In Kook Chun

Imaging sensitivity of dedicated positron emission mammography in relation to tumor size

Positron emission mammography (PEM) has been reported to have higher sensitivity than whole-body positron emission tomography (PET)due to higher spatial resolution. However, no direct evidence exists regarding the imaging sensitivity of PEM related to lesion size. In the present study, imaging sensitivity of PEM was investigated in relation to pathologically confirmed tumor size. A total of 113 breast lesions from 101 patients were included in the analysis. The patients underwent (18)F-fluorodeoxyglucose (FDG) PEM and whole-body PET/computed tomography (CT) before surgical resection, and images were analyzed visually and quantitatively using the tumor-to-normal-tissue uptake ratio (TNR). Tumors were classified into four groups based on size using pathologic results, and sensitivities of PEM and PET/CT were compared in the overall subjects and in each size group. In visual analysis, PEM showed significantly higher imaging sensitivity than PET/CT (95% vs. 87%; P = 0.004), which was more definite in the small-tumor groups. In quantitative analysis, the TNR of PEM was significantly higher than that of PET/CT in the small-tumor groups, whereas no difference was found in the overall group. With a cutoff TNR of 2.5, PEM showed significantly higher sensitivity than PET/CT in the overall and small-tumor groups. In conclusion, PEM had higher imaging sensitivity than PET/CT, particularly in small tumors. The results suggest that PEM may be used for diagnosis and characterization of small lesions as a supplementary imaging modality for PET/CT.

Background 18F-FDG uptake in positron emission mammography (PEM): Correlation with mammographic density and background parenchymal enhancement in breast MRI

UNLABELLED We aimed to determine whether background (18)F-FDG uptake in positron emission mammography (PEM) was related to mammographic density or background parenchymal enhancement in breast MRI. METHODS We studied a total of 52 patients (mean age, 50.9 years, 26 premenopausal, 26 postmenopausal) with newly diagnosed breast cancer who underwent (18)F-FDG PEM (positron emission mammography), conventional mammography and breast MRI. The background mean (18)F-FDG uptake value on PEM was obtained by drawing a user-defined region of interest (ROI) in a normal area of the contralateral breast. We reviewed the mammography retrospectively for overall breast density of contralateral breast according to the four-point scale (grade 1-4) of the Breast Imaging Reporting and Data System (BI-RADS) classification. The background parenchymal enhancement of breast MRI was classified as minimal, mild, moderate, or marked. All imaging findings were interpreted by two readers in consensus without knowledge of image findings of other modalities. RESULTS Multiple linear regression analysis revealed a significant correlation between background (18)F-FDG uptake on PEM and mammographic density after adjustment for age and menopausal status (P<0.01), but not between background (18)F-FDG uptake on PEM and background parenchymal enhancement on MRI. CONCLUSION Background (18)F-FDG uptake on PEM significantly increases as mammographic density increases. Background parenchymal enhancement in breast MRI was not an independent predictor of the background (18)F-FDG uptake on PEM unlike mammographic density.

Pulmonary artery sarcoma detected on F-18 FDG PET/CT as origin of multiple spinal metastases.

A 67-year-old man with back pain was diagnosed as having multiple spinal metastases on MRI. On CT scan, only a filling defect in the right pulmonary artery was observed and suspected as venous thromboembolism. On F-18 fluorodeoxyglucose (FDG) PET/CT, intense hypermetabolism was observed in the right pulmonary artery in addition to the metastatic spine lesions. Biopsy confirmed the lesion as a primary pulmonary artery sarcoma (PAS), and the spine lesions as metastases of PAS. Although PAS is rare and its bone metastasis presenting initial symptom is extremely rare, FDG PET/CT is an effective diagnostic modality for PAS, not only in discrimination from venous thromboembolism, but also in workup of metastatic origin.

A Case of Enterocutaneous Fistula Diagnosed with Tc-99m DTPA Fistulography Using Hybrid SPECT/CT

Enterocutaneous fistula (ECF) is a communication between the bowel lumen and the skin, which especially occurs post-operatively and is associated with significant morbidity and mortality. Correct diagnosis and anatomical information of ECF are crucial for a patient’s management. Here, we present a case of ECF clearly diagnosed by hybrid single-photon emission computed tomography/computed tomography (SPECT/CT). A 61-year-old man was admitted to our hospital with persistent pus discharge from a surgical wound of previous cystectomy and ileal conduit formation. Initially, he was assessed with fistulography, and ECF was suspected by intraluminal contrast media. As clinical symptom and signs were not definitely matched with ECF, Tc-99m diethylene triamine pentaacetic acid (DTPA) SPECT/CT was performed for the evaluation of fistular tract as an alternative method. On the SPECT/CT after injection of Tc-99m DTPA to the putative fistular opening, fistular as well as intraluminal radioactivity was clearly visualized. SPECT/CT is a sensitive and safe diagnostic imaging tool for ECF.