This article is intended to demystify the process for those with a potential interest in acquiring ultrasound skills. It is not intended to be a comprehensive review of head and neck ultrasound but, rather, is focused on the bare minimum requirements and considerations involved in clinician-performed ultrasound. The article covers the initial diagnosis and the unparalleled usefulness of ultrasound for surgical planning just before incision. Further readings are listed at the end of the article to direct the reader to some excellent texts to help build confidence and experience.
Key points
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Thyroid ultrasounds require initial training, validation, and establishment of competency.
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When selecting a clinic-based ultrasound, one should consider the important features and capabilities.
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The economics of an ultrasound purchase come down to what is achievable when it comes to medical billing.
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There are important ultrasound findings associated with thyroid malignancy.
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There is unparalleled usefulness for ultrasound in the operating room just before the incision.
Introduction
The role of ultrasound is widely acknowledged by radiology experts as the primary imaging modality for diseases of the thyroid. As its use has expanded and the technology has improved placing less-expensive, higher-resolution machines in the hands of nonradiologists, ultrasound has also created an important role for itself in the routine examination of cervical lymph nodes and head and neck masses outside of the central compartment. In the past decade, much has been written and much effort has been expended to increase the routine clinical use of ultrasound by head and neck surgeons. Beyond the initial diagnosis, the usefulness of ultrasound for surgical planning just before incision is unparalleled.
This article is not written to convince the reader that they should seek training in ultrasound, but it is intended to demystify the process for those with a potential interest. It does not aim to cover ultrasound findings in depth. Instead, it is focused on the bare minimum requirements and considerations involved in clinician-performed ultrasound. Further readings are listed at the end of the article to direct the reader to some excellent texts to help build confidence and experience. The topic of ultrasound-guided fine-needle aspiration (FNA) is addressed separately in another article by Orloff and colleagues in this issue.
Introduction
The role of ultrasound is widely acknowledged by radiology experts as the primary imaging modality for diseases of the thyroid. As its use has expanded and the technology has improved placing less-expensive, higher-resolution machines in the hands of nonradiologists, ultrasound has also created an important role for itself in the routine examination of cervical lymph nodes and head and neck masses outside of the central compartment. In the past decade, much has been written and much effort has been expended to increase the routine clinical use of ultrasound by head and neck surgeons. Beyond the initial diagnosis, the usefulness of ultrasound for surgical planning just before incision is unparalleled.
This article is not written to convince the reader that they should seek training in ultrasound, but it is intended to demystify the process for those with a potential interest. It does not aim to cover ultrasound findings in depth. Instead, it is focused on the bare minimum requirements and considerations involved in clinician-performed ultrasound. Further readings are listed at the end of the article to direct the reader to some excellent texts to help build confidence and experience. The topic of ultrasound-guided fine-needle aspiration (FNA) is addressed separately in another article by Orloff and colleagues in this issue.
Initial ultrasound training
At the current time in the United States, training of nonradiologist specialists in ultrasound presents a bit of a conundrum. It has been an integrated part of obstetrics and gynecology residency programs for well more than a decade. More recently, the use of ultrasound in trauma evaluations, such as the Focused Assessment with Sonography for Trauma examination, has been part of formalized residency training for general surgeons and emergency medical specialists. For most specialists, notably otolaryngologists interested in general neck examination applications and others interested in endocrine applications specifically, the formal training has been much more limited. Sponsored training programs in the United States have been primarily in the form of introductory postgraduate courses.
With respect to thyroid and parathyroid applications, there are now 3 organizations within the United States offering postgraduate training programs: the American Association of Clinical Endocrinologists (AACE, www.aace.org ), the American College of Surgeons ( www.facs.org ), and the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS, www.entnet.org ). These organizations offer 1- and 2-day postgraduate courses aimed at introducing the practicing clinician to the basics of ultrasound. The courses include a precourse preparation package and at least a half day of didactics covering ultrasound physics, basic instrumentation (also known as knobology), basic image interpretation, and clinical applications (for an example, see Ref. ). The second half of a 1-day course is spent in a hands-on practice session. The culmination of the course is a practical examination and the awarding of a certificate from the sponsoring group.
The practical issue remains as follows: What does a 1- or 2-day course actually prepare the clinician for? At best, these courses are a cursory introduction to ultrasound techniques; this single fact has led to a general discounting of their worth by medical insurers among others and used as a justification to deny payment for services such as image-guided FNA. It is generally agreed that the best way to train nonradiologist clinicians in ultrasound techniques is by integrating the training into the respective residency training programs (eg, the American Board of Otolaryngology, www.aboto.org ). Efforts to do so are currently ongoing, but such an approach clearly leaves out most of the practicing specialty clinicians for the next decade or so unless there is a mechanism to fully train and assess competency among clinicians within a postgraduate setting.
