Artificial Intelligence in Gastric Cancer Imaging With Emphasis on Diagnostic Imaging and Body Morphometry

Gastric cancer remains a significant global health concern, coercing the need for advancements in imaging techniques for ensuring accurate diagnosis and effective treatment planning. Artificial intelligence (AI) has emerged as a potent tool for gastric-cancer imaging, particularly for diagnostic imaging and body morphometry. This review article offers a comprehensive overview of the recent developments and applications of AI in gastric cancer imaging. We investigated the role of AI imaging in gastric cancer diagnosis and staging, showcasing its potential to enhance the accuracy and efficiency of these crucial aspects of patient management. Additionally, we explored the application of AI body morphometry specifically for assessing the clinical impact of gastrectomy. This aspect of AI utilization holds significant promise for understanding postoperative changes and optimizing patient outcomes. Furthermore, we examine the current state of AI techniques for the prognosis of patients with gastric cancer. These prognostic models leverage AI algorithms to predict long-term survival outcomes and assist clinicians in making informed treatment decisions.However, the implementation of AI techniques for gastric cancer imaging has several limitations. As AI continues to evolve, we hope to witness the translation of cutting-edge technologies into routine clinical practice, ultimately improving patient care and outcomes in the fight against gastric cancer.

Appendiceal Visualization on 2-mSv CT vs. Conventional-Dose CT in Adolescents and Young Adults with Suspected Appendicitis: An Analysis of Large Pragmatic Randomized Trial Data

Objective@#We compared appendiceal visualization on 2-mSv CT vs. conventional-dose CT (median 7 mSv) in adolescents and young adults and analyzed the undesirable clinical and diagnostic outcomes that followed appendiceal nonvisualization. @*Materials and Methods@#A total of 3074 patients aged 15–44 years (mean ± standard deviation, 28 ± 9 years; 1672 female) from 20 hospitals were randomized to the 2-mSv CT or conventional-dose CT group (1535 vs. 1539) from December 2013 through August 2016. A total of 161 radiologists from 20 institutions prospectively rated appendiceal visualization (grade 0, not identified; grade 1, unsure or partly visualized; and grade 2, clearly and entirely visualized) and the presence of appendicitis in these patients. The final diagnosis was based on CT imaging and surgical, pathologic, and clinical findings. We analyzed undesirable clinical or diagnostic outcomes, such as negative appendectomy, perforated appendicitis, more extensive than simple appendectomy, delay in patient management, or incorrect CT diagnosis, which followed appendiceal nonvisualization (defined as grade 0 or 1) and compared the outcomes between the two groups. @*Results@#In the 2-mSv CT and conventional-dose CT groups, appendiceal visualization was rated as grade 0 in 41 (2.7%) and 18 (1.2%) patients, respectively; grade 1 in 181 (11.8%) and 81 (5.3%) patients, respectively; and grade 2 in 1304 (85.0%) and 1421 (92.3%) patients, respectively (p < 0.001). Overall, undesirable outcomes were rare in both groups. Compared to the conventional-dose CT group, the 2-mSv CT group had slightly higher rates of perforated appendicitis (1.1% [17] vs. 0.5% [7], p = 0.06) and false-negative diagnoses (0.4% [6] vs. 0.0% [0], p = 0.01) following appendiceal nonvisualization. Otherwise, these two groups were comparable. @*Conclusion@#The use of 2-mSv CT instead of conventional-dose CT impairs appendiceal visualization in more patients. However, appendiceal nonvisualization on 2-mSv CT rarely leads to undesirable clinical or diagnostic outcomes.

Reliability of Skeletal Muscle Area Measurement on CT with Different Parameters: A Phantom Study

Objective@#To evaluate the reliability of CT measurements of muscle quantity and quality using variable CT parameters. @*Materials and Methods@#A phantom, simulating the L2–4 vertebral levels, was used for this study. CT images were repeatedly acquired with modulation of tube voltage, tube current, slice thickness, and the image reconstruction algorithm. Reference standard muscle compartments were obtained from the reference maps of the phantom. Cross-sectional area based on the Hounsfield unit (HU) thresholds of muscle and its components, and the mean density of the reference standard muscle compartment, were used to measure the muscle quantity and quality using different CT protocols. Signal-to-noise ratios (SNRs) were calculated in the images acquired with different settings. @*Results@#The skeletal muscle area (threshold, -29 to 150 HU) was constant, regardless of the protocol, occupying at least 91.7% of the reference standard muscle compartment. Conversely, normal attenuation muscle area (30–150 HU) was not constant in the different protocols, varying between 59.7% and 81.7% of the reference standard muscle compartment. The mean density was lower than the target density stated by the manufacturer (45 HU) in all cases (range, 39.0–44.9 HU). The SNR decreased with low tube voltage, low tube current, and in sections with thin slices, whereas it increased when the iterative reconstruction algorithm was used. @*Conclusion@#Measurement of muscle quantity using HU threshold was reliable, regardless of the CT protocol used. Conversely, the measurement of muscle quality using the mean density and narrow HU thresholds were inconsistent and inaccurate across different CT protocols. Therefore, further studies are warranted in future to determine the optimal CT protocols for reliable measurements of muscle quality.

