Scanning Protocol Research Articles

Representative Organ Doses from Computed Tomography (CT) Exams from a Large International Registry.

Estimation of absorbed organ doses used in computed tomography (CT) using time-intensive Monte Carlo simulations with virtual patient anatomic models is not widely reported in the literature. Using the library of computational phantoms developed by the University of Florida and the National Cancer Institute, we performed Monte Carlo simulations to calculate organ dose values for 9 CT categories representing the most common body regions and indications for imaging (reflecting low, routine, and high radiation dose examinations), stratified by patient age (in children) and effective diameter (in adults, using "diameter" as a measure of patient size). Our sample of 559,202 adult and 103,423 pediatric CT examinations was prospectively assembled between 2015-2020 from 156 imaging facilities from 27 healthcare organizations in 20 U.S. states and 7 countries in the University of California San Francisco International CT Dose Registry. Organ doses varied by body region and exam type. For example, the mean brain dose associated with head CT was 20 mGy [standard deviation (SD) 14] for head low dose, 46 mGy (SD 21) for head routine dose, and 64 mGy (SD 31) for head high dose scan protocols. The mean colon doses associated with abdomen and pelvis CT were 19 mGy (SD 12), 32 mGy (SD 28), and 69 mGy (SD 42) for low, routine, and high dose examinations, respectively. Organ doses in general varied modestly by patient diameter, and for many categories the organ doses among the largest quartile of patients were no more than 10% higher than doses in the smallest quartile. For example, for abdomen and pelvis high dose, the colon dose increased from 67 to 74 mGy from the smallest to the largest patients (10% increase). With few exceptions, pediatric organ doses also varied relatively little by patient age, except for the youngest children who, on average, had higher organ doses. Thyroid dose, however, tended to increase with age in neck or cervical spine and chest CT. Overall, the highest organ doses were to the skin, thyroid, brain, and eye lens. Mean organ doses differ substantially by site. The organ dose values included in this report are derived from empirical clinical exams and offer useful, representative values. Large inter-site variations demonstrate areas for radiation dose reduction.

Establishment of baseline size-specific dose estimate (SSDE) for paediatric head computed tomography (CT) examinations

BackgroundIn recent times, size-specific dose estimate (SSDE) has been the ideal metric for accurate estimation of individual patient doses in computed tomography (CT) examinations. The objective of this study was to estimate patient radiation doses based on SSDE and the water-equivalent diameter (DW) as an effect tool for dose optimization in paediatric head CT at two facilities in Tamale Metropolis, in the northern region of Ghana. This is a preliminary retrospective study conducted on 57 paediatric patients (comprising 32 males and 25 females), aged newborns to 16 years old, who underwent head CT examinations. Patient head sizes were determined in terms DW, which was calculated by manual contouring the circumference of the CT images excluding the background to measure the region of interest (ROI) using the mid-slice axial CT images. SSDE was calculated as the product of CTDIvol and the size-specific conversion coefficients (CTDIvol, 16 to SSDE) obtained from the American Association of Physicists in Medicine (AAPM) Report 293.ResultsAt facility ‘A’, the median SSDE values for patients, aged 3 months to 1 year, 1 to 6 years, and older than 6 years were 46.1 mGy, 39.6 mGy, and 48.2 mGy, respectively. The corresponding CTDIvol values were 42.3 mGy, 39.1 mGy, and 51.7 mGy. Facility ‘B’ reported median SSDE values of 36.0, 39.2, and 43.8 mGy, with corresponding CTDIvol values of 28.7, 39.8, and 46.9 mGy for the same age categories. For all age groups, the two facilities showed significant differences in SSDE values (44.72 mGy vs. 39.77 mGy, p = 0.009) and CTDIvol values (45.72 mGy vs. 40.60 mGy, p = 0.03). Some of the age group doses were up to 25.3% in CTDIvol and 25.8% in SSDE higher than those found in published data.ConclusionsThe SSDEs estimated showed significant variations between the two facilities, indicating a possible variability of scan protocols for paediatric head CT examinations. The SSDEs obtained in this study could be useful for optimization of paediatric routine head CT examinations.

