were critical to speech. The patient experienced speech arrest during the Wada test, thus confirming that despite bilateral speech activation, the left hemisphere speech regions are required for speech production. Conclusions: This case emphasizes the importance of preoperative fMRI in assessing the location of eloquent cortices adjacent to a tumour and the Wada test is still warranted for examining necessity of left hemisphere language regions when fMRI fails to show clear left-lateralization.

Clinical validation of MR imaging time reduction for substitute/synthetic CT generation for prostate MRI-only treatment planning.

Radiotherapy treatment planning based only on magnetic resonance imaging (MRI) has become clinically achievable. Though computed tomography (CT) is the gold standard for radiotherapy imaging, directly providing the electron density values needed for planning calculations, MRI has superior soft tissue visualisation to guide treatment planning decisions and optimisation. MRI-only planning removes the need for the CT scan, but requires generation of a substitute/synthetic/pseudo CT (sCT) for electron density information. Shortening the MRI imaging time would improve patient comfort and reduce the likelihood of motion artefacts. A volunteer study was previously carried out to investigate and optimise faster MRI sequences for a hybrid atlas-voxel conversion to sCT for prostate treatment planning. The aim of this follow-on study was to clinically validate the performance of the new optimised sequence for sCT generation in a treated MRI-only prostate patient cohort. 10 patients undergoing MRI-only treatment were scanned on a Siemens Skyra 3T MRI as part of the MRI-only sub-study of the NINJA clinical trial (ACTRN12618001806257). Two sequences were used, the standard 3D T2-weighted SPACE sequence used for sCT conversion which has been previously validated against CT, and a modified fast SPACE sequence, selected based on the volunteer study. Both were used to generate sCT scans. These were then compared to evaluate the fast sequence conversion for anatomical and dosimetric accuracy against the clinically approved treatment plans. The average Mean Absolute Error (MAE) for the body was 14.98 ± 2.35 HU, and for bone was 40.77 ± 5.51 HU. The external volume contour comparison produced a Dice Similarity Coefficient (DSC) of at least 0.976, and an average of 0.985 ± 0.004, and the bony anatomy contour comparison a DSC of at least 0.907, and an average of 0.950 ± 0.018. The fast SPACE sCT agreed with the gold standard sCT within an isocentre dose of -0.28% ± 0.16% and an average gamma pass rate of 99.66% ± 0.41% for a 1%/1 mm gamma tolerance. In this clinical validation study, the fast sequence, which reduced the required imaging time by approximately a factor of 4, produced an sCT with similar clinical dosimetric results compared to the standard sCT, demonstrating its potential for clinical use for treatment planning.

Cognitive impairment and small vessel disease in atrial fibrillation

Objective : to evaluate the impact of various forms of atrial fibrillation (AF) on the development of mild cognitive impairment (MCI) and cerebral small vessel disease. Patients and methods . The study included 31 patients with AF (paroxysmal form – 22 patients, permanent form – 9 patients). Arterial hypertension was diagnosed in 26 patients and diabetes mellitus in 6 patients. All patients were taking direct oral anticoagulants (DOACs). Patients underwent cognitive testing, screening ultrasound examination of the main arteries of the head and neck, MRI on a Siemens Skyra 3 T tomograph according to a protocol including diffusion tensor imaging and perfusion determination. To create a control group of healthy elderly individuals, the open database of clinical and MR data OASIS 3 was used that retrospectively evaluated more than 1000 people over a period of 30 years. Participants whose cognitive status was assessed clinically as "normal cognitive function" were selected. Results and discussion . The frequency of MCI and indicators of cognitive tests did not differ in groups of patients with permanent and paroxysmal forms of AF. The distribution of foci of hyperintense white matter, the thickness of the cerebral cortex also did not differ in patients with different forms of AF. The neuroimaging pattern of cerebral small vessel disease in AF patients without stroke was consistent with population controls. Conclusion . Prescribing DOACs to patients reduces the risk of cognitive impairment of vascular origin development due to the clear and predictable effect of this class of drugs that prevent the development of cerebral embolism.

