The Future of Continuing Education in Diagnostic Imaging

Infection Control for the Radiologic Technologist

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Author: Shaina McQuilkie, D.C.

Abstract: Imaging techniques are commonly used to confirm suspected cases of infectious diseases and are often used to visualize complications that may occur secondary to infectious pathogens. Registered technologists (R.T.) need to be aware of common concerns regarding infectious disease encountered in the radiology department. R.T.s need to be aware of the transmission modes of various infectious agents and the standard precautions that must be utilized to prevent the spread of infectious diseases. Furthermore, R.T.s should be aware of the radiographic procedures that are used for various infectious diseases and significant findings that are often visualized on examination of infected patients. This article provides a continuing education activity for registered technologists, with emphasis being placed on the following infectious diseases: Methicillin-Resistant Staphylococcus aureus (MRSA), Hepatitis, Clostridium difficile (C. diff) meningitis, tuberculosis (TB), Ebola, and measles.

 

Objective

 

This article was designed as a continuing education (CE) activity with focus placed on the topic of infection control. The participants will be able to identify common concerns, including signs and symptoms, of infectious agents (MRSA, hepatitis, C. diff, meningitis, TB, Ebola and measles), and how they relate to the R.T. Further, they will be able to identify the mode of transmission of various infectious diseases and describe standard precautions that should be utilized when working with patients with suspected infectious diseases to prevent the spread of disease. Lastly, participants will be able to identify specific radiographic procedures to be considered for each infectious disease and recognize significant findings that are visualized on examination. A technologist may benefit from an improved understanding of infectious disease, as it will help to prevent the spread of infection within the work center.

 

Introduction

 

Infectious diseases are becoming more prevalent in hospitals and can cause serious infections, some of which are potentially fatal. Contagious infectious diseases add a new dimension to the role of the radiology department [1]. Needle stick injuries, blood contact, airborne infections and any kind of contamination pose a risk for all healthcare workers. The risk of hospital infection has been increasing in the radiology department as the number of patients and the exposure time between patients and radiology workers have increased, especially with the use of new modalities over the last few decades [2].

 

The radiology department can play a pivotal role in infection control within the hospital setting, as it is a high traffic area that frequently encounters patients with highly contagious diseases and therefore has the potential to be a major source of infection transmission among in-patients and out-patients, health care personnel, and hospital visitors [3]. Radiology departments need to develop protocols for various modalities used in imaging patients with contagious, and possibly deadly, infections [1,3].

 

The principle goals of infection control for the radiology department should be to optimally observe infectious disease control precautions and adhere to the standards for environmental and equipment cleansing [3]. Infection control steps that are relevant to the radiology department, and in particular the R.T., include: exercising proper contact precautions, performing adequate environmental cleaning, and ensuring staff adhere to infection control policies through education and monitoring [3].

 

 

Methicillin-Resistant Staphylococcus aureus (MRSA)

 

Staphylococcus aureus (SA) bacteria are commonly found on the skin or in the nares of healthy people, with approximately 20-30% of the population showing either persistent or intermittent nasal colonization with this bacteria [3,4,5]. However, numerous other sites may be colonized, including the axillae, groin, and gastrointestinal tract [5]. Most SA infections are minor skin infections that do not require treatment with antibiotics; however, SA can also cause serious infections related to surgical wounds, bacteremia, and pneumonias [3]. MRSA isolates are resistant to all available penicillin’s (methicillin, oxacillin and cloxacillin), cephalosporins, monobactams, and carbapenems, which makes them difficult to treat effectively [3, 6]. Penicillins, cephalosporins, monobactams, and carbapenems are antibiotics that belong to a large class of antibiotics called β-lactam antibiotics. This group of antibiotics exhibit a variable range of microbial activity and have a wide range of clinical uses.

 

For decades, MRSA has been considered the prototype of multi-resistant nosocomial pathogens, causing infection in high-risk patients. However, changes to the healthcare system, combined with the evolution of this microorganism, have transformed MRSA into a cause of community-onset infections, in both patients who have come into contact with the healthcare system and patients that have not [7,8]. The frequency of MRSA infection continues to grow in the hospital and community settings in the United States and globally [8]. A growing concern is the emergence of MRSA infection in patients with no apparent risk factors [8].

 

Of particular concern for the R.T., MRSA can be transmitted from person to person and can survive on various surfaces, including X-ray cassettes [9] and MRI surfaces [10]. Further, research has found that various other surfaces in treatment rooms, including the computer keyboard, disposal glove dispenser, patient file and telephone, among other items, can be contaminated with this pathogen. Therefore these surfaces may serve as fomites for MRSA and need to be properly decontaminated after working with a patient infected with MRSA.

