Nuclear Medicine Clinical Practice in the United States During the COVID-19 Era and Beyond

Hand Cleaning

Before interacting with patients, the NMT must always perform hand hygiene (18). The most effective way to clean hands is with soap and water. Hand hygiene with alcohol-based hand rubs (60%–95% purity) works well if hands are not visibly soiled; regular washing at the sink is required if they are. Hygiene supplies including hand rubs, antimicrobial soap, paper towels, waste bins, and the like should be readily available in all locations that are adjacent to or involve patient care. NMTs should keep in mind the locations of sinks for situations that necessitate soap and water washing in place of hand rubs and make personal plans as to how and when they will use them (10). It can be expected that hand hygiene will need to be performed by each worker between 3 and 30 times per hour in a patient care setting to protect self and patient (19). Also, important to consider is the frequency of movement between imaging equipment, the patient, and the surfaces touched by human hands in the control room or desk areas around the imaging room. The many “hand touches” during nuclear medicine procedures presents many opportunities for hand hygiene.

Glove Use

NMTs entering patient care areas should do so with gloved hands (2,16). Hands should be cleaned before putting on fresh gloves to avoid transfer of organisms. Gloves that are put on unwashed hands are considered contaminated. NMTs should expect to change gloves frequently, both before and after many types of patient care duties. The WHO campaign My Five Moments of Hand Hygiene specifies types of patient interactions that require hand cleaning and glove change including before and after touching a patient, handling bodily fluids, and touching patient surroundings (20).

Face Coverings

Currently, the CDC recommends that all health-care workers including NMTs cover the face with PPEs such as respirators and face masks (21). Cloth face coverings worn by the general public are not considered protective for those who work with patients, particularly those who have known or potential COVID-19 infections. Goggles or face masks should be considered to protect the eyes as well. Personal eyeglasses are not substitutes when eye protection is needed. Ventilation lung scans are aerosol-generating procedures and require wearing masks with higher protection capabilities such as N95 masks as well as full face shields (16).

Isolation Gowns

NMTs should wear isolation gowns when entering patient care areas (15). This includes nuclear medicine imaging rooms. With the high potential for SARS-CoV-2 spread, NMTs assigned to perform aerosol-generating procedures such as ventilation lung scans must be given priority when gowns are in short supply (21).

Donning and Doffing Practices for Isolation Gear (Figs. 1 and 2)

Before the COVID-19 pandemic, most NMTs put little thought into changing gloves except when contaminated with radioactivity or visibly soiled, and minimal consideration to proper use of items such as isolation gowns. Donning (putting on) isolation gear should be done in a manner that prevents self-contamination and maintains hygienic standards (15). Before donning, hand hygiene must be performed and plans should be devised based on which items will be laid out for use. The general order for putting on isolation gear starts with donning the isolation gown and is followed by putting on a mask or respirator, eye protection, and finally gloves (15). The NMT should also understand when PPE items will need to be exchanged, and where and how items will be disposed of when finished.

• Download figure
• Open in new tab
• Download powerpoint

FIGURE 1.

CDC sequence for putting on personal protective equipment (PPE). (Centers for Disease Control and Prevention; March 14, 2020. https://www.cdc.gov/hai/pdfs/ppe/ppe-sequence.pdf.)

• Download figure
• Open in new tab
• Download powerpoint

FIGURE 2.

CDC sequence for safely removing personal protective equipment (PPE). (Centers for Disease Control and Prevention; March 14, 2020. https://www.cdc.gov/hai/pdfs/ppe/ppe-sequence.pdf.)

Doffing refers to removing gear when finished with patient care or a procedure (15). This should be done after the patient has been escorted away from the imaging room and before the NMT exits the room. The order for doffing includes first removing gloves because they are assumed to be contaminated, removing eyewear, and removing the isolation gown. If the hands become contaminated while doffing isolation gear, it will be necessary to perform hand cleaning. All contaminated items should be disposed of in an institution-approved waste bin. The face mask or respirator should be left on until after exiting the room.

Patient Scheduling, Registration, Arrival, and Discharge

In nuclear medicine departments, high throughput of procedures presents high risk for viral exposure and transmission. Prior scheduling practices often neglected to account for the infection prevention aspects of examinations, and during workdays NMTs routinely encountered subsequent patients before completing room cleaning, donning personal protection, or assessing the patient’s situation. In post–COVID-19 times, changes in examination scheduling must be made to widen time slots to allow NMTs to perform these duties (12). Longer time slots and avoiding overbooking of examinations will also limit patient contact with others in waiting areas and ensure availability of adequate nuclear medicine personnel to attend to patients.

