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 Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 2  |  Issue : 3  |  Page : 82-87

Effectiveness of 18 F-sodium fluoride positron emission tomography/computed tomography scan in the early detection of periradicular lesions


1 Department of Dentistry, Faculty of Odontology, Universidade de São Paulo, São Paulo, Brazil
2 Departament of Nuclear Medicine, Hospital Israelita Albert Einstein, São Paulo, Brazil
3 Department of Endodontics, CETAO, São Paulo, Brazil

Date of Web Publication14-Nov-2014

Correspondence Address:
Ana Laura Pion de Carvalho
R. Monte Alegre, 212 cj 92, São Paulo, SP
Brazil
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2321-3841.144678

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  Abstract 

Objective: Establishing the correct diagnosis is key for the implementation of adequate therapy. The aim of this study was to analyze the sensitivity of 18 F-sodium fluoride positron emission tomography/computed tomography (PET/CT), in comparison with conventional radiographic imaging techniques (periapical/parallelism technique and panoramic radiographs), in the early detection of periradicular lesions. Materials and Methods: A total of 256 maxillary and mandibular areas from eight patients were randomly selected for analysis using conventional radiographic techniques and PET/CT. The nuclear image acquisition protocol included scans from the top of the head to the middle third of the neck region. After analysis of the images obtained with different methods (periapical vs. panoramic radiography, and radiography vs. PET/CT). The number of images with positive findings for infection were compared using ANOVA (P ≤ 0.05). Results: There were no significant differences in the number of positive images between the two conventional radiographic techniques: Six (2.34% of the sample) and seven (2.73%) positive images were found among panoramic and periapical radiographs, respectively. Conversely, PET/CT yielded 39 (15.23% of the sample) images positive for infection, significantly higher number when compared with the two conventional radiographic techniques assessed. Conclusion: Positron emission tomography/computed tomography showed to be more effective than conventional radiography in the early detection of dental infection. These findings allow to suggest that the use of PET/CT in endodontics would significantly contribute to the early and accurate diagnosis of periradicular lesions.

Keywords: Computed tomography, diagnosis, endodontics, 18 F-sodium fluoride, positron emission tomography


How to cite this article:
de Carvalho AL, Yamaga LI, Nogueira SA, Wagner J, Gavini G, Davidowicz H. Effectiveness of 18 F-sodium fluoride positron emission tomography/computed tomography scan in the early detection of periradicular lesions . J Oral Maxillofac Radiol 2014;2:82-7

How to cite this URL:
de Carvalho AL, Yamaga LI, Nogueira SA, Wagner J, Gavini G, Davidowicz H. Effectiveness of 18 F-sodium fluoride positron emission tomography/computed tomography scan in the early detection of periradicular lesions . J Oral Maxillofac Radiol [serial online] 2014 [cited 2019 Jun 17];2:82-7. Available from: http://www.joomr.org/text.asp?2014/2/3/82/144678


  Introduction Top


Establishment of a correct diagnosis is crucial for the institution of adequate therapy. However, the diagnosis of pulpal, periapical, and periodontal conditions sometimes lacks precision, especially because their analysis is based on the use of various clinical and image resources. [1] Several authors have reported that the detection of periradicular lesions based on dental imaging techniques routinely used in clinical practice (namely, radiography) occurs only at a late or advanced stage of infection. [2],[3],[4] This limitation causes delays in treatment initiation and consequently worsens the severity of tissue damage, leading to a less favorable prognosis.

Recent advances in diagnostic imaging techniques have allowed a more detailed analysis and provided increased sensitivity for the detection of periradicular lesions. [5] Practitioners now have the possibility to complement routine radiographic examinations with a new generation of imaging techniques, thus being able to obtain a more accurate diagnosis and reliable description of the metabolic and structural characteristics of periradicular lesions. [6]

Positron emission tomography/computed tomography (PET/CT) is a nuclear medicine technique in which a radioactive tracer is administered to the patient and collects in a given organ or tissue, remaining there for a long enough time period to allow detection by specific equipment that produces tracer distribution images. [7] PET scanners can be used alone or in association with conventional CT scanners (then named multi-slice spiral scanners), allowing morphological (CT) and metabolic (PET) images to be simultaneously obtained.

