T2 Signal Intensity Research Articles

Neonatal Brain MRI: Periventricular Germinal Matrix Mimicking Hypoxic-ischemic White Matter Injuries.

As pregnancy progresses, the germinal matrix volume decreases. Residual periventricular germinal matrix may be mistaken for hypoxic-ischemic white matter injury. This study aims to determine the prevalence and imaging characteristics of these findings. This retrospective study analyzed brain MRIs of newborns from 2012-2023, performed within the first week of life. MRIs were done for suspected hypoxic-ischemic injuries, post-natal neurological symptoms, and evaluation of prenatally diagnosed structural anomalies. Image analysis targeted the remnants of the frontal periventricular germinal matrix, assessing its imaging characteristics, including diffusion, T1, and T2 signal characteristics, and laterality. Frontal migrating cell bands were also assessed. Seventy newborns were included (mean gestational age at delivery was 38.3 ± 2.1 weeks, mean scan age 5.1 ± 1.9 days). Frontal periventricular gray matter was detected in 39 newborns (90% bilateral) on T2-weighted images, negatively correlated with gestational age (r = -0.31, p = 0.013); none showed decreased ADC or shortened T1 signal compared with the basal ganglia. Frontal periventricular bands were found in 37 newborns (97.3% bilateral), strongly correlating with periventricular gray matter (r = 0.71, p < 0.001). No correlation was found between clinical hypoxic-ischemic injuries and these features. The presence of frontal periventricular gray matter observed in early neonatal MRIs, without decreased ADC values or shortened T1 signal, is developmental, reflecting a late maturation phase. Careful interpretation of MRI characteristics, including diffusion, T1, and T2 signal intensities, is necessary before attributing these findings to hypoxic-ischemic white matter injury.

Diffusion-Weighted MRI Over Standard MRI for Differential Diagnosis between Mucopyocele and Mucoceles.

To determine the accuracy of conventional and diffusion-weighted (DWI) MRI for the differential diagnosis between mucopyocele and mucocele using surgical diagnosis as a reference. This retrospective study included patients referred to our institution between March 2017 and February 2024 for paranasal sinus MRI to characterize an expansile non-enhanced sinus filling on CT. The T1 and T2 signal intensities were recorded, as well as the presence of restriction diffusion, of the penumbra sign, the double rim sign, and the presence of parietal micro-abscesses. Quantitative apparent diffusion coefficient values were also recorded. The study included 74 patients aged 18 to 88 years (mean age: 60.4 ± 17.7 years). Of these, 43 had a mucopyocele and 31 had a mucocele. The T1 high signal intensity was different amongst groups as an hypersignal was present in 35.5% of mucoceles and only 4.7% of mucopyoceles (p = 0.02). The T2 signal did not differ between the two groups (p = 0.59). The double rim sign and the presence of parietal micro-abscesses demonstrated 96.8% and 100% specificities, respectively, but were predominantly located in the maxillary sinus. The penumbra sign exhibited a sensitivity of 60.5% and a specificity of 67.7%. All mucopyoceles exhibited a diffusion restriction with an apparent diffusion coefficient of less than 0.78 × 10-3 mm2/s. DWI is the most useful MRI tool for the accurate differential diagnosis between mucopyocele and mucocele in non-enhanced sinus fillings. III (case-control study) Laryngoscope, 2024.

Quantitative brain T1 maps derived from T1-weighted MRI acquisitions: a proof-of-concept study.

Longitudinal T1 relaxation time is a key imaging biomarker. In addition, T1 values are modulated by the administration of T1 contrast agents used in patients with tumors and metastases. However, in clinical practice, dedicated T1 mapping sequences are often not included in brain MRI protocols. The aim of this study is to address the absence of dedicated T1 mapping sequences in imaging protocol by deriving T1 maps from standard T1-weighted sequences. A phantom, composed of 144 solutions of paramagnetic agents at different concentrations, was imaged with a three-dimensional (3D) T1-weighed turbo spin-echo (TSE) sequence designed for brain imaging. The relationship between the T1 values and the signal intensities was established using this phantom acquisition. T1 mapping derived from 3D T1-weighted TSE acquisitions in four healthy volunteers and one patient with brain metastases were established and compared to reference T1 mapping technique. The concentration of Gd-based contrast agents in brain metastases were assessed from the derived T1 maps. Based on the phantom acquisition, the relationship between T1 values and signal intensity (SI) was found equal to T1 = 0.35 × SI-1.11 (R2 = 0.97). TSE-derived T1 values measured in white matter and gray matter in healthy volunteers were equal to 0.997 ± 0.096 s and 1.358 ± 0.056 s (mean ± standard deviation), respectively. Mean Gd3+ concentration value in brain metastases was 94.7 ± 30.0 μM. The in vivo results support the relevance of the phantom-based approach: brain T1 maps can be derived from T1-weighted acquisitions. High-resolution brain T1 maps can be generated, and contrast agent concentration can be quantified and imaged in brain metastases using routine 3D T1-weighted TSE acquisitions. Quantitative T1 mapping adds significant value to MRI diagnostics. T1 measurement sequences are rarely included in routine protocols. T1 mapping and concentration of contrast agents can be derived from routine standard scans. The diagnostic value of MRI can be improved without additional scan time.