In addition, in order to provide adequate social distancing in waiting rooms, nuclear medicine patients must not bring additional family members to appointments. Social distancing has required most institutions to reduce the capacity of their waiting rooms, and as such it may not be possible to for patients to arrive to their nuclear medicine appointments early. Many institutions are asking patients who arrive early to their appointments to wait in their cars until their appointment times; oftentimes a “virtual check-in” is used. The nuclear medicine department is notified that the patient has arrived and can thereby notify the patient when to come into the department. Because of these expanded appointment slots, this may require nuclear medicine departments to extend their clinic hours into the evening or into the weekend as well.

The registration process can increase time patients spend in close proximity to others in waiting rooms (12). Registration desks must be widely spaced with shields to ensure distance between admitting clerks and patients. Masks, hand-cleaning supplies, and instructions must be provided in waiting rooms also for patients and visitors. In addition, waiting room furniture and surfaces should be cleaned as necessary to ensure that any potential COVID-19 virus is removed. Visual measures that reinforce patient safety such as cleaning monitors and pens should be performed between each patient admission. This may require additional ancillary staff to monitor and clean waiting rooms. With heightened infection prevention needs, NMTs need to devote additional time for planning, setup, and donning personal protection before starting examinations as part of each examination workflow. Extra time is required also to ensure that each patient has sufficient PPE and assessment of symptoms. Neglecting any of these duties puts staff, patients, and visitors at risk for infection.

On arrival in the nuclear medicine department, inpatients with confirmed COVID-19 disease or patients under investigation (PUI) should be given masks to wear if that has not already been done (12). When a COVID-19 patient arrives at the department, they should be escorted directly to the imaging/procedure room and not stop in the waiting room or hallways. The NMT should be prepared with PPE before the arrival of the patient including an N95 mask, goggles or face shield, and isolation gown. In addition, some institutions may require head or shoe coverings. Donning and doffing procedures must be adhered to as described previously to ensure there is no possibility for contamination (15). The registration process can increase the time patients spend in close proximity to others in waiting rooms. To reduce the patient time in the department, there should be careful coordination of escort services to quickly return inpatients to their wards. In addition, the NMT should have all doses, flushes, and the ventilation aerosol unit or other equipment staged in the designated imaging room before the patient arrives.

After the procedure is completed and the patient has left the room, it should be closed to allow any residual particles to be cleared by the air system. In general, this would require 6–12 complete air exchanges (4). This process usually takes over an hour depending on air flow rates and building engineering requirements. After this time housekeeping should be called in to perform terminal cleaning (deep cleaning—as done with tuberculosis patients in many institutions). Once housekeeping has cleared the room, the technologist should thoroughly disinfect and wipe down the camera, camera collimators, imaging bed, hand controller, and computers. Housekeeping in general will not clean technical equipment. When cleaning is completed, the room can safety be put back into routine use. The process to turn over the imaging/procedure room after scanning SARS-CoV-2–positive patients will add at least 90 min to any nuclear medicine study and this additional time will have to be accounted for in the clinical schedule.

Resource Allocation

Risk due to lack of human resources and ability to use sick time are legitimate concerns in nuclear medicine departments. Common complaints among NMTs are that there is a short supply of contingency staff available to fill in for absences due to budget decisions and technologist shortages. It is crucial that management devote sufficient resources to a float pool of NMTs to cover absences, and not punish those who need to be absent for personal illness or caring for sick family members. As mentioned above, escort services and registration staff are essential to safe department functions. Greater numbers of support staff need to be included in budgets.

Allocation of resources pertains also to PPE supplies. Media reports have brought up serious PPE shortages for nurses and physicians. However, NMTs encounter situations of risk comparable to nurses and physicians but are less visible to management. NMTs have sufficient reason to claim adequate supplies of items such as respirators, isolation gowns, gloves, and shoe protectors and should be given equitable access. Some state health regulations require that priority for PPE be given to workers with a likelihood of contact with infected persons, workers who have risk of spreading infections to vulnerable persons, and workers who need to perform aerosol-generating procedures (21). NMTs fit these criteria precisely in hospital settings, as noted with the risk of aerosolized particles exposure during lung ventilation studies (16). However, the procurement of PPE may be challenging as other areas in the facility (ICU, emergency room, surgery) are also competing for these limited resources. It is important that nuclear medicine management highlight that staff are dealing with the potential of “droplet contamination” during the performance of lung ventilation studies and MPI stress procedures. It is necessary to educate those responsible for supply chain management to the urgent need for PPE for nuclear medicine. In addition, NMTs should also be tested for COVID-19 virus based on individual institution policies.