Different scanning protocol to assess left atrial appendage thrombus in patients with atrial fibrillation by cardiovascular computed tomography

To investigate whether we can rule out the left atrial appendage (LAA) thrombus in patients with atrial fibrillation (AF) using different scanning protocol by Cardiovascular Computed Tomography (CCT). We retrospectively reviewed the CCT images of 138 patients with AF to assess LAA thrombus. Patients with no thrombosis diagnosed by preoperative CCT should be confirmed using intraoperative findings as the reference standard. Patients diagnosed with thrombosis were then compared with TEE examination. Different CT scanning protocol were used to assess LAA thrombus according to individual differences. In 126 cases, there was no thrombus in the LAA evaluated by preoperative CCT, and it was confirmed in the subsequent radiofrequency operation. CCT has the accuracy of 100% in confirming the absence of thrombus in the LAA. Twelve thrombi were detected by CCT, eleven thrombi were detected by TEE. Only one patient had different results between CCT and TEE. We could use different CT scanning protocol to rule out LAA thrombus according to individual differences. In some special patients, LAA thrombus can be evaluated by CCT instead of TEE.

Diagnostic capabilities of cardiac computed tomography in the preoperative diagnosis of hypertrophic cardiomyopathy

BACKGROUND: A comprehensive approach to studying hypertrophic cardiomyopathy with diagnostic equipment and the latest scanning methods will ensure quality control and effective treatment of patients with this condition. The implementation of innovative technologies and computer calculation using next-generation scanners may become relevant and promising in studying various phenotypes of left ventricular remodeling in combination with abnormalities of the chordopapillary apparatus of the mitral valve and myocardial structure. AIM: To examine the diagnostic capabilities of computed tomography in the preoperative examination of various hypertrophic cardiomyopathy phenotypes. MATERIALS AND METHODS: The retrospective data analysis included 47 patients with hypertrophic cardiomyopathy (mean age, 52±7 full years) before surgical correction. computed tomography was performed using our protocol with automatic bolus tracking in the left atrium with a 90 HU threshold and biphasic contrast injection to assess the heart chambers and coronary arteries anatomy and mitral valve morphology. Moreover, to assess myocardial structure remodeling, iodine dual-energy computed tomography maps obtained with delayed contrast enhancement were analyzed. All patients with hypertrophic cardiomyopathy were classified by morphological types. The anatomy of chordopapillary apparatus was evaluated in each case. RESULTS: This study demonstrated variability in hypertrophic cardiomyopathy phenotypes, which were conventionally divided into five morphological categories, but not restricted by them. Among the patients, 26 (55%) had diffuse septum hypertrophic cardiomyopathy, 5 (11%) had midventricular hypertrophic cardiomyopathy, 2 (4%) had midventricular obstruction and apical aneurysm, 8 (18%) had focal basal septum hypertrophic cardiomyopathy, 4 (8%) had concentric hypertrophic cardiomyopathy, and the remaining 4 (8%) had apical hypertrophic cardiomyopathy. Most patients were diagnosed with chordopapillary abnormalities of the mitral valve, categorized by papillary muscle number and position, and the ratio of chords to muscles. In 10 (21%) patients, data on the myocardial bridge of a coronary artery were obtained, whereas 3 (14%) of them had dynamic stenosis. All patients had focal iodine uptake on dual-energy computed tomography maps. An extracellular volume increase was observed in 10 out of 13 (76%) patients. As shown by dual-energy computed tomography, the mean extracellular volume of the left ventricular myocardium was 30.58% (95% confidence interval, 27–34%). CONCLUSION: Our scanning protocols developed with computed tomography scanners of various generations enable to evaluate the specific morphological patterns of hypertrophic cardiomyopathy in a single study and provide a detailed interpretation of the geometry of cardiac valves and chambers, left ventricular function, state of the coronary bed, and structural changes of the left ventricular myocardium.

Comprehensive assessment of nonuniform image quality: Application to imaging near metal.

Comprehensive assessment of image quality requires accounting for spatial variations in (i) intensity artifact, (ii) geometric distortion, (iii) signal-to-noise ratio (SNR), and (iv) spatial resolution, among other factors. This work presents an ensemble of methods to meet this need, from phantom design to image analysis, and applies it to the scenario of imaging near metal. A modular phantom design employing a gyroid lattice is developed to enable the co-registered volumetric quantitation of image quality near a metallic hip implant. A method for measuring spatial resolution by means of local point spread function (PSF) estimation is presented and the relative fitness of gyroid and cubic lattices is examined. Intensity artifact, geometric distortion, and SNR maps are also computed. Results are demonstrated with 2D-FSE and MAVRIC-SL scan protocols on a 3T MRI scanner. The spatial resolution method demonstrates a worst-case error of 0.17 pixels for measuring in-plane blurring up to 3 pixels (full width at half maximum). The gyroid outperforms a cubic lattice design for the local PSF estimation task. The phantom supports four configurations toggling the presence/absence of both metal and structure with good spatial correspondence for co-registered analysis of the four quality factors. The marginal scan time to evaluate one scan protocol amounts to five repetitions. The phantom design can be fabricated in 2 days at negligible material cost. The phantom and associated analysis methods can elucidate complex image quality trade-offs involving intensity artifact, geometric distortion, SNR, and spatial resolution. The ensemble of methods is suitable for benchmarking imaging performance near metal.

