Late Imaging Research Articles

Optimizing fibrosis detection: a comparison of electroanatomical mapping and late enhancement gadolinium magnetic resonance imaging.

Fibrotic atrial cardiomyopathy plays an important role in determining the outcome of ablation in patients with atrial fibrillation (AF). Two main methods are being used for the evaluation of fibrosis: voltage-based high-density (HD) electroanatomical mapping (EAM) and late gadolinium enhancement MRI (LGE-MRI). The comparability between both methods in detecting fibrosis has not been systematically investigated. LGE-MRIs of the left atrium (LA) were performed in 21 patients. LA-fibrosis was evaluated using a custom-designed software generating a 3D-model of the LA. HD-electroanatomical maps were recorded in each patient. After processing the maps and the MRI models by excluding the mitral valve, pulmonary veins, and the left atrial appendage, the LGE areas were measured and compared to the low voltage areas (LVA) in the HD maps using three different cutoff values of 0.5 mV, 0.7 mV, and 1.0 mV. The analysis revealed significant differences between EAM and LGE-MRI in assessing LA-fibrosis at 0.5-mV (for anterior and posterior walls) and 1.0-mV cutoffs (for anterior and posterior wall and septum). However, no significant differences were found between EAM and LGE-MRI when using a 0.7-mV cutoff for all the investigated areas. A voltage cutoff of 0.7 mV provided the best correlation between EAM and LGE MRI for detecting left atrial fibrosis. It supports the idea that a 0.5-mV cutoff may underestimate fibrosis, as areas with local signal voltages between 0.6 and 0.8 mV could also show LGE on MRI. Further research is needed to determine the ideal voltage cutoff for detecting left atrial fibrosis.

Spleen-preserving pancreatectomy with removal of splenic vessels: impact on splenic parenchyma ?

BackgroundWhile outcomes after spleen-preserving distal pancreatectomy (SP-DP) have been widely reported, impacts on splenic parenchyma have not been well studied. This study aimed to compare postoperative outcomes, particularly spleen-related outcomes, by assessing splenic imaging after SP-DP with or without splenic vessels removal.MethodsData for all patients who underwent SP-DP with splenic vessels removal (Warshaw technique, WDP) or preservation (Kimura technique, KDP) between 2010 and 2022 in two tertiary centres were retrospectively analysed. Splenic ischemia and volume at early/late imaging and postoperative outcomes were reviewed.ResultsEighty-seven patients were included, 51 in the WDP and 36 in the KDP groups. Median Charlson’s Comorbidity Index was significantly higher in the WDP group compared with the KDP group. Postoperative morbidity was similar between groups. There was more splenic ischemia at early imaging in the WDP group compared to the KDP group (55% vs. 14%, p = 0.018), especially severe ischemia (23% vs. 0%). Partial splenic atrophy was observed in 29% and 0% in the WDP and KDP groups, respectively (p = 0.002); no complete splenic atrophy was observed. Platelet levels at POD 1, 2 and 6 were significantly higher in the WDP group compared to KDP group. At univariate analysis, age, Charlson Comorbidity Index, platelet levels at POD 6, and early splenic infarction were prognostic factors for development of splenic atrophy. No episodes of overwhelming post-splenectomy infection or secondary splenectomy were recorded after a median follow-up of 9 and 11 months in the WDP and KDP groups, respectively.ConclusionsSplenic ischemia appeared in one-half of patients undergoing SP-DP with splenic vessels removal at early imaging, and partial splenic atrophy in almost 30% at late imaging, without clinical impact or complete splenic atrophy. Age, Charlson Comorbidity Index, platelet levels at POD 6, and early splenic infarction could help to predict the occurrence of splenic atrophy.

Septal scar as a barrier to left bundle branch area pacing.

The use of left bundle branch area pacing (LBBAP) for bradycardia pacing and cardiac resynchronization is increasing, but implants are not always successful. We prospectively studied consecutive patients to determine whether septal scar contributes to implant failure. Patients scheduled for bradycardia pacing or cardiac resynchronization therapy were prospectively enrolled. Recruited patients underwent preprocedural scar assessment by cardiac MRI with late gadolinium enhancement imaging. LBBAP was attempted using a lumenless lead (Medtronic 3830) via a transeptal approach. Thirty-five patients were recruited: 29 male, mean age 68years, 10 ischemic, and 16 non-ischemic cardiomyopathy. Pacing indication was bradycardia in 26% and cardiac resynchronization in 74%. The lead was successfully deployed to the left ventricular septum in 30/35 (86%) and unsuccessful in the remaining 5/35 (14%). Septal late gadolinium enhancement was significantly less extensive in patients where left septal lead deployment was successful, compared those where it was unsuccessful (median 8%, IQR 2%-18% vs. median 54%, IQR 53%-57%, p<.001). The presence of septal scar appears to make it more challenging to deploy a lead to the left ventricular septum via the transeptal route. Additional implant tools or alternative approaches may be required in patients with extensive septal scar.

