Diffusion-weighted Imaging MRI Research Articles

Advanced MRI to differentiate schwannomas and metastases in the cerebellopontine angle/internal auditory canal.

Differentiating schwannomas and metastases in the cerebellopontine angles (CPA)/internal auditory canals (IAC) can be challenging. This study aimed to assess the role of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI (DCE-MRI) to differentiate schwannomas and metastases in the CPA/IAC. We retrospectively reviewed 368 patients who were diagnosed with schwannomas or metastases in the CPA/IAC between April 2017 and February 2022 in a single academic center. Forty-three patients had pretreatment DWI and DCE-MRI along with conventional MRI. Normalized mean apparent diffusion coefficient ratio (nADCmean) and DCE-MRI parameters of fractional plasma volume (Vp), flux rate constant (Kep), and forward volume transfer constant were compared along with patients' demographics and conventional imaging features between schwannomas and metastases as appropriate. The diagnostic performances and multivariate logistic regression analysis were performed using the significantly different values. Between 23 schwannomas (15 males; median 48 years) and 20 metastases (9males; median 61 years), nADCmean (median: 1.69 vs. 1.43; p = .002), Vp (median: 0.05 vs. 0.20; p<.001), and Kep (median: 0.41 vs. 0.81 minute-1 ; p<.001) were significantly different. The diagnostic performances of nADCmean, Vp, and Kep were 0.77, 0.90, and 0.83 area under the curves, with cutoff values of 1.68, 0.12, and 0.53, respectively. Vp was identified as the most significant parameter for the tumor differentiation in the multivariate logistic regression analysis (p<.001). DWI and DCE-MRI can help differentiate CPA/IAC schwannomas and metastases, and Vp is the most significant parameter.

Transradial versus transfemoral arterial approach for cerebral angiography and the frequency of embolic events on diffusion weighted MRI

BackgroundThe radial artery approach has become popular as a ‘radial first’ strategy for arterial access in neuroangiography and neurointerventions. Recent studies have shown that transradial arterial access (TRA) for cerebral...

Exploring the impact of metabolic imaging in head and neck cancer treatment.

BackgroundTarget volume delineation is performed with anatomical imaging for head and neck cancer. Molecular imaging allows the recognition of specific tumor regions. Its inclusion in the pathway could lead to changes in delineation and resultant treatment plans.MethodsPRISMA methodology was adhered to when selecting the articles for analysis and only full articles were quality assessed.ResultsSeventeen articles were included. Gross tumor volume (GTV) primary, GTV nodal, and other target volumes were evaluated. Positron emission tomography/computerized tomography (PET/CT) produced smaller primary GTVs, although not with diffusion‐weighted imaging‐magnetic resonance imaging (DWI‐MRI) or PET/MRI. The impact of these image modalities on GTV nodal did not display any consistency. Additionally, there was considerable heterogeneity in metrics comparing delineations. Four studies included appraised the dosimetric impact of the changes in target volume delineation.ConclusionQuantifying the impact of molecular imaging is difficult, due to heterogeneity in reporting metrics in molecular imaging modalities and a paucity of detail regarding delineation method and guideline adherence.

Investigated regional apparent diffusion coefficient values of the morphologically normal feline brain.

Diffusion-weighted imaging (DWI) MRI is increasingly available in veterinary medicine for investigation of the brain. However, apparent diffusion coefficient (ADC) values have only been reported in a small number of cats or in research settings. The aim of this study was to investigate the ADC values of different anatomical regions of the morphologically normal brain in a feline patient population. Additionally, we aimed to assess the possible influence on the ADC values of different patient-related factors, such as sex, body weight, age, imaging of the left and right side of the cerebral hemispheres and white vs grey matter regions. This retrospective study included cats undergoing an MRI (3T) examination with DWI sequences of the head at the Vetsuisse Faculty of the University Zurich between 2015 and 2021. Only cats with morphologically normal brains were included. On the ADC maps, 10 regions of interest (ROIs) were manually drawn on the following anatomical regions: caudate nucleus; internal capsule (two locations); piriform lobe; thalamus; hippocampus; cortex cerebri (two locations); cerebellar hemisphere; and one ROI in the centre of the cerebellar vermis. Except for the ROI at the cerebellar vermis, each ROI was drawn in the left and right hemisphere. The ADC values were calculated by the software and recorded. A total of 129 cats were included in this study. The ADC varied in the different ROIs, with the highest mean ADC value in the hippocampus and the lowest in the cerebellar hemisphere. ADC was significantly lower in the white cerebral matter compared with the grey matter. ADC values were not influenced by age, with the exception of the hippocampus and the cingulate gyrus. ADC values of different anatomical regions of the morphologically normal feline brain in a patient population of 129 cats in a clinical setting are reported for the first time.

