Imaging Time Research Articles

Unsupervised Learning for Enhanced Computed Photoacoustic Microscopy

Photoacoustic microscopy (PAM) is a medical-imaging technique with the merits of high contrast and resolution. Nevertheless, conventional PAM scans specimens in a diameter-by-diameter fashion, resulting in a time-consuming process. Furthermore, deep-learning-based PAM image enhancement necessitates acquiring ground-truth data for training purposes. In this paper, we built an optical-resolution photoacoustic microscopy system and introduced an innovative unsupervised-learning algorithm. First, we enhanced the rotational-scanning method, transitioning from a diameter-by-diameter approach to a sector-by-sector one, significantly reducing imaging time (from 280 s to 109 s). Second, by establishing a metric for unsupervised learning, we eliminated the need for collecting reliable and high-quality ground truth, which is a challenging task in photoacoustic microscopy. A total of 324 pairs of datasets (mouse ears) were collected for unsupervised learning, with 274 for training and 50 for testing. Additionally, carbon-fiber data were sampled for lateral resolution and contrast evaluation, as well as the effective rate evaluation of the algorithm. The enhanced images demonstrated superior performance compared with that of maximum projection, both subjectively and objectively. A 76% improvement in the lateral resolution was observed. The effective rate of the algorithm was measured to be 100%, which was tested on 50 random samples. The technique presented in this paper holds substantial potential for image postprocessing and opens new avenues for unsupervised learning in photoacoustic microscopy.

Prediction of [177Lu]Lu-DOTA-TATE therapy response using the absorbed dose estimated from [177Lu]Lu-DOTA-TATE SPECT/CT in patients with metastatic neuroendocrine tumour.

Peptide receptor radionuclide therapy (PRRT) with [177Lu]Lu-DOTA-TATE has shown efficacy in patients with metastatic neuroendocrine tumours (NETs). Personalised dosimetry is crucial to optimise treatment outcomes and minimise adverse events. In this study, we investigated the correlation between the tumour-absorbed dose (TAD) estimated from [177Lu]Lu-DOTA-TATE SPECT/CT and the therapeutic response. A retrospective analysis was conducted on patients with advanced well-differentiated NETs grades 1-3 who underwent PRRT and exhibited greater uptake than liver on pre-therapeutic [68Ga]Ga-DOTA-TOC PET/CT. Target lesions were selected based on the RECIST 1.1 and PERCIST 1.0 criteria using [177Lu]Lu-DOTA-TATE SPECT/CT and pre-therapeutic contrast-enhanced CT scans. For anatomical image analysis, the sum of the longest diameter (SLD) of the target lesions was measured using the RECIST 1.1 criteria for patient-based analysis and the longest diameter (LD) of the target lesion using the RECIST-L criteria for lesion-based analysis. Standardised uptake values (SUVs) were measured on SPECT/CT images, and TADs were calculated based on the SUVs. Dosimetry was performed using a single SPECT/CT imaging time point at day 4-5 post-therapy. Statistical analyses were conducted to investigate correlations and determine the target lesion responses. Twenty patients with primary tumour sites and hepatic metastases were included. Fifty-five target lesions, predominantly located in the pancreas and liver, were analysed. The cumulative TAD (lesion-based analysis: r = 0.299-0.301, p = 0.025-0.027), but not the cycle 1 SUV (lesion-based analysis: r = 0.198-0.206, p = 0.131-0.147) or cycle 1 TAD (lesion-based analysis: r = 0.209-0.217, p = 0.112-0.126), exhibited a significant correlation with the change in LD of the target lesion. Binary logistic regression analysis identified the significance of the cumulative TAD in predicting disease control according to the RECIST-L criteria (odds ratio = 1.031-1.051, p = 0.024-0.026). The cumulative TAD estimated from [177Lu]Lu-DOTA-TATE SPECT/CT revealed a significant correlation with change in LD, which was significantly higher for the cumulative TAD than for the cycle 1 SUV or TAD. A higher cumulative TAD was associated with disease control in the target lesion. However, considering the limitations inherent to a confined sample size, careful interpretation of these findings is required. Estimation of the cumulative TAD of [177Lu]Lu-DOTA-TATE therapy could guide the platform towards personalised therapy.

