Decrease In Apparent Diffusion Coefficient Research Articles

Cerebral Small Vessel Disease in Children and Adolescents with Type 1 Diabetes Presenting with Diabetic Ketoacidosis during COVID-19 Era

Abstract Aim Cerebrovascular insult (CVI) is a known and significant morbidity of diabetic ketoacidosis (DKA); yet, its prevalence is underestimated. Untreated cerebral hypoperfusion in DKA may lead to cerebral injury, arterial ischemic stroke, cerebral venous thrombosis, and hemorrhagic stroke. This study assesses the cerebral perfusion status among children and adolescents with DKA during and after the resolution of DKA. Methodology Forty children and adolescents with type 1 diabetes mellitus (T1DM) presenting with DKA were assessed for severity of DKA, diabetes-duration, insulin therapy, Rappaport coma/ Near coma scale, Rancho los amigos levels of cognitive functioning scale, glycated-hemoglobin (HbA1c), D-dimer, INR and brain magnetic resonance imaging (MRI) during DKA and repeated neuro cognitive scoring, laboratory and MRI after resolution of the DKA. Results The mean age of the children and adolescents with T1DM presenting with DKA was 11.40 ± 2.82 years; their median diabetes-duration was 3 year; their mean HbA1c was 13.54 ± 2%. There was significant increase in platelet (P = 0.005), D-dimer (P < 0.001), Creatinine (P < 0.001) and Pulse wave velocity (P = 0.004) during attack of DKA while there was significance decrease in Apparent diffusion coefficient (P < 0.001). There was 30% of children and adolescents with T1DM had ischemic MRI changes during DKA. In children and adolescent with ischemic changes there was significant increase in severity of DKA (P = 0.003), HbA1c (P = 0.016), INR (P = 0.002), D-dimer (P < 0.001), Creatinine (P = 0.003). Conclusion Significant cerebral hypoperfusion occur during the DKA which is correlated with the DKA severity and D-dimer levels.

Normal Brain and Brain Tumor ADC: Changes Resulting From Variation of Diffusion Time and/or Echo Time in Pulsed-Gradient Spin Echo Diffusion Imaging.

Increasing gradient performance on modern magnetic resonance imaging scanners has profoundly reduced the attainable diffusion and echo times for clinically available pulsed-gradient spin echo (PGSE) sequences. This study investigated how this may impact the measured apparent diffusion coefficient (ADC), which is considered an important diagnostic marker for differentiation between normal and abnormal brain tissue and for therapeutic follow-up. Diffusion time and echo time dependence of the ADC were evaluated on a high-performance 3 T magnetic resonance imaging scanner. Diffusion PGSE brain scans were performed in 10 healthy volunteers and in 10 brain tumor patients using diffusion times of 16, 40, and 70 ms, echo times of 60, 75, and 104 ms at 3 b-values (0, 100, and 1000 s/mm 2 ), and a maximum gradient amplitude of 68 mT/m. A low gradient performance system was also emulated by reducing the diffusion encoding gradient amplitude to 19 mT/m. In healthy subjects, the ADC was measured in 6 deep gray matter regions and in 6 white matter regions. In patients, the ADC was measured in the solid part of the tumor. With increasing diffusion time, a small but significant ADC increase of up to 2.5% was observed for 6 aggregate deep gray matter structures. With increasing echo time or reduced gradient performance, a small but significant ADC decrease of up to 2.6% was observed for 6 aggregate white matter structures. In tumors, diffusion time-related ADC changes were inconsistent without clear trend. For tumors with diffusivity above 1.0 μm 2 /ms, with prolonged echo time, there was a pronounced ADC increase of up to 12%. Meanwhile, for tumors with diffusivity at or below 1.0 μm 2 /ms, no change or a reduction was observed. Similar results were observed for gradient performance reduction, with an increase of up to 21%. The coefficient of variation determined in repeat experiments was 2.4%. For PGSE and the explored parameter range, normal tissue ADC changes seem negligible. Meanwhile, observed tumor ADC changes can be relevant if ADC is used as a quantitative biomarker and not merely assessed by visual inspection. This highlights the importance of reporting all pertinent timing parameters in ADC studies and of considering these effects when building scan protocols for use in multicenter investigations.

