ABSTRACT
Objectives: 1. To recognize the impact of the COVID-19 pandemic to imaging in Nuclear Medicine. 2. Tounderst and the importance of the V/Q study during a pandemic and how to modify the study for the safety of patients and technologists while still providing quality images. 3. Understanding the benefits of perfusion SPECT/CTstudies compared to a traditional V/Q study. 4. To provide examples of both positive and negative studies forpulmonary embolism with SPECT/CT. Pulmonary embolism (PE) has been and continues to be a challengingdiagnosis especially in the new era of the COVID-19 global pandemic. Challenges of COVID-19 in Nuclear Medicineinclude contamination, spread of disease, availability of radiotracer, the long exam duration, reliance on patientcooperation, radiation exposure to patients/technologists and diagnostic certainty. In our institution, we followed theSNMMI guidelines of foregoing the ventilation component of a V/Q scan and relying on perfusion only imaging forPE diagnosis. Due to the caution of aerosol spread and difficult system contamination clearance, using Hybridperfusion Single-Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) imaging for PE is a comparable alternative to the traditional V/Q scan with multiple benefits. This can provide a possible solution tomany of the challenges of the current pandemic. SPECT/CT has demonstrated better certainty of identifyingperfusion defects compared to planar imaging alone. This essay will retrospectively compare a traditional V/Q scan with perfusion SPECT/CT imaging and evaluate radiation exposure, exam duration and COVID-19 exposure. Thetotal radiation exposure from the traditional V/Q scan is 2.575 mSv compared to 2.63 mSv from the SPECT/CTstudy. However, other aspects of the study had significantly improved with the SPECT/CT study including total examduration, technologist exposure time, reliance on patient cooperation, the need for a repeat ventilation and improvedaccuracy. The benefits of additional anatomical localization of perfusion defects, parenchymal disease and incidental findings are also an advantage that should not be overlooked. Illustrative cases will show both positive and negative perfusion studies for pulmonary emboli. We continue to accrue patients for further analysis.
ABSTRACT
Objectives: Nuclear medicine technologists experience various exposures throughout a typical workday. However, the introduction of Covid-19 to the work environment has produced a new hazard that needs to be addressed.Occupational exposure is currently limited to 50 mSv per year according to the Nuclear Regulatory Commission(NRC) which can be received from a source or machine. Conversely, there is no limit on COVID-19 exposure and the guidelines on proper personal protective equipment (PPE) usage are continually being updated during thecurrent pandemic. One of the most common studies in Nuclear Medicine is the Ventilation/Perfusion (V/Q) Lungscan which also poses as one of the biggest exposure risks to nuclear medicine technologists regarding bothradiation and COVID-19. Patient cooperation is key to a proper ventilation study. If the patient is unable to tolerate the mask or there is not a sufficient seal on the mask, the leaking radiotracer not only adds to the technologist'sradiation burden but also COVID-19 exposure. In addition, the contamination of the Xenon delivery system has prompted new SNMMI guidelines during the pandemic to forego the ventilation portion of the exam. At ourinstitution, the ventilation portion of the study is no longer performed during the pandemic and have switched toperfusion images with SPECT/CT as our new standard of care protocol. The purpose of the study is to review thisalternative lung study and compare imaging time, radiation and COVID-19 exposure. Methods: This retrospective study reviewed the current institutional imaging protocols and SNMMIrecommendations for V/Q studies. The imaging protocols were reviewed and measurements of the total imagingtime, radiation exposure and COVID-19 exposure were assessed. Perfusion SPECT protocol parameters are 15seconds a stop for 120 stops, acquiring on both heads. The CT portion has the low-dose screening chest CTprotocol. Results: The traditional standard protocol at our institution utilized 5 mCi of Tc-99m MAA for the perfusionportion of the study (2.035 mSv) and 20 mCi Xe-133 (0.54 mSv) for a total of 2.575 mSv. Taking advantage of thenew cameras and technology at our institution, we reduced the perfusion dose to 4 mCi of Tc-99m MAA for theperfusion portion of the study (1.63 mSv) and the low-dose CT adds 1.0 mSv for a total of 2.63 mSv. The totalimaging time is < 18 mins for the SPECT/CT and 30-60 mins for the traditional V/Q study. Conclusion: Eliminating the ventilation portion of the exam and performing SPECT/CT provides for a considerably faster exam time with comparable radiation exposure to the patient. Furthermore, it significantly reduces the radiation exposure to atechnologist by decreasing the time spent with the patients, is less reliant of patient cooperation and provides fortechnically better-quality studies. The additional major benefit is reducing the COVID-19 exposure to technologistsduring the pandemic.