The history of MR imaging as seen through the pages of radiology

Repurposing General Anesthetic Drugs to Treat Depression: A New Frontier for Anesthesiologists in Neuropsychiatric Care

During the last 100 years, the role of anesthesiologists in psychiatry has focused primarily on facilitating electroconvulsive therapy and mitigating postoperative delirium and other perioperative neurocognitive disorders. The discovery of the rapid and sustained antidepressant properties of ketamine, and early results suggesting that other general anesthetic drugs (including nitrous oxide, propofol, and isoflurane) have antidepressant properties, has positioned anesthesiologists at a new frontier in the treatment of neuropsychiatric disorders. Moreover, shared interest in understanding the biologic underpinnings of anesthetic drugs as psychotropic agents is eroding traditional academic boundaries between anesthesiology and psychiatry. This article presents a brief overview of anesthetic drugs as novel antidepressants and identifies promising future candidates for the treatment of depression. The authors issue a call to action and outline strategies to foster collaborations between anesthesiologists and psychiatrists as they work toward the common goals of repurposing anesthetic drugs as antidepressants and addressing mood disorders in surgical patients.

Aqueductal developmental venous anomaly causing obstructive hydrocephalus: A case report and review of the literature

A developmental venous anomaly (DVA) is a venous drainage of the associated parenchyma that is normally asymptomatic. However, a DVA located adjacent to the aqueduct can cause obstructive hydrocephalus by blocking the flow of cerebrospinal fluid. We describe a rare case of obstructive hydrocephalus due to aqueductal stenosis secondary to a DVA. A 43-year-old man presented with sudden bilateral temporal pain during weight training. Using a 3-Tesla scanner, cranial magnetic resonance imaging (MRI) was performed, and hydrocephalus was found with mild enlargement of the lateral and third ventricles. Susceptibility-weighted imaging and postcontrast MRI revealed that the DVA from the bilateral thalami narrowed the orifice of the aqueduct on its drainage route towards the vein of Galen. We assumed that force exerted during weight training may have caused dilation of the anomalous veins, leading to his symptom. A review of the relevant English-language literature yielded only 19 cases of aqueductal stenosis due to DVA. In comparison to these cases, the duration of symptom in our case was extremely short because the patient had a history of ventriculomegaly detected on plain computed tomography and was diagnosed quickly based on the characteristic finding of DVA: the caput medusae appearance.

Update on Optimization of Prostate MR Imaging Technique and Image Quality

Prostate MR imaging quality has improved dramatically over recent times, driven by advances in hardware, software, and improved functional imaging techniques. MRI now plays a key role in prostate cancer diagnostic work-up, but outcomes of the MRI-directed pathway are heavily dependent on image quality and optimization. MR sequences can be affected by patient-related degradations relating to motion and susceptibility artifacts which may enable only partial mitigation. In this Review, we explore issues relating to prostate MRI acquisition and interpretation, mitigation strategies at a patient and scanner level, PI-QUAL reporting, and future directions in image quality, including artificial intelligence solutions.

MRI scarcity in low- and middle-income countries

Since the introduction of MRI as a sustainable diagnostic modality, global accessibility to its services has revealed a wide discrepancy between populations-leaving most of the population in LMICs without access to this important imaging modality. Several factors lead to the scarcity of MRI in LMICs; for example, inadequate infrastructure and the absence of a dedicated workforce are key factors in the scarcity observed. RAD-AID has contributed to the advancement of radiology globally by collaborating with our partners to make radiology more accessible for medically underserved communities. However, progress is slow and further investment is needed to ensure improved global access to MRI.

Radiologist age and diagnostic errors

PURPOSE

Previous investigations into the causes of error by radiologists have addressed work schedule, volume, shift length, and sub-specialization. Studies regarding possible associations between radiologist errors and radiologist age and timing of residency training are lacking in the literature, to our knowledge. The aim of our study was to determine if radiologist age and residency graduation date is associated with diagnostic errors.

METHODS

Our retrospective analysis included 1.9 million preliminary interpretations (out of a total of 5.2 million preliminary and final interpretations) of imaging examinations by 361 radiologists in a US-based national teleradiology practice between 1/1/2019 and 1/1/2020. Quality assurance data regarding the number of radiologist errors was generated through client facility feedback to the teleradiology practice. With input from both the client radiologist and the teleradiologist, the final determination of the presence, absence, and severity of a teleradiologist error was determined by the quality assurance committee of radiologists within the teleradiology company using standardized criteria. Excluded were 3.2 million final examination interpretations and 93,963 (1.8%) of total examinations from facilities reporting less than one discrepancy in examination interpretation in 2019. Logistic regression with covariates radiologist age and residency graduation date was performed for calculation of relative risk of overall error rates and by major imaging modality. Major errors were separated from minor errors as those with a greater likelihood of affecting patient care. Logistic regression with covariates radiologist age, residency graduation date, and log total examinations interpreted was used to calculate odds of making a major error to that of making a minor error.

RESULTS

Mean age of the 361 radiologists was 51.1 years, with a mean residency graduation date of 2001. Mean error rate for all examinations was 0.5%. Radiologist age at any residency graduation date was positively associated with major errors (p < 0.05), with a relative risk 1.021 for each 1-year increase in age and relative risk 1.235 for each decade as well as for minor errors (p < 0.05, relative risk 1.007 for each year, relative risk 1.082 for each decade). By major imaging modality, radiologist age at any residency graduation date was positively associated with computed tomography (CT) and X-ray (XR) major and minor error, magnetic resonance imaging (MRI) major error, and ultrasound (US) minor error (p < 0.05). Radiologist age was positively associated with odds of making a major vs. minor error (p < 0.05).

CONCLUSIONS

The mean error rate for all radiologists was low. We observed that increasing age at any residency graduation date was associated with increasing relative risk of major and minor errors as well as increasing odds of a major vs. minor error among providers. Further study is needed to corroborate these results, determine clinical relevance, and highlight strategies to address these findings.

Magnetic resonance imaging using a nonuniform Bo (NuBo) field-cycling magnet

Magnetic resonance imaging (MRI) is a powerful noninvasive diagnostic tool with superior soft tissue contrast. However, access to MRI is limited since current systems depend on homogeneous, high field strength main magnets (B0-fields), with strong switchable gradients which are expensive to install and maintain. In this work we propose a new approach to MRI where imaging is performed in an inhomogeneous field using radiofrequency spatial encoding, thereby eliminating the need for uniform B0-fields and conventional cylindrical gradient coils. The proposed technology uses an innovative data acquisition and reconstruction approach by integrating developments in field cycling, parallel imaging and non-Fourier based algebraic reconstruction. The scanner uses field cycling to image in an inhomogeneous B0-field; in this way magnetization is maximized during the high field polarization phase, and B0 inhomogeneity effects are minimized by using a low field during image acquisition. In addition to presenting the concept, this work provides experimental verification of a long-lived spin echo signal, spatially varying resolution, as well as both simulated and experimental 2D images. Our initial design creates an open MR system that can be installed in a patient examination table for body imaging (e.g., breast or liver) or built into a wall for weighted-spine imaging. The proposed system introduces a new class of inexpensive, open, silent MRIs that could be housed in doctor's offices much like ultrasound is today, making MRI more widely accessible.

