MRI Mapping Research Articles

Short post-injection seizure duration is associated with reduced power of ictal brain perfusion SPECT to lateralize the seizure onset zone.

The aim of this study was to assess the impact of the post-injection electrical seizure duration on the identification of the seizure onset zone (SOZ) in ictal brain perfusion SPECT in presurgical evaluation of drug-resistant epilepsy. 176 ictal SPECT performed with 99mTc-HMPAO (n = 140) or -ECD (n = 36) were included retrospectively. Visual interpretation of the SPECT images (together with individual MRI and statistical hyperperfusion maps) with respect to lateralization (right, left, none) and localization (temporal, frontal, parietal, occipital) of the SOZ was performed by 3 independent readers. Between-readers agreement was characterized by Fleiss' κ. An ictal SPECT was considered "lateralizing" if all readers agreed on right or left hemisphere. It was considered "localizing" if it was lateralizing and all readers agreed on the same lobe within the same hemisphere. The impact of injection latency and post-injection seizure duration on the proportion of lateralizing/localizing SPECT was tested by ANOVA with dichotomized (by the median) injection latency and post-injection seizure duration as between-subjects factors. Median [interquartile range] (full range) of injection latency and post-injection seizure duration were 30 [24, 40] (3-120) s and 50 [27, 70] (-20-660) s, respectively. Fleiss' κ for lateralization of the SOZ was largest for the combination of early (< 30s) injection and long (> 50s) post-injection seizure duration (κ = 0.894, all other combinations κ = 0.659-0.734). Regarding Fleiss' κ for localization of the SOZ in the 141 (80.1%) lateralizing SPECT, it was largest for early injection and short post-injection seizure duration (κ = 0.575, all other combinations κ = 0.329-0.368). The proportion of lateralizing SPECT was lower with short compared to long post-injection seizure duration (estimated marginal means 74.3% versus 86.3%, p = 0.047). The effect was mainly driven by cases with very short post-injection seizure duration ≤ 10s (53.8% lateralizing). Injection latency in the considered range had no significant impact on the proportion of lateralizing SPECT (p = 0.390). The proportion of localizing SPECT among the lateralizing cases did not depend on injection latency or post-injection seizure duration (p ≥ 0.603). Short post-injection seizure duration is associated with a lower proportion of lateralizing cases in ictal brain perfusion SPECT.

Fast T1 mapping MRI in preclinical and clinical settings using subspace-constrained joint-domain reconstructions

This work aims to develop fast T1 mapping methods for preclinical and clinical scanners based on subspace-constrained reconstructions. Two sequences are explored for rapid T1 characterizations: 1) Interleaved spatiotemporal encoding incorporating variable repetition times. 2) Inversion recovery gradient echo with random sampling of the phase-encoding (PE) dimension. For both sequences, the subspace reconstruction of the signal recovery was applied, to jointly reconstruct the down-sampled images while characterizing the T1 relaxation. In vivo scans on human brains and abdomens confirmed the efficiency of the proposed methods, including compatibility with breath-holding. In addition, Scans on animals with abdominal tumors and dynamic contrast-enhanced T1 mapping on kidneys support the applicability of the proposed methods also in preclinical settings.

Histogram analysis of MR quantitative parameters: are they correlated with prognostic factors in prostate cancer?

To investigate the correlation between quantitative MR parameters and prognostic factors in prostate cancer (PCa). A total of 186 patients with pathologically confirmed PCa who underwent preoperative multiparametric MRI (mpMRI), including synthetic MRI (SyMRI), were enrolled from two medical centers. The histogram metrics of SyMRI [T1, T2, proton density (PD)] and apparent diffusion coefficient (ADC) values were extracted. The Mann‒Whitney U test or Student's t test was employed to determine the association between these histogram features and the prognostically relevant factors. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the differentiation performance. Spearman's rank correlation coefficients were calculated to determine the correlations between histogram parameters and the International Society of Urological Pathology (ISUP) grade group as well as pathological T stage. Significant correlations were found between the histogram parameters and the ISUP grade as well as pathological T stage of PCa. Among these histogram parameters, ADC_minimum had the strongest correlation with the ISUP grade (r = -0.481, p<0.001), and ADC_Median showed the strongest association with pathological T stage (r = -0.285, p=0.008). The ADC_10th percentile exhibited the highest performance in identifying clinically significant prostate cancer (csPCa) (AUC 0.833; 95% CI 0.771-0.883). When discriminating between the status of different prognostically relevant factors, a significant difference was observed between extraprostatic extension-positive and -negative cancers with regard to histogram parameters of the ADC map (10th percentile, 90th percentile, mean, median, minimum) and T1 map (minimum) (p=0.002-0.032). Moreover, histogram parameters of the ADC map (90th percentile, maximum, mean, median), T2 map (10th percentile, median), and PD map (10th percentile, median) were significantly lower in PCa with perineural invasion (p=0.009-0.049). The T2 values were significantly lower in patients with seminal vesicle invasion (minimum, p=0.036) and positive surgical margin (10th percentile, 90th percentile, mean, median, and minimum, p=0.015-0.025). Quantitative histogram parameters derived from synthetic MRI and ADC maps may have great potential for predicting the prognostic features of PCa.