PEDIATRIC SPINAL DYSRAPHISM ON MAGNETIC RESONANCE IMAGING: TRENDS IN A TERTIARY CARE HOSPITAL IN NORTH INDIA

Background: Spine and spinal cord development is governed by intricate genetic mechanisms and any deviation from the normal embryological cascade during 2-6 gestational weeks causes imperfect fusion of midline mesenchymal, bony and neural structures causing spinal dysraphism. Imaging plays a pivotal role in their evaluation as many patients present with concurrent anomalies that need to be corrected simultaneously to avoid repeat surgeries. To demonstrate the spectrum of MRI ndings of spinal dysraphi Aim: Settings and design: sm. A cross sectional observational study was done in 36 pediatric patients with known or suspected spinal dysraphism on 3T MRI. MRI was Materials And Methods: performed using Siemens Skyra 3T MRI. In this study comprising of 36 patients, mean age Results: was 37.1months (3 years 1month) with minimum age of 4 days and maximum age of 18 years. Children of age less than 5 years were maximally affected. A female predominance was noted with male: female ratio of 0.9:1. Open spinal dysraphism (55.6%) was more common than closed dysraphism (44.4%). The most common dysraphism was myelomeningocele. Among open dysraphism, we also encountered 1 case each of hemimyelomeningocele and myelocele. Among closed defects, split cord malformation was most common (19.4%) as it was present with other dysraphic defects (called complex spina bida), followed by lipomyelocele (11.1%) and dermal sinus (11.1%). Among 7 cases of split cord malformation, type II (6 cases; 85.7%) was more common than type I (1 case; 14.3%). Other cases of closed dysraphism were lipomyelomeningocele, meningocele, terminal myelocystocele, intradural lipoma, lar lipoma and caudal regression syndrome. MRI is an excelle Conclusion: nt modality for dening the characteristic imaging features of each dysraphism to give a composite diagnosis.

Friday, June 17, 202212:30 PM - 1:30 PM PHSOR01 Presentation Time: 12:30 PM: Characterization of a Novel Multi-Modality Imaging Phantom for Ultrasound Interstitial Needle Guidance for High Dose Rate Gynecological Brachytherapy

<h3>Purpose</h3> To design, manufacture, and validate a realistic female pelvic phantom for multi-modality imaging on CT, MRI, and transrectal ultrasound (TRUS) to guide and track interstitial needles during an HDR gynecological procedure using a commercial needle tracking system. <h3>Materials and Methods</h3> The pelvic phantom was designed using 3D Slicer and Autodesk Fusion360 to model an average uterus from a 50 patient data study¹, a vaginal canal from KleenSpec speculum dimensions, and a rectum to accommodate a BK 8848 endocavity biplane US probe. A 1.5 cm x 3.0 cm x 1.25 cm (WxLxH) half ellipsoid CTV_HR was also designed. Modeled anatomy was Boolean subtracted from rectangular solids to create a negative space mold. An Ultimaker S3 printer was used to print the 3D molds using polylactic acid. Smooth-On Silicone 20T was used as a casting agent for the uterus, cervix, vaginal canal, and rectum based on their similar mechanical properties. A 3D printed box was constructed to house the designed anatomy to provide structural integrity and allow the insertion of a speculum, tandem and ovoid applicator, needles, and TRUS probe. Agarose gelatin with glycerol and cellulose was used as a background medium to surround and support the pelvic anatomy and to allow for US propagation. After manufacturing, the phantom was imaged with CT to identify potential imperfections that might impact its visualization on US images. Following initial CT validation, the tracking system with the endorectal probe was used to image the phantom. US images from a 180 degree sweep were acquired and a 3D US volume was generated that allowed uterus contouring to aid in real-time insertion of 2 needles (Needle1 in CTV_HR, Needle2 in uterus). After insertion, the phantom was imaged with a Siemens Biograph mCT using a slice thickness of 0.6 mm and with a Siemens Skyra 3T MRI using the institutional HDR brachytherapy MR imaging protocol with T1 and T2 weighted sequences. The CTV_HR and uterus were contoured on CT and MR images and their dimensions were checked against the CAD model. <h3>Results</h3> Fig. 1a shows the CAD model for the anatomy (uterus dimensions of 7.87 cm x 4.45 cm, rectum diameter of 2 cm), the encasing box, and the casting mold used to fabricate the phantom. The volumes of the CTV_HR and uterus reconstructed from the CAD model were 3 cm³ and 76.8 cm³, respectively. Figs. 1b-c show sagittal CT and US images of the phantom. The measurements of uterus dimensions (7.87 cm x 4.4 cm) and rectum diameter (2 cm) on the sagittal CT image demonstrated a high degree of fidelity with the CAD model. The uterus volume (77.1 cm³) reconstructed from CT images was also very similar to that from the CAD model. Fig. 1d shows the phantom setup for US imaging using the needle tracking system and BK 8848 endorectal probe. Representative sagittal images through the phantom at the location of the 2 implanted needles are shown in Figs. 1e-h (CT, T1w MRI, T2w MRI, and US, respectively). The overall volumes CTV_HR (3.2 cm³) and uterus (82.9 cm³) reconstructed from the T2w MR images also agreed with those from the CAD model. Fig. 1f shows axial and sagittal images of the 3D US volume from the tracking software (uterus contour in green). The generated volume allowed for intraoperative needle insertion guidance. <h3>Conclusions</h3> The manufactured pelvic phantom allows for accurate visualization with multiple imaging modalities and is conducive to applicator and needle insertion. The phantom is low cost and can be reproducibly manufactured with the 3D molding process. Our initial experiments demonstrate the ability to integrate the phantom with the commercial tracking system for future needle tracking validation studies. 1. Campelo, et al. (2020). Brachytherapy, 19(6), 767-776