No Meta-analytic Evidence for Risks due to Prenatal Magnetic Resonance Imaging in Animal Models

BACKGROUND

Magnetic resonance imaging (MRI) is a powerful, noninvasive tool for both clinical practice and research. Though the safety of MRI has been endorsed by many professional societies and government bodies, some concerns have remained about potential risk from prenatal MRI. Case-control animal studies of MRI scanning during gestation and effects on offspring are the most direct test available for potential risks. We performed a meta-analysis of extant animal studies of prenatal MRI examining reproductive and offspring outcomes.

METHODS

Relevant articles were identified through PubMed search and citation searching of known articles and review papers. Eighteen relevant studies were identified with case-control designs of prenatal scanning conducted in vivo with mammalian species using MRI-relevant field strength. Standardized mean difference effect sizes were analyzed across k = 81 outcomes assessed across 649 unexposed dams, 622 exposed dams, 3024 unexposed offspring, and 3328 exposed offspring using a multilevel meta-analytic approach that clustered effect sizes within publications.

RESULTS

The meta-analysis indicated no significant evidence for a deleterious effects of prenatal MRI (standardized mean difference = 0.17, 95% CI [-0.19, 0.54], t80 = 0.94, p = .35) across outcomes. Similarly, no effects were observed when separately examining the 4 most commonly assessed outcomes: birth weight, litter size, fetal viability, and physical malformations (p > .05).

CONCLUSIONS

Case-control mammalian animal studies indicate no significant known risks of prenatal MRI to reproductive outcomes or offspring development. This finding is largely mirrored in human research, though the lack of randomized case-control designs limits direct comparison. The current findings provide additional support to the prevailing consensus that prenatal MRI poses no known risk to offspring.

Characterizing Cochlear Implant Magnet-Related MRI Artifact

OBJECTIVE

To evaluate cochlear implant (CI) magnet-related MRI artifact shape and size, as well as imaging indications and clinical adequacy of scans.

METHODS

A retrospective chart review was performed for patients undergoing CI and subsequent MRI head imaging from 2014 to 2020 at a single institution. Indications and adequacy of each scan was recorded, and interpretability compared by indication. Magnet-related artifact size was determined by performing ellipsoid modeling at axial slice of greatest signal loss. Artifact radius in centimeters was calculated for 5 sequence categories, and size compared between sequences, manufacturers, and by time from implantation.

RESULTS

Twenty patients underwent 58 head MRI scans. Approximately 76% of MRIs (n = 44) for 70% of patients (n = 14) were performed for indications known of prior to implantation; the remainder were performed during workup of new issues. Desired structures were interpretable in 23 (52%) of known-indication MRIs and 8 (57%) of new-indication MRIs, without significant difference (P = .751). Magnet-related artifact magnitude, compared to the reference T1-weighted fast spin echo (FSE) (4.47 cm), was similar in T2 FSE (4.57 cm, P = .068) and T1 gradient echo (GRE) sequences (4.79 cm, P = .28), but significantly greater in T2 GRE (6.86, P < .0001) and DWI (7.56 cm, P < .0001) sequences.

CONCLUSIONS

DWI and T2 GRE sequences are less useful in MRI evaluation of CI patients. With a more favorable artifact profile, T1 FSE, T2 FSE, and T1 GRE sequences more likely yield clinically useful information. The large proportion of scans performed for known pathology represents an opportunity to optimize for magnet location preoperatively.

Artificial Intelligence and Radiology Education

Implementation of artificial intelligence (AI) applications into clinical practice requires AI-savvy radiologists to ensure the safe, ethical, and effective use of these systems for patient care. Increasing demand for AI education reflects recognition of the translation of AI applications from research to clinical practice, with positive trainee attitudes regarding the influence of AI on radiology. However, barriers to AI education, such as limited access to resources, predispose to insufficient preparation for the effective use of AI in practice. In response, national organizations have sponsored formal and self-directed learning courses to provide introductory content on imaging informatics and AI. Foundational courses, such as the National Imaging Informatics Course - Radiology and the Radiological Society of North America Imaging AI Certificate, lay a framework for trainees to explore the creation, deployment, and critical evaluation of AI applications. This report includes additional resources for formal programming courses, video series from leading organizations, and blogs from AI and informatics communities. Furthermore, the scope of "AI and radiology education" includes AI-augmented radiology education, with emphasis on the potential for "precision education" that creates personalized experiences for trainees by accounting for varying learning styles and inconsistent, possibly deficient, clinical case volume. © RSNA, 2022 Keywords: Use of AI in Education, Impact of AI on Education, Artificial Intelligence, Medical Education, Imaging Informatics, Natural Language Processing, Precision Education.

Low-field MRI: Clinical promise and challenges

Modern MRI scanners have trended toward higher field strengths to maximize signal and resolution while minimizing scan time. However, high-field devices remain expensive to install and operate, making them scarce outside of high-income countries and major population centers. Low-field strength scanners have drawn renewed academic, industry, and philanthropic interest due to advantages that could dramatically increase imaging access, including lower cost and portability. Nevertheless, low-field MRI still faces inherent limitations in image quality that come with decreased signal. In this article, we review advantages and disadvantages of low-field MRI scanners, describe hardware and software innovations that accentuate advantages and mitigate disadvantages, and consider clinical applications for a new generation of low-field devices. In our review, we explore how these devices are being or could be used for high acuity brain imaging, outpatient neuroimaging, MRI-guided procedures, pediatric imaging, and musculoskeletal imaging. Challenges for their successful clinical translation include selecting and validating appropriate use cases, integrating with standards of care in high resource settings, expanding options with actionable information in low resource settings, and facilitating health care providers and clinical practice in new ways. By embracing both the promise and challenges of low-field MRI, clinicians and researchers have an opportunity to transform medical care for patients around the world. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 6.

