Abstract
Background and Objectives:
To assess the diagnostic capability of real-time ultrasound imaging, together with the application of color power Doppler in the identification and differential diagnosis of the periapical lesions.
Materials and Methods:
Fifteen patients with periapical lesions of pulpal origin, diagnosed with clinical and conventional radiographic examination, were examined further using ultrasonography. The results from the biopsies of the lesions were compared and statistically analyzed.
Results:
The differential diagnosis between periapical granulomas and cystic lesions, which were based on the ultrasonographic findings, were confirmed by the results of the histopathologic examination in 13 (86.7%) of 15 cases, one being granuloma and 14 being cystic lesion.
Interpretation and Conclusion:
Ultrasound real-time imaging is a technique that may help make a differential diagnosis between cysts and granulomas by revealing the nature of the content of a bony lesion. This technique may have further applications in the study of other lesions of the jaws.
KEY WORDS: Color power doppler, diagnosis, echography, periapical lesions
Diagnostic ultrasonography, a safe, rapid, accurate, noninvasive, and easily reproducible dynamic modality providing “live” images, could be used to differentiate among solid, cystic, mixed, and dense cystic lesions.[1,2] Real-time imaging is used to study the moving parts of the body and to obtain a three-dimensional information by rapidly changing the sections of anatomy.[2,3] Using color power Doppler ultrasound, it is possible to evaluate and determine the presence and direction of blood flow within the ultrasonographic image of the tissue, together with information concerning flow, velocity, and perfusion of the area.[1]
The versatility of this method has proved its marked efficiency in the field of medicine, whereas it posses less exploration with little work in the field of dentistry. Ultrasonography, with its resourcefulness can fetch the differentiation among periapical lesions.
Materials and Methods
The study group comprised 15 patients of both sexes, with age ranging from 13 to 65 years, attending the outpatient department. Only those periapical lesions which appeared as radiolucent on the radiographs were included in the study group. Those periapical lesions which appeared as radiopaque on the radiographs were eliminated from the study group.
Ultrasonographic examination
All the subjects underwent ultrasonographic examination using GE Logic 400 MR3 color Doppler machine having multifrequency linear transducer using 7–11 MHz frequency at Sheethal Diagnostics, Davangere, India.
The patients were examined with multifrequency linear transducer. All the examinations including real-time and Color Doppler imaging were performed in the periapical area extraorally. The ultrasonographic images were analyzed based on the following principles:
Cystic lesion: A hypoechoic well-contoured cavity surrounded by reinforced bone walls, filled with fluid, and with no evidence of internal vascularization on color Doppler examination.
Granuloma: A poorly defined hypoechoic area, showing rich vascular supply on color Doppler examination.
Mixed lesion: Predominantly hypoechoic area with focal anechoic area, showing vascularity in some areas on color Doppler examination.
The results of ultrasound were correlated with radiographic and histological findings and were statistically analyzed.
Results
Correlation of histologic features with ultrasonographic findings
Out of the 15 subjects, 12 (80%) were diagnosed as periapical cyst ultrasonographically, whereas 14 (93.3%) were diagnosed as periapical cyst histopathologically and the correlation between ultrasonographic and histopathologic diagnoses was found to be in 12 (85.7%) subjects [Table 1 and Graph 1].
Table 1.
Correlation of histologic features with ultrasonographic findings
Graph 1.
Correlation of histologic features with ultrasonographic findings
Out of the 15 subjects, 2 (13.3%) were diagnosed as periapical granuloma ultrasonographically, whereas 1 (6.7%) was diagnosed as periapical granuloma histopathologically and the correlation between ultrasonographic and histopathologic diagnoses was found to be in 1 (50%) subject.
Out of the 15 subjects, 1 (6.7%) was diagnosed as periapical abscess ultrasonographically, whereas no subjects were diagnosed as periapical abscess histopathologically and there was no correlation between ultrasonographic and histopathologic diagnoses in this subject.
The correlation between histopathologic and ultrasonographic diagnoses was found to be in 13 (86.7%) subjects.
