FULL PAPER Role of Tc-99m Ethambutol Scintigraphy in Diagnosing Tuberculosis in children with Scoring Systems as Diagnostic Approach

Background. Tuberculosis (TB) is world’s endemic infection, especially in developing countries. In children, tuberculosis infection can be seen as the great masquerade because have non-specific symptoms. Diagnosis of tuberculosis infection is more difficult in children because of chest x-ray are less specific; standard sputum samples are often difficult to collect; lower bacterial loads made microscopic and culture more difficult. Bacteriological examination as a gold standard is limited used in children. Several diagnostic approaches are developed to overcome diagnosis problem of TB in children. Various scoring systems and diagnostic classifications have been developed as screening test that may help clinical judgment in diagnosing tuberculosis in children. Among different scoring systems, the Keith-Edwards scale (WHO TB scores) is the most widely used in clinical setting. Kenneth-Jones' criteria (KJS) has been used in several centers as diagnostic approach in diagnosing TB. 99m Tc-Ethambutol SPECT/CT can be used to detect and to localize tuberculosis infection. The aim of this study is to describe the role of 99m TcEthambutol Scintigraphy in diagnosing tuberculosis in children based on KJS and WHO TB score as diagnostic approaches. Material and methods. Our study population comprised of 84patients (42 boys and 42 girls with age range 3–168 months). SPECT/CT was done 1 and 3 hours after injection of 7-444 MBq 99m Tc-Ethambutol. Sedation was given before acquisition for uncooperative patients to avoid movement. KJS and WHO TB score were used as diagnostic approach in diagnosing TB. KJS consists of variables such as: AFB smear, chest X-ray, BCG vaccination, granulomatous lesions in histophatological result, physical findings, tuberculin test, history of contact with TB patient or sputum smear positive, age below 2 years, history of anti tuberculosis drugs, and degree of malnutrition. According to KJS scoring system, score ≥ 7 indicates unquestionable TB. The variables in WHO TB score includes : duration of illness, nutritional state, history TB in family, tuberculin test, malnutrition, symtomp of fever and night sweats, local clinical findings of tuberculosis lesions. WHO TB scores ≥ 7 indicates a high likelihood of TB. Result. From total 84 patients, positive 99m Tc-Ethambutol scintigraphy were found in 52 of 58 patients with KJS ≥ 7 (89.66%) and 53 of 58 patient with WHO TB score ≥ 7(93.10%). Negative 99m Tc-Ethambutol scintigraphy was found in 32 subjects with KJS criteria < 7 (38.1%), and 30 subjects with WHO TB score < 7 (35.7%). Discordance of these results: 7 subjects (positive scintigraphy while negative KJS criteria), 6 subjects (positive scintigraphy while negative WHO TB score), and 1 subject (negative scintigraphy while positive KJS criteria or WHO TB score). Agreement result between 99m Tc-Ethambutol and KJS criteria; kappa index 0.843 (p < 0.001). Agreement result between 99m Tc-Ethambutol with WHO TB score; kappa index 0.815 (p < 0.001). There was no adverse effect observed from all subjects. 99m Tc-Ethambutol is safe, effective, and non-invasive diagnostic modality that can be used in children. Conclusion. 99m Tc-Ethambutol can be used as one of diagnostic modality to diagnose TB in children.