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Author: Sarah Williams, PhD
Abstract: The development and expansion of advanced medical imaging techniques has led to vast improvements in diagnostics and treatment monitoring for a wide variety of conditions that span all age ranges. Given that the vast majority of these imaging devices were first developed for adult populations, pediatric patients are now presenting unique challenges in how to evaluate tiny bodies and organs on equipment that was designed for adults. This article serves as a continuing education activity for registered technologists (RT) with an emphasis on these unique considerations necessary when imaging younger patient populations. The most commonly used methodologies within pediatric populations are reviewed and include ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI).
This article was designed as a continuing education (CE) activity and the focus has been placed on the topic of age specific care for young patients. Participants will be able to discuss unique concerns with regard to radiation safety and general pediatric patients. Participants will also be able to identify the important factors to consider prior to performing general imaging on a pediatric patient, as well as be able to define several common imaging modalities and techniques that are commonly used with pediatric patients. A technologist may benefit from improved understanding of common pediatric conditions, including main features and signs, as this is likely to inform their choice of equipment, ability to adapt the equipment and patient positioning, and skill in optimizing dose and technical settings.
The development and widespread availability of medical imaging techniques has had a significant impact on the diagnosis and treatment of numerous medical conditions affecting both pediatric and adult populations. Given that medical imaging provides, in particular, a noninvasive method for gathering diagnostic information and monitor treatment progress, these techniques have become increasingly important among pediatric populations. Moreover, the benefits of these procedures have been well established within both the adult and pediatric literature through more than a century of diagnostic imaging studies [1-3]. In fact, the use of medical imaging is believed to be associated with reduced morbidity rates, availability of additional treatment options, and increased life expectancies, by providing early detection of diseases, improved diagnosing, and better monitoring of therapy [4-5].
The scope of pediatric radiology is quite broad. Clinical indications of these imaging techniques include the diagnosis and assessment of diseases affecting the central nervous system, cardiopulmonary, endocrine, gastrointestinal, lymphatic, genitourinary, and musculoskeletal systems . Pediatric imaging procedures are ordered by practioners for diagnosing and assessing oncologic diseases, as well as for interventional procedures (e.g., image-guided placement of catheters, stents, or other devices within the body; removing blood clots or other blockages) [6-7]. Indeed, these techniques have received much support for their benefits in aiding both the diagnosis and treatment for a variety of conditions and, in the last decade, use of imaging techniques has grown rapidly. Despite these high rates of imaging utilization, many of these procedures involve a certain degree of risk, as they require the use of ionizing radiation. Technologists must be appropriately trained and take the necessary precautions in order to reduce any potential risks associated with unnecessary exposure to dangerous radiation.
While radiation safety and concerns regarding unnecessary exposure to radiation are critical across all ages, they are particularly important among pediatric patients. According to guidelines established by the Food and Drug Administration (FDA), medical imaging exams should be performed only after carefully considering whether the procedure is necessary to provide diagnostic clarification, answer a clinical question, or guide treatment of the disease . Moreover, even when it has been determined that the clinical benefit of the procedure outweighs the risk associated with potential radiation exposure, ongoing caution must be taken in order to minimize this risk with pediatric patients by following these standards:
- Provide the family with detailed information regarding the rationale for using ionizing radiation imaging and ensure that the patient and/or parent or guardian have a clear understanding of both the benefits and risks of the procedure.
- Reduce the number of inappropriate referrals by:
- Determine whether an imaging evaluation is necessary to answer a clinical question;
- Consider the appropriateness and availability of alternative imaging procedures, which are associated with less or no radiation exposure (such as US or MRI); and
- Review the patient’s history of medical imaging, in order to avoid performing duplicate exams.
- Ensure that the equipment is appropriate for use with pediatric patients and, if possible, consult the manufacturer for information on how to properly configure the equipment for smaller patients.
- Use protocols and technique charts that are specific for pediatric patients, where possible. Should pediatric-specific protocols and technique guidelines not be available for a particular device, consult with the manufacturer or other pediatric imaging expert for assistance on the appropriate use of the device with smaller patients.