Quantitative Assessment of Intervertebral Disc Composition by MRI: Sensitivity to Diurnal Variation.

Whether diurnal variation exists in quantitative MRI indices such as the T1rho relaxation time (T1ρ) of the intervertebral disc (IVD) is yet to be explored. This prospective study aimed to evaluate the diurnal variation in T1ρ, apparent diffusion coefficient (ADC), and electrical conductivity (σ) of lumbar IVD and its relationship with other MRI or clinical indices. Lumbar spine MRI, including T1ρ imaging, diffusion-weighted imaging (DWI), and electric properties tomography (EPT), was conducted on 17 sedentary workers twice (morning and evening) on the same day. The T1ρ, ADC, and σ of IVD were compared between the time points. Their diurnal variation, if any, was tested for correlation with age, body mass index (BMI), IVD level, Pfirrmann grade, scan interval, and diurnal variation in IVD height index. The results showed a significant decrease in T1ρ and ADC and a significant increase in the σ of IVD in the evening. T1ρ variation had a weak correlation with age and scan interval, and ADC variation with scan interval. Diurnal variation exists for the T1ρ, ADC, and σ of lumbar IVD, which should be accounted for in image interpretation. This variation is thought to be due to diurnal variations in intradiscal water, proteoglycan, and sodium ion concentration.

773 Diffusion-Weighted MRI Tractography of Midline Thalamic Subnuclei Characterizes the Return of Consciousness Following Severe Traumatic Brain Injury

INTRODUCTION: The prefrontal projections of the mediodorsal (MD) and central lateral (CL) thalamus have been implicated in the recovery of consciousness following severe traumatic brain injury (sTBI), but their specific roles are unknown. The CL has been proposed to modulate levels of arousal, while the MD modulates attention. METHODS: We generated tractograms in 25 patients with sTBI using DSI-Studio. The CL and MD were seeds and the orbitofrontal (OFC), dorsolateral prefrontal (dlPFC), medial prefrontal (mPFC), and anterior cingulate (ACC) cortices were targets. Fractional anisotropy (FA), a measure of tract integrity, and apparent diffusion coefficient (ADC), a proxy for neuronal injury, were computed for each tract and compared between the early (within 30 days post-injury) and late/no command followers. Spearman correlations were calculated between tract FA and ADC and final Glasgow Coma Scale (GCS) scores. RESULTS: Tractography revealed significantly increased MD-OFC tract FA in early compared late/no command followers (P = 0.0125). There was a statistically significant decrease in ADC in early compared late/no command followers in CL-dlPFC (P = 0.0281) and MD-dlPFC (P = 0.0454) tracts. GCS scores were significantly correlated with CL-ACC (P = 0.018) and CL-dlPFC (P = 0.0061) FA, and were not found to be significant in all MD tracts. CONCLUSIONS: The FA and ADC differences between early and late/no responders implicate tract integrity of the MD-OFC and dlPFC as key mediators in the return of command-following after TBI, respectively. The CL-ACC and CL-dlPFC tract FA were found to be associated with an increased final GCS score, which grades verbal, eye opening and motor responses. Our results corroborate the MD’s involvement in the content of consciousness, distinct from the CL’s in mediating the ascending arousal network.