Asynchronous magnetic resonance elastography: Shear wave speed reconstruction using noise correlation ofincoherent waves.

The noninvasive measurement of biological tissue elasticity is an evolving technology that enables the robust characterization of soft tissue mechanics for a wide array of biomedical engineering and clinical applications. We propose, design, and implement here a new MRI technique termed asynchronous magnetic resonance elastography (aMRE) that pushes the measurement technology toward a driverless implementation. This technique can be added to clinical MRI scanners without any additional specialized hardware. Asynchronous MRE is founded on the theory of diffuse wavefields and noise correlation previously developed in ultrasound to reconstruct shear wave speeds using seemingly incoherent wavefields. Unlike conventional elastography methods that solve an inverse problem, aMRE directly reconstructs a pixel-wise mapping of wave speed using the spatial-temporal statistics of the measured wavefield. Incoherent finger tapping served as the wave-generating source for all aMRE measurements. Asynchronous MRE was performed on a phantom using a Siemens Prismafit as an experimental validation of the theory. It was further performed on thigh muscles as a proof-of-concept implementation of in vivo imaging using a Siemens Skyra scanner. Numerical and phantom experiments show an accurate reconstruction of wave speeds from seemingly noisy wavefields. The proof-of-concept thigh experiments also show that the aMRE protocol can reconstruct a pixel-wise mapping of wave speeds. Asynchronous MRE is shown to accurately reconstruct shear wave speeds in phantom experiments and remains at the proof-of-concept stage for in vivo imaging. After further validation and improvements, it has the potential to lower both the technical and monetary barriers of entry to measuring tissue elasticity.

Two fully automated data-driven 3D whole-breast segmentation strategies in MRI for MR-based breast density using image registration and U-Net with a focus on reproducibility

Presence of higher breast density (BD) and persistence over time are risk factors for breast cancer. A quantitatively accurate and highly reproducible BD measure that relies on precise and reproducible whole-breast segmentation is desirable. In this study, we aimed to develop a highly reproducible and accurate whole-breast segmentation algorithm for the generation of reproducible BD measures. Three datasets of volunteers from two clinical trials were included. Breast MR images were acquired on 3 T Siemens Biograph mMR, Prisma, and Skyra using 3D Cartesian six-echo GRE sequences with a fat-water separation technique. Two whole-breast segmentation strategies, utilizing image registration and 3D U-Net, were developed. Manual segmentation was performed. A task-based analysis was performed: a previously developed MR-based BD measure, MagDensity, was calculated and assessed using automated and manual segmentation. The mean squared error (MSE) and intraclass correlation coefficient (ICC) between MagDensity were evaluated using the manual segmentation as a reference. The test-retest reproducibility of MagDensity derived from different breast segmentation methods was assessed using the difference between the test and retest measures (Δ2-1), MSE, and ICC. The results showed that MagDensity derived by the registration and deep learning segmentation methods exhibited high concordance with manual segmentation, with ICCs of 0.986 (95%CI: 0.974-0.993) and 0.983 (95%CI: 0.961-0.992), respectively. For test-retest analysis, MagDensity derived using the registration algorithm achieved the smallest MSE of 0.370 and highest ICC of 0.993 (95%CI: 0.982-0.997) when compared to other segmentation methods. In conclusion, the proposed registration and deep learning whole-breast segmentation methods are accurate and reliable for estimating BD. Both methods outperformed a previously developed algorithm and manual segmentation in the test-retest assessment, with the registration exhibiting superior performance for highly reproducible BD measurements.

