Model-based representational similarity analysis of blood-oxygen-level-dependent fMRI captures threat learning in social interactions

Past research has shown that attributions of intentions to other's actions determine how we experience these actions and their consequences. Yet, it is unknown how such attributions affect our learning and memory. Addressing this question, we combined neuroimaging with an interactive threat learning paradigm in which two interaction partners (confederates) made choices that had either threatening (shock) or safe (no shock) consequences for the participants. Importantly, participants were led to believe that one partner intentionally caused the delivery of shock, whereas the other did not (i.e. unintentional partner). Following intentional versus unintentional shocks, participants reported an inflated number of shocks and a greater increase in anger and vengeance. We applied a model-based representational similarity analysis to blood-oxygen-level-dependent (BOLD)-MRI patterns during learning. Surprisingly, we did not find any effects of intentionality. The threat value of actions, however, was represented as a trial-by-trial increase in representational similarity in the insula and the inferior frontal gyrus. Our findings illustrate how neural pattern formation can be used to study a complex interaction.

Noninvasive assessment of kidney dysfunction in children by using blood oxygenation level-dependent MRI and intravoxel incoherent motion diffusion-weighted imaging

Objectives To explore whether multiparametric approach including blood oxygenation level-dependent MRI (BOLD-MRI) and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) can be applied in the assessment of renal function in children with chronic kidney disease (CKD). Materials and methods This prospective study included 74 children (CKD stage 1–3, 51; CKD stage 4–5, 12; healthy volunteers, 11) for renal MRI examinations including coronal T2WI, axial T1WI and T2WI, BOLD-MRI, and DWI sequences. We measured the renal cortex and medulla T2*, ADC, Dt, Dp, and fp values on BOLD and DWI images. Appropriate statistical methods were applied for comparing MRI-derived parameters among the three groups and calculating the correlation coefficients between MRI-derived parameters and clinical data. Receiver operating characteristic (ROC) curves were used to assess the diagnostic performance of MRI-derived parameters. Results There were significant differences in cortex T2*, ADC, Dt, fp and medulla T2*, ADC, Dt among the three groups. Cortex T2*, ADC, Dt, fp and medulla T2*, ADC, Dt had a trend: CKD stage 4–5 < CKD stage 1–3 < healthy volunteers. Cortex and medulla T2*, ADC, Dt were significantly correlated with eGFR, serum creatinine (Scr), cystatin C. In addition, cortex T2* and eGFR showed the highest correlation coefficient (r = 0.824, p < 0.001). Cortex Dt and medulla T2* were optimal parameters for differentiating healthy volunteers and CKD stage 1–3 or CKD stage 4–5 and CKD stage 1–3, respectively. Conclusions BOLD-MRI and IVIM-DWI might be used as a feasible method for noninvasive assessment of renal function in children with CKD.

A Reperfusion BOLD-MRI Tissue Perfusion Protocol Reliably Differentiate Patients with Peripheral Arterial Occlusive Disease from Healthy Controls

There is no established technique that directly quantifies lower limb tissue perfusion. Blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) is an MRI technique that can determine skeletal muscle perfusion. BOLD-MRI relies on magnetic differences of oxygenated and deoxygenated hemoglobin, and regional changes in oxy/deoxyhemoglobin ratio can be recorded by T2* weighted MRI sequences. We aimed to test whether BOLD-MRI can differentiate lower limb tissue perfusion in peripheral arterial occlusive disease (PAOD) patients and healthy controls. Twenty-two PAOD patients and ten healthy elderly volunteers underwent lower limb BOLD-MRI. Reactive hyperemia was provoked by transient cuff compression and images of the gastrocnemius and soleus muscles were continuously acquired at rest, during ischemia and reperfusion. Key BOLD parameters were baseline T2* absolute value and time to T2* peak value after cuff deflation (TTP). Correlations between imaging parameters and ankle-brachial index (ABI) was investigated. The mean TTP was considerably prolonged in PAOD patients compared to healthy controls (m. gastrocnemius: 111 ± 46 versus 48 ± 22 s, p = 0.000253; m. soleus: 100 ± 42 versus 41 ± 30 s, p = 0.000216). Both gastrocnemius and soleus TTP values correlated strongly with ABI (−0.82 and −0.78, p < 0.01). BOLD-MRI during reactive hyperemia differentiated most PAOD patients from healthy controls. TTP was the most decisive parameter and strongly correlated with the ABI.