Porcine Model of the Growing Spinal Cord—Changes in Diffusion Tensor Imaging Parameters

Diffusion tensor imaging (DTI) is an advanced magnetic resonance imaging (MRI) technique that has promising applications for the objective assessment of the microstructure of the spinal cord. This study aimed to verify the parameters obtained using DTI change during the growth process. We also wanted to identify if the DTI values change on the course of the spinal cord. The model organism was a healthy growing porcine spinal cord (19 pigs, Polish White, weight 24-120 kg, mean 48 kg, median 48 kg, age 2.5-11 months, mean 5 months, median 5.5 months). DTI parameters were measured in three weight groups: up to 29 kg (five pigs), 30-59 kg (six pigs), and from 60 kg up (eight pigs). DTI was performed with a 1.5 Tesla magnetic resonance scanner (Philips, Ingenia). Image post-processing was done using the Fiber Track package (Philips Ingenia workstation) by manually drawing the regions of interest (nine ROIs). The measurements were recorded for three sections: the cervical, thoracolumbar and lumbar segments of the spinal cord at the C4/C5, Th13/L1, and L4/L5 vertebrae levels. In each case, one segment was measured cranially and one caudally from the above-mentioned places. The values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were obtained for each ROIs and compared. It is shown that there is a correlation between age, weight gain, and change in FA and ADC parameters. Moreover, it is noted that, with increasing weight and age, the FA parameter increases and ADC decreases, whereas the FA and ADC measurement values did not significantly change between the three sections of the spinal cord. These findings could be useful in determining the reference values for the undamaged spinal cords of animals and growing humans.

Reduced field-of-view and multi-shot DWI acquisition techniques: Prospective evaluation of image quality and distortion reduction in prostate cancer imaging

ObjectivesTo prospectively compare image quality and apparent diffusion coefficient (ADC) quantification for reduced field-of-view (rFOV)- and multi-shot echo-planar imaging (msEPI)-based diffusion weighted imaging (DWI), using single-shot echo-planar-imaging (ssEPI) DWI as the reference. MethodsUnder IRB approval and after informed consent, msEPI, rFOV, and ssEPI DWI acquisitions were prospectively added to clinical prostate MRI exams at 3.0 T. Image distortion was quantitatively evaluated by root-mean-squared displacement (dr.m.s.). Histogram-based quantitative ADC parameters were compared in a sub-set of patients for proven sites of prostate cancer and matched non-cancerous prostate. Three radiologists also independently evaluated the DWI sequences for subjective image quality and distortion/artifact on a 5-point Likert scale. ResultsTwenty-five patients were included (15 with proven sites of cancer). Average dr.m.s. demonstrated a small but statistically significant reduction in distortion for both rFOV and msEPI relative to ssEPI. Quantitative ADC parameters for prostate tumors demonstrated no significant difference across the 3 DWI acquisitions and each acquisition demonstrated a statistically significant decrease in mean ADC for tumor compared to normal prostate. Qualitative reader assessment demonstrated favorable image quality for rFOV and msEPI, more notable for msEPI. ConclusionsrFOV and msEPI DWI techniques achieved reduction in image distortion, improvement in image quality, and maintained reproducible ADC quantification compared to the standard ssEPI.

Quantitative Analysis of Diffusion-Restricted Lesions in a Differential Diagnosis of Status Epilepticus and Acute Ischemic Stroke.

Background and PurposeDistinction between acute ischemic stroke (AIS) and status epilepticus (SE) on MRI can be challenging as restricted diffusion may occur in both conditions. In this study, we aimed to test a tool, which could help in differentiating AIS from SE when restricted diffusion was present on MRI.Materials and MethodsIn diffusion weighted imaging (DWI) with a b-value of 1,000 and apparent diffusion coefficient (ADC) maps, we compared the ratios of intensities of gray values of diffusion-restricted lesions to the healthy mirror side in patients with AIS and SE. Patients were recruited prospectively between February 2019 and October 2021. All patients underwent MRI and EEG within the first 48 h of symptom onset.ResultsWe identified 26 patients with SE and 164 patients with AIS. All patients had diffusion-restricted lesions with a hyperintensity in DWI and ADC signal decrease. Diffusion restriction was significantly more intense in patients with AIS as compared to patients with SE. The median ratios of intensities of gray values of diffusion-restricted lesions to the healthy mirror side for DWI were 1.42 (interquartile range [IQR] 1.32–1.47) in SE and 1.67 (IQR 1.49–1.90) in AIS (p < 0.001). ADC decrease was more significant in AIS as compared to SE with median ratios of 0.80 (IQR 0.72–0.89) vs. 0.61 (IQR 0.50–0.71), respectively (p < 0.001). A cutoff value for ratios of DWI signal was 1.495 with a sensitivity of 75% and a specificity of 85%. Values lower than 1.495 were more likely to be associated with SE and higher values were with AIS. A cutoff value for ADC ratios was 0.735 with a sensitivity of 73% and a specificity of 84%. Values lower than 0.735 were more likely to be associated with AIS and higher values were with SE.ConclusionDiffusion restriction and ADC decrease were significantly more intense in patients with AIS as compared to SE. Therefore, quantitative analysis of diffusion restriction may be a helpful tool for differentiating between AIS and SE when restricted diffusion is present on MRI.

