|Year : 2015 | Volume
| Issue : 3 | Page : 359-365
Efficacy of scintigraphy as a diagnostic aid in oral and maxillofacial pathologies: A comparative radionuclide-radiographic study
Ankur Singh1, Nitin Agarwal2, Kamala Rawson1, Basavaraj N Kallalli1, Abhishek Sinha2, Yatriben Sandesara1
1 Department of Oral Medicine and Radiology, Narsinhbhai Patel Dental College and Hospital, Visnagar, Gujarat, India
2 Department of Oral Medicine and Radiology, Sardar Patel Post Graduate Institute of Dental and Medical Sciences, Lucknow, Uttar Pradesh, India
|Date of Submission||02-Dec-2014|
|Date of Acceptance||19-Nov-2015|
|Date of Web Publication||25-Nov-2015|
House No. 18, Sector 14, Indira Nagar, Lucknow - 226 016, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aims and Objectives: The aim of this study was to investigate various lesions involving the oral and maxillofacial region by using scintigraphy and to compare the findings with those of conventional radiograph. Materials and Methods: Nineteen subjects of all age groups and both sexes who reported to the outpatient department of Oral Medicine and Radiology and had been clinically diagnosed with diseases of oral and maxillofacial region were selected. Conventional radiography and scintigraphy were performed for all the subjects. Biopsy and histopathological investigations were preformed to confirm the diagnosis and on the basis of which sensitivity, specificity, positive predictive value, and efficiency of conventional radiography and scintigraphy were evaluated. Results: Conventional radiography was found to have 94.11% sensitivity, 50% specificity, 94.11% positive predictive value, and 89.47% efficiency. Scintigraphy was found to have 100% sensitivity, 14.28% specificity, 66.66% positive predictive value, and 68.42% efficiency. Conclusion: Scintigraphy is a very sensitive diagnostic aid, but lacks in specificity. Conventional radiography, on the other hand, has good sensitivity and relatively better specificity. For a proper diagnosis, scintigraphic findings must be correlated with clinical, radiological, and histopathological findings.
Keywords: Conventional radiography, radionuclide imaging, sensitivity and specificity, Tc-99m pertechnetate, technetium
|How to cite this article:|
Singh A, Agarwal N, Rawson K, Kallalli BN, Sinha A, Sandesara Y. Efficacy of scintigraphy as a diagnostic aid in oral and maxillofacial pathologies: A comparative radionuclide-radiographic study. J Indian Acad Oral Med Radiol 2015;27:359-65
|How to cite this URL:|
Singh A, Agarwal N, Rawson K, Kallalli BN, Sinha A, Sandesara Y. Efficacy of scintigraphy as a diagnostic aid in oral and maxillofacial pathologies: A comparative radionuclide-radiographic study. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2022 Jan 29];27:359-65. Available from: https://www.jiaomr.in/text.asp?2015/27/3/359/170449
| Introduction|| |
Two events of the past lead to the introduction of the field of nuclear medicine: First, when Sir Henri Becquerel discovered radioactivity in 1896  and second, when Madame Marie Sklodowska Curie coined the term "radioactivity."  Technetium-99 metastable ( 99m Tc) is the most commonly used radionuclide in scintigraphy (radionuclide imaging), which was discovered in 1937 by Carlo Perrier and Emilio Segrè.  In 1971, Subramanian and McAfee labeled technetium to methylene diphosphonate (MDP), which is at present the most common method for the imaging of bone in nuclear medicine. 
Bone scintigraphy has been found to be a very sensitive method for detection of osteoblastic activity in the skeleton; it consists of intravenous administration of 99m Tc-MDP. 99m Tc is most desirable as it has a short physical half-life of 6 h and 140 keV gamma energy. The distribution of radionuclide is imaged using a scintillation camera which records the gamma rays emitted by the 99m Tc from inside the patient.  Bone scintigraphy has several advantages over specialized imaging modalities, which has high sensitivity in detecting lesions, assessment of parenchymal function and excretion fraction of major salivary glands,  and detection of skeletal metastases.  Whereas plain radiographs, CT, and MRI are classified as structural imaging modalities, bone scintigraphy is a functional method. Still in many cases, radionuclide imaging techniques are the only means by which early physiologic changes that are a direct result of biochemical alteration may be assessed, before significant bone mineral changes can be detected by other means. 
| Materials and Methods|| |
This study was conducted after obtaining approval from the ethical committee of the institution. Nineteen subjects of all age groups and both sexes were recruited from the outpatient department of Sardar Patel Post Graduate Institute of Dental and Medical Sciences (SPPGIDMS). Patients who were excluded from the study were those found to have allergy to 99m Tc-MDP, those who had undergone traumatic injury, those with graft placed in oral and maxillofacial region, pregnant ladies, and those who were not mentally sound. All the subjects were informed of the study to be done, and an informed consent was obtained from all the patients. Subjects included were those pre-diagnosed clinically with developmental anomalies, inflammatory lesions, cysts, benign tumors, malignant neoplasms, fibro-osseous lesions of the oral and maxillofacial region, and salivary gland diseases. All the patients were evaluated by conventional radiography at SPPGIDMS and scintigraphy which was carried out in the Department of Nuclear Medicine at Sanjay Gandhi Post Graduate Institute of Medical Sciences (SGPGIMS), Lucknow.