Multiparameter magnetic resonance imaging features of prostatic malakoplakia.

To summarize the multiparameter magnetic resonance imaging (mpMRI) features of prostatic malakoplakia. Eleven patients (median age 62 years; IQR 59-71 years) with pathologically confirmed prostatic malakoplakia were included in this study. MpMRI features of the lesions were retrospectively reviewed and summarized. The Prostate Imaging-Reporting and Data System (PI-RADS) scores of the patients were 4 or 5, with a medium diameter of 3.7 cm (IQR 2.0-5.2 cm). All the lesions involved the peripheral zone, of which 3 cases (3/11, 27.3%) involved the transition zone simultaneously. A diffuse symmetrical distribution was found in 5 cases, a focal distribution in 5 cases, and a focal symmetrical distribution in 1 case. Both the surgical capsule and prostatic margin were bulged and compressed, but no signs of infiltration were found. Nearly all the lesions had moderate hypointensity on T2-weighted images and slightly higher signal intensity on T1-weighted images. Among the lesions, early enhancement occurred in all cases, prolonged enhancement occurred in 8 cases, and ring enhancement persisted in 1 case. All lesions displayed periprostatic enhancement in the delayed phase. Lesions distributed diffusely and symmetrically in the peripheral zone with preserved surgical capsule and margin are characteristic features of malakoplakia as opposed to cancer, especially in those with slightly high T1 signal intensity and delayed periprostatic enhancement. Those locally distributed lesions with the above signs should also be suspected. Prostatic malakoplakia are more likely to distribute diffusely and symmetrically, with slightly high T1 signal intensity and delayed periprostatic enhancement.

Factors affecting the technical outcome of catheter-directed sclerotherapy for ovarian endometriomas

PurposeTo identify factors related to technical outcomes of catheter-directed sclerotherapy (CDS) and suggest selection criteria for CDS in patients with ovarian endometrioma. MethodThis retrospective study included patients with endometriomas treated with CDS between November 2015 and June 2023. The characteristics of the endometriomas, including diameter, morphology (unilocular or multilocular), and T2 signal intensity were evaluated using pre-procedure magnetic resonance imaging. Moreover, the size of the catheter (7- or 8.5-French) and route of access (transabdominal vs. transvaginal) was also analyzed. Multivariate logistic regression analyses were used to identify factors associated with the technical outcomes of CDS. ResultsTechnical success was defined as successful completion of the following: 1) insertion of a 7- or 8.5-French catheter into the endometrioma, 2) full aspiration of the internal content, and 3) completion of sclerotherapy without ethanol leakage. Of the 323 women (mean age = 32.2 ± 6.0 years) with 401 endometriomas included in our study, technical success was achieved in 377 endometriomas (94.0 %). No major complications were observed. In the multivariate analysis, a diameter < 3 cm (odds ratio, 25.641; p < 0.001), T2 dark signal intensity (odds ratio, 7.462; p = 0.001), and transvaginal access (odds ratio, 4.016; p = 0.004) were associated with technical failure. ConclusionsSmall endometrioma size (<3cm), T2 dark signal intensity, and transvaginal access were identified as significant risk factors for technical failure during catheter-directed sclerotherapy.