Comprehensive Updates in the Role of Imaging for Multiple Myeloma Management Based on Recent International Guidelines

The diagnostic and treatment methods of multiple myeloma (MM) have been rapidly evolving owing to advances in imaging techniques and new therapeutic agents. Imaging has begun to play an important role in the management of MM, and international guidelines are frequently updated. Since the publication of 2015 International Myeloma Working Group (IMWG) criteria for the diagnosis of MM, whole-body magnetic resonance imaging (MRI) or low-dose whole-body computed tomography (CT) and 18F-fluorodeoxyglucose positron emission tomography/CT have entered the mainstream as diagnostic and treatment response assessment tools. The 2019 IMWG guidelines also provide imaging recommendations for various clinical settings. Accordingly, radiologists have become a key component of MM management. In this review, we provide an overview of updates in the MM field with an emphasis on imaging modalities.

Effects of Contrast Phases on Automated Measurements of Muscle Quantity and Quality Using CT

Objective@#Muscle quantity and quality can be measured with an automated system on CT. However, the effects of contrast phases on the muscle measurements have not been established, which we aimed to investigate in this study. @*Materials and Methods@#Muscle quantity was measured according to the skeletal muscle area (SMA) measured by a convolutional neural network-based automated system at the L3 level in 89 subjects undergoing multiphasic abdominal CT comprising unenhanced phase, arterial phase, portal venous phase (PVP), or delayed phase imaging. Muscle quality was analyzed using the mean muscle density and the muscle quality map, which comprises normal and low-attenuation muscle areas (NAMA and LAMA, respectively) based on the muscle attenuation threshold. The SMA, mean muscle density, NAMA, and LAMA were compared between PVP and other phases using paired t tests. Bland-Altman analysis was used to evaluate the inter-phase variability between PVP and other phases. Based on the cutoffs for low muscle quantity and quality, the counts of individuals who scored lower than the cutoff values were compared between PVP and other phases. @*Results@#All indices showed significant differences between PVP and other phases (p < 0.001 for all). The SMA, mean muscle density, and NAMA increased during the later phases, whereas LAMA decreased during the later phases. Bland-Altman analysis showed that the mean differences between PVP and other phases ranged -2.1 to 0.3 cm2 for SMA, -12.0 to 2.6 cm2 for NAMA, and -2.2 to 9.9 cm2 for LAMA.The number of patients who were categorized as low muscle quantity did not significant differ between PVP and other phases (p ≥ 0.5), whereas the number of patients with low muscle quality significantly differed (p ≤ 0.002). @*Conclusion@#SMA was less affected by the contrast phases. However, the muscle quality measurements changed with the contrast phases to greater extents and would require a standardization of the contrast phase for reliable measurement.

Reliability of Skeletal Muscle Area Measurement on CT with Different Parameters: A Phantom Study

Objective@#To evaluate the reliability of CT measurements of muscle quantity and quality using variable CT parameters. @*Materials and Methods@#A phantom, simulating the L2–4 vertebral levels, was used for this study. CT images were repeatedly acquired with modulation of tube voltage, tube current, slice thickness, and the image reconstruction algorithm. Reference standard muscle compartments were obtained from the reference maps of the phantom. Cross-sectional area based on the Hounsfield unit (HU) thresholds of muscle and its components, and the mean density of the reference standard muscle compartment, were used to measure the muscle quantity and quality using different CT protocols. Signal-to-noise ratios (SNRs) were calculated in the images acquired with different settings. @*Results@#The skeletal muscle area (threshold, -29 to 150 HU) was constant, regardless of the protocol, occupying at least 91.7% of the reference standard muscle compartment. Conversely, normal attenuation muscle area (30–150 HU) was not constant in the different protocols, varying between 59.7% and 81.7% of the reference standard muscle compartment. The mean density was lower than the target density stated by the manufacturer (45 HU) in all cases (range, 39.0–44.9 HU). The SNR decreased with low tube voltage, low tube current, and in sections with thin slices, whereas it increased when the iterative reconstruction algorithm was used. @*Conclusion@#Measurement of muscle quantity using HU threshold was reliable, regardless of the CT protocol used. Conversely, the measurement of muscle quality using the mean density and narrow HU thresholds were inconsistent and inaccurate across different CT protocols. Therefore, further studies are warranted in future to determine the optimal CT protocols for reliable measurements of muscle quality.

