Attempt at Roentgenographic Visualization of the Thoracic Duct and Cisterna Chyli

Abstract

No record of an attempt at roentgenographic visualization of the thoracic duct and cisterna chyli has been found in the literature. Yet demonstration of these structures on the x-ray film might prove of value in the diagnosis of mediastinal lesions, as well as yield information on the physiology and abnormalities of lymph flow. This study is presented to prevent needless duplication of effort by other workers who might attempt such demonstration. Theoretical Considerations A large portion of the fats absorbed from the intestine passes through the lacteals and the thoracic duct. It occurred to the author that following ingestion of iodized oil, sufficient concentration of iodine might be obtained in the thoracic duct and cisterna chyli to make possible roentgenographic visualization of these structures. Several problems were considered in order to determine the validity of this conception. Anatomy (5): The thoracic duct, which is the main trunk of the lymphatic system, receives all the lymphatics below the diaphragm. At its origin, which is usually opposite the twelfth thoracic vertebra, there is frequently a dilated portion known as the cisterna chyli (or receptaculum chyli). The duct is from 4 to 6 mm. in diameter. It passes through the aortic opening in the diaphragm, then inclines to the right and passes upward between the aorta and the azygos vein to about the fourth, fifth, or sixth thoracic vertebra, where it bends to the left and, continuing upward, passes over the apex of the left lung. It then curves downward to open into the left subclavian vein. By placing an opaque catheter in the thoracic duct of a cadaver, it was observed that the best view for demonstrating the lower portion of the duct was the anteroposterior left oblique with 30° rotation. The lateral view was also satisfactory. Digestion and Absorption of Iodized Oil: Iodized oils generally pass through the stomach unchanged (1). In the small intestine, according to Metzger (8) and Winternitz (13), iodine is not separated from the oil. Iodized oil is absorbed in the intestine (6, 7, 13), but there is no information as to whether it enters the lacteals or the blood vessels. One may only assume that it traverses the lacteals as do non-iodized oils. This assumption is supported by evidence (4) that fats absorbed in large particles or those having heavy molecular weights enter the thoracic duct. Iodized oils have a high molecular weight. As most authors agree that fine emulsification of fat increases its absorption, the iodized oil used in' this study was carefully emulsified. Since glycerophosphoric acid increases absorption of fats (12), elixir of glycerophosphates was given previous to administration of the iodized oil in some cases. Iodipin (iodized sesame oil) rather than any other halogenated, highly absorbable fat or related compound was selected for use because of its frequent mention in the literature and its relatively low toxicity.