Viewing images on new devices
Are consumer, tablet and 6MP displays equally useful for detecting anatomical and pathological structures?
It depends on who is interpreting the images, research published in the July 2014 issue of Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology says.
With new technologies come potentially useful mobile devices and radiology applications. However, scientists in Finland could find only one study evaluating the effect of liquid-crystal displays on diagnostic performance of panoramic radiographs and none on tablet use.
Their aim, therefore, was to compare observer performance in detecting both anatomical and pathological structures in panoramic radiographs using consumer grade and tablet displays under suboptimal conditions as compared to the 6MP (megapixels) display calibrated with Gray Scale Standard Display Function under low ambient light conditions. Their research hypothesis was that medical display in low ambient light conditions is better than consumer grade display or tablet under high ambient light.
To investigate, the researchers selected 30 panoramic radiographs showing clearly visible structures. After an hour of training on how to use viewing programs, two observers with different levels of interpreting experience evaluated all images on each of the three display types.
Observer 1 was an oral and maxillofacial radiologist with eight years of experience. Observer 2 was a resident in oral and maxillofacial radiology with two years of interpreting experience. They evaluated images on the consumer grade display and the tablet during the first session and on the 6MP display three weeks later. They were each allowed one minute per image to evaluate seven different anatomical structures and pathological lesions from the left side of the jaw.
The observers used a five-point scaling system:
- definitely not a finding;
- probably not a finding;
- unable to evaluate;
- probably a finding;
- definitely a finding.
When successful ratings were tallied, researchers found that the less experienced observer performed significantly worse on a 30.4 inch tablet as compared to a 30.4 inch 6MP display in identifying dentinal caries in the lower molar and periapical lesions in the upper molar in panoramic radiographs under bright-light conditions. The more experienced observer performed similarly on the tablet and 6MP display.
In discussion, the researchers noted that other studies evaluating the accuracy of radiographic methods have shown significant differences in diagnostic performance between individual observers and have attributed this to differences in experience, training or visual perception.
“With regards to visual perception, in low lighting conditions the rods in the eye are activated and small differences in gray scale between pixels on the monitor can be seen. Conversely, at bright lighting levels, the rods are less active and small contrast differences are more difficult to observe,” the authors explained in discussion.
They cited previous supporting research. “To associate with differences in experience, training or visual perception, it seems that a more experienced radiologists sees more shades of gray.”
They concluded that a dentist in the early phases of training in interpreting panoramic images may be more dependent on a high-quality medical display used under optimal viewing conditions, while an experienced dentist can achieve high diagnostic standards using suboptimal diagnostic technology.
Consulting Editor: Laurie C. Carter, DDS, PhD
Past president, American Academy of
Oral and Maxillofacial Radiology
Reporting findings in a CBCT volume
Researchers advocating for a formal reporting system to help dentists review their cone-beam computed tomography volumes published a discussion of their reasoning in the July 2014 issue of Dental Clinics of North America.
“Reporting the findings in a CBCT volume is probably the most essential process in the total diagnostic evaluation of a patient, even if it is something as simple as implant planning,” the researchers said. With the article, authors aimed to help clinicians completely examine and report all findings, and to communicate precisely when referring and talking to patients.
They cautioned that dentists and dental specialists must examine all the data in the scan in a systematic and somewhat regimented fashion. Debate about the utility of a structured radiology report versus a narrative report continues even within the medical radiology community. Still, authors note that substantiation for a structured report to improve communication with colleagues and software applications is found in the literature. Also cited from previous research is the caution that failure to communicate clearly and effectively to a referring health care provider is one of the three most common reasons for malpractice suits.
One challenge outlined is that CBCT provides views with which dentists often are less familiar—such as the axial plane and anatomic regions including the cranial vault, the paranasal sinuses, the nasal cavity, the airway and the cervical spine.
Among their key points for adoption of a formal reporting system, authors observed, “The use of CBCT for dental treatment planning poses a situation in which the additional data in the acquired image volume that are outside of the scope of the primary dental concern could detect systemic conditions that possibly have a direct influence on the overall health and longevity of a patient.”
Authors include a list of radiographic changes observed within any of the paranasal sinuses that should raise suspicion and prompt referral.
Also included in the article are common findings CBCT enables in the nasal cavity, airway, cervical spine and temporomandibular joints.