Different imaging agents have been used with PET/CT, including fluorine-18 fluoromisonidazole and fluordeoxiglicose. [6],[8] In our study, we decided to use 18 F-sodium fluoride ( 18 F-NaF) as the imaging agent because of its high and rapid bone uptake. [7]

The objective of this study was to compare diagnostic data obtained with 18 F-NaF PET/CT and conventional radiographic imaging techniques (periapical/parallelism technique and panoramic radiographs) in the detection of periradicular lesions.


  Materials and Methods Top


The study protocol was approved by the Research Ethics Committee of the institution where the study was carried out (protocol no. 041/10 CEP/ICS/Universidade Paulista).

A total of 256 maxillary and mandibular areas (1 area/tooth) of eight patients (four males and four females) schedule for the PET/CT exam were selected for analysis. Patient age ranged from 27 to 48 years.

After anamnesis and clinical examination, patients were submitted to radiographic examination as follows: Panoramic radiographs (HF100 X-ray machine, 70 kV, Dabi Atlante, Ribeirão Preto, Brazil) and periapical radiographs (Dabi Spectro 70× Eletronic, 70 kV, Ribeirão Preto, Brazil) using the paralleling technique. Insight radiographic films were used (Eastman Kodak Co., Rochester, USA) combined with Hanshin intraoral film-holders (Jon, São Paulo, Brazil) and a lead apron for gonadal and thyroid protection.

[Table 1] shows the verification of image and clinical findings, describing positive and negative findings in each patient.
Table 1: Number of areas with images suggestive of periradicular lesions in each patient, according to different imaging methods

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Subsequently, patients were also submitted to 18 F-NaF PET/CT (Discovery ST, GE Medical Systems, Milwaukee, WI, USA). All patients signed an informed consent form prior to administration of the imaging agent and inclusion in the study.

18 F-NaF PET/CT image acquisition was performed at the Service of Nuclear Medicine at Hospital Israelita Albert Einstein, São Paulo, Brazil. First, 18 F-NaF was administered intravenously at a dose of 370 MBq (dose calculated based on the weight of an adult, approximately 70 kg). Images were collected 30 min after tracer administration. The protocol included images from the top of the head to the middle third of the neck region, with the patient lying in the supine position and the arms resting at the sides. CT section thickness was 1.25 mm. Patients were immobilized using a head support specifically designed to prevent movement of the area under analysis and consequently image distortion. In order to maintain an uniform parallel position between maxillary and mandibular arches, patients were instructed to hold an insulin/hypodermic syringe with their anterior teeth (Injecta, Belo Horizonte, Brazil).

All PET/CT images were analyzed by one nuclear physician and one endodontist with expertise in the method. All images showing hot spots in the dental areas selected for analysis were considered to be positive. Possible inflammatory/infectious disease processes were quantified using the standard uptake value as a semiquantitative criterion.

Following image analysis, results were statistically analyzed and expressed as absolute numbers and percentages of positive images. The number of positive images obtained with each of the three methods (periapical vs. panoramic radiography, and radiography vs. PET/CT) was compared using ANOVA (P ≤ 0.05).