Abstract WMP13: The Modifying Effects of Psychosocial Health on the Association Between Cerebrovascular Health and Dementia Risk: The Atherosclerosis Risk in Communities (ARIC) Neurocognitive Study

Introduction: Associations between magnetic resonance imaging (MRI) markers of vascular pathology and dementia risk in older adults have been established, but it remains less clear how lifestyle factors may modify this association. We hypothesized that a weaker association between MRI markers of vascular pathology and incident dementia will be present among older adults with strong as compared to poor psychosocial health in mid-life. Methods: Social support and social isolation were assessed among ARIC participants, aged 46 - 68, via self-reported questionnaires (1990 - 1992). Following categorization of both factors, participants were classified as having strong or poor mid-life psychosocial health. From 2011 - 2013, 1977 participants, aged 67 - 90, underwent 3T brain MRI quantifying white matter hyperintensity (WMH) volume, subcortical cerebral microbleeds (sCMB), infarcts, and white matter integrity through diffusion tensor imaging. Incident dementia cases were identified from time of imaging through December 31, 2019 (median follow-up: 6.4 years) with ongoing surveillance. Relative contributions of psychosocial health and MRI markers to incident dementia were evaluated with demographic and vascular risk factor-adjusted Cox-proportional hazard regression models. Results: Among 1612 dementia-free participants with measures of psychosocial health, MRI markers were associated with dementia risk in the hypothesized direction. Mid-life psychosocial health significantly modified the associations between sCMB and WMH, each, with incident dementia risk (Table 1; greater risk of dementia shown in individuals with poor psychosocial health). Conclusions: The elevated risk of dementia associated with sCMB and WMH is reduced in participants with strong psychosocial health in mid-life. Future studies evaluating social factors through the life course and the mechanisms by which they modify the relationship between pathology and dementia are needed.

Abstract TP171: Nationwide Diurnal Pattern Among Intracerebral Hemorrhage Incidence and Volume

Introduction: Intracerebral hemorrhage (ICH) incidence follows both seasonal and diurnal patterns noted in the literature. These differences have been attributed to variations in the coagulation cascade, blood pressure, and sleep-wake cycle that all have their own noted rhythmicity. The purpose of this analysis was to validate these trends in a large nationwide database of automated ICH detection scans and evaluate for differences in hematoma volume by image acquisition time. Methods: Serial non-contrast head CT (NCHCT) data, processed with an automated imaging software (iSchemaView), was acquired from U.S. hospitals between 1/1/2020 and 12/31/2021. Final exclusion criteria included: (1) patient age ≤ 25, (2) hematoma volume ≥ 100 ml, (3) hematoma volume ≤ 0.4 ml. Imaging time was subdivided into three epochs: (1) Night: 23:00h-06:59h, (2) Day: 07:00h-14:59h, and (3) Evening: 15:00h-22:59h. Results: A total of 19,397 scans were included in the final analysis with a median ICH volume of 2.9 ml; 15.6% of these scans had volumes above 30 ml. Peak imaging occurred around noon. Hematoma volume was significantly different across timepoints (p = 0.003), with ICHs presenting at night (average volume 14.2 ml) larger than those presenting during the day (12.9 ml, p = 0.002) or evening (13.0 ml, p = 0.012). Conclusion: In this real world, multi-site data set, we show similar diurnal trends in ICH incidence and can detect subtle differences in volume based on time of imaging. Further research is required to elucidate the potential underlying mechanisms for these differences.

Utility of PSMA PET/CT for imaging ductal carcinoma of the prostate.

