Communication between peritoneal cavity and mediastinal lymph nodes demonstrated by Tc-99m albumin nanocolloid intraperitoneal injection.

Lymphatic drainage from the peritoneal cavity to mediastinal lymph nodes has been reported, indicating that abdominal fluid is not immobile. We studied this movement in rats receiving Tc-99m albumin nanocolloid which has smaller particle sizes than does Tc-99m microaggregated albumin colloid used for liver/spleen imaging. The Tc-99m albumin nanocolloid had a radiochemical purity of 99.33%-99.77% with free pertechnetate of 0.23%-0.67%. During pentobarbital anesthesia, thoracoabdominal images were obtained 4-6 hr after intraperitoneal injection of 350 mCi Tc-99m albumin nanocolloid with 5 ml of normal saline. The images showed symmetrical radiotracer localization in the mediastinal lymph nodes. Scintigraphic demonstration of drainage to the mediastinal region from the peritoneal cavity may be explained by flow directly into mediastinum through the lymphatic system, indicating lymphatic patency between the peritoneal cavity and mediastinum. Absence of visualization may indicate lymphatic block. This type of information concerning lymphatic drainage may have clinical impact for a patient with malignant or intractable ascites. The radionuclide technique is easily performed for this assessment.