Preliminary study of monoexponential, biexponential, and stretched-exponential models of diffusion-weighted MRI and diffusion kurtosis imaging on differential diagnosis of spinal metastases and chordoma.

Quantitative comparison of diffusion parameters from various models of diffusion-weighted (DWI) and diffusion kurtosis (DKI) imaging for distinguishing spinal metastases and chordomas. DWI and DKI examinations were performed in 31 and 13 cases of spinal metastases and chordomas, respectively. DWI derived apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo diffusion coefficient (D*), perfusion fraction (f), water molecular distributed diffusion coefficient (DDC), and intravoxel water diffusion heterogeneity (α). DKI derived mean diffusivity (MD) and mean kurtosis (MK). Independent sample t-testing compared statistical differences among parameters. Sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve were determined. Pearson correlation analysis evaluated the parameters' correlations. ADC, D, f, DDC, α, and MD were significantly lower in spinal metastases than chordomas (all P < 0.05). MK was significantly higher in spinal metastases than chordomas (P < 0.05). D had the highest area under the ROC curve (AUC) of 0.886, greater than MD (AUC = 0.706) or DDC (AUC = 0.742) in differentiating the two tumors (both P < 0.05). Combining D with f and α statistically significantly increased the AUC for diagnosis (to 0.995) relative to D alone (P < 0.05). There was a certain correlation among DDC, ADC, and D (all P < 0.05). Monoexponential, biexponential, and stretched-exponential models of DWI and DKI can potentially differentiate spinal metastases and chordomas. D combined with f and α performed best.

Early detection of ischemic brain injuries by diffusion-weighted imaging after radiofrequency ablation for fetal reduction in monochorionic pregnancies.

This study aimedto investigate the additional advantages of magnetic resonance imaging (MRI), particularly diffusion-weighted imaging (DWI) over fetal ultrasound in the detection of acute ischemic cerebral injuries in complicated monochorionic (MC) pregnancies that underwent selective reduction by radiofrequency ablation (RFA). This prospective cohort study was conducted on 40 women with complicated MC pregnancies who were treated by RFA. Fetal brain imaging by DWI and conventional MRI was performed either in the early (within 10 days after RFA) or late phase (after 3-6 weeks) in the surviving fetuses to detect both acute and chronic ischemic injuries. The presence of anemia after RFA was also evaluated by Doppler ultrasound. Overall, 13 of the total 43 fetuses (30.23%) demonstrated MRI abnormalities with normal brain ultrasound results including germinal matrix hemorrhage (GMH), extensive cerebral ischemia, and mild ventriculomegaly. Although seven fetuses with GMH eventually survived, fetuses that demonstrated ischemic lesions and ventriculomegaly on MRI died in the uterus. The absence of abnormal cerebral lesions or anemia on ultrasound and Doppler exams does not necessarily rule out fetal brain ischemia. Performing early MRI, particularly DWI seems to be a reasonable option for detection of early intracranial ischemic changes and better management of complicated multiple pregnancies which were treated by RFA.

MRI-Based Radiomics and Urine Creatinine for the Differentiation of Renal Angiomyolipoma With Minimal Fat From Renal Cell Carcinoma: A Preliminary Study

ObjectivesStandard magnetic resonance imaging (MRI) techniques are different to distinguish minimal fat angiomyolipoma (mf-AML) with minimal fat from renal cell carcinoma (RCC). Here we aimed to evaluate the diagnostic performance of MRI-based radiomics in the differentiation of fat-poor AMLs from other renal neoplasms.MethodsA total of 69 patients with solid renal tumors without macroscopic fat and with a pathologic diagnosis of RCC (n=50) or mf-AML (n=19) who underwent conventional MRI and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) were included. Clinical data including age, sex, tumor location, urine creatinine, and urea nitrogen were collected from medical records. The apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) were measured from renal tumors. We used the ITK-SNAP software to manually delineate the regions of interest on T2-weighted imaging (T2WI) and IVIM-DWI from the largest cross-sectional area of the tumor. We extracted 396 radiomics features by the Analysis Kit software for each MR sequence. The hand-crafted features were selected by using the Pearson correlation analysis and least absolute shrinkage and selection operator (LASSO). Diagnostic models were built by logistic regression analysis. Receiver operating characteristic curve analysis was performed using five-fold cross-validation and the mean area under the curve (AUC) values were calculated and compared between the models to obtain the optimal model for the differentiation of mf-AML and RCC. Decision curve analysis (DCA) was used to evaluate the clinical utility of the models.ResultsClinical model based on urine creatinine achieved an AUC of 0.802 (95%CI: 0.761-0.843). IVIM-based model based on f value achieved an AUC of 0.692 (95%CI: 0.627-0.757). T2WI-radiomics model achieved an AUC of 0.883 (95%CI: 0.852-0.914). IVIM-radiomics model achieved an AUC of 0.874 (95%CI: 0.841-0.907). Combined radiomics model achieved an AUC of 0.919 (95%CI: 0.894-0.944). Clinical-radiomics model yielded the best performance, with an AUC of 0.931 (95%CI: 0.907-0.955). The calibration curve and DCA confirmed that the clinical-radiomics model had a good consistency and clinical usefulness.ConclusionThe clinical-radiomics model may be served as a noninvasive diagnostic tool to differentiate mf-AML with RCC, which might facilitate the clinical decision-making process.

