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Tomography, Volume 9, Issue 3 (June 2023) – 23 articles

Cover Story (view full-size image): Preclinical imaging is increasingly being used in translational cancer research to assess the efficacy of therapeutic strategies, detect and characterize the heterogeneity of tumors, and to validate imaging biomarkers. However, unlike clinical imaging, there are no standard preclinical acquisition protocols nor widely accepted reporting standards. In this work, we describe a consensus of preclinical imaging metadata needs across a range of oncologic preclinical imaging experiment workflows to enable the organization of sustainable database image archives that support queries and computational/statistical analysis. We anticipate that better reporting standards will promote open science, standardization, and reproducibility in preclinical imaging, as well as facilitate integration with clinical imaging arms of co-clinical trials. View this paper
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34 pages, 6268 KiB  
Review
Tips and Tricks in Thoracic Radiology for Beginners: A Findings-Based Approach
by Alessandra Borgheresi, Andrea Agostini, Luca Pierpaoli, Alessandra Bruno, Tommaso Valeri, Ginevra Danti, Eleonora Bicci, Michela Gabelloni, Federica De Muzio, Maria Chiara Brunese, Federico Bruno, Pierpaolo Palumbo, Roberta Fusco, Vincenza Granata, Nicoletta Gandolfo, Vittorio Miele, Antonio Barile and Andrea Giovagnoni
Tomography 2023, 9(3), 1153-1186; https://doi.org/10.3390/tomography9030095 - 14 Jun 2023
Viewed by 4891
Abstract
This review has the purpose of illustrating schematically and comprehensively the key concepts for the beginner who approaches chest radiology for the first time. The approach to thoracic imaging may be challenging for the beginner due to the wide spectrum of diseases, their [...] Read more.
This review has the purpose of illustrating schematically and comprehensively the key concepts for the beginner who approaches chest radiology for the first time. The approach to thoracic imaging may be challenging for the beginner due to the wide spectrum of diseases, their overlap, and the complexity of radiological findings. The first step consists of the proper assessment of the basic imaging findings. This review is divided into three main districts (mediastinum, pleura, focal and diffuse diseases of the lung parenchyma): the main findings will be discussed in a clinical scenario. Radiological tips and tricks, and relative clinical background, will be provided to orient the beginner toward the differential diagnoses of the main thoracic diseases. Full article
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16 pages, 10641 KiB  
Article
Sinogram Inpainting with Generative Adversarial Networks and Shape Priors
by Emilien Valat, Katayoun Farrahi and Thomas Blumensath
Tomography 2023, 9(3), 1137-1152; https://doi.org/10.3390/tomography9030094 - 13 Jun 2023
Cited by 2 | Viewed by 1610
Abstract
X-ray computed tomography is a widely used, non-destructive imaging technique that computes cross-sectional images of an object from a set of X-ray absorption profiles (the so-called sinogram). The computation of the image from the sinogram is an ill-posed inverse problem, which becomes underdetermined [...] Read more.
X-ray computed tomography is a widely used, non-destructive imaging technique that computes cross-sectional images of an object from a set of X-ray absorption profiles (the so-called sinogram). The computation of the image from the sinogram is an ill-posed inverse problem, which becomes underdetermined when we are only able to collect insufficiently many X-ray measurements. We are here interested in solving X-ray tomography image reconstruction problems where we are unable to scan the object from all directions, but where we have prior information about the object’s shape. We thus propose a method that reduces image artefacts due to limited tomographic measurements by inferring missing measurements using shape priors. Our method uses a Generative Adversarial Network that combines limited acquisition data and shape information. While most existing methods focus on evenly spaced missing scanning angles, we propose an approach that infers a substantial number of consecutive missing acquisitions. We show that our method consistently improves image quality compared to images reconstructed using the previous state-of-the-art sinogram-inpainting techniques. In particular, we demonstrate a 7 dB Peak Signal-to-Noise Ratio improvement compared to other methods. Full article
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4 pages, 189 KiB  
Editorial
Imaging in Non-Traumatic Emergencies
by Mariano Scaglione, Salvatore Masala, Francesca Iacobellis, Michele Tonerini, Giacomo Sica, Carlo Liguori, Luca Saba and Stefania Tamburrini
Tomography 2023, 9(3), 1133-1136; https://doi.org/10.3390/tomography9030093 - 12 Jun 2023
Cited by 1 | Viewed by 945
Abstract
“Emergency” is a scenario that every medical professional must face since the first day of her/his career [...] Full article
(This article belongs to the Special Issue Imaging in Non-Traumatic Emergencies)
13 pages, 2984 KiB  
Article
Multiclass Segmentation of Breast Tissue and Suspicious Findings: A Simulation-Based Study for the Development of Self-Steering Tomosynthesis
by Bruno Barufaldi, Yann N. G. da Nobrega, Giulia Carvalhal, Joao P. V. Teixeira, Telmo M. Silva Filho, Thais G. do Rego, Yuri Malheiros, Raymond J. Acciavatti and Andrew D. A. Maidment
Tomography 2023, 9(3), 1120-1132; https://doi.org/10.3390/tomography9030092 - 10 Jun 2023
Viewed by 1375
Abstract
In breast tomosynthesis, multiple low-dose projections are acquired in a single scanning direction over a limited angular range to produce cross-sectional planes through the breast for three-dimensional imaging interpretation. We built a next-generation tomosynthesis system capable of multidirectional source motion with the intent [...] Read more.
