18F-FLT-PET for detection of rectal cancer

Abstract

Purpose: This pilot study was undertaken to examine the ability of (18)F-3'-fluoro-3'-deoxy-l-thymidine positron emission tomography ((18)F-FLT-PET)to detect rectal cancer, to identify pathologic lymph nodes and to determine the accuracy of tumour length estimation in comparison with computer tomography (CT).

Methods: Nine patients with biopsy proven rectal cancer underwent CT and (18)F-FLT-PET scanning prior to short-term pre-operative radiotherapy (5×5Gy). Within 10 days after the start of radiotherapy a surgical resection was performed. Tumour lengths and regional lymph node visualisation on both imaging modalities were compared with pathology findings.

Results: All tumours were visible on CT. (18)F-FLT-PET visualised 7 out of 9 tumours (78%). The pathology-based tumours lengths correlated better with CT as compared to FLT-PET(r=0.91, p<0.01). (18)F-FLT-PET was not able to visualise pathologic lymph nodes. However, CT identified all patients with pathologic lymph nodes.

Conclusion: Primary rectal cancer can be visualised by (18)F-FLT-PET in the majority of cases but not in all. However, (18)F-FLT-PET was not able to identify pathologic lymph nodes. Therefore, we conclude that (18)F-FLT-PET has limited value for the detection of pathologic lymph nodes and tumour delineation in rectal cancer.