Comprehensive Updates in the Role of Imaging for Multiple Myeloma Management Based on Recent International Guidelines

The diagnostic and treatment methods of multiple myeloma (MM) have been rapidly evolving owing to advances in imaging techniques and new therapeutic agents. Imaging has begun to play an important role in the management of MM, and international guidelines are frequently updated. Since the publication of 2015 International Myeloma Working Group (IMWG) criteria for the diagnosis of MM, whole-body magnetic resonance imaging (MRI) or low-dose whole-body computed tomography (CT) and 18F-fluorodeoxyglucose positron emission tomography/CT have entered the mainstream as diagnostic and treatment response assessment tools. The 2019 IMWG guidelines also provide imaging recommendations for various clinical settings. Accordingly, radiologists have become a key component of MM management. In this review, we provide an overview of updates in the MM field with an emphasis on imaging modalities.

Using 2-mSv Appendiceal CT in Usual Practice for Adolescents and Young Adults: Willingness Survey of 579 Radiologists, Emergency Physicians, and Surgeons from 20 Hospitals

Structured Reporting versus Free-Text Reporting for Appendiceal Computed Tomography in Adolescents and Young Adults: Preference Survey of 594 Referring Physicians, Surgeons, and Radiologists from 20 Hospitals

OBJECTIVE: To survey care providers' preference between structured reporting (SR) and free-text reporting (FTR) for appendiceal computed tomography (CT) in adolescents and young adults. MATERIALS AND METHODS: An ethical committee approved this prospective study. The requirement for participant consent was waived. We distributed the Likert scale-based SR form delivering the likelihood of appendicitis across 20 hospitals through a large clinical trial. In the final phase of the trial, we invited 706 potential care providers to participate in an online survey. The survey questions included usefulness in patient management, communicating the likelihood of appendicitis, convenience, style and format, and overall preference. Logistic regression analysis was performed for the overall preference. Three months after the completion of the trial, we checked if the use of the SR was sustained. RESULTS: Responses were analyzed from 594 participants (175 attendings and 419 trainees; 225 radiologists, 207 emergency physicians, and 162 surgeons). For each question, 47.3–64.8% of the participants preferred SR, 13.1–32.7% preferred FTR, and the remaining had no preference. The overall preference varied considerably across the hospitals, but slightly across the departments or job positions. The overall preference for SR over FTR was significantly associated with attendings, SR experience for appendiceal CT, hospitals with small appendectomy volume, and hospitals enrolling more patients in the trial. Five hospitals continued using the SR in usual care after the trial. CONCLUSION: Overall, the care providers preferred SR to FTR. Further investigation into the sustained use of the SR is needed.

Letter to the Editor: Sharing Image Data from Clinical Trials

No abstract available.

Meaningful standard of reference for appendiceal perforation: pathology, surgery, or both?

PURPOSE: This retrospective study was aimed to determine if appendiceal perforation identified pathologically but not surgically is clinically meaningful. METHODS: The study consists of 2 parts. First, we reviewed 74 studies addressing appendiceal perforation published in 2012 and 2013. Second, in a cross-sectional study, we classified 1,438 adolescents and adults (mean age, 29.3 ± 8.4 years; 785 men) with confirmed appendicitis as “nonperforation” (n = 1,083, group 1), “pathologically-identified perforation” (n = 55, group 2), “surgically-identified perforation” (n = 202, group 3), or “pathologically- and surgically-identified perforation” (n = 98, group 4). The 4 groups were compared for the frequency of laparoscopic appendectomy and the length of hospital stay using multivariable logistic regression analyses. RESULTS: The reference standard for appendiceal perforation was frequently missing or inconsistent in the previous studies. Laparoscopic appendectomies were less frequent in groups 3 (52.5%, P = 0.001) and 4 (65%, P = 0.040) than in group 1 (70.7%), while group 2 (73%, P = 0.125) did not significantly differ from group 1. Median hospital stays were 2.9, 3.0, 5.1, and 6.0 days for groups 1–4, respectively. Prolonged hospital stay (≥3.7 days) was more frequent in groups 3 (77.7%, P < 0.001) and 4 (89%, P < 0.001) than in group 1 (23.4%), while group 2 (35%, P = 0.070) did not significantly differ from group 1. CONCLUSION: We recommend using surgical rather than pathologic findings as the reference standard for the presence of appendiceal perforation in future investigations.