In vivo imaging of the neuronal response to spinal cord injury: a narrative review.

Deciphering the neuronal response to injury in the spinal cord is essential for exploring treatment strategies for spinal cord injury (SCI). However, this subject has been neglected in part because appropriate tools are lacking. Emerging in vivo imaging and labeling methods offer great potential for observing dynamic neural processes in the central nervous system in conditions of health and disease. This review first discusses in vivo imaging of the mouse spinal cord with a focus on the latest imaging techniques, and then analyzes the dynamic biological response of spinal cord sensory and motor neurons to SCI. We then summarize and compare the techniques behind these studies and clarify the advantages of in vivo imaging compared with traditional neuroscience examinations. Finally, we identify the challenges and possible solutions for spinal cord neuron imaging.

Contrast-enhanced ultrasound with microbubbles containing sulfur hexafluoride and perfluorobutane with Kupffer phase for the detection of colorectal liver metastases.

To compare contrast-enhanced ultrasound (CEUS) with microbubbles containing sulfur hexafluoride (SHF) and perfluorobutane (PFB) for the detection of colorectal liver metastasis (CRLM). In this prospective study, conducted from September to November 2021, patients with colorectal cancer were consecutively recruited and underwent same-day ultrasound, SHF-CEUS, and PFB-CEUS. The reference standard was contrast-enhanced MRI and follow-up imaging. The size, depth, echogenicity, and calcification of each focal liver lesion were recorded. The number and conspicuity of CRLMs, based on washout appearance during the late phase (LP) (> 120 s)/Kupffer phase (KP), were evaluated offsite by two blinded readers. Overall, 230 lesions (CRLMs, n= 219; benign lesions, n= 11) in 78 patients were evaluated. Lesion conspicuity (p= 0.344) and accuracy in the detection of CRLM were comparable for SHF- and PFB-CEUS (0.877 for SHF vs. 0.770 for PFB, p= 0.087). More CRLMs ≥ 10 mm were identified by LP contrast washout in SHF-CEUS than in KP PFB-CEUS (p< 0.001). More CRLMs < 10 mm were identified by KP washout in PFB-CEUS than in LP SHF-CEUS (p< 0.001). Conspicuity was better on PFB-CEUS than on SHF-CEUS (p= 0.027). In hyperechoic lesions, lesions located deeper than 80 mm, and calcified lesions, CRLM conspicuity on PFB-CEUS was inferior to that on SHF-CEUS (p< 0.05). The overall accuracy of detection and conspicuity of washout in CRLMs were comparable between SHF and PFB-CEUS. PFB-CEUS has the advantage of identifying washout in small CRLMs. However, larger, hyperechogenic, deep-seated, or calcified lesions were better identified using SHF-CEUS. Accuracy of detection and conspicuity of washout in CRLMs were comparable between SHF- and PFB-CEUS. PFB-CEUS has the advantage in detecting small CRLMs, whereas SHF-CEUS is better for detecting larger, hyperechogenic, deep-seated, or calcified lesions. Contrast-enhanced ultrasound with sulfur hexafluoride in the late phase and perfluorobutane microbubbles in the Kupffer phase were comparable in terms of accuracy in the detection and conspicuity of colorectal liver metastases. Small colorectal liver metastases (< 10 mm) were more often identified in the Kupffer phase contrast-enhanced ultrasound imaging when using perfluorobutane microbubbles. Larger, hyperechogenic, deep-seated, or calcified lesions were better identified in the late phase contrast-enhanced ultrasound imaging (> 120 s) when using sulfur hexafluoride microbubbles.

Evaluation of Interstitium by Lymphatic Uptake Method in Chronic Bilateral Lower Extremity Edema.