Obtaining adequate experience: validation and assessment of competency
At the present time, there is no formal validation process for head and neck surgeons to further their ultrasound training beyond the initial course, though there are active initiatives to institute one. Through the auspices of the AACE, endocrinologists have been several years ahead of head and neck surgeons in actively supporting postgraduate ultrasound education. A relationship between the AACE and the American Institute for Ultrasound Medicine (AIUM, www.aium.org ) has led to the creation of a voluntary peer-review process, the AIUM Ultrasound Practice Accreditation program. This program includes a formal mechanism for submitting cases for review leading to initial accreditation and includes a requirement for reaccreditation every 3 years. This type of program meets the requirements of many insurance organizations and holds the promise of increased standardization leading to better outcomes.
At the conclusion of the 1- and 2-day courses, attendees are instructed to seek a mentorship with an experienced colleague, a radiologist, or radiology department performing head and neck ultrasound. Ongoing self-evaluation and feedback can be an important part of continuously honing skills and as part of a recurrent training process. An example of this is an almost-daily exercise the author avails himself of in his clinical practice. When performing a focused portable ultrasound examination in the clinic as part of a full head and neck examination in preparation for a FNA, the portable examination findings are compared with the more complete formal ultrasound examination obtained in the radiology department’s ultrasound suite. The reader should rightly ask the following: How confident can the neophyte nonradiologist ultrasonographer be in this type of training process, and how much experience is necessary to obtain a satisfactory level of competence?
Defining competency is one of the central issues in all of medical education. Residency education within the United States has recently been completely reengineered around the assessment of core competencies. Under the older system, surgically oriented resident educational progress was assessed principally by the number of procedures performed as an assistant and as a primary surgeon. Under the new system, the number of procedures is still tracked, but the emphasis is placed on the continuous evaluation of a set of skills. For nonradiologist specialty ultrasound training, self-assessment with the help of a mentor is the currently touted mechanism. Seen from the vantage point of core competencies, is this a viable training methodology, and can adequate competency be achieved under these conditions?
To help answer the questions, it is instructive to look at the current training for sonographers and radiology residents (sonologists) in the United States and Canada as a point of comparison. Sonographers are the technicians who perform most of the ultrasound examinations. The American Institute for Ultrasound in Medicine (AIUM, www.aium.org ) publishes the accreditation standards in the United States, and the Canadian Society of Diagnostic Medical Sonographers ( www.csdms.org ) publishes them in Canada. When it comes to actually performing the ultrasound examinations, their training is the most extensive and includes 300 to 500 procedures performed over a 2- to 3-year period. In contrast, radiologists, accredited by the American College of Radiology ( www.acr.org ) in the United States and by the Royal College of Physicians and Surgeons of Canada ( www.royalcollege.ca ), spend approximately 6 months of their residencies in dedicated ultrasound interpretation training.
These gold standards of training are extensive and comprehensive; but when broken down into the different body areas, the time spent on any single area, such as the head and neck region, is much more approachable for nonradiologist specialists. Obstetrics and gynecology ultrasound is arguably the largest ultrasound segment in radiology residencies. Seventy-five percent of radiology residents spend less than 4 weeks per year over a 2-year period obtaining experience in this area. What is particularly interesting is that 30% of their experience is obtained outside of the radiology department and 40% is estimated to occur after hours without an attending present at the time of the examination. In effect, much of the ultrasound training occurs through examination comparison with a mentor, which is precisely the same situation that nonradiologist specialists are faced with when seeking validation and assessment of competency.
As for the issue of how many examinations are required to achieve an acceptable level of competency, several studies of the learning curve in ultrasound examination have established that an average of 25 to 50 focused examinations are needed to achieve greater than 90% concordance with a radiologist’s interpretation of the same examination. A recent article addressed the specific issue of observer experience (<2 years or >7 years) and evaluation of thyroid malignancy and lymph node metastases in 1421 patients. Preoperative staging included extrathyroidal extension and ultrasound features of lymph node metastases, including shape, echogenicity, microcalcifications, cystic change, and vascularity. The two groups differed only in their ability to assess lateral neck compartment lymph node involvement (38.5% predictive for the <2-year group compared with 64% in the >7-year group).