  Results Top


[Table 2] shows the results obtained with the maxillary and mandibular areas analyzed in relation to the presence of images suggestive of periradicular lesions. The number of positive findings obtained with PET/CT was significantly higher when compared with the two radiographic methods assessed (ANOVA, P = 0.05). In turn, no significant differences were observed between the two radiographic imaging techniques employed (panoramic and periapical) [Table 1] and [Table 3].
Table 2: Areas suggestive of periradicular lesions according to the different imaging techniques employed

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Table 3: Number of areas with images suggestive of periradicular lesions in each patient, according to different imaging methods

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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5] shows image suggestive of periradicular lesions in patient number 6. Subsequent clinical examination of the teeth confirmed the presence of two periradicular lesions caused by residual roots in the maxilla and caries in the distal surface of the lower left first molar.
Figure 1: Panoramic radiograph showing areas associated with hot spots on positron emission tomography/computed tomography (arrows)

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Figure 2: Periapical radiograph (paralleling technique) showing areas associated with hot spots on positron emission tomography/computed tomography

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Figure 3: (a) Positron emission tomography (PET) image; (b) computed tomography (CT) image; (c) integrated PET/CT image, showing hot spots on teeth no. 14, 15, and 16

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Figure 4: (a) Positron emission tomography (PET) image; (b) computed tomography (CT) image; (c) integrated PET/CT image, showing hot spots on tooth no. 14

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Figure 5: (a) Positron emission tomography (PET) image; (b) computed tomography (CT) image; (c) integrated PET/CT image, showing hot spots on teeth no. 14 and 24

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  Discussion Top


Accurate diagnosis of dental conditions in general and of endodontic conditions in particular requires the greatest possible amount of data available, collected during clinical examination like the thermical, electrical, percussion and palpation tests or via supplementary tests following anamnesis. Once all signs and symptoms have been identified and analyzed, it will be possible to determine the most adequate therapy for the condition found in each case.

In spite of all technical innovations recently seen in radiology, the radiographic detection of periapical and periodontal lesions is only possible, still today, at an advanced stage of infection. [9] This can be explained by the following limitations of radiography:

  1. Low sensitivity, which requires a high degree of tissue damage for lesion detection;
  2. Low level of structural detail offered by two-dimensional imaging methods in the analysis of mineralized tissues; and
  3. Radiographic underestimation of loss of bone tissue when compared with data collected clinically.


In this sense, the recent introduction of tomographic technologies into the dental clinical practice has largely improved image analysis in terms of details and the early detection of lesions. [2] Moreover, the contribution of more accurate diagnostic imaging techniques has been especially important in cancer patients submitted to chemotherapy or radiotherapy, or in patients with other systemic conditions, once they can guarantee the total absence of infectious disease processes in the oral cavity, improving prognosis of the underlying disease. [10]

Braz et al.[11] and Fonse Ca et al.[12] have recommended the use of CT (rather than two-dimensional radiographic techniques) for three-dimensional analysis of the human pulp-dentin complex and other structures of the oral cavity. However, CT techniques are also dependent on static exams, which require changes to the tooth structure for the detection of abnormalities. Hence, although radiography is an easy-access, routine diagnostic tool in dental clinical practice, and although the use of CT has improved image analysis, both techniques present limitations that have motivated dental practitioners to seek complementary resources for each specific case.

With the aim of obtaining early data on endodontic periapical lesions (as early as possible in the course of the disease), Davidowicz et al.[13] have compared diagnostic information on periapical abnormalities provided by scintigraphy and radiography. In that study, scintigraphy showed hot spots in areas considered to be normal on radiographs, but failed to locate the lesions precisely. In 2002, Faltin et al.[14] created a device that allowed the exact location of a hot spot to be determined, thus overcoming this limitation of the scintigraphic method. Since then, scintigraphic mapping has become extremely important tool in the so-called dynamic diagnostic imaging field and endodontic diagnosis, especially in conditions such as postendodontic periapical lesions, ghost pain, fractures, early periapical reactions, among others.

The present study was conducted to assess the diagnostic information provided by another state-of-the-art imaging technology, namely hybrid PET/CT, in the detection of metabolic abnormalities of the alveolar bone. In our study, the imaging agent 18 F-NaF was selected based on its high bone uptake, as previously described by Grant et al. [15] and Laverick et al. [16] Overall, the method provided reliable diagnostic information on periapical lesions.