Mouse Brain MRI: Including In Vivo, Ex Vivo, and fcMRI for the Study of Microcephaly

With its sensitivity to soft tissue, MRI is a powerful tool for the study of the neuroanatomical manifestations of a variety of conditions, such as microcephaly-related morbidities that are not easily visualized by other imaging techniques, such as CT. In addition to structural imaging, more recently, researchers have found changes in brain function in a wide range of neurological conditions-highlighting the utility of MRI for the study of microcephaly.In this methods chapter, basic mouse preparation and the acquisition of data for in vivo anatomical MRI will be discussed. Additionally, we will provide our protocol for the perfusion and fixation of brain tissue with gadolinium contrast agent. Following that, the process of optimization of system parameters will be shown for anatomical imaging of in vivo and ex vivo brain tissue. Lastly, the chapter will detail a protocol for fcMRI along with a discussion of considerations specific to functional imaging.

Utilization of potato starch suspension for MR-microimaging in ex vivo mouse embryos

Magnetic resonance (MR) microimaging of the mouse embryo is a promising tool to noninvasively investigate the microstructure of the brain of a developing mouse. The proton-free fluid is used for the liquid surrounding the specimen in MR microimaging, but the potential issue of image quality remains due to the air bubbles on the specimen and the retained water proton in the curvature of the embryo. Furthermore, the specimen may move during the scanning, resulting in motion artifact. Here, we developed the new concept of the ex vivo microimaging protocol with the robust method using the potato starch-containing biological polymers. Potato starch suspension with PBS significantly reduced T1 and T2 signal intensity of the suspension and strongly suppressed the motion of the embryo. Furthermore, potato starch-PBS suspension is stable for long-time scanning at room temperature. These results indicate the utility of potato starch suspension for MR microimaging in mouse embryos.

Evolution and Revolution of Imaging Technologies in Neurosurgery

We understand only a small fraction of the events happening in our brains; therefore, despite all the progress made thus far, a whole array of questions remains. Nonetheless, neurosurgeons invented new tools to circumvent the challenges that had plagued their predecessors. With the manufacturing boom of the 20th century, technological innovations blossomed enabling the neuroscientific community to study and operate upon the living brain in finer detail and with greater precision while avoiding harm to the nervous system. The purpose of this chronological review is to 1) raise awareness among future neurosurgeons about the latest advances in the field, 2) become familiar with innovations such as augmented reality (AR) that should be included in education given their ready applicability in surgical training, and 3) be comfortable with customizing these technologies to real-life cases like in the case of mixed reality.

Fifty years of bone tumors

There have been enormous advances in the treatment of bone tumors over the past half-century. The most notable of these has been the transition from amputation as the standard of care to limb salvage surgery. This transition is the result of advances in imaging techniques, accurate diagnosis, systemic therapies (including chemotherapy), and prosthetic design for the reconstruction of musculoskeletal defects. Advances have also been made in the management of benign and metastatic bone tumors.

Iron-Based Magnetic Nanosystems for Diagnostic Imaging and Drug Delivery: Towards Transformative Biomedical Applications

The advancement of biomedicine in a socioeconomically sustainable manner while achieving efficient patient-care is imperative to the health and well-being of society. Magnetic systems consisting of iron based nanosized components have gained prominence among researchers in a multitude of biomedical applications. This review focuses on recent trends in the areas of diagnostic imaging and drug delivery that have benefited from iron-incorporated nanosystems, especially in cancer treatment, diagnosis and wound care applications. Discussion on imaging will emphasise on developments in MRI technology and hyperthermia based diagnosis, while advanced material synthesis and targeted, triggered transport will be the focus for drug delivery. Insights onto the challenges in transforming these technologies into day-to-day applications will also be explored with perceptions onto potential for patient-centred healthcare.

Enhanced Transrectal Ultrasound, Real-Time Sonoelastography, and Contrast-Enhanced Transrectal Ultrasound in Heavily Prescreened Chinese Men With Naive and Repetitive Biopsy: A Comparison of Detection Rate of Prostate Cancer Per Man and Per Lesion

ABSTRACT

Multiparametric magnetic resonance imaging and targeted biopsy have been widely accepted as the most accurate technique to detect localize prostate cancer. It is a time-consuming and expensive option and may not be widely available in China, making ultrasound the first choice for the detection of prostate cancer. In this current retrospective study, the diagnostic values of enhanced transrectal ultrasound, contrast-enhanced transrectal ultrasound, and real-time sonoelastography were evaluated. Symptomatic 315 men older than 40 years with prostate-specific antigen level greater than 4.0 ng/mL, with abnormal digital rectal examinations, and with suspicious lesions for prostate cancer under enhanced transrectal ultrasound included in the study. Enhanced transrectal ultrasound was suspicious in all 315 men, with 189 of 315 men with prostate cancer according to the prostate biopsy report. Sonoelastography was suspicious in 294 of 315 men, with 166 of 315 men with prostate cancer according to the prostate biopsy report. Contrast-enhanced transrectal ultrasound was suspicious in 221 of 315 men, with 159 of 315 men with prostate cancer according to the prostate biopsy report. Real-time sonoelastography alone and contrast-enhanced transrectal ultrasound alone were missed in 27 (11%) and 39 (15%) lesions to report cancer through biopsies. Working area for enhanced transrectal ultrasound, real-time sonoelastography, and contrast-enhanced transrectal ultrasound for detection of prostate cancer were 0 to 1 diagnostic confidence, 0.11 to 0.895 diagnostic confidence, and 0.39 to 0.63 diagnostic confidence respectively. Real-time sonoelastography and contrast-enhanced transrectal ultrasound may improve the detection of prostate cancer in men with suspicious prostate lesions under enhanced transrectal ultrasound (Level of Evidence: III; Technical Efficacy Stage: 2).

Brain Tumor Characterization Using Radiogenomics in Artificial Intelligence Framework

Brain tumor characterization (BTC) is the process of knowing the underlying cause of brain tumors and their characteristics through various approaches such as tumor segmentation, classification, detection, and risk analysis. The substantial brain tumor characterization includes the identification of the molecular signature of various useful genomes whose alteration causes the brain tumor. The radiomics approach uses the radiological image for disease characterization by extracting quantitative radiomics features in the artificial intelligence (AI) environment. However, when considering a higher level of disease characteristics such as genetic information and mutation status, the combined study of "radiomics and genomics" has been considered under the umbrella of "radiogenomics". Furthermore, AI in a radiogenomics' environment offers benefits/advantages such as the finalized outcome of personalized treatment and individualized medicine. The proposed study summarizes the brain tumor's characterization in the prospect of an emerging field of research, i.e., radiomics and radiogenomics in an AI environment, with the help of statistical observation and risk-of-bias (RoB) analysis. The PRISMA search approach was used to find 121 relevant studies for the proposed review using IEEE, Google Scholar, PubMed, MDPI, and Scopus. Our findings indicate that both radiomics and radiogenomics have been successfully applied aggressively to several oncology applications with numerous advantages. Furthermore, under the AI paradigm, both the conventional and deep radiomics features have made an impact on the favorable outcomes of the radiogenomics approach of BTC. Furthermore, risk-of-bias (RoB) analysis offers a better understanding of the architectures with stronger benefits of AI by providing the bias involved in them.