IMG-06. Comparing between MR spectroscopy done at 1.5T and 3T

INTRODUCTION: In hospitals with heavily utilised MRI scanners, it may not be possible to schedule the patient on 1 particular scanner for all scans and thus this project was carried out to determine if there is any significant difference in the spectroscopy profile between 1.5 T and 3T MRI scanners late year 2021. AIM: To describe the MR spectroscopy profile of normal brain tissue performed on 1.5T and 3T MRI scanners in KK Women’s and Children’s Hospital. METHODS: Three healthy adult volunteers with normal body mass index underwent MRI brain scans after informed consent in this Institute Review Board approved study. MRI brain scans were performed on 1.5T General Electric MRI scanner and 3T Siemens Skyra MRI scanner 1 week apart. NAA/Cr, Cho/Cr and Cho/ NAA values were obtained from the right and left cerebral hemispheres. RESULTS: Average NAA/Cr in the right cerebral hemisphere is 2.06+/-0.10 at 1.5T. Average NAA/Cr in the left cerebral hemisphere is 2.01+/-0.23 at 1.5T. Average NAA/Cr in the right cerebral hemisphere is 1.56+/-0.09 at 3T. Average NAA/Cr in the left cerebral hemisphere is 1.81+/-0.29 at 3T. Average Cho/Cr in the right cerebral hemisphere 1.06+/-0.14 at 1.5T. Average Cho/Cr in the left cerebral hemisphere is 1.11+/-0.22 at 1.5T. Average Cho/Cr in the right cerebral hemisphere is 0.90+/-0.05 at 3T. Average Cho/Cr in the left cerebral hemisphere is 0.95+/-0.27 at 3T. Average Cho/NAA in the right cerebral hemisphere is 0.51+/-0.06 at 1.5T. Average Cho/NAA in the left cerebral hemisphere is 0.58+/-0.00 at 1.5T. Average Cho/NAA in the right cerebral hemisphere is 0.55+/-0.05 at 3T. Average Cho/NAA in the left cerebral hemisphere is 0.52+/-0.07 at 3T. CONCLUSION: MR spectroscopy values obtained from 1.5T and 3T MRI scanners show no significant difference(P>0.05).

Abstract P3-03-03: Quantitative multiparametric MRI predicts response to neoadjuvant therapy in the community setting

