AIM: To determine the prevalence of unsuspected thyroid nodules on contrast enhanced 16and 64-modified discrete cosine transform (MDCT) of the chest, in a population of adult outpatients imaged for indications other than thyroid disease. METHODS: This retrospective study involved review of intravascular contrast-enhanced MDCT scans of the chest from 3077 consecutive adult outpatients, to identify unsuspected thyroid nodules. Exclusion criteria included history of thyroid cancer, known thyroid nodules or thyroid disease and risk factors for thyroid cancer, as evidenced by their medical records. One of 9 radiologists recorded number of nodules, location and bidirectional measurement of largest nodule, as well as amount of thyroid visualized on the chest computed tomography (CT). Presence of nodule was correlated with age, gender, race and percentage of thyroid imaged. RESULTS: A total of 2510 (2510/3077 or 81.6%) study subjects were included in the data analysis; among them,one or more nodules were identified in 629 subjects (629/2510 or 25.1%), with 242 (242/629 or 38.5%) having multiple nodules. Patients with nodule(s) were significantly older than those without (64 ± 13 years vs 58 ± 14 years, P < 0.0001), and female gender was associated with presence of nodule(s) (373/1222 or 30.5% vs 256/1288 or 19.9%, P < 0.0001). Women were also more likely having multiple nodules (167/373 or 44.8%) compared to men (75/256 or 29.3%, P < 0.0001). The majority of nodules (427/629 or 67.9%) were less than 1 cm. CONCLUSION: This retrospective review revealed a prevalence of 25.1% for unsuspected thyroid nodules on contrast-enhanced chest CT. AIM: To determine the prevalence of unsuspected thyroid nodules on contrast enhanced 16 and 64-modified discrete cosine transform (MDCT) of the chest, in a population of adult outpatients imaged for indications other than thyroid disease. METHODS: This retrospective study involved review of intravascular contrast-enhanced MDCT scans of the chest from 3077 consecutive adult outpatients, to identify unsuspected thyroid nodules. Exclusion criteria included history of thyroid cancer, known thyroid nodules or thyroid disease and risk factors for thyroid cancer, as evidenced by their medical records. One of 9 radiologists recorded number of nodules, location and bidirectional measurement of largest nodule, as well as amount of thyroid visualized on the chest computed tomography (CT). Presence of nodule was correlated with age, gender, race and percentage of thyroid imaged. RESULTS: A total of 2510 (2510/3077 or 81.6%) study subjects were included in the data analysis; among them, one or more n Patients with nodules (s) were significantly older than those without (64 ± 13 years vs 58 ± 14 (629/2510 or 25.1%), with 242 (242/629 or 38.5% years, P <0.0001), and female gender was associated with presence of nodules (373/1222 or 30.5% vs 256/1288 or 19.9%, P <0.0001). Women were also more likely having multiple nodules (167 / 373 or 44.8%) compared to men (75/256 or 29.3%, P <0.0001). The majority of nodules (427/629 or 67.9%) were less than 1 cm. CONCLUSION: This retrospective review revealed a prevalence of 25.1% for unsuspected thyroid nodules on contrast-enhanced chest CT.