Endolymphatic sac tumour: exploring the role of CT and MRI features in the diagnosis of 22 cases

To explore the role of imaging features in the diagnosis of endolymphatic sac tumour (ELST). Twenty-two patients with ELST confirmed at histopathology were included in this retrospective study. All patients underwent computed tomography (CT) and magnetic resonance imaging (MRI) examinations, including diffusion-weighted imaging (DWI; n=18) and dynamic contrast-enhanced (DCE) MRI (n=3). The imaging features of this series were analysed. All lesions appeared as irregular soft-tissue mass lesions located in the middle and posterior margin of the petrous bone. At CT, the normal vestibular aqueduct structure disappeared. Multiple osteoid tissues were present inside the tumour, and destructive bone changes had a "honeycomb" pattern. Twenty cases were accompanied by the incomplete thin bony peripheral rim along the medial margin. On both T1-weighted imaging (WI) and T2WI, all lesions showed hyperintense, hypointense, and isointense mixed signal intensity. Scattered peripheral hyperintensities were found in all cases on T1WI. The mean apparent diffusion coefficient (ADC) value of 18 lesions was (1.35±0.13)×10-3 mm2/s, which was similar to that of masseter muscles. On enhanced T1WI, all lesions had significant heterogeneous enhancement, and the vascular flowing-void effect was seen in larger lesions (≥1.5 cm). The time-signal intensity curve (TIC) showed a plateau type in all three cases. The imaging features of ELST, including its location, bone destruction form, MRI signal intensity, and enhancement pattern, are helpful to improve the diagnostic accuracy of this rare tumour.

The "Black Straight-Line Sign" in the Putamen in Diffusion-Weighted Imaging: A Potential Diagnostic MRI Marker for Multiple System Atrophy.

Background and PurposeThe diagnosis of multiple system atrophy (MSA) remains challenging in clinical practice. This study investigated the value of hypointense signals in the putamen (“black straight-line sign”) in diffusion-weighted imaging (DWI) of brain MRI for distinguishing (MSA) from Parkinson's disease (PD).MethodsWe retrospectively enrolled 30 MSA patients, 30 PD patients, and 30 healthy controls who had undergone brain MRI between 2016 and 2020. Two readers independently assessed the signal intensity of the bilateral putamen on DWI. The putaminal hypointensity was scored using 4-point visual scales. Putaminal hypointensity and the presence of a “black straight-line sign” were statistically compared between MSA and PD or healthy controls.ResultsThe mean scores of putaminal hypointensity in DWI in the MSA group were significantly higher than in both the PD (U = 315.5, P = 0.034) and healthy control groups (U = 304.0, P = 0.022). Uni- or bilateral putaminal hypointensity in DWI with a score ≥2 was identified in 53.3% (16/30), 16.7% (5/30), and 13.3% (4/30) of MSA, PD, and healthy controls, respectively, with significant differences between MSA and PD (X2 = 8.864, P = 0.003) or healthy controls (X2 = 10.800, P = 0.001). Notably, the “black straight-line sign” of the putamen was observed in 16/30 (sensitivity 53.3%) patients with MSA, while it was absent in PD and healthy controls (specificity 100%). There were no significant differences for the presence of “black straight-line sign” in the MSA-P and MSA-C groups (X2 = 0.433, P = 0.510).ConclusionThe “black straight-line sign” of the putamen in DWI of head MRIs has the potential to serve as a diagnostic marker for distinguishing MSA from PD.