Neuroimaging feature in identifying acute myelopathy etiologies: comparison between neuromyelitis optica spectrum disorder and cervical spondylotic myelopathy

ObjectiveThe clinical symptoms of neuromyelitis optica spectrum disorder (NMOSD) and acute cervical spondylotic myelopathy (CSM) may overlap in some cases. This study aimed to investigate the differences in imaging features between NMOSD and CSM in acute myelopathy.MethodsWe included 78 patients in this retrospective study, including 28 NMOSD patients and 50 CSM patients. The demographic characteristics and clinical symptoms of the two groups of patients were compared. The T1 signal intensity, length of the spinal cord involved by T2 hyperintensity, degree of intervertebral disc degeneration, proportion of thoracic and lumbar cord involvement, proportion of brain involvement and lesion enhancement rate in magnetic resonance imaging (MRI) were compared between the two groups of patients. The number, length, location on the sagittal image, pattern on the sagittal image, and distribution on the axial image of the lesions in the contrast-enhanced MRI of the two groups were evaluated.ResultsThere were differences between NMOSD and CSM patients in the proportion of women, the proportion of bowel and bladder symptoms, mRS levels, the length of the spinal cord involved by T2 hyperintensity, degree of intervertebral disc degeneration, the proportion of thoracic and lumbar cord involvement, the proportion of brain involvement, the enhancement rate and number of lesions (p < 0.05). Among NMOSD patients, linear, patchy and ring or semi-ring enhancement were present in 8(30.8%) ,14 (53.8%) and 4(15.4%)patients, respectively, and axial gray and white matter were involved in 17 (65.4%) patients. Among patients with CSM, 9(36.0%) patients showed longitudinal oriented flake, 16 (64.0%) patients showed pancake-like enhancement, and 21 (84.0%) patients showed axial white matter involvement only. The differences in enhancement pattern on sagittal images and axial involvement were statistically significant (p < 0.05).ConclusionsEarly differential diagnosis of NMOSD and CSM in acute myelopathy can be made by analyzing images and the number, length, sagittal enhancement pattern, and axial involvement of gadolinium-enhanced lesions.

Clinical Problem-Solving: A 19-Year-Old Woman With Progressive Neurological Decline and Multiple Intracranial Lesions.

The differential diagnosis for multiple intracranial lesions in a young adult is broad and includes demyelinating, neoplastic, and infectious etiologies. In this report, we describe the case of a 19-year-old immunocompetent woman presenting with progressive headaches and aphasia. MRI of the brain revealed multiple, large supratentorial lesions with concentric bands of alternating T2 signal intensities and peripheral contrast enhancement. Cerebrospinal fluid (CSF) analysis was overall bland with negative oligoclonal bands. Serum antibody testing for neuromyelitis optica (NMO) and myelin-oligodendrocyte associated disease (MOGAD) were negative. A broad infectious work-up was also unrevealing. A definitive diagnosis was ultimately obtained after brain biopsy and the patient was started on appropriate therapy. This case highlights a diagnostic framework in evaluating immunocompetent patients presenting with multiple intracranial lesions and progressive neurological decline. The main differential diagnoses for this constellation of radiological and clinical findings are discussed and a literature review is performed on the revealed diagnosis. Lastly, both acute and long-term therapeutic approaches are reviewed.

Utility of Sonoelastography and Magnetic Resonance Imaging in Characterization of Thyroid Nodules.

To evaluate thyroid nodules with sonoelastography and magnetic resonance imaging (MRI). The study included 28 patients with 40 thyroid nodules. Clearance was obtained from the institute's ethical clearance committee. Patients with pure cystic nodules or nodules with eggshell calcification, diffuse thyroid pathology (such as Graves' disease, Hashimoto's thyroiditis, De Quervain thyroiditis, and Riedel's thyroiditis), inaccessible nodules via fine needle aspiration cytology (FNAC), or patients with a history of thyroid gland surgery were excluded from the study. Strain elastography was performed on a Phillips iU22 machine, producing qualitative color-coded strain maps (graded using the Rago 5-point system) and semiquantitative strain ratios. MRI was performed on a Phillips ACHIEVA 1.5T magnet with a head and neck coil. Rago scores statistically correlated (χ2 = 18.052, p < 0.001) with malignant nodules, and using the receiver operating characteristic (ROC) curve, the area under the ROC curve (AUROC) for the mean strain ratio predicting malignant outcomes was 0.88 [95% confidence interval (CI): 0.767-0.992], which was also statistically significant (p < 0.001). A cutoff of mean strain ratio ≥2.48 predicted malignant outcomes with 100% specificity. T2 signal intensity ratio (SIR) and apparent diffusion coefficient (ADC) values were not statistically significant in predicting malignant outcomes. Kinetic curves were statistically significant for Rago scores (χ2 = 11.356, p = 0.045); however, no significant difference was found in predicting malignant outcomes. We concluded that sonoelastography, along with grayscale ultrasound, is a useful noninvasive technique for predicting histological outcomes. However, MRI should largely be reserved as a problem-solving tool rather than a standalone imaging modality. The kinetic curves show some degree of overlap between histologically distinct diseases, and thus large-scale multicenter trials are needed for further standardization.

