Positron emission mammography (PEM): Effect of activity concentration, object size, and object contrast on phantom lesion detection

MacDonald, L.R.; Wang, Carolyn L.; Eissa, Marna; Haseley, David; Kelly, Mary Margaret; Liu, Franklin; Parikh, Jay R.; Beatty, J. David; Rogers, James V.

doi:10.1118/1.4754651

Cited by 10 publications

(12 citation statements)

References 32 publications

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“…Image noise versus image counts in this study followed a nonlinear trend similar to the one seen with phantom image tests (15), in which COV changes slowly for higher A eff (A eff . A STD /2), then begins to increase rapidly for lower image counts (A eff , A STD /2).…”

Section: Resultsmentioning

confidence: 51%

“…No corrections are made for scattered, attenuated, or accidental coincidence events in this system. Details of the PEM Flex hardware and performance characteristics are found in previous publications (15,18,19).…”

Section: Pem Scannermentioning

confidence: 99%

“…The first half of patients for each pathology type received an A inj of 185 MBq and a T s of 14 min, which yielded image counts equivalent to our standard PEM protocol of 370 MBq for A inj and 7 min for T s by virtue of the same A inj · T s product and scanner counting linearity (15). We refer to this as the standard injected activity (A STD ).…”

Section: Pem Scanningmentioning

confidence: 99%

“…In a previous study, we found that noise in PEM Flex images decreased only slowly as the activity concentration was increased above 2 kBq/mL, which is roughly one-half of the concentration expected in a typical patient when using the standard injection and uptake protocol (15). That study also showed a slow decrease in detection sensitivity with lowered image count density, with sensitivity remaining above 90% for a lesion diameter of 7.8 mm or more for image noise corresponding to A inj down to 100 MBq.…”

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confidence: 99%

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Positron Emission Mammography Image Interpretation for Reduced Image Count Levels

et al. 2015

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We studied the effects of reduced 18 F-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 5 0.01) and 1.9 (P 5 0.04) per doubling of image counts for 60-and 120-min uptake images, respectively, without significant difference between time points (P 5 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 5 0.02). The 120-min images had a similar trend but did not reach statistical significance (AUC 5 0.79 vs. 0.73, P 5 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. Mot ivated by remaining challenges in diagnosis, staging, and management of breast cancer, small, high-resolution PET scanners dedicated to breast imaging have been investigated since the 1990s (1-13). Dedicated breast PET systems (positron emission mammography [PEM]) have spatial resolutions better than whole-body (WB) PET scanners by factors of 2-4 and are much smaller than WB PET scanners, allowing placement of the detectors close to the breast, thus increasing geometric detection efficiency for annihilation photons relative to WB PET. In theory, increased detector efficiency allows for lower injected activities or shorter scan times while maintaining a fixed image noise level.Increased detector efficiency adds to the number of detected coincidence counts during a scan, which is the underlying metric determining inherent image noise. The activity injected into the patient (A inj ), uptake time (T up ), scan duration (T s ), and detector efficiency are the primary factors determining the number of PEM scan counts. The PEM Flex Solo II scanner (PEM Flex; CMR Naviscan) consists of 2 bar detectors (6 · 16 cm imaging area) that scan in unison along the 6-cm ...

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Section: Resultsmentioning

confidence: 51%

Section: Pem Scannermentioning

confidence: 99%

Section: Pem Scanningmentioning

confidence: 99%

mentioning

confidence: 99%

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Positron Emission Mammography Image Interpretation for Reduced Image Count Levels

et al. 2015

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“…However, limited angle reconstruction for PET data using iterative algorism may be used to produce the tomographic images. 19,20 Rotating the PET/Cerenkov-light hybrid imaging system around the subject will be another method to produce the reconstructed images for PET part of the hybrid system.…”

Section: Discussionmentioning

confidence: 99%