The Value of Magnetic Resonance Diffusion-Weighted Imaging and Dynamic Contrast Enhancement in the Diagnosis and Prognosis of Treatment Response in Patients with Epithelial Serous Ovarian Cancer.

Simple SummaryEpithelial ovarian cancer is one of the greatest challenges for a gynecologist and oncologist both in terms of diagnosis and treatment. Modern imaging techniques such as DWI or DCE MRI allow for better planning of the treatment strategy. This is related not only to a more precise localization of lesions, but also to the relationship between the values of DWI and DCE parameters and specific histological types of ovarian cancer. In our study, we demonstrated the previously suggested relationships between the values of DWI parameters and the types of ovarian cancer. We described the relationship with the results of immunohistochemical tests. We also showed a correlation between DWI and DCE values with time to relapse. We have made an attempt to describe such correlations in the group of patients treated with bevacizumab.Background. The aim of our study was to describe the selected parameters of diffusion-weighted imaging (DWI) and perfusion dynamic contrast enhancement (DCE) MRI in primary tumors in patients with serous epithelial ovarian cancer (EOC), as well as in disease course prognosis and treatment response, including bevacizumab maintenance therapy. Materials and Methods. In total, 55 patients with primary serous EOC were enrolled in the study. All patients underwent MR imaging using a 1.5 T clinical whole-body MR system in preoperative DWI and DCE MRI selected parameters: apparent diffusion coefficients (ADC), time to peek (TTP) and perfusion maximum enhancement (Perf. Max. En.) were measured. The data were compared with histopathological and immunochemistry results (with Ki67 and VEGF expression) and clinical outcomes. Results. Higher mean ADC values were found in low-grade EOC compared to high-grade EOC: 1151.27 vs. 894,918 (p < 0.0001). A negative correlation was found between ADC and Ki67 expression (p = 0.027), and between ADC and VEGF expression (p = 0.042). There was a negative correlation between TTP and PFS (p = 0.0019) and Perf. Max. En. and PSF (p = 0.003). In the Kaplan–Meier analysis (log rank), a longer PFS was found in patients with ADC values greater than the median; p = 0.046. The Kaplan–Meier analysis showed a longer PFS (p = 0.0126) in a group with TTP below the mean value for this parameter in patients who received maintenance treatment with bevacizumab. Conclusions. The described relationships between PFS and DCE and DWI allow us to hope to include these parameters in the group of EOC prognostic factors. This aspect seems to be of particular interest in the case of the association of PFS with DCE values in the group of patients treated with bevacizumab.

Value of Diffusion-Weighted Imaging and Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Prediction of Treatment Outcomes in Nasopharyngeal Carcinoma

Magnetic resonance imaging (MRI) parameters that reflect the tumor microenvironment of nasopharyngeal carcinoma (NPC) may predict treatment response and facilitate treatment planning. This study aimed to evaluate the diffusion-weighted imaging and dynamic contrast-enhanced MRI (DCE-MRI) values for predicting the treatment outcomes in NPC patients. Eighty-three patients with NPC underwent pretreatment MRI simulation with diffusion-weighted imaging and dynamic contrast-enhanced MRI. Average values of the apparent diffusion coefficient (ADC), Ktrans, Kep, Ve, Vp, and tumor volume of the primary tumors were measured. Other potential clinical characteristics (age, sex, staging, pathology, pretreatment Epstein-Barr virus level, and treatment type) were analyzed. Patients underwent follow-up imaging 6 months after treatment initiation. Treatment responses were assigned according to the Response Evaluation Criteria in Solid Tumors guideline (version 1.1). Fifty-one patients showed complete response (CR), whereas 32 patients did not (non-CR). Univariable logistic regression with variables dichotomized by optimal cutoff values showed that ADC ≥1.45 × 10 -3 mm 2 /s, Vp ≥0.14, tumor volume of ≥14.05 mL, high stage (stages III and IV), and Epstein-Barr virus level of ≥2300 copies/mL were predictors of non-CR ( P = 0.008, 0.05, 0.01, 0.009, and 0.04, respectively). The final multivariable model, consisting of a combination of ADC ≥1.45 × 10 -3 mm 2 /s, Vp ≥0.14, and high stage, could predict non-CR with a good discrimination ability (area under the receiver operating characteristic curve, 0.76 [95% confidence interval, 0.66-0.87]; sensitivity, 62.50%; specificity, 80.39%; and accuracy 73.49%). A multivariable prediction model using a combination of ADC ≥1.45 × 10 -3 mm 2 /s, Vp ≥0.14, and high stage can be effective for treatment response prediction in NPC patients.