Abstract Background: Early and accurate prediction of response to neoadjuvant therapy (NAT) would empower personalization of breast cancer treatment regimens based on expected response. Noninvasive, quantitative dynamic contrast-enhanced (DCE-MRI) and diffusion-weighted magnetic resonance imaging (DW-MRI), when performed during the course of NAT, can accurately predict the ultimate pathological response. While these techniques have been incorporated into clinical trials in the academic setting, they have not yet been translated to the community setting, where most cancer patients receive their care. Implementation of quantitative MRI in the community setting widely expands the potential impact it can provide by 1) allowing community settings to participate in clinical trials that require quantitative MRI, and 2) advancing quantitative MRI towards standard-of-care for prediction of response in breast cancer. Methods: Women with locally advanced breast cancer (N = 28) were imaged four times during the course of NAT: 1) prior to the start of NAT, 2) after 1 cycle of NAT, 3) after 2-4 cycles of NAT, and 4) 1 cycle after MRI #3. Imaging data was acquired on 3T Siemens Skyra scanners equipped with breast coils and sited in a community hospital and radiology clinic, respectively. DW-MRI and DCE-MRI were acquired over 10 slices of 5 mm thickness. DW-MRI was acquired with diagonal monopolar diffusion-encoding gradients with b-values of 0, 200, and 800 s/mm2 in a total scan time of 1 minute 39 seconds. Voxel wise tumor cellularity was quantified using the apparent diffusion coefficient (ADC). For DCE-MRI, a gadolinium-based contrast agent was administered intravenously at 2 mL/sec after the acquisition of baseline scans. DCE-MRI data was acquired dynamically with a temporal resolution of 7.27 seconds for a total acquisition time of 8 minutes. The volume transfer constant Ktrans was calculated using Patlak analysis of DCE-MRI data to characterize the tumor vasculature. The tumor was semi-automatically segmented using a manually drawn region of interest followed by fuzzy c-means clustering of DCE-MRI data to identify a functional tumor volume. Measurements of tumor volume were combined with both ADC and Ktrans to yield metrics of tumor cellularity and bulk tumor flow, respectively. Results: Women who achieved pathological complete response at the time of surgery (pCR; n=8) displayed significantly different treatment-induced changes in MRI-derived tumor parameters versus women who did not achieve pCR (non-pCR, n=20). After 1 cycle of NAT, women who achieved pCR had smaller functional tumor volume and lower cellularity (p &amp;lt; 0.05) than non-pCR study participants. At the third and fourth MRI, tumor volume, ADC, Ktrans, cellularity, and bulk tumor flow were all significantly different between the pCR and non-pCR cohorts (p &amp;lt; 0.05). Of note, longest tumor diameter was not predictive of pCR at any time point in this study. Conclusions: This study demonstrates that quantitative DCE- and DW-MRI can be implemented successfully in community care facilities within standard-of-care settings for imaging locally advanced breast cancer. Metrics extracted from the change in DW-MRI (ADC) and DCE-MRI (Ktrans) can accurately predict pathological complete response to neoadjuvant therapy and may be more sensitive to tumor response than the RECIST criteria. Furthermore, incorporating quantitative metrics with tumor volume further increases the ability to predict pathological response to NAT in locally advanced breast cancer. While there are still challenges to address to effectively implement these quantitative metrics into the clinical workflow, this study is first in its kind to transition a decade’s worth of quantitative MRI advancements from academic settings into standard-of-care. Citation Format: John Virostko, Anna G Sorace, Kalina P Slavkova, Anum S Kazerouni, Angela M Jarrett, Julie C DiCarlo, Stefanie Woodard, Sarah Avery, Boone W Goodgame, Debra Patt, Thomas E Yankeelov. Quantitative multiparametric MRI predicts response to neoadjuvant therapy in the community setting [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-03-03.

Abstract P3-02-09: Three timepoint pharmacokinetic modeling to incorporate within standard of care MRI breast exams

Abstract Background: Standard of care (SOC) breast MRI exams typically acquire 4-7 frames of dynamic contrast-enhanced MRI (DCE-MRI) for cancer screening and staging. Post-contrast images depict lesion spiculations and boundaries to identify and characterize tumors. Pharmacokinetic (PK) analysis of DCE-MRI involves modeling blood flow to the lesion and surrounding tissue and has shown promise in diagnosis and prediction of therapeutic response. Currently, SOC DCE-MRI requires ~60-90 seconds per volume for images with sufficient quality and spatial resolution. However, PK analysis of DCE-MRI requires faster time course sampling. For this reason, PK modeling is limited to research scans with lower spatial resolution and higher temporal resolution. PK modeling would improve feedback of treatment response, and implementation in the SOC exam would increase imaging trial participation. In this study, we tested the estimation of Ktrans, a mixed perfusion and permeability PK parameter, from three images at optimal time points after contrast agent (CA) injection, and compared it to the Ktrans estimation from analysis of the full-length time course.. Methods: Women (N=23) with newly diagnosed invasive breast cancers who were eligible for neoadjuvant therapy (NAT) were scanned with a research MRI protocol as part of a treatment-monitoring study. Images acquired prior to the start of NAT were used. MRI was performed on 3.0T Siemens Skyra scanners at two sites with bilateral breast coils. The research protocol included ten sagittal slices centered about the primary tumor. The DCE-MRI images came from a fast sequence with 1.3 × 1.3 × 5.0 mm resolution acquired at 7.3 seconds per frame (66 frames total,) with a gadolinium-based CA injected one minute into the scan. A population arterial input function was used to implement a mathematical graph-based search of possible tissue CA concentration curves from the expected range of PK parameters. The search results gave a set of three optimized sub-sampled timepoints, Topt, from the full set of sample times, Tfull, at which to best sample the CA concentration curves to optimally estimate PK values. The imaging data was analyzed to find one parameter map from image times Tfull, and another from the subset of images at times Topt. The difference in Ktrans was computed at each parameter map voxel, and the concordance correlation coefficient (CCC) was computed per patient to determine agreement. The median Ktrans values were also compared for each patient. Results: The graph-based search of CA concentration curves found optimal times Topt of 37, 66, and 153 seconds after injection. The averaged values over all patients for median and maximum Ktrans from the original Tfull image set were 0.07 and 0.5 (min)-1. The average difference in Ktrans values between the Topt and Tfull sets was 0.02 (min)-1. When the median Ktrans values for each patient were compared, the average difference in median Ktrans values was 15% +/- 9%. The concordance correlation coefficients comparing the Topt and Tfull -sampled parameter maps for each patient were 0.89 +/- 0.12, showing high agreement. Discussion: This retrospective analysis suggests that it is possible to estimate PK parameters from a few properly selected post-contrast images inserted into a SOC DCE-MRI exam. The combination of optimal timing with fast acquisition techniques for high-resolution imaging could be used to provide quantitative data while preserving post-contrast images with the necessary spatial resolution for clinical reading. Importantly, the test images were acquired in the community setting with widely available MRI hardware, further indicating the potential for integration with SOC exams. Funding: NCI U24 CA226110, NCI U01 CA174706, NCI U01 CA142565, CPRIT RR160005 Citation Format: Julie C DiCarlo, Angela M Jarrett, Anum S Kazerouni, John Virostko, Anna G Sorace, Kalina P Slavkova, Debra Patt, Boone W Goodgame, Sarah Avery, Thomas E Yankeelov. Three timepoint pharmacokinetic modeling to incorporate within standard of care MRI breast exams [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-02-09.