Cerebral Tau Deposition in Comorbid Progressive Supranuclear Palsy and Amyotrophic Lateral Sclerosis: An [18F]-Flortaucipir and 7T MRI Study

Introduction: Progressive supranuclear palsy (PSP) is a four-repeat tauopathy characterized by multiple clinicopathologic subtypes. Advanced neuroimaging techniques have shown an early ability to distinguish PSP subtypes noninvasively for improved diagnosis. This study utilized tau PET imaging and MRI techniques at 7T to determine the neuroimaging profile of a participant with comorbid PSP and amyotrophic lateral sclerosis (ALS). Method: [18F]-flortaucipir PET imaging was performed on one participant with PSP-ALS, one participant with typical PSP (Richardson’s syndrome; PSP-RS), and 15 healthy control volunteers. Standardized uptake value ratio (SUVR) in each brain region was compared between PSP participants and controls. Quantitative susceptibility mapping (QSM) and inflow-based vascular-space occupancy MRI at 7T were performed on the two PSP participants and on two age-matched healthy controls to evaluate for differences in regional brain iron content and arteriolar cerebral blood volume (CBVa), respectively. Results: In the participant with PSP-ALS, the precentral gyrus demonstrated the highest [18F]-flortaucipir uptake of all brain regions relative to controls (z-score 1.94). In the participant with PSP-RS, [18F]-flortaucipir uptake relative to controls was highest in subcortical regions, including the pallidum, thalamus, hippocampus, and brainstem (z-scores 1.08, 1.41, 1.49, 1.32, respectively). Susceptibility values as a measure of brain iron content were higher in the globus pallidus and substantia nigra than in the midbrain and pons in each participant, regardless of group. CBVa values tended to be higher in the subcortical gray matter in PSP participants than in controls, although large measurement variability was noted in controls across multiple regions. Conclusion: In vivo tau PET imaging of an individual with PSP-ALS overlap demonstrated increased tau burden in the motor cortex that was not observed in PSP-RS or control participants. Consistent with prior PET studies, tau burden in PSP-RS was mainly observed in subcortical regions, including the brainstem and basal ganglia. QSM data suggest that off-target binding to iron may account for some but not all of the increased [18F]-flortaucipir uptake in the basal ganglia in PSP-RS. These findings support existing evidence that tau PET imaging can distinguish among PSP subtypes by detecting distinct regional patterns of tau deposition in the brain. Larger studies are needed to determine whether CBVa is sensitive to changes in brain microvasculature in PSP.

Effect of nitric oxide modulators on cerebrospinal fluid outflow through the cribriform plate of C57Bl/6 mice