Symmetrical bilateral lower extremity edema (BLEE) needs to be treated effectively. Finding the cause of this condition increases the success of treatment. Fluid increase in the interstitial space (FIIS) is always present as a cause or a result. Subcutaneously administered nanocolloid is transported by uptake by lymphatic pre-collectors, and this uptake takes place in the interstitium. We aimed to evaluate the interstitium with labeled nanocolloid and contribute to the differential diagnosis in cases with BLEE. Our retrospective study included 74 female patients who underwent lymphoscintigraphy for bilateral lower extremity edema. Technetium 99m (Tc-99m) albumin colloid (nanocolloid), a marked colloidal suspension, was applied subcutaneously to two different areas on the dorsum of both feet with a 26 gauge needle The dose volume administered intradermally is approximately 0.2-0.3 ml, and each injector has 22-25MBq of activity. Siemens E-Cam dual-headed SPECT gamma camera was used for imaging. Dynamic and scanning images were taken with a high-resolution parallel hole collimator. Ankle images were re-evaluated by two nuclear medicine specialists, independent of physical examination and scintigraphy findings. 74 female patients with bilateral lower extremity edema were divided into two groups based on physical examination and lymphoscintigraphy findings. There were 40 and 34 patients in Groups I and II, respectively. In the physical examination, patients in Group I were evaluated as lymphedema, and patients in Group II were evaluated as lipedema. The main lymphatic channel (MLC) was not observed in any of the patients in Group I in the early images, and the MLC was observed at a low level in the late imaging in 12 patients. The sensitivity of the presence of distal collateral flows (DCF) in the presence of significant MLC in early imaging in demonstrating increased fluid in the interstitial space (FIIS) was calculated as 80%, specificity as 80%, PPV 80%, and NPV 84%. While MLC is present in early images, concomitant DCF occurs in cases of lipoedema. The transport of increased lymph fluid production in this group of patients can be covered by the existing MLC. Although MLC is evident, the presence of significant DCF supports the presence of lipedema. It can be used as an important parameter in the diagnosis in early cases where physical examination findings are not evident.

Distribution of leakage index using ultra-widefield fluorescein angiography in patients with non-ischemic branch retinal vein occlusion and its association with macular edema

BackgroundTo investigate the distribution of leakage index in patients with non-ischemic branch retinal vein occlusion (BRVO) and its correlation with the severity of macular edema. MethodsRetrospective observational study. Forty-five eyes of 45 patients with BRVO were included. Late ultra-widefield fluorescein angiography images of the affected eyes were processed and analyzed for their leakage index using Fiji software. The visible panretinal area was further divided into the peri‑macular area (PMA), near-peripheral area (NPA), midperipheral area (MPA), and far-peripheral area (FPA). The relationship between the leakage index and central retinal thickness (CMT) was analyzed for the panretina and each subregion. ResultsThe median (interquartile range) leakage indexes of the panretina, PMA, NPA, MPA, and FPA were 5.532% (7.667%), 23.127% (26.073%), 8.303% (16.807%), 1.588% (6.204%), and 0.408% (2.215%), respectively, with a mean CMT of 552.800 ± 183.335 μm. The CMT was positively correlated with the leakage index in the panretina, PMA, NPA, MPA and FPA (r = 0.468, 0.426, 0.463, 0.447, 0.320, respectively; all p < 0.05). ConclusionsThe leakage index in non-ischemic BRVO patients is associated with macular edema severity. The leakage index has the potential to be a useful indicator for monitoring and guiding treatment of macular edema in BRVO patients.

Differences in atrial substrate localization using late gadolinium enhancement-magnetic resonance imaging, electrogram voltage, and conduction velocity: a cohort study using a consistent anatomical reference frame in patients with persistent atrial fibrillation.

Electro-anatomical voltage, conduction velocity (CV) mapping, and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) have been correlated with atrial cardiomyopathy (ACM). However, the comparability between these modalities remains unclear. This study aims to (i) compare pathological substrate extent and location between current modalities, (ii) establish spatial histograms in a cohort, (iii) develop a new estimated optimized image intensity threshold (EOIIT) for LGE-MRI identifying patients with ACM, (iv) predict rhythm outcome after pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF). Thirty-six ablation-naive persistent AF patients underwent LGE-MRI and high-definition electro-anatomical mapping in sinus rhythm. Late gadolinium enhancement areas were classified using the UTAH, image intensity ratio (IIR >1.20), and new EOIIT method for comparison to low-voltage substrate (LVS) and slow conduction areas <0.2 m/s. Receiver operating characteristic analysis was used to determine LGE thresholds optimally matching LVS. Atrial cardiomyopathy was defined as LVS extent ≥5% of the left atrium (LA) surface at <0.5 mV. The degree and distribution of detected pathological substrate (percentage of individual LA surface are) varied significantly (P < 0.001) across the mapping modalities: 10% (interquartile range 0-14%) of the LA displayed LVS <0.5 mV vs. 7% (0-12%) slow conduction areas <0.2 m/s vs. 15% (8-23%) LGE with the UTAH method vs. 13% (2-23%) using IIR >1.20, with most discrepancies on the posterior LA. Optimized image intensity thresholds and each patient's mean blood pool intensity correlated linearly (R2 = 0.89, P < 0.001). Concordance between LGE-MRI-based and LVS-based ACM diagnosis improved with the novel EOIIT applied at the anterior LA [83% sensitivity, 79% specificity, area under the curve (AUC): 0.89] in comparison to the UTAH method (67% sensitivity, 75% specificity, AUC: 0.81) and IIR >1.20 (75% sensitivity, 62% specificity, AUC: 0.67). Discordances in detected pathological substrate exist between LVS, CV, and LGE-MRI in the LA, irrespective of the LGE detection method. The new EOIIT method improves concordance of LGE-MRI-based ACM diagnosis with LVS in ablation-naive AF patients but discrepancy remains particularly on the posterior wall. All methods may enable the prediction of rhythm outcomes after PVI in patients with persistent AF.