Cardiovascular risk factors, white matter hyperintensities and executive function: Difference among Mexican Americans and non‐Hispanic whites

AbstractBackgroundCardiovascular risk factors (CVRF) differ between ethnicities but is not clear if the relationship with white matter hyperintensities (WMH) and executive function is also different. The purpose of this study was to examine the prevalence of cardiovascular risk factors and their effect on WMH and executive function in a sample of Non‐Hispanic Whites (NHW) and Mexican American (MA) elders.MethodWe studied 1100 (585 NHW, 515 MA) cognitively normal subjects from the Health and Aging Brain Study (HABS‐HD) with signed consent, 3T MRI (Siemens Skyra), clinical evaluation, and cognitive testing. WMH volume was measured from FLAIR using the Statistical Parametric Mapping (SPM) Lesion Segmentation Tool. Linear regression was used to predict the effect of CVRF on WMH. Log transformed WMH adjusted for intracranial volume (derived from Freesurferv6.0 analysis of T1 MPRAGE) were used to predict Trails B (executive function). Age, sex, and education were entered as covariates in the models.ResultSixty‐three percent of the sample were female. MA were significantly younger (mean age 62.6 vs 68.8), less educated (mean education years 9.84 vs 15.64), and had smaller WMH volumes (‐0.13 vs 0.02) than NHW. There was no difference on Trails B scores. MA had a higher prevalence of diabetes and obesity (p=&lt;0.0001), but the prevalence of hypertension and dyslipidemia did not differ among the groups. WMH volume was associated with hypertension in both groups (p=&lt;0.001), while the association with diabetes was only present on MA (p=&lt;0.001). Dyslipidemia and obesity were not associated with WMH volume in any group. WMH predicted Trails B scores in NHW (B = ‐0.13, t =‐4.29, p = &lt;0.001), and MA (B = ‐0.17, t = ‐3.25, p = 0.001). Results remained significant after adjusting for age, sex, education, and CVRF.ConclusionOur findings suggest that the association of CVRF with WMH differs among MA and NHW. Executive function was related to WMH volume in both groups, but it is likely that for MA a metabolic component is more important. Ethnicity should be considered when assessing the association of CVRF, small vessel disease, and cognition.

Racial differences in dementia‐related pathology underlying cognitive decline: The Multi‐Ethnic Study of Atherosclerosis (MESA)