Introduction. Beside the excretion of metabolic wastes, the lymphatic system in CNS play a crucial role in the regulation of intracranial pressure that is vital for the organism. One of the possible pathways of cerebrospinal fluid (CSF) drainage is its flow through the foramen of the cribriform plate (CP) into the nasal cavity. Despite the significant contribution of the nasal tract to the overall dynamics of the liquor, not much is known about the mechanisms of this process and how it is regulated. Due to its influence on the tone of blood vessels and peristalsis of lymphatic vessels, nitric oxide (NO) is a powerful modulator of liquor outflow, but its effects on nasal CSF outflow have not been studied yet. Aim and Methods. Using diffusion-weighted magnetic resonance imaging (DW MRI), we characterized the changes in CSF outflow through the CP of C57Bl/6 mice influenced by intranasal application of NO synthesis modulators. Results. In our study, using DW MRI and computer tomography (CT) mapping of the CP, we detected significant CSF outflow through its large dorsal and ventral foramen located along the nasal septum. At the same time, the CSF flow rate through the dorsal orifices of the CP was the highest. In addition, we showed that intranasal introduction of NO donor after 30 min leads to a significant decrease of water diffusion through the CP whereas application of a nonspecific NO synthase inhibitor into the nasal cavity enhances nasal outflow. The effects of the NO modulators did not have any significant spatial patterns; CSF outflow was significantly altered across all CP orifices regardless of their size or localization. Conclusion. The obtained results demonstrate the potential possibility of noninvasive local regulation of liquor dynamics, which may be used in the development of new approaches to the therapy of intracranial hypertension of various etiologies and methods of CNS detoxification.

Role of intravoxel incoherent motion MRI in diagnosis and assessment of invasiveness of urothelial bladder carcinoma

BackgroundUrinary bladder cancer is a common malignancy. Preoperative accurate judgment of the degree of tissue invasion is crucial to determine the plan of therapy. We aimed in the current study to evaluate the role of intravoxel incoherent motion (IVIM) MRI and apparent diffusion coefficient (ADC) map in differentiating muscle invasive from non-muscle invasive carcinomas.ResultsValues of IVIM-derived true diffusion coefficient (D), pseudo-diffusion coefficient (D*) and perfusion fraction (F) and ADC were lower in muscle invasive carcinomas than non-invasive masses with p values < 0.001 and 0.001, respectively. In MIBC, ADC was (0.9 × 10−3 mm2/s), D was (0.8 × 10−3 mm2/s), D* was (6.9 × 10−3 mm2/s) and F was (16.9%). In NMIBC, ADC was (1 × 10−3 mm2/s), D was (1.1 × 10−3 mm2/s), D* was (10.2 × 10−3 mm2/s) and F was (17.7%). Mass D cut off values, sensitivity and specificity and AUC were < 0.9, 83.93, 96.30 and 0.945, respectively. Mass ADC cut off values, sensitivity and specificity and AUC were < 1.09, 87.50, 51.85 and 0.721, respectively. The degree of agreement between IVIM parameters and the pathological staging was assessed by Kappa test. The best agreement was detected for mass D (K = 0.796), while the mass ADC and wall beside mass D showed moderate and fair agreement (k = 0.418 and 0.325, respectively).ConclusionsIVIM MRI parameters and ADC map can be utilized to detect the degree of tissue invasion caused by bladder cancer.

Diffusion Kurtosis Imaging and Radiomics in Diffuse Axonal Injury

This study aimed to assess the feasibility of radiomic features derived from diffusion kurtosis imaging (DK MRI) in identifying microstructural brain damage in diffuse axonal injury (DAI) and predicting its outcome. We hypothesized that radiomic features, computed from parametric DK MRI maps, may differ between healthy individuals and those with trauma, and may be related to DAI outcomes. The study included 31 DAI patients and 12 healthy volunteers. A total of 342,300 radiomic features were calculated (2282 features for each combination of 10 parametric DK maps with 15 regions of interest). Our findings suggest that the set of radiomic features effectively distinguishes between healthy and damaged brain tissues, and can predict DAI outcome. A broad spectrum of radiomic parameters based on DK MRI data showed high diagnostic and prognostic potential in DAI, presenting advantages beyond the traditionally used average values for the regions of interest on parametric DK MRI maps.

Atypical case of glioblastoma localization: infratentorial localization (Clinical Case and the Review of the Literature)

Glioblastoma is the most common high-grade primary brain tumor, occurring primarily in adults. This infiltrating tumor locates deep in the white matter, subcortical structures and thalamus. The typical localization of glioblastoma is supratentorial, accounting for more than 99% of cases. Primary infratentorial growth of glioblastomas involving the cerebellum is a very rare condition, occurring in less than 1 % of cases reported in the literature. The differential diagnosis consists mainly of solitary metastatic lesions and medulloblastoma. The clinical manifestations of cerebellar lesions are similar, but the methods of surgical and chemoradiotherapy treatment, prognosis and outcome in cases with various histologic types of the tumors are different.Thus radiology, carried out using multiparametric MRI mapping, is an decision making procedure. In thus publication we present an atypical case of infratentorial glioblastoma in a 45-yearold patient.