49 Background: Ductal carcinoma (DC) is the second most commonly encountered histologic variant of prostate cancer. Previous studies have described its molecular features and aggressive behavior, but few have explored the performance of PSMA PET/CT in the initial staging and follow-up of DC. Methods: To address this gap, we performed a single-institution retrospective analysis using the Mayo Clinic PSMA PET database. All patients receiving a PSMA PET/CT scan in the interval of January 1, 2021, to December 31, 2022, were eligible for inclusion. Cases were filtered and categorized by histology at the time of diagnosis to select for pure DAC and mixed ductal variants. Trained research personnel annotated disease- and treatment-related variables. A board-certified radiologist performed tumor burden segmentation with calculations of SUV max, total lesion SUV mean and volume, and total lesion uptake, and ascribed a miPSMA expression score. Results: We queried 1792 patients from our PSMA PET/CT registry and identified 32 (1.8%) patients with a pathologically confirmed DC, including 8 (25%) patients with pure ductal and 25 (75%) patients with mixed histology. The indication for PSMA PET/CT was biochemical progression or restaging for 29 (91%) patients and initial staging for 3 (9%) patients. The median (IQR) time from prostate cancer diagnosis to PSMA PET scan was 41.6 (11.5-64.7) months, during this time 50% (n= 16) of patients developed CRPC. At the time of the PSMA PET/CT scan, the median age was 70 years, the median (IQR) PSA was 0.5 ng/mL (0.2-2.6). The distribution of metastatic spread and quantitative imaging parameters from PSMA PET are shown in the Table. Conclusions: Despite low PSA at the time of imaging, PSMA PET/CT frequently detected high volume osseous and/or visceral metastases in patients with DC. However, it is noteworthy that more than 50% of patients with DC had a low miPSMA score (0-1). Additional studies are needed to better understand the performance of novel imaging modalities when evaluating variant prostate cancers. [Table: see text]

In-hospital imaging utilization after elective endovascular brain aneurysm treatment: a surrogate metric for the value of hospitalization.

Despite the adoption of same-day outpatient surgical procedures in some specialties, it remains common practice to admit patients for monitoring after elective endovascular treatment of brain aneurysms to monitor for complications. The necessity of such monitoring has not been fully characterized. Here, the authors reviewed the utilization of imaging during posttreatment hospitalization, a surrogate measure for workup of suspected complications requiring hospital resources, to infer the value of inpatient monitoring after endovascular aneurysm treatment. Clinical and angiographic data from eligible patients were retrospectively assessed for demographic characteristics, imaging indications, timing of imaging, and imaging findings. Patients were included if they underwent elective endovascular brain aneurysm treatment, and patients were excluded if significant intraprocedural complications occurred. The recorded imaging modalities included CT, MRI, catheter-based imaging, and ultrasound; plain radiographs were excluded. Multivariable logistic regression analysis was performed to identify predictors of the need for posttreatment imaging. In total, 1229 elective endovascular procedures for brain aneurysm treatment were included. Patients underwent imaging before discharge in 13.4% (165/1229) of cases, with significant findings in 5.0% (61/1229) of cases. The median (interquartile range) time to first posttreatment imaging was 13.2 (4.2-22.8) hours. The need for imaging during posttreatment hospitalization was positively associated with larger aneurysm size (p < 0.05) and negatively associated with underlying cardiovascular disease (p < 0.05). More than 1 in 8 patients who underwent elective endovascular brain aneurysm treatment required imaging during posttreatment hospitalization, most within the first 24 hours, and 1 in 20 had significant findings. These results suggest the importance of short-term hospitalization after elective endovascular aneurysm treatment.

Sparse-view image reconstruction with total-variation minimization applied to sparsely sampled projection data from SiPM-based photon-counting CT

We constructed a sparse-view computed tomography (CT) system that combines a compressed sensing (CS)-based image-reconstruction algorithm and SiPM-based photon-counting (PC) CT. CS-based image-reconstruction algorithms have been extensively studied for X-ray CT image reconstruction using fewer projections because they are expected to reduce CT imaging time and radiation exposure while maintaining CT image quality. In most previous studies, CS-based image-reconstruction algorithms have been applied to data obtained through numerical simulations or conventional dual-energy CT. However, studies on PC-CT have been scarce. Therefore, we applied a CS-based image-reconstruction algorithm to the projection data obtained using our previously established SiPM-based PC-CT system and evaluated its image quality. We prepared static phantoms equivalent to iodine-containing contrast agents and a mouse model injected with iodine-containing contrast agents as subjects. Thereafter, CT scanning was performed. The obtained projection data were downsampled to simulate a sparse-view situation, and a CS-based image-reconstruction algorithm with total-variation minimization was applied. Consequently, sparse-view CT images were successfully reconstructed, and the image quality was maintained even after downsampling the projection data (downsampling ratios of 1/10 and 1/2 for the rod phantom and mouse model, respectively). Thus, the imaging time and exposure dose could be remarkably reduced (by a factor of 10 or 2), indicating that the CS-based image-reconstruction algorithm is effective for PC-CT.