An oral and maxillofacial radiologist, they note, usually is looking to uncover occult pathology that the referring dentist is not looking for because that is not the primary reason for the cone-beam examination.
“If dentists or nonradiologist dental specialists decide to examine their own volumes, however, then they are held to the same standard of care as an oral maxillofacial radiologist and [are] required to find and report any unusual conditions that may reside in that volume. This is a significant responsibility, one that might require additional training for some dentists.”
The authors collaborated with a cone-beam dental software company and recently released reporting software.
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Combining technologies to increase efficiencies
A case report published in the August 2014 issue of Implant Dentistry shows that by using a combination of CBCT and Optical 3-dimensional scanning, a clinician might bring the surgical and prosthetic phases of implant therapy together to enhance diagnostics and procedures.
The report centered on the treatment of a 74-year-old woman who visited the University of Detroit Mercy School of Dentistry for evaluation after noticing her fixed partial denture in the lower left mandible was moving. She reported that the prosthesis had been constructed some 25 years before.
The initial treatment plan included removing a failing implant in the region of tooth No. 18, followed by implant placement in the regions of numbers 18, 19 and 20 and removal of the mesially tilted No. 17. They predicted that their greatest challenge would be to avoid the remnant of an implant tip from the prior procedure in the No. 19 region.
The CBCT scan revealed that bone height around No. 19, at six millimeters, was compromised. The CBCT findings influenced a new approach to avoiding placement of implants that might impinge on the remnants of previous implants. The plan took advantage of all aspects of the technology, researchers said.
Their process included taking a CBCT scan of the jaw with an image aligner to help merge the CBCT data with the optical scan data. A 3D optical scan of the model (study cast) was generated and image data were stored.
Researchers merged data from both scanners and the study cast were aligned with the CBCT. Virtual planning, such as placement of teeth, implant position and creation of the drill guide were created with Implant Planning and Drill Guide software. Researchers sent the final treatment plan to the laboratory where 3D printing technology was used to fabricate a 3D model. They used the 3D model with the drill guide during surgical placement.
“We strongly believe that the level of success achieved combining these technologies is unsurpassed and could not have been achieved through free-hand implant placement,” authors said. They also noted in discussion that the advantage of this technique over virtual implant placement on the computer is that it brings the surgeon closer to the experience of placing the implant in the jaw than simulation on a computer can.
“By using the surgical model and drill guide during actual implant placement,” they wrote, “the implantologist was confident that all important neurovascular structures and elements of previous implant therapy were avoided, and significant postoperative morbidity eliminated.”
New research bodes well for tracking enamel loss
Research conducted by scientists at the University of Leeds, in England, yielded findings that may be promising for clinicians hoping to keep closer watch on erosive tooth surface loss (TSL) in their patients.
Appearance and function gradually diminish right along with the tooth enamel from cyclic acid attacks. Susceptible patients drink acidic beverages or have unusual drinking habits, such as swishing beverages around in their mouths. Also at risk, are those with conditions such as anorexia or gastroesophageal reflux disease (GERD). Since current clinical and laboratory techniques for monitoring erosive TSL have been deemed subjective, unreliable and expensive, a nondestructive measuring tool is increasingly in demand.
After considering previous research showing that ultrasound—a noninvasive imaging method—produced a reproducibility of 0.08 millimeters (mm), scientists publishing in the July 2014 issue of Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology designed a study for live teeth.
“The challenge in the case of erosive TSL measurements is not to make the individual measurement very accurate (knowing the exact remaining thickness of enamel) but rather to enable detection of change between visits so that the rate of erosive TSL can be determined. The key performance parameter in such cases is not accuracy (i.e., agreement with a gold standard) but rather reproducibility.”
To assess the reproducibility of enamel thickness measurements in vivo using an ultrasonographic system, the scientists recruited 30 volunteers. The enamel thickness of intact maxillary central incisors was measured with an ultrasonographic transducer during three separate visits, one week apart from each other. The researchers measured cervical, midbuccal and incisal sites.
The results showed “excellent precision (0.05 mm),” similar to the findings of previous in vitro research, revealing the use of ultrasound to measure enamel thickness highly reliable and reproducible in live teeth, authors said. The best location for making ultrasonographic measurements was the cervical site, followed by the midbuccal, outcomes showed.