In breast tomosynthesis, multiple low-dose projections are acquired in a single scanning direction over a limited angular range to produce cross-sectional planes through the breast for three-dimensional imaging interpretation. We built a next-generation tomosynthesis system capable of multidirectional source motion with the intent to customize scanning motions around “suspicious findings”. Customized acquisitions can improve the image quality in areas that require increased scrutiny, such as breast cancers, architectural distortions, and dense clusters. In this paper, virtual clinical trial techniques were used to analyze whether a finding or area at high risk of masking cancers can be detected in a single low-dose projection and thus be used for motion planning. This represents a step towards customizing the subsequent low-dose projection acquisitions autonomously, guided by the first low-dose projection; we call this technique “self-steering tomosynthesis.” A U-Net was used to classify the low-dose projections into “risk classes” in simulated breasts with soft-tissue lesions; class probabilities were modified using post hoc Dirichlet calibration (DC). DC improved the multiclass segmentation (Dice = 0.43 vs. 0.28 before DC) and significantly reduced false positives (FPs) from the class of the highest risk of masking (sensitivity = 81.3% at 2 FPs per image vs. 76.0%). This simulation-based study demonstrated the feasibility of identifying suspicious areas using a single low-dose projection for self-steering tomosynthesis. Full article
(This article belongs to the Special Issue Artificial Intelligence in Breast Cancer Screening)
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10 pages, 440 KiB  
Review
Deep Learning Approaches with Digital Mammography for Evaluating Breast Cancer Risk, a Narrative Review
by Maham Siddique, Michael Liu, Phuong Duong, Sachin Jambawalikar and Richard Ha
Tomography 2023, 9(3), 1110-1119; https://doi.org/10.3390/tomography9030091 - 06 Jun 2023
Cited by 3 | Viewed by 2090
Abstract
Breast cancer remains the leading cause of cancer-related deaths in women worldwide. Current screening regimens and clinical breast cancer risk assessment models use risk factors such as demographics and patient history to guide policy and assess risk. Applications of artificial intelligence methods (AI) [...] Read more.
Breast cancer remains the leading cause of cancer-related deaths in women worldwide. Current screening regimens and clinical breast cancer risk assessment models use risk factors such as demographics and patient history to guide policy and assess risk. Applications of artificial intelligence methods (AI) such as deep learning (DL) and convolutional neural networks (CNNs) to evaluate individual patient information and imaging showed promise as personalized risk models. We reviewed the current literature for studies related to deep learning and convolutional neural networks with digital mammography for assessing breast cancer risk. We discussed the literature and examined the ongoing and future applications of deep learning techniques in breast cancer risk modeling. Full article
(This article belongs to the Special Issue Artificial Intelligence in Breast Cancer Screening)
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16 pages, 1087 KiB  
Review
Advances in Focused Ultrasound for the Treatment of Brain Tumors
by Rohan Rao, Anjali Patel, Kunal Hanchate, Eric Robinson, Aniela Edwards, Sanjit Shah, Dominique Higgins, Kevin J. Haworth, Brandon Lucke-Wold, Daniel Pomeranz Krummel and Soma Sengupta
Tomography 2023, 9(3), 1094-1109; https://doi.org/10.3390/tomography9030090 - 29 May 2023
Cited by 1 | Viewed by 2725
Abstract
Employing the full arsenal of therapeutics to treat brain tumors is limited by the relative impermeability of the blood–brain and blood–tumor barriers. In physiologic states, the blood–brain barrier serves a protective role by passively and actively excluding neurotoxic compounds; however, this functionality limits [...] Read more.
Employing the full arsenal of therapeutics to treat brain tumors is limited by the relative impermeability of the blood–brain and blood–tumor barriers. In physiologic states, the blood–brain barrier serves a protective role by passively and actively excluding neurotoxic compounds; however, this functionality limits the penetrance of therapeutics into the tumor microenvironment. Focused ultrasound technology provides a method for overcoming the blood–brain and blood–tumor barriers through ultrasound frequency to transiently permeabilize or disrupt these barriers. Concomitant delivery of therapeutics has allowed for previously impermeable agents to reach the tumor microenvironment. This review details the advances in focused ultrasound in both preclinical models and clinical studies, with a focus on its safety profile. We then turn towards future directions in focused ultrasound-mediated therapies for brain tumors. Full article
(This article belongs to the Special Issue Current Trends in Diagnostic and Therapeutic Imaging of Brain Tumors)
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11 pages, 959 KiB  
Article
Spontaneous Soft Tissue Hematomas in Patients with Coagulation Impairment: Safety and Efficacy of Transarterial Embolization
by Davide Fior, Stefano Di Provvido, Davide Leni, Rocco Corso, Lorenzo Paolo Moramarco, Matteo Pileri, Rosario Francesco Grasso, Domiziana Santucci and Eliodoro Faiella
Tomography 2023, 9(3), 1083-1093; https://doi.org/10.3390/tomography9030089 - 28 May 2023
Viewed by 2156
Abstract
The aim of this study is to report the authors’ experience of percutaneous transarterial embolization (TAE) in patients with spontaneous soft tissue hematomas (SSTH) and active bleeding with anticoagulation impairment. The study retrospectively identified 78 patients who received a diagnosis of SSTH by [...] Read more.
