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 Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 27  |  Issue : 4  |  Page : 520-526

Comparison of diagnostic accuracy of conventional radiography, digital radiography, and ultrasound imaging in the detection of periapical lesions


1 Department of Oral Medicine and Radiology, Swami Devi Dyal Hospital and Dental College, Barwala, Haryana, India
2 Department of Conservative Dentistry and Endodontics, Swami Devi Dyal Hospital and Dental College, Barwala, Haryana, India
3 Department of Conservative Dentistry and Endodontics, Government Dental College, Srinagar, Jammu and Kashmir, India
4 Department of Oral Medicine and Radiology, SVS Institute of Dental Sciences, Mahbubnagar, Telangana, India
5 Department of Pedodontics and Preventive Dentistry, KD Dental College, Mathura, Uttar Pradesh, India

Date of Submission19-Apr-2015
Date of Acceptance18-May-2016
Date of Web Publication19-Aug-2016

Correspondence Address:
Dr. Aravinda Konidena
Department of Oral Medicine and Radiology, Swami Devi Dyal Hospital and Dental College, Barwala, Haryana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-1363.188719

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   Abstract 

Introduction: Accurate diagnosis of periapical lesions may be necessary not only to predict the treatment outcome but also to decrease the incidence of root canal treatment failure. Ultrasound imaging is an easy, reproducible technique, which is based on the evaluation of reflected echoes and has the potential to differentiate the periapical lesions. Aim: To compare the diagnostic accuracy of conventional radiography, digital radiography, and ultrasound imaging in the detection of periapical lesions. Materials and Methods: Thirty patients aged between 20 and 40 years, presenting with well-defined periapical radiolucencies in relation to anterior maxillary or mandibular teeth, indicated for extraction or periapical surgery were subjected to conventional and digital radiographic examination by paralleling technique followed by ultrasonological examination. Three observers (A, B, C) gave their radiographic diagnosis twice at an interval of 2 weeks. A sonologist assessed the size, contents, echogenicity and vascular content of the lesions. The diagnosis was compared with histopathological examination of tissues obtained by extraction or periapical surgery. Results: The diagnostic accuracy of ultrasound imaging was 83.33%, which was higher than conventional radiographic examination by all observers (53.33-76.66%) and digital radiographs by observers A and B (70-80%). Conclusion: Our study revealed that ultrasound with color Doppler was an efficient tool for diagnosing periapical lesions as it had better diagnostic accuracy than conventional and digital radiography.

Keywords: Conventional radiography, digital radiography, periapical lesions, ultrasound imaging


How to cite this article:
Bansal TK, Konidena A, Bansal R, Khursheed I, Reddy J, Khursheed O. Comparison of diagnostic accuracy of conventional radiography, digital radiography, and ultrasound imaging in the detection of periapical lesions. J Indian Acad Oral Med Radiol 2015;27:520-6

How to cite this URL:
Bansal TK, Konidena A, Bansal R, Khursheed I, Reddy J, Khursheed O. Comparison of diagnostic accuracy of conventional radiography, digital radiography, and ultrasound imaging in the detection of periapical lesions. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2021 Jul 26];27:520-6. Available from: https://www.jiaomr.in/text.asp?2015/27/4/520/188719


   Introduction Top


Conventional radiography traditionally forms an indispensable adjunct in oral diagnosis, treatment planning, and follow-up of periapical lesions. [1] The commonly encountered periapical lesions following dental caries or trauma are periapical abscess, periapical granuloma, or periapical cyst. Accurate diagnosis of periapical lesions may aid not only in predicting the treatment outcome but also may decrease the incidence of root canal treatment failure associated with lack of an appropriate diagnosis. [2]

Conventional radiography provides a two-dimensional image of a three-dimensional structure, thus may fail to differentiate a small periapical cyst from a large periapical granuloma, since the major defining parameter taken into consideration is the size of the lesion along with the presence of sclerotic border. [3],[4] The chances of accurately interpreting periapical lesions on the basis of appearance on conventional radiography are hence poor enough to warrant dependence on this method. [2] Accurate diagnosis by gold standard histopathology [3] may not be possible at the right juncture or the decisive moment in all cases, thus defeating the ulterior motive of an ideal diagnostic modality and making it impractical for non-surgical cases.

