J Nucl Med. 2007; 48 (Supplement 2):369P
Oncology: Clinical Diagnosis-Solid Tumors
Clinical Diagnosis-Solid Tumors Posters |
Quantitative improvement in breast lesion detectability on delayed images using high resolution positron emission mammography
Lee Adler1,
Deepa Narayanan2,
Linda Gammage1,
David Beylin2 and
Rochelle Keen2
1 Adler Institute of Advanced Imaging, Jenkintown, Pennsylvania; ;
2 Research and Development, Naviscan PET Systems, Inc, Rockville, Maryland
1578
Objectives: Positron Emission Mammography (PEM) with 18F-FDG has demonstrated promise in breast cancer detection and characterization. Typically, PEM scan is performed at 60-90 min post injection, but it is known from the whole-body PET studies that delay of imaging up to 3 hours post FDG injection improves the lesion contrast, although at the same time increasing statistical noise. We sought to determine quantitatively if delayed imaging with F18-FDG using high resolution PEM would improve detectability of breast lesions. Methods: In a retrospective review of PEM patients at our facility, we examined a subset of 6 patients who were imaged at two different time points. Patients with known or suspected breast cancer were injected with an average of 13.3 mCi of 18F-FDG and PEM imaging of breast was performed with gentle compression. Bilateral breast images were acquired for 10 minutes per view with an average delay of 78 minutes (range 53-117 minutes) for initial imaging and 198 minutes (164-234 minutes) for delayed imaging. For each patient the lesion contrast and the contrast to noise ratio (CNR) was measured by drawing regions of interest on the lesions and normal background tissue on both PEM images. Results: Of the nine findings identified in five patients, there were seven pathology proven malignancies, one benign lesion and one finding pending final pathology. In one patient, scheduled for follow-up, there was no FDG abnormal uptake. In 7/7 cases of cancers, there was an average increase of 46% in CNR on delayed images; in the benign case a decrease of 4%. The background to noise ratio reduced by 33% due to increased statistical noise. Four of seven cancers were depicted only in delayed images. The maximum SUV for all cancers increased or remained the same for delayed images as compared to the initial images. Conclusions: Dual time point imaging is feasible with PEM and in this preliminary study, delayed imaging actually increased CNR in all malignancies and detected malignancies not prospectively detectable on early imaging. Larger studies of dual time point PEM are needed to define the clinical performance of this technique.