Diagnostic validity of ultrasonography
Comparing the results of ultrasonography with the histopathologic features, the sensitivity, specificity, positive predictive value, and negative predictive value of ultrasonography to diagnose periapical lesions were calculated. In our study, tp denotes true positive = 12 subjects, tn denotes true negative = 1 subject, fp refers to false positive = 2 subjects, fn is false negative = 0 subjects, and N is total number of patients = 15 subjects [Table 2 and Graph 2].
Table 2.
Diagnostic validity of ultrasonography
Graph 2.
Diagnostic validity of ultrasonography
Discussion
Correlation of histologic features with ultrasonographic findings
Out of the 15 subjects in the present study, ultrasonographic examination showed 12 (80%) periapical cysts whereas histopathologic diagnosis revealed 14 (93.3%) periapical cysts. One of the periapical cysts (2nd subject) was misdiagnosed ultrasonographically as periapical granuloma. This misinterpretation was because of the content of the lesion which showed high density equivalent to a solid lesion, even though with lack of vascular supply on color Doppler examination. Hence, it was diagnosed as periapical granuloma.
One of the periapical cysts (11th subject) was misdiagnosed ultrasonographically as periapical abscess [Figure 1]. This lesion showed both hypoechoic and anechoic regions, i.e., mixed echogenic patterns with numerous scattered internal echoes and varying density values within the lesion suggestive of periapical abscess. Similar to our observations, Dib et al.[4] in their study of 72 intraosseous lesions of the jaw could identify accurately only in 17 (73.9%) out of 23 cystic lesions. The reason for this could be due to the presence of thick cortical bone covering the lesion, the occurrence of infected cysts and solid areas within the cystic lesion. The cystic lesions on the ultrasound imaging appeared as anechoic lesion in six cases, turbid fluid in one case, scattered internal echoes in one case, and posterior enhancement in three cases [Figures 2 and 3].
Figure 1.
Ultrasonograph showing well-defined hypoechoic lesion with vascularity
Figure 2.
Ultrasonograph showing well-defined anechoic lesion
Figure 3.
Ultrasonograph showing well-defined anechoic lesion
The internal echoes present in infected cysts and odontogenic keratocyst could be due to dense particles (cholesterol clefts in the infected cysts) in the cystic fluid and keratin in odontogenic keratocyst. The density values varied within the lesion in case of infected cysts and odontogenic keratocyst, indicative of difference in the contents within the lesion, which reflects the disease process.
Out of the 15 subjects in the present study, ultrasonographic examination showed 2 (13.3%) periapical granuloma among which 1 (50%) was diagnosed histopathologically as periapical granuloma and the other as periapical cyst. This observation is similar to the observations made by Cotti et al.[5,6] and Gundappa et al,[3] where they had accurately diagnosed all the periapical granulomas (100%) ultrasonographically.
Thus, the observations from the present study infer that the diagnostic validity of ultrasonography is similar to that made by Dib et al,[4] where they have reported 92.8% accuracy and less compared to that made by Cotti et al,[5,6] and Gundappa et al.[3] where they have reported 100% accuracy.
Comparison of ultrasonography with conventional radiography
In all the subjects, conventional radiography provided the preliminary information about the lesion [Figure 4]. It pictorially represents the anatomic location of the periapical lesion in relation to the particular involved tooth and it provides size of the lesion [Figures 5 and 6], whereas ultrasound was able to accurately identify the underlying disease process reasonably accurately and the size measurements in three dimensions using the ultrasound software.
Figure 4.
Panoramic radiograph showing unilocular radiolucent lesion
Figure 5.
Occlusal radiograph showing unilocular radiolucent lesion
Figure 6.
Intraoral periapical radiograph showing radiolucent lesion
A major concern over the performance of ultrasonography was the difficulty in attributing the lesions to a specific area of the maxillary bone because the dental landmarks (i.e. roots) were not specifically visualized. This made it difficult to orient the lesion in the different regions of the mouth without using a reference radiograph.
Conclusion
With its potential usefulness to differentiate the periapical lesions, ultrasonography can be considered as a better imaging modality with improved efficacy when compared to conventional radiography. In comparision to histopathologic diagnosis, ultrasonography showed less accuracy and thus can be considered to be a supplementary tool in the differential diagnosis of periapical lesions. Further research can be directed in larger samples and in different types of periapical lesions to assess the diagnostic validity of ultrasonography.
Footnotes
Source of Support: Nil
Conflict of Interest: None declared.
References
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