Further, the CDC (24) states that health-care organizations should develop contingency plans for extra PPE supplies for ensuring operational safety for all in case of PPE shortages. Specific protocols should be developed to address the real needs of individual nuclear medicine departments. Nuclear medicine managers must consider usage rates to plan for daily patient loads and surge capacity. Surge capacity describes the need for additional PPE supplies during an outbreak or pandemic situation. The PPE supply stock should be based on the volume of nuclear medicine procedures (including after hours and on-call studies) that are able to be performed given the limitations due to COVID-19 restrictions. For example, a routine lung V/Q, which normally required 1 h to complete, now with COVID-19 requirements may take up to 3 h.

Patient Preparation

As stated previously, patients who are SARS-CoV-2–positive or PUI should be brought to the nuclear medicine department with an appropriate face mask. The NMT performing the examination should have had sufficient time and opportunity for planning, preparation, and examination setup. All efforts should be made to complete the examination efficiently and minimize time the patient must spend in the department. Infection prevention measures should be adhered to thoroughly as described above.

Lung V/Q Imaging

Early on in nuclear medicine practice, lung V/Q imaging was described as one of the most commonly performed studies (26). V/Q scans have declined in frequency as other diagnostic methods, notably the CT pulmonary angiogram, have become more popular. With the advent of SPECT and SPECT/CT, V/Q scanning has been significantly improved with a higher sensitivity and specificity compared with planar V/Q scanning (27). Nuclear medicine lung scans have continued to have a role in diagnosing pulmonary embolism (PE) and assessing other causes of chest pain and dyspnea. During the COVID-19 pandemic, it has been suggested by Zuckier et al. (28) that a shift to a diagnostic algorithm can reduce the number of required ventilation studies. However, this algorithm still identifies a population of patients who should go on to complete a V/Q scan with aerosol precautions.

The ventilation procedure can be performed with numerous agents including ¹³³Xe, ^99mTc-diethylenetriaminepentaacetic acid (DTPA), ^81mKr, or ^99mTc-microparticles (^99mTc-Technegas; Cyclomedica) (29). Of these ventilation imaging agents, ^81mKr and ^99mTc-Technegas are not readily available in the United States. However, Cyclopharm Limited filed a 505(b) New Drug Application for Technegas with the U.S. Food and Drug Administration on March 30, 2020 (30). Before COVID-19, ongoing clinical trials were active in the United States, which may make Technegas available in the next year in the United States.

Aerosolized procedures for lung scanning as with ^99mTc-DTPA present the highest risk for COVID-19 exposure to NMTs. The technologist must be in the room with the patient assisting during the ventilation procedure. In order to get an adequate count rate, the patient must inhale on the ventilation system for at least 1.5 to 3 min. During this time, it is not uncommon to have some aerosolized particles escape from the patient’s mouthpiece into the surrounding area and deposit contamination on the NMT and in the room environment. These particles are now understood to have potential COVID-19 virus and, as such, are a hazard to technologists.

The noble gases, ¹³³Xe and ^81mKr, for lung ventilation carry a smaller risk of exposure to COVID-19 for 2 reasons. Use of these gases requires the imaging room to have negative pressure, and the amount of time the patient has to be ventilated is usually less than a minute. Both of these factors will reduce the possibility of COVID-19 exposure to NMTs.

Finally, Technegas is certainly a promising agent that has been used extensively in Europe and Australia. This system uses an ultra-fine microaerosol, of graphite, called “bucky balls” (31). These bucky balls are delivered to the patient via a Technegas generator. TcO4⁻ is placed into an alcohol-moistened graphite crucible, which is heated to produce the bucky balls coated with ^99mTc. The patient inhales via an attached breathing apparatus 2 or 3 times to get approximately 1.0 mCi (37 MBq) into their lungs. Because only 2 or 3 puffs are necessary to get adequate images, this system greatly reduces potential COVID-19 exposure to technologist.

Regardless of the ventilation agent, every effort must be made to mitigate the risk of COVID-19 exposure with lung ventilation procedures. All patients who are to have lung ventilation imaging should have a COVID-19 test. For inpatients, COVID-19 testing is now a common procedure, but for outpatients this is more challenging. Patients who are having lung ventilation studies must have a COVID-19 test before their lung V/Q scan. This order will need to be placed by a nuclear medicine provider (2). At the present time, most facilities have initiated outpatient drive-up COVID-19 testing as a preprocedure requirement for aerosol-generating procedures. These testing centers are normally only open Monday through Friday. COVID-19 testing results normally take 1−2 d to be returned. As such, outpatient lung scans may have to be scheduled later in the work week to allow time for the patient to go to a testing center for the drive-up COVID-19 test and then to get the results back before the lung V/Q scan. In addition, patients should self-isolate between their COVID-19 test and their lung V/Q scan to reduce the chance of further COVID-19 exposure.

