Purpose: Evaluate the diagnostic performance of contrast enhanced CT/PET (ceCT/PET) in the response assessment of patients with colorectal cancer liver metastases.
Methods: 33 ce CT/PET studies of 19 patients with colorectal liver metastases were prospectively evaluated. All of them, 13 (68.4%) were males and 6 (31.6%) females. Mean age and range were 63 [42-78]. All patients were treated with neoadjuvant chemotherapy. In all cases post-therapy diagnostic confirmation of liver lesions was obtained. A ce CT PET/was obtained 1h after the injection of 370 MBq of 18F-FDG. Metabolic and morphologic studies were evaluated by two blinded nuclear physicians and radiologists respectively to assess the location, size and suspected diagnosis of lesions (benign or malignant). A combined assessment of both techniques was performed. The final diagnosis was established by histopathology or clinical/radiological follow-up greater than 6 months.
Results: A total of 120 liver lesions were identified, 115 were malignant and 5 benign. From the malignant lesions, 105 were identified with the ceCT, 44 with the PET and 109 with ceCT/PET. All of the benign lesions were correctly classified with any of the three imaging techniques. The sensitivity of PET, ceCT and ceCT/PET were of 38%, 91% and 95% respectively and the specificity was 100% in all three of the diagnostic studies.
Conclusion: Administration of intravenous contrast in the PET/CT is mandatory to evaluate treatment response rate of liver metastases due to the limitations of isolated metabolic images in these cases.
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