Multi-nuclear magnetic resonance spectroscopy: state of the art and future directions

With the development of heteronuclear fluorine, sodium, phosphorus, and other probes and imaging technologies as well as the optimization of magnetic resonance imaging (MRI) equipment and sequences, multi-nuclear magnetic resonance (multi-NMR) has enabled localize molecular activities in vivo that are central to a variety of diseases, including cardiovascular disease, neurodegenerative pathologies, metabolic diseases, kidney, and tumor, to shift from the traditional morphological imaging to the molecular imaging, precision diagnosis, and treatment mode. However, due to the low natural abundance and low gyromagnetic ratios, the clinical application of multi-NMR has been hampered. Several techniques have been developed to amplify the NMR sensitivity such as the dynamic nuclear polarization, spin-exchange optical pumping, and brute-force polarization. Meanwhile, a wide range of nuclei can be hyperpolarized, such as ²H, ³He, ¹³C, ¹⁵ N, ³¹P, and ¹²⁹Xe. The signal can be increased and allows real-time observation of biological perfusion, metabolite transport, and metabolic reactions in vivo, overcoming the disadvantages of conventional magnetic resonance of low sensitivity. HP-NMR imaging of different nuclear substrates provides a unique opportunity and invention to map the metabolic changes in various organs without invasive procedures. This review aims to focus on the recent applications of multi-NMR technology not only in a range of preliminary animal experiments but also in various disease spectrum in human. Furthermore, we will discuss the future challenges and opportunities of this multi-NMR from a clinical perspective, in the hope of truly bridging the gap between cutting-edge molecular biology and clinical applications.

The Promise of Magnetic Resonance Imaging in Radiation Oncology Practice in the Management of Brain, Prostate, and GI Malignancies

Magnetic resonance imaging (MRI) has a key role to play at multiple steps of the radiotherapy (RT) treatment planning and delivery process. Development of high-precision RT techniques such as intensity-modulated RT, stereotactic ablative RT, and particle beam therapy has enabled oncologists to escalate RT dose to the target while restricting doses to organs at risk (OAR). MRI plays a critical role in target volume delineation in various disease sites, thus ensuring that these high-precision techniques can be safely implemented. Accurate identification of gross disease has also enabled selective dose escalation as a means to widen the therapeutic index. Morphological and functional MRI sequences have also facilitated an understanding of temporal changes in target volumes and OAR during a course of RT, allowing for midtreatment volumetric and biological adaptation. The latest advancement in linear accelerator technology has led to the incorporation of an MRI scanner in the treatment unit. MRI-guided RT provides the opportunity for MRI-only workflow along with online adaptation for either target or OAR or both. MRI plays a key role in post-treatment response evaluation and is an important tool for guiding decision making. In this review, we briefly discuss the RT-related applications of MRI in the management of brain, prostate, and GI malignancies.

Magnetic resonance imaging for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease

BACKGROUND

Hepatocellular carcinoma occurs mostly in people with chronic liver disease and ranks sixth in terms of global incidence of cancer, and third in terms of cancer deaths. In clinical practice, magnetic resonance imaging (MRI) is used as a second-line diagnostic imaging modality to confirm the presence of focal liver lesions suspected as hepatocellular carcinoma on prior diagnostic test such as abdominal ultrasound or alpha-fetoprotein, or both, either in surveillance programmes or in clinical settings. According to current guidelines, a single contrast-enhanced imaging study (computed tomography (CT) or MRI) showing typical hallmarks of hepatocellular carcinoma in people with cirrhosis is considered valid to diagnose hepatocellular carcinoma. The detection of hepatocellular carcinoma amenable to surgical resection could improve the prognosis. However, a significant number of hepatocellular carcinomas do not show typical hallmarks on imaging modalities, and hepatocellular carcinoma may, therefore, be missed. There is no clear evidence of the benefit of surveillance programmes in terms of overall survival: the conflicting results can be a consequence of inaccurate detection, ineffective treatment, or both. Assessing the diagnostic accuracy of MRI may clarify whether the absence of benefit could be related to underdiagnosis. Furthermore, an assessment of the accuracy of MRI in people with chronic liver disease who are not included in surveillance programmes is needed for either ruling out or diagnosing hepatocellular carcinoma.

OBJECTIVES

Primary: to assess the diagnostic accuracy of MRI for the diagnosis of hepatocellular carcinoma of any size and at any stage in adults with chronic liver disease. Secondary: to assess the diagnostic accuracy of MRI for the diagnosis of resectable hepatocellular carcinoma in adults with chronic liver disease, and to identify potential sources of heterogeneity in the results.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Hepato-Biliary Group Diagnostic Test of Accuracy Studies Register, the Cochrane Library, MEDLINE, Embase, and three other databases to 9 November 2021. We manually searched articles retrieved, contacted experts, handsearched abstract books from meetings held during the last 10 years, and searched for literature in OpenGrey (9 November 2021). Further information was requested by e-mails, but no additional information was provided. No data was obtained through correspondence with investigators. We applied no language or document-type restrictions.

SELECTION CRITERIA

Studies assessing the diagnostic accuracy of MRI for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease, with cross-sectional designs, using one of the acceptable reference standards, such as pathology of the explanted liver and histology of resected or biopsied focal liver lesion with at least a six-month follow-up.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened studies, extracted data, and assessed the risk of bias and applicability concerns, using the QUADAS-2 checklist. We presented the results of sensitivity and specificity, using paired forest plots, and we tabulated the results. We used a hierarchical meta-analysis model where appropriate. We presented uncertainty of the accuracy estimates using 95% confidence intervals (CIs). We double-checked all data extractions and analyses.

MAIN RESULTS

We included 34 studies, with 4841 participants. We judged all studies to be at high risk of bias in at least one domain because most studies used different reference standards, often inappropriate to exclude the presence of the target condition, and the time interval between the index test and the reference standard was rarely defined. Regarding applicability, we judged 15% (5/34) of studies to be at low concern and 85% (29/34) of studies to be at high concern mostly owing to characteristics of the participants, most of whom were on waiting lists for orthotopic liver transplantation, and due to pathology of the explanted liver being the only reference standard. MRI for hepatocellular carcinoma of any size and stage: sensitivity 84.4% (95% CI 80.1% to 87.9%) and specificity 93.8% (95% CI 90.1% to 96.1%) (34 studies, 4841 participants; low-certainty evidence). MRI for resectable hepatocellular carcinoma: sensitivity 84.3% (95% CI 77.6% to 89.3%) and specificity 92.9% (95% CI 88.3% to 95.9%) (16 studies, 2150 participants; low-certainty evidence). The observed heterogeneity in the results remains mostly unexplained. The sensitivity analyses, which included only studies with clearly prespecified positivity criteria and only studies in which the reference standard results were interpreted without knowledge of the results of the index test, showed no variation in the results.

