Comparison of CT, MRI and FDG-PET in response prediction of patients with locally advanced rectal cancer after multimodal preoperative therapy: is there a benefit in using functional imaging?

• Published in: European radiology 2005-08, Vol.15 (8), p.1658-1666
• Main Authors: Denecke, T, Rau, B, Hoffmann, K-T, Hildebrandt, B, Ruf, J, Gutberlet, M, Hünerbein, M, Felix, R, Wust, P, Amthauer, H
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - diagnosis; Adenocarcinoma - therapy; Cancer; Chemoradiotherapy; Colorectal cancer; Computed tomography; Female; Fluorodeoxyglucose F18; Functional magnetic resonance imaging; Histopathology; Humans; Hyperthermia; Magnetic Resonance Imaging; Male; Medical imaging; Middle Aged; Neoadjuvant Therapy; Neoplasm Staging; Positron emission; Positron emission tomography; Predictive Value of Tests; Preoperative Care; Prospective Studies; Radiopharmaceuticals; Rectal Neoplasms - diagnosis; Rectal Neoplasms - therapy; Rectum; Rectum - pathology; Sensitivity and Specificity; Tomography, X-Ray Computed; Tumors
• ISSN: 0938-7994; 1432-1084
• DOI: 10.1007/s00330-005-2658-4

The aim of this study was to compare CT, MRI and FDG-PET in the prediction of outcome of neoadjuvant radiochemotherapy in patients with locally advanced primary rectal cancer. A total of 23 patients with T3/4 rectal cancer underwent a preoperative radiochemotherapy combined with regional hyperthermia. Staging was performed using four-slice CT (n=23), 1.5-T MRI (n=10), and (18)F-FDG-PET (n=23) before and 2-4 weeks after completion of neoadjuvant treatment. Response criteria were a change in T category and tumour volume for CT and MRI and a change in glucose uptake (standard uptake value) within the tumour for FDG-PET. Imaging results were compared with those of pretherapy endorectal ultrasound and histopathological findings. Histopathology showed a response to neoadjuvant therapy in 13 patients whereas 10 patients were classified as nonresponders. The mean SUV reduction in responders (60+/-14%) was significantly higher than in nonresponders (37+/-31%; P=0.030). The sensitivity and specificity of FDG-PET in identifying response was 100% (CT 54%, MRI 71%) and 60% (CT 80%, MRT 67%). Positive and negative predictive values were 77% (CT 78%, MRI 83%) and 100% (CT 57%, MRI 50%) (PET P=0.002, CT P=0.197, MRI P=0.500). These results suggest that FDG-PET is superior to CT and MRI in predicting response to preoperative multimodal treatment of locally advanced primary rectal cancer.