T1 signal intensity ratio correlation with T1 mapping in pediatric pancreatitis.

Our primary purpose was to understand the correlation between pancreas T1-weighted signal intensity ratio (SIR) and T1 relaxation time in children. We also sought to characterize differences in T1 SIR between children without and with pancreatitis. Retrospective study of patients < 18-years-old. SIR-pancreas:spleen (SIR-PS) and SIR-pancreas:paraspinal muscle (SIR-PM) were generated from T1-weighted gradient recalled echo images. Subdivided by field strength, T1 SIR was correlated (Spearman's) with T1 relaxation time. 220 participants were included, 144 imaged at 1.5T (mean: 11.4 ± 4.2 years) and 76 imaged at 3T (mean: 10.9 ± 4.5 years). At 1.5T, SIR-PS (rho=-0.62, 95% CI: -0.71 to -0.51, p < 0.0001) and SIR-PM(rho=-0.57, 95% CI: -0.67 to -0.45, p < 0.0001) moderately negatively correlated with T1 relaxation time. At 3T, correlations between T1 SIR and T1 relaxation time were moderate (rho=-0.40 to -0.43, p ≤ 0.0003). SIR-PS was significantly different between patient groups at 1.5T (p < 0.0001) with pairwise differences between: normal vs. acute on chronic pancreatitis (1.52 vs. 1.13; p < 0.0001). SIR-PM was also significantly different between groups at 1.5T (p < 0.0001) with differences between: normal vs. acute pancreatitis (1.65 vs. 1.40; p = 0.0006), normal vs. acute on chronic pancreatitis (1.65 vs. 1.18; p < 0.0001), and normal vs. chronic pancreatitis (1.65 vs. 1.52; p = 0.0066). A SIR-PS cut-off of ≤ 1.31 had 44% sensitivity and 95% specificity and SIR-PM cut-off of ≤ 1.53 had 69% sensitivity and 70% specificity for pancreatitis. At 3T, SIR-PS was significantly different between groups (p = 0.033) but without significant pairwise differences. At 1.5T pancreas T1 SIR moderately to strongly correlates with estimated T1 relaxation time and is significantly lower in children with pancreatitis.

Magnetic resonance imaging signal changes at the intramuscular injection site in dogs: Comparison of medetomidine and saline.

Intramuscular administration is a commonly used method for delivering sedatives and anesthetics in veterinary medicine. Previous studies have reported inflammation at the intramuscular injection site in laboratory animals and observed signal changes on MRI following intramuscular injections in humans. We hypothesized that following intramuscular injection, the site would exhibit T2 hyperintensity and contrast enhancement on MRI. To investigate this, this prospective study evaluated the pattern of signal changes and grade of T2 signal intensity and contrast enhancement over time after the intramuscular injection of medetomidine at a premedication dosage, comparing it to saline. MRI scans were performed immediately postinjection into the biceps femoris and quadriceps femoris muscles, as well as at 2, 8, 24, and 72h, and 7 days postinjection. A semiquantitative scale was utilized to grade signal intensity and contrast enhancement. Both medetomidine and saline injections showed T2 hyperintensity immediately after injection and contrast enhancement from 2h postinjection, manifesting as flame-shaped. These signal changes decreased up to 24h postinjection (p<.05). The signal changes induced by medetomidine showed higher T2 hyperintense change and stronger contrast enhancement compared with saline at most time points, with the signal changes persisting for a longer duration (p<.05). These findings suggest that intramuscular administration of medetomidine induces a more severe tissue reaction compared with saline, and the results are expected to aid in the differentiation of various muscle diseases that present with similar MRI findings.

Hypothalamic Gliosis is Associated With Multiple Cardiovascular Disease Risk Factors.

