PT  - JOURNAL ARTICLE
AU  - MacDonald, Lawrence R.
AU  - Hippe, Daniel S.
AU  - Bender, Leila C.
AU  - Cotter, Elizabeth W.
AU  - Voria, Pooja R.
AU  - Hallam, Paula S.
AU  - Wang, Carolyn L.
AU  - Haseley, David R.
AU  - Kelly, Mary M.
AU  - Parikh, Jay R.
AU  - Beatty, J. David
AU  - Rogers, James V.
TI  - Positron Emission Mammography Image Interpretation for Reduced Image Count Levels
AID  - 10.2967/jnumed.115.165787
DP  - 2016 Mar 01
TA  - Journal of Nuclear Medicine
PG  - 348--354
VI  - 57
IP  - 3
4099  - http://jnm.snmjournals.org/content/57/3/348.short
4100  - http://jnm.snmjournals.org/content/57/3/348.full
SO  - J Nucl Med2016 Mar 01; 57
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.