Multimodality Imaging of Cardiac Paragangliomas.

Paragangliomas are rare neuroendocrine tumors of extra-adrenal autonomic paraganglia origin. Paragangliomas rarely involve the heart, and they account for less than 1% of primary cardiac tumors. Most cardiac paragangliomas are incidentally detected at echocardiography or CT or during the workup of symptomatic patients with high catecholamine levels. Paragangliomas are typically located around the great vessels, coronary arteries (atrioventricular groove), or the atria, which can be explained by the tumor origin from the paraganglia and the distribution of the cardiac plexus. At MRI, cardiac paragangliomas typically have low to intermediate signal on T1-weighted images and high signal on T2-weighted images. The tumors are strongly vascularized, with high uptake on first-pass perfusion images and a heterogeneous pattern on late gadolinium enhancement images. Functional imaging is indicated for diagnostic confirmation and to screen for additional tumor locations or metastatic disease. Surgical excision is the only curative treatment. Cardiac CT angiography or invasive angiography should be performed preoperatively to precisely delineate tumor vascularization. In particular, its relation with the coronary arteries should be determined, as paragangliomas can be perfused by the coronary arteries, posing additional surgical challenges and the need for coronary revascularization. This imaging essay reviews the characteristics of paragangliomas and the use of multimodality imaging for diagnosis and treatment. Keywords: CT Angiography, Molecular Imaging, MR Imaging, PET/CT, Cardiac, Heart, Neoplasms-Primary © RSNA, 2023.

Sex differences in 123I-mIBG scintigraphy imaging techniques in patients with heart failure

ABSTRACT Background 123I-mIBG-scintigraphy could be a useful stratifying tool for patients with heart failure (HF). The purpose of this retrospective study is to evaluate whether there are differences between men and women with HF in terms of the prediction of cardiac arrhythmic events (AE). Research and methods A total of 306 patients, before implantable-cardioverter-defibrillator (ICD) implantation, were evaluated. They underwent 123I-mIBG-scintigraphy and an evaluation of the results was performed after 85 months of follow-up. Early and late planar and SPECT cardiac images were acquired. Heart-to-mediastinum ratio (HM) for planar images and the sum of the segmental scores (SS) for SPECT were calculated. Results In the general population, age, early SS (ESS), late SS (LSS), and ejection fraction (EF) were statistically significant for the prediction of AE at Cox regression, while early and late HM (eHM,lHM) were not significative for the prediction of AE. Population was divided into females and males and univariate analysis was conducted separately for the two cohorts: no significant variables for prediction of AE were found in females. For males, ESS, LSS, EF, and late HM were statistically significant predictors of AE. The overall survival was similar in males and females, but the risk of AE is lower in males than in females. Conclusions 123I-mIBG represents a more effective tool for the prediction of AE in male patients than in women.

Half-Dose versus Single-Dose Gadobutrol for Extracellular Volume Measurements in Cardiac Magnetic Resonance.

Cardiac magnetic resonance (CMR) imaging with gadolinium-based contrast agents offers unique non-invasive insights into cardiac tissue composition. Myocardial extracellular volume (ECV) has evolved as an objective and robust parameter with broad diagnostic and prognostic implications. For the gadolinium compound gadobutrol, the recommended dose for cardiac imaging, including ECV measurements, is 0.1 mmol/kg (single dose). This dose was optimized for late enhancement imaging, a measure of focal fibrosis. Whether a lower dose is sufficient for ECV measurements is unknown. We aim to evaluate the accuracy of ECV measurements using a half dose of 0.05 mmol/kg gadobutrol compared to the standard single dose of 0.1 mmol/kg. From a contemporary trial (NCT04747366, registered 10 February 2021), a total of 25 examinations with available T1 mapping before and after 0.05 and 0.1 mmol/kg gadobutrol were analyzed. ECV values were calculated automatically from pre- and post-contrast T1 relaxation times. T1 and ECV Measurements were performed in the midventricular septum. ECV values after 0.05 and 0.1 mmol/kg gadobutrol were correlated (R2 = 0.920, p < 0.001). ECV values after 0.05 mmol/kg had a bias of +0.9% (95%-CI [0.4; 1.4], p = 0.002) compared to 0.1 mmol/kg gadobutrol, with limits of agreement from -1.5 to 3.3%. CMR with a half dose of 0.05 mmol/kg gadobutrol overestimated ECV by 0.9% compared with a full dose of 0.1 mmol/kg, necessitating adjustment of normal values when using half-dose ECV imaging.