- For existing equipment that may not have specific modifications or guidelines for pediatric use, consult the general recommendations available through the Alliance for Radiation Safety in Pediatric Imaging. These recommendations provide suggestions on how to properly configure existing equipment for use with pediatric patients.
- Monitor doses given to patients and confirm the facility doses against the published diagnostic reference levels, where available.
Optimization of the imaging examination for pediatric patients should be performed carefully, as the optimal exposure setting may be a range, depending on equipment capability and requirements for image quality by the physician . While the FDA’s Center for Devices and Radiological Health considers the age range for the pediatric population to span from birth to 21 years, the most important factor to consider when optimizing the radiation exposure is the patient’s size . This is largely due to degree of radiation absorption, as children may receive higher doses when compared to adults due to higher intake (likely due to inadequate optimization of the imaging equipment for the smaller body size of a child patient, resulting in a higher than necessary dose of radiation) and accumulation .
Younger patients, in particular, are considered to be more sensitive to radiation than their adult counterparts. While the mechanism for this elevated sensitivity is not fully understood, it may be associated with the rapid rate of cell division that occurs within the growing and developing tissue of pediatric patients . The tissue of very young patients is also considered to be more radiosensitive because it is less differentiated than the tissue of older children and adults. Finally, pediatric patients present with longer life expectancies following the imaging procedure, thus allowing for longer incubation time and the development of cancer-causing tumors.
Some research has suggested that children are up to 10 times more sensitive to ionizing radiation than adult patients . Lifetime estimates have indicated that pediatric patients are placed at a significantly greater risk of developing terminal cancer than adult patients per unit of radiation dose . Moreover, many believe that there is no low-dose threshold for the risk of developing cancer and, as such, no amount of radiation should be treated as completely safe[14-15].
While the estimated cancer risk per unit dose of ionizing radiation is significantly higher in pediatric patients than in adults, the overall risk for developing cancer following medical imaging exposures is quite low regardless of the patient’s age. Nonetheless, proper optimization of the scanning parameters to obtain appropriate image quality, while adhering to the Federal Regulations of “as low as (is) reasonably achievable” (ALARA), should be ensured at all times for techniques that utilize ionizing radiation. Ideally, alternative imaging techniques, which do not carry the same risk for ionizing radiation exposure, are considered in pediatric patients.
Types of Imaging
While functional neuroimaging techniques, such as positron emission tomography (PET) or single photon emission computed tomography (SPECT), have been readily available for the last several decades, many of these techniques are not appropriate for use with pediatric patients . Conversely, growing popularity of alternative and noninvasive procedures, such as functional magnetic resonance imaging (fMRI), now has prompted a surge of new investigations on the use of radiography to evaluate the internal anatomy and pathology in populations of typically developing and non-typically developing youth. For those patients, in whom pathology is suspected, the goal of the procedure is then to confirm the presence or absence of the disease or trauma, as well as to establish the nature of the disease and its progression. The most common types of imaging utilized among pediatric populations are outlined below.
One imaging technique that is regarded as ideal for use with pediatric populations is US. US imaging utilizes high-frequency sound waves to produce images of internal structures, rather than ionizing radiation . Thus, a small transducer, or probe, is placed directly on the skin, along with US gel. The device transmits high-frequency sound waves through the skin, into the body. As these sound waves bounce off of, or echo back from, internal tissue and organs, it is collected and displayed as an image on the computer screen. There are several types of transducers available for use during an US procedure. Factors influencing the selection of an appropriate transducer include the patient’s particular body habitus and location of the abnormality. Higher frequency transducers (7.5-17.0 MHz) can be used with infants and children to produce very high-resolution images . With recent advancements in technology, US devices now feature graded-compression sonography, along with vast improvements in gray scale (used most frequently; ideal for performing chest imaging and visualizing many types of internal abnormalities) and color Doppler (ideal for instances when distinguishing between vascular and nonvascular tissue masses is required) techniques [17-18]. Graded-compression refers to a technique in which gentle pressure is applied to the area being scanned using the US probe or palpation from the hands in order to reduce the distance between the US probe and the pathology of interest. The images provided during an US can include valuable information that will aid in the differentiation between those conditions that require immediate surgical attention and those that may be well managed with more conservative approaches.