Abstract TP52: Reducing Door-to-Imaging Times in Acute Stroke Patients Presenting to the Emergency Department by Private Vehicle: Triage Hallway versus Room Evaluation

Background: Delays in IV thrombolytic and thrombectomy treatments are associated with worse outcomes after ischemic stroke. The objective of our study was to compare door-to-CT imaging times among Code Stroke patients who presented by private vehicle and were evaluated by a physician in the emergency department (ED) either in the triage hallway or the emergency department room. Methods: We prospectively collected real-time data on Code Stroke patients presenting by private vehicle to a primary stroke center from May 1, 2022 through September 18, 2022. A Code Stroke was activated for all patients presenting to the emergency room with positive BE-FAST symptoms occurring within 24 hours from last known normal time. Patients were evaluated by a physician either in the triage hallway or an ED room prior to CT imaging. We compared baseline demographic data, NIHSS scores and door-to-CT times in patients evaluated by the physician in the ED triage hallway versus the ED room. Results: Of 55 patients who presented to the ED by private vehicle during the study period, the mean age was 54 ± 15 years, 53% were female and 45% non-white. The median NIHSS score was 1 [IQR 0-4]. There were 27 (49%) patients who underwent physician evaluation in the triage hallway and the remaining went into a patient room before going to CT. The median NIHSS scores for evaluations in the room were higher than in the triage hallway (2 vs 0, p=0.037). Overall, median time from door-to-CT was 11 minutes for patients who went directly from the triage hallway to CT and 21 minutes for patients who were roomed prior to CT (p=0.005). Conclusions: This study found that Code Stroke patients presenting by private vehicle and evaluated by an emergency physician in the triage hallway saved 10 minutes in door-to-CT time compared with physician evaluation in a room.

Abstract WP118: Ischemic Core Volumes and Collateral Status Have Diurnal Fluctuations - A Retrospective Cohort Study of 18137 Patients Using Automated Perfusion Imaging

Introduction: Circadian rhythms have recently been shown to influence stroke incidence and progression of infarct. We aimed to describe the diurnal variations in the incidence and perfusion profiles of patients with ischemic stroke using a large, multi-center, automated imaging database. Methods: The RAPID Insights database was queried from 02/01/2016 to 01/31/2022 for patients with perfusion imaging and automated detection of an ischemic stroke due to a presumed large vessel occlusion. Exclusion criteria included: patient age ≤25, mismatch volume of &lt;0 cc, and failure to register a positive value on either cerebral blood flow (CBF) reduction of 38% less than normal or total mismatch volume. Imaging time was subdivided into three epochs: Night: 23:00h-06:59h and Day: 07:00h-14:59h, and Evening: 15:00h-22:59h. Perfusion parameters were defined as the following: core volume was defined as CBF of &lt;30% of normal, penumbra was defined as a Tmax delay of &gt;6 seconds minus core volume, and collateral circulation was estimated with the Hypoperfusion Intensity Ratio (HIR = [Tmax&gt;10s]/[Tmax&gt;6s]), where a higher HIR suggests poorer collateral status. All perfusion parameters were analyzed on a 24-hour continuous cycle. Statistical significance was tested using a sinusoidal regression analysis. Results: A total of 18,137 cases were analyzed. The peak incidence of ischemic stroke occurred around noon. A sinusoidal pattern was present, with larger ischemic core volumes and higher HIR during the night compared to the day: peak ischemic core volume of 23.40 cc occurred with imaging performed at 3:56 AM (p&lt;0.001) and peak HIR of 0.35 at 3:40 AM (p&lt;0.001). Conclusion: We found that ischemic core volumes were larger and collateral status worse at nighttime compared to daytime in this large national database. These findings support the notion that poor collateral recruitment with subsequent larger ischemic stroke volumes may occur at night. Fig 1. Logarithmic values of ischemic core volumes and hypoperfusion intensity ratios (HIR) are plotted against a 24-hour cycle, demonstrating a sinusoidal pattern for both.