Application of Multimodal Fusion Technology in Image Analysis of Pretreatment Examination of Patients with Spinal Injury.

As one of the most common imaging screening techniques for spinal injuries, MRI is of great significance for the pretreatment examination of patients with spinal injuries. With rapid iterative update of imaging technology, imaging techniques such as diffusion weighted magnetic resonance imaging (DWI), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and magnetic resonance spectroscopy are frequently used in the clinical diagnosis of spinal injuries. Multimodal medical image fusion technology can obtain richer lesion information by combining medical images in multiple modalities. Aiming at the two modalities of DCE-MRI and DWI images under MRI images of spinal injuries, by fusing the image data under the two modalities, more abundant lesion information can be obtained to diagnose spinal injuries. The research content includes the following: (1) A registration study based on DCE-MRI and DWI image data. To improve registration accuracy, a registration method is used, and VGG-16 network structure is selected as the basic registration network structure. An iterative VGG-16 network framework is proposed to realize the registration of DWI and DCE-MRI images. The experimental results show that the iterative VGG-16 network structure is more suitable for the registration of DWI and DCE-MRI image data. (2) Based on the fusion research of DCE-MRI and DWI image data. For the registered DCE-MRI and DWI images, this paper uses a fusion method combining feature level and decision level to classify spine images. The simple classifier decision tree, SVM, and KNN were used to predict the damage diagnosis classification of DCE-MRI and DWI images, respectively. By comparing and analyzing the classification results of the experiments, the performance of multimodal image fusion in the auxiliary diagnosis of spinal injuries was evaluated.

MRI-based texture analysis for differentiate between pediatric posterior fossa ependymoma type A and B

PurposeThe aim of the study was to evaluate the feasibility of texture analysis in differentiating between posterior fossa ependymoma type A (PF-EPN-A) and type B (PF-EPN-B) among children. Materials and MethodsOur retrospective study included 43 patients (37 PF-EPN-A and 6 PF-EPN-B) who were pathologically diagnosed with ependymomas in the posterior fossa. The texture features were extracted automatically from the volume of interests (VOIs), which were manually delineated on fluid-attenuated inversion recovery (FLAIR), contrast-enhanced T1-weighted (T1C), and diffusion-weighted imaging (DWI) MRI sequences. A receiver operating characteristic curve (ROC) was built to assess the diagnostic value of the texture parameters, and the prognostic value was evaluated by survival analysis. ResultsTexture parameter [Wavelet-LHH (H: High pass filter, L: Low pass.filter)_glcm (gray-level co-occurrence matrix)_Idn (Inverse difference normalized)] provides valuable information in distinguishing subgroups of ependymomas with higher specificity and positive predictive value (PPV). A total of 27 patients were divided into a high-risk group (IDN value＞0.916) and a low-risk group (IDN value＜0.916) with the most optimistic cut-off value (0.916). The Kaplan–Meier analysis of the survival curves showed significantly longer disease-free survival for low-risk groups compared to high-risk groups [hazard ratio (HR): 0.28, 95% confidence interval (CI): 0.11–0.69; p = 0.017]. ConclusionOur results suggested that the texture parameters based on DWI images can be used to differentiate PF-EPN-A from PF-EPN-B. Texture analysis could be used as a noninvasive tool in distinguishing subgroup pediatric posterior fossa ependymomas and provide reliable prognostic information upon the verification of its reproducibility and feasibility by further studies.

Quantitative Dynamic-Enhanced MRI and Intravoxel Incoherent Motion Diffusion-Weighted Imaging for Prediction of the Pathological Response to Neoadjuvant Chemotherapy and the Prognosis in Locally Advanced Gastric Cancer.

