Value of the CT “capsular sign” as a potential indicator of acute adrenal ischemia

Abstract

Acute adrenal ischemia represents a rare cause of adrenal insufficiency which should be promptly diagnosed in order to preserve adrenal vitality and function. Our study aims to retrospectively evaluate the diagnostic accuracy of the CT capsular sign as an indicator of adrenal ischemia and its association with vascular involvement. Between January 2013 and January 2014, 69 consecutive patients (47 men, 22 women; mean age 46; range 22-67) with suspected adrenal insufficiency based on clinical and biochemical data underwent 320-row CT examination in our Emergency Department. Written informed consent was obtained for the CT examinations, and the institutional review board approval was obtained for our retrospective study. CT multi-planar images were retrospectively and independently analyzed by two radiologists searching for the patency of adrenal vessels, enlarged adrenals, the presence of the "capsular sign" represented by a peripheral subtle hyperdense line around a hypodense enlarged adrenal, and the presence of any periadrenal inflammatory changes. All CT findings were then compared with the surgical findings (n = 5), follow-up examinations (n = 20), or autopsy (n = 4). Sensitivity, specificity, diagnostic accuracy (DA), positive predictive value (PPV), and negative predictive value (NPV) were calculated for the "capsular sign" and were further evaluated by ROC analysis. Acute adrenal ischemia occurred in 29/69 patients (42 %), unilateral in 20, and bilateral in 9. Forty of sixty-nine patients (58 %) had no evidence of adrenal disease on CT. Thrombosis of the main adrenal vein was found in 20/29 (69 %) and non-venous ischemia in 9/29 (31 %). The capsular sign was found in 24/29 patients (83 %). Sensitivity, specificity, DA, PPV, and NPV values of 83, 100, 93, 100, and 89 %, respectively, were obtained. The capsular sign represents a CT indicator of acute adrenal ischemia, with a specificity of 100 % and leading to a prompt diagnosis in the early phase of the disease.

Acute adrenal infarction as an incidental CT finding and a potential prognosis factor in severe SARS-CoV-2 infection: a retrospective cohort analysis on 219 patients

“…Edematous changes due to inflammation, reactive increase in blood flow and congestion, and small hemorrhagic foci can also result in such morphological changes. More specific imaging features of adrenal infarct were described in the literature (e.g., "capsular sign") [8] in CT exploration realized at portal venous phase or with DWI-MRI [22]. Our retrospective study included only non-enhanced chest CT performed at Emergency Department arrival to expedite patient's triage in this pandemic context.…”

“…Acute adrenal infarction (AAI) is a rare but serious complication of hypercoagulable conditions such as primary antiphospholipid antibody syndrome or pregnancy [4,5]. CT diagnosis of AAI is based on an enlargement and a low attenuation of the infarcted adrenal gland, sometimes associated with a high attenuation surrounding rim with fat stranding and "capsular sign" [6][7][8]. The incidence and potential consequences of this condition have never been evaluated in SARS-CoV-2 infection, where thromboembolic complications are frequently reported [9].…”

Pitfalls and differential diagnosis on adrenal lesions: current concepts in CT/MR imaging: a narrative review

“…Non-hemorrhagic adrenal infarction is less common and it is often caused by thrombosis of the adrenal vein, which determine parenchymal necrosis (59). It may appear on CT as a hypoattenuating area that determine a diffuse enlargement of the adrenal gland, sometimes surrounded by a peripheral subtle line of hyperenhancement (the capsular sign) (60). It is frequent to notice stranding of fat and a small amount of fluid nearby the gland (60).…”

“…It may appear on CT as a hypoattenuating area that determine a diffuse enlargement of the adrenal gland, sometimes surrounded by a peripheral subtle line of hyperenhancement (the capsular sign) (60). It is frequent to notice stranding of fat and a small amount of fluid nearby the gland (60).…”

Lower gastrointestinal bleeding due to ileocecal valve lipoma covered by an ulcerated tubular adenoma. A rare indication for surgical treatment

“…The patient was immediately supported with intravenous fluids and transfusions (RBCs) and underwent urgent gastroscopy with no evidence of bleeding. Subsequently, after stabilization she underwent colonoscopy where an ulcerated submucosal mass with an adherent thrombus was revealed in contact with the ileocecal valve and finally the patient underwent surgery with right colectomy 1 2 3 4 .…”