Due to the limitations of conventional radiography and histopathology, search for the identification of a more promising modality for an early and accurate diagnosis of periapical lesions continued. Digital imaging has gained popularity due to its reduction in patient exposure, ability to manipulate the image, enhance and analyze it, thus making it appealing. [5],[6] However, studies have shown that direct digital radiography even with image processing and enhancement is no better than conventional radiography in the diagnostic accuracy of periapical lesions. [7]

Ultrasound imaging is an easy and reproducible technique that has the potential to supplement conventional or digital radiography in the diagnosis of periapical lesions. Ultrasound evaluates the reflected echoes from the interface between different tissues based on their acoustic properties and thus may differentiate between cysts and granulomas due to the differences in content. The ability of ultrasonography (USG) to describe the contents and vascularization of the lesion outline an important factor while diagnosing periapical lesions. [3],[8] These uncertainties prompted us to compare the usefulness and diagnostic validity of three imaging modalities in the evaluation of periapical lesions by comparing them with gold standard diagnosis of histopathology.


   Materials and Methods Top


Ethical clearance

The study protocol was approved by the institutional ethical committee and informed consent was taken from all participants prior to their recruitment as study subjects.

Selection and description of participants

A total of 30 patients, aged between 20 and 40 years, presenting with well-defined periapical radiolucencies in relation to anterior maxillary or mandibular teeth, diagnosed by clinical signs and radiological findings, and who were indicated for extraction or periapical surgery were selected for the study. Radiographic lesions caused by systemic conditions (hyperparathyroidism, Paget's disease, fibrous dysplasia, multiple myeloma, osteoporosis), endo-perio lesions, or ill-defined radiolucencies and endodontically/orthodontically treated patients were excluded from the study. The study participants were then subjected to complete history taking and clinical examination, followed by direct digital radiography and ultrasonography. The participants were donned lead aprons and thyroid collars prior to the radiologic examination and adequate radiation protection measures were adopted.

Technical information

Conventional radiography

A pre-operative intraoral periapical (IOPA) radiograph was taken for all the patients at the region of interest by paralleling technique using a film holder with external aiming device. The intraoral X-ray unit Toshiba DG/073B (Satelec, 2.5 mm Al total filtration, focus 0.7 mm) and Kodak E-speed (Eastman Kodak Co., France) of film size 2 (31 × 41 mm) were used. The exposure parameters used were 70 kVp, 8 mA, and 0.25 s. The exposed radiographs were processed using a fully automatic intraoral processor (Velopex Intra X Automatic Developer; Velopex International, London, UK) under optimal processing conditions, as described by the manufacturer.

Three observers (two oral radiologists and one endodontist) were asked to make a detailed description of the periapical lesions in the films mounted on a uniformly illuminated view box under ambient viewing conditions, including the size, content, and borders, and provide radiological diagnosis. The dimensions of all the lesions were measured in superoinferior (SI) and mesiodistal (MD) directions using a divider and a ruler on a millimeter scale. The measurements were repeated after 2 weeks.

Digital radiographic examination

The patients were subjected to digital radiographic examination by paralleling technique with RVG Kodak 5000 (Kodak-Trophy for Eastman Kodak Company, France) with an intraoral sensor size 2 (43 × 33 mm). RVG Kodak 5000-X va3 software was used for image manipulation and Samtron 56 V monitor for visualization of image. The exposure parameters used were 70 kVp, 8 mA, and 0.04 s. The digital images were first presented as original images to the three observers independently, following which they were allowed to use different image processing facilities provided by the software of the system. Using a scale installed in RVG Kodak 5000 software, the size of the lesions was measured in SI and MD directions by the three observers.

Ultrasonological examination

All the lesions were examined sonologically by a sonologist using diagnostic ultrasound machine Toshiba, Nemio-20 (GE Medical System, San Francisco, USA) with color Doppler, incorporating a high-definition, multifrequency, 32 mm linear array ultrasonic probe (PLM-703AT) operating at a frequency of 6-11 MHz. The ultrasound probe was coated with a layer of ultrasound gel and positioned on the skin covering the radicular area of the tooth of interest. After the identification of the defect, the probe was moved around the area several times in different positions to obtain an adequate number of transverse scans in the axial plane and longitudinal scans in the sagittal plane. The dimensions of all lesions were measured in three planes, i.e. anteroposterior, SI, and MD, and recorded. Color Doppler was applied to detect the blood flow in the lesion. The images were assessed for the size and content (fluids, solids, or a combination of both). According to the echogenicity and other relevant features, the pathosis was delineated according to the following criteria. [9]

Cystic lesion

Hypoechoic well-contoured cavity surrounded by reinforced bone walls filled with fluid and with no evidence of internal vascularization on color Doppler examination.