BackgroundThis study aimed to explore the predictive value of quantitative dynamic contrast-enhanced MRI (DCE-MRI) and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) quantitative parameters for the response to neoadjuvant chemotherapy (NCT) in locally advanced gastric cancer (LAGC) patients, and the relationship between the prediction results and patients’ prognosis, so as to provide a basis for clinical individualized precision treatment.MethodsOne hundred twenty-nine newly diagnosed LAGC patients who underwent IVIM-DWI and DCE-MRI pretreatment were enrolled in this study. Pathological tumor regression grade (TRG) served as the reference standard of NCT response evaluation. The differences in DCE-MRI and IVIM-DWI parameters between pathological responders (pR) and pathological non-responders (pNR) groups were analyzed. Univariate and multivariate logistic regressions were used to identify independent predictive parameters for NCT response. Prediction models were built with statistically significant quantitative parameters and their combinations. The performance of these quantitative parameters and models was evaluated using receiver operating characteristic (ROC) analysis. Clinicopathological variables, DCE-MRI and IVIM-DWI derived parameters, as well as the prediction model were analyzed in relation to 2-year recurrence-free survival (RFS) by using Cox proportional hazards model. RFS was compared using the Kaplan–Meier method and the log-rank test.ResultsSixty-nine patients were classified as pR and 60 were pNR. Ktrans, kep, and ve values in the pR group were significantly higher, while ADCstandard and D values were significantly lower than those in the pNR group. Multivariate logistic regression analysis demonstrated that Ktrans, kep, ve, and D values were independent predictors for NCT response. The combined predictive model, which consisted of DCE-MRI and IVIM-DWI, showed the best prediction performance with an area under the curve (AUC) of 0.922. Multivariate Cox regression analysis showed that ypStage III and NCT response predicted by the IVIM-DWI model were independent predictors of poor RFS. The IVIM-DWI model could significantly stratify median RFS (52 vs. 15 months) and 2-year RFS rate (72.3% vs. 21.8%) of LAGC.ConclusionPretreatment DCE-MRI quantitative parameters Ktrans, kep, ve, and IVIM-DWI parameter D value were independent predictors of NCT response for LAGC patients. The regression model based on baseline DCE-MRI, IVIM-DWI, and their combination could help RFS stratification of LAGC patients.

(Un)common space in infant neuroimaging studies: A systematic review of infant templates.

In neuroimaging, spatial normalization is an important step that maps an individual's brain onto a template brain permitting downstream statistical analyses. Yet, in infant neuroimaging, there remain several technical challenges that have prevented the establishment of a standardized template for spatial normalization. Thus, many different approaches are used in the literature. To quantify the popularity and variability of these approaches in infant neuroimaging studies, we performed a systematic review of infant magnetic resonance imaging (MRI) studies from 2000 to 2020. Here, we present results from 834 studies meeting inclusion criteria. Studies were classified into (a) processing data in single subject space, (b) using an off the shelf, or “off the shelf,” template, (c) creating a study specific template, or (d) using a hybrid of these methods. We found that across the studies in the systematic review, single subject space was the most used (no common space). This was the most used common space for diffusion‐weighted imaging and structural MRI studies while functional MRI studies preferred off the shelf atlases. We found a pattern such that more recently published studies are more commonly using off the shelf atlases. When considering special populations, preterm studies most used single subject space while, when no special populations were being analyzed, an off the shelf template was most common. The most used off the shelf templates were the UNC Infant Atlases (24%). Using a systematic review of infant neuroimaging studies, we highlight a lack of an established “standard” template brain in these studies.

The Yield of Computerized Tomography, Perfusion Computerized Tomography and Diffusion-Weighted Magnetic Resonance Image in Patients Presenting with Transient Ischemic Attack and Acute Ischaemic Stroke

Background: A transient ischaemic attack (TIA) or acute ischaemic stroke (AIS) with transient symptoms can presage a debilitating acute ischaemic stroke and some stroke mimics can have undesired consequences if not diagnosed and treated promptly. The use of computerized tomography (CT), perfusion computerised tomography (P-CT) and diffusion weighted magnetic resonance imaging (DW-MRI) is critical in facilitating early diagnosis and subsequent management of patients with acute focal neurological dysfunctions. Aim: This study investigated the yield of computerised tomography (CT), Perfusion-CT(P-CT), and Diffusion weighted-MRI(DW-MRI) scans in patients Diagnosed with TIA and AIS. Methodology: This is a retrospective cohort study of 162 cases of TIA (55%) and acute ischaemic stroke (AIS), who presented to Goulburn Valley Hospital in Shepparton from January to December 2021. Microsoft EXCEL software was used for statistical analysis. The chi-square test with Yates' correction was used to compare propositions, and a p-value of &lt; 0.05 is considered statistically significant. Results: The male to female ratio was 1.5 to 1, with a mean age of 74 years. The initial CT brain was normal in all 89 TIA patients, while 69.8% of the 63 AIS patients had infarct. 95% of AIS (n=41) patients had perfusion abnormalities on P-CT compared to only 17% of TIA patients (n=71) (P&lt;0.00001). Similarly, 94% of AIS (n=35) compared to 18% of TIA (n=55) patients had diffusion weighted abnormality on DW-MRI (p&lt;0.00001).13.5% of the TIA case(n=5) and 100% of the AIS(n=5) with normal CT and P-CT had diffusion abnormality on DW-MRI. Among the 4 TIA cases that had DW-MRI after normal CT and positive P-CT only 20% (n=1) showed diffusion abnormality. On CT carotid and cerebral angiograms, 49% of TIA (n=37) compared to 76% of AIS (n=55) patients had significant stenosis of over 50% (p&lt;0.01). Conclusion: Normal initial CT brain is a valuable initial test for differentiating TIA from AIS in patients with acute focal neurologic dysfunctions. The addition of P-CT and DW-MRI imaging demonstrated abnormalities in most of those with AIS when compared with those with TIA. Although a small percentage of those with TIA had abnormalities on P-CT and DW-MRI these two modalities add value to investigation of TIA. Therefore, the use of P-CT and DW-MRI are pertinent when the initial CT brain is normal as they are more sensitive in demonstrating abnormalities than plain CT.