The aim of this study is to report the authors’ experience of percutaneous transarterial embolization (TAE) in patients with spontaneous soft tissue hematomas (SSTH) and active bleeding with anticoagulation impairment. The study retrospectively identified 78 patients who received a diagnosis of SSTH by CT scan and underwent TAE between 2010 and 2019 in a single trauma center. The patients were stratified using Popov classification into categories: 2A, 2B, 2C, and 3. The patient’s 30-day survival after TAE was considered the primary outcome; immediate technical success, the need for additional TAE, and TAE-related complications were considered secondary outcomes. Immediate technical success, complication rate, and risk factors for death were analyzed. Follow-up stopped on day 30 from TAE. 27 patients (35%) fell into category 2A, 8 (10%) into category 2B, 4 (5%) into category 2C, and 39 (50%) into category 3. Immediate technical success was achieved in 77 patients (98.7%). Complications included damage at the arterial puncture site (2 patients, 2.5%) and acute kidney injury (24 patients, 31%). Only 2 patients (2.5%) had been discharged with a new diagnosis of chronic kidney disease. The 30-day overall mortality rate was 19% (15 patients). The mortality rate was higher in hemodynamically unstable patients, in Popov categories 2B, 2C, and 3, and in patients with an initial eGFR < 30 mL/min × 1.73 m2. The study demonstrated a higher mortality risk for categories 2B, 2C, and 3 compared to category 2A. Nonetheless, TAE has proven effective and safe in type 2A patients. Even though it is unclear whether type 2A patients could benefit from conservative treatment rather than TAE, in the authors’ opinion, a TAE endovascular approach should be promptly considered for all patients in ACT with active bleeding demonstrated on CT scans. Full article
(This article belongs to the Section Cardiovascular Imaging)
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12 pages, 795 KiB  
Review
Extended Reality in Diagnostic Imaging—A Literature Review
by Paulina Kukla, Karolina Maciejewska, Iga Strojna, Małgorzata Zapał, Grzegorz Zwierzchowski and Bartosz Bąk
Tomography 2023, 9(3), 1071-1082; https://doi.org/10.3390/tomography9030088 - 24 May 2023
Cited by 5 | Viewed by 2458
Abstract
The utilization of extended reality (ER) has been increasingly explored in the medical field over the past ten years. A comprehensive analysis of scientific publications was conducted to assess the applications of ER in the field of diagnostic imaging, including ultrasound, interventional radiology, [...] Read more.
The utilization of extended reality (ER) has been increasingly explored in the medical field over the past ten years. A comprehensive analysis of scientific publications was conducted to assess the applications of ER in the field of diagnostic imaging, including ultrasound, interventional radiology, and computed tomography. The study also evaluated the use of ER in patient positioning and medical education. Additionally, we explored the potential of ER as a replacement for anesthesia and sedation during examinations. The use of ER technologies in medical education has received increased attention in recent years. This technology allows for a more interactive and engaging educational experience, particularly in anatomy and patient positioning, although the question may be asked: is the technology and maintenance cost worth the investment? The results of the analyzed studies suggest that implementing augmented reality in clinical practice is a positive phenomenon that expands the diagnostic capabilities of imaging studies, education, and positioning. The results suggest that ER has significant potential to improve diagnostic imaging procedures’ accuracy and efficiency and enhance the patient experience through increased visualization and understanding of medical conditions. Despite these promising advancements, further research is needed to fully realize the potential of ER in the medical field and to address the challenges and limitations associated with its integration into clinical practice. Full article
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9 pages, 1097 KiB  
Article
Perfusion-Weighted Imaging: The Use of a Novel Perfusion Scoring Criteria to Improve the Assessment of Brain Tumor Recurrence versus Treatment Effects
by Sneha Sai Mannam, Chibueze D. Nwagwu, Christina Sumner, Brent D. Weinberg and Kimberly B. Hoang
Tomography 2023, 9(3), 1062-1070; https://doi.org/10.3390/tomography9030087 - 23 May 2023
Cited by 1 | Viewed by 1535
Abstract
Introduction: Imaging surveillance of contrast-enhancing lesions after the treatment of malignant brain tumors with radiation is plagued by an inability to reliably distinguish between tumor recurrence and treatment effects. Magnetic resonance perfusion-weighted imaging (PWI)—among other advanced brain tumor imaging modalities—is a useful adjunctive [...] Read more.
Introduction: Imaging surveillance of contrast-enhancing lesions after the treatment of malignant brain tumors with radiation is plagued by an inability to reliably distinguish between tumor recurrence and treatment effects. Magnetic resonance perfusion-weighted imaging (PWI)—among other advanced brain tumor imaging modalities—is a useful adjunctive tool for distinguishing between these two entities but can be clinically unreliable, leading to the need for tissue sampling to confirm diagnosis. This may be partially because clinical PWI interpretation is non-standardized and no grading criteria are used for assessment, leading to interpretation discrepancies. This variance in the interpretation of PWI and its subsequent effect on the predictive value has not been studied. Our objective is to propose structured perfusion scoring criteria and determine their effect on the clinical value of PWI. Methods: Patients treated at a single institution between 2012 and 2022 who had prior irradiated malignant brain tumors and subsequent progression of contrast-enhancing lesions determined by PWI were retrospectively studied from CTORE (CNS Tumor Outcomes Registry at Emory). PWI was given two separate qualitative scores (high, intermediate, or low perfusion). The first (control) was assigned by a neuroradiologist in the radiology report in the course of interpretation with no additional instruction. The second (experimental) was assigned by a neuroradiologist with additional experience in brain tumor interpretation using a novel perfusion scoring rubric. The perfusion assessments were divided into three categories, each directly corresponding to the pathology-reported classification of residual tumor content. The interpretation accuracy in predicting the true tumor percentage, our primary outcome, was assessed through Chi-squared analysis, and inter-rater reliability was assessed using Cohen’s Kappa. Results: Our 55-patient cohort had a mean age of 53.5 ± 12.2 years. The percentage agreement between the two scores was 57.4% (κ: 0.271). Upon conducting the Chi-squared analysis, we found an association with the experimental group reads (p-value: 0.014) but no association with the control group reads (p-value: 0.734) in predicting tumor recurrence versus treatment effects. Conclusions: With our study, we showed that having an objective perfusion scoring rubric aids in improved PWI interpretation. Although PWI is a powerful tool for CNS lesion diagnosis, methodological radiology evaluation greatly improves the accurate assessment and characterization of tumor recurrence versus treatment effects by all neuroradiologists. Further work should focus on standardizing and validating scoring rubrics for PWI evaluation in tumor patients to improve diagnostic accuracy. Full article
(This article belongs to the Special Issue Current Trends in Diagnostic and Therapeutic Imaging of Brain Tumors)
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10 pages, 2856 KiB  
Article
Applying a Radiation Therapy Volume Analysis Pipeline to Determine the Utility of Spectroscopic MRI-Guided Adaptive Radiation Therapy for Glioblastoma
by Anuradha G. Trivedi, Su Hyun Kim, Karthik K. Ramesh, Alexander S. Giuffrida, Brent D. Weinberg, Eric A. Mellon, Lawrence R. Kleinberg, Peter B. Barker, Hui Han, Hui-Kuo G. Shu, Hyunsuk Shim and Eduard Schreibmann
Tomography 2023, 9(3), 1052-1061; https://doi.org/10.3390/tomography9030086 - 21 May 2023
Viewed by 1837
Abstract
Accurate radiation therapy (RT) targeting is crucial for glioblastoma treatment but may be challenging using clinical imaging alone due to the infiltrative nature of glioblastomas. Precise targeting by whole-brain spectroscopic MRI, which maps tumor metabolites including choline (Cho) and N-acetylaspartate (NAA), can quantify [...] Read more.