Additive manufacturing trueness and internal fit of crowns in resin modified with a commercially available ceramic composite concentrate

Inorganic fillers can be incorporated into additively manufactured (AM) resins to improve their properties, and a ceramic composite concentrate has been recently marketed for this purpose. However, knowledge on the printability of AM resins modified with this concentrate is lacking. The purpose of this in vitro study was to evaluate the manufacturing trueness and internal fit of AM crowns in a dental resin modified with a commercially available ceramic composite concentrate. A maxillary right first molar typodont tooth was prepared and digitized to design a crown in standard tessellation language (STL) format. This STL file was used to fabricate a total of 30 AM crowns, 10 with a resin with no fillers for interim restorations (AM-I), 10 AM-I resin incorporated with ceramic composite concentrate (AM-IR), and 10 with a ceramic-filled resin intended for definitive restorations (AM-D). The modification of the AM-IR resin was performed by mechanically mixing 30wt% of a commercially available ceramic composite concentrate into AM-I. An intraoral scanner was used to digitize all crowns, which were then seated on the prepared typodont abutment and rescanned. The manufacturing trueness of each crown was measured in 4 regions (overall, external, intaglio, and marginal) and reported with root mean square (RMS) estimates. The internal gaps were calculated by using a triple scan protocol. The intaglio surface deviations were assessed with the Kruskal-Wallis and Dunn tests, while the remaining data were analyzed with the 1-way analysis of variance and Tukey honestly significant difference tests (α=.05). AM-IR had the highest overall and external RMS and had higher intaglio RMS than AM-D (P≤.001). AM-I had the lowest marginal RMS (P≤.002). AM-IR had the highest average gap values (P≤.027). AM-IR crowns mostly had lower trueness and high internal gaps. However, the differences among the tested materials in fabrication trueness and average gap values were small, and internal gaps were within the previously reported thresholds.

Usage of Magnetic Resonance Imaging-Based Texture Analysis Features in Discrimination of Benign and Malignant Sinonasal Tumors

Aim: The objective of this study was to differentiate between benign and malignant sinonasal tumors using magnetic resonance imaging (MRI)-based texture analysis features. Materials and Method: Histopathologically proven benign or malignant sinonasal tumor patients were included in the study from MRI examinations performed between January 2013 and December 2020. Inclusion criteria included a tumor size of at least 1 cm and preoperative magnetic resonance imaging with axial T1W, axial fat-suppressed T2W, and axial T1W postcontrast sequences. After the images were transferred to a dedicated workstation, texture analysis calculations were performed. Differences between benign and malignant groups were compared. Results: The mean age of 37 patients (8 female, 29 male) included in the study was 50.8 ± 21.9 years. In our study, we found no statistically significant difference between malignant and benign sinonasal tumors in nine tissue analysis parameters obtained by MRI. Conclusion: MRI-based texture analysis needs identical MRI protocols for evaluating tumors. MRI-based texture analysis is not a useful diagnostic tool to discriminate between benign and malignant sinonasal tumors when specific pathologic types are not selected and scanning protocols are not identical.

Point-of-care ultrasound for the diagnosis of distal forearm fractures in children and adolescents: a scoping review.

Distal forearm fractures are the most common pediatric fractures. Currently, the diagnostic reference standard is X-ray. However, there is growing evidence that point-of-care ultrasound can be used for the diagnosis of distal forearm fractures in children and adolescents with good accuracy. The objective of this scoping review was to explore the current evidence for the use of ultrasound for the diagnosis of pediatric distal forearm fractures and to identify the gaps in the literature for further research. We performed a scoping review searching on the following databases PubMed, MEDLINE, SCOPUS, EMBASE, and ClinicalTrials.gov. The main review question was "What is the evidence for using ultrasound to diagnose distal forearm fractures in patients < 18years old?" All types of studies, including randomized clinical trials and prospective and retrospective observational studies (case-control, cohort, and cross-sectional studies, case series) were included. Twenty-three articles were included in the scoping review; only two articles were from a single randomized controlled trial. Our scoping review found high sensitivity (91.5-99.5%) and specificity (85-99.5%) of POCUS for distal forearm fracture diagnosis. All studies used a linear ultrasound probe, with an upper range frequency ranging from 5 to 15MHz and typically used a six-view scanning protocol. The duration of the procedure was only a few minutes, and pain associated with ultrasound was usually mild. When compared with X-ray, an ultrasound first approach shortened the length of stay by an average of 15min per participant. Conclusions: The evidence suggests that ultrasound can be used for the diagnosis of clinically nondeformed distal forearm fractures in children and adolescents by a variety of practitioners. However, the current gaps in the literature include its translation into clinical practice and its cost-effectiveness.

