Diffusion-weighted Imaging Signal Research Articles

Comparison of Diffusion MRI Findings of High-Graded Primary Brain Tumors and Metastatic Brain Tumors

Aim: Glioblastomas are the highest grade and most mortal primary brain tumors. Cerebral masses that occur with the metastasis of cancers of tissues other than brain are included in the differential diagnosis of glioblastomas. This study aimed to compare the diffusion-weighted imaging signal characteristics of primary and metastatic brain masses and to describe the findings that may be useful in the differential diagnosis. Material and Methods: Patients with pathologically diagnosed glioblastoma and patients with pathologically diagnosed metastases or radiologically diagnosed brain metastases were included in the study. Diffusion-weighted imaging signal properties in magnetic resonance imaging examinations obtained with a 1.5 Tesla scanner were retrospectively analyzed. The signal features and short and long diameters of the lesions were measured and compared in both patient groups. Results: A total of 54 patients, 24 glioblastomas, and 30 brain metastases were included in the study. The most common signal feature of diffusion-weighted imaging in the glioblastoma group was heterogeneous hyper- and hypointense areas observed in 20 (83.3%) patients. The most common signal feature in the metastasis group was the peripheral hyperintense ring and central hypointense signal in 16 (53.3%) patients. There was no significant relation found between the number of lesions and the primary brain tumor and metastases. Conclusion: Although only signal characteristics are used without quantitative assessment in diffusion-weighted imaging, it may be helpful in the differential diagnosis of primary and metastatic brain masses. It is important to remember that the masses in the two groups can have comparable signal properties.

Diffusion-weighted imaging as a potential non-gadolinium alternative for immediate assessing the hyperacute outcome of MRgFUS ablation for uterine fibroids.

The aim of this study was to investigate the value of diffusion-weighted imaging (DWI) as a potential non-gadolinium alternative for promptly assessing the hyperacute outcome of magnetic resonance-guided focused ultrasound (MRgFUS) treatment for uterine fibroids. In this retrospective study we included 65 uterine fibroids from 44 women, who underwent axial DWI (b-value: 800s/mm2) and contrast-enhanced (CE) MR within 15min post-ablation. Two blinded observers independently reviewed the DWI findings of ablated necrotic lesions and measured their volumes on DWI and CE images. The post-ablation DWI images revealed clear depiction of ablative necrotic lesions in all fibroids, which were classified into two types: the bull's eye sign (type 1) and the bright patch sign (type 2). The inter-observer intraclass correlation coefficient for classifying DWI signal types was 0.804 (p < 0.001). Volumetric analysis of ablated necrosis using DWI and CE T1-weighted imaging showed no significant variance, nor did the non-perfused volume ratios (all p > 0.05). Bland-Altman analysis revealed a mean difference of 2.38% and 1.71% in non-perfused volume ratios between DWI and CE, with 95% limits of agreement from - 19.06 to 23.82% and - 18.40 to 21.82%, respectively. The findings of this study support the potential of DWI as a viable non-gadolinium alternative for evaluating the hyperacute outcomes of MRgFUS ablation in uterine fibroids.

Normal bone marrow signal characteristics in whole-body diffusion-weighted images of amateur marathon runners.

Marathon training can reverse bone marrow conversion; however, little is known about the normal bone marrow whole-body diffusion-weighted imaging (WB-DWI) signal characteristics of amateur marathon runners. If marathon training can cause diffuse hyperintensity of bone marrow on WB-DWI is essential for correctly interpreting the diffusion-weighted (DW) images. This study sought to evaluate the WB-DWI signal characteristics of normal bone marrow in amateur marathon runners. In this prospective cross-sectional study, 30 amateur marathon runners who had trained for over 3 years for regular or half-marathon races and had a running frequency of more than 20 days a month at a distance of more than 100 km per month from the Chengde Marathon Outdoor Sports Association in Hebei, China, and 30 age- and gender-matched, healthy volunteers (the control group) who had no long-term heavy-load sports history were recruited between April 2021 to September 2021. All the subjects underwent WB-DWI (b-value: 0, 800 s/mm2) and lumbar vertebral transverse relaxation time (T2) mapping. The bone marrow WB-DWI signal characteristics were analyzed visually and statistically by chi-square (χ2) tests. The apparent diffusion coefficient (ADC), DWI signal intensity, and T2 values of the bone marrow were quantitatively and statistically analyzed by the independent sample t-test and Mann-Whitney U test. No subjects were excluded from the study. The bone marrow of 30 of the 60 subjects (aged 30-50 years) showed diffuse hyperintensity in the DW images. However, in all 60 subjects, the humeral heads, femoral heads, and great trochanters had low signals. The frequency of diffuse bone marrow DWI hyperintensity was significantly higher in the male amateur marathon runners (50%) than the male controls (5%, P=0.003), but no such significant difference was found between the female amateur marathon runners (100%) and female controls (90%, P>0.99). The DW signal intensity ratios of bone marrow to muscle (SIRBM-muscle) were significantly higher in the male amateur marathon runners than the male controls in the thoracic vertebrae (4.68 vs. 3.57, P=0.021), lumbar vertebrae (4.49 vs. 3.01, P<0.001), sacrum (3.67 vs. 2.62, P=0.002), and hip (3.45 vs. 2.50, P=0.002), but were only significantly higher in the female amateur marathon runners than the female controls in the thoracic vertebrae (7.69 vs. 5.87, P=0.029) and hip (4.76 vs. 3.92, P=0.004). The mean T2 values of the lumbar vertebrae were significantly higher in the male amateur marathon runners than the male controls (116.76 vs. 97.63 ms, P=0.001), but no such significant difference was observed between the female amateur marathon runners and the corresponding controls (118.58 vs. 124.10 ms, P=0.386). Marathon training resulted in diffuse hyperintensity in the bone marrow based on WB-DWI in 50% of the male amateur marathon runners aged 30-50 years. Thus, when WB-DWI is used for bone marrow disease screening, marathon training history should be considered to avoid false-positive diagnoses.