Granuloma

Poorly defined hypoechoic area showing rich vascular supply on color Doppler examination.

Mixed lesion

Predominately a hypoechoic area with focal anechoic area, showing vascularity in some areas on color Doppler examination.

Surgical endodontics/extraction and histopathological examination

When the prognosis of the teeth in question was poor, they were extracted under local anesthesia along with curettage of the sockets. When the prognosis was favorable, the patients were subjected to endodontic treatment, followed by periapical surgery under local anesthesia. The tissue thus obtained by curettage of the socket after extraction or by periapical surgery was subjected to histopathological examination. The lesions were then classified according to the following diagnostic criteria: [10]

Periapical granuloma

Specimen showing proliferating endothelial cells and capillaries, young fibroblasts, minimal amount of collagen, and chronic inflammatory cells (lymphocytes, plasma cells, macrophages) was diagnosed as periapical granuloma. Occasionally, nests of odontogenic epithelium, Russell bodies, foam cells, and cholesterol clefts may be present.

Periapical cyst

Specimen showing a layer of stratified squamous epithelium lining the cystic lumen with connective tissue wall composed of parallel bundles of collagen fibers and inflammatory cell infiltrates, predominantly lymphocytes and plasma cells was diagnosed as periapical cyst. Variable number of proliferating endothelial cells, capillaries, young fibroblasts, foam cells, Russell bodies, and cholesterol clefts may be present.

Periapical abscess

Specimen showing acute inflammation characterized by the presence of a distinct collection of polymorphonuclear leukocytes (PMN) within an already existing chronic granuloma was diagnosed as periapical abscess.

Statistical analysis

The data were tabulated and subjected for statistical analysis using Kappa statistic for inter-observer variability and Mann-Whitney U test. The diagnostic accuracy, sensitivity, and specificity of the various imaging modalities were calculated.


   Results Top


Periapical lesions were identified by the three diagnostic modalities in all the cases. The mean sizes of lesions differed slightly, with a decreasing trend observed from conventional radiography to ultrasonography (the measurements with ultrasonography were the lowest) as shown in [Table 1]. Statistical analysis of the lesions correctly identified by all the observers and ultrasound, when compared with histopathology are given in [Table 2]. There were 19 cases of periapical granuloma [Figure 1] and 11 cases of periapical cysts [Figure 2]. The maximum agreement of 72.7% was achieved for periapical cysts in the second observation, whereas the controversy for periapical granuloma was higher, with an agreement of 26.3% in the second observation.
Figure 1: (a) Conventional radiograph (CR) image showing well-circumscribed periapical radiolucency in relation to 11, measuring <1.5 cm, suggestive of periapical granuloma. (b) Digital radiograph (DR) image showing well-circumscribed periapical radiolucency in relation to 11, measuring <1.5 cm, suggestive of periapical granuloma. (c) US image reveals rich vascular supply on color Doppler examination suggestive of periapical granuloma. (d) Photomicrograph of periapical granuloma with inflammatory cells

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Figure 2: (a) Conventional radiograph (CR) image showing well-circumscribed periapical radiolucency with sclerotic border in relation to 11, 12, measuring >1.5 cm, suggestive of periapical cyst. (b) Digital radiograph (DR) image showing well-circumscribed periapical radiolucency with sclerotic border in relation to 11, 12, measuring >1.6 cm, suggestive of periapical cyst. (c) US images reveal a hypoechoic well-contoured cavity surrounded by reinforced bone walls. (d) Photomicrograph showing periapical cyst with epithelium (e), connective tissue (CT), and cystic lumen (CL)

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Table 1: Mean size of lesions as described by the three diagnostic modalities


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Table 2: Statistical analysis of lesions detected by all modalities as agreed upon by the three observers