T1 mapping combined with arterial spin labeling MRI to identify renal injury in patients with liver cirrhosis.

We investigated the capability and imaging criteria of T1 mapping and arterial spin labeling (ASL) MRI to identify renal injury in patients with liver cirrhosis. We recruited 27 patients with cirrhosis and normal renal function (cirrhosis-NR), 10 with cirrhosis and renal dysfunction (cirrhosis-RD) and 23 normal controls (NCs). All participants were examined via renal T1 mapping and ASL imaging. Renal blood flow (RBF) derived from ASL was measured from the renal cortex, and T1 values were measured from the renal parenchyma (cortex and medulla). MRI parameters were compared between groups. Diagnostic performances for detecting renal impairment were statistically analyzed. Cortical T1 (cT1) and medullary T1 (mT1) were significantly lower in the NCs than in the cirrhosis-NR group. The cortical RBF showed no significant changes between the NCs and cirrhosis-NR group but was markedly decreased in the cirrhosis-RD group. The areas under the curve (AUCs) for discriminating cirrhosis-NR from NCs were 0.883 and 0.826 by cT1 and mT1, respectively. Cortical RBF identified cirrhosis-RD with AUC of 0.978, and correlated with serum creatinine (r = -0.334) and the estimated glomerular filtration rate (r = 0.483). A classification and regression tree based on cortical RBF and cT1 achieved 85% accuracy in detecting renal impairment in the cirrhosis. Renal T1 values might be sensitive predictors of early renal impairment in patients with cirrhosis-NR. RBF enabled quantifying renal perfusion impairment in patients with cirrhosis-RD. The diagnostic algorithm based on cortical RBF and T1 values allowed detecting renal injury during cirrhosis.

McTFI QSM MRI ABC/2 intracranial hemorrhage to noncontrast head CT volume measurement equivalence

Background/objectivesIntracranial hemorrhage (ICH) volume assessment is an important part of patient management and is routinely obtained by non-contrast head CT (NCHCT) using the validated ABC/2 measurement method. Because conventional MRI imaging sequences demonstrate variability in ICH appearance, volumetric analyses for MRI bleed volume in a standardized manner using ABC/2 is not possible. The recently introduced multiecho-complex total field inversion quantitative susceptibility mapping (mcTFI QSM) MRI technique, which maps brain tissue susceptibility to both depict brain tissue structures and quantify tissue susceptibility, may provide a viable alternative. In this study we evaluated mcTFI QSM ABC/2 ICH volume assessment relative to NCHCT. MethodsPatients with ICH who had undergone NCHCT and MRI brain scans within 48 h were recruited for this retrospective study. The ABC/2 method was applied to estimate the bleed volume for both NCHCT and MRI by a CAQ-certified neuroradiologist with 10 years of experience and a trained laboratory assistant. Results were analyzed via Bland-Altman (B-A) and linear regression. Results54 patients (27 females) who had undergone NCHCT and MRI within 48 h (<24 h., n = 31, 24-48 h, n = 10) were enrolled. mcTFI QSM ICH volume measurement method showed a positive correlation (99.5%) compared to NCHCT. B-A plot comparing ABC/2 ICH volume on NCHCT and mcTFI MRI done for patients within 24 h demonstrates a bias of −0.09%. ConclusionsICH volume calculation using ABC/2 on mcTFI QSM showed a high correlation with NCHCT measurement. These results suggest mcTFI QSM is a promising MRI method for ABC/2 for bleed volume measurement.

MRI T2 mapping and quantitative ultrasound shear wave elastography in cartilage integrity assessment for juvenile idiopathic arthritis patients

BackgroundJuvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in childhood that can lead to irreversible cartilage damage, with associated disability and decreased life quality. Shear wave elastography and quantitative MRI mapping can be used to identify early cartilage affection. PurposeTo evaluate diagnostic utility of distal femoral cartilage shear wave elastography and MRI T2 mapping in patients with symptomatic knee and investigate their potential clinical significance.Material and methodsTwenty patients with knee affection (study group) and 20 volunteers with the same demographic characteristics but without symptomatic knee pain (control group) were included in the study. A total of 80 knee joints of 40 individuals were evaluated. At the medial, intercondylar, and lateral condylar levels, distal femoral cartilage thickness was measured by B-mode ultrasonography and MRI, stiffness was assessed by shear wave elastography, and T2 relaxation time was measured by MRI.ResultsThe medial, intercondylar, and lateral cartilage thickness measurements were similar between the two groups and no statistically significant difference was observed while measured by US (P value 0.653,0.702,0.607) and MRI (P value 0.414, 0.4187, 0.3903). The shear wave velocity values in the study group were significantly higher than in the control group (P value 0.0202). There was a statistically significant difference between the average T2 relaxation time values for the distal femoral cartilage in the study and the control groups (P value 0.0027). SWE results were statistically significant in moderate and high disease activity while T2* revealed statistically significant p values in low as well as moderate and high disease activity; we found the best cutoff values for detection of cases using shear wave elastography velocity ratio (m/sec) about 4.445 with significant p value = 0.02, sensitivity 59.3% and specificity = 70.45%.ConclusionShear wave elastography and MRI T2 mapping are reliable, non-invasive, and acceptable methods for the assessment of pathologic cartilage. Better diagnostic information of hyaline cartilage can be obtained by adding up an extra sequence called T2 mapping to the routine MRI protocol of knee.

Abstract 18924: Structural and Electrical Remodeling Differences in Ischemia-Reperfusion versus Non-Reperfusion Myocardial Infarction

Background: Structural and electrical remodeling following myocardial infarction (MI) can result in the development of arrhythmogenic substrate and ventricular tachycardia (VT). Various clinical factors such as reperfusion status, and occluded coronary distribution can impact the size of post-infarction scar. Objective: To investigate the structural and electrical remodeling characteristics in 2 different porcine models of MI. Methods: Fourteen swine underwent anterior infarction via 180min balloon occlusion followed by reperfusion (IR Group, n=7) or chronic total occlusion by embolizing the mid-LAD with a coil (CTO Group, n=7). Cardiac MRI and electroanatomic substrate mapping (Thermocool ST-SF) and high-resolution activation mapping (Pentaray 2-6-2mm) was performed in all subjects 8-9 weeks following infarction. Low bipolar voltage area (&lt;1.5mV), very low bipolar voltage area (&lt;0.5mV), and CMR LGE intensity volume reconstruction (inHeart Medical) were assessed. Programmed stimulation from the Ventricular apex was performed for VT inducibility assessment. Results: The CTO group had more extensive low bipolar voltage area (CTO: 36±6cm 2 vs. IR: 23±12cm 2 , p=0.04) and dense low bipolar voltage areas (CTO: 20±7cm 2 vs. IR: 7±6cm 2 , p=0.01). LV EDV was similar (CTO: 122±14ml vs. IR: 136±38ml, np) and there was no significant difference in LVEF (CTO: 28±4% vs. IR: 26±4%, np) and CMR LGE scar volume (CTO: 12±3ml vs. IR: 12±4ml, np). Voltage mapping demonstrated clear significant differences in substrate size and LV Endocardial CMR LGE intensity was more homogeneous in the CTO group than the IR group (Figure). Monomorphic VT was inducible in all 14 subjects. A total of 19 VTs were induced in CTO group (range 1-4, TCL 241±33ms) and 12 in IR group (range 1-2, TCL 208±17ms). Conclusions: Creation of a chronic infarct results in a significantly larger area of abnormal arrhythmogenic substrate than 180 minutes of ischemia-reperfusion.

63 A Literature Review of Cortical Mapping, fMRI, and Standards of Care in Pediatric Epilepsy Surgical Workup

Objective:Epilepsy includes recurrent, unprovoked seizures and affects 470,000 children in the US, of which 7% have drug-resistant epilepsy due to failing two or more antiseizure medication trials. For some patients with drug-resistant epilepsy, surgery has been successful in reducing seizure burden. Functional MRI (fMRI) and intracranial mapping of neurocognitive functions, especially language, are increasingly done to assess potential functional loss from epilepsy surgery. However, these procedures vary by medical institute. The purpose of this review was to examine published literature on fMRI and intracranial mapping procedures for pediatric epilepsy surgery workup toward development of a standardized protocol that can be used across institutes as a guide to standard-of-care best practices for predicting loss of function associated with epilepsy surgery.Participants and Methods:Our literature review includes information from 8 electronic databases for peer-reviewed, English language studies of evaluation for pediatric epilepsy surgery candidacy. Thirty-one studies were selected based on inclusion criteria. Only studies including fMRI and intracranial mapping conducted with pediatric patients being worked up for epilepsy surgery were selected.Results:Our review revealed that the most common task used in fMRI and intracranial mapping procedures is visual-object naming, but type of naming tasks and the way they are administered varies widely across medical institutes and includes published measures and those created on site. Variability makes examining findings across studies and designing best practice for these procedures challenging.Conclusions:Creating gold-standard procedures for fMRI and intracranial mapping administration for epilepsy surgery evaluations is critical in optimizing treatment and functional outcomes for our pediatric patients. Our review is an initial step in this process.