Some of the areas identified as hot spots on PET/CT in our sample were found not to be periradicular lesions. This occurred most frequently in patients presenting with sinusopathy or third molar eruption. These findings suggest that sinusopathies should be considered a contraindication for PET/CT, as also recommended by Davidowicz et al., [13] Faltin et al. [14] Shimamoto et al., [6] and Laverick et al. [16] Eruption processes detected with PET/CT imaging, in turn, should be confirmed radiographically to assess the phase of the eruption, as also recommended by Davidowicz et al. [13] and Wild et al.[17] Nevertheless, the visualization of these processes/conditions as hot spots on PET/CT is indeed a limitation of this method and underscores the need to carefully interpret the results of new, complementary technologies.

In some cases where radiographs failed to detect the presence of mineralized tissue damage, the PET/CT method showed hot spots in the periapical region. These PET/CT findings were confirmed at the subsequent clinical examination, which included pulp vitality and percussion tests to allow diagnosis of necrotic and/or inflammatory processes. Of the 256 teeth assessed, 17 were diagnosed with necrotic pulps after comparison of clinical, radiographic, and PET/CT findings and were referred for endodontic treatment. This decision was made based on the studies of Shimamoto et al.,[6] Laverick et al., [16] and Wild et al. [17] Five other teeth were extracted due to the impossibility of performing endodontic treatment.

Still within the same perspective, it is possible to infer that pulpal inflammation is not always restricted to the pulp, potentially implicating circulatory abnormalities affecting the periapical region, which tend to be associated with resorption processes that cannot be detected with radiography. These findings are also compatible with the reports of Davidowicz et al., [13] Faltin et al. [14] and Shimamoto et al. [6]

It's known that in spite of being a method that shows an early diagnosis, PET/CT present some limitations like the image artifact due to motion and dental filling. In addition, the cost of the exam is high when compared with a planar bone imaging, the radiation exposure is 68% greater when 18 F sodium fluoride (0.024 mSv/MBq) is used compared with 99m-Tc-methylene diphosphonate (0.0057 mSv/MBq), patients discomfort during injection and imaging due to the need to be motionless.

Regarding to a practicality in the out-patient setting needs, it should be considered that those exams would be done in patients that will pass through immunosuppressive therapies, because those patients must not have any kind of infection in their organisms. According to Brenner et al. [18] in the USA, the National Outpatient PET registry recently is gathering data on the right use of 18 F sodium fluoride, only to use it in tumor cases. It provides coverage with evidence development, with the goal of assessing the impact of the 18 F sodium fluoride PET on intended management, treatment intent, quality of life, and survival, comparing pre-PET intended management versus actual management after PET.

The results presented in [Table 1] and [Table 3] reveal that the number of images suggestive of abnormalities affecting the alveolar bone was statistically higher with PET/CT (39) than with periapical radiographs (seven) or with panoramic radiographs (six), which is in agreement with the findings reported by Shimamoto et al. [6] and Laverick et al. [16] Conversely, no significant differences were observed between panoramic and periapical radiographs, probably as a result of the refinement observed along recent years in the field of radiography as a whole. Different results have been reported by Davidowicz et al. [13] and Shimamoto et al. [6]

In summary, this study is able to conclude that PET/CT is an effective alternative imaging method for use in dental clinical practice, capable of providing useful complementary information for the diagnosis of different conditions that cannot be adequately described using routine diagnostic tools. Radiography is undoubtedly an important clinical tool, and in fact radiography and PET/CT provide complementary diagnostic information. Further research is necessary to assess other potential contributions of PET/CT to the dental clinical practice, possibly leading to the consolidation of this method as a dental diagnostic tool.

 
  References Top

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Jorge EG, Tanomaru-Filho M, Gonçalves M, Tanomaru JM. Detection of periapical lesion development by conventional radiography or computed tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:e56-61.  Back to cited text no. 3
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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