 

Transmission of Methicillin-Resistant Staphylococcus aureus (MRSA)

 

MRSA is spread through direct contact with an infected person or by indirect contact via a vector such as a healthcare worker, personal item or contaminated surface [2,11]. The major reservoir of MRSA in the hospital setting is infected or colonized patients, and occasionally healthcare workers. Improper hand washing is the most common mechanism of transfer responsible for healthcare worker transmission of MRSA [2].

 

Methicillin-Resistant Staphylococcus Aureus (MRSA) Radiology Specific Exams          

 

MRSA can infect various areas of the body, therefore physicians may order different modalities depending on the patient’s symptoms. For example, a chest x-ray may be ordered to check for pneumonia, while an ultrasound, CT or MRI may be ordered to visualize infected abscesses. Results of imaging procedures will vary among patients, depending on the area under investigation.

 

 

Hepatitis

 

Hepatitis is an inflammation of the liver, most commonly caused by a viral infection. There are five main hepatitis virus types – A, B, C, D and E [12,13]. Hepatitis A,B, and C are the most common types of hepatitis that R.T.s encounter.  Acute infection with hepatitis may occur with limited or no symptoms, or may include symptoms such as jaundice, darkened urine, extreme fatigue, nausea, vomiting and abdominal pain [12].

 

 

Jaundice Patient

Figure 1: A patient with jaundice. Courtesy James Heilman, MD (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons.


Hepatitis A infection typically causes no symptoms and goes unrecognized in many patients. However, acute hepatitis symptoms, as discussed above, can occur. Recovery from Hepatitis A is usually complete unless the infection is very severe (fulminant). However, these cases are very rare. People infected with Hepatitis A do not become carriers and the virus does not cause chronic hepatitis [13].

 

Hepatitis B infection is more serious than Hepatitis A and can be fatal in some cases, especially in the elderly [13,14]. The severity of the infection can range from mild to severe. Patients with Hepatitis B may have joint pain and itchy red hives on the skin [13]. Approximately 5 to 10% of infected adults will develop chronic hepatitis or become carriers. In children, the chance of developing chronic hepatitis is far greater – up to 90% of infected newborns and up to 50% of infected young children will develop the chronic disease. Hepatitis B is an important occupational hazard for health care workers performing procedures where there is a risk of exposure to various body fluids, including R.T.s [12,13].

 

Hepatitis C infection can cause both acute and chronic hepatitis infection, with chronic infections occurring in approximately 75% of patients [15]. The chronic infection is usually mild, however, about 20 to 30% of infected patients develop cirrhosis, and liver cancer can occur once cirrhosis has developed [15]. The most common modes of infection are unsafe injection practices, inadequate sterilization of medical equipment in healthcare settings, and unscreened blood and blood products [15]. Proper sterilization of all radiographic equipment used for examination of patients with Hepatitis C is essential to prevent the spread to subsequent patients.

 

Hepatitis D only occurs as a co-infection with Hepatitis B. This infection usually makes the hepatitis B infection more severe [15].  

 

Hepatitis E may cause severe symptoms, especially in pregnant women [15]. Hepatitis E is usually self-limiting, but it may develop into fulminant hepatitis [17]. However, this is rare, patients infected with Hepatitis E do not usually develop chronic disease and do not usually become carriers [15]. 

 

Transmission of Hepatitis

 

Hepatitis A is primarily transmitted via the fecal-oral route which occurs when an uninfected person ingests food or water that has been contaminated with the feces of an infected individual [14]. However, the virus may be spread through close physical contact with an infected individual [14].

 

Hepatitis B can survive outside the body for at least seven days [15]. The incubation period of the virus is 75 days, however, it can vary between 30 and 180 days. The virus can be detected in the body between 30 and 60 days after infection and can persist and develop into chronic hepatitis B [15]. Hepatitis B is most commonly spread through perinatal transmission or through horizontal infection in highly endemic areas. However, it is also spread by percutaneous or mucosal exposure to infected blood and various body fluids, as well as through saliva, menstrual, vaginal, and seminal fluids [15]. Sexual transmission may occur, and the re-use of needles and syringes either in hospital settings or among illicit drug users may also lead to infection with Hepatitis B [15]. Furthermore, infection can occur during medical, surgical, and dental procedures, tattooing or through the use of razors and similar objects that are contaminated with the virus [15]. However, many cases of hepatitis B have no known source [14].