DWI scrolling artery sign for the diagnosis of giant cell arteritis: a pattern recognition approach

ObjectivesTo investigate the diagnostic accuracy of a pattern recognition approach for the evaluation of MRI scans of the head with diffusion-weighted imaging (DWI) in suspected giant cell arteritis (GCA).MethodsRetrospectively, 156...

Intravoxel incoherent motion diffusion-weighted imaging for predicting kidney allograft function decline: comparison with clinical parameters

ObjectiveTo evaluate the added benefit of diffusion-weighted imaging (DWI) over clinical parameters in predicting kidney allograft function decline.MethodsData from 97 patients with DWI of the kidney allograft were retrospectively analyzed. The DWI signals were analyzed with both the mono-exponential and bi-exponential models, yielding total apparent diffusion coefficient (ADCT), true diffusion (D), pseudo-diffusion (D*), and perfusion fraction (fp). Three predictive models were constructed: Model 1 with clinical parameters, Model 2 with DWI parameters, and Model 3 with both clinical and DWI parameters. The predictive capability of each model was compared by calculating the area under the receiver-operating characteristic curve (AUROC).ResultsForty-five patients experienced kidney allograft function decline during a median follow-up of 98 months. The AUROC for Model 1 gradually decreased with follow-up time > 40 months, whereas Model 2 and Model 3 maintained relatively stable AUROCs. The AUROCs of Model 1 and Model 2 were not statistically significant. Multivariable analysis showed that the Model 3 included cortical D (HR = 3.93, p = 0.001) and cortical fp (HR = 2.85, p = 0.006), in addition to baseline estimated glomerular filtration rate (eGFR) and proteinuria. The AUROCs for Model 3 were significantly higher than those for Model 1 at 60-month (0.91 vs 0.86, p = 0.02) and 84-month (0.90 vs 0.83, p = 0.007) follow-up.ConclusionsDWI parameters were comparable to clinical parameters in predicting kidney allograft function decline. Integrating cortical D and fp into the clinical model with baseline eGFR and proteinuria may add prognostic value for long-term allograft function decline.Critical relevance statementOur findings suggested that cortical D and fp derived from IVIM-DWI increased the performance to predict long-term kidney allograft function decline. This preliminary study provided basis for the utility of multi-b DWI for managing patients with a kidney transplant.Key points• Both clinical and multi-b DWI parameters could predict kidney allograft function decline.• The ability to predict kidney allograft function decline was similar between DWI and clinical parameters.• Cortical D and fp derived from IVIM-DWI increased the performance to predict long-term kidney allograft function decline.Graphical

Clinical factors for delayed neuropsychiatric sequelae from acute carbon monoxide poisoning: a retrospective study.