Advancing clinical MRI exams with artificial intelligence: Japan's contributions and future prospects.

In this narrative review, we review the applications of artificial intelligence (AI) into clinical magnetic resonance imaging (MRI) exams, with a particular focus on Japan's contributions to this field. In the first part of the review, we introduce the various applications of AI in optimizing different aspects of the MRI process, including scan protocols, patient preparation, image acquisition, image reconstruction, and postprocessing techniques. Additionally, we examine AI's growing influence in clinical decision-making, particularly in areas such as segmentation, radiation therapy planning, and reporting assistance. By emphasizing studies conducted in Japan, we highlight the nation's contributions to the advancement of AI in MRI. In the latter part of the review, we highlight the characteristics that make Japan a unique environment for the development and implementation of AI in MRI examinations. Japan's healthcare landscape is distinguished by several key factors that collectively create a fertile ground for AI research and development. Notably, Japan boasts one of the highest densities of MRI scanners per capita globally, ensuring widespread access to the exam. Japan's national health insurance system plays a pivotal role by providing MRI scans to all citizens irrespective of socioeconomic status, which facilitates the collection of inclusive and unbiased imaging data across a diverse population. Japan's extensive health screening programs, coupled with collaborative research initiatives like the Japan Medical Imaging Database (J-MID), enable the aggregation and sharing of large, high-quality datasets. With its technological expertise and healthcare infrastructure, Japan is well-positioned to make meaningful contributions to the MRI-AI domain. The collaborative efforts of researchers, clinicians, and technology experts, including those in Japan, will continue to advance the future of AI in clinical MRI, potentially leading to improvements in patient care and healthcare efficiency.

Accuracy of different maxillomandibular relationship recording techniques in the edentulous maxillary arch.

This study investigated the effect of three digital bite registration techniques on the accuracy of intraoral scanning in maxillary edentulous and mandibular dentate arches. Maxillary edentulous and mandible fully dentate models were created. Four dental implants were placed in the maxilla, fitted with scan bodies, and reference scans were obtained using a Nikon Altera 10.7.6 scanner. Digital impressions were acquired 10 times for each model using a Trios 4 intraoral scanner. Three different digital bite records were collected for each pair of mandible and maxilla scans. The first one was a bite record without additional material (WSB), the second utilized a silicone index between the models (WSB silicone), and the third followed a pre-preparation scanning protocol (Pre-PREP). The data was exported in standard tessellation language (STL) format, which was assessed for trueness and precision using statistical analysis. According to mean trueness values, WSB exhibited the lowest value, 173 µm, followed by WSB silicone 242 µm and Pre-PREP 620 µm. The differences were significant only when comparing Pre-PREP to WSB and Pre-PREP to WSB silicone (p <0.05). Regarding precision, WSB demonstrated a mean value of 171.5 µm, followed by WSB silicone with 213.8 µm, and Pre-PREP with 222.2 µm with no significant difference between the groups. The presence of interarch bite registration material adversely affected interocclusal record accuracy, while WSB silicone presented a suitable substitute for WSB.

The Effect of Low-Dose CT Protocols on Shoulder Model-Based Tracking accuracy Using Biplane Videoradiography.

Model-based tracking is being increasingly used to quantify shoulder kinematics and typically employs computed tomography (CT) to create the 3D bone volumes, which adds to the total radiation exposure. Lower-dose CT protocols may be possible given the contrast between bone and the surrounding soft tissues. The purpose of this study was to describe the dose-accuracy tradeoff between low-dose CT scans and the kinematic tracking accuracy of the humerus, scapula, and clavicle when tracked using an intensity-based registration algorithm. Three fresh-frozen cadavers consisting of the torso and bilateral shoulders were tested. The CT protocols investigated included a full-dose protocol and 4 experimental low-dose protocols that modulated x-raytube current and peak voltage. Bead-based tracking (i.e., radiostereometric analysis) served as the reference standard to which model-based tracking results were compared. Accuracy was described in terms of both segmental (humerus, scapula, and clavicle) and joint (glenohumeral, acromioclavicular) kinematics using root-mean-square (RMSE), bias, precision, and worst-case errors. The low-dose CT scans resulted in an average dose reduction of 70.6-92.8%. RMSEs tended to increase as CT dose decreased with average glenohumeral errors increasing from 0.5° and 0.6 mm to 0.6° and 0.6 mm between the highest and lowest-dose protocols, and average acromioclavicular errors increasing from 0.6° and 0.8 mm to 0.7° and 0.9 mm. However, the difference in joint kinematic errors between the highest and lowest-dose CT scanning protocols was generally small (≤0.3°, ≤ 0.1 mm). It is possible to substantially reduce the CT dose associated with shoulder motion analysis using biplane videoradiography without significantly impacting data fidelity.