Given that pediatric patients tend to have less fat and their bodies are much smaller in size, high-resolution images of the internal structures, including the organs and blood vessels, are easily achieved from the US transducer . Other benefits of US imaging technology with pediatric patients include its ease of performance, ability to display images on a monitor in real-time, and relatively infrequent need for patient sedation during the procedure. US is also affordable, non-invasive, and portable. In fact, diagnostic information is available from an US exam to the physician in real time, minimizing any undue stress caused to a child needing imaging. Limitations in terms of the depth of penetration and field of view, prevent US from providing adequate information to be used as a screening tool. As such, US imaging is best when a targeted evaluation is necessary within a specific region of the body.
In order to optimize imaging of the targeted area, proper position of the patient is required. Indeed, the age of the child can have an effect on the acoustic window for US imaging. For instance, during early childhood the sternum and the ribs are finalizing ossification. Until this occurs, however, the cartilage from which they have formed provides an ideal acoustic window, particularly when it is necessary to image the internal mediastinal structures. It is recommended that towels and pillows be employed in order to ensure proper positioning of the patient prior to beginning the actual imaging procedure.
The three most common conditions, which may warrant performing an US evaluation with a pediatric patient include:
- Appendicitis: Appendicitis has the highest incidence rate among children between the ages of 5 and 15 years of age, and is historically the most common cause of emergent surgery during childhood [19-20]. It should be noted that it is not uncommon for young children to have difficulty reporting on their symptoms. When performing an appendiceal US, a high-resolution linear-array transducer (5-12 MHz) is used . Initial positioning of the transducer can be made according to the child’s report of pain . Pressure is then applied in a gradual manner using the transducer, in order to displace the bowl loops. A normal appendix should have an outer wall with a diameter of 6mm or less and the lumen should, at a minimum, partially collapse with pressure.
- Intussusception: Intussusception is the most commonly occurring acute abdominal complaint in infancy and childhood . Age of onset ranges from 5 to 9 months of age. It is quite rare for the condition to present in patients younger than 3 months of age or older than 3 years old . Many children who were ultimately diagnosed with intussusception did not report pain at the time of the diagnosis. As such, imaging is regularly required for diagnosis . There is support for the reliability of US in diagnosing intussusception, utilizing the graded-compression technique .
- Hypertrophic pyloric stenosis: Hypertrophic pyloric stenosis tends to emerge most frequently between the 3rd and 12th weeks postnatal . Diagnosis of hypertrophic pyloric stenosis is typically done through palpation of a mass the shape of an olive within the epigastrium. This can often be time-consuming, as the task requires that the infant patient is relaxed and quiet. As such, many clinicians now rely upon imaging techniques for diagnosing hypertrophic pyloric stenosis. US imaging is done with a high-resolution transducer (5-12 MHz) positioned in a transverse oblique plane parallel to the right lower costal margin . The most important criteria in diagnosing hypertrophic pyloric stenosisare the persistent and abnormal thickening of the pyloric muscle.
Other childhood conditions that may be assessed using US imaging include:
- Other gastrointestinal tract conditions
- Urinary tract conditions
- Renal disease
- Alignment difficulties (such as spina bifida or hip dislocations)
- Hydrocephaly (abnormal accumulation of cerebrospinal fluid on the brain)
- Intracranial hemorrhage (blood vessel bursts within the skull)
Computed Tomography Imaging
Over the course of the last two decades the use of CT imaging has increased drastically, even among pediatric populations. High-quality radiology images are now accessible at a rapid pace. While this widespread use of CT led to advances in the diagnostic capabilities of many childhood disorders, indeed, there is a certain degree of risk associated with this procedure. In particular, it has been estimated that CT delivers 100 to 150 times greater doses of ionizing radiation when compared to conventional radiography.
This is particularly concerning when this procedure is applied to populations of children, as children are significantly more sensitive to radiation-induced carcinogenesis (as described above) and have a longer life span during which they may develop cancer. In order to best optimize the scanning parameters, the radiology technologist must have a firm understanding of the technical aspects of the CT procedure . It has been suggested that the most effective method for reducing radiation dose risk in children is to target unnecessary referrals. Nonetheless, the use of pediatric CT has received support in reducing the need for emergency and exploratory surgeries, which are known to be associated with a high degree of risk. Further, CT imaging can quite easily distinguish between very small soft tissue densities, such as those commonly present in child patients.
