Die Cisterna chyli: Evaluation von Prävalenz, Charakteristika und prädisponierenden Faktoren anhand von Computertomographien

Abstract

In this retrospective study computer tomographies (CT) of 3000 patients were evaluated to determine the prevalence, morphological characteristics and potential predisposing factors, which can contribute to the development of a cisterna chyli (CC). The evaluation of all 3000 CTs occurred consecutively, in which exclusively contrast enhanced CT examinations of the chest and/or abdomen were included. The verification of a CC, the size, the volume, the attenuation as well as the localization were correlated with the anamnestic and clinical data of all patients. Among all 3000 patients 484 CC (16,1 %) were definitely existent by a small male predominance. The mean distention of a CC was sagittal 5,9 mm, transversal 6,4 mm and craniocaudal 13,1 mm, corresponding a mean volume of 302 µl. The mean attenuation of all CC was 4,8 Hounsfield units (HU). More than every 4th CC (28,3 %) showed CT densities above 10 HU. To use the CT attenuation similar to water as an exclusive distinctive feature between a CC and an augmented retrocrural lymph node can lead easily to misinterpretation. A much safer method to distinguish the CC from a retrocrural lymph node independently of the CT attenuation is to detect the continuity of the CC into the thoracic duct. Among the senior age patients there was significant more often a CC detectable than in younger age groups. Patients with malignancies showed a significantly higher prevalence (p < 0,001) for a CC (341/1757; 19,4 %) than patients with benign conditions (143/1243; 11,5 %). The likelihood of suffering from a malignant disease was in the cohort with a CC 70,5 % compared to the baseline percentage of malignancy of 58,6 % in all 3000 patients. With a CC - volume of 800 µl the likelihood of malignancy goes up from 70,5 % to 94,1 % starting at a volume of 1000 µl. The calculation of the relative risk showed that the finding of a CC larger than 1000 µl increases the risk for malignancy by a factor of 1,7 (p = 0,0017).