Abstract WMP30: Real World Experience With Tenecteplase on a Mobile Stroke Unit

Background: Tenecteplase (TNK) administered on a mobile stroke unit (MSU) has demonstrated superior rates of early reperfusion compared to alteplase. Current guidelines include TNK as a second-tier option for large vessel occlusions as TNK has many benefits, including rapid IV administration and ease of dosing. The objective of this study was to describe real world utilization of TNK on a MSU. Methods: This was a retrospective observational study of patients receiving TNK as compared to alteplase between February 2021 and April 2023 at a large academic comprehensive stroke center. Baseline demographics, GCS, NIHSS, as well as time of initial imaging were collected. Primary endpoint was time from MSU door to thrombolytic administration. Secondary endpoints included: MSU door to imaging interpretation, dispatch to thrombolytic administration, and provider decision time to thrombolytic administration. Safety endpoints included symptomatic ICH within 24 hours. Results: During the studied time period 40 patients received alteplase and 32 patients received TNK on the MSU. The median age was 65.7 years and median NIHSS score was 9. There was no difference in time from MSU door to thrombolytic administration (15 vs 17.5, p=0.30). There was also no difference in time from MSU door to imaging interpretation, dispatch to thrombolytic administration, or provider decision time to thrombolytic administration. No hemorrhagic conversion occurred. Conclusion: This is the largest series to date describing real-world utilization of TNK administration in a MSU. There were no significant differences in time to therapy in any of the time points evaluated. This data is promising for the treatment of ischemic stroke in which time to administration of thrombolytic therapy is paramount and TNK is administered as a rapid IV injection as compared to alteplase infusion.

Time between imaging and surgery is not a risk factor for upstaging of clinical stage IA non-small-cell lung cancer.

The timing of preoperative imaging in patients with lung cancer is a debated topic, as there are limited data on cancer progression during the interval between clinical staging by imaging and pathological staging after resection. We quantified disease progression during this interval in patients with early stage non-small-cell lung cancer (NSCLC) to better understand if its length impacts upstaging. We retrospectively reviewed our institutional database to identify patients who underwent surgery for clinically staged T1N0M0 NSCLC from January 2015 through September 2022. Tumour upstaging between chest computed tomography (CT) and surgery were analysed as a function of time (<30, 30-59, ≥60 days) for different nodule subtypes. We analysed data across 3 timeframes using Pearson's chi-squared and analysis of variance tests. During the study period, 622 patients underwent surgery for clinically staged T1N0M0 NSCLC. CT-to-surgery interval was <30 days in 228 (36.7%), 30-59 days in 242 (38.9%) and ≥60 days in 152 (24.4%) with no differences in patient or nodule characteristics observed between these groups. T-stage increased in 346 patients (55.6%) between CT imaging and surgery. Among these patients, 126 (36.4%) had ground-glass nodules, 147 (42.5%) had part-solid nodules and 73 (21.1%) had solid nodules. CT-to-surgery interval length was not associated with upstaging of any nodule subtype (full-cohort, P = 0.903; ground-glass, P = 0.880; part-solid, P = 0.858; solid, P = 0.959). This single-centre experience suggests no significant association between tumour upstaging and time from imaging to lung resection in patients with clinical stage IA NSCLC. Further studies are needed to better understand the risk factors for upstaging.

Comparison of Different Osteobiologics in Terms of Imaging Modalities and Time Frames for Fusion Assessment in Anterior Cervical Discectomy and Fusion: A Systematic Review.

Systematic review. The study's primary objective was to determine how osteobiologic choice affects fusion rates in patients undergoing anterior cervical discectomy and fusion (ACDF). The study's secondary objectives were to 1) determine the optimal timing of fusion assessment following ACDF and 2) determine if osteobiologic type affects the timing and optimal modality of fusion assessment. A systematic search of PubMed/MEDLINE was conducted for literature published from 2000 through October 2020 comparing anterior fusion in the cervical spine with various osteobiologics. Both comparative studies and case series of ≥10 patients were included. A total of 74 studies met the inclusion criteria. Seventeen studies evaluated the efficacy of autograft on fusion outcomes, and 23 studies assessed the efficacy of allograft on fusion outcomes. 3 studies evaluated the efficacy of demineralized bone matrix, and seven assessed the efficacy of rhBMP-2 on fusion outcomes. Other limited studies evaluated the efficacy of ceramics and bioactive glasses on fusion outcomes, and 4 assessed the efficacy of stem cell products. Most studies utilized dynamic radiographs for the assessment of fusion. Overall, there was a general lack of supportive data to determine the optimal timing of fusion assessment meaningfully or if osteobiologic type influenced fusion timing. Achieving fusion following ACDF appears to remain an intricate interplay between host biology and various surgical factors, including the selection of osteobiologics. While alternative osteobiologics to autograft exist and may produce acceptable fusion rates, limitations in study methodology prevent any definitive conclusions from existing literature.