Authors called for future work including refining the equipment to make it more user-friendly and clinically practical.
“This study is of great clinical significance in that it demonstrates for the first time in vivo that ultrasound is a reproducible, reliable and direct method with sufficient precision (0.05 mm) that can be used to quantify and serially monitor TSL.”
Incidental findings on CBCT images
With the frequency of incidental findings on CBCT reported at some 50 percent, further study is needed to understand the prevalence of significant discoveries and for guidance on identification overall, an editorial published in the May 2014 issue of Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology asserts.
According to the author, implications of the recognition and management of incidental findings, particularly those of indeterminate diagnosis, have received little attention in oral and maxillofacial (OMF) cone beam computed tomography imaging. Meanwhile, greater numbers of imaging studies, better resolution and practitioners’ increased knowledge are all factors contributing to a rise in their findings.
“It is clear that as the number of clinicians who own and operate CBCT equipment and interpret their own images continues to overshadow those with formal training in OMF radiology, guidance on recognition, interpretation and appropriate management of these findings is necessary,” the author said.
Among potential concerns, for example, are patient issues stemming from a range of professional opinions about reporting of incidental findings in medical radiography, which the author says are illustrative of the thoughts of OMF radiologists.
At one end of the spectrum is the concept that too much medical information is potentially harmful and that the patient would be better off not knowing all incidental findings, while others contend that practitioners have the ethical and legal duty to disclose all relevant medical information to patients.
In the absence of a consensus guideline, the author believes practitioners have a responsibility to develop individual management protocols to deal with unexpected findings and describes his own protocol, which involves three strategies.
Among the strategies is increased knowledge gained through means appropriate to the experience and training of the practitioner, such as familiarity with current scientific literature and attendance at continuing dental education courses on CBCT interpretation.
The author called for professional recommendations, with input from specific specialties and disciplines to develop clinical decision management algorithms and cited one recently published algorithm for the management of the incidental finding of calcified carotid artery aatheromata.
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‘Image Gently’ set to launch
Dental and other organizations worldwide, including the ADA, have lined up in support of Image Gently, a campaign sponsored by the Alliance for Radiation Safety in Pediatric Imaging (ARSPI) to spotlight issues related to the use of X-rays in children.
The campaign is set to launch Sept. 24 during the 65th Annual Session of the American Academy of Oral and Maxillofacial Radiology (AAOMR).
Dr. Gregory Zeller, associate dean for Clinical Affairs at the University of Kentucky College of Dentistry, is helping to promote the campaign, aimed at encouraging the safe use of oral and maxillofacial radiology in pediatric dental care.
The campaign, he said, is “designed to create awareness of the special issues involved in radiological imaging in children, provide educational materials and promote radiation protection for children.” The campaign’s target audiences, he said, are dental professionals, parents and the general public.
Watch for updates on the campaign as it unfolds.
ADA offers discount on ‘Digital X-Rays’ brochure
Now through Sept. 15, the ADA is offering members a patient education brochure on digital x-rays at a 15 percent discount.
Members can order “Digital X-Rays” (W522) through the ADA Catalog, using promo code 14360E. The 6-panel brochure is available in packets of 50 for $26; retail price is $3. Discounts also are available at higher quantities.
Written for the dental patient, the brochure notes that digital images are faster to create and send, and are more easily enlarged and enhanced. The brochure also tells patients how digital x-rays work and addresses questions about radiation safety. Patients also may appreciate that digital images are environmentally friendlier than conventional ones.
Members can preview this and other ADA brochures online at adacatalog.org. Orders can be placed online or by calling the ADA Member Service Center at 1-800-947-4746. Remember to use promo code 14360E to receive the 15 percent discount.
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What is Specialty Scan?
This is one in a series of quarterly newsletters updating dentists on selected specialties in dentistry. Information presented is aggregated and summarized from previously published materials, each item attributed to its publication of origin. This issue of JADA Specialty Scan focuses on oral and maxillofacial radiology, the third in the series on this topic for 2014. Other Specialty Scan issues are devoted to periodontics, orthodontics, endodontics and prosthodontics. The ADA has engaged the specialty organizations in these areas as well as its own divisions of Science and Legal to assist with these newsletters. We welcome your feedback on this and all Specialty Scan issues.
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