Thoracic duct scintigraphy by orally administered I-123 BMIPP: normal findings and a case report

To investigate the use of orally administered iodine-123-labeled 15-(4-iodophenyl)-3(R,S)-methyl-pentadecanoic acid (I-123 BMIPP) for thoracic duct imaging in normal and pathologic states and to study the tracer distribution and dynamics in healthy participants.

The radiotracer was administered with solid (in three healthy persons and one patient) or liquid meals (in three other healthy persons). Solid meals contained relatively more fat content than did the liquid meal. Images were acquired to trace the passage of radiotracer from the intestine to the systemic venous circulation via the lymphatic route. Multiple static planar images were acquired in the anterior and posterior views. Blood samples were analyzed for radioactivity and serum triglyceride levels.

In the healthy participants, I-123 BMIPP was absorbed from the intestine and reached the venous circulation through the thoracic duct. The thoracic part of the duct was visualized successfully in all healthy persons within 80 minutes. The radiotracer dynamics varied according to the type of meal administered. The patient had chylomediastinum and right chylothorax and underwent thoracic duct ligation. In the patient, marked stasis in the collateral lymphatic channels was seen, as was chylous leakage into the mediastinal space and right pleural cavity. Passage of tracer to the general venous circulation was delayed. A normal thoracic duct was not seen in this patient.

Scintigraphy by orally administered I-123 BMIPP is a simple method to image the thoracic duct and to monitor its lesions. Meals with a higher fat content result in better BMIPP absorption and may be used as a standard method.