In light of reducing unnecessary risk in pediatric patients, it is recommended that alternative methods be explored when imaging is necessary . For instance, physicians and other practitioners are generally encouraged to consider the appropriateness of an US first, as this procedure does not require potential exposure to radiation. Repeat imaging, for instance. as a method for monitoring disease progression, is not recommended. Should the technologist feel as though a particular referral for imaging is unnecessary, the technologist may wish to discuss these concerns with the radiologist. In some instances, the technologist may even contact the ordering physician or practitioner to confirm the need for the imaging.
As noted above, pediatric patients are especially susceptible to exposure to excessive radiation, given the need to tailor the settings to a much smaller body. This includes consideration for the level of the dosage itself, as well as the volume of the coverage area, which can quite frequently be over estimated. One of the most common ways a pediatric patient might be placed at risk for excess radiation exposure during a CT imaging scan is by failing to decrease the tube-current-time product (mAs) in accordance with the patient’s smaller size. Guidelines for appropriately modulating the tube current as a function of the patient’s size are generally provided in the operator’s manual and may be referred to as a ‘technique chart.’ Some modern scanners are now equipped with either automatic or semiautomatic correction of mAs according to the patient’s size.
Lower settings of tube voltage potential (kVp) may also be recommended for CT imaging with pediatric patients, owing to less attenuation in the body. For most children whose body weight is 45kg or less, kVp values of between 80 and 100 are typically acceptable, while adolescents may require up to 120 kVp, for instance, when imaging the abdomen. In some cases, values as low as 60 kVp may even be ideal.
The three most common conditions that may warrant orders for CT imaging on a pediatric patient include:
- Head trauma: Trauma and injury to the head is quite common during childhood. In fact, most childhood head trauma injuries are mild in severity, though there is a small portion of cases that present with outward symptoms of minor injury that end up having clinically significant tissue trauma internally and, thus, require diagnostic imaging using CT. RTs’ must be well informed of the risks uniquely associated with radiation exposure among pediatric patients. Further, technologists must receive proper education and training in any and all procedural modifications necessary for performing CT imaging with this patient population. While a more in depth discussion on imaging children of suspected abuse is provided below, it is important to note here that all pediatric patients whose head trauma is believed to be the result of abuse must undergo imaging. Skull radiographs may be used as a screening tool for fractures. Once it has been determined that the radiograph is positive for the presence of skull fractures, then a head CT should be ordered. Every attempt should be made to avoid imaging studies utilizing ionizing radiation, which includes CT and other x-rays, in children under 2 years of age. Techniques such as the US or MRI do not employ the use of radiation and, as such, may be more appropriate in terms of risk for use with populations of patients this young.
- Headaches: The use of CT imaging is not recommended as a diagnostic tool for pediatric patients presenting with headache pain and no other signs or symptoms. Conversely, imaging is indicated in patients presenting with headache pain and are under 3 years of age. Other indications that a CT scan may be warranted include severe pain that persists for several days, headache pain that is accompanied by changes in behavior or mental status, pain that wakes the patient from sleep, nausea, and vomiting.
- Abdominal and Pelvis: CT is the preferred cross-sectional imaging technique for evaluating abdominal and pelvic trauma. In many instances, CT can be used as an adjunct or follow-up to US. Abdominal and pelvic CT is indicated for hollow viscera, conditions affecting the liver and gallbladder, pancreas, kidneys, adrenal gland, spleen, pelvis, or abdominal structures (such as mesentery, omentum, peritoneum, retroperitoneum, vascular, abdominal wall, diaphragm).