Delayed neuropsychiatric sequelae (DNS), which seriously affect the daily lives of patients, are the most common complications of carbon monoxide (CO) poisoning. No uniform screening tool is available for identifying high-risk groups. Therefore, in this study, we aimed to explore whether conventional laboratory indicators and imaging data from primary hospitals could predict the occurrence of DNS. This retrospective observational study was conducted in a single-center primary hospital from January 1, 2021 to May 31, 2023. Participants included patients aged >18 years with acute CO poisoning. Patients with complete recovery in the acute phase were followed up by telephone and outpatient visits, and the presence of DNS was determined according to the occurrence of new neurological symptoms within 6 weeks after discharge. We obtained demographic, laboratory, and imaging data from the medical records and performed a univariate analysis. A multivariate logistic regression model was used to identify independent clinical predictors of DNS. A total of 73 patients were included in the study, of whom 25 (34.2%) developed DNS. Multivariate logistic regression analysis revealed that a longer duration of CO exposure (adjusted odds ratio (AOR): 1.262, 95% confidence interval (CI): 1.069-1.490) and the presence of acute brain lesions on diffusion-weighted imaging (DWI) (AOR: 5.117, 95% CI: 1.430-18.315) were independent risk factors for DNS. Receiver operating characteristic analyses of the duration of CO exposure were performed (area under the curve (AUC): 0.825; 95% CI: 0.731-0.918) with a cut-off value of 5.5 h, and DNS was predicted with a sensitivity of 96% and a specificity of 66.7%. High cranial DWI signal within 24 h and duration of poisoning longer than 5.5 h are independent predictors of DNS. The predictive effects of conventional laboratory indicators require further standardized and large-sample studies.

Feasibility of Diffusion-weighted Imaging (DWI) for Assessing Cerebrospinal Fluid Dynamics: DWI-fluidography in the Brains of Healthy Subjects.

The present study aimed to investigate whether diffusion-weighted imaging (DWI) can qualify and quantify cerebrospinal fluid (CSF) dynamics in the brains of healthy subjects. For this purpose, we developed new DWI-based fluidography and compared the CSF dynamics seen on the fluidography with two apparent diffusion coefficients obtained with different DWI signal models at anatomical spaces filled by CSF. DWI with multiple b values was performed for 10 subjects using a 7T MRI scanner. DWI-fluidography based on the DWI signal variations in different motion probing gradient directions was developed for visualizing the CSF dynamics voxel-by-voxel. DWI signals were measured using an ROI in the representative CSF-filled anatomical spaces in the brain. For the multiple DWI signals, the mono-exponential and kurtosis models were fitted and two kinds of apparent diffusion coefficients (ADCC and ADCK) were estimated in each space using the Gaussian and non-Gaussian diffusion models, respectively. DWI-fluidography could qualitatively represent the features of CSF dynamics in each anatomical space. ADCs indicated that the motions at the foramen of Monro, the cistern of the velum interpositum, the quadrigeminal cistern, the Sylvian cisterns, and the fourth ventricle were more drastic than those at the subarachnoid space and anterior horns of the lateral ventricle. Those results seen in ADCs were identical to the findings on DWI-fluidography. DWI-fluidography based on the features of DWI signals could show differences of CSF dynamics among anatomical spaces.

Insights and improvements in correspondence between axonal volume fraction measured with diffusion-weighted MRI and electron microscopy.

Biophysical diffusion-weighted imaging (DWI) models are increasingly used in neuroscience to estimate the axonal water fraction ( ), which in turn is key for noninvasive estimation of the axonal volume fraction ( ). These models require thorough validation by comparison with a reference method, for example, electron microscopy (EM). While EM studies often neglect the unmyelinated axons and solely report the fraction of myelinated axons, in DWI both myelinated and unmyelinated axons contribute to the DWI signal. However, DWI models often include simplifications, for example, the neglect of differences in the compartmental relaxation times or fixed diffusivities, which in turn might affect the estimation of . We investigate whether linear calibration parameters (scaling and offset) can improve the comparability between EM- and DWI-based metrics of . To this end, we (a) used six DWI models based on the so-called standard model of white matter (WM), including two models with fixed compartmental diffusivities (e.g., neurite orientation dispersion and density imaging, NODDI) and four models that fitted the compartmental diffusivities (e.g., white matter tract integrity, WMTI), and (b) used a multimodal data set including ex vivo diffusion DWI and EM data in mice with a broad dynamic range of fibre volume metrics. We demonstrated that the offset is associated with the volume fraction of unmyelinated axons and the scaling factor is associated with different compartmental and can substantially enhance the comparability between EM- and DWI-based metrics of . We found that DWI models that fitted compartmental diffusivities provided the most accurate estimates of the EM-based . Finally, we introduced a more efficient hybrid calibration approach, where only the offset is estimated but the scaling is fixed to a theoretically predicted value. Using this approach, a similar one-to-one correspondence to EM was achieved for WMTI. The method presented can pave the way for use of validated DWI-based models in clinical research and neuroscience.