Accurate radiation therapy (RT) targeting is crucial for glioblastoma treatment but may be challenging using clinical imaging alone due to the infiltrative nature of glioblastomas. Precise targeting by whole-brain spectroscopic MRI, which maps tumor metabolites including choline (Cho) and N-acetylaspartate (NAA), can quantify early treatment-induced molecular changes that other traditional modalities cannot measure. We developed a pipeline to determine how spectroscopic MRI changes during early RT are associated with patient outcomes to provide insight into the utility of adaptive RT planning. Data were obtained from a study (NCT03137888) where glioblastoma patients received high-dose RT guided by the pre-RT Cho/NAA twice normal (Cho/NAA ≥ 2x) volume, and received spectroscopic MRI scans pre- and mid-RT. Overlap statistics between pre- and mid-RT scans were used to quantify metabolic activity changes after two weeks of RT. Log-rank tests were used to quantify the relationship between imaging metrics and patient overall and progression-free survival (OS/PFS). Patients with lower Jaccard/Dice coefficients had longer PFS (p = 0.045 for both), and patients with lower Jaccard/Dice coefficients had higher OS trending towards significance (p = 0.060 for both). Cho/NAA ≥ 2x volumes changed significantly during early RT, putting healthy tissue at risk of irradiation, and warranting further study into using adaptive RT planning. Full article
(This article belongs to the Special Issue Current Trends in Diagnostic and Therapeutic Imaging of Brain Tumors)
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11 pages, 1588 KiB  
Article
Comparison of CT and Dixon MR Abdominal Adipose Tissue Quantification Using a Unified Computer-Assisted Software Framework
by Li-Yueh Hsu, Zara Ali, Hadi Bagheri, Fahimul Huda, Bernadette A. Redd and Elizabeth C. Jones
Tomography 2023, 9(3), 1041-1051; https://doi.org/10.3390/tomography9030085 - 20 May 2023
Cited by 1 | Viewed by 1700
Abstract
Purpose: Reliable and objective measures of abdominal fat distribution across imaging modalities are essential for various clinical and research scenarios, such as assessing cardiometabolic disease risk due to obesity. We aimed to compare quantitative measures of subcutaneous (SAT) and visceral (VAT) adipose tissues [...] Read more.
Purpose: Reliable and objective measures of abdominal fat distribution across imaging modalities are essential for various clinical and research scenarios, such as assessing cardiometabolic disease risk due to obesity. We aimed to compare quantitative measures of subcutaneous (SAT) and visceral (VAT) adipose tissues in the abdomen between computed tomography (CT) and Dixon-based magnetic resonance (MR) images using a unified computer-assisted software framework. Materials and Methods: This study included 21 subjects who underwent abdominal CT and Dixon MR imaging on the same day. For each subject, two matched axial CT and fat-only MR images at the L2-L3 and the L4-L5 intervertebral levels were selected for fat quantification. For each image, an outer and an inner abdominal wall regions as well as SAT and VAT pixel masks were automatically generated by our software. The computer-generated results were then inspected and corrected by an expert reader. Results: There were excellent agreements for both abdominal wall segmentation and adipose tissue quantification between matched CT and MR images. Pearson coefficients were 0.97 for both outer and inner region segmentation, 0.99 for SAT, and 0.97 for VAT quantification. Bland–Altman analyses indicated minimum biases in all comparisons. Conclusion: We showed that abdominal adipose tissue can be reliably quantified from both CT and Dixon MR images using a unified computer-assisted software framework. This flexible framework has a simple-to-use workflow to measure SAT and VAT from both modalities to support various clinical research applications. Full article
(This article belongs to the Section Abdominal Imaging)
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12 pages, 7930 KiB  
Article
Quantitative Assessment of Intervertebral Disc Composition by MRI: Sensitivity to Diurnal Variation
by Hiroyuki Hamaguchi, Maho Kitagawa, Daiki Sakamoto, Ulrich Katscher, Hideki Sudo, Katsuhisa Yamada, Kohsuke Kudo and Khin Khin Tha
Tomography 2023, 9(3), 1029-1040; https://doi.org/10.3390/tomography9030084 - 16 May 2023
Cited by 3 | Viewed by 1628
Abstract
Whether diurnal variation exists in quantitative MRI indices such as the T1rho relaxation time (T1ρ) of the intervertebral disc (IVD) is yet to be explored. This prospective study aimed to evaluate the diurnal variation in T1ρ, apparent diffusion coefficient (ADC), and electrical conductivity [...] Read more.