Unbiased and reproducible liver MRI-PDFF estimation using a scan protocol-informed deep learning method.

To estimate proton density fat fraction (PDFF) from chemical shift encoded (CSE) MR images using a deep learning (DL)-based method that is precise and robust to different MR scanners and acquisition echo times (TEs). Variable echo times neural network (VET-Net) is a two-stage framework that first estimates nonlinear variables of the CSE-MR signal model, to posteriorly estimate water/fat signal components using the least-squares method. VET-Net incorporates a vector with TEs as an auxiliary input, therefore enabling PDFF calculation with any TE setting. A single-site liver CSE-MRI dataset (188 subjects, 4146 axial slices) was considered, which was split into training (150 subjects), validation (18), and testing (20) subsets. Testing subjects were scanned using several protocols with different TEs, which we then used to measure the PDFF reproducibility coefficient (RDC) at two regions of interest (ROIs): the right posterior and left hepatic lobes. An open-source multi-site and multi-vendor fat-water phantom dataset was also used for PDFF bias assessment. VET-Net showed RDCs of 1.71% and 1.04% on the right posterior and left hepatic lobes, respectively, across different TEs, which was comparable to a reference graph cuts-based method (RDCs = 1.71% and 0.86%). VET-Net also showed a smaller PDFF bias (-0.55%) than graph cuts (0.93%) when tested on a multi-site phantom dataset. Reproducibility (1.94% and 1.59%) and bias (-2.04%) were negatively affected when the auxiliary TE input was not considered. VET-Net provided unbiased and precise PDFF estimations using CSE-MR images from different hardware vendors and different TEs, outperforming conventional DL approaches. Question Reproducibility of liver PDFF DL-based approaches on different scan protocols or manufacturers is not validated. Findings VET-Net showed a PDFF bias of -0.55% on a multi-site phantom dataset, and RDCs of 1.71% and 1.04% at two liver ROIs. Clinical relevance VET-Net provides efficient, in terms of scan and processing times, and unbiased PDFF estimations across different MR scanners and scan protocols, and therefore it can be leveraged to expand the use of MRI-based liver fat quantification to assess hepatic steatosis.

Review of the role of ultrasound in assessing plasma leakage in dengue fever and a proposed scanning protocol

AbstractBackgroundThe clinical course of dengue can range from mild to severe and predicting the course can be challenging. The World Health Organisation (WHO) recommends prognostication via the presence of warning signs, to aid in disposition and management. Plasma leakage is a key warning sign in dengue, and ultrasound can be utilised as a screening tool.ObjectivesThe objectives were to describe the literature on the use of ultrasound in dengue, summarise the findings, and propose a standardised point‐of‐care ultrasound protocol.MethodsWe reviewed the current literature on the role of ultrasound in dengue and its key features.ResultsUltrasound is a useful tool in the evaluation of patients with dengue and has been shown to be able to detect plasma leakage even prior to clinical and laboratory findings. In particular, gallbladder wall thickening is an early sign that can aid the clinician in prognosticating patients.ConclusionDetecting plasma leakage early with ultrasonography can help the clinician determine appropriate disposition and management. We propose a standardised point‐of‐care ultrasound protocol (FASD) for early detection of plasma leakage in dengue, in the routine care of dengue patients.

Implementing verifiable oncological imaging by quality assurance and optimization (i‑Violin) : Protocol for aEuropean multicenter study.

Advanced imaging techniques play apivotal role in oncology. Alarge variety of computed tomography (CT) scanners, scan protocols, and acquisition techniques have led to awide range in image quality and radiation exposure. This study aims at implementing verifiable oncological imaging by quality assurance and optimization (i-Violin) through harmonizing image quality and radiation dose across Europe. The 2‑year multicenter implementation study outlined here will focus on CT imaging of lung, stomach, and colorectal cancer and include imaging for four radiological indications: diagnosis, radiation therapy planning, staging, and follow-up. Therefore, 480 anonymized CT data sets of patients will be collected by the associated university hospitals and uploaded to arepository. Radiologists will determine key abdominopelvic structures for image quality assessment by consensus and subsequently adapt apreviously developed lung CT tool for the objective evaluation of image quality. The quality metrics will be evaluated for their correlation with perceived image quality and the standardized optimization strategy will be disseminated across Europe. The results of the outlined study will be used to obtain European reference data, to build teaching programs for the developed tools, and to create aculture of optimization in oncological CT imaging. The study protocol and rationale for i‑Violin, aEuropean approach for standardization and harmonization of image quality and optimization of CT procedures in oncological imaging, is presented. Future results will be disseminated across all EU member states, and i‑Violin is thus expected to have asustained impact on CT imaging for cancer patients across Europe.