Quantitative evaluation of diffusion-weighted MRI for differentiating benign and malignant thyroid nodules larger than 4 cm

PurposeOur study aimed to diagnose benign or malignant thyroid nodules larger than 4 cm using quantitative diffusion-weighted imaging (DWI) analysis.MethodsEighty-two thyroid nodules were investigated retrospectively and divided them into benign (n = 62) and malignant groups (n = 20). We calculated quantitative features DWI and apparent diffusion coefficient (ADC) signal intensity standard deviation (DWISD and ADCSD), DWI and ADC signal intensity ratio (DWISIR and ADCSIR), mean ADC and minimum ADC value (ADCmean and ADCmin) and ADC value standard deviation (ADCVSD). Univariate and multivariate logistic regression were conducted to identify independent predictors, and develop a prediction model. We performed receiver operating characteristic (ROC) analysis to determine the optimal threshold of risk factors, and constructed combined threshold models. Our study calculated diagnostic performance including area under the ROC curve (AUC), accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and unnecessary biopsy rate of all models were calculated and compared them with the American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS) result.ResultsTwo independent predictors of malignant nodules were identified by multivariate analysis: DWISIR (P = 0.007) and ADCmin (P < 0.001). The AUCs for multivariate prediction model, combined DWISIR and ADCmin thresholds model, combined DWISIR and ADCSIR thresholds model and ACR-TIRADS were 0.946 (0.896–0.996), 0.875 (0.759–0.991), 0.777 (0.648–0.907) and 0.722 (0.588–0.857). The combined DWISIR and ADCmin threshold model had the lowest unnecessary biopsy rate of 0%, compared with 56.3% for ACR-TIRADS.ConclusionQuantitative DWI demonstrated favorable malignant thyroid nodule diagnostic efficacy. The combined DWISIR and ADCmin thresholds model significantly reduced the unnecessary biopsy rate.

Abstract 106: CHANTER Syndrome: A Case Report Of A 59 Year Old Man With Positive Outcome

Introduction Cerebellar, Hippocampal, and Basal Nuclei Transient Edema with Restricted Diffusion (CHANTER) syndrome was first described in 2019 [1] as a pattern of radiographic findings that are distinct from ischemic, anoxic, or toxic brain injury. Pathophysiology is still uncertain, but some proposed theories include a primary metabolic etiology or a mitochondrial failure of gray matter. Clinically, patients typically present with altered level of consciousness. Radiographically, diffusion weighted imaging shows restriction in the bilateral hippocampi, bilateral cerebelli, and basal nuclei. The cerebral cortex, thalamus, and subcortical white matter are usually spared. Despite the morbid clinical picture on presenation, positive outcomes were reported with early intervention. We describe a case of CHANTER syndrome in a 59 year old man with history of illicit substance abuse. Methods Case report with electronic medical record review. Results 59‐year‐old man with history of illicit substance abuse including cocaine, opioid, and phencyclidine presented to the hospital after being found down at a drug store. Patient did not respond to Naloxone and was eventually intubated due to respiratory compromise. Non‐contrast CT head showed hypoattenuation of the bilateral cerebellar hemispheres with mild effacement of the fourth ventricle. MRI brain showed diffusion signal abnormalities with corresponding T2 FLAIR hyperintensities in the bilateral cerebellar hemispheres, bilateral hippocampi, and bilateral basal ganglia with some involvement of the left occipital lobe suggestive of CHANTER syndrome. As vasogenic edema worsened, hydrocephalus ensued requiring administration of hypertonic saline and eventual external ventricular drain (EVD) insertion in the neurocritical care unit. Despite initial improvement in his level of consciousness after the EVD insertion, his intracranial pressure (ICP) continued to increase and midazolam and ketamine infusion drips were added. A fine balance between lowering the ICP and avoiding respiratory suppresion with sedating infusions was maintained. Consecutive MRI brain images over the course of the following 4 weeks of his stay showed decrease of the abnormal diffusion weighted imaging signal along with improvement in his overall mental status and eventual discharge 12 weeks from his initial presentation. Conclusion This case further strengthens the relationship between CHANTER syndrome and illicit substance use as a likely etiology along with other cases in the literature. Aggressive management in the neurocritical care to control vasogenic edema and avoid ICP elevation is essential to give patients the highest chance of recovery. Clinical improvement At least partial reversal of the radiographic findings of CHANTER syndrome can be attained with treatment, however, unclear if complete reversal is possible.

Magnetic resonance imaging features to evaluate the neonatal hypoglycemia brain injury and investigation of related risk factors under the fuzzy C‐means clustering intelligent algorithm