AUTHORS' CONCLUSIONS

We found that using MRI as a second-line imaging modality to diagnose hepatocellular carcinoma of any size and stage, 16% of people with hepatocellular carcinoma would be missed, and 6% of people without hepatocellular carcinoma would be unnecessarily treated. For resectable hepatocellular carcinoma, we found that 16% of people with resectable hepatocellular carcinoma would improperly not be resected, while 7% of people without hepatocellular carcinoma would undergo inappropriate surgery. The uncertainty resulting from the high risk of bias in the included studies and concerns regarding their applicability limit our ability to confidently draw conclusions based on our results.

A CNN Based Software Gradiometer for Electromagnetic Background Noise Reduction in Low Field MRI Applications

The shielding of electromagnetic noise is critical in obtaining magnetic resonance imaging measurements in the ultra-low magnetic field regime where the intrinsic signal-to-noise ratio is very small. The traditional approach of using an enclosure for electromagnetic shielding is expensive and hinders system portability. We describe here the use of a CNN-based software gradiometer to suppress the effect of electromagnetic ambient background noise sources that inductively couple into the signal detection coils. The system involves three ambient noise monitoring coils placed at a distance from the magnetic resonance signal detector. The three coils were used to synthesize the ambient noise captured by the signal detector; a convolutional neural network approach was used. Mathematical foundations are provided to justify the noise suppression framework. The results show that as much as 20-fold noise suppression can be achieved using an optimized convolutional neural network and simultaneous ambient noise measurements. The proposed approach has the potential to replace the requirement for magnetically shielded enclosures and make ultra-low field magnetic resonance imaging truly portable.

Bibliometric overview of the Top 100 most cited articles on hydrocephalus

Background:

Hydrocephalus is one of the most common brain disorders and numerous articles were published to address the clinical aspect and its management. This study aims to highlight the most influential work on hydrocephalus on bibliometric basis.

Methods:

A thorough search of Scopus database was performed using the word “hydrocephalus.” The 100 most cited articles were retrieved, and variables of importance were collected including the article’s title, 1^st author affiliation, country of origin, year and journal of publication, article’s category, and citation count according to Scopus and Google scholar databases.

Results:

The 100 most cited articles were thoroughly analyzed. Publication dates ranged from 1946 to 2014, with most articles (45) published between 1998 and 2007. The mean number of citations per publication was 201 with total of 20,177 citations. The United States of America contributed half of the articles. The leading institution was the Canadian hospital for Sick Children University of Toronto having published 5 articles. Hydrocephalus in general and normal pressure hydrocephalus was the two major categories addressed with most studies fall under the topic of surgical management. Neurosurgery was the specialty with the greatest contribution (47%). The articles were published in 46 different journals led by the Journal of Neurosurgery with total of 17 articles.

Conclusion:

This bibliometric analysis delineates the landmark publications in hydrocephalus. The listed articles depict the myriad of studied aspects historically which helps in understanding hydrocephalus overall in evidence-based module for neurosurgeons and non-neurosurgeons.

Cardiovascular Magnetic Resonance Imaging: A Prospective Modality in the Diagnosis and Prognostication of Heart Failure

Heart failure (HF) is a clinical syndrome resulting from structural cardiac remodeling and altered function that impairs tissue perfusion. This article aimed to highlight the current diagnostic and prognostic value of cardiac magnetic resonance (CMR) in the management of HF and prospective future applications. Reviewed are the physics associated with CMR, its use in ischemic and non-ischemic causes of HF, and its role in quantifying left ventricular ejection fraction. It also emphasized that CMR allows for noninvasive morphologic and functional assessment, tissue characterization, blood flow, and perfusion evaluation in patients with suspected or diagnosed HF. CMR has become a crucial instrument for the diagnosis, prognosis, and therapy planning in patients with HF and cardiomyopathy due to its accuracy in quantifying cardiac volumes and ejection fraction (considered the gold standard) as well as native and post-contrast myocardial tissue characterization.

Patient-Specific Inverse Modeling of In Vivo Cardiovascular Mechanics with Medical Image-Derived Kinematics as Input Data: Concepts, Methods, and Applications

Inverse modeling approaches in cardiovascular medicine are a collection of methodologies that can provide non-invasive patient-specific estimations of tissue properties, mechanical loads, and other mechanics-based risk factors using medical imaging as inputs. Its incorporation into clinical practice has the potential to improve diagnosis and treatment planning with low associated risks and costs. These methods have become available for medical applications mainly due to the continuing development of image-based kinematic techniques, the maturity of the associated theories describing cardiovascular function, and recent progress in computer science, modeling, and simulation engineering. Inverse method applications are multidisciplinary, requiring tailored solutions to the available clinical data, pathology of interest, and available computational resources. Herein, we review biomechanical modeling and simulation principles, methods of solving inverse problems, and techniques for image-based kinematic analysis. In the final section, the major advances in inverse modeling of human cardiovascular mechanics since its early development in the early 2000s are reviewed with emphasis on method-specific descriptions, results, and conclusions. We draw selected studies on healthy and diseased hearts, aortas, and pulmonary arteries achieved through the incorporation of tissue mechanics, hemodynamics, and fluid-structure interaction methods paired with patient-specific data acquired with medical imaging in inverse modeling approaches.

Clinical Spectroscopy: Lost in Translation?

This Focal Point Review paper discusses the developments of biomedical Raman and infrared spectroscopy, and the recent strive towards these technologies being regarded as reliable clinical tools. The promise of vibrational spectroscopy in the field of biomedical science, alongside the development of computational methods for spectral analysis, has driven a plethora of proof-of-concept studies which convey the potential of various spectroscopic approaches. Here we report a brief review of the literature published over the past few decades, with a focus on the current technical, clinical, and economic barriers to translation, namely the limitations of many of the early studies, and the lack of understanding of clinical pathways, health technology assessments, regulatory approval, clinical feasibility, and funding applications. The field of biomedical vibrational spectroscopy must acknowledge and overcome these hurdles in order to achieve clinical efficacy. Current prospects have been overviewed with comment on the advised future direction of spectroscopic technologies, with the aspiration that many of these innovative approaches can ultimately reach the frontier of medical diagnostics and many clinical applications.

