Impact of Teleradiology on Oncological Interpretation of PET-CT Scans

Introduction

Cancer is a prime cause of death globally and accounted for about 10 million deaths in 2020. According to the World Health Organization, breast, lung, colorectal, and prostate cancers are the most prominent cancers. The World Cancer Research Fund International (2020) reported that 19.3 million new cancer cases (18.1 million excluding nonmelanoma skin cancer) were diagnosed worldwide in 2020 and expected that the cases will increase to approximately 29 million by 2040.[12] A report “Clinicopathological Profile of Cancers in India: A Report of Hospital Based Cancer Registries, 2021,” by the Indian Council of Medical Research (ICMR) under the National Cancer Registry Programme (NCRP), estimated 1.39 million new cancer patients in India.[3]

A rapid and accurate radiological interpretation of the imaging is essential for the early diagnosis, staging, and care of cancer patients. However, there is a critical scarcity of professional radiologists across the globe. Their limited availability, accessibility, stress, and burnout are the major obstacles in patient care and management. A White Paper by the European Society of Radiology (2022) affirms that burnout, due to severe work-related stress, is a global health problem and is prevalent among 47% of radiologists.[4] Moreover, according to a report by the Royal College of Radiologists, the present workforce issues were “unsustainable.” On the other hand, every month that cancer treatment is postponed due to a delay in diagnosis, mortality risk increased by almost 10%.[5] Teleradiology and teleoncology subsets of telemedicine can assist in removing these obstacles by offering specialized care across the gamut of clinical specializations, enhancing cancer-related health care for all patients regardless of their location.[6789] Teleradiology is the electronic exchange of diagnostic radiographic imaging studies for interpretation and/or consultation between two sites. Various clinical settings have attempted teleradiology, and the results show at least equality to in-person care and overall patient and health-care provider satisfaction.[10] Furthermore, the digitization of medical images in standard Digital Imaging and Communications in Medicine (DICOM) format and the seamless integration of imaging modalities through the Picture Archiving and Communication System (PACS) and Radiology Information System (RIS) has facilitated effortless and easy acquisition and transfer of images across networks globally from anywhere for viewing, interpreting, and reporting by radiologists utilizing the teleradiology platform.[11]

Positron emission tomography (PET)/computed tomography (CT) imaging is one of the valuable imaging tools for the diagnosis and staging of many malignant tumors, assessment of treatment plan and prognosis, and follow-up of cancer patients posttherapy.[1213] It is an effective and precise noninvasive imaging technique for tracking down the locations of nodal and distant metastasis, which in turn may guide treatment conceptualization, planning, delivery, and surveillance of high-precision radiotherapy.[14]

In a PET scan, a radioactive tracer such as 18F-fluorodeoxyglucose is administered through veins, inhaled, or swallowed depending upon the type of organ imaging. For distribution and uptake of radiotracer, the patient is allowed to rest quietly for 60–90 min in a shielded room. Then, imaging is performed on an integrated PET/CT scanner. CT images for attenuation correction and anatomic localization ensuing PET images of the concerned body part are obtained. ¹⁸F-labeled fluoro-2-deoxyglucose (¹⁸F-FDG), a glucose analog, is the most frequently used tracer. It enters the cells through glucose transporters such as GLUT1-13 and is converted to (¹⁸F) FDG-6-phosphate. As compared to the healthy tissues, the tumors express excessive glucose transporters and have an increased rate of glucose metabolism, thus taking up glucose with great avidity. The phosphorylated (¹⁸F) FDG cannot be further metabolized and gets trapped in the cell. The radioactive decay of fluorine-18 of FDG would make the sites of active malignant tumor appear as hot spots or foci of hypermetabolism.[15161718] PET/CT is a hybrid imaging, where both morphological and functional characteristics have been utilized for the staging of cancers.[1920] Pretherapeutic staging of the whole body can be done in a single study.[21] The utilization of PET-CT in interpretations of cancers has been well documented.[1314162223] However, interpreting PET-CT images requires specialized training and expertise, and not all medical facilities have access to a radiologist with the necessary skills. This is where teleradiology comes in, enabling remote interpretation of scans by a qualified radiologist.[24]

The use of teleradiology with integration of experienced radiologists, providing expert advice and interpretation, may yield good results for cancer detection and treatment planning. The aim of the present study was to assess the role of teleradiology in the oncological interpretation of PET-CT scans. This article reviews teleradiology practice by US board-certified radiologists who undergo approximately 3–4 months of training in nuclear medicine during the course of diagnostic radiology residency. In contrast to the US, the training for nuclear medicine physicians in India is for a minimum period of 2 years. There is undoubtedly a huge need for nuclear medicine physicians or nuclear radiologists for reporting FDG PET/CT for cancer care in India. In this scenario, teleradiology or telenuclear medicine is the need of the hour for quick throughput of reporting for various indications of oncology care.

Materials and Methods

A retrospective study was carried out between January 2018 and January 2023 and involved analysis of PET-CT imaging studies originating from different hospitals in India, the US, and Nepal by a teleradiology service provider headquartered in Bangalore, India. The DICOM images of the PET-CT scans of the suspected cancer patients were transmitted to the telereporting workflow platform “RADspa,” a cloud-based RIS/Picture Archiving and Communication System (PACS) over a high-speed internet connection. Board-certified radiologists impaneled with teleradiology service providers interpreted the scans and the reports were transmitted back to the hospitals over the same workflow platform. Other information such as patient prior images and reports and patient clinical and surgical history records were also uploaded into the RIS so that they were available to the radiologists along with the images. The PET-CT scans were evaluated for the diagnosis of malignant tumors, initial assessment and staging of recently diagnosed primary neoplasia, and follow-up of cancer patients to assess the therapeutic response or for detection of recurrence which would help the physician in the hospital in patient care and management. Wherever required, telephonic consultation between the interpreting radiologist and oncologist was enabled.