Blood oxygenation level-dependent MRI at 3T for differentiating prostate cancer from benign tissue: a preliminary experience

Objective: Blood oxygenation-level dependent (BOLD) MRI may identify or quantify the regional distribution of hypoxia within a tumor. We aimed to evaluate the feasibility of BOLD MRI at 3 T in differentiating prostate cancer from benign tissue. Methods: A total of 145 patients with biopsy-proven prostate cancer underwent BOLD MRI at 3 T. BOLD MRI was performed using a multiple fast field echo sequence to acquire 12 T2*-weighted images. The R2* value (rate of relaxation, s−1) was measured in the index tumor, and benign peripheral (PZ) and transition zone (TZ), and the results were compared. The variability of R2* measurements was evaluated. Results: Tumor R2* values (25.95 s−1) were significantly different from the benign PZ (27.83 s−1) and benign TZ (21.66 s−1) (p < 0.001). For identifying the tumor, the area under the receiver operating characteristic of R2* was 0.606, with an optimal cut-off value of 22.8 s−1 resulting in 73.8% sensitivity and 52% specificity. In the Bland–Altman test, the mean differences in R2* values were 8.5% for tumors, 13.3% for benign PZ, and 6.8% for benign TZ. No associations between tumor R2* value and Gleason score, age, prostate volume, prostate-specific antigen, or tumor size. Conclusion: BOLD MRI at 3 T appears to be a feasible tool for differentiating between prostate cancer and benign tissue. However, further studies are required for a direct clinical application. Advances in knowledge: The R2* values are significantly different among prostate cancer, benign PZ, and benign TZ.

Evaluation of Renal Oxygenation and Hemodynamics in Patients with Chronic Kidney Disease by Blood Oxygenation Level-dependent Magnetic Resonance Imaging and Intrarenal Doppler Ultrasonography

<b><i>Introduction:</i></b> The basic pathophysiologic derangement of chronic kidney disease (CKD) begins with the loss of nephrons, leading to renal hemodynamic changes, eventually causing a reduced nephron count and renal hypoxia. The purpose of this study was to observe the renal oxygenation and renal hemodynamics of patients with CKD using blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) and intrarenal Doppler ultrasonography (IDU). <b><i>Methods:</i></b> The study enrolled 39 patients with stage 1–4 CKD and 19 healthy volunteers (HVs). Based on their estimated glomerular filtration rate (eGFR), CKD patients were divided into 2 subgroups: a mild renal impairment (MI) group and a moderate to severe renal impairment (MSI) group. We monitored the participants’ mean cortical T2* (COT2*) and mean medullary T2* (MET2*) values on BOLD-MRI, and measured the peak systolic velocities (PSVs), end-diastolic velocities (EDVs), renal resistive index (RI), and kidney length by IDU. We also recorded clinical indicators such as age, sex, body mass index (BMI), 24-h urinary protein (24-h Upr), serum creatinine (sCr), blood urea nitrogen (BUN), and eGFR. BOLD-MRI, IDU measurements, and the clinical indicators were compared in CKD patients and HVs by the analysis of variance and Kruskal-Wallis <i>H</i> test. Spearman’s correlation was used to assess the relationship between data from BOLD-MRI and IDU and clinical indicators. <b><i>Results:</i></b> The COT2* values were significantly higher than the MET2* values in the HV, MI, and MSI groups. COT2*, MET2*, EDV, PSV, and kidney length gradually decreased in the HV, MI, and MSI groups (all <i>p &#x3c;</i> 0.05), whereas RI and 24-h Upr gradually increased (both <i>p</i> &#x3c; 0.05). Spearman correlation analysis showed that COT2* and MET2* were significantly positively correlated with eGFR, PSV, EDV, and kidney length but were significantly negatively correlated with sCr, BUN, and 24-h Upr (all <i>p</i> &#x3c; 0.05). There was no correlation observed between the COT2* and MET2* and the RI and BMI values. <b><i>Conclusions:</i></b> Renal oxygenation and blood flow velocities were found declined as the CKD stage progressed. The BOLD-MRI and IDU techniques may have clinical value by measuring intrarenal oxygenation and renal blood perfusion to judge the severity of renal damage in patients with CKD.