Anatomical Engineering and 3D Printing for Surgery and Medical Devices: International Review and Future Exponential Innovations

Three-dimensional printing (3DP) has recently gained importance in the medical industry, especially in surgical specialties. It uses different techniques and materials based on patients' needs, which allows bioprofessionals to design and develop unique pieces using medical imaging provided by computed tomography (CT) and magnetic resonance imaging (MRI). Therefore, the Department of Biology and Medicine and the Department of Physics and Engineering, at the Bioastronautics and Space Mechatronics Research Group, have managed and supervised an international cooperation study, in order to present a general review of the innovative surgical applications, focused on anatomical systems, such as the nervous and craniofacial system, cardiovascular system, digestive system, genitourinary system, and musculoskeletal system. Finally, the integration with augmented, mixed, virtual reality is analyzed to show the advantages of personalized treatments, taking into account the improvements for preoperative, intraoperative planning, and medical training. Also, this article explores the creation of devices and tools for space surgery to get better outcomes under changing gravity conditions.

Multiparametric Functional MRI of the Kidney: Current State and Future Trends with Deep Learning Approaches

BACKGROUND

 Until today, assessment of renal function has remained a challenge for modern medicine. In many cases, kidney diseases accompanied by a decrease in renal function remain undetected and unsolved, since neither laboratory tests nor imaging diagnostics provide adequate information on kidney status. In recent years, developments in the field of functional magnetic resonance imaging with application to abdominal organs have opened new possibilities combining anatomic imaging with multiparametric functional information. The multiparametric approach enables the measurement of perfusion, diffusion, oxygenation, and tissue characterization in one examination, thus providing more comprehensive insight into pathophysiological processes of diseases as well as effects of therapeutic interventions. However, application of multiparametric fMRI in the kidneys is still restricted mainly to research areas and transfer to the clinical routine is still outstanding. One of the major challenges is the lack of a standardized protocol for acquisition and postprocessing including efficient strategies for data analysis. This article provides an overview of the most common fMRI techniques with application to the kidney together with new approaches regarding data analysis with deep learning.

METHODS

 This article implies a selective literature review using the literature database PubMed in May 2021 supplemented by our own experiences in this field.

RESULTS AND CONCLUSION

 Functional multiparametric MRI is a promising technique for assessing renal function in a more comprehensive approach by combining multiple parameters such as perfusion, diffusion, and BOLD imaging. New approaches with the application of deep learning techniques could substantially contribute to overcoming the challenge of handling the quantity of data and developing more efficient data postprocessing and analysis protocols. Thus, it can be hoped that multiparametric fMRI protocols can be sufficiently optimized to be used for routine renal examination and to assist clinicians in the diagnostics, monitoring, and treatment of kidney diseases in the future.

KEY POINTS

  · Multiparametric fMRI is a technique performed without the use of radiation, contrast media, and invasive methods.. · Multiparametric fMRI provides more comprehensive insight into pathophysiological processes of kidney diseases by combining functional and structural parameters.. · For broader acceptance of fMRI biomarkers, there is a need for standardization of acquisition, postprocessing, and analysis protocols as well as more prospective studies.. · Deep learning techniques could significantly contribute to an optimization of data acquisition and the postprocessing and interpretation of larger quantities of data..

CITATION FORMAT

· Zhang C, Schwartz M, Küstner T et al. Multiparametric Functional MRI of the Kidney: Current State and Future Trends with Deep Learning Approaches. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1775-8633.

Predictive MRI Biomarkers in MS—A Critical Review

Background and Objectives: In this critical review, we explore the potential use of MRI measurements as prognostic biomarkers in multiple sclerosis (MS) patients, for both conventional measurements and more novel techniques such as magnetization transfer, diffusion tensor, and proton spectroscopy MRI. Materials and Methods: All authors individually and comprehensively reviewed each of the aspects listed below in PubMed, Medline, and Google Scholar. Results: There are numerous MRI metrics that have been proven by clinical studies to hold important prognostic value for MS patients, most of which can be readily obtained from standard 1.5T MRI scans. Conclusions: While some of these parameters have passed the test of time and seem to be associated with a reliable predictive power, some are still better interpreted with caution. We hope this will serve as a reminder of how vast a resource we have on our hands in this versatile tool—it is up to us to make use of it.

Post-Acquisition Hyperpolarized 29Silicon Magnetic Resonance Image Processing for Visualization of Colorectal Lesions Using a User-Friendly Graphical Interface

Medical imaging devices often use automated processing that creates and displays a self-normalized image. When improperly executed, normalization can misrepresent information or result in an inaccurate analysis. In the case of diagnostic imaging, a false positive in the absence of disease, or a negative finding when disease is present, can produce a detrimental experience for the patient and diminish their health prospects and prognosis. In many clinical settings, a medical technical specialist is trained to operate an imaging device without sufficient background information or understanding of the fundamental theory and processes involved in image creation and signal processing. Here, we describe a user-friendly image processing algorithm that mitigates user bias and allows for true signal to be distinguished from background. For proof-of-principle, we used antibody-targeted molecular imaging of colorectal cancer (CRC) in a mouse model, expressing human MUC1 at tumor sites. Lesion detection was performed using targeted magnetic resonance imaging (MRI) of hyperpolarized silicon particles. Resulting images containing high background and artifacts were then subjected to individualized image post-processing and comparative analysis. Post-acquisition image processing allowed for co-registration of the targeted silicon signal with the anatomical proton magnetic resonance (MR) image. This new methodology allows users to calibrate a set of images, acquired with MRI, and reliably locate CRC tumors in the lower gastrointestinal tract of living mice. The method is expected to be generally useful for distinguishing true signal from background for other cancer types, improving the reliability of diagnostic MRI.

Pulmonary functional imaging (PFI): A historical review and perspective

PFI Pulmonary Functional Imaging (PFI) refers to visualization and measurement of ventilation, perfusion, gas flow and exchange as well as biomechanics. In this review, we will highlight the historical development of PFI, describing recent advances and listing the various techniques for PFI offered per modality. Challenges PFI is facing and requirements for PFI from a clinical point of view will be pointed out. Hereby the review is meant as an introduction to PFI.

Magnetic Resonance Imaging Basics

In this chapter, we will discuss the basic principles of signal generation and image formation in magnetic resonance imaging (MRI). We will start with a description of nuclear magnetic resonance (NMR) phenomenon and then gradually arrive at the mathematical expressions for MRI signal in spatial domain and k-space domain. Then we describe the image reconstruction methods typically used in MRI, the signal-to-noise ratio calculation methods in MRI, and common MR image formats. A key focus of the contents of this chapter is on the formation of phase images in MRI. We do not intend to provide a comprehensive overview of MRI. Instead, the contents are intended for readers interested in performing research in electromagnetic properties mapping using MRI. Nevertheless, considering the generality of the contents, any reader interested in developing a quick understanding of the physical and mathematical background of MRI can find this chapter helpful.

