FLUORODEOXYGLUCOSE WHOLE-BODY POSITRON-EMISSION-TOMOGRAPHY IN COLORECTAL-CANCER PATIENTS STUDIED IN ROUTINE DAILY PRACTICE

PURPOSE: To evaluate the routine clinical value of attenuation-correct ed whole-body fluorodeoxyglucose positron emission tomography in color ectal cancer, a total of 59 patients who were referred for evaluation of suspected or proven colorectal cancers were studied. METHODS: Posit ron emission tomography scans were recorded using a Siemens ECAT Exact 921/47. RESULTS: Median follow-up after the positron emission tomogra phy study was 11 (mean, 12.3; range, 1-21) months. According to comput ed tomography, coloscopy, and ultrasound, we recorded eight apparently false-positive results. During later follow-up, however, three of tho se cases, which were negative with computed tomography, magnetic reson ance imaging, sonography, or laparoscopy, turned out to be true-positi ve instead. In 3 patients, a primary colorectal cancer was suspected; in 26 patients, a recurrence of colorectal cancer was suspected. Eight patients were studied for follow-up after the history of colorectal c ancer with no suspicion of recurrence. In 12 patients, the rise of ser um tumor marker concentrations was the reason for the positron emissio n tomography study; 12 patients with known metastatic disease were als o included (''restaging''). With regard to the entire patient populati on, we found an overall sensitivity of 100 percent, a specificity of 6 7 percent, and positive and negative predictive values of 92 and 100 p ercent, respectively. Being merely confirmative with respect to tumor recurrence or distant metastases in the majority of patients, positron emission tomography revealed a primary tumor in one patient and confi rmed metastatic foci in several patients that had not been delineated by other imaging modalities. CONCLUSION: A whole-body positron emissio n tomography scan provides optimum conditions to locate metastatic les ions that might not be seen otherwise. There is a trend showing that p ositron emission tomography diagnostics as a consequence of early incr eased tumor markers is a highly sensitive combination, because compute d tomography and magnetic resonance imaging were not as sensitive in e arly recurrences. Positron emission tomography, as performed in daily clinical practice, proved to be a powerful diagnostic tool in our subs et of colorectal cancer patients.