Once results are received, negative COVID-19 patients may proceed with their lung V/Q scan. Positive COVID-19 patients need to be referred to their primary care providers for management. Most facilities have a mechanism in place through their infection control service to trigger the appropriate notification of primary care physicians when a patient has a positive COVID-19 test. However, because the COVID-19 test was originally ordered by a nuclear medicine provider at the time the lung V/Q scan was scheduled, a policy must be put in place for the nuclear medicine service to ensure that primary care providers are notified of the positive COVID-19 test and determine whether the lung V/Q scan can be delayed until the patient is COVID-19–negative. Institutional policies will differ and are continually changing during this pandemic as new data becomes available, but minimally the nuclear medicine department must document that the patient’s primary care physician was notified of the positive test and is agreeable to delaying or rescheduling the lung V/Q scan.

Another challenge that is being recognized with this pandemic for nuclear medicine departments is that scans are requested of patients who have previously been COVID-19–positive. Again, institutional policy will differ but in general the CDC recommendation is that a COVID-19 patient should have negative results of a Food and Drug Administration Emergency Use Authorized COVID-19 molecular assay for detection of SARS-CoV-2 RNA from at least 2 consecutive respiratory specimens collected ≥24 h apart (total of 2 negative specimens) (2).^. However, if a patient must be ventilated who is known to have COVID-19 or is a PUI, as in emergency cases, every precaution should be taken to ensure that there is no cross-contamination. NMTs can use the following principles of time, distance, and shielding for protection from COVID-19 exposure during ventilation scans: Time—the least amount of time with the patient the better. The number of people who come in contact with the patient should be limited, such that preferably only 1 technologist performs the scan; distance—the further away from the patient the technologist can be, the better. It has been noted that COVID-19 particles can travel up to 6 ft; shielding—the “barrier” is PPE and negative pressure rooms rather than lead. If possible, the patient should be ventilated in a room with negative pressure. If there are not rooms with negative pressure, then a room with a single camera that can be closed off after the procedure should be used.

Myocardial Perfusion Imaging (MPI)

MPI is a well-validated, noninvasive method to assist with the determination of diagnostic and prognostic information for patients with suspected or known coronary artery disease. Images are obtained during rest and then during myocardial hyperemia, induced by exercise or pharmacologic stress agent. Rest and stress images are compared to determine the coronary flow reserve and identify areas of compromised myocardial perfusion. Stress testing puts the technologist in close proximity with the patient for a prolonged period of time. The preferred method for inducing hyperemia is exercise, but pharmacologic stress is performed in more than 50% of patients (32,33). Most pharmacologic stress MPI studies are performed with the vasodilators adenosine, dipyridamole, or regadenoson. Making use of vasodilators, particularly regadenoson, rather than treadmill stress tests shortens procedure time and reduces equipment contamination and exposure to NMTs, leading to reduced risk of viral transmission (12). The side effects most often seen from these agents are mild and include flushing, chest pain, dyspnea, dizziness, and nausea. Should the nausea progress to vomiting, the NMT has added risk for COVID-19 exposure (33). The technologist is the primary caregiver for the patient and will need to perform additional cleaning measures.

The NMT should also make extra notes of cardiac arrhythmias, low ejection fraction, and myocarditis (12). These issues are reported to be correlated with some cases of COVID-19 and should be relayed to the supervising nuclear medicine physician or cardiologist.

Therapies and Hybrid Imaging

NMTs should keep in mind that cancer patients may have greater risk for contracting COVID-19, and for severe symptoms should they contract the disease (34). Susceptibility also depends on individual patients’ conditions and comorbidities. Assessment with the oncology team should be made to determine the need for urgency for a given patient’s therapeutic (and any related diagnostic) procedures. Procedures that are of lower value or are not urgent should be postponed until effects of the pandemic subside (35). However, asymptomatic patients undergoing PET/CT and SPECT/CT scans have been found to have COVID-19 from the chest CT results of these imaging scans (36). As such, NMTs must continue to use COVID-19 precautions to protect themselves and other from asymptotic carriers. Some patients, for example, those needing hyperthyroidism therapy, can often be managed temporarily with medication until an appropriate time for the radionuclide treatment can be arranged (12).

Postexamination Procedures

Thorough imaging room cleanup should occur after each patient leaves the imaging room. This includes disinfecting γ-camera gantries, imaging tables, computer keyboards and mouse, sphygmomanometer and blood pressure cuff, infusion pump, treadmill, chairs, and all surfaces that may have been touched by the patient or someone with potentially contaminated gloves (12). Terminal cleaning can be done by housekeeping staff according to policy, but ultimately NMTs are responsible for cleaning and handling imaging equipment and medical devices.