Whether diurnal variation exists in quantitative MRI indices such as the T1rho relaxation time (T1ρ) of the intervertebral disc (IVD) is yet to be explored. This prospective study aimed to evaluate the diurnal variation in T1ρ, apparent diffusion coefficient (ADC), and electrical conductivity (σ) of lumbar IVD and its relationship with other MRI or clinical indices. Lumbar spine MRI, including T1ρ imaging, diffusion-weighted imaging (DWI), and electric properties tomography (EPT), was conducted on 17 sedentary workers twice (morning and evening) on the same day. The T1ρ, ADC, and σ of IVD were compared between the time points. Their diurnal variation, if any, was tested for correlation with age, body mass index (BMI), IVD level, Pfirrmann grade, scan interval, and diurnal variation in IVD height index. The results showed a significant decrease in T1ρ and ADC and a significant increase in the σ of IVD in the evening. T1ρ variation had a weak correlation with age and scan interval, and ADC variation with scan interval. Diurnal variation exists for the T1ρ, ADC, and σ of lumbar IVD, which should be accounted for in image interpretation. This variation is thought to be due to diurnal variations in intradiscal water, proteoglycan, and sodium ion concentration. Full article
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10 pages, 565 KiB  
Article
Coronary Computed Tomography Angiography with Deep Learning Image Reconstruction: A Preliminary Study to Evaluate Radiation Exposure Reduction
by Rossana Bona, Piergiorgio Marini, Davide Turilli, Salvatore Masala and Mariano Scaglione
Tomography 2023, 9(3), 1019-1028; https://doi.org/10.3390/tomography9030083 - 16 May 2023
Viewed by 1409
Abstract
Coronary computed tomography angiography (CCTA) is a medical imaging technique that produces detailed images of the coronary arteries. Our work focuses on the optimization of the prospectively ECG-triggered scan technique, which delivers the radiation efficiently only during a fraction of the R–R interval, [...] Read more.
Coronary computed tomography angiography (CCTA) is a medical imaging technique that produces detailed images of the coronary arteries. Our work focuses on the optimization of the prospectively ECG-triggered scan technique, which delivers the radiation efficiently only during a fraction of the R–R interval, matching the aim of reducing radiation dose in this increasingly used radiological examination. In this work, we analyzed how the median DLP (Dose-Length Product) values for CCTA of our Center decreased significantly in recent times mainly due to a notable change in the technology used. We passed from a median DLP value of 1158 mGy·cm to 221 mGy·cm for the whole exam and from a value of 1140 mGy·cm to 204 mGy·cm if considering CCTA scanning only. The result was obtained through the association of important factors during the dose imaging optimization: technological improvement, acquisition technique, and image reconstruction algorithm intervention. The combination of these three factors allows us to perform a faster and more accurate prospective CCTA with a lower radiation dose. Our future aim is to tune the image quality through a detectability-based study, combining algorithm strength with automatic dose settings. Full article
(This article belongs to the Special Issue Radiation Protection Opportunities in Medical Imaging)
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9 pages, 1201 KiB  
Article
Frequency and Pattern of MRI Diffusion Restrictions after Diagnostic Catheter Neuroangiography
by Elisabeth Kesseler, Svenja Tafelmeier, Omid Nikoubashman, Anca-Maria Iancu, João Pinho and Martin Wiesmann
Tomography 2023, 9(3), 1010-1018; https://doi.org/10.3390/tomography9030082 - 12 May 2023
Cited by 1 | Viewed by 1286
Abstract
(1) Background: We investigated the frequency, location, and lesion size of diffusion restrictions (DR) in magnetic resonance imaging (MRI) of asymptomatic patients after diagnostic angiography and assessed risk factors for their occurrence. (2) Methods: We analyzed diffusion-weighted images (DWI) of 344 patients undergoing [...] Read more.
(1) Background: We investigated the frequency, location, and lesion size of diffusion restrictions (DR) in magnetic resonance imaging (MRI) of asymptomatic patients after diagnostic angiography and assessed risk factors for their occurrence. (2) Methods: We analyzed diffusion-weighted images (DWI) of 344 patients undergoing diagnostic angiographies in a neuroradiologic center. Only asymptomatic patients who received a magnetic resonance imaging (MRI) examination within seven days after the angiography were included. (3) Results: Asymptomatic infarcts on DWI were identified in 17% of the cases after diagnostic angiography. In these 59 patients, a total of 167 lesions were noted. The diameter of the lesions was 1–5 mm in 128 lesions, and 5–10 mm in 39 cases. Dot-shaped diffusion restrictions were found most frequently (n = 163, 97.6%). None of the patients had neurological deficits during or after angiography. Significant correlations were found between the occurrence of lesions and patient age (p < 0.001), history of atherosclerosis (p = 0.014), cerebral infarction (p = 0.026), or coronary heart disease/heart attack (p = 0.027); and the amount of contrast medium used (p = 0.047) and fluoroscopy time (p = 0.033). (4) Conclusions: With an incidence of 17%, we observed a comparatively high risk for asymptomatic cerebral ischemia after diagnostic neuroangiography. Further measures to reduce the risk of silent embolic infarcts and improve the safety of neuroangiography are warranted. Full article
(This article belongs to the Section Neuroimaging)
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15 pages, 1430 KiB  
Article
Co-Clinical Imaging Metadata Information (CIMI) for Cancer Research to Promote Open Science, Standardization, and Reproducibility in Preclinical Imaging
by Stephen M. Moore, James D. Quirk, Andrew W. Lassiter, Richard Laforest, Gregory D. Ayers, Cristian T. Badea, Andriy Y. Fedorov, Paul E. Kinahan, Matthew Holbrook, Peder E. Z. Larson, Renuka Sriram, Thomas L. Chenevert, Dariya Malyarenko, John Kurhanewicz, A. McGarry Houghton, Brian D. Ross, Stephen Pickup, James C. Gee, Rong Zhou, Seth T. Gammon, Henry Charles Manning, Raheleh Roudi, Heike E. Daldrup-Link, Michael T. Lewis, Daniel L. Rubin, Thomas E. Yankeelov and Kooresh I. Shoghiadd Show full author list remove Hide full author list
Tomography 2023, 9(3), 995-1009; https://doi.org/10.3390/tomography9030081 - 11 May 2023
Cited by 1 | Viewed by 2815
Abstract
Preclinical imaging is a critical component in translational research with significant complexities in workflow and site differences in deployment. Importantly, the National Cancer Institute’s (NCI) precision medicine initiative emphasizes the use of translational co-clinical oncology models to address the biological and molecular bases [...] Read more.
