Whole-Body Scans are an Option

A computed tomography seems
not to be enough when diagnosing
colon cancer; © NCI Visuals Online

Determining the stage of colorectal cancer often requires a multimodality, multistep imaging approach. Complete "conventional" staging determination requires additional imaging procedures to assess potential metastatic spread to lymph nodes and solid organs. Colonography combining the imaging procedures of positron emission tomography (PET) and computed tomography (CT) provides whole-body tumour staging in a single session.

Patrick Veit-Haibach, M.D., of University Hospital Essen, Germany, and colleagues evaluated the diagnostic accuracy of whole-body PET/CT colonography for 47 patients with colorectal cancer and compared those findings with the accuracy of conventional CT staging alone and CT followed by PET (CT + PET). Patients with clinical findings and optical colonoscopy that suggested primary colorectal cancer were enrolled between May 2004 and June 2006. Patients underwent whole-body PET/CT colonography one day after colonoscopy. Fifty lesions were detected in the 47 patients.

Based on a lesion-to-lesion analysis, TNM stage (different classifications of tumour stage) was correctly determined by PET/CT colonography in 37 (74 percent) of 50 lesions and by CT alone in 26 (52 percent) of 50 lesions at a certain threshold of measurement. With CT + PET, TNM was correctly determined in 32 (64 percent) of 50 lesions. Compared with optimized abdominal CT staging alone, PET/CT colonography was more accurate in defining TNM stage (difference, 22 percent), which was mainly based on a more accurate definition of the T-stage.

Of the 47 patients, PET/CT colonography changed the therapy management in four (nine percent) compared with conventional staging. The change in patient management was based either on a more accurate assessment of the tumour stage of colorectal cancer or on accompanying findings on PET/CT colonography. This preliminary report suggests that PET/CT colonography may be at least equivalent to CT + PET with respect to tumour staging in patients with colorectal cancer,” the researchers conclude.

MEDICA.de; Source: American Medical Association