Integrated PET/MRI With 68Ga-DOTATATE and 18F-FDG in Pheochromocytomas and Paragangliomas: An Initial Study.

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors with metastatic potential. Both 68Ga-DOTATATE and 18F-FDG PET/CT scans have been demonstrated to have important roles in imaging PPGLs, but less is known about the performance of PET/MRI for PPGLs. The study is aimed to investigate whether diffusion-weighted imaging-MRI (DWI-MRI) has an added value to PET imaging in the identification of PPGL lesions by means of integrated PET/MRI. Eleven patients who underwent both 18F-FDG and 68Ga-DOTATATE PET/MRI within 2 weeks were retrospectively included in the study. A total of 56 PPGL lesions were analyzed, and lesion-based detection rates of 68Ga-DOTATATE PET, 18F-FDG PET, DWI-MRI, and PET/MRI were calculated and compared, respectively. 68Ga-DOTATATE PET was superior to 18F-FDG PET and DWI-MRI in imaging PPGLs with a lesion-based detection rate of 96.4% (54/56) (95% confidence interval [CI], 87.7%-99.6%), 85.7% (48/56) (95% CI, 76.3%-95.2%), and 89.3% (50/56) (95% CI, 80.9%-97.6%), respectively. PET/MRI with DWI could improve the detection rate of 68Ga-DOTATATE and 18F-FDG PET alone up to 100% in metastatic PPGLs. Lesions of PPGL demonstrated markedly higher tracer uptake in 68Ga-DOTATATE PET than in 18F-FDG PET (P = 0.009 for primary lesion, P = 0.033 for metastases). 68Ga-DOTATATE PET showed a higher detection rate than 18F-FDG for PPGLs. In integrated PET/MRI, MRI had an added value to 18F-FDG PET but not much to 68Ga-DOTATATAE PET in identifying PPGL lesions.

Abstract WP259: Acute Stroke Neuroprotection With Intravenous Rns60 In The Cynomolgus Macaque

Introduction: RNS60 is an experimental therapy comprised of stable oxygenated nanobubbles in a sodium chloride solution with an oxygen content of 55+/-5 ppm. Phase I/II clinical trials established a safety profile for RNS60 in patients with ALS and MS. In-vitro assays in neurons have demonstrated mitochondrial biogenesis with RNS60. Therefore, we hypothesized that RNS60 would protect the ischemic penumbra and delay stroke evolution. In this study, we assessed RNS60 in a cynomolgus macaque (CM) model of transient middle cerebral artery occlusion (MCAO). Methods: Experimenters were blinded and CMs randomly allocated to treatment. In the first experiment, 22 male CMs (2.6+/-0.55 kg) were anesthetized with physiologic monitoring and MCAO followed by immediate MRI imaging to define perfusion deficit. RNS60 (5cc/kg/h IV over 1h followed by 2.5cc/kg/h for 48h) or drug vehicle were administered starting 1h following MCAO. MCA was reperfused 90min after MCAO. CMs underwent MRI diffusion-weighted (DWI) and T2 imaging at 48h and 30d after MCAO. Serial Non-Human Primate Stroke Scale (NHPSS) assessments were collected over 30 days following MCAO. In the second experiment, 10 male CMs (4.95+/-0.18 kg) underwent permanent MCAO. RNS60 or drug vehicle were infused starting 5 minutes after MCAO (5cc/kg/h IV for 1 hour followed by 2.5cc/kg/h until sacrifice). Perfusion and DWI MRI images were obtained serially over 6 hours to measure the evolution of the penumbra. CMs were sacrificed at the completion of the experiment. Results: DWI stroke volume was significantly reduced 4.3+/-1.1mL vs. 9.1+/-0.92mL (P=0.0036) at 48 hours post MCAO in RNS60 vs. placebo treated CMs. This result was conserved on T2 imaging at 30 days where stroke volume was 3.5+/-0.86mL vs. 7.3+/-0.79mL (P=0.004). RNS60 significantly improved NHPSS scores over 30 days compared to controls after removing three outlier CMs (2 mortalities and one non-reperfused MCA). The results of the second experiment demonstrated a 6h DWI volume of 5.9cc in RNS60 treated CMs compared to 10.6cc in controls. Conclusion: RNS60 administered during acute ischemic stroke significantly reduces stroke volume and improves functional outcomes in male CMs. The evolution of penumbra to stroke is slowed following RNS60 administration.