Preclinical imaging is a critical component in translational research with significant complexities in workflow and site differences in deployment. Importantly, the National Cancer Institute’s (NCI) precision medicine initiative emphasizes the use of translational co-clinical oncology models to address the biological and molecular bases of cancer prevention and treatment. The use of oncology models, such as patient-derived tumor xenografts (PDX) and genetically engineered mouse models (GEMMs), has ushered in an era of co-clinical trials by which preclinical studies can inform clinical trials and protocols, thus bridging the translational divide in cancer research. Similarly, preclinical imaging fills a translational gap as an enabling technology for translational imaging research. Unlike clinical imaging, where equipment manufacturers strive to meet standards in practice at clinical sites, standards are neither fully developed nor implemented in preclinical imaging. This fundamentally limits the collection and reporting of metadata to qualify preclinical imaging studies, thereby hindering open science and impacting the reproducibility of co-clinical imaging research. To begin to address these issues, the NCI co-clinical imaging research program (CIRP) conducted a survey to identify metadata requirements for reproducible quantitative co-clinical imaging. The enclosed consensus-based report summarizes co-clinical imaging metadata information (CIMI) to support quantitative co-clinical imaging research with broad implications for capturing co-clinical data, enabling interoperability and data sharing, as well as potentially leading to updates to the preclinical Digital Imaging and Communications in Medicine (DICOM) standard. Full article
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14 pages, 1517 KiB  
Article
Extension of Lung Damage at Chest Computed Tomography in Severely Ill COVID-19 Patients Treated with Interleukin-6 Receptor Blockers Correlates with Inflammatory Cytokines Production and Prognosis
by Lucio Calandriello, Enrico De Lorenzis, Giuseppe Cicchetti, Rosa D’Abronzo, Amato Infante, Federico Castaldo, Annemilia Del Ciello, Alessandra Farchione, Elisa Gremese, Riccardo Marano, Luigi Natale, Maria Antonietta D’Agostino, Silvia Laura Bosello and Anna Rita Larici
Tomography 2023, 9(3), 981-994; https://doi.org/10.3390/tomography9030080 - 11 May 2023
Viewed by 1737
Abstract
Elevated inflammatory markers are associated with severe coronavirus disease 2019 (COVID-19), and some patients benefit from Interleukin (IL)-6 pathway inhibitors. Different chest computed tomography (CT) scoring systems have shown a prognostic value in COVID-19, but not specifically in anti-IL-6-treated patients at high risk [...] Read more.
Elevated inflammatory markers are associated with severe coronavirus disease 2019 (COVID-19), and some patients benefit from Interleukin (IL)-6 pathway inhibitors. Different chest computed tomography (CT) scoring systems have shown a prognostic value in COVID-19, but not specifically in anti-IL-6-treated patients at high risk of respiratory failure. We aimed to explore the relationship between baseline CT findings and inflammatory conditions and to evaluate the prognostic value of chest CT scores and laboratory findings in COVID-19 patients specifically treated with anti-IL-6. Baseline CT lung involvement was assessed in 51 hospitalized COVID-19 patients naive to glucocorticoids and other immunosuppressants using four CT scoring systems. CT data were correlated with systemic inflammation and 30-day prognosis after anti-IL-6 treatment. All the considered CT scores showed a negative correlation with pulmonary function and a positive one with C-reactive protein (CRP), IL-6, IL-8, and Tumor Necrosis Factor α (TNF-α) serum levels. All the performed scores were prognostic factors, but the disease extension assessed by the six-lung-zone CT score (S24) was the only independently associated with intensive care unit (ICU) admission (p = 0.04). In conclusion, CT involvement correlates with laboratory inflammation markers and is an independent prognostic factor in COVID-19 patients representing a further tool to implement prognostic stratification in hospitalized patients. Full article
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14 pages, 2268 KiB  
Article
Automated Placement of Scan and Pre-Scan Volumes for Breast MRI Using a Convolutional Neural Network
by Timothy J. Allen, Leah C. Henze Bancroft, Kang Wang, Ping Ni Wang, Orhan Unal, Lloyd D. Estkowski, Ty A. Cashen, Ersin Bayram, Roberta M. Strigel and James H. Holmes
Tomography 2023, 9(3), 967-980; https://doi.org/10.3390/tomography9030079 - 10 May 2023
Cited by 1 | Viewed by 1465
Abstract
Graphically prescribed patient-specific imaging volumes and local pre-scan volumes are routinely placed by MRI technologists to optimize image quality. However, manual placement of these volumes by MR technologists is time-consuming, tedious, and subject to intra- and inter-operator variability. Resolving these bottlenecks is critical [...] Read more.
