Nagaraj Setty Holalkere MD, Presenter: Nothing to Disclose

Bindu Setty MD, Abstract Co-Author: Nothing to Disclose

Dushyant Vasudeo Sahani MD, Abstract Co-Author: Nothing to Disclose

Alan Fischman, Abstract Co-Author: Nothing to Disclose

Peter Raff Mueller MD, Abstract Co-Author: Consultant, Cook Group Incorporated, Bloomington, IN

Michael Austin Blake MBBCh, Abstract Co-Author: Nothing to Disclose

To compare the diagnostic accuracy of non-enhanced PET/CT (NE-PET/CT) and contrast enhanced PET/CT (CE-PET/CT) for detection and characterization of liver lesions in colorectal cancer.

A retrospective search of imaging database of 2004-2005 was done for PET/CT studies performed in colorectal cancer patients with suspected liver metastases. Patients with more than 10 liver lesions and those without a CE-PET/CT were excluded. Forty patients (M: F=28:12; mean age= 62 yrs) met our inclusion criteria and had liver metastases proven either by biopsy or on follow up imaging. PET/CT scans were performed on a 16-slice LSO Siemens Scanner (Biograph-16, Siemens Medical Solutions, Forchheim, Germany). Non-enhanced CT, PET and contrast enhanced CT scan were serially obtained in all the patients and NECT and CECT images were fused with PET images. The liver lesions seen on NE-PET/CT and CE-PET/CT images were characterized on an ordinal scale of 0-5 (0= absent, 1=definitely benign and 5= definitely malignant). Receiver operating characteristic (ROC) analysis was performed to compare the performance NE-PET/CT and CE-PET/CT.

A total of 130 lesions were present on follow up. The detection rate for NE-PET/CT was 74.6% (97/130) and CE-PET/CT was 92.3% (120/130). Comparative ROC analysis showed an area under curve for NE-PET/CT =0.76 (0.67-0.83), CE-PET/CT= 0.88 (0.81- 0.93) (p value = 0.002). The sensitivity, specificity, positive predictive value, negative predictive value, accuracy for characterization of liver lesions detected on NE-PET/CT and CE-PET/CT were 96.2%, 87.5%, 98.7%, 70%, 95.4% and 94%, 90%, 98.9%, 60%, 93.8% respectively. There were 12 and 7 indeterminate lesions on NE-PET/CT and CE-PET/CT respectively with 2 pseudo lesions on NE-PET/CT.

CE-PET/CT is superior to NE-PET/CT for detection of liver lesions in patients with colorectal cancer. However, both are comparable for lesion characterization.

Accurate detection and characterization of liver lesions by PET/CT helps to triage patient management. Thus, use of contrast in PET/CT could potentially be valuable for liver lesions.

Holalkere, N, Setty, B, Sahani, D, Fischman, A, Mueller, P, Blake, M, Detection and Characterization of Liver Lesions in Colorectal Cancer: A Comparative Study of Non-enhanced PET/CT and Contrast-enhanced PET/CT.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4442368.html