Acquisition and analysis of radiographs
Conventional analogue radiography was done using standard intraoral radiographs. While for extraoral radiography, digital images were acquired using conventional panoramic radiographic machine (Planmeca Proline CE) and PSP cassettes (Fujifilm FCR Cassette type CC, 8″ × 10″). All the radiographs were analyzed by the experts of Oral Medicine and Radiology, as mentioned in the textbook of Oral Radiology: Principles and Interpretation.  A systematic approach was followed for detection of an abnormality in an image/radiograph either on intraoral or extraoral image for different types of radiographs. After the detection of the abnormality, the location (site, size, shape), periphery, internal structure, and the effect of the abnormality on adjacent structure were assessed.
Acquisition and analysis of scintigram
Scintigraphy was carried out for all the patients after complete radiographic evaluation. Bone scintigraphy and salivary gland scintigraphy were done in patients with diseases involving bone and salivary glands, respectively. Salivary gland scintigraphy was performed after injecting the patient intravenously with technetium-99m pertechnetate having 259 MBq activity in the median cubital vein, while the patient was lying supine over the patient bed of GE Infinia Hawkeye 4 with dual detector machine. Images were obtained continuously for 30 min. The entire time period was divided into flow phase (till 15-20 s after injection), concentration phase (from 1 min to 10 min after injection), and washout phase (after 10 min of injection). Before the washout phase, the patient was made to suck a lemon (sialogogue) to induce salivation after 10 min. Only front views were acquired, as in lateral views the salivary glands of both the sides get overlapped.
Bone scintigraphy was performed after injecting the patient intravenously with 99m Tc-MDP with 740 MBq activity in the median cubital vein, while the patient was lying supine over the patient bed of the GE Infinia Hawkeye 4 machine. Flow phase was acquired immediately following the injection and blood pool phase was acquired within 10 min of injection. After this, each patient was given a waiting period of 3 h in which the patient was asked to drink two or more glasses of water before delayed images were acquired. Each patient was asked to urinate frequently, especially before acquiring the delayed image after 3 h of waiting period. A delayed image was taken after 3 h of waiting period for 20 min. Front, right lateral, and left lateral views were acquired. A whole body planar view was also acquired for all the patients. The individual scintigrams were examined by the experts of Oral Medicine and Radiology and Nuclear Medicine for the ability of scintigrams to detect a disease as compared to the findings on radiographs.
Biopsy and histopathological investigations were performed where required for confirmation of clinical, radiographic, and scintigraphic findings.
Statistical analysis was done for both conventional radiography and scintigraphy. True positive was designated as any/both imaging modalities conforming to the histopathological diagnosis and also identifying the same disease process. False positive was designated as any/both imaging modalities not conforming to the histopathological diagnosis, and identifying a disease process which has not been identified histopathologically. True negative was designated as any/both imaging modalities conforming to the histopathological diagnosis and excluding the presence of the disease process. False positive was designated as any/both imaging modalities not conforming to a disease, while a disease is diagnosed histopathologically.
Sensitivity, specificity, positive predictive value, and efficiency were calculated. Sensitivity was calculated as (true positive/[true positive + false negative]) × 100, specificity was calculated as (true negative/[true negative + false positive]) × 100, positive predictive value was calculated as (true positive/[true positive + false positive]) × 100, and efficacy was calculated as ([true negative + true positive]/[true positive + false positive + true negative + false negative]) ×100.
| Results|| |
All the 19 subjects were subgrouped under the following categories on the basis of clinical diagnosis:
On scintigraphy, lesions appeared as either white (cold spots) or black (hot spots) denoting less or no uptake and an increased uptake of the radionuclide, respectively. Slight hot spots were present throughout the skeleton, and area with a lesion showed a change in appearance. The statistical analysis for calculation of sensitivity, specificity, positive predictive value, and efficiency of conventional radiography and scintigraphy was based on the results of histopathological investigations [Table 1].
- Developmental anomalies of the jaw [n = 1 (5.26%)].
- Inflammatory lesions of the jaw [n = 3 (15.78%)].