 

Hepatitis C is a blood borne virus that is most commonly transmitted through the use of contaminated needles used in drug sharing, tattooing and body piercing [14,16]. Additionally, it can be transmitted in healthcare settings by the reuse or inadequate sterilization of medical equipment [16]. Hepatitis C can also be transmitted through sexual contact, from mother to child during birth and through transfusion of unscreened blood products; however, these causes are rare [16].

 

Hepatitis D is most commonly transmitted among people who share needles to inject illicit drugs [14].

 

Hepatitis E is mainly transmitted via the fecal-oral route due to fecal contamination of drinking water [17]. However, it can also be transmitted by foodborne transmission from the ingestion of food derived from infected animals, transfusion of infected blood products and transmission from mother to child [17].

 

Hepatitis Radiology Specific Exams

 

Ultrasound: abdominal

The findings will show hepatomegaly (the most sensitive sign) >15.5 cm at the midclavicular line [18]. Periportal edema, and gallbladder wall thickening is variably present (most often seen with hepatitis A) [18]. “Starry sky appearance” has been found to have poor specificity and sensitivity.

 

CT: abdomen

The findings show hepatomegaly > 15.5 cm at the midclavicular line. There may be decreased attenuation around the portal system and at the hepatic hilum [18]. Additionally, there may be diffusely decreased parenchymal attenuation on non-contrast CT that may be diffuse edematous change, hepatic statosis or the result of acute hepatitis. There may also be periportal/hepatoduodenal lymphadenopathy [18].

 

CT showing hepatomegaly
Figure 2. CT showing hepatomegaly. By Hg6996 (Own work) [Public domain], via Wikimedia Commons.

 

MRI (used in rare cases)

Findings on MRI are nonspecific; this modality is often used to exclude other causes of a serum liver function test disorder [18].

 

 

Clostridium Difficile (C.Diff)

 

C. Diff is the leading cause of hospital-acquired diarrhea in Europe and North America and is a serious re-emerging pathogen [19]. During the last two decades, the incidence and mortality rate of C. Diff infection has increased remarkably in both hospital and community settings. This increase may be due to multiple factors, including inappropriate antibiotic usage, poor standards of environmental cleanliness, changes in infection control practices, large outbreaks of C. Diff infection in hospitals, alteration of circulating strains of C. Diff and spread of hypervirulent strains [20].

 

C. Diff is usually preceded by antibiotic use or chemotherapy [21]. However, in recent years, the epidemiology of the disease has shifted from almost exclusively infecting elderly patients who had been on antibiotics, to now infecting individuals of all ages with no recent history of antibiotic use [22]. Patients with C. Diff will commonly present with diarrhea, fever, raised white cell count and abdominal pain with distension [21].

 

Infection with C. Diff can be categorized as endogenous or exogenous. Endogenous infections originate via the carrier, while exogenous infection occurs through infected individuals, contaminated healthcare workers, nosocomial sources and contaminated environments [20]. C. Diff spores can survive harsh environments and common sterilization techniques. They are resistant to high temperatures, ultraviolet light, harsh chemicals, and antibiotics [19]. This is relevant to the R.T. as they have to ensure that proper sterilization techniques are utilized to clean equipment that has come into contact with infected patients to prevent exposure to subsequent patients.

 

Transmission of C. Diff

 

C. Diff is transmitted via the fecal-oral route [22]. The infectious dose is small and the bacteria is capable of producing spores that can remain viable for years in the environment [22]. Recently, it has been suggested that the inhalation of spores potentially provides a secondary mode of transmission [22]; however, this is unlikely to contribute to the disease’s overall epidemiology. After ingestion, the pathogen colonizes the gut and the individual typically sheds bacteria in their stool within two weeks [22].

 

C. Diff Radiology Specific Exams

 

Plain film: abdominal radiograph

Few findings may be seen early in the disease process. As the disease progresses, bowel dilatation, mural thickening and thumbprinting (radiographic sign of large bowel wall thickening) are seen. In untreated or fulminant cases, the disease will appear similar to toxic megacolon, with subsequent perforation and free intraperitoneal gas [21].

 

Thumbprinting on x-ray

Figure 3: Thumbprinting on x-ray. Courtesy Dr Omar Bashir, Radiopaedia.org. From the case Thumbprinting.