Kinetic Analysis and Metabolism of Poly(Adenosine Diphosphate-Ribose) Polymerase-1-Targeted 18F-Fluorthanatrace PET in Breast Cancer.

The poly(adenosine diphosphate-ribose) polymerase inhibitors (PARPi) have demonstrated efficacy in ovarian, breast, and prostate cancers, but current biomarkers do not consistently predict clinical benefit. 18F-fluorthanatrace (18F-FTT) is an analog to rucaparib, a clinically approved PARPi, and is a candidate biomarker for PARPi response. This study intends to characterize 18F-FTT pharmacokinetics in breast cancer and optimize image timing for clinical trials. A secondary aim is to determine whether 18F-FTT uptake in breast cancer correlates with matched frozen surgical specimens as a reference standard for PARP-1 protein. Methods: Thirty prospectively enrolled women with a new diagnosis of breast cancer were injected with 18F-FTT and imaged dynamically 0-60 min after injection over the chest, with an optional static scan over multiple bed positions starting around 70 min. Kinetic analysis of lesion uptake was performed using blood-pool activity with population radiometabolite corrections. Normal breast and normal muscle reference tissue models were compared with PARP-1 protein expression in 10 patients with available tissue. Plasma radiometabolite concentrations and uptake in tumor and normal muscle were investigated in mouse xenografts. Results: Pharmacokinetics of 18F-FTT were well fit by Logan plot reference region models of reversible binding. However, fits of 2-tissue compartment models assuming negligible metabolite uptake were unstable. Rapid metabolism of 18F-FTT was demonstrated in mice, and similar uptake of radiometabolites was found in tumor xenografts and normal muscle. Tumor 18F-FTT distribution volume ratios relative to normal muscle reference tissue correlated with tissue PARP-1 expression (P < 0.02, n = 10). The tumor-to-normal muscle ratio from a 5-min frame between 50 and 60 min after injection, a potential static scan protocol, closely corresponded to the distribution volume ratio relative to normal muscle and correlated to PARP-1 expression (P < 0.02, n = 10). Conclusion: This study of PARPi analog 18F-FTT showed that uptake kinetics invivo corresponded to expression of PARP-1 and that 18F-FTT quantitation is influenced by radiometabolites that are increasingly present late after injection. Radiometabolites can be controlled by using optimal image acquisition timing or normal muscle reference tissue modeling in dynamic imaging or a tumor-to-normal muscle ratio. Optimal image timing for tumor-to-normal muscle quantification in humans appears to be between 50 and 60 min after injection. Therefore, a clinically practical static imaging protocol commencing 45-55 min after injection may sufficiently balance 18F-FTT uptake with background clearance and radiometabolite interference for quantitative interpretation of PARP-1 expression invivo.

The role of cardiac magnetic resonance in patients with an angiographically diagnosed SCAD