Comparisons with radiologists may not answer all questions when it comes to competence. Studies have raised issues regarding the level of training for radiology residents and whether it is adequate in ultrasound. The reasons for the lack of competence among radiologists present an interesting counterpart to the discussion of nonradiologist competence. One of the main problems for the radiologists in the study was the lack of detailed anatomic knowledge and the inability of 44% to identify anatomic landmarks. Considering the detailed anatomic knowledge of the head and neck region possessed by the average head and neck surgeon and the attainment of comparative competency in the focused ultrasound examination studies, an outside observer could easily conclude that achievement of competence in head and neck ultrasounds is well within the means of the average head and neck surgeon.
Essential equipment and the economics of clinic-based ultrasound
The past 5 years has seen a substantial change in the ultrasound marketplace and the pricing of portable ultrasound units. Major companies envisioned the original market for ultrasound as being limited to the radiologic suite. The significant increase in ultrasound-trained nonradiologist specialists has created a burgeoning market for more portable ultrasound units for use in obstetrics-gynecology, urology, otolaryngology, general surgery, orthopedics, neurosurgery, cardiology, vascular surgery, and emergency medicine, among others. The analytic electronics contained in the portable units are largely equivalent to those found in the larger radiologic suite units. The main differences are found in storage capacity, probe capability, and postimaging analysis.
Portable units are available from many manufacturers along with optional equipment, such as dedicated carts that can contribute substantially to the cost. Fig. 1 is a real-world photograph of a unit the author uses routinely in an otolaryngology clinic setting. The essential elements are all evident in the photograph: a generic clinic cart with a drawer, a portable ultrasound unit, one linear multifrequency probe used for small-parts examinations, probe gel, saran wrap, and rubber bands (located in the drawer) for protecting the probe from blood during FNA. Units with more capability than the one in the picture are widely available for approximately $20,000 at the time of this writing.
Picking an ultrasound is a personal decision, and the reader is to be encouraged to try different units before purchasing. That being said, the ergonomics of the most common units are comparable and allow for increasingly easy transitions between units available throughout a hospital. There are literally hundreds of specifications and options listed in ultrasound brochures. The basic capabilities of a useful unit for head and neck examinations should include the following:
Monitor
High-resolution color LCD, diagonal dimension: 15 in, resolution: 1024 × 768.
Imaging Modes
B, color Doppler, power Doppler, duplex mode for B/Doppler, spatial compounding imaging for linear probes (desirable).
Cineloop Capabilities
Support for B, color Doppler, and power Doppler. The potential length/time of a cineloop depends on the maximum frame storage (>1000 frames is desirable) as well as the frame rate (see later discussion).
Transducer
A single, linear array, multifrequency probe for small parts. The most useful range of frequencies is 7.5 to 12.5 MHz for neck structures. Higher-frequency small-parts probes up to 15 MHz are becoming increasingly available and affordable. There are theoretical advantages to the higher frequencies when it comes to parathyroid localization. (See “Further readings” for more details and a discussion of ultrasound physics.)
Output Modalities
USB, Ethernet, S-video/VGA/composite video (can be achievable through USB adapters).
Peripherals
USB-connected storage unit and/or DVD recorder, programmable pedal footswitch (desirable) (The use of a footswitch can make FNA image capture significantly easier.)
Display Dynamic Range
100 dB (B mode).
Frame Rate
Approximately greater than 350 frames per second (varies with transducer in use as well as processing capabilities).
Bottom line on technical specifications
Additional technical specifications, such as processor speed, memory, and storage, all affect the capabilities of the unit; but beyond the basic specifications listed earlier, the comparison of individual technical specifications does not necessarily add significantly to the process of selecting a machine. Many times, it is easier to compare the general capabilities and the user experiences as surrogates for the underlying electronics.
Image documentation for medical billing
Image documentation is frequently necessary for the medical record and is required for medical billing purposes (see article by Orloff and colleagues in this issue). A programmable footswitch makes the process much easier for image recording as well as for unit adjustment during examinations performed by a solo clinician. The economics of an ultrasound purchase comes down to what is achievable when it comes to medical billing. In 2013, billing for clinical ultrasound in the United States involves 2 Current Procedural Terminology (CPT) code groups: 76536 and 76942/10022 ( Table 1 ). The diagnostic code 76536 poses the greatest difficulty for the nonradiologist to achieve reimbursement with for understandable reasons. More rigorous proof of validation and competency through formalized accreditation mechanisms as mentioned earlier (eg, AIUM Ultrasound Practice Accreditation) should go a long way to easing this situation for the physician with postgraduate training. The incorporation of formal ultrasound training into residencies, such as obstetrics and gynecology, led to the recognition of ultrasound being part of the specialty’s area of competence.