Long-Term Outcomes and Growth Analysis of Costochondral Grafts for Hemifacial Microsomia: 24-Year Experience of a Single Surgeon.

Costochondral grafts (CCGs) can be used in mandibular reconstruction of Kaban-Pruzansky IIB/III hemifacial microsomia (HFM). Their growth is variable, occasionally necessitating secondary surgery. This study examined one surgeon's 24-year experience to better quantify long-term outcomes and surgical care required in CCG reconstruction of HFM mandibles. Serial 3-dimensional computed tomography scans, from preoperative to most recent, were analyzed in patients with a minimum of 4 years of clinical follow-up after CCG reconstruction. Graft/ramus height, length, volume, bilateral mandibular body length, and chin deviation were measured. Changes in measurements were analyzed preoperatively, immediately postoperatively, at the most recent imaging before secondary surgery, and at the most recent imaging overall. Growth rates per measure were calculated using scans after CCG but before secondary surgery. Thirteen patients were analyzed. Median (SD) clinical follow-up was 10.0 (5.1) years. One patient developed temporomandibular joint ankylosis secondary to stacked-graft malposition, which was repaired without further complications. CCG reconstruction led to immediate improvement in graft/ramus height ( P = 0.03), length ( P = 0.002), and volumetric symmetry ( P = 0.02). No difference was found between graft and native ramus height ( P = 0.4) or length measures ( P = 0.5), whereas graft volume and the affected mandibular body grew significantly more slowly. According to the latest imaging, 63% of patients required secondary surgery, including distraction osteogenesis or orthognathic surgery, due to differential graft or hemimandible growth behavior. Based on the most recent clinical follow-up, this proportion increased to 93%. CCGs provide significant short-term mandibular and facial symmetry improvement in HFM IIB/III. Long-term analysis reveals frequent undergrowth requiring secondary intervention to promote and maintain symmetry. Therapeutic, IV.

Comprehensive Grading System for Experimental Autoimmune Uveitis in Mice.

Experimental autoimmune uveitis (EAU) is the most commonly used animal model to study the progression of chronic uveitis and to test various therapies to treat the disease. However, to accurately evaluate the effectiveness of such treatments, a grading system that combines the latest imaging techniques with definitive quantitative grading thresholds is required. This study aimed to develop a comprehensive grading system that objectively evaluates EAU progression in C57BL/6J mice. EAU was induced following immunisation with interphotoreceptor retinoid-binding protein (IRBP) and pertussis toxin. Weekly fundus and optical coherence tomography (OCT) images were acquired over 12 weeks using a Micron IV imaging system. Each mouse was graded (between 0 to 4) based on changes seen on both the fundus (optic disc, retinal blood vessels and retinal tissue) and OCT (vitreous and retinal layers) images. A total EAU response (with a maximum score of 48) was calculated for each mouse based on the sum of the individual scores each week. Analysis of the clinical scores depicted a gradual increase in inflammatory signs including optic disc and vascular swelling, leukocyte infiltration in the vitreous, lesions in the retina and formation of granulomas and hyper-reflective foci in the retinal layers in EAU mice, with most signs reaching a plateau towards the end of the study period. Development of these signs into sight-threatening complications such as optic disc atrophy, structural damage to the retina and subretinal oedema were noted in 80-90% of mice suggesting consistent disease induction. Overall, a comprehensive and objective grading system encompassing all pathologies occurring in EAU mice was developed to enhance the preclinical evaluation of novel uveitis treatments.

