Semi-automatic analysis of standard uptake values in serial PET/CT studies in patients with lung cancer and lymphoma

Linear regression analysis of changes in SUVmax show that intercepts and slopes are close to the line of identity for all readers (reader 1: intercept = 1.02, R2 = 0.96; reader 2: intercept = 0.97, R2 = 0.98; reader 3: intercept = 0.99, R2 = 0.98). Manual and semi-automatic method agreed in all cases whether SUVmax had increased or decreased between the serial studies. The average time to measure SUVmax changes in two serial PET/CT examinations was four to five times longer for the manual method compared to the semi-automatic method for all readers (reader 1: 53.7 vs. 10.5 s; reader 2: 27.3 vs. 6.9 s; reader 3: 47.5 vs. 9.5 s; p < 0.001 for all).Good agreement was shown in assessment of SUVmax changes between manual and semi-automatic method. The semi-automatic analysis was four to five times faster to perform than the manual analysis. These findings show the feasibility of using semi-automatic methods for calculation of SUVmax in clinical routine and encourage further development of programs using this type of methods.Changes in maximum standard uptake values (SUVmax) and computed tomography (CT) tumour size in 18FDG positron emission tomography (PET)/CT follow-up studies in oncologic patients are often assessed in tandem to determine disease progression or regression. RECIST criteria based on CT [1] are most frequently used, but criteria based on the uptake of 18FDG are receiving increasing attention [2,3]. With this, the demand for quantitative monitoring of SUV has grown as the indications for performing follow-up 18FDG PET/CT are expanding [4]. SUVmax measurements are more readily reproducible than CT sizes in both pre- and post-treatment studies [5]. Currently available PET/CT software enables the use of tools that can determine SUVmax by defining a ROI/VOI both manually and automatically within one examination. To our knowledge, none of the PET/CT manufacturers offer a software suite that can measure two matching uptakes in serial examinations automatically.T