Graphically prescribed patient-specific imaging volumes and local pre-scan volumes are routinely placed by MRI technologists to optimize image quality. However, manual placement of these volumes by MR technologists is time-consuming, tedious, and subject to intra- and inter-operator variability. Resolving these bottlenecks is critical with the rise in abbreviated breast MRI exams for screening purposes. This work proposes an automated approach for the placement of scan and pre-scan volumes for breast MRI. Anatomic 3-plane scout image series and associated scan volumes were retrospectively collected from 333 clinical breast exams acquired on 10 individual MRI scanners. Bilateral pre-scan volumes were also generated and reviewed in consensus by three MR physicists. A deep convolutional neural network was trained to predict both the scan and pre-scan volumes from the 3-plane scout images. The agreement between the network-predicted volumes and the clinical scan volumes or physicist-placed pre-scan volumes was evaluated using the intersection over union, the absolute distance between volume centers, and the difference in volume sizes. The scan volume model achieved a median 3D intersection over union of 0.69. The median error in scan volume location was 2.7 cm and the median size error was 2%. The median 3D intersection over union for the pre-scan placement was 0.68 with no significant difference in mean value between the left and right pre-scan volumes. The median error in the pre-scan volume location was 1.3 cm and the median size error was −2%. The average estimated uncertainty in positioning or volume size for both models ranged from 0.2 to 3.4 cm. Overall, this work demonstrates the feasibility of an automated approach for the placement of scan and pre-scan volumes based on a neural network model. Full article
(This article belongs to the Special Issue New Advances in Breast Imaging)
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12 pages, 855 KiB  
Communication
Radiation Dose Management in Computed Tomography: Introduction to the Practice at a Single Facility
by Yusuke Inoue
Tomography 2023, 9(3), 955-966; https://doi.org/10.3390/tomography9030078 - 06 May 2023
Cited by 3 | Viewed by 1764
Abstract
Although the clinical benefits of computed tomography (CT) are undoubtedly high, radiation doses received by patients are also relatively high; therefore, radiation dose management is mandatory to optimize CT radiation doses and prevent excessive radiation events. This article describes CT dose management practice [...] Read more.
Although the clinical benefits of computed tomography (CT) are undoubtedly high, radiation doses received by patients are also relatively high; therefore, radiation dose management is mandatory to optimize CT radiation doses and prevent excessive radiation events. This article describes CT dose management practice at a single facility. Many imaging protocols are used in CT depending on the clinical indications, scan region, and CT scanner; thus, managing the protocols is the first step for optimization. The appropriateness of the radiation dose for each protocol and scanner is verified, while answering whether the dose is the minimum to obtain diagnostic-quality images. Moreover, examinations with exceptionally high doses are identified, and the cause and clinical validity of the high dose are assessed. Daily imaging practice should follow standardized procedures, avoiding operator-dependent errors, and information required for radiation dose management should be recorded at each examination. The imaging protocols and procedures are reviewed for continuous improvement based on regular dose analysis and multidisciplinary team collaboration. The participation of many staff members in the dose management process is expected to contribute to promoting radiation safety through increased staff awareness. Full article
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13 pages, 2213 KiB  
Article
Mutant Isocitrate Dehydrogenase 1 Expression Enhances Response of Gliomas to the Histone Deacetylase Inhibitor Belinostat
by Chi-Ming Chang, Karthik K. Ramesh, Vicki Huang, Saumya Gurbani, Lawrence R. Kleinberg, Brent D. Weinberg, Hyunsuk Shim and Hui-Kuo G. Shu
Tomography 2023, 9(3), 942-954; https://doi.org/10.3390/tomography9030077 - 04 May 2023
Viewed by 1618
Abstract
Histone deacetylase inhibitors (HDACis) are drugs that target the epigenetic state of cells by modifying the compaction of chromatin through effects on histone acetylation. Gliomas often harbor a mutation of isocitrate dehydrogenase (IDH) 1 or 2 that leads to changes in their epigenetic [...] Read more.
Histone deacetylase inhibitors (HDACis) are drugs that target the epigenetic state of cells by modifying the compaction of chromatin through effects on histone acetylation. Gliomas often harbor a mutation of isocitrate dehydrogenase (IDH) 1 or 2 that leads to changes in their epigenetic state presenting a hypermethylator phenotype. We postulated that glioma cells with IDH mutation, due to the presence of epigenetic changes, will show increased sensitivity to HDACis. This hypothesis was tested by expressing mutant IDH1 with a point alteration—converting arginine 132 to histidine—within glioma cell lines that contain wild-type IDH1. Glioma cells engineered to express mutant IDH1 produced D-2-hydroxyglutarate as expected. When assessed for response to the pan-HDACi drug belinostat, mutant IDH1-expressing glioma cells were subjected to more potent inhibition of growth than the corresponding control cells. Increased sensitivity to belinostat correlated with the increased induction of apoptosis. Finally, a phase I trial assessing the addition of belinostat to standard-of-care therapy for newly diagnosed glioblastoma patients included one patient with a mutant IDH1 tumor. This mutant IDH1 tumor appeared to display greater sensitivity to the addition of belinostat than the other cases with wild-type IDH tumors based on both standard magnetic resonance imaging (MRI) and advanced spectroscopic MRI criteria. These data together suggest that IDH mutation status within gliomas may serve as a biomarker of response to HDACis. Full article
(This article belongs to the Special Issue Current Trends in Diagnostic and Therapeutic Imaging of Brain Tumors)
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11 pages, 735 KiB  
Review
The National Cancer Institute’s Co-Clinical Quantitative Imaging Research Resources for Precision Medicine in Preclinical and Clinical Settings
by Huiming Zhang
Tomography 2023, 9(3), 931-941; https://doi.org/10.3390/tomography9030076 - 30 Apr 2023
Viewed by 1640
Abstract
Genetically engineered mouse models (GEMMs) and patient-derived xenograft mouse models (PDXs) can recapitulate important biological features of cancer. They are often part of precision medicine studies in a co-clinical setting, in which therapeutic investigations are conducted in patients and in parallel (or sequentially) [...] Read more.