AbstractThis research was aimed to analyse the application value of magnetic resonance imaging based on Fuzzy C‐means (FCM) algorithm in neonatal hypoglycemia brain injury (HBI), and explore the risk factors related to the occurrence of brain injury in children, to provide guidance for clinical diagnosis and treatment. 114 children with hypoglycemia were divided into brain injury group (58 cases) and no brain injury group (56 cases) according to whether they had brain injury or not. The MRI image signal performance, general data, average minimum blood glucose value, duration of hypoglycemia, first feeding time, age of onset of hypoglycemia, and algorithm segmentation performance of the two groups of patients were observed and compared. Furthermore, the Logistic factor analysis was carried out to summarize the MRI characteristics and related risk factors of neonatal hypoglycemic brain injury. The results showed that the average minimum blood glucose (1.09 ± 0.53 mmoL/L) in the brain injury group was lower than that in the non‐brain injury group (1.75 ± 0.49 mmoL/L), and the duration of hypoglycemia (43.1 ± 21.07 h) was higher than that in the non‐brain injury group (13.79 ± 6.81 h), p &lt; 0.05. The first feeding time and age of hypoglycemia in the brain injury group were higher than those in the non‐brain injury group, showing a difference with p &lt; 0.05. In the brain injury group, all 58 cases showed high DWI (diffusion weighted imaging) signal at the damaged site at the early stage of MRI (magnetic resonance imaging), and 23 cases (39.66%) were involved in parieto‐occipital lobe. Image segmentation coefficient of Vpc increased significantly under FCM clustering algorithm (p &lt; 0.05). Late first feeding time, low blood sugar level, and long duration were high risk factors for hypoglycemic brain injury. In conclusion, MRI images based on FCM clustering algorithm had higher image quality. Late first feeding time, low blood sugar level, and long duration of hypoglycemia were high risk factors for hypoglycemic brain injury.

Fat embolism syndrome after humerus and pelvis fracture complicated by acute kidney injury requiring blood purification: a case report and literature review

BackgroundFat embolism syndrome (FES) is a rare syndrome that typically occurs 12–72 h after long bone or pelvic fractures with a classic triad of respiratory distress, neurologic changes, and petechial rash. Although Gurd’s criteria for FES include anuria or oliguria, the mechanism of acute kidney injury (AKI) remain unknown. Here, we present a case of FES complicated by AKI that required blood purification.Case presentationA 79-year-old woman was admitted to our hospital because of a right humerus and pelvic fracture caused by a traffic accident. On the second day of hospitalization, she developed impaired consciousness, respiratory failure, and disseminated intravascular coagulation (DIC). Chest radiography revealed bilateral diffuse alveolar infiltration. Brain magnetic resonance imaging revealed diffuse high signal intensity on diffusion-weighted imaging and diffuse low signal intensity on susceptibility-weighted imaging in the cerebral and cerebellar regions. The diagnosis of FES was confirmed and the patient was treated with methylprednisolone (40 mg/day) and ulinastatin. On the third day of hospitalization, she was admitted to our department because of AKI with oliguria. Although echocardiography showed an elevated right ventricular artery systolic pressure suggestive of pulmonary hypertension (PH), pulmonary congestion was initially considered on chest imaging, and hemodialysis and rapid ultrafiltration were initiated. However, she developed hypovolemic shock and treatment was switched to continuous hemodiafiltration and slow ultrafiltration. Thereafter, her consciousness, hypoxemia, DIC and PH completely improved. She was weaned from blood purification therapy on the 29th day of hospitalization. She had hemolytic anemia that might have been caused by thrombotic microangiopathy (TMA), but it resolved without plasmapheresis. On the 51st day of hospitalization, the patient was transferred to another hospital for rehabilitation.ConclusionsFES can be complicated by AKI. In this case, DIC, which was difficult to differentiate from TMA, and/or renal congestion were considered to be a cause of AKI. Chest radiographs of FES may be indistinguishable from pulmonary congestion. In our case, chest radiography showed bilateral diffuse alveolar infiltrates which was not indicative of pulmonary congestion but pulmonary involvement of FES. FES is associated with PH, which may lead to right heart failure. Therefore, the patient could have developed hypovolemic shock due to hemodialysis and rapid ultrafiltration. Clinicians should pay attention to the hemodynamics when blood purification for FES is performed.

The dynamic contrast enhanced-magnetic resonance imaging and diffusion-weighted imaging features of alveolar soft part sarcoma.

Alveolar soft part sarcoma (ASPS) is a rare type of soft tissue sarcoma that predominantly affects adolescents and young adults. Early diagnosis of ASPS is crucial for optimal therapeutic planning and improving prognosis, but its diagnostic features are not well delineated. This study aimed to retrospectively analyze the imaging features of ASPS with an emphasis on the dynamic contrast-enhanced-magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) findings to identify imaging findings that might suggest the diagnosis to radiologists. The imaging features of 34 patients with pathologically proven limb ASPS were retrospectively analyzed. A total of 23 underwent DCE-MRI, and 12 underwent DWI. Among the 34 cases of ASPS, 31 tumors were in the lower extremities, and 3 were in the upper extremities. The maximum tumor diameters ranged from 3.0 to 19.4 cm (mean, 8.7±3.96 cm). A total of 28 cases had well-defined borders. The masses demonstrated heterogeneous high signal intensity on T2-weighted imaging (T2WI) and the fat-suppressed (FS) T2WI sequence and slight hyperintensity on T1-weighted imaging (T1WI). A total of 25 lesions had thin hypointense bands on T1WI and T2WI. Intra- and peri-tumoral tubular areas of flow void were exhibited on both T1WI and T2WI in all cases. A total of 12 cases showed a high signal on DWI, and the mean apparent diffusion coefficient (ADC) value was (0.86±0.07)×10-3 mm2/s [range, (0.6-1.4)×10-3 mm2/s]. Persistent remarkable enhancement of the lesion was displayed on contrast-enhanced scans. The time-intensity curves (TICs) of 23 masses showed early arterial enhancement and slow washout of contrast. ASPS most commonly presents in the lower extremities of adolescents or young adults. Hyperintense T1WI, T2WI, and DWI signals, low ADC, flow voids, early arterial enhancement are frequent MRI features.