Parametric Response Mapping of Co-Registered Ivim MRI and PET to Identify Radioresistant Sub-Volumes in Locally Advanced Cervical Carcinoma Undergoing CCRT

To investigate parametric response mapping (PRM) of co-registered positron emission tomography (PET) and intravoxel incoherent motion (IVIM) MRI in locally advanced cervical carcinoma patients to identify sub-volumes that may predict treatment response to adjuvant concurrent chemoradiation therapy (CCRT). Pre- and on-treatment (∼after four weeks of CCRT) diffusion weighted images (DWIs) MRI and pre-treatment PET were performed on 20 cervical cancer patients (median [range] age: 63 [41 to 85]; FIGO staging: 3 IIB, 1 IIIB, 10 IIIC1, 4 IIIC2, 2 IVA; histology: 11 squamous cell carcinoma, 4 endocervical adenocarcinoma; LN status: 4 negative, 16 positive). IVIM MRI maps were generated by Bayesian fitting of a two-compartment IVIM model to the DWIs to produce three-dimensional diffusion coefficient (D) and perfusion fraction (f). Three-dimensional IVIM D and f maps were co-registered to PET standardized uptake value (SUV) maps. Population means of PET SUV, IVIM D and f from pre-treatment scans were calculated to generate thresholds to identify low versus high metabolic (μSUV) regions, low versus high diffused (μD) regions as well as low versus high perfused (μf) regions, respectively. PRM maps were generated using voxel-wise joint histogram analysis to classify voxels within the tumor as highly metabolic and with low cellular density (SUV↑D↑), highly metabolic and with high cellular density (SUV↑D↓), metabolically inactive and with high cellular density (SUV↓D↓), or metabolically inactive and with low cellular density (SUV↓D↑) tissue based on the population mean thresholds. Similar PRM maps were generated using the joint histogram analysis with SUV and f. Summary statistics for these and other imaging parameters were calculated pre- and on-treatment. Univariate analysis was performed to determine relationships between relative change in gross tumor volume (ΔGTV) and pre-treatment imaging measurements. In tumors, on- versus pre-treatment tumor volume (p<.001) significantly decreased, while IVIM f (p = .002) and D (p = .03) significantly increased. Pre-treatment tumor volume (r = .45, p = .04) and PRM SUV↑D↓ (r = .65, p = .002) regions were positively related with ΔGTV, while pre-treatment IVIM D (r = -.64, p = .002), PRM SUV↓f↑ (r = -.52, p = .02) and PRM SUV↓D↑ (r = -.74, p<.001) regions were negatively related with ΔGTV. The latter PRM result suggests that larger regions of low cellular density (as represented by elevated D) + low metabolism result in a reduced change in tumor volume on-treatment, potentially representing a radioresistant sub-volume. PRM, generated from PET and IVIM MRI, was applied to patients with locally advanced cervical carcinoma and radioresistant sub-volumes were identified which may predict treatment response. The complementary information provided from PET and IVIM, combined using PRM, may assist in decision-making to individualize therapies, such as with image guided brachytherapy, to improve patient outcomes.

Evaluation of finger cartilage composition in recreational climbers with 7Tesla T2 mapping magnetic resonance imaging.

