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PURPOSE: To validate the diagnostic performance of adrenal washout CT in patients without known malignancy in a Western Australian population. METHODS: A radiology information system (RIS) search for CT reports containing "adrenal" and "washout" across six networked metropolitan public hospitals between January 2005 and November 2021. Homogenous nodules ≥ 1 cm, ≥ 10 HU without a suspected functional component in patients without a history of malignancy were included. Reported absolute and relative washout percentages were recorded and re-measured from unenhanced, 60-s portal venous and 15-min delayed phase imaging and compared to either histopathological or CT follow up for growth (≥ 12 months) reference standards. RESULTS: 2653 studies were screened with 191 meeting inclusion criteria. 105 nodules underwent washout CT and then had either histopathological (12 patients) or CT follow up (93 patients) reference standards available. Reported absolute washout (aWO) estimated sensitivity and specificity for malignant/indeterminate nodules was low at 33% (95% CI 25-43%) and 77% (95% CI 68-84%) respectively. Reported relative washout (rWO) sensitivity and specificity were 56% (95% CI 46-65%) and 69% (95% CI 60-77%) respectively. Negative predictive values for both aWO and rWO were reassuring at 92% (95% CI 86-96%) and 94% (95%CI 88-97%). CONCLUSION: Our study validates a recent report suggesting that adrenal washout has poor sensitivity for and consequent limited utility to exclude malignancy in patients with no cancer history. However, patients with incidental adrenal nodules < 4 cm in size with benign washout can be reassured by the high negative predictive value and worked up to exclude functional adenoma and re-imaged in a year to confirm no growth.
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INTRODUCTION: The os intermetatarseum is an uncommon accessory ossicle of the foot located dorsally, between the bases of the first and second metatarsals that are usually asymptomatic. In the setting of trauma, this ossicle can clinically mimic a Lisfranc fracture-dislocation, a potentially disabling condition often requiring surgical intervention. METHODS: In this study, 47 cases of os intermetatarseum were reviewed across several Western Australian (WA) Hospitals and characterised based on morphology. Any fractures were recorded, and their cases were reviewed. RESULTS: The most common type of os intermetatarseum was freestanding at 63%, followed by the articulating type at 30%. Only 7% were of the fused type. Two acute fractures were identified on plain radiography and computed tomography (CT). CONCLUSION: The distribution of os intermetatarseum subtypes in the WA population is consistent with previous radiological studies. The two cases of isolated acute os intermetatarseum fracture are described, the first to our knowledge, highlighting the need for increased awareness of this ossicle in the setting of foot trauma.