Evaluation of Renal Tissue Oxygenation Using Blood Oxygen Level-Dependent Magnetic Resonance Imaging in Chronic Kidney Disease

<b><i>Background:</i></b> Blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) has been widely used to assess renal oxygenation changes in different kidney diseases in recent years. This study was designed to evaluate and compare renal tissue oxygenation using 2 BOLD-MRI analysis methods, namely, the regional and whole-kidney region of interest (ROI) selection methods. <b><i>Methods:</i></b> The study ended up with 10 healthy controls and 40 chronic kidney disease (CKD) patients without dialysis. Their renal BOLD-MRI data were analyzed using whole-kidney ROI selection method and compared with regional ROI selection method. <b><i>Results:</i></b> We found the cortical, medullary, and whole-kidney R2* values were significantly higher in CKD patients than those in controls. Compared with the regional ROI selection method, the whole-kidney ROI selection method yielded higher cortical R2* values in both controls and CKD patients. The whole-kidney R2* values of deteriorating renal function group were significantly higher than those in stable renal function group. <b><i>Conclusions:</i></b> Cortical and medullary oxygenation was decreased significantly in CKD patients compared with the healthy controls, particularly in the medulla. The whole-kidney R2* values were positively correlated with kidney function and inversely correlated with the estimated glomerular filtration rate and effective renal plasma flow. Whole-Kidney R2* value might effectively predict the progression of renal function in patients with CKD.

Assessing placental function across gestation: a multi-institutional study of BOLD-MRI for the prediction of adverse pregnancy outcomes

The placenta is a remarkable organ that coordinates and regulates maternal-fetal interactions during pregnancy to optimize fetal development. A host of obstetric complications are associated with placental dysfunction, and existing methods for evaluating in vivo placental function fail to reliably detect at-risk pregnancies prior to maternal or fetal morbidity. Although routinely used as a monitoring tool, the predictive power of ultrasound for identifying compromised pregnancies is poor. Recent preclinical studies performed in our laboratory, using blood oxygen-level dependent magnetic resonance imaging (BOLD-MRI) in the pregnant nonhuman primate (NHP), established a strong correlation between placental T2* values and maternal-fetal oxygen transport. Here we extend this work to a large, longitudinal, two-site study of quantitative in vivo T2* mapping in human pregnancies across 11 to 38 weeks of gestation to characterize the evolution of placental oxygenation in uncomplicated pregnancies and to elucidate the relationship between aberrant placental T2* and adverse obstetric outcomes attributable to placental dysfunction. This methodology has high discriminatory power and strong potential diagnostic utility.

Blood Oxygen Level-Dependent (BOLD) MRI in Glomerular Disease

Renal hypoxia has recently been implicated as a key contributor and indicator of various glomerular diseases. As such, monitoring changes in renal oxygenation in these disorders may provide an early diagnostic advantage that could prevent potential adverse outcomes. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) is an emerging noninvasive technique for assessing renal oxygenation in glomerular disease. Although BOLD MRI has produced promising initial results for the use in certain renal pathologies, the use of BOLD imaging in glomerular diseases, including primary and secondary nephrotic and nephritic syndromes, is relatively unexplored. Early BOLD studies on primary nephrotic syndrome, nephrotic syndrome secondary to diabetes mellitus, and nephritic syndrome secondary to systemic lupus erythematosus have shown promising results to support its future clinical utility. In this review, we outline the advancements made in understanding the use of BOLD MRI for the assessment, diagnosis, and screening of these pathologies.