Sport climbing may lead to tissue adaptation including finger cartilage before apparent surface damage is detectable. The main aim was to assess finger cartilage composition with T2 mapping in young, active climbers and to compare the results to a non-climbers' collective. A secondary aim was to compare whether differences in cartilage T2 times are observed between older vs. younger volunteers. 7 Tesla MRI of the fingers Dig.2-4 was performed using a multi-echo spin echo sequence. Manual segmentation of 3 ROIs at the metacarpal heads, 1 ROI at the base phalanx and 1 ROI at the proximal interphalangeal joint was performed. Included were 13 volunteers without history of trauma who are regularly performing climbing activities as a recreational sport (>20 h/month). These were age-matched with 10 control subjects not performing climbing activities. Mean age was 32.4 years for the climbing group and 25.8 years for the controls. Mean T2 values for the 5 different ROIs were 42.2 ± 7.8 msec for climbers and 41.4 ± 6.8 msec for non-climbers. No significant differences were observed for T2 values between both groups. However, higher age had a significant impact on T2 values for all assessed ROIs (higher age 44.2 ± 9.5, younger age 32.9 ± 5.7, p = 0.001). This study evaluated the cartilage composition of young, engaged climbers with a T2 mapping MRI technique with the purpose to depict early onset joint changes. No negative impact on cartilage composition due to the sport activity was found, whereas age-related effects on the cartilage seemed to be more prominent.

Prostate MR image quality of apparent diffusion coefficient maps versus fractional intracellular volume maps from VERDICT MRI using the PI-QUAL score and a dedicated Likert scale for artefacts

PurposeThis study aimed to assess the image quality of apparent diffusion coefficient (ADC) maps derived from conventional diffusion-weighted MRI and fractional intracellular volume maps (FIC) from VERDICT MRI (Vascular, Extracellular, Restricted Diffusion for Cytometry in Tumours) in patients from the INNOVATE trial. The inter-reader agreement was also assessed. MethodsTwo readers analysed both ADC and FIC maps from 57 patients enrolled in the INNOVATE prospective trial. Image quality was assessed using the Prostate Imaging Quality (PI-QUAL) score and a subjective image quality Likert score (Likert-IQ). The image quality of FIC and ADC were compared using a Wilcoxon Signed Ranks test. The inter-reader agreement was assessed with Cohen’s kappa. ResultsThere was no statistically significant difference between the PI-QUAL score for FIC datasets compared to ADC datasets for either reader (p = 0.240 and p = 0.614). Using the Likert-IQ score, FIC image quality was higher compared to ADC (p = 0.021) as assessed by reader-1 but not for reader-2 (p = 0.663). The inter-reader agreement was ‘fair’ for PI-QUAL scoring of datasets with FIC maps at 0.27 (95% confidence interval; 0.08–0.46) and ADC datasets at 0.39 (95% confidence interval 0.22–0.57). For Likert scoring, the inter-reader agreement was also ‘fair’ for FIC maps at 0.38 (95% confidence interval; 0.10–0.65) and substantial for ADC maps at 0.62 (95% confidence interval; 0.39–0.86). ConclusionImage quality was comparable for FIC and ADC. The inter-reader agreement was similar when using PIQUAL for both FIC and ADC datasets but higher for ADC maps compared to FIC maps using the image quality Likert score.

OP17_9. Evaluation of placental oxygenation and perfusion in a rat model of placental dysfunction using quantitative T2* mapping and 3D-DCE MRI

OP17_9. Evaluation of placental oxygenation and perfusion in a rat model of placental dysfunction using quantitative T2* mapping and 3D-DCE MRI

Optimizing fibrosis detection: a comparison of electroanatomical mapping and late enhancement gadolinium magnetic resonance imaging.

Fibrotic atrial cardiomyopathy plays an important role in determining the outcome of ablation in patients with atrial fibrillation (AF). Two main methods are being used for the evaluation of fibrosis: voltage-based high-density (HD) electroanatomical mapping (EAM) and late gadolinium enhancement MRI (LGE-MRI). The comparability between both methods in detecting fibrosis has not been systematically investigated. LGE-MRIs of the left atrium (LA) were performed in 21 patients. LA-fibrosis was evaluated using a custom-designed software generating a 3D-model of the LA. HD-electroanatomical maps were recorded in each patient. After processing the maps and the MRI models by excluding the mitral valve, pulmonary veins, and the left atrial appendage, the LGE areas were measured and compared to the low voltage areas (LVA) in the HD maps using three different cutoff values of 0.5 mV, 0.7 mV, and 1.0 mV. The analysis revealed significant differences between EAM and LGE-MRI in assessing LA-fibrosis at 0.5-mV (for anterior and posterior walls) and 1.0-mV cutoffs (for anterior and posterior wall and septum). However, no significant differences were found between EAM and LGE-MRI when using a 0.7-mV cutoff for all the investigated areas. A voltage cutoff of 0.7 mV provided the best correlation between EAM and LGE MRI for detecting left atrial fibrosis. It supports the idea that a 0.5-mV cutoff may underestimate fibrosis, as areas with local signal voltages between 0.6 and 0.8 mV could also show LGE on MRI. Further research is needed to determine the ideal voltage cutoff for detecting left atrial fibrosis.