Results

In this retrospective study approved by our institutional review board, for 5 years, starting from January 2018, a total of 1137 PET-CT scans of a cohort of 1057 patients from different hospitals in India, the US, and Nepal were uploaded to the RADspa cloud server and interpreted by board-certified radiologists impaneled by teleradiology service provider [Figure 1].

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Figure 1 Geographical distribution of positron emission tomography–computed tomography cases interpreted by radiologists impaneled by teleradiology solutions

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The information about the demographics such as gender and age of the patients were also loaded into the cloud-based server [Table 1]. The patients (635 males and 422 females) ranged in age between 2 and 95 years with a mean age of 47.08 years 95% confidence interval (CI) (45.88–48.28) years. The maximum number of patients in the study belonged to the age group of 41–60 years.

The PET-CT images were taken with the patient in a supine position on the whole body from the skull base down to the mid-thighs or toes. The image count for the patients ranged from 138 to 7164 with a mean image count of 2292.87 [Figure 2]. Seven hundred and six cases had a count within the range of 2001–3000 images.

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Figure 2 Breakdown of positron emission tomography–computed tomography image counts for the patients

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The teleradiology services were provided to evaluate the PET-CT images of the patients with a clinical history of lymphoma, carcinoma, sarcoma, melanoma, myeloma, or having nodules or lesions in the body [Figure 3]. Out of a total of 1137 scans, 557 PET scans were performed to diagnose for unknown primary, whereas 580 scans were performed for surveillance following therapy [Table 2]. Two hundred and eighteen scans were positive for recurrence of cancer. 66.55% of 580 scans were performed for surveillance and to check for response to therapy. Fifty-five percent of total scans for response to therapy were positive responders, whereas 45% were negative responders. 33.5% scans of total scans were performed postchemotherapy while 3.34% of scans after the combination of chemo- and radiotherapy. There are heterogeneous systems for the staging of cancers that have been used while reporting these PET-CT cases. Hence, the cases were broadly categorized into five stages of cancer, 13.1% of cases were at Stage 0, 7.14% in Stage 1, 8.92% at Stage 2, 17.58% at Stage 3, and 38.7% at Stage 4.

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Figure 3 Breakdown of cases having a clinical history of cancers

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The maximum standardized uptake value is considered by nuclear medicine professionals and radiologists for measuring the uptake of FDG by malignant tissue and to distinguish between “normal” and “abnormal” levels of uptake.[2526] In our study, we were able to evaluate the intensity of FDG uptake ranged from moderate to very intense.

Turnaround time (TAT) is the amount of time between receiving the images on the telereporting platform and sending or verbally communicating the report to the doctors at the hospital. The mean TAT for reporting all PET-CT scans under the study was 20.06 h 95% confidence interval (19.35-20.78) [Table 3].

Discussion

Implementation and development of teleradiology and teleoncology services are specifically justified by the anticipated scarcity of radiologists and oncologists globally, the aging of the population, and the well-noted geographic discrepancy between the oncology health care and radiology workforce and population.[27] By 2033, the United States is expected to have a deficit of 17,000–42,000 radiologists, pathologists, and psychiatrists, according to the Association of American Medical Colleges. There is a ratio of approximately 1 radiologist for 100,000 population in India as compared with 1 for 10,000 in the United States while 20,500 radiologists for a population of 1.4 billion in India and 27 oncologists per 10,000 cancer patients worldwide.[924]

In our 5-year study from 2018 to 2023, the teleradiology services were provided to interpret a total of 1137 (PET-CT) scans of a cohort of 1057 patients, out of which 60.08% were males and 39.92% were females. The maximum number of patients belonged to the age group of 41–60 years. Similar results are interpreted in a report based on the study conducted under the NCRP launched by ICMR where 52.9% were males and 47.1% were females.[3] The age group of 45–64 years reported the highest proportion of cancer from all sites except for prostate cancer (over 65 years).[14]

The mean TAT for reporting of all PET-CT studies was 20.06 h 95% confidence interval (19.35-20.78), which means that the patients can consult the referring physician the next day and immediately plan for treatment. The early-stage diagnosis of cancer before it has progressed or metastasized is crucial for the immediate treatment conceptualization and plan and improves prognosis for the long-term survival of the patient. Thus, teleradiology is an invaluable tool in the field of oncology, providing rapid and accurate interpretation of PET-CT images, reducing health-care costs, and facilitating collaboration between medical professionals.

Conclusion

With its primary role to balance the skewed demand for and supply of radiology diagnostic services, teleradiology services ameliorate the shortage of expert radiologists, obviating the delay in the early diagnosis of cancer before it has progressed and thus enhance outcomes of cancer patient care solutions, treatment plan, and prognosis. The telehealth model proposed in the study would enable immediate access to radiologist reports for a population in need of rapid diagnosis. By ensuring early reporting of scans and therefore prompt institution of appropriate therapy, teleradiology can help to improve outcomes and thereby lower health-care expenses. In conclusion, teleradiology has the potential to be a game changer in cancer care.