Hypothalamic gliosis is mechanistically linked to obesity and insulin resistance in rodent models. We tested cross-sectional associations between radiologic measures of hypothalamic gliosis in humans and clinically relevant cardiovascular disease risk factors, as well as prevalent coronary heart disease. Using brain MRI images from Framingham Heart Study participants (N=867; mean age, 55 years; 55% females), T2 signal intensities were extracted bilaterally from the region of interest in the mediobasal hypothalamus (MBH) and reference regions in the amygdala (AMY) and putamen (PUT). T2 signal ratios were created in which greater relative T2 signal intensity suggests gliosis. The primary measure compared MBH to AMY (MBH/AMY); a positive control ratio (MBH/PUT) also assessed MBH whereas a negative control (PUT/AMY) did not. Outcomes were BMI, HDL-C, LDL-C, fasting triglycerides, and the presence of hypertension (n=449), diabetes mellitus (n=66), metabolic syndrome (n=254), or coronary heart disease (n=25). Dietary risk factors for gliosis were assessed in a prospective analysis. Statistical testing was performed using linear or logistic regression. Greater MBH/AMY T2 signal ratios were associated with higher BMI (β = 21.5 [95% CI, 15.4-27.6]; P<0.001), higher fasting triglycerides (β = 1.1 [95% CI, 0.6-1.7]; P<0.001), lower HDL-C (β = -20.8 [95% CI, -40.0 to -1.6]; P=0.034), and presence of hypertension (odds ratio, 1.2 [95% CI, 1.1-1.4]; P=0.0088), and the latter two were independent of BMI. Findings for diabetes mellitus were mixed and attenuated by adjusting for BMI. Metabolic syndrome was associated with MBH/AMY T2 signal ratios (odds ratio, 1.3 [95% CI, 1.1-1.6]; P<0.001). Model results were almost uniformly confirmed by the positive control ratios, whereas negative control ratios that did not test the MBH were unrelated to any outcomes (all P≥0.05). T2 signal ratios were not associated with prevalent coronary heart disease (all P>0.05), but confidence intervals were wide. Self-reported percentages of macronutrient intake were not consistently related to future T2 signal ratios. Using a well-established study of cardiovascular disease development, we found evidence linking hypothalamic gliosis to multiple cardiovascular disease risk factors, even independent of adiposity. Our results highlight the need to consider neurologic mechanisms to understand and improve cardiometabolic health.

An unusual cause of liver neoplasm in an older female.

We presented a 66-year-old woman with T2DM who had a liver mass discovered incidentally during hospitalization. She was asymptomatic with a right upper abdominal mass that was smooth, mobile, and non-tender. Hepatitis virus markers and tumor markers were normal. The computed tomography (CT) images showed a 4.7×4.0 cm lesion in the left liver lobe with indistinct borders. Further magnetic resonance imaging (MRI) revealed low T1 and high T2 signal intensity with ring-shaped enhancement following contrast administration. Surgical resection was performed, and histology confirmed hepatic angioleiomyoma with thick-walled vessels and spindle cell proliferation. Immunohistochemistry was positive for SMA, desmin, caldesmon, CD31, and CD34. The patient had no recurrence during 5 years follow-up.

Multiparametric MRI Scoring System of the Pancreas for the Diagnosis of Chronic Pancreatitis.

Ductal features alone may not offer high diagnostic sensitivity or most accurate disease severity of chronic pancreatitis (CP). Diagnose CP based on multiparametric MRI and MRCP features. Prospective. Between February 2019 and May 2021, 46 control (23 males, 49.3 ± 14.1 years), 45 suspected (20 males, 48.7 ± 12.5 years), and 46 definite (20 males, 53.7 ± 14.6 years) CP patients were enrolled at seven hospitals enrolled in the MINIMAP study. CP classification was based on imaging findings and clinical presentation. 1.5 T. T1-weighted (T1W) spoiled gradient echo, T1 map with variable flip angle, dual-echo Dixon, secretin-enhanced MRCP before and after secretin infusion. Dual-echo fat fraction (FF), T1 relaxation time, extracellular volume (ECV), T1 signal intensity ratio of the pancreas to the spleen (T1 score), arterial-to-venous enhancement ratio (AVR), pancreatic tail diameter (PTD), pancreas volume, late gadolinium enhancement, pancreatic ductal elasticity (PDE), and duodenal filling grade of secretin-enhanced MRCP were measured. Logistic regression analysis generated CP-MRI and secretin-enhanced CP-SMRI scores. Receiver operating characteristics analysis was used to differentiate definite CP from control. Interobserver agreement was assessed using Lin's concordance correlation coefficient. Compared to control, definite CP cohort showed significantly higher dual-echo FF (7% vs. 11%), lower AVR (1.35 vs. 0.85), smaller PTD (2.5 cm vs. 1.95 cm), higher ECV (28% vs. 38%), and higher incidence of PDE loss (6.5% vs. 50%). With the cut-off of >2.5 CP-MRI score (dual-echo FF, AVR, and PTD) and CP-SMRI score (dual-echo FF, AVR, PTD, and PDE) had cross-validated area under the curves of 0.84 (sensitivity 87%, specificity 68%) and 0.86 (sensitivity 89%, specificity 67%), respectively. Interobserver agreement for both CP-MRI and CP-SMRI scores was 0.74. The CP-MRI and CP-SMRI scores yielded acceptable performance and interobserver agreement for the diagnosis of CP. 1 TECHNICAL EFFICACY: Stage 2.

