PET/CT image fusion error due to urinary bladder filling changes: consequence and correction.

OBJECTIVE: A considerable change of urinary bladder (UB) shape in PET compared with CT in integrated PET/CT system is frequently noted. This study initially evaluated this finding with and without oral contrast (OC) use. In addition, a one bed pelvic section (PLV) repeat acquisition was investigated as a solution to this problem. METHODS: (18)FDG PET/CTs of 88 patients were analyzed. OC was administered in 68 patients, of whom 31 had PLV images taken 5-10 min later. Three-dimensional mid-UB CT and PET matching measurements were compared. In addition, UB walls displacement between CT and PET were analyzed. RESULTS: The mean UB height was significantly increased (P < 0.001) in PET when compared with CT, both anteriorly and posteriorly; however, UB width and depth were not significantly different. An upward shift of superior UB wall in PET from equivalent CT images was noted, whereas there was no appreciable displacement of the other UB walls. The percent UB height increase on PET from CT was significantly greater with than without OC use. The UB height difference between PET and CT was markedly reduced on PLV when compared with the original scans. CONCLUSIONS: Caution should be exerted during the interpretation of PET/CT scans of the pelvis as there is significant upward expansion of UB on PET compared with CT that appears to be exaggerated by OC use, likely due to additional fluid load. The PET/CT fusion errors of UB can be substantially resolved through a separate PLV acquisition presumably due to the shorter time interval of UB scan completion between CT and PET.

Impact of PET/CT in comparison with same day contrast enhanced CT in breast cancer management.

PURPOSE: To evaluate the impact of F-18 fluorodeoxyglucose (FDG) positron emission tomography with fused computerized tomography (PET/CT) in comparison with same day contrast enhanced CT (CE-CT) in breast cancer management. METHOD: Seventy studies in 49 breast cancer patients, 17 for initial and 53 for restaging disease were included. All patients underwent PET/CT for diagnostic purposes followed by CE-CT scans of selected body regions. PET/CT was started approximately 90 minutes following IV injection of 10-15 mCi of F-18 FDG on a GE Discovery PET/CT system. Oral contrast was given before F-18 FDG injection. The CE-CT was performed according to departmental protocol. RESULTS: Out of a total of 257 lesions, 210 were concordant between PET/CT and CE-CT. There were 47 discordant lesions, which were verified by either biopsy (35) or follow-up (12 PET positive CE-CT negative lesions). PET/CT correctly identified 25 true positive (TP). CE-CT identified 2 TP lesions missed by PET/CT which were false negatives (FNs): one liver metastasis with necrosis, which was nonavid to FDG uptake because of necrosis and a second one missed on abdominal metastatic node, which did not change staging or treatment. PET/CT incorrectly identified 2 false positive lesions while CE-CT incorrectly identified 18 false positive. TP recurrence of the disease was found by PET/CT in 44% (15/34 pts), whereas 56% (19/34 pts) were free of disease. The CE-CT described progression of the disease in 1 true negative PET/CT study and no progression in 2 TP PET/CT studies. The sensitivity, specificity, accuracy, positive productive value, and negative productive value for PET/CT were 97.8%, 93.5%, 97.3%, 99.1%, 85% and for CE-CT were 87.6%, 42%, 82.1%, 91.6%, 31.7%. CONCLUSION: In this study, PET/CT played a more important role than CE-CT scans alone and provided an impact on the management of breast cancer patients.

The distinctive role of positron emission tomography/computed tomography in breast carcinoma with brown adipose tissue 2-fluoro-2-deoxy-d-glucose uptake.

The diagnostic power of an integrated positron emission tomography/computed tomography (PET/CT) system for whole-body 2-fluoro-2-deoxy-d-glucose (FDG) imaging is clearly demonstrated in this case report. The precise anatomic localization of FDG uptake with CT in a PET/CT scan of a patient with known breast carcinoma helped identify a contralateral breast tumor with axillary lymph node metastasis despite the presence of extensive physiologic brown fat FDG uptake. Accordingly, the patient received appropriate surgical management and pathologic confirmation of the disease.