Abstract Background/Introduction Spontaneous coronary artery dissection (SCAD) characterized by its non-atherosclerotic nature, poses challenges in diagnosis and management. While recent efforts shed light on SCAD's clinical aspects, the specific utility of CMR demands deeper investigation for enhanced diagnosis and patient care. Purpose This study aims to analyze the characteristics of patients with an angiographically diagnosed SCAD, evaluate qualitative and quantitative parameters of baseline CMR and investigate predictors of myocardial injury and the association between CMR parameters and clinical outcome (major adverse cardiac events, MACE). Methods The study is a prospective single-center analysis of 59 patients, presented acutely in our hospital, from March 2018 to November 2023, with an angiographically detected SCAD. CMR was performed after a median of 4 days (IQR 1.5-7) from the acute onset of symptoms. SCAD Types were angiographically categorized according to the Yip-Saw classification. Most patients (71%) were screened for fibromuscular dysplasia (FMD) with a brain MR and at least one contrast-enhanced abdominal vessels investigation (CT or MR). CMR imaging was performed on a clinical 1.5 T Scanner. T1-weighted, T2-weighted turbo-spin-echo (TSE) Black-Blood (BB) and Short-Tau-Inversion-Recovery (STIR) sequences in short-axis orientation were acquired. The scan protocol included standard cine and T1/T2-weighted TSE BB and Mapping sequences. Late gadolinium enhanced (LGE) images were acquired ≏10 min after the contrast injection and were visually assessed for the presence and extension of LGE areas. LGE quantification was assessed semiautomatically. Results 40 (68%) were females. 54(92%) complained of chest pain, in 55 (93%) high-sensitive Troponin T was eleveted (&amp;gt;14 ng/l) and 24 (41%) presented with the clinical picture of STEMI on admission. From an angiographic point of view, the majority (69.5%) were classified as SCAD Type 2 (a+b). Among patients who underwent a proper screening, 7 patients (16%) were diagnosed with FMD. Baseline CMR showed signs of active injury in 81% and LGE in 93% of the population; however, it was often moderate in size (median of LGE segments 3, IQR 2-5). Most patients had a preserved LVEF (55±10%). STEMI presentation is an independent predictor of LGE extension (p=0.02, OddsRatio(95% CI)=7(2-24)). ScadType1 (p=0.01, OR=10( 2-39)) and N°LGE transmural segments &amp;gt;3 (p=0.03, OR=5.4(1.2-25)) were found to be significant predictor of MACE. 6 of the 11 MACEs were SCAD recurrence/progression, and 4 out of these 11 had already shown signs of previous myocardial injury in the baseline CMR. Conclusion(s) This study emphasized the significance of CMR, which may provide further insights into extend of myocardial damage and may aid in patients’ risk stratification.

An artificial intelligence-based landmark model for early detection of aortic stenosis in Cardiac MRI

Abstract Background The utilisation of ratiometric intensity measures from cardiac magnetic resonance imaging (CMR) offers a promising biomarker for the diagnosis of aortic stenosis (AS)[1]. The Ao:LV ratio, an approximation of AS severity, is determined by comparing the relative blood signal intensity in the aorta and left ventricle (LV) within three-chamber (3Ch) cine sequences[1]. In patients with AS, the blood signal intensity of aortic blood above the valve is diminished compared to that within the LV in steady-state free precession (SSFP) 3Ch CMR cine. Although the Ao:LV ratio serves as a reliable indicator of AS severity, manual computation of this ratio may encounter difficulties due to visual obstructions caused by small LV cavities or prominent papillary muscles. Purpose This study aims to leverage artificial intelligence (AI) to automate the Ao:LV ratio analysis from 3Ch SSFP cine images and introduce the Ao:LA (aorta to left atrium) ratio, thus enhancing the diagnostic accuracy for AS severity. Methods Our methodology extends the ratiometric analysis to include both Ao:LV and Ao:LA ratios in three main steps: first, developing an AI-based algorithm for automated detection and tracking of cardiac landmarks; second, using these landmarks to automatically compute regions of interest (ROIs) in the cardiac chambers; and third, training and validating classification models with 5-fold cross-validation to select the most effective for AS severity classification. The final model's performance is assessed on a holdout test set. Data for model training and evaluation were sourced from CMR scans across three hospitals and two scanner types. Results We analysed 220 patients of which 78 patients had no AS and 122 had AS (mild AS, n = 29; moderate AS; n = 35, severe AS; n = 78). Our model yielded high efficacy in classifying AS, particularly in differentiating any grade of AS from a normal classification, which is clinically relevant. The Ao:LA ratio demonstrated a stronger correlation with AS severity class than Ao:LV, suggesting a more reliable biomarker. The proposed model demonstrated robust performance in AS classification, achieving an Area Under the Curve (AUC) of 0.845 in the automated binary classification of AS at any grade. The model exhibited a precision of 0.889, recall of 0.865, and an F1 score of 0.877 on a holdout set. Conclusion By the integration of AI in automating the analysis of CMR images through a novel ratiometric approach that includes Ao:LV and Ao:LA ratios, our model significantly improves the accuracy of early AS detection. This advancement enhances imaging strategies for AS evaluation, promoting more efficient and effective use of cardiac MRI sequences as a diagnostic tool for aortic stenosis. It has the potential to be implemented in real-time scanning protocols as a clinical decision support system.AI-inferred cardiac landmarks.ROC curve delineating AS prediction.

