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Volume 10, August
 
 

J. Imaging, Volume 10, Issue 9 (September 2024) – 5 articles

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29 pages, 4861 KiB  
Article
A New Approach for Effective Retrieval of Medical Images: A Step towards Computer-Assisted Diagnosis
by Suchita Sharma and Ashutosh Aggarwal
J. Imaging 2024, 10(9), 210; https://doi.org/10.3390/jimaging10090210 - 26 Aug 2024
Viewed by 271
Abstract
The biomedical imaging field has grown enormously in the past decade. In the era of digitization, the demand for computer-assisted diagnosis is increasing day by day. The COVID-19 pandemic further emphasized how retrieving meaningful information from medical repositories can aid in improving the [...] Read more.
The biomedical imaging field has grown enormously in the past decade. In the era of digitization, the demand for computer-assisted diagnosis is increasing day by day. The COVID-19 pandemic further emphasized how retrieving meaningful information from medical repositories can aid in improving the quality of patient’s diagnosis. Therefore, content-based retrieval of medical images has a very prominent role in fulfilling our ultimate goal of developing automated computer-assisted diagnosis systems. Therefore, this paper presents a content-based medical image retrieval system that extracts multi-resolution, noise-resistant, rotation-invariant texture features in the form of a novel pattern descriptor, i.e., MsNrRiTxP, from medical images. In the proposed approach, the input medical image is initially decomposed into three neutrosophic images on its transformation into the neutrosophic domain. Afterwards, three distinct pattern descriptors, i.e., MsTrP, NrTxP, and RiTxP, are derived at multiple scales from the three neutrosophic images. The proposed MsNrRiTxP pattern descriptor is obtained by scale-wise concatenation of the joint histograms of MsTrP×RiTxP and NrTxP×RiTxP. To demonstrate the efficacy of the proposed system, medical images of different modalities, i.e., CT and MRI, from four test datasets are considered in our experimental setup. The retrieval performance of the proposed approach is exhaustively compared with several existing, recent, and state-of-the-art local binary pattern-based variants. The retrieval rates obtained by the proposed approach for the noise-free and noisy variants of the test datasets are observed to be substantially higher than the compared ones. Full article
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11 pages, 1590 KiB  
Technical Note
Ex Vivo Simultaneous H215O Positron Emission Tomography and Magnetic Resonance Imaging of Porcine Kidneys—A Feasibility Study
by Maibritt Meldgaard Arildsen, Christian Østergaard Mariager, Christoffer Vase Overgaard, Thomas Vorre, Martin Bøjesen, Niels Moeslund, Aage Kristian Olsen Alstrup, Lars Poulsen Tolbod, Mikkel Holm Vendelbo, Steffen Ringgaard, Michael Pedersen and Niels Henrik Buus
J. Imaging 2024, 10(9), 209; https://doi.org/10.3390/jimaging10090209 - 25 Aug 2024
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Abstract
The aim was to establish combined H215O PET/MRI during ex vivo normothermic machine perfusion (NMP) of isolated porcine kidneys. We examined whether changes in renal arterial blood flow (RABF) are accompanied by changes of a similar magnitude in renal blood [...] Read more.
The aim was to establish combined H215O PET/MRI during ex vivo normothermic machine perfusion (NMP) of isolated porcine kidneys. We examined whether changes in renal arterial blood flow (RABF) are accompanied by changes of a similar magnitude in renal blood perfusion (RBP) as well as the relation between RBP and renal parenchymal oxygenation (RPO). Methods: Pig kidneys (n = 7) were connected to a NMP circuit. PET/MRI was performed at two different pump flow levels: a blood-oxygenation-level-dependent (BOLD) MRI sequence performed simultaneously with a H215O PET sequence for determination of RBP. Results: RBP was measured using H215O PET in all kidneys (flow 1: 0.42–0.76 mL/min/g, flow 2: 0.7–1.6 mL/min/g). We found a linear correlation between changes in delivered blood flow from the perfusion pump and changes in the measured RBP using PET imaging (r2 = 0.87). Conclusion: Our study demonstrated the feasibility of combined H215O PET/MRI during NMP of isolated porcine kidneys with tissue oxygenation being stable over time. The introduction of H215O PET/MRI in nephrological research could be highly relevant for future pre-transplant kidney evaluation and as a tool for studying renal physiology in healthy and diseased kidneys. Full article
(This article belongs to the Section Medical Imaging)
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20 pages, 20653 KiB  
Article
Task-Adaptive Angle Selection for Computed Tomography-Based Defect Detection
by Tianyuan Wang, Virginia Florian, Richard Schielein, Christian Kretzer, Stefan Kasperl, Felix Lucka and Tristan van Leeuwen
J. Imaging 2024, 10(9), 208; https://doi.org/10.3390/jimaging10090208 - 23 Aug 2024
Viewed by 337
Abstract
Sparse-angle X-ray Computed Tomography (CT) plays a vital role in industrial quality control but leads to an inherent trade-off between scan time and reconstruction quality. Adaptive angle selection strategies try to improve upon this based on the idea that the geometry of the [...] Read more.