Abstract WMP78: Microstructural Alterations And Vascular Dysfunction In Cerebral Amyloid Angiopathy

Background: Cerebral amyloid angiopathy (CAA) causes impaired vascular reactivity to physiologic stimuli that mediates CAA-related white matter hyperintensities (WMH) but its relationship to microstructural changes has not yet been tested. We hypothesized that the degree of vascular dysfunction would be associated with alterations in white matter microstructure in patients with CAA. Methods: Fifty-five non-demented probable CAA patients underwent high-resolution structural MRI including Diffusion-Weighted Imaging (DWI) and functional MRI (fMRI). WMH volume was quantified and expressed as percent of total intracranial volume (pWMH). Vascular reactivity was measured as the amplitude of the blood-oxygenation-level-dependent response (BOLD_Amp) to a visual stimulus. Peak Width of Skeletonized Mean Diffusivity (PSMD) was calculated from DWI and used as a marker of microstructural integrity. Results: Patients had a mean age of 69.3±7.4 years and 36 (65%) had intracerebral hemorrhage (ICH). The mean PSMD was [(3.92±0.8) х 10–4 mm2/s] and the mean BOLD_Amp was 1.15±0.2%. Neither PSMD nor BOLD_Amp differed between patients with ICH and those without (p&gt;0.2 for all comparisons). PSMD significantly correlated with older age (r=0.335, p=0.012), with higher pWMH (r=0.792, p&lt;0.001) and with lower BOLD_Amp (r= –0.5, p&lt;0.001). PSMD showed a trend to increase more in patients with hypertension (HT) than without ([(4.09±0.8) х 10–4 mm2/s] vs. ([(3.74±0.8) х 10–4 mm2/s], p=0.097). BOLD_Amp also correlated with pWMH (r= –0.409, p=0.002). In a linear regression analysis, decrease in BOLD_Amp was independently associated with increased PSMD corrected for age, sex, HTN, ICH and pWMH (β= –0.91, 95%CI (–1.77)-(–0.05), p=0.037). pWMH was also associated with PSMD in this model (β=1.22, 95%CI 0.89-1.54, p&lt;0.001). Conclusion: This study supports the view that vascular dysfunction in CAA is closely linked with CAA-related global ischemic injury including MRI-visible white matter injury as well as microstructural tissue disruption.

Renal Cell Carcinoma or Oncocytoma? The Contribution of Diffusion-Weighted Magnetic Resonance Imaging to the Differential Diagnosis of Renal Masses.

Background and Objectives: Renal Cell Carcinoma (RCC) accounts for 85% and oncocytomas constitute 3–7% of solid renal masses. Oncocytomas can be confused, especially with hypovascular RCC. The purpose of this research was to evaluate the contribution of diffusion-weighted imaging (DWI) and contrast-enhanced MRI sequences in the differential diagnosis of RCC and oncocytoma Materials and Methods: 465 patients with the diagnosis of RCC and 45 patients diagnosed with oncocytoma were retrospectively reviewed between 2009 to 2020. All MRI acquisitions were handled by a 1.5 T device (Achieva, Philips Healthcare, Best, The Netherlands) and all images were evaluated by the consensus of two radiologists with 10–15 years’ experience. The SPSS package program version 15.0 software was used for statistical analysis of the study. Chi-square test, Mann–Whitney U test or the Kruskal–Wallis tests were used in the statistical analysis. A receiver operating characteristic (ROC) curve was used to calculate the cut-off values Results: The results were evaluated with a 95% confidence interval and a significance threshold of p < 0.05. ADC values (p < 0.001) and enhancement index (p < 0.01) were significantly lower in the RCC group than the oncocytoma group. Conclusion: DWI might become an alternative technique to the contrast-enhanced MRI in patients with contrast agent nephropathy or with a high risk of nephrogenic systemic fibrosis, calculation of CI of the oncocytoma and RCCs in the contrast-enhanced acquisitions would contribute to the differential diagnosis.