Hemostatic Radiotherapy for Gastric Cancer: MRI as an Alternative to Endoscopy for Post-Treatment Evaluation.

Pretreatment diagnosis by diffusion-weighted magnetic resonance imaging (DW-MRI) is useful to determine the effect of chemotherapy for gastric cancer. Here, we investigated the relationship among DW-MRI, endoscopy, and tumor markers. Eight patients underwent hemostatic radiotherapy (RT) for gastric cancer in this prospective study from 2019 to 2021. The patients completed MRI, endoscopy, and blood tests before RT; MRI, endoscopy, and blood tests 1month after RT; and MRI and blood tests 3months after RT. Correlations between changes in apparent diffusion coefficient (ADC) derived from DW-MRI and the tumor marker carcinoembryonic antigen (CEA) were investigated. Univariate analysis of overall survival showed that sex and chemotherapy treatment were statistically significant factors. The CEA values before and 1month after RT decreased significantly. There was no statistical difference between the CEA value 1 and 3months after RT. The ADC value before and 1month after RT increased significantly but not between 1 and 3months after RT. Comparing the ratio of ADC before RT to 1 (or 3) month(s) after RT with that of CEA before RT to 1 (or 3) month(s) after RT, we found an inverse relationship between the two ratios. Therefore, changes in ADC and CEA are correlated. Additionally, 3months after RT, the decrease in ADC appeared earlier than the decrease in CEA. ADC may indicate a biological change earlier than CEA, and the ratios of ADC and CEA may be important factors. These aspects warrant further confirmation in a larger sample population.

Hyperoxia-Induced ΔR1: MRI Biomarker of Histological Infarction in Acute Cerebral Stroke

ObjectiveTo evaluate whether hyperoxia-induced ΔR1 (hyperO2ΔR1) can accurately identify histological infarction in an acute cerebral stroke model.Materials and MethodsIn 18 rats, MRI parameters, including hyperO2ΔR1, apparent diffusion coefficient (ADC), cerebral blood flow and volume, and 18F-fluorodeoxyglucose uptake on PET were measured 2.5, 4.5, and 6.5 hours after a 60-minutes occlusion of the right middle cerebral artery. Histological examination of the brain was performed immediately following the imaging studies. MRI and PET images were co-registered with digitized histological images. The ipsilateral hemisphere was divided into histological infarct (histological cell death), non-infarct ischemic (no cell death but ADC decrease), and non-ischemic (no cell death or ADC decrease) areas for comparisons of imaging parameters. The levels of hyperO2ΔR1 and ADC were measured voxel-wise from the infarct core to the non-ischemic region. The correlation between areas of hyperO2ΔR1-derived infarction and histological cell death was evaluated.ResultsHyperO2ΔR1 increased only in the infarct area (p ≤ 0.046) compared to the other areas. ADC decreased stepwise from non-ischemic to infarct areas (p = 0.002 at all time points). The other parameters did not show consistent differences among the three areas across the three time points. HyperO2ΔR1 sharply declined from the core to the border of the infarct areas, whereas there was no change within the non-infarct areas. A hyperO2ΔR1 value of 0.04 s-1 was considered the criterion to identify histological infarction. ADC increased gradually from the infarct core to the periphery, without a pronounced difference at the border between the infarct and non-infarct areas. Areas of hyperO2ΔR1 higher than 0.04 s-1 on MRI were strongly positively correlated with histological cell death (r = 0.862; p < 0.001).ConclusionHyperO2ΔR1 may be used as an accurate and early (2.5 hours after onset) indicator of histological infarction in acute stroke.