- Cysts of the jaw [n = 5 (26.31%)].
- Benign tumors of the jaw [n = 3 (15.78%)].
- Malignant neoplasms of the jaw [n = 4 (21.05%)].
- Fibro-osseous lesions of the jaw [n = 1 (5.26%)].
- Salivary gland diseases [n = 2 (10.52%)].
|Table 1: Comparison of fi ndings of clinical, radiographic, scintigraphic, and histopathological examinations|
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Results of conventional radiographic analysis
Out of 19 subjects examined by conventional radiography, there were 16 subjects found to be true positive showing characteristic features of the respective diseases, 1 false-positive case of squamous odontogenic tumor not diagnosed by radiography but was diagnosed only by histopathology, 1 true-negative case, and 1 false-positive case [Table 2].
|Table 2: Comparison of radiographic fi ndings with histopathological diagnosis|
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Results of scintigraphic analysis
Out of 19 subjects examined by scintigraphy, 12 were true positive, 6 were false positive, and 1 was true negative [Table 3].
|Table 3: Comparison of scintigraphic fi ndings with histopathological diagnosis|
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Results of statistical analysis
On statistical analysis, conventional radiography was found to have 94.11% sensitivity, 50% specificity, 94.11% positive predictive value, and 89.47% efficiency. Scintigraphy was found to have 100% sensitivity, 14.28% specificity, 66.66% positive predictive value, and 68.42% efficiency.
| Discussion|| |
Scintigraphy takes the advantage of constant turnover of bone in response to metabolic or mechanical demands. Most diseases involving bone result in increased turnover or new formation of bone. On scintigraphy, these areas appear as areas of increased radionuclide uptake, called "hot spots." Decreased uptake is associated with metabolically inactive bone, lack of osteogenesis, or an absent vascular supply. It also indicates lack of reparative response and suggests the presence of an aggressive lesion. Photon-deficient region or photopenic abnormalities are those areas where there is diminished or absent uptake and are called "cold spots." 
In the condylar hyperplasia of the right side, bone scintigraphy revealed hot spots in the region of right condyle, suggesting current growth. Radiography could only detect the elongated condylar neck without any detection of current growth. Similar findings were reported by studies conducted by Pripatnanont et al.,  Dalili et al.,  and Mehrotra et al. 
In chronic osteomyelitis, radiography revealed a lesion of the jaw with moth-eaten appearance and multiple sequestrum, while scintigraphy showed more extension than radiography, localized the lesion only to a region of jaw, and showed extensive hot spot suggestive of increased bone metabolism [Figure 1]. Similar findings were obtained by Bergstedt and Lind  and Hofer et al.,  who reported that in osteomyelitis, extensive hot spot appears over the region of jaw with extension more than that on radiographs. Few inflammatory cells were found in our cases on incisional biopsy.
|Figure 1: A planar scintigram of skull showing the right lateral view with an extensive area of hot spot over the body, ramus, and condyle|
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Other periapical, periodontal, and pericoronal inflammatory lesions were also seen in patients with carcinomas and other pathologies. Scintigraphy produced a diffuse hot spot in the region of the alveolar process, but the nature of the lesion could not be identified. A similar finding was reported by studies conducted by Garcia et al.,  Alexander et al.,  and El-Zahry and Sinzinger.  Common inflammatory dental diseases appear as areas of hot spot and are difficult to differentiate.
In case of radicular cysts, radiographs were very diagnostic as they clearly revealed an oval (most commonly found shape in this study) radiolucency with corticated/sclerotic margin, while the appearance on scintigram was similar to that observed by Hofer et al.  who described oval or round appearance of most of cysts of the jaw on scintigram which helped in their detection. On incisional biopsy, the radicular cysts were found to be lined by nonkeratinized stratified squamous epithelium along with a number of lymphocytes and Russell bodies, which helped to confirm the diagnosis.
In case of ameloblastomas, radiography revealed a multilocular radiolucency involving the body and ramus, while scintigraphy showed only intense hot spot, localized to the jaw and appearing like a "doughnut," although it showed more extension than was found in radiographs [Figure 2]. Similar findings were obtained by Shibuya et al.  and Hofer et al.,  who reported a geographic pattern of bone destruction with well-delineated margins on radiographs in cases of benign tumors and presented increased hot spot at the periphery. Nonkeratinized epithelium, basal palisading, epithelial invaginations, and subepithelial hyalinization were found on histopathological examination of ameloblastomas.
