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 . all the subjects underwent ultrasonographic examination using ge logic 400 mr3 color doppler machine having multifrequency linear transducer using 711 mhz frequency at sheethal diagnostics , davangere , india . 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 . 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 . all the subjects underwent ultrasonographic examination using ge logic 400 mr3 color doppler machine having multifrequency linear transducer using 711 mhz frequency at sheethal diagnostics , davangere , india . 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 . 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 . 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 ] . correlation of histologic features with ultrasonographic findings 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 . 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 ] . 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 ] . correlation of histologic features with ultrasonographic findings 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 . 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 ] . diagnostic validity of ultrasonography diagnostic validity of ultrasonography 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 ( 2 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 . one of the periapical cysts ( 11 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 . in their study of 72 intraosseous lesions of the jaw 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 ] . ultrasonograph showing well - defined hypoechoic lesion with vascularity ultrasonograph showing well - defined anechoic lesion 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 . and gundappa et al , 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 , where they have reported 92.8% accuracy and less compared to that made by cotti et al , and gundappa et al . where they have reported 100% accuracy . in all the subjects , 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 . panoramic radiograph showing unilocular radiolucent lesion occlusal radiograph showing unilocular radiolucent lesion 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 . 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 ( 2 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 . one of the periapical cysts ( 11 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 . in their study of 72 intraosseous lesions of the jaw 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 ] . ultrasonograph showing well - defined hypoechoic lesion with vascularity ultrasonograph showing well - defined anechoic lesion 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 . and gundappa et al , 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 , where they have reported 92.8% accuracy and less compared to that made by cotti et al , and gundappa et al . where they have reported 100% accuracy . 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 . panoramic radiograph showing unilocular radiolucent lesion occlusal radiograph showing unilocular radiolucent lesion 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 . 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 .
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 .