Genetically engineered mouse models (GEMMs) and patient-derived xenograft mouse models (PDXs) can recapitulate important biological features of cancer. They are often part of precision medicine studies in a co-clinical setting, in which therapeutic investigations are conducted in patients and in parallel (or sequentially) in cohorts of GEMMs or PDXs. Employing radiology-based quantitative imaging in these studies allows in vivo assessment of disease response in real time, providing an important opportunity to bridge precision medicine from the bench to the bedside. The Co-Clinical Imaging Research Resource Program (CIRP) of the National Cancer Institute focuses on the optimization of quantitative imaging methods to improve co-clinical trials. The CIRP supports 10 different co-clinical trial projects, spanning diverse tumor types, therapeutic interventions, and imaging modalities. Each CIRP project is tasked to deliver a unique web resource to support the cancer community with the necessary methods and tools to conduct co-clinical quantitative imaging studies. This review provides an update of the CIRP web resources, network consensus, technology advances, and a perspective on the future of the CIRP. The presentations in this special issue of Tomography were contributed by the CIRP working groups, teams, and associate members. Full article
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22 pages, 7136 KiB  
Review
Computed Tomography Urography: State of the Art and Beyond
by Michaela Cellina, Maurizio Cè, Nicolo’ Rossini, Laura Maria Cacioppa, Velio Ascenti, Gianpaolo Carrafiello and Chiara Floridi
Tomography 2023, 9(3), 909-930; https://doi.org/10.3390/tomography9030075 - 30 Apr 2023
Cited by 6 | Viewed by 3665
Abstract
Computed Tomography Urography (CTU) is a multiphase CT examination optimized for imaging kidneys, ureters, and bladder, complemented by post-contrast excretory phase imaging. Different protocols are available for contrast administration and image acquisition and timing, with different strengths and limits, mainly related to kidney [...] Read more.
Computed Tomography Urography (CTU) is a multiphase CT examination optimized for imaging kidneys, ureters, and bladder, complemented by post-contrast excretory phase imaging. Different protocols are available for contrast administration and image acquisition and timing, with different strengths and limits, mainly related to kidney enhancement, ureters distension and opacification, and radiation exposure. The availability of new reconstruction algorithms, such as iterative and deep-learning-based reconstruction has dramatically improved the image quality and reducing radiation exposure at the same time. Dual-Energy Computed Tomography also has an important role in this type of examination, with the possibility of renal stone characterization, the availability of synthetic unenhanced phases to reduce radiation dose, and the availability of iodine maps for a better interpretation of renal masses. We also describe the new artificial intelligence applications for CTU, focusing on radiomics to predict tumor grading and patients’ outcome for a personalized therapeutic approach. In this narrative review, we provide a comprehensive overview of CTU from the traditional to the newest acquisition techniques and reconstruction algorithms, and the possibility of advanced imaging interpretation to provide an up-to-date guide for radiologists who want to better comprehend this technique. Full article
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8 pages, 750 KiB  
Article
Can Machine Learning Be Better than Biased Readers?
by Atsuhiro Hibi, Rui Zhu and Pascal N. Tyrrell
Tomography 2023, 9(3), 901-908; https://doi.org/10.3390/tomography9030074 - 28 Apr 2023
Viewed by 1239
Abstract
Background: Training machine learning (ML) models in medical imaging requires large amounts of labeled data. To minimize labeling workload, it is common to divide training data among multiple readers for separate annotation without consensus and then combine the labeled data for training a [...] Read more.
Background: Training machine learning (ML) models in medical imaging requires large amounts of labeled data. To minimize labeling workload, it is common to divide training data among multiple readers for separate annotation without consensus and then combine the labeled data for training a ML model. This can lead to a biased training dataset and poor ML algorithm prediction performance. The purpose of this study is to determine if ML algorithms can overcome biases caused by multiple readers’ labeling without consensus. Methods: This study used a publicly available chest X-ray dataset of pediatric pneumonia. As an analogy to a practical dataset without labeling consensus among multiple readers, random and systematic errors were artificially added to the dataset to generate biased data for a binary-class classification task. The Resnet18-based convolutional neural network (CNN) was used as a baseline model. A Resnet18 model with a regularization term added as a loss function was utilized to examine for improvement in the baseline model. Results: The effects of false positive labels, false negative labels, and random errors (5–25%) resulted in a loss of AUC (0–14%) when training a binary CNN classifier. The model with a regularized loss function improved the AUC (75–84%) over that of the baseline model (65–79%). Conclusion: This study indicated that it is possible for ML algorithms to overcome individual readers’ biases when consensus is not available. It is recommended to use regularized loss functions when allocating annotation tasks to multiple readers as they are easy to implement and effective in mitigating biased labels. Full article
(This article belongs to the Section Artificial Intelligence in Medical Imaging)
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7 pages, 11892 KiB  
Case Report
COVID-19 Pneumonia with Migratory Pattern in Agammaglobulinemic Patients: A Report of Two Cases and Review of Literature
by Melania Degli Antoni, Verena Crosato, Francesca Pennati, Andrea Borghesi, Graziella Cristini, Roberto Allegri, Susanna Capone, Alberto Bergamasco, Annarosa Soresina, Raffaele Badolato, Roberto Maroldi, Eugenia Quiros-Roldan, Alberto Matteelli, Francesco Castelli and Emanuele Focà
Tomography 2023, 9(3), 894-900; https://doi.org/10.3390/tomography9030073 - 23 Apr 2023
Viewed by 1393
Abstract
X-linked agammaglobulinemia (XLA) is a primary immunodeficiency characterized by marked reduction in serum immunoglobulins and early-onset infections. Coronavirus Disease-2019 (COVID-19) pneumonia in immunocompromised patients presents clinical and radiological peculiarities which have not yet been completely understood. Very few cases of agammaglobulinemic patients with [...] Read more.
X-linked agammaglobulinemia (XLA) is a primary immunodeficiency characterized by marked reduction in serum immunoglobulins and early-onset infections. Coronavirus Disease-2019 (COVID-19) pneumonia in immunocompromised patients presents clinical and radiological peculiarities which have not yet been completely understood. Very few cases of agammaglobulinemic patients with COVID-19 have been reported since the beginning of the pandemic in February 2020. We report two cases of migrant COVID-19 pneumonia in XLA patients. Full article
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