Other common conditions, which may be diagnosed by CT include:
- Chest wall abnormalities
- Extracardiac vascular disorder
- Cardiac disease
- Tracheobronchial abnormalities
- Mediastinal congenital masses and abnormalities
- Lung parenchyma (including infection, lung disease, congenital pulmonary abnormalities, and traumatic injury)
- Bone lesions and fractures that were not adequately assessed by radiographs
- Evaluation of orthopedic implant complications
- Assessment of musculoskeletal alignment deformities
- Bone marrow and soft-tissue pathology
Magnetic Resonance Imaging
MRI is a medical imaging technique that has received support as an effective tool for detecting, evaluating, assessing, staging, and following-up on diseases. This imaging technique can be used to inform the diagnosis, as well as provide useful information to guide treatment planning and prognosis, when performed and interpreted properly. MRI has the capability of providing more specific details with regard to underlying soft tissue through ideal three-dimensional anatomic representation, tissue characterization, and quantitative/functional capabilities. Moreover, the MRI procedure is particularly preferred for use with pediatric populations, as it is noninvasive and does not involve exposure to ionizing radiation [29-30].
As with all other imaging techniques, there are some drawbacks to performing an MRI on pediatric patients . Primarily, it is not uncommon for pediatric patients to require sedation or anesthesia prior to undergoing the MRI. Children, especially younger children, can often become anxious about having to be positioned into an enclosed space or about the loud noise from the scanner itself. Often, having a parent, relative, or other familiar adult present along with the patient can help ease discomfort. Should the patient not easily calm with a familiar face present, technologists may wish to consult with the Child Life team for their expertise and assistance in helping the child cope with their anxiety regarding the scanning procedure. In most instances sedation is required for pediatric patients, given the extended scan times and need to remain very still for the duration of the scan. Previous estimates have suggested that up to 90% of pediatric patients require some type of sedation or anesthesia to reduce their anxiety during an MRI.
The following list contains (but is not limited to) some primary indications for MRI:
- Chest: Inherited diseases, which increase the risk for vascular disorders; congenital vascular abnormalities; known or suspected mediastinal processes; chest wall disorders; pulmonary parenchymal
- Abdomen: Neoplastic conditions; vascular malformations; known or suspected conditions affecting the liver, spleen, pancreas, adrenal gland, or kidney; known or suspected biliary disorder; congenital or acquired urinary obstruction; abnormal renal function; urinary tract anomalies; inflammatory bowel disease; diffuse liver disease; vascular mapping; abdominal wall disorders
- Pelvis: Genital tract abnormalities; anorectal malformations; inflammatory conditions affecting the pelvic organs; suspected arterial or venous thrombosis; pelvic inflammatory conditions
- Shoulder: Acute or chronic trauma; bone fracture complications; avascular necrosis or bone infarct; known or suspected bone or soft tissue abnormality; arthritis; congenital malformations; unexplained persistent pain and/or swelling; suspected bone marrow abnormality; postoperative evaluation
- Elbow: Acute and/or chronic trauma; bone fracture complications; osteochondral lesions; known or suspected bone or soft tissue condition; bone, soft tissue, or articular infection or inflammation; known or suspected arthritis; congenital malformations; unexplained persistent pain and/or swelling; suspected bone marrow abnormality; postoperative evaluation
- Hand and Wrist: Acute and/or chronic trauma; bone fracture complications; osteochondral lesions; known or suspected bone or soft tissue condition; bone, soft tissue, or articular infection or inflammation; known or suspected arthritis; congenital malformations; unexplained persistent pain and/or swelling; suspected bone marrow abnormality; postoperative evaluation
- Knee: Acute and/or chronic trauma; osteochondral lesions; bone fracture complications; known or suspected bone or soft tissue condition; avascular necrosis or bone infarct; bone, soft tissue, or articular infection or inflammation; known or suspected arthritis; congenital malformations; unexplained persistent pain and/or swelling; suspected bone marrow abnormality; postoperative evaluation
- Foot and Ankle: Acute and/or chronic trauma; bone fracture complications; osteochondral lesions; known or suspected bone or soft tissue condition; bone, soft tissue, or articular infection or inflammation; known or suspected arthritis; congenital malformations; unexplained persistent pain and/or swelling; suspected bone marrow abnormality; postoperative evaluation
General Imaging Considerations for Pediatric Populations
In the following section, several specific considerations regarding the use of imaging techniques within the general pediatric population are outlined and reviewed.