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The observations made during the first and second time by the three observers with respect to the three lesions are summarized in [Table 3]. Observer B identified the periapical granuloma and cyst correctly for maximum lesions, both with conventional and digital radiographs. However, Observer A had the highest reliability or precision, with similar diagnosis in first and second observations. The intra-examiner agreement was the highest for conventional radiographs for Observer A and digital radiographs for Observer C, as shown in [Table 4]. Using Kappa test, the intra-examiner agreement for conventional radiographs between A1-A2, B1-B2, and C1-C2 was 93.33%, 76.67%, and 83.33%, respectively. The agreement for all observers was highly significant and did not happen due to chance (P < 0.0000). The agreement for digital radiograph between A1-A2, B1-B2, and C1-C2 was 86.67%, 80.00%, 89.66%, respectively, (P < 0.0000) similar to conventional radiographic observations.
Table 3: Correct/incorrect identification of lesions by the three observers in comparison with USG and histopathology


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Table 4: Intra-examiner agreement/calibration between first and second observations in different methods as determined by kappa statistic


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The inter-examiner agreement was comparable among the observers, as compiled in [Table 5]. Using Kappa procedure, the inter-examiner agreement for conventional radiographs with first and second observations between observers A-B, A-C, and B-C was 76.67%, 80.00%, and 76.67%, and 86.67%, 73.33%, and 80.00%, respectively, and was not due to chance (P < 0.0000). Similarly, for digital radiographs, the inter-examiner agreement during the first and second observations between observers was 70.00%, 70.00%, and 80.00%, and 83.33%, 86.67%, and 83.33%, respectively, and was not due to chance.
Table 5: Inter - examiner agreement/calibration between examiners A, B, and C in conventional radiograph method using both observations


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The diagnostic validity of all the modalities as per the observations made by different observers for periapical granuloma and cyst are tabulated in [Table 6]. The diagnostic accuracy of ultrasonography was higher than the observations made by conventional and digital radiographs by observers A and B. However, observer C had a better diagnostic accuracy with digital radiographs. When the diagnosis made by conventional radiograph, digital radiograph, and ultrasound were compared with histopathology for the first observation using Mann-Whitney U test, there was no significant difference in diagnosis (P = 0.2973, 0.4247, and 0.7007, respectively) [Table 7]. However, there was a slight significant difference in diagnosis for conventional radiograph (P = 0.0460) and no significant difference for digital radiograph and ultrasound when compared to histopathology (P < 0.4464 and 0.7007, respectively) in the second observation [Table 8].
Table 6: Diagnostic validity for different lesions by various observers


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Table 7: Comparison of four methods (conventional radiograph, digital radiograph, ultrasound and histopathology) for the first observation by Mann-Whitney U test


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Table 8: Comparison of four methods (conventional radiograph, digital radiograph, ultrasound, and histopathology) for the second observation by Mann-Whitney U test


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   Discussion Top


Radiographs are indispensable in oral diagnosis and endodontic practice. They are important for diagnosis, treatment planning, and for monitoring the outcome during follow-up. Certain radiographic features like size and shape of the lesion along with the presence of a sclerotic border are usually considered while rendering the diagnosis. Though the probability of occurrence of a cyst increases in larger lesions, Nair had reported that periapical lesions cannot be differentiated as cystic and non-cystic with radiographs alone. [11] Furthermore, it had been established that few granulomas larger than 2.5 cm in diameter probably represent a resolving chronic alveolar abscess. [12] Carrilo et al. reported that no relation existed between the presence of radiopaque border and the histopathologic diagnosis of the cysts. [13]

It is important to differentiate between periapical granuloma and periapical cyst as it helps not only in treatment planning and predicting the treatment outcome, but also in reducing the failure rates. The conventional root canal therapy is the main treatment modality for periapical granuloma, but does not hold good for periapical cysts, as true cysts require surgical intervention for successful management. On the other hand, appropriate diagnosis may also prevent overtreatment in cases that would have necessitated root canal therapy alone. To decipher this puzzle, sophisticated methods have been used for radiographic diagnosis, in order to provide better details of normal and pathologic structures with multiplanar imaging such as CT-scan, ultrasound real time imaging, etc. [14]