Evaluation of Radiographic Contrast-Induced Nephropathy by Functional Diffusion Weighted Imaging.

Contrast-induced nephropathy (CIN) resembles an important complication of radiographic contrast medium (XCM) displayed by a rise in creatinine levels 48–72 h after XCM administration. The purpose of the current study was to evaluate microstructural renal changes due to CIN in high-risk patients by diffusion weighted (DWI) and diffusion tensor imaging (DTI). Fifteen patients (five CIN and ten non-CIN) scheduled for cardiological intervention were included in the study. All patients were investigated pre- and post-intervention on a clinical 3T scanner. After anatomical imaging, renal DWI was performed by a paracoronal echo-planar-imaging sequence. Renal clinical routine serum parameters and advanced urinary injury markers were determined to monitor renal function. We observed a drop in cortical and medullar apparent diffusion coefficient (ADC) and fractional anisotropy (FA) before and after XCM administration in the CIN group. In contrast, the non-CIN group differed only in medullary ADC. The decrease of ADC and FA was apparent even before serum parameters of the kidney changed. In conclusion, DWI/DTI may be a useful tool for monitoring high-risk CIN patients as part of multi-modality based clinical protocol. Further studies, including advanced analysis of the diffusion signal, may improve the identification of patients at risk for CIN.

Whole brain in vivo neuropathology: Imaging site-specific changes in brain structure over time following trimethyltin exposure in rats

Presented is a diffusion weighted imaging protocol with measures of apparent diffusion coefficient which when registered to a 3D MRI rat brain atlas provides site-specific information on 173 different brain areas. This protocol coined “in vivo neuropathology” was used to follow the progressive neurotoxic effects of trimethyltin on global gray matter microarchitecture. Four rats were given an IP injection of 7 mg/kg of the neurotoxin trimethyltin and imaged for changes in water diffusivity at 3- and 7-days post injections. At 3 days, there was a significant decrease in apparent diffusion coefficient, a proxy for cytotoxic edema, in several cortical areas and cerebellum. At 7 days the level of injury expanded to include most of the cerebral cortex, hippocampus, olfactory system, and cerebellum/brainstem corroborating much of the work done with traditional histopathology. Analysis is achieved with a minimum number of rats adhering to the laws and regulations around the humane care and use of laboratory animals, providing an alternative to the traditional tests for assessing drug neurotoxicity. “In vivo neuropathology” can minimize the cost, expedite the process, and identify subtle changes in site-specific brain microarchitecture across the entire brain.

Brain Magnetic Resonance Imaging Reveals Different Courses of Disease in Pediatric and Adult Cerebral Malaria.

BackgroundCerebral malaria is a common presentation of severe Plasmodium falciparum infection and remains an important cause of death in the tropics. Key aspects of its pathogenesis are still incompletely understood, but severe brain swelling identified by magnetic resonance imaging (MRI) was associated with a fatal outcome in African children. In contrast, neuroimaging investigations failed to identify cerebral features associated with fatality in Asian adults. MethodsQuantitative MRI with brain volume assessment and apparent diffusion coefficient (ADC) histogram analyses were performed for the first time in 65 patients with cerebral malaria to compare disease signatures between children and adults from the same cohort, as well as between fatal and nonfatal cases. ResultsWe found an age-dependent decrease in brain swelling during acute cerebral malaria, and brain volumes did not differ between fatal and nonfatal cases across both age groups. In nonfatal disease, reversible, hypoxia-induced cytotoxic edema occurred predominantly in the white matter in children, and in the basal ganglia in adults. In fatal cases, quantitative ADC histogram analyses also demonstrated different end-stage patterns between adults and children: Severe hypoxia, evidenced by global ADC decrease and elevated plasma levels of lipocalin-2 and microRNA-150, was associated with a fatal outcome in adults. In fatal pediatric disease, our results corroborate an increase in brain volume, leading to augmented cerebral pressure, brainstem herniation, and death. ConclusionsOur findings suggest distinct pathogenic patterns in pediatric and adult cerebral malaria with a stronger cytotoxic component in adults, supporting the development of age-specific adjunct therapies.