Though it has not always been the case, it is well accepted that pediatric patients are not simply smaller scaled versions of adults. This population of patients has much smaller bodies and organs, whose proportional ratios do not match those of an adult patient. While the organs of pediatric patients continue to grow and develop, some even occupy different relative positions within the body than in adults. Pediatric patients also present with differing heart and respiration rates, different proportional ratios of fat and connective tissue, varying biomechanical loads, and even diseases that are unique to the population (illnesses that emerge during childhood, organ dysfunction without apparent tissue damage, immaturity, congenital anomalies, etc.). Given these factors, there are many special considerations to be made when imaging pediatric patients, all of which require adaptation, skill, and experience on behalf of the imaging technologist. It is not uncommon to require some form of deviation from routine protocol in terms of dose administration, type of image needed, and technique.
Positioning of the patient and ensuring immobilization can be a critical consideration when imaging pediatric populations, as children have a difficult time with compliance when being positioned and during image capture. This can lead to issues with regard to the positioning of the body, leading to a misalignment of the anatomy in the image. In fact, some systems are affected by a misalignment due to the way the software handles the image. An immobilization device may be necessary to ensure that the appropriate images are gathered and to avoid repeated procedures. When using immobilization devices, however, proper care must be taken to ensure that the device has not caused any artifacts on the digital image receptors. Toys, books, or other distraction tools can be invaluable for supporting the compliance of young patients with the positioning requirements of the imaging procedure.
Specific consideration may be required for pediatric patients in terms of preparation for the examination and performance. Of note, appropriate NPO status should be assured, given that moderate sedation or general anesthesia may be necessary for the procedure. In some instances, contrast media may be necessary. It is recommended that IV contrast enhancement be performed using the appropriate injection protocols and guidelines established by the American College of Radiology (ACR).
While in some instances it may be beyond the control of the RT, single-phase imaging should be considered the standard rather than the exception when performing CT imaging with pediatric patients. This serves to minimize multiple scans and limit unnecessary radiation exposure, as typically one scan is enough. Scans should also be restricted to only the necessary coverage area. Further, adjustments should be made to the CT scan parameters to account for the size of the patient, the region to be scanned, and the clinical indications. This includes making adjustments to the beam collimation, tube current, gantry cycle time, pitch, and peak kilovoltage (kVp). In pediatric populations, APR and exposure charts require adjustment to account for both premature infants, as well as obese adults. Optimal kVp must be carefully selected in order to ensure that the x-ray beam will penetrate the patient’s anatomy. This is also critical for pediatric patients as the tissue within their bodies tends to image with less contrast. Nonetheless, given that the bones of pediatric patients are less calcified than those of adults, a lower kVp may be required.
In terms of imaging techniques that require x-rays, it is critical to take into account the ways in which relevant factors associated with pediatric populations can affect the attenuation of the x-ray beam. This forms the foundation by which images from both digital and radiological imaging are produced. In particular, the thickness of the tissue within the body, body habitus, and the composition of the tissue can all lead to disturbances in beam attenuation of the x-ray.
For all imaging techniques conducted with pediatric patients, the growth and development of patient must be taken into account. Growth rates along the age continuum vary widely. Moreover, a child’s individual body parts grow and develop along individual timelines. For instance, the skull of an infant grows at a much slower rate than the femur when compared proportionately to adults. In general, grids are not used when the patient’s tissue is less than 10cm thick. Thus, consideration for the actual size of the patient and their individual tissue composition must be done prior to using grids for imaging.
Neonatal General Considerations
Neonatal imaging requires many special considerations. The term neonatal refers to an infant who is in their first month of life following delivery. It is not surprising that imaging of neonates must take into careful consideration the challenges of imaging very small bodies and organs. Neonates also present with other unique physiological profile characteristics that must be taken under careful consideration. For instance, neonatal patients often have lower glomerular filtration rates, faster circulation rates, and faster pulmonary washing in and out of radioactive gases [32-33]. It is essential the imaging technologist take into careful consideration these factors when conducting an imaging study with a neonatal infant. Consultation with the equipment’s manual and manufacturer in order ensure that the device is optimized for use with pediatric or neonatal populations is strongly recommended. This will ensure that consistent and acceptable quality images are produced, while limiting the degree of radiation exposure.