                     

Fluoroscopy: barium enema

The findings will be the same as plain film radiography. In addition, the pseudomembrane may be visible on double contrast studies [21]. The use of a barium enema has been significantly reduced in diagnosing C. diff due to the risk of perforation and the availability of CT [21].

           

CT

Findings include thickening of the bowel wall, the CT equivalent of thumbprinting, accordion sign, shaggy mucosal outline, pericolic stranding (minimal) and peritoneal free fluid [21]. Additionally, although the whole colon is usually involved in the disease process, the right colon and transverse colon may be affected in isolation in up to 5% of cases. In the vast majority of cases, 90 to 95%, there is also rectal involvement [21].

 

Axial CT scan of Accordion Sign
Figure 4: Axial CT scan of the midabdomen utilizing oral but not intravenous contrast demonstrates marked thickening of the colonic wall (white arrows) producing the so-called "accordion sign." There is a small amount of pericolonic stranding (red arrow) and ascites (green arrow). (Right) Axial CT scan through the pelvis shows marked thickening of the wall of the rectum (yellow arrows) indicating this is a pan-colitis. Published with permission from LearningRadiology.com.

 

Meningitis

 

Bacterial meningitis is a severe infection that is a medical emergency requiring immediate diagnosis and treatment [23]. Bacterial meningitis is an inflammation of the meninges, in particular the arachnoid and the pia mater, that is associated with the invasion of bacteria into the subarachnoid space [23]. The mortality rates of those that are infected are high; up to 34%, while up to 50% of survivors suffer from long-term sequelae, including: brain damage, hearing loss and learning disabilities [23,24]. There are various pathogens that can cause meningitis, including: Haemophilus influenza, Streptococcus pneumonia, group B Streptococcus, Listeria monocytogenes, and Neisseria meningitides [24]. Emerging antibiotic resistance is becoming a challenge for the medical community [23]. When a pregnant woman is infected with group B Streptococcus, she can pass the bacteria to her baby during labor or birth. Therefore, all pregnant women who test positive for group B Strep are given preventative antimicrobial treatment. This preventative measure, combined with the widespread use of conjugate vaccines has dramatically changed the epidemiology of meningitis [23].

 

Transmission of Meningitis

 

Bacterial meningitis is spread from the exchange of respiratory and throat secretions during close contact such as coughing or kissing [24]. Meningococcal bacteria cannot survive for lengthy periods outside of the body [24].

 

 

Patients with meningitis will usually present with the sudden onset of fever, headache, and neck stiffness. Often there are accompanying symptoms including nausea and vomiting, photophobia, and altered mental status [24]. The symptoms of bacterial meningitis typically develop within 3 to 7 days following exposure and may have a sudden onset or progress over several days [24].

 

Meningitis Radiology Specific Exmas

 

CT

A head CT provides information concerning intracranial complication such as brain edema, hydrocephalus and infarcts [23]. Further, bone window imaging identifies parameningeal foci such as sinusitis, mastoiditis or odontogenic abscess. Local infections are commonly seen in pneumococcal meningitis and may require surgical intervention [23].

 

There is on-going controversy regarding the role of head CT exams before lumbar puncture with the concern being the risk of cerebral herniation due to raised intracranial pressure [23,24]. Unfortunately, while increased intracranial pressure is a contraindication to lumbar puncture, normal CT scan results may not be sufficient to determine if the patient has normal intracranial pressure as the scans may be unremarkable [24]. At the present time, MRI is the most sensitive imaging modality as it allows for visualization of inflammation of the meninges as well as complications [24].

Head CT demonstrating enlargement of the temporal horns

Figure 5: Focal meningeal thickening and enhancement along the meninges in the right parietal convexity. Lesion is T2 hypointense. Case courtesy of Dr. Paresh K Desei, . From the case rID: 17597.

 

Tuberculosis (TB)

 

TB is one of the oldest known human diseases; and despite rapid advances in molecular diagnosis and drug therapies, it remains as the leading cause of death worldwide with nearly two million people dying each year from this disease [26, 27, 28]. It is estimated that between 19% and 43% of the world’s population is infected with Mycobacterium tuberculosis, which is the bacterium that causes tuberculosis infection and disease [28]. In the United States it is estimated that 15 million people are infected with M. tuberculosis, and although the case rate in the U.S. has declined during the past few years, there remains a substantial sized reservoir of patients who are infected with the bacterium in the country [28]. Without effective treatment for latent infection, new cases of TB can be expected to develop from this pool of patients in the upcoming years [28].