Solitary hypovascular hepatic nodules: comparison and differentiation between peripheral nodular cholangiocarcinoma and atypical liver hemangioma with MRI.

Peripheral nodular cholangiocarcinoma (PCC) and hepatic hemangioma (HG) significantly differ in treatment strategies and prognosis. However, they can present similar imaging characteristics, making them difficult to distinguish. The distinction between PCC and atypical HG using pre-operative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) holds substantial significance. Fifty-four cases of solitary hypovascular hepatic nodules (nodules ≤3 cm in diameter and enhancement not exceeding the hepatic parenchyma) confirmed pathologically were collected, including 25 cases of PCC and 29 cases of HG. The clinical and DCE-MRI features were observed, and the apparent diffusion coefficient (ADC) values were compared. The t-test or Fisher's exact test was used to compare the differences between the two groups. Receiver operating characteristic (ROC) curve analysis was performed on the diagnostic results of the two readings before and after the study by three diagnostic physicians. The signal of PCC was more heterogeneous and could be shown as a ring hyperintensity signal on diffusion weighted imaging (DWI). The T2-weighted imaging (T2WI) signal of HG lesions showed a more homogeneous high-intense signal. The ADC value of PCC patients was lower than that of HG patients. Most of the patients in the two groups presented marginal enhancement in the arterial phase with infrequent abnormal perfusion around. The intratumoral vascular traversal signs in the PCC group showed a diagnostic significance. Among the lesions with marginal enhancement at arterial stage, the enhancement in PCC group was more likely to have annular enhancement with the main manifestation of delay reduction and nebulous or separated/astral center. On the other hand, HG tended to be more likely to have nodular enhancement in the arterial phase with delayed invariance at the margins and with no significant enhancement at the center. The area under the curves (AUC) of the three radiologists before and after the two readings were 0.645 and 0.888, respectively. In the differentiation of PCC and atypical liver hemangioma, the presence of a circular hyper-intense signal in DWI, the ADC values, and the pattern and extent of enhancement of marginal and central lesions were of diagnostic significance.

Diffusion-weighted magnetic resonance imaging in early central retinal artery occlusion.

Restricted retinal diffusion (RDR) has recently been recognized as a frequent finding on standard diffusion-weighted imaging (DWI) in central retinal artery occlusion (CRAO). However, data on early DWI signal evolution are missing. Consecutive CRAO patients with DWI performed within 24 h after onset of visual impairment were included in a bicentric, retrospective cross-sectional study. Two blinded neuroradiologists assessed randomized DWI scans for the presence of retinal ischemia. RDR detection rates, false positive ratings, and interrater agreement were evaluated for predefined time groups. Sixty eight CRAO patients (68.4 ± 16.8 years; 25 female) with 72 DWI scans (76.4% 3 T, 23.6% 1.5 T) were included. Mean time-delay between onset of CRAO and DWI acquisition was 13.4 ± 7.0 h. Overall RDR detection rates ranged from 52.8% to 62.5% with false positive ratings in 4.2%-8.3% of cases. RDR detection rates were higher in DWI performed 12-24 h after onset, when compared with DWI acquired within the first 12 h (79.5%vs 39.3%, p < 0.001). The share of false positive ratings was highest for DWI performed within the first 6 h of symptom onset (up to 14.3%). Interrater reliability was "moderate" for DWI performed within the first 18 h (κ = 0.57-0.58), but improved for DWI acquired between 18 and 24 h (κ = 0.94). DWI-based detection of retinal ischemia in early CRAO is likely to be time-dependent with superior diagnostic accuracy for DWI performed 12-24 h after onset of visual impairment.

Factors associated with hearing outcomes after a middle fossa approach in 131 consecutive patients with vestibular schwannomas.