Effect of Obesity on Lymphatic Fluid Filtration in Inguinal Lymph Nodes

Objective: The objective of this study was to investigate the potential impact of radionuclide imaging on filtration in the inguinal lymph nodes of obese patients. We aimed to compare the lymphatic transport after the inguinal lymph nodes between obese patients and normal-weight individuals, while ensuring intact lower extremity lymphatic flow. Methods: A retrospective study design was employed, involving the re-evaluation of patient images. Among the total of 119 patients, 62 were classified as obese, while the remaining patients had body mass indexes within normal limits. All patients included in the study were female, with a mean age of 39 years (ranging from 28 to 47 years). Lymphatic imaging was performed using Tc-99m-labeled nanocolloid particles with a size of 50-70 nm. The nanocolloid was applied to the 1st and 2nd interdigital web areas on the dorsum of both feet. Late images were captured at 45-50 minutes and 2 hours after application. Results: Out of the 119 patients, 62 (52%) were classified as obese. There was no significant difference in terms of age between the two groups. The pre-inguinal average count values, calculated from the counts before the inguinal node, did not show a significant difference between the two groups. However, the post-inguinal average count values obtained after the inguinal nodes were significantly lower in obese patients compared to normal-weight patients (p&lt;0.0005). Conclusion: Our findings suggest that even in the early stages, when functional imaging allows observation of the main lymphatic duct, there are differences in the progression of lymphatic flow between obese patients and normal-weight individuals. Detecting these differences may enable early diagnosis of lymphedema disease, which is a reversible disorder if identified promptly.

Can We Trust the Phone Vendors? Comprehensive Security Measurements on the Android Firmware Ecosystem

Android is the most popular smartphone platform with over 85% market share. Its success is built on openness, and phone vendors can utilize the Android source code to make customized products with unique software/hardware features. On the other hand, the fragmentation and customization of Android also bring many security risks that have attracted the attention of researchers. Many efforts were put in to investigate the security of customized Android firmware. However, most of the previous works focus on designing efficient analysis tools or analyzing particular aspects of the firmware. There still lacks a panoramic view of Android firmware ecosystem security and the corresponding understandings based on large-scale firmware datasets. In this work, we made a large-scale comprehensive measurement of the Android firmware ecosystem security. Our study is based on 8,325 firmware images from 153 vendors and 813 Android-related CVEs, which is the largest Android firmware dataset ever used for security measurements. In particular, our study followed a series of research questions, covering vulnerabilities, patches, security updates, and pre-installed apps. To automate the analysis process, we designed a framework, <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AndScanner+</small> , to complete firmware crawling, firmware parsing, patch analysis, and app analysis. Through massive data analysis and case explorations, several interesting findings are obtained. For example, the patch delay and missing issues are widespread in Android firmware images, say 31.4% and 5.6% of all images, respectively. The latest images of several phones still contain vulnerable pre-installed apps, and even the corresponding vulnerabilities have been publicly disclosed. In addition to data measurements, we also explore the causes behind these security threats through case studies and demonstrate that the discovered security threats can be converted into exploitable vulnerabilities. There are 46 new vulnerabilities found by <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AndScanner+</small> , 36 of which have been assigned CVE/CNVD IDs. This study provides much new knowledge of the Android firmware ecosystem with a deep understanding of software engineering security practices.

Tissue characterization of benign cardiac tumors by cardiac magnetic resonance imaging, a review of core imaging protocol and benign cardiac tumors.

Generally, cardiac masses are initially suspected on routine echocardiography. Cardiac magnetic resonance (CMR) imaging is further performed to differentiate tumors from pseudo-tumors and to characterize the cardiac masses based on their appearance on T1/T2-weighted images, detection of perfusion and demonstration of gadolinium-based contrast agent uptake on early and late gadolinium enhancement images. Further evaluation of cardiac masses by CMR is critical because unnecessary surgery can be avoided by better tissue characterization. Different cardiac tissues have different T1 and T2 relaxation times, principally owing to different internal biochemical environments surrounding the protons. In CMR, the signal intensity from a particular tissue depends on its T1 and T2 relaxation times and its proton density. CMR uses this principle to differentiate between various tissue types by weighting images based on their T1 or T2 relaxation times. Generally, tumor cells are larger, edematous, and have associated inflammatory reactions. Higher free water content of the neoplastic cells and other changes in tissue composition lead to prolonged T1/T2 relaxation times and thus an inherent contrast between tumors and normal tissue exists. Overall, these biochemical changes create an environment where different cardiac masses produce different signal intensity on their T1- weighted and T2- weighted images that help to discriminate between them. In this review article, we have provided a detailed description of the core CMR imaging protocol for evaluation of cardiac masses. We have also discussed the basic features of benign cardiac tumors as well as the role of CMR in evaluation and further tissue characterization of these tumors.

Investigation and optimization of PET-guided SPECT reconstructions for improved radionuclide therapy dosimetry estimates.