 

There are two types of TB conditions: latent TB infection and TB disease [29]. When TB bacteria live in the body and do not make the individual sick, it is called a latent TB infection. People with latent TB infection do not feel sick, do not have any symptoms and cannot spread the TB bacteria to others [29]. When the TB bacteria become active in the body and multiply, the person will go from having a latent TB infection to being sick with TB disease [29]. These patients have symptoms and can spread the disease to others. TB bacteria typically grow in the lungs and patients present with symptoms such as a cough lasting longer than three weeks, chest pain, and blood in the sputum [29]. Other symptoms that may be present include fatigue, weight loss, loss of appetite, fever, chills, and night sweating [29].

 

TB is a social disease with medical implications; it has always occurred disproportionately among disadvantaged populations, including the homeless, malnourished and overcrowded [28]. The risk of transmission of Mycobacterium tuberculosis from infected patients to healthcare workers is a neglected problem in many low and middle-income countries [30]. Research has found that there is a higher risk of acquiring TB disease in certain work locations (inpatient TB facility, laboratory, internal medicine and emergency facilities) and for certain occupation categories (radiologic technologists, patients’ attendants, nurses, ward attendants, paramedics and clinical officers) [30]. This issue does not seem to cross over into developed and higher income countries.. There is evidence to reinforce the need to design and implement simple and effective preventative TB programs in these lower income countries [30].

 

 

Transmission of Tuberculosis (TB)

 

Tuberculosis is transmitted from person to person through the air by droplet nuclei which are particles that are 1 to 5 μm in diameter that contain M. tuberculosis complex [28]. These nuclei are produced when patients with pulmonary or laryngeal tuberculosis cough, sneeze, sing or speak [28,29]. Further, they may be produced by aerosol treatments, sputum induction, aerosolization during bronchoscopy, and through the manipulation of lesions or processing of tissue or secretions in a hospital or laboratory [28].

 

People nearby may breathe in infected droplets and become infected. After inhalation, the droplet nucleus is carried down the bronchial tree and implants in a respiratory bronchi or alveolus [28]. Whether or not an infection develops depends on the bacterial virulence and the inherent microbicidal ability of the alveolar macrophage that ingests it [28]. The organisms grow for two to twelve weeks until they reach a number that is sufficient to elicit a cellular immune response that can be detected by a reaction to the tuberculin skin test [28].

 

Tuberculosis Radiology Specific Exams

 

The lungs are the most common site of primary infection by tuberculosis. The location of infection within the lung will vary based on the age of the patient and stage of the disease [31]. In children, the primary infection can be anywhere in the lung, whereas it has a predilection of the upper or lower zones of the lung in adults [31]. Post-primary infections have a strong predilection for the upper zones of the lung, and miliary tuberculosis is evenly distributed throughout the lungs bilaterally [31].

 

In patients with primary pulmonary tuberculosis the initial focus of infection can be anywhere in the lung, ranging in size from too small to be detected to possible lobar consolidation [31]. In most cases the infection becomes localized and a caseating granuloma forms, which calcifies eventually and is then referred to as a Ghon lesion [31]. In children, the most prominent finding is an ipsilateral hilar and contiguous mediastinal lymphadenopathy that is usually on the right. It is seen in over 90% of pediatric cases and in 10-30% of adult cases [31]. These nodes generally have low-density centers with a rim enhancement on CT. They may be large enough to cause compression of the adjacent airways, leading to distal atelectasis [31,32]. Pleural effusions are more frequently seen in adults (30-40% of cases), compared to pediatric patients (5-10% of cases) [31,32]. Calcification of nodes is found in 35% of cases. When a calcified node and a Ghon lesion are found, it is known as a Ranke complex [31].

 

Post-primary tuberculosis within the lungs usually develops in the posterior segments of the upper lobes or in the superior segments of the lower lobes [31]. Post-primary infection commonly appears as patchy consolidation or poorly defined linear and nodular opacities [31]. Post-primary infections are more likely to cavitate than primary infections and they usually develop in the posterior segments of the upper lobes [31,33,34]. If an air fluid level develops, it means that there is communication with the airway, and therefore there is the possibility of contagion. Endobronchial spread along the nearby airways results in a ‘tree in bud’ appearance on CT [31]. Hilar nodal enlargement is only seen in one third of cases. Lobar consolidation, tuberculoma formation and miliary TB patterns may be found with post-primary infections, but are less common [31].