The middle fossa approach is an effective option for the treatment of small (Koos grade I and II) vestibular schwannomas (VSs) when the goal is hearing preservation. The authors evaluated the rates of hearing preservation and examined the factors associated with improved hearing outcomes after the middle fossa approach for VSs. In this retrospective, single-center cohort study evaluating the clinical outcomes after resection of small VSs using the middle fossa approach, consecutive adult patients (> 18 years) who underwent surgery between January 2000 and December 2021 were included. Clinical and imaging characteristics were analyzed, including baseline hearing status, duration of surgery, anesthetic parameters, and imaging characteristics of the surgically treated tumors. Among the 131 included patients, 102 had valid and discoverable pre- and postoperative audiology assessments. The mean follow-up was 26 months (range 1-180 months). There were 85 patients with serviceable hearing preoperatively, defined as American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B, of whom 78% retained class A or B hearing at the last follow-up. Binary logistic regression demonstrated that preoperative hearing AAO-HNS class (OR 0.19, 95% CI 0.05-0.77; p = 0.02), overlap between fundus and cochlea (OR 0.32, 95% CI 0.11-0.96; p = 0.04), and duration of anesthesia (OR 0.98, 95% CI 0.97-0.99; p = 0.03) were independent predictors of hearing outcomes. Additionally, 75% of patients with high diffusion-weighted imaging signal in the tumor (p = 0.009) and 67% of patients with the tumor originating at the modiolus of the cochlea (p = 0.004) had poor hearing outcomes. The hearing preservation rates after microsurgical resection of small VSs using the middle fossa approach are high, with 78% of patients maintaining AAO-HNS class A or B hearing. Poor hearing status at baseline, longer duration of anesthesia, and large overlap between the fundus of the internal auditory canal and the cochlea were independently associated with unfavorable hearing outcomes. Imaging characteristics can be used to stratify patients' risk of hearing loss.

Diffusion-weighted Imaging of the Chest: A Primer for Radiologists.

Diffusion-weighted imaging (DWI) is a fundamental sequence not only in neuroimaging but also in oncologic imaging and has emerging applications for MRI evaluation of the chest. DWI can be used in clinical practice to enhance lesion conspicuity, tissue characterization, and treatment response. While the spatial resolution of DWI is in the order of millimeters, changes in diffusion can be measured on the micrometer scale. As such, DWI sequences can provide important functional information to MRI evaluation of the chest but require careful optimization of acquisition parameters, notably selection of b values, application of parallel imaging, fat saturation, and motion correction techniques. Along with assessment of morphologic and other functional features, evaluation of DWI signal attenuation and apparent diffusion coefficient maps can aid in tissue characterization. DWI is a noninvasive noncontrast acquisition with an inherent quantitative nature and excellent reproducibility. The outstanding contrast-to-noise ratio provided by DWI can be used to improve detection of pulmonary, mediastinal, and pleural lesions, to identify the benign nature of complex cysts, to characterize the solid portions of cystic lesions, and to classify chest lesions as benign or malignant. DWI has several advantages over fluorine 18 (18F)-fluorodeoxyglucose PET/CT in the assessment, TNM staging, and treatment monitoring of lung cancer and other thoracic neoplasms with conventional or more recently developed therapies. © RSNA, 2023 Quiz questions for this article are available in the supplemental material. Supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Exploration of the influence of early rehabilitation training on circulating endothelial progenitor cell mobilization in patients with acute ischemic stroke and its related mechanism under a lightweight artificial intelligence algorithm.

This work aimed to explore the application of lightweight artificial intelligence algorithms in magnetic resonance imaging (MRI) image processing of patients with acute ischemic stroke (AIS) to clarify the effect and mechanism of early rehabilitation training on the mobilization of circulating endothelial progenitor cells (EPCs) in AIS. A total of 98 AIS patients undergoing MRI examination were selected as the research objects and were randomly divided into a rehabilitation group (early rehabilitation training, 50 cases) and a routine group (conventional treatment, 48 cases) by random number table method and lottery method. In this work, based on the convolutional neural network (CNN) algorithm, a low-rank decomposition algorithm was introduced to optimize it, and a lightweight MRI image computer intelligent segmentation model (LT-RCNN) was established. The LT-RCNN model was used in the MRI image processing of AIS patients, and the role of the model in AIS image segmentation and lesion localization was analyzed. Furthermore, flow cytometry was used to detect the number of peripheral circulating EPCs and CD34+KDR+ cells in the two groups of patients before and after treatment. The serum levels of vascular endothelial growth factor (VEGF), tumor necrosis factor-α (TNF-α), interleukin 10 (IL-10), and stromal cell-derived factor-1α (SDF-1α) content were detected by Enzyme-Linked Immunosorbent Assay (ELISA). In addition, the correlation between each factor and CD34+KDR+ was analyzed by Pearson linear correlation. The diffusion-weighted imaging (DWI) signal of MRI images of AIS patients under the LT-RCNN model was high. The location of the lesion could be accurately detected, and the contour of the lesion could be displayed and segmented, and the segmentation accuracy and sensitivity were significantly better than before optimization. The number of EPCs and CD34+KDR+ cells in the rehabilitation group was increased compared with the control group (p<0.01); the expression levels of VEGF, IL-10, and SDF-1α were higher than those of the control group (p<0.001), and TNF-α content was lower than the control group (p<0.001). The number of CD34+KDR+ cells was positively correlated with VEGF, IL-10, and TNF-α contents (p<0.01). The results showed that the computer-intelligent segmentation model LT-RCNN could accurately locate, and segment AIS lesions and the early rehabilitation training could change the expression level of inflammatory factors and further promote the mobilization of AIS circulation EPCs.