Application of proton density fat fraction imaging in risk stratification of prostate cancer.

Prostate cancer (PCa) as one of the most prevalent malignancies in men. We introduced a non-invasive quantitative measurement of intraprostatic fat content based on magnetic resonance proton density fat fraction (PDFF) imaging. The study aims to determine the fat fraction (FF) of PCa using proton density magnetic resonance imaging (MRI), gather clinical and routine MRI characteristics, and identify risk factors for high-risk PCa through multifactorial logistic regression. Clinical and imaging data from 191 pathologically confirmed PCa patients were collected. Patients were stratified based on Gleason score (GS), with 63 in the intermediate- and low-risk group (GS =3+3, 3+4) and 128 in the high-risk group (GS ≥4+3). All patients underwent routine prostate MRI and FF imaging. Clinical and imaging data related to PCa were analyzed, including age, body mass index (BMI), prostate volume (PV) measured by MRI, smoking history, alcohol history, diabetes history, serum prostate-specific antigen (PSA) level, apparent diffusion coefficient (ADC) value, T2 signal intensity (T2SI), Prostate Imaging Reporting and Data System 2.1 (PI-RADS 2.1) score, GS, lesion FF, whole gland FF, periprostatic fat thickness (PPFT), and subcutaneous fat thickness (SFT). Independent risk factors for stratifying PCa risk were identified through multivariate logistic regression analysis, and a predictive model was established. Receiver operating characteristic (ROC) curve analysis was conducted for visual analysis. Significant differences were found in BMI, PV, PSA, tumor ADC value, standard T2SI, PI-RADS score, lesion FF, and PPFT between low- and medium-risk and high-risk groups (P<0.05). No significant differences were observed in age, smoking history, drinking history, diabetes history, and SFT between the two groups (P>0.05). GS correlated significantly with FF (ρ=0.6, P<0.001), PSA (ρ=0.432, P<0.001), ADC value (ρ=-0.379, P<0.001), and PI-RADS (ρ=0.366, P<0.001). Multiple logistic regression analysis revealed that an increase in FF, a PI-RADS score increase of 5 points, and a decrease in ADC value and PV were independent predictors of high-risk PCa (P<0.05). The ROC curve showed that the best cut-off value for the model was 0.67, with an area under the curve (AUC) of 0.907, sensitivity of 78.1%, and specificity of 88.9%. The FF of PCa determined by proton density MRI is significantly associated with GS, serving as an independent predictor of high-risk PCa.

Atlantoaxial intra-articular cage fusion by posterior intermuscular approach for treating reducible atlantoaxial dislocation: a technique note with case series.

To evaluate the clinical feasibility of atlantoaxial intra-articular cage (AIC) fusion via intermuscular approach for treating reducible atlantoaxial dislocation (AAD). An analysis was conducted on the data of 10 patients who underwent C1-C2 segmental fixation and AIC fusion for AAD by unilateral intermuscular approach and contralateral open approach. Outcome assessments included Japanese Orthopaedic Association score (JOA) and Visual Analog Scale Score for Neck Pain (VASSNP). The duration of surgical exposure, screw insertion and cage insertion, and postoperative drainage volume were also compared between two approaches. Bone fusion was evaluated through computed tomography (CT) reconstruction. Postoperative paravertebral tissue edema was evaluated by paravertebral tissue cross-sectional area (CSA) and signal intensity on T2 weighted sequence of magnetic resonance imaging (MRI) at 3 days postoperatively. The intermuscular approach exhibited a longer exposure time but lower drainage postoperatively compared to the open approach (P < 0.05). After operation, JOA scores significant improved (P < 0.05), while VASSNP scores significantly decreased (P < 0.05). There was no significant difference in preoperative CSA between two approaches (P > 0.05). However, compared to the open approach, the intermuscular approach exhibited less CSA (P < 0.05) and lower T2 signal intensity on MRI postoperatively, indicating less invasive to the paravertebral tissues. AIC fusion by intermuscular approach is an effective and safe technique in the treatment of reducible AAD. Intermuscular approach could reduce the postoperative drainage volume and the extent of paravertebral tissue edema compared to open approach.

