The Portal-Venous Enhancement Ratio of the Adrenal Glands and Spleen as a Short-Term Predictor of Mortality in Intensive Care Patients

Abstract

Background In critically ill ICU patients, initial results showed that opposite enhancement of the adrenal glands (↑) and spleen (↓) on portal venous CT scans was associated with increased mortality over the next days to a month, with short-term mortality being best predicted. The study aimed to validate the adrenal-to-spleen ratio determined in a pilot study concerning mortality prediction. Method 371 portal venous CT scans of 203 ICU patients (127 men, age: 68.1 ± 14.4 years) were included in the retrospective analysis. Region-of-interest (ROI)-based Hounsfield units of the adrenal glands and the spleen and their density ratio were evaluated. The Matthews correlation coefficient (MCC) and ROC analysis were used to establish a threshold for the adrenal-to-spleen ratio regarding mortality within 72 hours of imaging. The quality of the classification of survivors and deceased patients in the current collective based on the threshold determined in a pilot study and on the current threshold was determined. The precision-recall curve (PRC) was used to test the influence of the addition of patients with low vital risk on the ROC. Results The current threshold of 1.37 for the adrenal-to-spleen ratio provides good discriminatory power between those who died and those who survived (MCC: 0.87; sensitivity: 83.7 %; specificity: 99.1 %; PPV: 93.2 %; NPV: 97.6 %) and differs only slightly from the threshold of 1.41 determined in the pilot study, which consequently has comparable discriminatory power. Conclusion As a reproducible image-based prognostic marker, the portal venous adrenal-to-spleen ratio has a high predictive power for short-term death in ICU patients. It is, therefore, suitable as an indicator of high risk of death within 72 hours after imaging. Key Points:  Citation Format