To investigate and optimize the SPECTRE (Single Photon Emission Computed Theranostic REconstruction) reconstruction approach, using the hybrid kernelised expectation maximization (HKEM) algorithm implemented in the software for tomographic image reconstruction (STIR) software library, and to demonstrate the feasibility of performing algorithm exploration and optimization in 2D. Optimal SPECTRE parameters were investigated for the purpose of improving SPECT-based radionuclide therapy (RNT) dosimetry estimates. Using the NEMA IEC body phantom as the test object, SPECT data were simulated to model an early and late imaging time point following a typical therapeutic dose of 8 GBq of 177Lu. A theranostic 68Ga PET-prior was simulated for the SPECTRE reconstructions. The HKEM algorithm parameter space was investigated for SPECT-unique and PET-SPECT mutual features to characterize optimal SPECTRE parameters for the simulated data. Mean and maximum bias, coefficient of variation (COV %), recovery, SNR and root-mean-square error (RMSE) were used to facilitate comparisons between SPECTRE reconstructions and OSEM reconstructions with resolution modelling (OSEM_RM). 2D reconstructions were compared to those performed in 3D in order to evaluate the utility of accelerated algorithm optimization in 2D. Segmentation accuracy was evaluated using a 42% fixed threshold (FT) on the 3D reconstructed data. SPECTRE parameters that demonstrated improved image quality and quantitative accuracy were determined through investigation of the HKEM algorithm parameter space. OSEM_RM and SPECTRE reconstructions performed in 2D and 3D were qualitatively and quantitatively similar, with SPECTRE showing an average reduction in background COV % by a factor of 2.7 and 3.3 for the 2D case and 3D case respectively. The 42% FT analysis produced an average % volume difference from ground truth of 158% and 26%, for the OSEM_RM and SPECTRE reconstructions, respectively. The SPECTRE reconstruction approach demonstrates significant potential for improved SPECT image quality, leading to more accurate RNT dosimetry estimates when conventional segmentation methods are used. Exploration and optimization of SPECTRE benefited from both fast reconstruction times afforded by first considering the 2D case. This is the first in-depth exploration of the SPECTRE reconstruction approach, and as such, it reveals several insights for reconstructing SPECT data using PET side information.

Association between left ventricular strain and fibrosis in severe aortic regurgitation with preserved ejection fraction: a magnetic resonance and histology study

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Institutional Grant Na Homolce Hospital Background The presence and extent of myocardial fibrosis are associated with poor outcomes in patients with severe aortic regurgitation. In the present study, we tested a correlation between left ventricular (LV) strain derived by using feature-tracking cardiac magnetic resonance (MRI) and diffuse myocardial fibrosis percentage (DMF%) at quantitative histology. Methods A study population included 23 patients (age 51 ± 12 years, 78% males) who underwent perioperative myocardial biopsy during aortic valve surgery for severe aortic regurgitation and who had a satisfactory pre-surgery MRI. Myocardial specimens obtained with a deep needle technique from the basal interventricular septum were stained with picrosirius red, digitalized, and analyzed using Image J software by a pathologist blinded to imaging findings. The DMF% was calculated as a ratio of the total collagen content to the total area. MRI-derived global longitudinal-(GLS), circumferential- (GCS), and radial (GRS) strain, as well as their ratio to heart rate and systolic blood pressure, were assessed using a feature-tracking technique by a certified imager blinded to histological analysis. Results Compared to normal values, all patients showed increased DMF% (19 ± 9%) and decreased GLS (15 ± 2%) despite preserved LV ejection fraction (64 ± 7%). Out of all the imaging parameters, only GLS/heart rate ratio, GCS/heart rate ratio and extracellular volume fraction showed a significant correlation with DMF% (Table 1, Figure 1). In contrast, GLS and GCS only tended to correlate with DMF%. The remaining parameters including GRS did not show a significant association. Patients with focal midwall scar in late gadolinium enhancement imaging (n=8, 35%), which was mainly localized in the basal septum, had similar GLS as than patients without focal scar (14.5±2.3 vs 15.3±2.3, p = 0.768). Conclusions Feature-tracking-derived ratios of LV GLS and GCS over heart rate are the most promising indices for non-invasive assessment of diffuse myocardial fibrosis in severe aortic regurgitation with preserved ejection fraction. Figure 1 Legend Correlation of a GLS/HR ratio 1A) and GLS 1B) with diffuse myocardial fibrosis %. Myocardial histology stained with Picrosirius red (collagen fibers are in red).