Posterior reversible encephalopathy syndrome triggered by FLOT (5-fluorouracil, oxaliplatin, docetaxel, and calcium levofolinate) chemotherapy and thrombocytopenia (docetaxel and cisplatin) chemotherapy.

Posterior reversible encephalopathy syndrome is a clinical and imaging syndrome characterized by endothelial dysfunction, blood-brain barrier disruption, and vasogenic edema. The common clinical symptoms of posterior reversible encephalopathy syndrome include headache, altered consciousness, visual disturbances, and seizures, among which headache and seizures are the most common. The classic imaging patterns usually reveal vasogenic edema. We describe the case of a middle-aged woman with gastric cancer. She was under treatment by fluorouracil, leucovorin, oxaliplatin, and docetaxel regimen and thrombocytopenia regimen after tumor progression, but developed unconsciousness, irritability, and headache shortly after initiation of treatment. Her magnetic resonance imaging in our hospital shows abnormal signals in bilateral frontal parietal occipital lobes with hyperintensities on T2-weighted magnetic resonance imaging and fluid-attenuated inversion recovery imaging, accompanied by the increased value of apparent diffusion coefficient. And T1-weighted images illustrate hypointense foci, with increased diffusion-weighted imaging signals. After admission, she was treated to control blood pressure, reduce brain edema, expand blood vessels, improve consciousness, and symptomatic support treatment. 3 days after the onset of the disease, her headache symptoms and state of consciousness gradually improved, and her blood pressure can be controlled at about 130/80 mmHg. This is the first report that posterior reversible encephalopathy syndrome is caused by a thrombocytopenia regimen, and our case highlights the pathogenic role of a thrombocytopenia regimen in posterior reversible encephalopathy syndrome. However, the association between the thrombocytopenia regimen and previous fluorouracil, leucovorin, oxaliplatin, and docetaxel regimens needs further study.

Rare Cortical and Intraparenchymal Epidermoid Cyst within the Right Occipital Lobe (P3-4.004)

<h3>Objective:</h3> N/A <h3>Background:</h3> The differential diagnosis for a diffusion-restricting cortical lesion on brain magnetic resonance imaging (MRI) is broad and includes acute ischemic stroke, abscess, demyelination, Creutzfeldt Jakob disease, encephalitis, and epidermoid cyst. <h3>Design/Methods:</h3> <h3>Case description:</h3> A 13-year-old boy with accelerated growth underwent MRI for pituitary assessment, which incidentally demonstrated a non-enhancing, T2 hyperintense right occipital lesion. No diffusion weighted imaging (DWI) sequences were obtained, and the lesion was suspected to represent encephalomalacia. Five years later, he developed left visual field difficulties and repeat MRI identified right occipital lesional growth with high DWI and low apparent diffusion coefficient (ADC) signal. The patient underwent resection of the right occipital lesion. Histopathology revealed keratin encapsulated by squamous epithelium, consistent with an epidermoid cyst. Our patient is currently doing well, and his left visual field vision is improved. <h3>Results:</h3> <h3>Discussion:</h3> Intracranial epidermoid cysts comprise 1% of primary intracranial tumors and are derived from ectodermal inclusions during neural tube closure. They usually present in middle age due to mass effect on adjacent structures. Epidermoid cysts most commonly occur at the cerebellopontine angle and parasellar region. A cortical location of an intracranial epidermoid cyst, as in our patient’s case, is very rare. The signal intensity of the epidermoid cyst on MRI is variable due to its composition of keratin and lipids and there is usually no associated edema. Total surgical excision is the mainstay of treatment for intracranial epidermoid cysts. Recurrence is not uncommon, but growth is usually slow over many years. <h3>Conclusions:</h3> Neurologists should include intraparenchymal epidermoid cysts in the differential diagnosis for a diffusion restricting lesion on MRI of the brain. <b>Disclosure:</b> Dr. Webb has nothing to disclose. The institution of Dr. Burns has received research support from NIH (NINDS, NCI), DOD, ABTA, Ivy foundation, insightec, Mayo Clinic, Abbvie, . Dr. Zhang has nothing to disclose. Dr. Sener has nothing to disclose.