Signal Quantification of Intravenous Contrast Agents Enhancement from Biphase Liver CT Scan Procedures

In multi-detector computed tomography (MDCT) abdominal and pelvic CT treatments with intravenous (IV) contrast media (CM), automated bolus monitoring with a fixed contrast enhancement delay was examined. Statistics assess all contrast enhancement variables, including patient data like body weight, cardiac output, and contrast injection settings. This study comprised 100 retrospective and 43 prospective patients. In the first group, the Hounsfield unit (HU) was measured before, 30 seconds, and 70 seconds after CM. The second group measured age, weight, heart rate, systolic and diastolic blood pressure, and creatinine. The radiographer computed CM time based on HU values around 120. The differences in HU levels across groups were used to create an equation for imaging time prediction utilizing auto-mated bolus monitoring. The Bolus Time Equation’s predictors included patient weight, heart rate, creatinine level, and systolic blood pressure, with 34.9% dependency and 59.1% influence on each variable. The equation is trustworthy since the ANOVA test indicated p = 0.002. The computation and study gave the same Bolus Time value with a p-value of (0.992 > 0.05). The first and second groups exhibited very different HU rates (p-value 0.00). The research found that fixed-time improved more than bolus monitoring, which performed better.

Electronics design for a muon imaging system using triangular plastic scintillators with WLS fiber readouts

Muon imaging technology has developed rapidly over the past decades with extensive applications. In many cases, plastic scintillator detectors are preferred because of their high cost performance, ease of processing and robustness in harsh environments. To reduce imaging time and improve imaging quality, detectors tend to have large areas and high position resolutions. The challenge to the electronics for such detectors is to maintain the scale of electronics acceptable while improving the high position resolution of the detector. In this paper, the basic detector unit is a triangular strip of plastic scintillator, each embedded with two wavelength-shifting (WLS) fibers read out by the silicon photomultipliers (SiPMs). Since the hit position of muon on the detector is determined by the splitting ratio of the scintillation light on two adjacent scintillator strips, it is necessary the readout electronics has high linearity and low noise. The possibility of the electronics channel multiplexing on the same detector plane is fully explored so that four WLS fibers can be read out by one SiPM realizing 2:1 readout channel compression. Furthermore, since multiple electronics modules are connected by a daisy chain structure, the electronics system is very scalable with its data acquisition system (DAQ) independent of detector size. In addition to detailing the position encoding readout scheme, the design of electronics module and the DAQ system, the electronics system has been implemented and applied to a prototype detector for performance evaluation. Using scintillator strips with 11 mm pitch size, the position resolution of the detector reaches 1.49 mm, which demonstrates that the designed electronics is suitable for the new detector structure, and the combination of the two has a good application prospect in muon imaging.

Abstract TP175: Older Age is Associated With Smaller Ischemic Core Volume and Slower Infarct Progression Despite High Clinical Severity in Anterior Circulation Large Vessel Occlusion Stroke

Background: Older patients with acute stroke due to anterior circulation large vessel occlusion (ACLVO) experience worse clinical outcomes. Fast progressors typically present early with high stroke severity and larger ischemic core volumes. However, the relationship between aging and early infarct growth rate is unknown. We examined the association between older age, baseline ischemic core volumes and fast or slow infarct growth during ACLVO. Methods: Retrospective study of patients with acute ICA or MCA occlusion across two academic centers in 2014-2019. Patients were included if they had baseline CTP or MRI within 24 hours after estimated stroke onset. Infarct growth rate (IGR) was calculated as ischemic core volume (ml) / stroke onset to imaging time (h). Fast or Slow progressor status was defined by IGR ≥ or &lt; 10 ml/h. Univariate comparisons were made across age tertiles. Multivariable linear and logistic regression analysis examined the association of age tertile with ischemic core volume and slow progressor status adjusting for sex, vascular co-morbidities and NIHSS. Results: We included 312 patients (57% female; age tertiles [T1-T3]: 33—66, 67—81, and 82—102). Older age was associated with decreasing ischemic core volume (median [range] ml: T1, 29 [0-253]; T2, 12 [0-406]; T3, 6 [0-244]; p&lt;0.001) and lower IGR (median [range] ml/h: T1, 5.8 [0-153]; T2, 2.6 [0-122.5]; T3, 0.6 [0-248]; p&lt;0.001). The frequency of slow progressors increased with age (N (%): T1, 65/107 (61); T2, 76/105 (72); T3, 78/100 (78); p=0.02). However, baseline NIHSS was numerically higher with older age (median [range]: T1, 16 [1-30]; T2, 17 [2-38]; T3, 18 [1-33]; p=0.22). In multivariable models, age tertile (T3 vs T1) and NIHSS were associated with: 1. ischemic core volume (age coefficient [95% CI], -18.9 [-36.1, -1.7], p=0.03; NIHSS coefficient [95% CI], 3.2[2.3, 4.1], p&lt;0.001); and 2. slow progressor status (age OR 2.63 [1.27, 5.43], p=0.009); NIHSS OR 0.91 [0.87, 0.95], p&lt;0.001). Conclusions: Older age was paradoxically associated with lower baseline core volumes and slow progressor status, despite high stroke severity during acute ACLVO, suggesting older patients may be more vulnerable to even slow infarct growth. Future studies are needed to confirm and extend the findings.

