Tc-Ethambutol Scintigraphy with Single-Photon Emission Computed Tomography/Computed Tomography in Lymph Node Tuberculosis: An Initial Experience.

Purpose Of The Study: The purpose of the study is to evaluate Tc-labeled ethambutol (Tc-EMB) as a potential diagnostic agent in lymph node tuberculosis (LNTB).

Materials And Methods: A prospective pilot study was done at All India Institute of Medical Sciences, New Delhi. We included adult consenting patients who were diagnosed with LNTB and were either treatment naïve or had just started treatment. Patients were injected with 10-15 mCi of Tc-EMB. Whole-body anteroposterior planar imaging was done from 15 min after injection at serial intervals till 4-6 h along with one single-photon emission computed tomography-computed tomography (SPECT-CT) imaging with the help of a dual-head SPECT-CT gamma camera. The uptake of Tc-EMB was analyzed and corroborated with clinicoradiological findings.

Results: Between January 2019 and November 2020, we recruited 23 patients who underwent Tc-EMB, and 19 scans were interpretable and considered for analysis. Cervical lymphadenopathy was the most common presentation (13, 68.42%), followed by mediastinal (9, 47.36%) and abdominal (4, 21.05%) nodes. Other involvement included pulmonary (8, 42.1%), gastrointestinal (3, 15.78%), and chest wall abscess and bone marrow deposits in 1 patient each. A positive scan was noted in 7 (53.84%) patients with cervical lymphadenopathy, whereas uptake in abdominal and mediastinal lymph nodes was seen in 1 (25%) and 2 (22.22%) cases, respectively. Uptake in pulmonary lesions was noted in 3 (37.5%), but uptake in hepatic and splenic lesions was not seen.

Conclusion: Tc-EMB scan can demonstrate drug penetrance in some patients with LNTB and should be explored further with a larger sample size.