 

Miliary tuberculosis is uncommon and carriers a poor prognosis as it represents haematogenous dissemination of an uncontrolled TB infection [31]. It can be seen in both primary and post-primary infections. Implants of the infection can be found throughout the body, however, the lungs are usually the easiest sites to image [31]. The miliary deposits appear as nodules that are 1 to 3 mm in diameter, which are uniform in size and uniformly distributed [31].

 

Rarely an isolated tracheal TB infection can be seen on imaging. Findings show irregular circumferential mural thickening, which is usually the result of a contagious inflammation from an adjacent nodule [31].  Further, a broncholith is also uncommon; however, it is due to the erosion of a calcified lymph node into a bronchus, which results in calcified material entering the lumen. This material may be coughed up by the patients (lithoptysis) [31].

 

An anteroposterior X-ray of a patient diagnosed with advanced bilateral pulmonary tuberculosis.

Figure 6: An anteroposterior X-ray of a patient diagnosed with advanced bilateral pulmonary tuberculosis. This AP X-ray of the chest reveals the presence of bilateral pulmonary infiltrate (white triangles), and caving formation“ (black arrows) present in the right apical region. The diagnosis is far-advanced tuberculosis. This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL), with identification number #254.

 

Ebola

 

Ebola virus disease (EVD) (formally known as Ebola hemorrhagic fever) is a highly contagious, severe disease that is often fatal [35,36]. Case fatality rates have varied between 25% and 90% in past outbreaks [36].  Initially, patients may report non-specific, flu-like symptoms including fever, myalgias and general malaise. This is followed by nausea, vomiting, diarrhea, rashes that progress to petechiae (bleeding under the skin that results in small, red dots), conjunctival hemorrhage, epistaxis (bleeding from the nose), melena (black, tarry feces), hematemesis (vomiting blood), shock and encephalopathy [35, 36].

 

Of concern to R.T.s is the fact that healthcare workers have been frequently infected while treating patients with confirmed or suspected EVD when proper infection control precautions are not strictly practiced [35].

 

Transmission of Ebola

 

Ebola virus (EBOV) spreads among humans through direct contact with blood or other body fluids from an infected individual (alive or deceased), or through exposure to objects that have been contaminated with fluids or secretions from an infected individual with active disease. The spread of the EBOV only occurs when the patient is symptomatic [35]. No airborne transmission of EBOV has been reported [35].

 

The incubation period for EBOV is 2 to 21 days and humans are not infectious until they develop symptoms of the disease [35].

 

Diagram of Symptoms of Ebola

Figure 7: Diagram of Symptoms of Ebola. Courtesy Mikael Häggström [CC0], via Wikimedia Commons.

 

Ebola Radiology Specific Exams

 

There is currently no data on specific imaging features of Ebola [37]. Rather, the role of medical imaging in Ebola care is to exclude other diagnoses or assess complications of the infection [36]. There needs to be a delicate balance of providing the best possible medical care to the infected patient, while maintaining full protection of the medical staff. Radiologists from the National Institutes of Health (NIH) and Emory University School of Medicine have issued a special report outlining their protocols and recommendations related to the preparedness for handling cases of Ebola virus in hospitals in the United States. It is generally supported that the best way to accomplish this is to provide medical imaging exams to patients infected with EBOV only within a specialized isolation unit [36].

 

Portable X-ray units and bedside ultrasonography (US) scanners have been used in biocontainment units. Training and implementation of this type of equipment in isolation needs to involve close co-ordination with radiology personnel. Staff who will be working in the isolation unit are initially identified through Ebola virus disease (EVD) planning sessions. These staff members receive in-depth information on the background and spread of the disease, as well as isolation unit procedures [36]. 

 

Radiology departments across the U.S. must develop standard operation procedures for performing imaging procedures in isolation. These procedures will vary depending on the equipment that is available, whether the facility is equipped with wired or wireless image transmission, and the complexity of the case [36]. At the present time, two strategies exist. To understand these strategies, the R.T. must understand the terminology when discussing locations in the healthcare facility. The hot room is where the infected patient is located, the cold area is the area where no personal protective equipment is needed and the warm room is the area that separates the hot room from the cold area. In the first strategy, the technologist does not enter the patient’s room (hot room); rather, they stay in the warm room and provide verbal instructions to nurses or physicians in the hot room [30]. In the second strategy, the radiographic technologist enters the hot room to assist with operating the imaging equipment. The second approach is sometimes necessary for more complex imaging procedures [36]. The report stresses that every effort should be made to perform general radiographic procedures in the isolation room rather than attempting to transport the patient to the radiology department [36]

 

If a patient needs to be transported to the radiology department, additional precautions must be taken, including coordinating the transportation route with the hospital’s infection control team [36].