One particular consideration for neonatal populations is the issue of portability. It is not uncommon for an infant to be placed in a Neonatal Intensive Care Unit (NICU) for several days following birth. Imaging of neonatal patients is generally conducted using portable neonatal radiography. In these cases, the infant’s crib may be very close to other infants in the NICU, placing these neighboring neonates at risk for exposure to scatter radiation . Neonates may also be encumbered with various tubes and other lines that can impede proper positioning of the infant during the imaging scans. Moreover, the infant may be left in the incubator for the portable radiography scan, which can impede proper positioning as well.
CT is also used among populations of neonates, particularly when conducting scans of the head. For instance, CT scans can be useful for follow-up assessments of hypoxia, intracranial trauma, and the presence of any hemorrhaging. CT is not commonly employed to image the abdomen or the pelvis in neonates. In some cases, IV contrast may be necessary in conjunction with CT imaging. Given that neonates are particularly sensitive to environmental contaminants, particularly those being held within the NICU, they may be placed at an augmented risk for allergic and nephrotoxic complications when administering these contrast agents.
The ideal imaging procedure for neonatal populations is US. In particular, this procedure is preferred as it does not require the use of ionizing radiation and thereby eliminates the risk for exposure to radiation. Moreover, the US device is practical and versatile, and it is quite portable. The US device is convenient for conducting imaging studies at the bedside of a critically ill neonate and should be regarded as the first choice when imaging very young infants.
Finally, while it is not considered the first line examination, MRI can be used as a follow up in order to clarify results from either US or CT assessments, due to its ability to produce detailed images of underlying tissue structures.
Diagnostic Imaging of Child Abuse
The primary role of imaging in cases of suspected child abuse is to identify the degree of the physical injury and elucidate any and all findings that may suggest alternative diagnoses . All diagnostic imaging studies exploring instances of suspected abuse must be evaluated for their risks and benefits.
While a musculoskeletal injury very rarely poses an immediate threat to the life of an abused child, these injuries are often the most significant radiological indicators of abuse. In fact, in an infant who is otherwise normal, specific patterns of injury can be sufficient to warrant a firm diagnosis of inflicted injury in the absence of clinical information . Skeletal survey imaging may be performed to assess skeletal fractures in various stages of the healing process and these findings can provide investigators with temporal information regarding the abuse, which may be key information in identifying the abuser.
In cases of suspected head trauma, CT without intravenous contrast should be employed, as this procedure has a high sensitivity and specificity for diagnosing acute intraparenchymal, subarachnoid, subdural, and epidural hemorrhage . CT can also assist in identifying facial fractures, skull fractures, or any associated soft tissue swelling.
In the case of suspected abuse, US is particularly useful in imaging the head through the anterior fontanelle in very young infants. Some types of subcortical white matter tears can also be identified via US.
Finally, MRI remains the ideal modality for providing a full assessment of intracranial injury, though there are a number of limitations with this technique in an acute-care setting. An MRI may be warranted following a CT in order to assess any areas of swelling or collection of cerebrospinal fluid.
When considering various imaging options for pediatric patients, physicians and other practioners must consider the appropriateness of imaging techniques that reduce or eliminate the possibility of exposure to ionizing radiation. Pediatric patients exhibit several unique considerations with regard to radiation safety, such that they are significantly more susceptible to ionizing radiation than adults. RTs should receive appropriate training on the risks and necessary procedures for further protecting this population from excessive radiation exposure. For instance, technologists must take extra precaution to ensure that the equipment is properly calibrated and adjusted to accommodate smaller patients. Should the technologist feel as though a particular referral for imaging is unnecessary, these concerns may be reported to the radiologist. In some instances, the technologist may even confirm the need for imaging with the ordering physician or practitioner.
This article outlined the most common imaging techniques applied to pediatric populations along with common indications. It is recommended that the technologist familiarize themselves with these common conditions affecting pediatric populations, in order to ensure their skill in executing the appropriate image capture for the diagnosis.
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