DTI parameters in neonates with hypoxic-ischemic encephalopathy after total body hypothermia

Background and purpose MR imaging provides means for discriminating different patterns of Hypoxic-ischemic encephalopathy (HIE) and may distinguish most severe cases from less severe but is unable to predict long-term outcome. Diffusion tensor imaging (DTI) offers information for a more complete characterization of HIE. The purpose of this study is to compare the modifications of DTI parameters in newborns one week and six months following total-body cooling to healthy controls. Methods Forty-seven cooled newborns were studied with MRI, 20 underwent follow-up at 6 months. 12 healthy newborns and nine children at 6 months were enrolled as control groups (HC). Inferior Longitudinal Fasciculus (ILF), Corpus Callosum Fasciculus (CCF), Corticospinal Tract (CST), Optical Tract (OT), Optic Radiation (OR) were generated in all subjects. DTI parameters were evaluated in basal ganglia (BG), thalamus (TH) and tracks. Statistical analysis was performed with MANOVA. Results In newborns HIE versus HC, there were significantly lower fractional anisotropy (FA) on OR and CST and higher axial diffusivity (AD), apparent diffusion coefficient (ADC) and radial diffusivity (RD) values on CST, BG and TH in HIE-N. At 6 months there were no significant grouping effects. The analysis showed a significant increase of FA, decrease of ADC, AD, RD after 6 months for HIE and HC. Conclusions We observed modifications of parameter values in HIE newborns vs HC; however normalization of values at 6 months suggests that changes of parameters cannot be considered early biomarkers for evaluation of therapeutic hypothermia in newborns with moderate HIE and normal conventional MRI.

Diffusion tensor imaging reveals microstructural alteration of the trigeminal nerve root in classical trigeminal neuralgia without neurovascular compression and correlation with outcome after internal neurolysis

ObjectivesDiffusion tensor imaging (DTI) has been used to detect microstructural alteration and effect of surgical treatment of the trigeminal nerve root (TR) in patients with classical trigeminal neuralgia (CTN) underwent microvascular decompression (MVD). Patients with CTN without neurovascular compression (woNVC) is a special population of TN, however, the pathogenesy of CTN woNVC and the mechanism of internal neurolysis (IN) remain unknown. Materials and methods21 patients with CTN woNVC who underwent IN and 20 healthy controls were included in this study. The differences in the means, kurtosis and skewness of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) between the affected and unaffected nerves in patients and both nerves in controls were investigated by independent t-test and paired t-test respectively. Longitudinal changes of FA and ADC were correlated with outcome of IN via Spearman correlation coefficient. ResultsSignificant differences were found in preoperative mean and kurtosis values for both FA and ADC of the affected side TR, compared to the unaffected side and control group respectively. However, these differences remarkably reduced postoperatively. Further, the Spearman correlation coefficient showed a strong negative correlation between decrease of ADC in the affected side and the surgical outcome in BNI total score. ConclusionThe changes of diffusive property of TR, especially the FA and ADC, provide alternative radiological evidence for evaluating the mechanism of CTN woNVC. The modification of DTI metrics could be an effective factor for providing potential noninvasive biomarkers for determining the prognosis of patients with CTN woNVC underwent IN.

Chloride Diffusion in Concrete Protected with a Silane-Based Corrosion Inhibitor.