 

Measles

 

The measles virus is a highly infectious disease that can spread rapidly [38,39,40]. Significant progress has been made toward reducing the number of deaths caused by this disease through the introduction of the measles vaccines. However, this progress is being threatened by the failure to maintain high levels of measles vaccine coverage [39].

 

Patients with measles typically present with symptoms including fever, maculopapular rash, cough, coryza and conjunctivitis [38]. These symptoms can persist for 5 to 6 days. Measles may lead to secondary infections such as otitis or pneumonia, or to serious complications such as encephalitis (1:1000 cases) and death (1:3000 cases) [38].

 

Measles with 4 day rash

Figure 8: Classic day 4 with rash. Courtesy CDC/NIP/Barbara Rice (http://phil.cdc.gov/phil/ (ID#: 132)) [Public domain], via Wikimedia Commons


Transmission of Measles

 

Measles is spread by coughing and sneezing, close personal contact or by direct contact with throat or nasal secretions [40]. The virus remains active and contagious in the air or on infected surfaces for up to two hours. An infected individual can transmit the virus from four days prior to the onset of the characteristic rash of the disease to four days after the rash appears [40].

 

Measles Radiology Specific Exams

 

Most patients infected with measles do not require imaging tests; however, they may be needed in rare instances when complications arise, as is the case when the patient develops subacute sclerosing panencephalitis (also known as Dawson disease). This is a rare chronic, progressive and fatal encephalitis that typically affects children and young adults. It is caused by a persistent infection of immune resistant measles virus [39].

 

Radiographic features depend on the stage of the disease. In the acute stage, patchy asymmetric regions of white matter involvement are visualized, usually in the temporal and parietal lobes of the brain [39]. Over time, more extensive white matter involvement develops as the corpus callosum and basal ganglia become affected. Eventually, a generalized encephalomalacia develops and parenchymal loss may be seen in the late stages of the disease [39].

 

 

Subacute sclerosing panencephalitis on MRI

Figure 9: Subacute sclerosing panencephalitis on MRI. A and B represent focal abnormality in subcortical white matter (arrows) on initial scan. C (arrows) shows advanced cortical atrophy 3 months later while D demonstrates less obvious focal abnormality than earlier exam (arrow).  Bonthius D, Stanek N, Grose C/ CDC - Bonthius D, Stanek N, Grose C (2000). "Subacute sclerosing panencephalitis, a measles complication, in an internationally adopted child". Emerg Infect Dis 6 (4): 377-81. PMID 10905971.

 

Standard Precautions

 

Infections associated with healthcare settings are a critical challenge for the public health sector. Most infectious diseases are acquired through contact with infected patients, predominantly with the hands of healthcare personnel, including physicians, nurses, personal support workers and R.T.’s [42, 43]. Therefore, hand hygiene is the single most effective measure for preventing and controlling infectious diseases [42]. Healthcare facilities must promote compliance with correct hand hygiene through appropriate education programs.  Further, they must provide adequate areas and hand hygiene products for personnel to use [42].

 

The Centers for Disease Control and Prevention (CDC) recommends standard precautions and contact precautions for preventing the spread of infectious disease [3]. Standard precautions are based on the principle that all blood, body fluids, secretions, excretions (except sweat), non-intact skin and mucus membranes may contain infectious agents [3].

 

 

 

 

 

TABLE 1: Centers for Disease Control and Prevention Guidelines for Standard Precautions [3]

Precaution

Scenario

Hand hygiene

After contact with blood, body fluids, secretions, excretions, contaminated items; before donning gloves and after removing gloves; between patient contact

Personal Protective Equipment

 

Glove

When contacting blood, body fluids, secretions, excretions, contaminated items, mucus membranes, and nonintact skin

Gown

When skin or clothing contact with blood, body fluids, secretions, excretions, or contaminated items is anticipated

Mask, eye protection, face shield

When there is a risk of splash or spray of blood, body fluids, secretions, or excretions (e.g. suctioning and endotracheal intubation); if aerosol generating procedure, need N95 mask

Soiled patient care equipment, textiles, and laundry

Handle in a manner that minimizes the transfer of microorganisms; wear gloves if equipment is visibly contaminated; use hand hygiene

Environmental control

Routine care, cleaning, and disinfection of surfaces, especially frequently touched or proximity surfaces