Genetic topography and cortical cell loss in Huntington's disease link development and neurodegeneration.

Cortical cell loss is a core feature of Huntington's disease (HD), beginning many years before clinical motor diagnosis, during the premanifest stage. However, it is unclear how genetic topography relates to cortical cell loss. Here, we explore the biological processes and cell types underlying this relationship and validate these using cell-specific post-mortem data. Eighty premanifest participants on average 15 years from disease onset and 71 controls were included. Using volumetric and diffusion MRI we extracted HD-specific whole brain maps where lower grey matter volume and higher grey matter mean diffusivity, relative to controls, were used as proxies of cortical cell loss. These maps were combined with gene expression data from the Allen Human Brain Atlas (AHBA) to investigate the biological processes relating genetic topography and cortical cell loss. Cortical cell loss was positively correlated with the expression of developmental genes (i.e. higher expression correlated with greater atrophy and increased diffusivity) and negatively correlated with the expression of synaptic and metabolic genes that have been implicated in neurodegeneration. These findings were consistent for diffusion MRI and volumetric HD-specific brain maps. As wild-type huntingtin is known to play a role in neurodevelopment, we explored the association between wild-type huntingtin (HTT) expression and developmental gene expression across the AHBA. Co-expression network analyses in 134 human brains free of neurodegenerative disorders were also performed. HTT expression was correlated with the expression of genes involved in neurodevelopment while co-expression network analyses also revealed that HTT expression was associated with developmental biological processes. Expression weighted cell-type enrichment (EWCE) analyses were used to explore which specific cell types were associated with HD cortical cell loss and these associations were validated using cell specific single nucleus RNAseq (snRNAseq) data from post-mortem HD brains. The developmental transcriptomic profile of cortical cell loss in preHD was enriched in astrocytes and endothelial cells, while the neurodegenerative transcriptomic profile was enriched for neuronal and microglial cells. Astrocyte-specific genes differentially expressed in HD post-mortem brains relative to controls using snRNAseq were enriched in the developmental transcriptomic profile, while neuronal and microglial-specific genes were enriched in the neurodegenerative transcriptomic profile. Our findings suggest that cortical cell loss in preHD may arise from dual pathological processes, emerging as a consequence of neurodevelopmental changes, at the beginning of life, followed by neurodegeneration in adulthood, targeting areas with reduced expression of synaptic and metabolic genes. These events result in age-related cell death across multiple brain cell types.

Alternating Look-Locker for quantitative T1 , T1ρ and B1 3D MRI mapping.

To develop a new MRI method, entitled alternating Look-Locker (aLL), for quantitative , , and 3D mapping. A Look-Locker scheme that alternates magnetization from +Z and -Z axes of the laboratory frame is utilized in combination with a 3D Multi-Band Sweep Imaging with Fourier Transformation (MB-SWIFT) readout. The analytical solution describing the spin evolution during aLL, as well as the correction required for segmented acquisition were derived. The simultaneous and mapping are demonstrated on an agar/saline phantom and on an in-vivo rat head. relaxation was achieved by cyclically applying magnetization preparation (MP) modules consisting of two adiabatic pulses. values in the rat brain in-vivo and in a gadobenate dimeglumine (Gd-DTPA) phantom were compared to those obtained with a previously introduced steady-state (SS) method. The accuracy and precision of the analytical solution was tested by Bloch simulations. With the application of MP modules, the aLL method provides simultaneous and maps. Conversely, without it, the method can be used for simultaneous and mapping. values were similar with both aLL and SS techniques. However, the aLL method resulted in more robust quantitative mapping compared to the SS method. Unlike the SS method, the aLL method does not require additional scans for generating maps. The proposed method offers a new flexible tool for quantitative mapping of , , and . The aLL method can also be used with readout schemes different from MB-SWIFT.