Study on the damage mechanism and evolution model of preloaded sandstone subjected to freezing–thawing action based on the NMR technology

Abstract Investigating the damage degradation of rock during the freezing and thawing process is more consistent with the actual engineering environment, considering its internal initial damage. In this study, the effects of initial damage from preloading and subzero-temperature freezing–thawing on microscopic and macroscopic mechanical properties of sandstone were studied based on the nuclear magnetic resonance (NMR) technique. The results show that the P-wave velocity of the sample decreased, while the porosity increased as the initial damage level increased. The distribution of T2 signal intensity exposed to the low-temperature freezing–thawing–saturation treatment was rather larger than that under normal temperature conditions for samples with different levels of initial damage from preloading, indicating that the low-temperature freezing–thawing condition would promote the porosity and have an obvious increase in damage. A continuum damage model considering subzero-temperature freezing–thawing damage from different pore sizes was finally introduced to describe the damage evolution mechanism of sandstone. The research results can be used to quantitatively evaluate the damage evolution mechanism of sandstone treated by subzero-temperature freezing–thawing without mechanical tests. Furthermore, the analysis and research results show that the damage variables of sandstone obtained by the NMR theory were lower than those of classical rock mechanics theory.

Pediatric diffuse intrinsic pontine glioma radiotherapy response prediction: MRI morphology and T2 intensity-based quantitative analyses.

An easy-to-implement MRI model for predicting partial response (PR) postradiotherapy for diffuse intrinsic pontine glioma (DIPG) is lacking. Utilizing quantitative T2 signal intensity and introducing a visual evaluation method based on T2 signal intensity heterogeneity, and compared MRI radiomic models for predicting radiotherapy response in pediatric patients with DIPG. We retrospectively included patients with brainstem gliomas aged ≤ 18 years admitted between July 2011 and March 2023. Applying Response Assessment in Pediatric Neuro-Oncology criteria, we categorized patients into PR and non-PR groups. For qualitative analysis, tumor heterogeneity vision was classified into four grades based on T2-weighted images. Quantitative analysis included the relative T2 signal intensity ratio (rT2SR), extra pons volume ratio, and tumor ring-enhancement volume. Radiomic features were extracted from T2-weighted and T1-enhanced images of volumes of interest. Univariate analysis was used to identify independent variables related to PR. Multivariate logistic regression was performed using significant variables (p < 0.05) from univariate analysis. Of 140 patients (training n = 109, and test n = 31), 64 (45.7%) achieved PR. The AUC of the predictive model with extrapontine volume ratio, rT2SRmax-min (rT2SRdif), and grade was 0.89. The AUCs of the T2-weighted and T1WI-enhanced models with radiomic signatures were 0.84 and 0.81, respectively. For the 31 DIPG test sets, the AUCs were 0.91, 0.83, and 0.81, for the models incorporating the quantitative features, radiomic model (T2-weighted images, and T1W1-enhanced images), respectively. Combining T2-weighted quantification with qualitative and extrapontine volume ratios reliably predicted pediatric DIPG radiotherapy response. Combining T2-weighted quantification with qualitative and extrapontine volume ratios can accurately predict diffuse intrinsic pontine glioma (DIPG) radiotherapy response, which may facilitate personalized treatment and prognostic assessment for patients with DIPG. Early identification is crucial for radiotherapy response and risk stratification in diffuse intrinsic pontine glioma. The model using tumor heterogeneity and quantitative T2 signal metrics achieved an AUC of 0.91. Using a combination of parameters can effectively predict radiotherapy response in this population.