One of the most important parameters concerning durability is undoubtedly represented by cement matrix resistance to chloride diffusion in environments where reinforced concrete structures are exposed to the corrosion risk induced by marine environment or de-icing salts. This paper deals with protection from chloride ingress by a silane-based surface-applied corrosion inhibitor. Results indicated that the corrosion inhibitor (CI) allows to reduce the penetration of chloride significantly compared to untreated specimens, independently of w/c, cement type, and dosage. Reduction of chloride diffusion coefficient (Dnssn) measured by an accelerated test in treated concrete was in the range 30–60%. Natural chloride diffusion test values indicate a sharp decrease in apparent diffusion coefficient (Dapp) equal to about 75% when concrete is protected by CI. Mechanism of action of CI in slowing down the chloride penetration inside the cement matrix is basically due to the water repellent effect as confirmed by data of concrete bulk electrical resistivity.

Treatment-related changes in neuroendocrine tumors as assessed by textural features derived from 68Ga-DOTATOC PET/MRI with simultaneous acquisition of apparent diffusion coefficient

BackgroundNeuroendocrine tumors (NETs) frequently overexpress somatostatin receptors (SSTRs), which is the molecular basis for 68Ga-DOTATOC positron-emission tomography (PET) and radiopeptide therapy (PRRT). However, SSTR expression fluctuates and can be subject to treatment-related changes. The aim of this retrospective study was to assess, which changes in PET and apparent diffusion coefficient (ADC) occur for different treatments and if pre-therapeutic 68Ga-DOTATOC-PET/MRI was able to predict treatment response to PRRT.MethodsPatients with histopathologically confirmed NET, at least one liver metastasis > 1 cm and at least two 68Ga-DOTATOC-PET/MRI including ADC maps were eligible. 68Ga-DOTATOC-PET/MRI of up to 5 liver lesions per patients was subsequently analyzed. Extracted features comprise conventional PET parameters, such as maximum and mean standardized uptake value (SUVmax and SUVmean) and ADC values. Furthermore, textural features (TFs) from both modalities were extracted. In patients with multiple 68Ga-DOTATOC-PET/MRI a pair of 2 scans each was analyzed separately and the parameter changes between both scans calculated. The same image analysis was performed in patients with 68Ga-DOTATOC-PET/MRI before PRRT. Differences in PET and ADC maps parameters between PRRT-responders and non-responders were compared using Mann-Whitney test to test differences among groups for statistical significance.Results29 pairs of 68Ga-DOTATOC-PET/MRI scans of 18 patients were eligible for the assessment of treatment-related changes. In 12 cases patients were treated with somatostatin analogues between scans, in 9 cases with PRRT and in 2 cases each patients received local treatment, chemotherapy and sunitinib. Treatment responders showed a statistically significant decrease in lesion volume and a borderline significant decrease in entropy on ADC maps when compared to non-responders. Patients treated with standalone SSA showed a borderline significant decrease in mean and maximum ADC, compared to patients treated with PRRT. No parameters were able to predict treatment response to PRRT on pre-therapeutic 68Ga-DOTATOC-PET/MRI.ConclusionsPatients responding to current treatment showed a statistically significant decrease in lesion volume on ADC maps and a borderline significant decrease in entropy. No statistically significant changes in PET parameters were observed. No PET or ADC maps parameters predicted treatment response to PRRT. However, the sample size of this preliminary study is small and further research needed.

The diffusion-tensor imaging reveals alterations in water diffusion parameters in acute pediatric concussion.

Wide-spread visualization methods which are computed tomography (CT) and magnetic resonance imaging (MRI) are not sensitive to mild traumatic brain injury (mTBI). However, mTBI may cause changes of cerebral microstructure that could be found using diffusion-tensor imaging. The aim of this study is to reveal the impact of acute mTBI (no more than 3days after trauma) on diffusion parameters in corpus callosum, corticospinal tract, and thalamus in children (aged 14-18). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were analyzed. Significant increase in FA and decrease in ADC were observed in thalamus. The trend to an increase in FA is observed in corpus callosum.