AbstractBackgroundRacial differences in dementia‐related pathology are purported to underlie health disparities in Alzheimer’s disease and related disorders. We examined the prevalence and relevance of neuroimaging biomarkers of cerebral small vessel disease (cSVD), and β‐amyloid (Aβ) deposition in cognitive decline and impairment among a diverse cohort of older adults.MethodParticipants at the Wake Forest MESA site were recruited at Exam 6 (2016‐19) to receive additional detailed cognitive testing, cognitive adjudication, and multimodal neuroimaging. Brain MRI on 3T Siemens Skyra, included T1, SWI, FLAIR and NODDI sequences. Total gray matter and white matter hyperintensities (WMH) volumes were adjusted for intracranial volume. A single neuroradiologist graded vascular lesions, including cerebral microbleeds, large and lacunar infarcts. Cognitive decline was measured by the Cognitive Abilities Screening Instrument (CASI) at Exam 5 (2010‐12) and Exam 6 (2016‐19). A subset of 157 participants completed Aβ‐PET at Exam 6 to quantify Aβ burden and positivity (PiB SUVR ≥1.21). Multivariable linear and logistic regression modeled neuroimaging parameters with change in CASI and cognitive status adjusted for age, gender, education, and APOE genotype, considering potential interactions by race.ResultThe imaging sample included 252 participants (53% African‐American and 47% White; aged 72±7 years; 58% women, Table 1). 27% of participants were adjudicated to have mild cognitive impairment (MCI) and 4% had dementia. Aβ positivity (36%) and cSVD (microbleeds in 37% and lacunes in 32%) were common and did not differ by race. Further, temporal lobe cortical thickness and WMH volumes did not differ by race. Lower total gray matter volume, higher WMH volumes, and lower temporal lobe cortical thickness were consistently associated with greater cognitive decline and impairment across racial groups (Table 2). Significant interactions between race and imaging biomarkers with cognitive decline and impairment observed for: greater NODDI Free Water only in White participants and microbleeds and Aβ only in African‐American participants.ConclusionImaging biomarkers indicative of cSVD and Aβ are common in older adults. These biomarkers were not more prevalent in African‐American than White older adults as previously reported; however, they appear to be more strongly related to cognitive decline and impairment among African‐Americans.

Advanced diffusion‐MRI models reveals sex‐specific differences in white matter organization in patients with mild cognitive impairment

AbstractBackgroundRecent literature suggests that free‐water corrected (fiso) diffusion MRI (dMRI) measures provide higher sensitivity as compared to conventional single‐tensor (ST) dMRI measures to understand white‐matter (WM) changes due to neurodegeneration. However, fiso‐corrected dMRI measures are still biased at crossing‐fiber regions (CFR) of WM which are shown to be around 90% of the total WM voxels with conventional dMRI data acquisition. In this study, we systematically compared dMRI measures from ST‐dMRI, fiso‐corrected ST‐dMRI measures, and measures from advanced dMRI models such as Diffusion Kurtosis Imaging (DKI) and Neurite Orientation Distribution and Density Imaging (NODDI) which are sensitive to CFRs. We hypothesize that these advanced dMRI models will be sensitive in understanding sex‐specific WM organizational changes at regional level in patients with Alzheimer’s disease (AD)‐related mild cognitive impairment (MCI).Method40 healthy controls [HC; 21 Females (F), 19 Males (M)] and 38 MCI participants [13F, 25 M] were recruited at our center. MCI diagnoses were based on expert consensus between a neurologist (AR) and a neuropsychologist (JC) using results of a neuropsychological test battery and the Clinical Dementia Rating (CDR) interview. Isotropic 1.5mm3 multi‐shell dMRI (b‐values=500s/mm2, 1000s/mm2, and 2500s/mm2) each with identical 71 diffusion‐encoding directions was acquired on a 3T Siemens Skyra scanner for every participant using the CMRR sequence. 8 uniformly interspersed non‐diffusion‐weighted (b0) images were also acquired in the same run. ST, fiso‐corrected, DKI, and NODDI dMRI measures were estimated for every brain voxel in‐house using the standard analytic tools. WM was skeletonized using FSL tools and statistical comparisons were done non‐parametrically using PALM tools. GLM was utilized to test for sex‐specific group effect. Significance was established at family‐wise error correction (FWE) pcorr&lt;0.05.ResultThalamocortical tracts of males in both HC and MCI showed a significantly higher axonal kurtosis (AK) and orientation density (ODI) derived from DKI and NODDI when compared to within‐group females. DKI also revealed presence of higher axonal water fraction (AWF) along the entire WM‐tracts between HC‐female and HC‐male, and lower mean kurtosis (MK) along the thalamic‐cortical tracts in HC‐females as compared to MCI‐females.ConclusionAdvanced dMRI‐models are sensitive to understand sex‐specific WM disorganization due to healthy ageing and MCI.