Capturing the Unseen
By Rebecca Montz, EdD, MBA, CNMT, PET, RT(N)(CT), NMTCB RS
Radiology Today
Vol. 25 No. 3 P. 12

Opportunities in Opportunistic Imaging

Opportunistic imaging or opportunistic screening, a practice that entails identifying and utilizing supplementary imaging data beyond its initial intended purpose, has surfaced as a useful health care tool. This continuously evolving practice presents advantages and challenges, but the identification of unanticipated discoveries during routine imaging has unveiled new possibilities for improving patient care. Many health care providers are beginning to adopt this facet of medical imaging.

Matthew Lee, MD, an assistant professor in the department of radiology at the University of Wisconsin School of Medicine and Public Health, describes opportunistic imaging as a purposeful, resourceful practice of leveraging “incidental” imaging data. This data, which goes unused or underutilized in routine clinical practice, presents a unique opportunity to detect potentially important, clinically relevant diseases and markers of disease risk. Lee emphasizes that the early detection and identification of individuals at increased risk for cardiometabolic disease, osteoporosis, and cancer could lead to improved longevity, quality of life, and clinical outcomes if timely lifestyle modifications or other meaningful interventions can be implemented. Opportunistic imaging can be applied across various imaging modalities, encompassing X-rays, CT, MRI, and ultrasound. Additionally, integrating AI tools into opportunistic imaging has attracted significant attention.

Advantages of Opportunistic Imaging
Opportunistic imaging offers advantages for health care providers and patients. One of the primary advantages is the potential for early detection and diagnosis of medical conditions. It also contributes to a more comprehensive patient assessment by revealing unexpected health issues. This efficiency in gathering relevant information enhances the ability of health care providers to formulate accurate and timely diagnoses.

Incidental findings may lead to the identification of diseases at an early stage, enabling prompt intervention and improved patient outcomes. Lee says body CT and abdominal CT examinations, in particular, are essential parts of general and abdominal subspecialty radiology with immense potential for value-added opportunistic screening. The large volume of body CT scans performed is a testament to the clinical value and importance of CT as a diagnostic test and provides an opportunity for quantitative evaluation of tissues and body composition. This, in conjunction with fully automated AI body composition tools, allows for rapid and objective assessment of body composition, including abdominal muscle, fat, the liver, and vasculature, which several recent studies have shown can provide important insight into metabolic health and cardiometabolic disease, Lee says.

Fully automated and “explainable” AI tools applied to existing imaging examinations could enhance the effectiveness of opportunistic imaging endeavors without requiring additional testing, cost, or radiation exposure. This efficiency could help optimize resource utilization. Lee says the implementation of “value-added opportunistic imaging” has the capability to elevate the role and influence of radiology in population and public health. By leveraging imaging data unrelated to the clinical indication, opportunistic imaging could add value through disease prediction, enhanced health outcomes, and decreased costs, particularly for preventable diseases.

Opportunistic imaging findings can contribute valuable data to medical research, fostering advancements in understanding disease patterns, treatment responses, and health care outcomes. It also has significant potential to be a value-added initiative for individual and populationlevel impact, particularly if efforts are directed at the most important public health challenges, such as cardiometabolic disease and cancer. Thoughtful approaches to opportunistic screening for cardiovascular disease, osteoporosis, and sarcopenia also appear to be highly cost-effective and costsaving, as discussed by Pickhardt et al, in their article, “AI-Based Opportunistic CT Screening of Incidental Cardiovascular Disease, Osteoporosis, and Sarcopenia: Cost-Effectiveness Analysis.” The confluence of increasing clinical imaging volumes and the emergence of new technologies and AI tools offer a unique opportunity to expand the reach and impact of radiology within the population and public health through opportunistic imaging, Lee says.

Challenges and Considerations
Lee says challenges in adopting and implementing opportunistic imaging initiatives can be broadly classified into issues related to the adverse consequences of incidental imaging findings, resistance from imaging stakeholders (eg, radiologists, referring providers), technical challenges, commercial availability, and regulatory hurdles. Ethical concerns regarding patient consent and autonomy may arise in opportunistic imaging, emphasizing the need to strike a balance between acquiring additional information and respecting patient rights.