Decreased frontal white-matter diffusion and improved cognitive flexibility after burr-hole surgery in moyamoya angiopathy

BackgroundIn Moyamoya Angioplasty (MMA), increased apparent diffusion coefficient (ADC) in frontal white matter (WM) with a normal appearance has been associated with frontal hypoperfusion and executive dysfunction. Multiple burr-hole surgery enables the revascularization of large frontal areas.Goal: To assess the effect of multiple burr-hole surgery on the ADC and cognitive functions in adults with MMA.MethodsADC was measured in 26 brain hemispheres of 14 consecutive adults with MMA (9 women, mean age ± SD: 38.1 ± 10.7 years) prior to and 6 months after burr-hole surgery. ADC was obtained from regions of interest located in frontal and posterior (temporo-occipital) normal-appearing WM. Ten patients had neuropsychological assessment that focused on executive and attentional functions before and after surgery.ResultsAnterior and posterior ADC values did not differ before surgery (815.8 ± 60.1 vs. 812.1 ± 35.3 mm2/s, p = 0.88). After surgery, frontal ADC was lower than prior to surgery (789.9 ± 64.5 vs. 815.8 ± 60.1 mm2/s; p <0.001) whereas no change occurred in posterior ADC (p = 0.31). Trail-making test part B median z-score increased from − 1.47 to − 0.21 (p = 0.018), suggesting improved cognitive flexibility.ConclusionIn adults with MMA, indirect revascularization with burr-hole is followed by a decrease of ADC in normal-appearing frontal WM and may have improved some executive functions in the flexibility process. Change in ADC may reflect the improvement in cerebral perfusion after surgery. The measuring of ADC may be a promising tool in exploring potentially reversible microstructural WM damage related to hypoperfusion and cognitive change in MMA.

Evaluation of Apparent Diffusion Coefficient as a Predictor of Grade Reclassification in Men on Active Surveillance for Prostate Cancer

To evaluate the association between apparent diffusion coefficient (ADC) on initial multiparametric MRI (mpMRI) and biopsy grade reclassification (GR) to grade group (GG) ≥2 prostate cancer (CaP) in men on active surveillance (AS) with GG 1 CaP. We retrospectively identified 242 AS patients with reported ADC values on their initial mpMRI. ADC value from the index lesion was assessed as an independent predictor of GR using a Cox model. To ease clinical interpretation, we used a log-rank test to establish an ADC cutoff of 1128×10-6 mm2/s for Kaplan-Meier analysis. Of the 242 men, 70 underwent GR following initial mpMRI, of which 26 (37%) had GR at the index lesion. There was no significant difference in the median interval between biopsies for men with and without GR (P >.9). Men with GR had significantly lower median ADC than those without GR (P=.01). In multivariable analysis adjusting for age, prostate-specific antigen density, and National Comprehensive Cancer Network risk group, a 100-unit decrease in ADC was associated with a 12% increase in the risk of GR (HR=1.12, 95% CI: 1.01-1.22, P=.03). Two- and 4-year rates of freedom from GR were significantly lower for men with ADC <1128×10-6 mm2/s vs ADC ≥1128×10-6 mm2/s (62% and 42% vs 78% and 68%, respectively; P <.001). For AS patients, lower ADC on initial mpMRI index lesion is associated with increased risk of GR to GG ≥2 CaP and would be a useful component of multivariable risk prediction tools.

Diffusion of tRNA inside the ribosome is position-dependent

In recent years, there has been a growing interest to quantify the energy landscape that governs ribosome dynamics. However, in order to quantitatively integrate theoretical predictions and experimental measurements, it is essential that one has a detailed understanding of the associated diffusive properties. Here, all-atom explicit-solvent simulations (50 μs of aggregate sampling) predict that the diffusion coefficient of a tRNA molecule will depend on its position within the ribosome. Specifically, during aa-tRNA accommodation (i.e., the process by which tRNA enters the ribosome), the apparent diffusion coefficient decreases by approximately an order of magnitude. By comparing these to values obtained with an energetically "smooth" model, we show that the observed nonuniform behavior likely arises from electrostatic and solvation interactions between the tRNA and ribosome. These calculations also reveal the hierarchical character of ribosomal energetics, where steric interactions induce a large-scale free-energy barrier, and short-scale roughness determines the rate of diffusive movement across the landscape.