RT Journal Article SR Electronic T1 Positron Emission Mammography Image Interpretation for Reduced Image Count Levels JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 348 OP 354 DO 10.2967/jnumed.115.165787 VO 57 IS 3 A1 Lawrence R. MacDonald A1 Daniel S. Hippe A1 Leila C. Bender A1 Elizabeth W. Cotter A1 Pooja R. Voria A1 Paula S. Hallam A1 Carolyn L. Wang A1 David R. Haseley A1 Mary M. Kelly A1 Jay R. Parikh A1 J. David Beatty A1 James V. Rogers YR 2016 UL http://jnm.snmjournals.org/content/57/3/348.abstract AB We studied the effects of reduced 18F-FDG injection activity on interpretation of positron emission mammography (PEM) images and compared image interpretation between 2 postinjection imaging times. Methods: We performed a receiver-operating-characteristic (ROC) study using PEM images reconstructed with different count levels expected from injected activities between 23 and 185 MBq. Thirty patients received 2 PEM scans at postinjection times of 60 and 120 min. Half of the patients were scanned with a standard protocol; the others received one-half of the standard activity. Images were reconstructed using 100%, 50%, and 25% of the total counts acquired. Eight radiologists used a 5-point confidence scale to score 232 PEM images for the presence of up to 3 malignant lesions. Paired images were analyzed with conditional logistic regression and ROC analysis to investigate changes in interpretation. Results: There was a trend for increasing lesion detection sensitivity with increased image counts: odds ratios were 2.2 (P = 0.01) and 1.9 (P = 0.04) per doubling of image counts for 60- and 120-min uptake images, respectively, without significant difference between time points (P = 0.7). The area under the ROC curve (AUC) was highest for the 100%-count, 60-min images (0.83 vs. 0.75 for 50%-counts, P = 0.02). The 120-min images had a similar trend but did not reach statistical significance (AUC = 0.79 vs. 0.73, P = 0.1). Our data did not yield significant trends between specificity and image counts. Lesion-to-background ratios increased between 60- and 120-min scans (P < 0.001). Conclusion: Reducing the image counts relative to the standard protocol decreased diagnostic accuracy. The increase in lesion-to-background ratio between 60- and 120-min uptake times was not enough to improve detection sensitivity in this study, perhaps in part due to fewer counts in the later scan.