BACKGROUND: Current indications for adrenalectomy include functional adrenal tumors and potentially malignant tumors based on imaging studies. We evaluated the effectiveness of magnetic resonance imaging (MRI) in obtaining a correct preoperative diagnosis. METHOD: Fifty-three patients with nonfunctional adrenal lesions were analyzed. Indications for adrenalectomy of nonfunctional adrenal lesions included >6 cm in size and ≤6 cm in size with atypical characteristics on MRI. Lesions with a size of >6 cm, local invasion, irregular margins, and chemical-shift imaging that demonstrated no loss of signal intensity on out-of-phase images were considered suspected of malignancy. RESULTS: Adrenal lesions of >6 cm in size exhibited an 80-fold increased prediction of malignancy (OR: 80; 95% CI 7.8-813), whereas irregular margins and local invasion exhibited a 45-fold (OR: 45; 95% CI 6.4-312.5) and a 12-fold (OR: 12; 95% CI 4.6-30.6) increased occurrence of malignancy, respectively. The loss of signal intensity did not affect the prediction of malignancy. CONCLUSION: The rate of unnecessary tumor resections that are <6 cm in size can be decreased by performing adrenal biopsies in selected cases or by short-term follow-up to prevent the insufficiency of imaging techniques.
BACKGROUND: Current indications for adrenalectomy include functional adrenal tumors and potentially malignant tumors based on imaging studies. We evaluated the effectiveness of magnetic resonance imaging (MRI) in obtaining a correct preoperative diagnosis. METHOD: Fifty-three patients with nonfunctional adrenal lesions were analyzed. Indications for adrenalectomy of nonfunctional adrenal lesions included >6 cm in size and ≤6 cm in size with atypical characteristics on MRI. Lesions with a size of >6 cm, local invasion, irregular margins, and chemical-shift imaging that demonstrated no loss of signal intensity on out-of-phase images were considered suspected of malignancy. RESULTS: Adrenal lesions of >6 cm in size exhibited an 80-fold increased prediction of malignancy (OR: 80; 95% CI 7.8-813), whereas irregular margins and local invasion exhibited a 45-fold (OR: 45; 95% CI 6.4-312.5) and a 12-fold (OR: 12; 95% CI 4.6-30.6) increased occurrence of malignancy, respectively. The loss of signal intensity did not affect the prediction of malignancy. CONCLUSION: The rate of unnecessary tumor resections that are <6 cm in size can be decreased by performing adrenal biopsies in selected cases or by short-term follow-up to prevent the insufficiency of imaging techniques.