According to Lee, all imaging examinations carry the potential for incidental findings unrelated to the examination’s primary purpose. These findings have raised concerns about downstream cascades of costly, anxiety- inducing, and potentially harmful testing and procedures, leading to the development of consensus-based white papers and guidelines for management. Identifying incidental findings may also result in diagnosing conditions that may not have caused harm or required treatment, highlighting the importance of careful consideration and clinical judgment. In cases involving ionizing radiation, such as X-rays and CT scans, opportunistic imaging may result in additional imaging, which can contribute to increased cumulative radiation exposure for patients.

Referring providers may resist opportunistic imaging efforts due to the prospect of increased workload related to additional patient followup, documentation, workup, treatment initiation or modification, and uncertainty regarding unsuspected findings. Thoughtful implementation and clear reporting of findings are crucial to address these challenges and ensure that patients and referring providers understand the clinical importance and implications of otherwise unsuspected findings.

Lee says that despite numerous AI tools developed for opportunistic imaging, there is a need for reproducible, standardized, and generalizable tools across vendors, scanner models, and technical differences in image acquisition. Large-scale normative data across diverse populations is essential for body composition-based opportunistic imaging. Commercial availability of reliable, validated AI tools is necessary for routine clinical use.

To overcome existing regulatory and reimbursement obstacles, continued efforts are required to demonstrate clinical efficacy, improved individual and public health outcomes, cost-effectiveness, and cost savings in opportunistic imaging. Lee says measurable improvements in population health outcomes and systemlevel cost reduction through disease prevention and risk mitigation are appealing to payers and health care systems as the transition from volume to value-based models continues.

Technological Advances and Integration
Continuous advancements in imaging technologies, such as advanced MRI techniques and molecular imaging, contribute to the precision and relevance of opportunistic imaging. In addition, the integration of AI technologies holds promise for enhancing accuracy and efficiency. AI algorithms can aid health care professionals in analyzing large datasets, facilitating the identification and interpretation of incidental findings.

iCAD and Medimaps have made significant strides in utilizing AI resources in opportunistic imaging. Both companies demonstrate the potential of AI-driven tools in opportunistic imaging, showcasing innovations that could revolutionize health care by providing valuable insights beyond traditional applications.

iCAD, approved for deep learning AI in 2017, has FDA-cleared solutions for cancer detection and density assessment. The ProFound Risk solution is currently under review by the FDA and may be used for investigational purposes. The ProFound Breast Health Suite, powered by AI innovations, provides a comprehensive approach to cancer detection, density assessment, and personalized risk evaluation, demonstrating excellent clinical performance. iCAD is also set to launch ProFound Heart Health, aiming to identify and measure breast arterial calcifications from mammograms, providing insights into a patient’s risk of heart disease.

The ProFound Breast Health Suite is designed for detection, density assessment, and risk evaluation. Jonathan Go, chief technology officer of iCAD, says it not only exhibits up to double the clinical performance in cancer detection compared with alternative AI platforms but also effectively minimizes false positive results. Simultaneously, it precisely evaluates breast density and cancer risk. ProFound Detection scores cases and lesions to assist health care providers in identifying and prioritizing areas of concern. The Density Assessment solution streamlines and standardizes breast density reporting and stratification, providing accurate and reliable results. It analyzes 2D or 3D mammogram images, offering clinicians patientspecific breast density assessments.