Ultrasound real-time imaging is more convenient than other imaging modalities because it is less expensive and generates lesser biologic adverse effects. Ultrasound with Color Power Doppler has the potential to supplement conventional or digital radiography in diagnosing periapical lesions in case of doubt by providing accurate diagnosis, thus helping in treatment planning and follow-up of periapical lesions. [7],[8] In the present study, the three modalities showed presence of periapical lesions in all the cases. The ultrasound measurements were almost always smaller than corresponding radiographic measurement with a mean of SI measurement of 8.7 mm and a mean of MD measurement of 9.2 mm, similar to the findings reported by Gundappa et al. [15] and Raghav et al. [9] However, some others did not measure the dimensions, but only considered diagnosis. [14],[16],[17] The variation of the size of the lesions on ultrasound could be due to the acoustic shadow cast by the edges of the bony cavity, depicting a smaller hypoechoic/anechoic lesion.

Statistical analysis using interclass correlation showed that the three observers were in moderate agreement with each other, which was closely coincident with a study done by Gundappa et al. [15] Out of the 30 cases in the present study, there was unanimous agreement among all modalities in 6 and 5 cases of periapical granuloma and 5 and 8 cases of periapical cysts in the first and second observations, respectively. However, in the rest of 19 and 17 cases in the first and second observations, there was disagreement between the observers. Ultrasonological diagnosis was only erroneous in five cases, two each of granuloma and cyst and one granuloma case labeled as abscess. It can thus be inferred that the echostructure of the lesions on ultrasound had a better correlation with histopathology than the radiological diagnosis.

In the present study, a substantial to almost perfect agreement was found in the first and second observations between the three observers A-B, A-C, and B-C using conventional and digital radiographs (ranged between 0.70 and 0.89), which was higher than that reported by Bohay [18] (0.54), who studied diagnosis of periapical lesions in posterior teeth using conventional radiography, and 0.08-0.25 reported by Paurazas. [19] However Gundappa et al. concluded that there was no significant difference between the three observers using conventional radiograph. [15] In the present study, the diagnostic accuracy of ultrasonography was higher than the observations made by conventional and digital radiographs by observers A and B. This was in accordance with previous ultrasonographical studies that reported accurate differentiation between periapical granuloma and cysts. [15],[16],[17] On the contrary, Observer C had a better diagnostic accuracy with digital radiographs. Observer A fared a better diagnosis using conventional radiographs. This was similar to the findings of Friedlander et al., [20] where the evaluators found all digital images inferior to conventional radiographs in visualizing bone lesions regardless of whether the lesion was large or small. The diagnostic accuracy of observers B and C was better with digital radiograph in comparison to conventional radiographs. The overall diagnostic accuracy of observers in decreasing order was B, A, followed by C. The sensitivity and specificity for periapical cysts by all modalities (with majority of observers) fared better than for periapical granuloma.

In the present study, the diagnosis carried out using ultrasound was compared with histopathology using Mann-Whitney U test, which showed no significant difference in diagnosis (P < 0.7007). Out of 30 cases, 25 cases diagnosed by ultrasound were confirmed with histopathology. The present study has confirmed that ultrasound imaging provides sufficient information with regard to the nature of the periapical lesions unlike conventional and digital radiography and is a reliable diagnostic technique for differentiating periapical lesions, i.e. periapical cysts and granulomas, based on the echotexture of their contents and the presence of vascularity using color Doppler.


   Conclusion Top


Our study revealed that ultrasound with color Doppler was an efficient tool for diagnosing periapical lesions as it had better diagnostic accuracy than conventional and digital radiography. The echostructure of the lesions and the presence of vascularity on ultrasound with color Doppler had a better correlation with histopathology than the radiological diagnosis. Hence, ultrasound imaging has a potential to be used as an adjunct to routine use of conventional and digital radiography in the diagnosis of periapical lesions, especially while formulating a working diagnosis. The limitations of ultrasonography, such as operator dependency and difficulty in identifying the lesions, can be overcome by establishing diagnostic criteria and rigorous training. Currently, using ultrasound is possible only in cases with windows in bone or with an alteration of bone architecture to permit the penetration of ultrasound waves. However, further refinement in the technique may overcome this obstacle and ultrasound imaging may find newer applications in endodontics.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

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    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]



 

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