IMG-21. HOW CAN WE BEST UTILISE HISTORICAL IMAGING DATASETS FOR RESEARCH IN PAEDIATRIC NEURO-ONCOLOGY? A REVIEW OF HISTORICAL PRE-OPERATIVE IMAGING PERFORMED FOR 92 PAEDIATRIC BRAIN TUMOUR PATIENTS WITH COMPARISON TO 2021 SIOPE GUIDELINES

Abstract BACKGROUND Utilisation of historical imaging is important for studying long-term outcomes in paediatric brain tumours often pooling data across multiple centres retrospectively over many years. Disparities in MRI sequence parameters, imaging planes, fields of view and resolution limit quantitative radiomic analysis and segmentation algorithms. We review historical imaging datasets, analysing the MRI scans performed assessing suitability for modern research techniques. METHODS Retrospective review of presenting MRI scans was performed in 92 paediatric brain tumour patients between 2006-2020. Whether imaging was performed internally at our paediatric neurosciences centre or externally at their referring hospitals was recorded. Image sequences, planes and slice thickness were compared with 2021 SIOPE guidelines for paediatric brain tumour imaging. T2 signal intensities for tumour, white and grey matter were compared for scans completed in different centres. Statistical testing was performed with T-Test and Paired T-Test. RESULTS 75% of patients had all SIOPE essential sequences and 60.9% were in the recommended planes. Only 1 patient had the desired slice thickness in all sequences recommended for 1.5T scanners. 38.5% had T1 and 27.8% had post-contrast T1 in the ≤1mm slice thickness recommended for 3T scanners. Comparison between 62 internal and 30 external scans revealed statistically significant differences in T2 signal intensities for regions of interest (ROI) within tumour, white and grey matter (p&amp;lt;0.01). Comparison of matched ROI for 12 patients imaged internally and externally demonstrated statistically significant differences in T2 signal intensities (p&amp;lt;0.05). Differences persisted despite normalisation of T2 signal intensity as ratios between tumour and the weighted mean of white and grey matter (p&amp;lt;0.01). CONCLUSIONS This study highlights the challenges of non-standardisation of imaging resolution and acquisition parameters in historical imaging. One approach to utilise these datasets is to use qualitative classifications where human experts label imaging features and encode data for future statistical or machine learning analysis.

Optic Nerve T2 Signal Intensity and Caliber Reflect Clinical Severity in Genetic Optic Atrophy.

Genetic optic atrophies comprise phenotypically heterogenous disorders of mitochondrial function. We aimed to correlate quantitative neuroimaging findings of the optic nerves in these disorders with clinical measures. From a retrospective database of 111 patients with bilateral optic atrophy referred for genetic testing, 15 patients diagnosed with nonglaucomatous optic atrophy of genetic origin (7 patients with pathogenic variants in OPA1, 3 patients with Wolfram syndrome, and 5 patients with Leber hereditary optic neuropathy) who had accessible magnetic resonance (MR) images of the orbits and/or brain were analyzed. The primary outcome measures of T2 short Tau inversion recovery (STIR) signal and optic nerve caliber were quantified according to a standardized protocol, normalized to internal standards, and compared between cases and controls. Inter-rater reliability was assessed and clinical features were analyzed according to MRI features. Compared with control patients, the 15 genetic optic atrophy patients demonstrated significantly increased T2 STIR signal (fold-change 1.6, P = 0.0016) and decreased optic nerve caliber (fold-change 0.72, P = 0.00012) after internal normalization. These metrics were reliable (inter-reader reliability correlation coefficients of 0.98 [P = 0.00036] and 0.74 [P = 0.0025] for normalized STIR and nerve caliber, respectively) and significantly correlated with visual acuity, cup-to-disc ratio, and visual field testing. Normalized optic nerve STIR signal and optic nerve caliber significantly correlate with visual acuity, cup-to-disc ratio, and perimetric performance in patients with genetic optic atrophy. A formalized protocol to characterize these differences on MRI may help to guide accurate and expedient diagnostic evaluation.

Torticollis and right arm weakness due to atraumatic spinal epidural hematoma in a 5-year-old girl child

Spontaneous spinal epidural hematoma (SEH) is a rare presentation as cause of neurological weakness in children and is neurological emergency. The most commonly affected site in children is cardiothoracic region. Early management is associated with better functional outcomes. We report a 5-year-old girl who presented with long standing neck pain now presenting to emergency with torticollis and right arm weakness around shoulder joint. Magnetic resonance imaging of C-spine revealed posterior epidural hematoma that extend from C3/C4 level down to C6/C7 level, it is causing moderate spinal canal stenosis and mass-effect on the spinal cord, with mild intramedullary abnormal T2 signal intensity indicating myelomalacia. There were no predisposing factors in our patient. Epidural hematoma was drained surgically and post-surgery patient started showing neurological recovery on follow. Cases of spontaneous SEH have been reported in infants as well and the clinical features in children are often nonspecific leading to a delay in diagnosis. This case report aims to raise awareness about this neurological emergency, in which early intervention is crucial.