G.O.O.S.E.: Introducing a novel five‐stage structured framework for the early phases of teaching and learning ultrasound

AbstractThe sonography profession faces a critical global workforce shortage, particularly pronounced in Australia, due to insufficient clinical training opportunities and an ageing workforce. The financial burden and increased scan times associated with training exacerbate this issue. Innovative approaches, such as intensive ultrasound courses and pair scanning protocols, have shown promise in addressing these challenges. The GOOSE framework (Get the window, Optimise the view, Optimise the image, Select the image, Explain the findings) offers a structured, step‐by‐step approach to practical sonography training. This framework deconstructs complex ultrasound skills into manageable tasks, optimises cognitive load management, and provides explicit guidance for novice learners. The GOOSE framework is designed to enhance the efficiency of teaching and learning by simplifying complex skills into clear, actionable steps, supported by checklists that guide both instructors and students through the training process. The GOOSE framework offers a systematisation of knowledge transfer that, combined with deliberate practice and structured feedback, ensures learners progressively build their skills with focused, goal‐directed activities. While this model is yet to be validated, initial implementations have shown promising results in improving trainee performance, reducing supervision workload, and standardising instructional methods. This article outlines the principles of the GOOSE framework, its development, and its application in a specialised training facility, proposing it as a standardised model to enhance practical ultrasound education and improve teaching and learning efficiency.

CT imaging using variable helical pitch scanning for lower extremity arterial disease: Reduced contrast medium dose, improved image quality and diagnostic accuracy

ObjectivesThis study aimed to explore the feasibility of reducing contrast medium (CM) volume, improving image quality and diagnostic accuracy using variable helical pitch (VHP) scanning for patients with lower extremity arterial disease (LEAD). Materials and methodsEighty patients who underwent lower extremity CT angiography (CTA) were prospectively enrolled and randomly assigned to either the VHP group (n = 40) or the conventional group (n = 40). Quantitative parameters and qualitative scores were compared between the two groups. Additionally, out of these patients, 72 arteries from 18 patients had DSA as the reference standard, and the diagnostic accuracy for the degree of vessel stenosis was assessed and compared. ResultsIn the VHP group, the contrast volume was significantly lower than in the conventional group (79.55 ± 11.87 mL vs. 89.63 ± 10.03 mL, p < 0.001), showing a reduction of 12.7 %. For all image quality characteristics, scores in VHP group were significantly superior to those in the conventional groups (all p < 0.05). Quantitative analysis revealed that images from the VHP group exhibited superior CT enhancement, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in the anterior tibial arteries (ATA) and dorsali pedis arteries (DPA) compared to the conventional group (all p < 0.001). Moreover, segment-based analysis showed the VHP group had significantly higher positive predictive value (PPV) and accuracy than the conventional group (PPV: 100 % vs. 76.19 %, p = 0.01; accuracy: 100 % vs. 84.38 %, p = 0.01, respectively). ConclusionsThe implementation of the VHP protocol led to a 12.7 % decrease in contrast medium dosage compared to the conventional lower extremity CTA scanning protocol. Furthermore, it improved image quality and diagnostic accuracy, particularly for arteries below the knee.

Chronic active lesions preferentially localize in watershed territories in multiple sclerosis.

Paramagnetic rim lesions (PRLs) are a biomarker of chronic active lesions (CALs), and an important driver of neurological disability in multiple sclerosis (MS). The reason subtending some acute lesions evolvement into CALs is not known. Here we ask whether a relatively lower oxygen content is linked to CALs. In this prospective cross-sectional study, 64 people with multiple sclerosis (PwMS), clinically isolated syndrome and radiologically isolated syndrome underwent a 7.0 Tesla (7 T) brain magnetic resonance imaging (MRI). The scanning protocol included a T2-w fluid-attenuated inversion recovery (FLAIR), and a single echo gradient echo from which susceptibility-weighted imaging (SWI) was derived. WM lesions were identified on the T2-w-FLAIR whilst PRLs were identified on the SWI sequence. T2-lesions were classified as PRLs and rimless lesions (PRLs-). We registered a universal vascular atlas to each subject's T2-w-FLAIR and classified each T2-lesions according to its location into watershed- (ws), non-watershed- (nws), and mixed-lesion (m). Ws-lesions were defined as lesions that were fully located in a region between the territories of two major arteries. Out of 1,975 T2-lesions, 88 (4.5%) were PRLs. Ws-regions had a higher number (p = 0.005) and proportion (p < 0.001) of PRLs- compared to nws-regions. Ws-PRL- were larger compared to nws-ones (p = 0.009). The number (p = 0.043) and proportion (p < 0.001) of PRLs was higher in ws-regions compared to nws-ones. Ws-PRLs were not significantlylarger than nws-ones (p = 0.195). We propose the novel concept of a link between arterial vascularization and chronic activity in MS by demonstrating a preferential localization of CALs in ws-territories.