|Figure 2: A scintigram of skull showing a region of hot spot over the left body and ramus of the mandible, which also surrounds an area of cold spot over the ramus|
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In case of malignancies involving the jaws, radiography revealed a moth-eaten lytic lesion with destruction of cortex. Scintigraphy showed better extension and better margins than radiography. The increased bone metabolism surrounding a malignant process, where the bone formation was increased, showed increased radionuclide uptake and appeared as an intense hot spot. Similar findings were observed by Hofer et al.  and Fischer-Brandies and Seifert,  who reported similar findings and also a number of false-positive results when compared with histologic examination of osseous infiltration, due to periradicular, tumor-independent processes as well as concomitant inflammation presenting in a similar manner, which can also result in a change of osseous metabolism with an accumulation of the radionuclide. Multiple tumor islands invading the bony tissue, pleomorphic squamous cells with atypical nuclei, and hyperchromatism were seen in the tumor islands on histopathological examination.
In case of cementoblastoma, radiography revealed a mixed radio-opaque and radiolucent lesion, which was predominantly radio-opaque, having well-defined margins and surrounded by a radiolucent band, giving an amorphous appearance. Scintigraphy, on the other hand, showed an intense round hot spot localized to the jaw [Figure 3]. Both the imaging modalities showed fine margins, with radiography findings being better than scintigraphy. A similar finding was observed in a study by Harada et al.  On histopathological examination, dense mass of mineralized cementum-like material with intervening well-vascularized soft tissue containing cementoblasts was found.
|Figure 3: A scintigram of skull showing the front view with an area of intense hot spot over the left body of the mandible|
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In case of xerostomia, scintigraphy showed diffuse, bilaterally symmetrical hot spots in the region of the major salivary glands, suggesting normal functioning of the salivary glands and no sign of any salivary gland disease. This was not in accordance with the appearance of salivary gland in patients with Sjögren's syndrome, in which the radionuclide uptake and velocity of saliva with radionuclide reduces and it has been found to correlate with the histopathological findings of the labial biopsy.  The pattern of radionuclide uptake by salivary glands in our case was similar to those reported by van den Akker and Sokole,  who studied scintigraphy in normal subjects, and Anjos et al.,  who reported similar appearance of radionuclide uptake by major salivary glands.
In case of sialolithiasis, a retained hot spot was found in the right submandibular salivary gland region in the washout phase of salivary gland scintigraphy, which was suggestive of an obstruction to the salivary flow, although the type of obstruction could not be identified. Similar findings were observed by van den Akker and Busemann-Sokole,  who found that absolute indication for scintigraphy exists when the ductal orifice of one or several major salivary glands cannot be found or cannulated due to developmental anomalies, obstructive disorders, traumatic lesions, and fistulae, and there is need of postsurgical information after glandular excision or after ligation or repositioning of a major excretory duct.
Statistical analysis was done to assess the accuracy of scintigraphy and conventional radiography. Hence, we calculated sensitivity, specificity, positive predictive value, and efficiency for radiography and scintigraphy based on the biopsy and histopathological findings. Scintigraphy had 100% sensitivity, while radiography had better specificity, positive predictive value, and efficiency than scintigraphy. Zupi et al.  reported the sensitivity, specificity, positive predictive value, and efficiency of radiography and bone scintigraphy, where radiography was 69.6% sensitive, 66.7% specific, with 64% positive predictive value, and 68% efficient, while bone scintigraphy was 100% sensitive, 66.7% specific, with 71.9% positive predictive value, and 82% efficient. Müller and Slootweg,  on the other hand, reported higher sensitivity of X-rays (97%) in detecting jaw bone involvement by oral squamous cell carcinoma. This was somewhat similar to the sensitivity we have obtained from radiography in our study. In our study, the sensitivity was found to be similar, while other values were significantly low for bone scintigraphy and the values were significantly higher for conventional radiography. The difference between the results of our study and the results obtained in previous studies could be due to the difference in the type and size of sample selected; previous studies were mostly done on oral cancer, while we chose to study several types of oral and maxillofacial diseases. Their results were mostly applicable for the study of oral cancer, while our study included different types of oral and maxillofacial diseases.
In the present study, scintigraphy images were found to be quite nonspecific for any disease and could only determine the presence and absence of active metabolism at a site of the jaw. The nature of the lesion could not be assessed. These findings were similar to the findings of Jamdade and John,  who reported that the hot and cold areas or spots in the scintigraphy image are just the result of altered metabolism at the region, and based on which a definitive diagnosis cannot be made.
| Conclusion|| |
To conclude, scintigraphy is a diagnostic modality with high sensitivity, but lacking in specificity, positive predictive value, and efficiency. Radiography, on the other hand, has good sensitivity and relatively better specificity, positive predictive value, and efficiency. For a proper diagnosis, scintigraphic findings must be correlated with clinical, radiological, and histopathological findings.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]