Abstract WP125: The Presence of a Ghost Infarct Core is Associated With Fast Core Growth in Acute Ischemic Stroke

Introduction: The overestimation of ischemic core volume by computed tomography perfusion (CTP) is a critical concern in the selection of candidates for reperfusion therapy. This phenomenon is termed a ghost infarct core (GIC). Core growth rate has emerged as an indicator of ischemic severity. The aim of the present study was to elucidate the association between the presence of a GIC and the core growth rate. Methods: Consecutive patients with acute ischemic stroke due to large vessel occlusion who underwent mechanical thrombectomy in our institute from March 2017 to July 2022 were enrolled. The initial ischemic core was measured by pretreatment CTP, and the final infarct volume (FIV) was measured by diffusion-weighted imaging. A GIC was defined by initial ischemic core volume minus FIV &gt;10 mL. The core growth rate was calculated by dividing the initial ischemic core volume by time from stroke onset to CTP acquisition. Univariable analysis and a multivariable logistic regression model were used to evaluate the association between GIC-positive and the core growth rate; complete recanalization, onset to imaging time, and imaging to recanalization time were included as covariates. Results: Ninety-one patients were included in the study. Of these, 21 patients (23.1%) were GIC-positive. The GIC-positive group had higher core growth rate (14.2 [2.6-46.7] vs 4.8 [1.6-17.1] mL/h, p=0.021) and complete recanalization (n=15 (71.4%) vs 29 (41.4%), p=0.016) compared to the GIC-negative group. On receiver operating characteristic curve analysis, the optimal cutoff point of the core growth rate to predict GIC-positive was 22 mL/h (sensitivity, 0.48; specificity, 0.85; area under the curve, 0.67). Multivariable logistic regression analysis showed that core growth rate ≥22 mL/h (OR 6.44, 95% CI [1.59-26.10], p=0.006) and complete recanalization (OR 3.72, 95% CI [1.14-12.08], p=0.022) were independent predictors of GIC-positive. Conclusions: A GIC was associated with fast core growth in acute ischemic stroke. Overestimation of the initial ischemic core may be determined by core growth speed, not a clock time.

Emerging Concept of Intracranial Arterial Diseases: The Role of High Resolution Vessel Wall MRI.

Intracranial arterial disease (ICAD) is a heterogeneous condition characterized by distinct pathologies, including atherosclerosis. Advances in magnetic resonance technology have enabled the visualization of intracranial arteries using high-resolution vessel wall imaging (HR-VWI). This review summarizes the anatomical, embryological, and histological differences between the intracranial and extracranial arteries. Next, we review the heterogeneous pathophysiology of ICAD, including atherosclerosis, moyamoya or RNF213 spectrum disease, intracranial dissection, and vasculitis. We also discuss how advances in HR-VWI can be used to differentiate ICAD etiologies. We emphasize that one should consider clinical presentation and timing of imaging in the absence of pathology-radiology correlation data. Future research should focus on understanding the temporal profile of HR-VWI findings and developing quantitative interpretative approaches to improve the decision-making and management of ICAD.

Time-Saving 3D MR Imaging Protocols with Millimeter and Submillimeter Isotropic Spatial Resolution for Face and Neck Imaging as Implemented at a Single-Site Major Referral Center.

