Holger Michael Strunk MD, Presenter: Nothing to Disclose

Jan Bucerius MD, Abstract Co-Author: Nothing to Disclose

Ursula Jaeger MD, Abstract Co-Author: Nothing to Disclose

Samer Ezziddin MD, Abstract Co-Author: Nothing to Disclose

Sebastian Flacke MD, Abstract Co-Author: Nothing to Disclose

Holger Palmedo MD, Abstract Co-Author: Nothing to Disclose

To evaluate the diagnostic impact of positron emission tomography (PET) with fluorine-18-labelled deoxy-d-glucose (FDG) combined with non-contrast computed tomography examinations (CT) as PET-CT modality in restaging of colorectal cancer patients.

In this prospective study, 28 consecutive patients with histologically proven colorectal cancer (14 female, 14 male, aged 51-76 years) received whole body scans in one session on a dual modality PET-CT system (Siemens Biograph) 90 min. after i.v. administration of 370 MBq 18F-FDG. The CT imaging was performed with 40mAs, 130 kV, slice-thickness 2.5 mm, pitch 1.5 and without i.v. contrast administration. PET and CT images were reconstructed with a slice-thickness of 5mm in coronal, sagittal and transverse planes. During a first step of analysis, PET and CT images were scored blinded and independently by a group of two nuclear medicine physicians and a group of two radiologists, respectively. For this purpose a three-point-scale was used. The second step of data-analysis consisted of a consensus reading by both groups. During the consensus reading, first a virtual (meaning mental) fusion of PET and CT images and afterwards the „real“ fusion (meaning coregistered) PET-CT images were also scored with the same scale. The imaging results were compared with histopathology findings and the course of disease during the further follow-up.

Total number of lesions detected in FDG-PET was n=83, in CT n=81. Lesions were classified as typical for malignancy in n=70 patiens for CT, n=71 for PET, as suspicious for malignancy n=5 for CT, n=6 for PET, as benign n=6 for CT and n=6 for PET. The results of both methods were concordant in only n=47 (56%). Comparing PET-CT and PET alone, discrepancies predominantly occured in the lung, where PET alone showed often showed false negative results and in lymph nodes and soft tissue masses, where CT often was false negative.

Combined PET/CT leads to greater accuracy in the interpretation of data and is a valuable tool for the diagnosis and anatomic localization of metastases in colorectal cancer patients.

Strunk, H, Bucerius , J, Jaeger, U, Ezziddin, S, Flacke, S, Palmedo, H, Combined FDG PET/CT Imaging for Restaging of Colorectal Cancer Patients: Impact of Image Fusion on Staging Accuracy.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4405138.html