Neural correlates of compassion - An integrative systematic review

Compassion is a psychological construct that has received increasing attention in recent years. Even though a lot of work has been done to identify neural correlates of empathy across studies, such work has not been properly done on neural correlates of compassion. Therefore, the aim was to systematically review the literature on neural correlates of compassion. We have searched through PsycINFO, PubMed and Web of Science for relevant articles published between 1985 and 2020. We included the studies (n = 35) examining the relationship between brain structure or function and compassion. Screening was performed by two authors, between whom a level of agreement was calculated. The quality of the studies was assessed by measures used in other studies as well by measures specific for our study aims. This study was conducted under PRISMA guidelines. Our analysis revealed that the most frequent neural associations with compassion across all analysed studies can be found in the orbital part of the left inferior frontal gyrus, in the right cerebellum, the bilateral middle temporal gyrus, in the bilateral insula and the right caudate nucleus. Our findings suggest that people displaying a lower compassion tend to have either lower neural activity or a grey matter volume in neural areas associated with reward.

The Role of Magnetic Resonance Imaging to Inform Clinical Decision-Making in Acute Spinal Cord Injury: A Systematic Review and Meta-Analysis

The clinical indications and added value of obtaining MRI in the acute phase of spinal cord injury (SCI) remain controversial. This review aims to critically evaluate evidence regarding the role of MRI to influence decision-making and outcomes in acute SCI. A systematic review and meta-analysis were performed according to PRISMA methodology to identify studies that address six key questions (KQs) regarding diagnostic accuracy, frequency of abnormal findings, frequency of altered decision-making, optimal timing, and differences in outcomes related to obtaining an MRI in acute SCI. A total of 32 studies were identified that addressed one or more KQs. MRI showed no adverse events in 156 patients (five studies) and frequently identified cord compression (70%, 12 studies), disc herniation (43%, 16 studies), ligamentous injury (39%, 13 studies), and epidural hematoma (10%, two studies), with good diagnostic accuracy (seven comparative studies) except for fracture detection. MRI findings often altered management, including timing of surgery (78%, three studies), decision to operate (36%, 15 studies), and surgical approach (29%, nine studies). MRI may also be useful to determine the need for instrumentation (100%, one study), which levels to decompress (100%, one study), and if reoperation is needed (34%, two studies). The available literature consistently concluded that MRI was useful prior to surgical treatment (13 studies) and after surgery to assess decompression (two studies), but utility before/after closed reduction of cervical dislocations was unclear (three studies). One study showed improved outcomes with an MRI-based protocol but had a high risk of bias. Heterogeneity was high for most findings (I² > 0.75). MRI is safe and frequently identifies findings alter clinical management in acute SCI, although direct evidence of its impact on outcomes is lacking. MRI should be performed before and after surgery, when feasible, to facilitate improved clinical decision-making. However, further research is needed to determine its optimal timing, effect on outcomes, cost-effectiveness, and utility before and after closed reduction.

Neuroimaging at 3T vs 7T: Is It Really Worth It?

Food and Drug Administration approval of 7T MR imaging allows ultrahigh-field neuroimaging to extend from the research realm into the clinical realm. Increased signal is clinically advantageous for smaller voxels and thereby high spatial resolution imaging, with additional advantages of increased tissue contrast. Susceptibility, time-of-flight signal, and blood oxygen level-dependent signal also have favorable clinical benefit from 7T. This article provides a survey of clinical cases showcasing some advantages of 7T.

Magnetic Resonance Simulation in Education: Quantitative Evaluation of an Actual Classroom Experience

Magnetic resonance is an imaging modality that implies a high complexity for radiographers. Despite some simulators having been developed for training purposes, we are not aware of any attempt to quantitatively measure their educational performance. The present study gives an answer to the question: Does an MRI simulator built on specific functional and non-functional requirements help radiographers learn MRI theoretical and practical concepts better than traditional educational method based on lectures? Our study was carried out in a single day by a total of 60 students of a main hospital in Madrid, Spain. The experiment followed a randomized pre-test post-test design with a control group that used a traditional educational method, and an experimental group that used our simulator. Knowledge level was assessed by means of an instrument with evidence of validity in its format and content, while its reliability was analyzed after the experiment. Statistical differences between both groups were measured. Significant statistical differences were found in favor of the participants who used the simulator for both the post-test score and the gain (difference between post-test and pre-test scores). The effect size turned out to be significant as well. In this work we evaluated a magnetic resonance simulation paradigm as a tool to help in the training of radiographers. The study shows that a simulator built on specific design requirements is a valuable complement to traditional education procedures, backed up with significant quantitative results.

The Association of MRI Findings and Long-Term Disability in Patients With Chronic Low Back Pain

STUDY DESIGN

Longitudinal cohort study with 13-year follow-up.

OBJECTIVE

To assess whether long-term disability is associated with baseline degenerative magnetic resonance imaging (MRI) findings in patients with low back pain (LBP).

METHODS

In 2004-2005, patients aged 18 to 60 years with chronic LBP were enrolled in a randomized controlled trial and lumbar MRI was performed. Patients completed the Roland-Morris Disability Questionnaire (RMDQ) and the LBP Rating Scale, at baseline and 13 years after the MRI. Multivariate regression analysis was performed with 13-year RMDQ as the dependent variable and baseline disc degeneration (DD, Pfirrmann grade), Modic changes (MC), facet joint degeneration (FJD, Fujiwara grade) smoking status, body mass index, and self-reported weekly physical activity at leisure as independent variables.

RESULTS

Of 204 patients with baseline MRI, 170 (83%) were available for follow-up. Of these, 88 had Pfirrmann grade >III (52%), 67 had MC (39%) and 139 had Fujiwara grade >2 (82%) on at least 1 lumbar level. Only MC (β = -0.15, P = .031) and weekly physical activity at leisure (β = -0.51, P < .001) were significantly, negatively, associated with 13-year RMDQ-score (R² = 0.31).

CONCLUSION

DD and FJD were not associated with long-term disability. Baseline MC and weekly physical activity at leisure were statistically significantly associated with less long-term disability.