MR imaging has become the routine technique for staging nasopharyngeal carcinoma, evaluating perineural tumor spread, and detecting cartilage invasion in laryngeal carcinoma. However, these protocols traditionally require in the range of 25 to 35 minutes of acquisition time. 3D sequences offer the potential advantage of time savings through the acquisition of 1-mm or submillimeter resolution isotropic data followed by multiplanar reformats that require no further imaging time. We have iteratively optimized vendor product 3D T1-weighted MR imaging sequences for morphologic face and neck imaging, reducing the average acquisition time of our 3T protocols by 9 minutes 57 seconds (40.9%) and of our 1.5T protocols by 9 minutes 5 seconds (37.0%), while simultaneously maintaining or improving spatial resolution. This clinical report describes our experience optimizing and implementing commercially available 3D T1-weighted MR imaging pulse sequence protocols for clinical face and neck MR imaging examinations using illustrative cases. We provide protocol details to allow others to replicate our implementations, and we report challenges we faced along with our solutions.

Clinical parameters for the early detection of complications in patients with blunt hepatic and/or splenic injury undergoing non-operative management.

Complications arising during non-operative management (NOM) of blunt hepatic and/or splenic trauma, particularly in cases of severe injury, are associated with significant morbidity and mortality. Abdominal computed tomography (CT) is the gold standard for the initial detection of complications during NOM. Although many institutions advocate routine in-hospital follow-up scans to improve success rates, others recommend a more selective approach. The use of follow-up CT remains a subject of ongoing debate, with no validated guidelines available regarding the timing, effectiveness, or intervals of follow-up imaging. We aimed to identify the clinical parameters for the early detection of complications in patients with blunt hepatic and/or splenic injury undergoing NOM. This retrospective cohort study included patients with blunt hepatic and/or splenic trauma treated at Songklanagarind Hospital, a level 1 trauma center, from 2013 to 2022. We assessed all patients indicated for non-operative management and examined their clinical parameters and complications. Of 542 patients with blunt hepatic and/or splenic injuries, 315 (58%) were managed non-operatively. High-grade hepatic injuries were significantly associated with complications, as determined through a multivariate logistic regression analysis after adjusting for factors such as contrast blush findings, age, sex, and injury severity score (ISS) (adjusted OR = 7.69, 95% CI 1.59-37.13; p = 0.011). Among the patients with complications (n = 27), 17 (63%) successfully underwent non-operative management. Notably, eight patients presented with clinical symptoms prior to the diagnosis of complications, while only two patients had no clinical symptoms before the diagnosis. Tachycardia, abdominal pain, decreased hematocrit levels, and fever were significant indicators of complications (p < 0.05). Routine CT to detect complications may not be necessary in patients with asymptomatic low-grade blunt hepatic injuries. By contrast, in those with isolated blunt hepatic injuries that are managed non-operatively, high-grade injuries, the presence of a contrast blush on initial imaging, and the patient's age may warrant consideration for routine follow-up CT scans. Clinical symptoms and laboratory observations during NOM, such as tachycardia, abdominal pain, decreased hematocrit levels, and fever, are significantly associated with complications. These symptoms necessitate further management, regardless of the initial injury severity, in patients with blunt hepatic and/or splenic injuries undergoing NOM.

An efficient cheating-detectable secret image sharing scheme with smaller share sizes

As a new approach to image protection, polynomial-based secret image sharing (PSIS) has attracted a lot of attention from many researchers in recent decades. When SIS technology is applied in practice, it is inevitably subject to various types of attacks, with cheating being the most likely to occur. To deal with the cheating problem in the process of secret image reconstruction, several effective (k,n)-PSIS schemes have been proposed. However, most previous schemes need to sacrifice the size of the share to achieve cheating detection capability. To address this issue, an efficient cheating-detectable (k,n)-PSIS scheme with smaller share sizes is designed based on the singularity of square matrix in this paper. In comparison with previous schemes, the proposed one can not only detect the complicity of up to k−1 cheaters, but also reduce the size of shares to 1k times of the secret image. Moreover, the secret image can be recovered without loss, and it does not need to be scrambled before sharing, which could reduce the complexity of the scheme. Theoretical proofs and experiments show that the contrast and security conditions of the proposed scheme are satisfied, and the cheating detection capability is available as well.