The Risk solution offers up to 2.4 times more accuracy than traditional risk models, such as Tyrer-Cuzick and Gail. Personalized based on age and image evidence directly from mammograms, it provides a risk probability score for developing breast cancer in the next one or two years. Per Hall, MD, a professor/senior physician at Karolinska Institute, says models accurately predicting an individual woman’s risk of developing breast cancer mark a transition from age-based screening to risk-based screening. Research demonstrates the ability to more accurately stratify women based on short-term risk, opening avenues for new paradigms in breast cancer prevention and treatment.

iCAD will introduce ProFound Heart Health soon. Breast cancer and heart disease stand as the top two causes of death among women. Clinical findings indicate that calcifications in arterial vessels within the breast are associated with calcifications elsewhere in the body, prompting concerns about vascular or heart health. With the imminent launch of their Heart Health solution, iCAD aims to identify and measure the presence and extent of breast arterial calcifications. This will assist care teams in assessing a patient’s risk of heart disease directly from their mammogram. A study presented at RSNA 2023 highlighted the high accuracy of the AI algorithm in detecting breast arterial calcifications. The study revealed an age-related increase in the prevalence and distribution of breast arterial calcifications in a screening population. The prevalence rose from 4% in women under 50 years old to 40.8% in women aged 70 or older. The overall prevalence of breast arterial calcification detected by the AI algorithm was 14.8%.

Future Trends
Another area where opportunistic imaging shows potential is in screening for bone fragility and fracture risk. Medimaps’ ASXR is patented and undergoing development and optimization stages, though it has not yet reached commercial availability. ASXR addresses the significant challenge of undiagnosed osteoporosis with opportunistic bone fragility assessment solutions. It utilizes routine X-rays to identify at-risk individuals at an earlier stage than traditional methods allow. Early detection is crucial for initiating timely interventions that can enhance patient outcomes and alleviate the health care burden associated with osteoporotic fractures. Despite being in the developmental phase, Medimaps has made substantial progress in optimizing the algorithm, as evidenced by recent abstracts presented at conferences such as the European Congress of Radiology and the World Congress of Osteoporosis.

The development of ASXR follows a health advocacy model that underscores the significance of early detection and intervention. Medimaps is aware of the ethical considerations associated with opportunistic screening, including the risk of overdiagnosis, says Karen Hind, PhD, CCD, director of clinical affairs, research, and innovation. Overdiagnosis presents a critical challenge in opportunistic screening, potentially leading to unnecessary treatments and increased health care costs. Medimaps is ensuring their model minimizes the likelihood of false positives, thus avoiding unnecessary anxiety and interventions for patients.

Recognizing that many patients already undergo diagnostic imaging for various reasons, ASXR is designed to leverage existing images for assessing bone health without the need for additional procedures. This approach not only holds the promise of costeffectiveness but also expands the reach of bone health assessments to underserved populations, especially in settings where access to specialized diagnostic tools such as DXA machines may be limited. Hind believes Medimaps’ approach to opportunistic screening is poised to be a significant advancement in addressing bone health on a global scale.

The trajectory of opportunistic imaging involves the expanded utilization of existing AI tools across larger and more diverse patient cohorts, complemented by the development of comprehensive normative data. This evolution is likely to result in more individualized opportunistic imaging tailored to specific patient characteristics, contributing to the ongoing paradigm shift toward personalized medicine. The increasing prevalence of telemedicine is expected to impact the conduct of opportunistic imaging, with virtual consultations and remote imaging interpretation becoming standard practices. Furthermore, ongoing advancements in regulatory and ethical frameworks will continue to shape the future landscape of opportunistic imaging practices, ensuring responsible and patient-centered care.

Opportunistic imaging stands as a transformative approach in modernizing medical imaging, offering avenues for early detection, enhanced patient assessment, and cost-effective health care delivery. As technology progresses, ethical considerations are addressed, and regulatory frameworks adapt, opportunistic imaging is poised to assume an increasingly pivotal role in shaping the future of medical imaging and patient care. By embracing the potential benefits while navigating the associated challenges, health care providers can utilize opportunistic imaging to provide more thorough and personalized care for diverse patient populations.

— Rebecca Montz, EdD, MBA, CNMT, PET, RT(N)(CT), NMTCB RS, has worked at the Mayo Clinic Jacksonville and University of Texas MD Anderson Cancer Center in Houston as a nuclear medicine and PET technologist.