Needles and sharp objects

Do not recap, bend, break, or hand-manipulate used needles; dispose of sharps in a puncture-resistant receptacle

Patient resuscitation

Use mouthpiece, resuscitation bag, or other ventilation devices to prevent contact with mucous membranes and oral secretions

Respiratory hygiene

Instruct symptomatic individuals to cover mouth or nose when sneezing or coughing; use tissues and dispose of them in no-touch receptacles; use hand hygiene if contact with respiratory secretions; wear surgical mask, if tolerated or maintain spatial separation (> 3 feet if possible)

 

 

 

 

 

 

 

 

 

 

TABLE 2: Recommendations on Methicillin-Resistant Staphylococcus Aureus infection (and other multi-drug resistant infections) Control in the Radiology Department [3]

Department Location

Recommendation

All Areas

Establish administrative support and fiscal commitment to facilitate implementation of infection control practices and foster a departmental culture of infection prevention and control

 

Establish and maintain an ongoing process of staff education to reinforce policies and introduce new guidelines as they arise

 

Consult with experts, such as public health officials or hospital infection control personnel, to ensure departmental protocols are up to date

 

Adhere to routine hand hygiene practices for all patients and staff in all areas of the department; have alcohol-based hand rubs available for use by patients and healthcare personnel

 

Continue with standard general housekeeping and disinfecting for all areas of the department

 

Establish a surveillance program for infection rates or infection transmission rates, especially in the interventional section of the department, provide feedback to staff

 

Routinely audit the department to assess staff adherence to infection control policies and establish an incentive and sanction system to encourage adherence

Patient registration

Ensure that processes are in place for the identification of colonized or infected patients

 

Move colonized or infected patients who have active fluid drainage to an imaging room as soon as possible

Patient imaging

Use standard and contact precautions, such as gown and gloves, when providing diagnostic and interventional imaging services to colonized or infected patients; specific guideline on prevention of intravascular catheter-related infections are available

 

Protect portable and stationary imaging equipment from contact with body fluids by using plastic covers or bags when possible

 

Perform adequate cleaning and disinfection of imaging equipment and computer hardware, with enhanced cleaning for high-contamination-risk cases

Patient transportation

Use standard and contact precautions for both intradepartmental and extradepartmental transportation

 

It is also imperative to exercise proper infection control practices for diagnostic imaging equipment, such as ultrasound, CT, and MRI. Several studies have shown that ultrasound probes act as vectors for nosocomial infection [3]. Furthermore, it has been found that the MRI unit requires special attention after working with patients infected with MRSA, and other infectious pathogens, due to the long bore and difficult access of the machine. Applying a hypochlorite-cleaning agent with a long-handled brush to clean the bore of the machine will decontaminate the machine appropriately [10].  These examples highlight the importance of rigorous cleaning after examinations of infectious disease patients

 

Furthermore, in CT, MRI and radiography, it is important that the R.T. know the infection status of the patients so that standard precautions and contact precautions can be taken. This allows the R.T. to cover equipment when possible and ensures that proper cleaning protocols are followed after the examination to prevent the spread of infection to subsequent patients [3]. Additionally, other items in the examination room, such as the control station and computer keyboards, should be properly cleaned and disinfected after working with infectious disease patients [3,44].

 

Another potential threat to infectious disease spread is non-compliance of infection control precautions by healthcare personnel. Ineffective communication of a patient’s infection status during patient transfers is a potential cause of non-compliance with infection control precautions by healthcare personnel. Simple measures to enhance communication, such as the provision of a check list and the use of colored lines can allow for significant improvement in the compliance with infection control protocols by transport personnel during inpatient transfers to radiology departments [30]

 

Discussion

 

Pathogenic microorganisms, such as bacteria, viruses, fungi and/or parasites, cause infectious diseases. Sometimes infections with these organisms result in mild infections that are self-limiting; however, there are times when the infections are severe and possibly deadly.

 

Infectious diseases are a concern for healthcare facilities and for radiology departments as they are often a high-traffic area for patients, visitors and healthcare workers. This article has discussed common concerns, transmission, standard precautions and specific radiographic tests used for various infectious diseases, including: Methicillin-Resistant Staphylococcus aureus (MRSA), Hepatitis, Clostridium difficile (C. diff) meningitis, tuberculosis (TB), Ebola, and measles. The participant should be able to apply the knowledge gained from this article to their workplace to help minimize the spread of infection.

 

 

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