Use of artificial intelligence to automatically predict the optimal patient-specific inversion time for late gadolinium enhancement imaging. Tool development and clinical validation

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This research was partly funded by the Italian Ministry of Health Introduction With the worldwide diffusion of cardiac magnetic resonance (CMR), demand on image quality has grown. CMR late gadolinium enhancement (LGE) imaging provides critical diagnostic and prognostic information, and guides management. The identification of optimal Inversion Time (TI), a time-sensitive parameter closely linked to contrast kinetics, is pivotal for correct myocardium nulling. However, determining the optimal TI can be challenging in some diseases and for less experienced operators. Purpose To develop and test an artificial intelligence tool to automatically predict the personalised optimal TI in LGE imaging. Methods The tool, named THAITI, consists of a Random Forest regression model. It considers, as input parameters, patient-specific TI determinants (age, gender, weight, height, kidney function, heart rate) and CMR scan-specific TI determinants (B0, contrast type and dose, time elapsed from contrast injection). THAITI was trained on 219 patients (3585 images) with mixed conditions who underwent CMR (1.5T; Gadobutrol; averaged, MOCO, free-breathing true-FISP IR [1]) for clinical reasons. The dataset was split with a 90–10 policy: 90% of data for training, and 10% for testing. THAITI’s hyperparameters were optimised by embedding k-fold cross validation into an evolutionary computation algorithm, and the best performing model was finally evaluated on the test set. A graphical user interface was also developed. Clinical validation was performed on 55 consecutive patients, randomised to experimental (THAITI-set TI) vs control (operator-set TI) group. Image quality was assessed blindly by 2 independent experienced operators by a 4-points Likert scale, and by means of the contrast/enhancement ratio (CER) (i.e., signal intensity of enhanced/remote myocardium ratio). Results In the testing set, the TI predicted by THAITI differed from the ground truth by ≥ 5ms in 16% of cases. At clinical validation, myocardial nulling quality did not differ between the experimental vs the control group either by CER or visual assessment, with an overall "optimal" or "good" nulling in 96% vs 93%, respectively. Conclusions Using main determinants of contrast kinetics, THAITI efficiently predicted the optimal TI for CMR-LGE imaging. The tool works as a stand-alone on laptops/mobile devices, not requiring adjunctive scanner technology and thus has great potential for diffusion, including in small or recently opened CMR services, and in low-resource settings. Additional development is ongoing to increase generalisability (multi-vendor, multi-sequence, multi-contrast) and to test its potential to further improve CMR-LGE image quality and reduce the need for repeated imaging for inexperienced operators. Figure 1. Top: THAITI interface. Bottom: examples of experimental group CMR-LGE imaging. Table 1. Control vs experimental group. Data expressed as absolute number (%), mean ± SD, median [IQR]. ⧧ T-test; * Chi-square.

Optimal timing of late gadolinium enhancement imaging in patients undergoing CMR for suspected pericarditis: the later the better?

Abstract Funding Acknowledgements Type of funding sources: None. Background Pericarditis is frequently encountered in daily clinical practice and accounts for about 5% of chest pain hospital admissions [1]. Although the diagnosis of pericarditis can be established by clinical criteria, cardiovascular magnetic resonance (CMR) imaging is increasingly used to evaluate concomitant myocardial involvement and/or to exclude other disease entities. Besides well-known morphologic findings like pericardial effusion, thickening or adhesion, pericardial late gadolinium enhancement (LGE) imaging has been demonstrated to be the most sensitive surrogate of pericarditis [2]. Purpose While there is a lot of data regarding the optimal timing of LGE for the detection of myocardial damage, optimal timing of LGE for the detection of pericarditis is unknown. In the recent advent of rapid high-throughput CMR protocols, high diagnostic accuracy needs to be maintained not only for myocardial diseases, but also for the assessment of the pericardium. Methods We present a case series comparing pericardial contrast enhancement in rapid routine LGE images versus LGE images acquired following a longer waiting time after Gadolinium injection (gadoteridol). Results After a longer than rapid clinical routine waiting time, we observed more prominent pericardial signal enhancement in the setting of pericarditis. This effect is most likely explained by different pericardial Gadolinium distribution kinetics compared to the myocardium. Conclusion Consequently, this observation should be taken into account when imaging patients with suspected pericarditis and may warrant further evaluation. Figure: Routine LGE timing (top row) versus delayed LGE timing (bottom row) in 4 patients with pericarditis undergoing CMR Exemplary LGE images in the top row were acquired routinely after ∼10 min. from contrast administration (0,15mmol/Kg), whereas same LGE slices in the bottom row were additionally acquired after a delayed waiting time (∼20 min.) from contrast injection (0,15mmol/Kg). Pericardial LGE was more prominent in delayed LGE imaging compared to routine LGE imaging.