Uptake: Growth of Fusion Imaging

September 15, 2023

By Madeline Greth, M
S, CNMT, RT(CT), PET, NCT—Program Director, Pennsylvania College of Health Sciences

Since the introduction of SPECT/CT two decades ago, it has rapidly grown and changed in clinical applications. What started as being solely for attenuation purposes now provides dual-modality simultaneous diagnostic imaging (1). This development has led to nuclear medicine and molecular imaging becoming intertwined with CT, thus requiring that technologist education provide a strong background in CT as well. With this change, avenues for dual certification should be made more accessible to benefit technologists and hospital systems alike.

The addition of CT to PET and SPECT has shown applications in all aspects of nuclear medicine and molecular imaging. The use of SPECT/CT in cardiology has led to improvements in diagnostic accuracy that allow reading physicians to more confidently assess images. The CT portion also allows for calcium scoring to be performed in conjunction with SPECT imaging, potentially providing insight into subclinical coronary artery disease (2). In general nuclear medicine and molecular imaging, SPECT/CT has improved localization and differentiation for studies such as 131I thyroid cancer imaging, parathyroid imaging, neuroendocrine tumors, lung nodules, brain tumors, bone metastases, and infection (3). SPECT/CT is also being utilized for lung scans that evaluate for pulmonary embolism. This use became crucial during the COVID-19 pandemic, when ventilation scanning was not routinely being done.

The incorporation of CT into PET scanners had a huge impact on oncology imaging. In 2001, only 2% of PET scanners were fused with a CT component; in 2018, that number rose to 96%, with the remaining 4% being either standalone PET or PET/MRI (4). The clinical PET scan volume has been growing steadily at 6% per year since 2013 (4). This growth is due not only to a PET scanner’s increased ability to detect function on a cellular level but also to the fact that the PET images can be fused with CT images for attenuation and localization.

The incorporation and still-growing applications of CT show that nuclear medicine technologists need a comprehensive knowledge base for CT as well as for nuclear medicine and molecular imaging. Some states—such as West Virginia, Rhode Island, New Jersey, Louisiana, Delaware, and Maine—acknowledge this need and require additional licensure for technologists to perform fusion imaging. Other states do not require specific licensure but do require additional training (5). Certifications can be acquired from certification boards such as the Nuclear Medicine Technology Certification Board (NMTCB) and the American Registry of Radiologic Technologists (ARRT).

Since its inception, the NMTCB’s CT examination has been a diagnostic CT credential geared toward testing a candidate’s knowledge and competency in the role of a computed tomography technologist. However, the eligibility requirements for NMTCB’s computed tomography examination were recently updated to ensure exam candidates are obtaining the appropriate experience and clinical competencies to ensure that they are suitably prepared for this post-primary examination.

The current NMTCB clinical guidelines require a minimum of 300 clinical hours spent performing at least 10 different CT procedures, for a total of 50 repetitions (6). The procedures may be performed on a stand-alone CT, a PET/CT scanner, or a SPECT/CT scanner. One of the reasons the NMTCB updated the CT exam eligibility requirements was to help address barriers that made it difficult for nuclear medicine technologists to operate CT scanners in any form.

ARRT CT certification requires completion of 16 hours of structured education meeting ARRT’s criteria. ARRT’s clinical experience requirements specify the CT procedures that must be performed and the number of repetitions of these procedures that must be documented.

Given the importance of CT in nuclear medicine imaging, the nuclear medicine community should be investigating better pathways for technologists to gain CT certification. One of the ways this could be achieved is through programs offering dual training in their curricula. Programmatically accredited programs already offer didactic CT education, but incorporating CT clinical hours as well will allow students to graduate with the capacity for dual certifications.

Multimodality certifications are beneficial not only for the technologist and the nuclear medicine department but also for the hospital. Employing technologists who are certified in multiple modalities gives a hospital flexibility to move staff where they are most needed. The COVID-19 pandemic has created new struggles for health care settings that are desperate for workers (7). Being able to shift employees between departments to meet critical need could be the difference between seeing patients or diverting them to a different facility.

Fusion imaging and the need for multimodality certification will only continue to grow. The benefits to the technologist, the department, the patient, the hospital, and the field of nuclear medicine are great. As a nuclear medicine community, we should encourage updates and upgrades to our education programs to reflect these changes and prepare our students for the future of nuclear medicine and molecular imaging.



  1. Hutton BF. The origins of SPECT and SPECT/CT. Eur J Nucl Med Mol Imaging. 2014;41:3–16.
  2. Abbott BG, Case JA, Dorbala S, et al. Contemporary cardiac SPECT imaging-innovations and best practices: an information statement from the American Society of Nuclear Cardiology. J Nucl Cardiol. 2018;25:1847–1860.
  3. Mariani G, Bruselli L, Kuwert T, et al. A review on the clinical uses of SPECT/CT. Eur J Nucl Med Mol Imaging. 2010;37:1959–1985.
  4. Young L. IMV: PET/CT drives PET scan volume to new heights. AuntMinnie.com website. https://www.auntminnie.com/index.aspx?sec=sup&sub=mol&pag=dis&ItemID=125533. Published May 20, 2019. Accessed January 25, 2023.
  5. Nuclear medicine technologist requirements by jurisdiction. Society of Nuclear Medicine and Molecular Imaging website. www.snmmi.org/IssuesAdvocacy/content.aspx?ItemNumber=5719. Accessed January 25, 2023.
  6. Computed tomography exam information. Nuclear Medicine Technology Certification Board website. www.nmtcb.org/exams/computed-tomography. Accessed January 25, 2023.
  7. Romero L, Bhatt J. Pandemic has made shortage of health care workers even worse, say experts. ABC News website. https://abcnews.go.com/US/pandemic-made-shortage-health-care-workers-wors%20e-experts/story?id=77811713. Published May 21, 2021. Accessed January 25, 2023.