Adherence to follow-up CT scans in patients with small pulmonary nodules, a retrospective study The Danish National guidelines have since 2008 suggested serial follow-up CT scans at 3, 6, 12, and 24 months for nodules between 5 and 10 mm and at 12 and 24 months for nodules less than 5 mm in accordance with Ellis et al. Clin Radiol 2001, 56, 691-9. As a part of our quality assurance efforts, we wanted to investigate how this follow-up proceeded - before and after the publication of the National guidelines. At our diagnostic unit we recorded 2961 cases referred for a suspected thoracic malignancy in the four year period 2006-2009. In 72 cases, 19 in 2006-2007 and 51 in 2008-2009, one or more small nodules, with diameter ≤ 10 mm, were detected on CT in patients with no known recent malignant disease. For these patients follow-up was suggested, either with CT or PET-CT. One of the 70 patients from 2008 was referred to another hospital and we have insufficient data on the follow-up. Another patient – also from 2008 -never came to the suggested first follow-up. Fifty eight patients have completed the first follow-up, while 10 are waiting for the first scheduled control CT. In twelve of the 19 patients (63 %) registered in 2006-2007 the follow-up ended after the first 3 month CT, compared to 17 of the 49 patients (33 %) in 2008-2009 (p = 0.064, Fisher’s exact test). In 28 (55 %) of all the cases registered in 2008-2009 the follow-up program was completed or on-going as planned as of February 2010. Our conclusion is that management of the follow-up of small nodules did improve in 2008-2009, but adherence to the guidelines was still limited. We will now implement a prospective program for monitoring the adherence to the follow-up CTs.