Sparse-angle X-ray Computed Tomography (CT) plays a vital role in industrial quality control but leads to an inherent trade-off between scan time and reconstruction quality. Adaptive angle selection strategies try to improve upon this based on the idea that the geometry of the object under investigation leads to an uneven distribution of the information content over the projection angles. Deep Reinforcement Learning (DRL) has emerged as an effective approach for adaptive angle selection in X-ray CT. While previous studies focused on optimizing generic image quality measures using a fixed number of angles, our work extends them by considering a specific downstream task, namely image-based defect detection, and introducing flexibility in the number of angles used. By leveraging prior knowledge about typical defect characteristics, our task-adaptive angle selection method, adaptable in terms of angle count, enables easy detection of defects in the reconstructed images. Full article
(This article belongs to the Section AI in Imaging)
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34 pages, 8070 KiB  
Article
Beyond Nyquist: A Comparative Analysis of 3D Deep Learning Models Enhancing MRI Resolution
by Soumick Chatterjee, Alessandro Sciarra, Max Dünnwald, Anitha Bhat Talagini Ashoka, Mayura Gurjar Cheepinahalli Vasudeva, Shudarsan Saravanan, Venkatesh Thirugnana Sambandham, Pavan Tummala, Steffen Oeltze-Jafra, Oliver Speck and Andreas Nürnberger
J. Imaging 2024, 10(9), 207; https://doi.org/10.3390/jimaging10090207 - 23 Aug 2024
Viewed by 498
Abstract
High-spatial resolution MRI produces abundant structural information, enabling highly accurate clinical diagnosis and image-guided therapeutics. However, the acquisition of high-spatial resolution MRI data typically can come at the expense of less spatial coverage, lower signal-to-noise ratio (SNR), and longer scan time due to [...] Read more.
High-spatial resolution MRI produces abundant structural information, enabling highly accurate clinical diagnosis and image-guided therapeutics. However, the acquisition of high-spatial resolution MRI data typically can come at the expense of less spatial coverage, lower signal-to-noise ratio (SNR), and longer scan time due to physical, physiological and hardware limitations. In order to overcome these limitations, super-resolution MRI deep-learning-based techniques can be utilised. In this work, different state-of-the-art 3D convolution neural network models for super resolution (RRDB, SPSR, UNet, UNet-MSS and ShuffleUNet) were compared for the super-resolution task with the goal of finding the best model in terms of performance and robustness. The public IXI dataset (only structural images) was used. Data were artificially downsampled to obtain lower-resolution spatial MRIs (downsampling factor varying from 8 to 64). When assessing performance using the SSIM metric in the test set, all models performed well. In particular, regardless of the downsampling factor, the UNet consistently obtained the top results. On the other hand, the SPSR model consistently performed worse. In conclusion, UNet and UNet-MSS achieved overall top performances while RRDB performed relatively poorly compared to the other models. Full article
(This article belongs to the Section AI in Imaging)
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13 pages, 4947 KiB  
Article
A Novel Multi-Dimensional Joint Search Method for the Compression of Medical Image Segmentation Models
by Yunhui Zheng, Zhiyong Wu, Fengna Ji, Lei Du and Zhenyu Yang
J. Imaging 2024, 10(9), 206; https://doi.org/10.3390/jimaging10090206 - 23 Aug 2024
Viewed by 353
Abstract
Due to the excellent results achieved by transformers in computer vision, more and more scholars have introduced transformers into the field of medical image segmentation. However, the use of transformers will make the model’s parameters very large, which occupies a large amount of [...] Read more.
Due to the excellent results achieved by transformers in computer vision, more and more scholars have introduced transformers into the field of medical image segmentation. However, the use of transformers will make the model’s parameters very large, which occupies a large amount of the computer’s resources, making them very time-consuming during training. In order to alleviate this disadvantage, this paper explores a flexible and efficient search strategy that can find the best subnet from a continuous transformer network. The method is based on a learnable and uniform L1 sparsity constraint, which contains factors that reflect the global importance of the continuous search space in different dimensions, while the search process is simple and efficient, containing a single round of training. At the same time, in order to compensate for the loss of accuracy caused by the search, a pixel classification module is introduced into the model to compensate for the loss of accuracy in the model search process. Our experiments show that the model in this paper compresses 30% of the parameters and FLOPs used, while also showing a slight increase in the accuracy of the model on the Automatic Cardiac Diagnosis Challenge (ACDC) dataset. Full article
(This article belongs to the Section Medical Imaging)
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