A guideline for 3D printing terminology in biomedical research utilizing ISO/ASTM standards

First patented in 1986, three-dimensional (3D) printing, also known as additive manufacturing or rapid prototyping, now encompasses a variety of distinct technology types where material is deposited, joined, or solidified layer by layer to create a physical object from a digital file. As 3D printing technologies continue to evolve, and as more manuscripts describing these technologies are published in the medical literature, it is imperative that standardized terminology for 3D printing is utilized. The purpose of this manuscript is to provide recommendations for standardized lexicons for 3D printing technologies described in the medical literature. For all 3D printing methods, standard general ISO/ASTM terms for 3D printing should be utilized. Additional, non-standard terms should be included to facilitate communication and reproducibility when the ISO/ASTM terms are insufficient in describing expository details. By aligning to these guidelines, the use of uniform terms for 3D printing and the associated technologies will lead to improved clarity and reproducibility of published work which will ultimately increase the impact of publications, facilitate quality improvement, and promote the dissemination and adoption of 3D printing in the medical community.

Trends in paediatric central nervous system tumour incidence by global region from 1988 to 2012

BACKGROUND

Central nervous system (CNS) tumours comprise 20% of childhood cancers worldwide. Whether childhood CNS tumour incidence has increased over time across geographic regions remains to be explored.

METHODS

We identified CNS cancers in the Cancer in Five Continents (CI5) data and estimated age standardized incidence rates (ASRs; cases/million children) and 95% confidence intervals (95% CI), male-to-female incidence rate ratios (IRR; 95% CI) and average annual percent change in incidence (AAPC; 95% CI) by geographic region for children aged 0-19 years where data were available using Poisson regression and generalized estimating equations (GEE). Cancers included: astrocytic tumours, medulloblastoma, ependymal, oligodendroglial and mixed glioma, glioma of uncertain origin, and other embryonal tumours. Geographic regions were defined using the United Nations geoscheme.

RESULTS

There were 56 468 CNS cancers included in the study. ASRs were highest for astrocytic tumours globally in 2012 (ASR: 5.83; 95% CI: 5.68-5.99). Globally, all cancers exhibited a male excess in incidence. Regionally, only medulloblastoma had a consistently elevated male-to-female IRR at 1.4-2.2. Globally, incidence decreased for astrocytic tumours in GEE models (AAPC: -1.66; 95% CI: -3.04 to -0.26) and increased for medulloblastoma (AAPC 0.66; 95% CI: 0.19-1.14), ependymal tumours (AAPC: 1.49; 95% CI: 1.49; 95%: 0.69-2.30), glioma of uncertain origin (AAPC: 4.76; 95% CI: 1.17-1.14) and other embryonal tumours (AAPC: 3.58; 95% CI: 2.03-5.15). Regional variation in incidence trends was observed. Countries moving from lower to higher Human Development Index (HDI) over time did not appear to drive observed incidence trends.

CONCLUSIONS

Epidemiologic and molecular studies on underlying mechanisms for changes in the global incidence of CNS tumours are necessary.

Approaches in cooling of resistive coil-based low-field Magnetic Resonance Imaging (MRI) systems for application in low resource settings

Magnetic Resonance Imaging (MRI), a non-invasive method for the diagnosis of diverse health conditions has experienced growing popularity over other imaging modalities like ultrasound and Computer Tomography. Initially, proof-of-concept and earlier MRI systems were based on resistive and permanent magnet technology. However, superconducting magnets have long held monopoly of the market for MRI systems with their high-field (HF) strength capability, although they present high construction, installation, and siting requirements. Such stringent prerequisites restrict their availability and use in low-middle income countries. Resistive coil-based magnet, albeit low-field (LF) in capacity, represent a plausible boost for the availability and use of MRI systems in resource constrained settings. These systems are characterized by low costs coupled with substantial image quality for diagnosis of some conditions such as hydrocephalus common is such regions. However, the nature of resistive coils causes them to heat up during operation, thus necessitating a dedicated cooling system to improve image quality and enhance system longevity. This paper explores a range of cooling methods as have been applied to resistive magnets, citing their pros and cons and areas for improvement.

Tumor microenvironment-responsive multifunctional nanoplatform based on MnFe2O4-PEG for enhanced magnetic resonance imaging-guided hypoxic cancer radiotherapy

Radiotherapy occupies an essential position in curing and palliating a wide range of solid tumors based on DNA damage responses to eradicate cancer cells. However, the tumor microenvironment generally exhibits the characteristics of hypoxia and glutathione overexpression, which play a critical role in radioresistance, to prevent irreparable breaks to DNA and necrocytosis of cancer cells. Herein, polyethylene glycol (PEG) functionalized manganese ferrite nanoparticles (MnFe₂O₄-PEG) are designed to enable self-sufficiency of oxygen by continuously catalyzing the decomposition of endogenous hydrogen peroxide. Simultaneously, the nano-platform can consume GSH to reduce the loss of reactive oxygen species in radiotherapy and achieve better therapeutic effects at the cellular and animal levels. In addition, the MnFe₂O₄-PEG could act as an optimal T₁- and T₂-weighted contrast medium for tumor-specific magnetic resonance imaging. This work proposes a systematically administered radiosensitizer that can selectively reside in tumor sites via the enhanced permeability and retention effect to relieve hypoxia and reduce GSH concentration, combined with dual-mode magnetic resonance imaging, achieving precise and effective image-guided tumor therapy.

Incidentally detected acromegaly: single-center study of surgically treated patients over 22 years

Acromegaly is a rare disease associated with comorbidities that are common in the general population. Most patients undergo screening for classic phenotypical (CP) or mass effect manifestations. By retrospective review of pituitary tumor surgeries performed between 1994 and 2016 (1836), we identified patients with acromegaly (112). Main presentations were: CP (43%), mass effect (26%), incidentally detected (ID) tumors (17%), and other (14%). We compared the ID and CP groups regarding prevalence, clinical, biochemical, radiological and histopathological characteristics, and postoperative outcomes. The prevalence of ID among all surgeries increased after 2011 from 0.6% to 1.9% (p=0.01), while prevalence of CP remained stable (2.8% and 2.33%, p=0.65). Almost half of ID (47.4%) presented with otolaryngological manifestations. The ID and CP groups were similar regarding age, gender, comorbidities (hypertension, diabetes, hypopituitarism), tumor diameter and cavernous sinus invasion. Median insulin-like growth factor (IGF-1) and growth hormone (GH) levels were lower in the ID than CP (p<0.05 and p=0.07). Patients younger than 40 had smaller tumors in the ID than CP, while the opposite was true for older patients. The 3-month biochemical remission rates were similar (68% ID and 58% CP). A similar number of patients had normal IGF-1 at last follow-up (89.5% ID and 81.25% CP) after surgery alone and multimodality treatment. In conclusion, an increased number of patients with GH-secreting adenomas were ID in recent years. Education of physicians other than endocrinologists regarding presentation and comorbidity clustering may lead to an earlier diagnosis of acromegaly and improved outcomes.