Bilateral adrenal enhancement revised-adrenal-to-spleen ratio as an appropriate mortality predictor

Abstract

Purpose: To investigate whether adrenal gland radiodensities alone or set in relation to either the inferior vena cava (IVC) or the spleen can predict hospital mortality in intensive care unit patients.

Methods: One hundred thirty-three intensive care patients (90 males, age: 66.3 ± 14.5 years) with an acute clinical deterioration were included in this retrospective analysis. CT attenuation (Hounsfield units) of adrenal glands, IVC, and spleen was evaluated by 2 radiologists separately. Adrenal-to-IVC and adrenal-to-spleen ratios were calculated. Receiver operating characteristic (ROC) analysis, combined with the Matthews correlation coefficient (MCC) as a classifier, was used to assess which parameter is the most suitable for short-term, intermediate-term, and overall mortality prediction. Interrater agreement was assessed using intraclass correlation coefficient (ICC).

Results: The highest discriminative power to distinguish between deceased and survivors was found for the adrenal gland-to-spleen ratio for the 72-h mortality. A threshold of > 1.4 predicted 72-h mortality with a sensitivity of 79.31% and a specificity of 98.08% (area und the curve (AUC) = 0.94; p < 0.0001; MCCs = 0.81). The positive likelihood ratio was 41; the positive predictive value was 92.20%. Adrenal gland-to-spleen ratio was also best suited to predict the 24-h and overall mortality. ICCs of HU measurements in adrenal gland, IVC, and spleen indicated a high interrater agreement (ICC 0.95-0.99).

Conclusions: To conclude, the adrenal-to-spleen ratio in CT in portal venous phase may serve as an imaged-based predictor for short, intermediate, and overall mortality and as reproducible prognostic marker for patient outcome.

Keywords: Adrenal enhancement; Hospital mortality; Intensive care unit; Mortality prediction; Prognosis.

Fig. 1

Study flow chart with numbers/reasons of included/excluded patients

Fig. 2

a Abdominal CT scan of an 83-year-old woman with aortic dissection of the ascending aorta. White-colored arrow point to the left hyperdense adrenal gland (average HU adrenal gland: 75); white-colored circle within the spleen (averaged HU spleen: 95; adrenal gland-to-spleen ratio  ≈ 0.79). The patient survived. b Abdominal CT scan of a 78-year-old male patient with septic shock. White-colored arrow point to the left hyperdense adrenal gland (average HU adrenal gland: 160); white-colored circle within the spleen (averaged HU spleen: 93; adrenal gland-to-spleen ratio: ≈ 1.72). The patient died within 24 h after the imaging

Fig. 3

ROC curves comparison of best performing predictors for 72-h mortality. Highest area under the curve (= AUC) was found for adrenal-to-spleen ratio in portal venous phase (AUC = 0.94)