Doctors may be able to better evaluate the stage of colorectal cancer using a technique that combines two imaging systems used to make a 3-D image of the whole body, a new study suggests.
The technique combines whole-body positron emission tomography (PET) and computed tomography (CT) scans to obtain better information as to tumor location, size, and grade within the colon in a single imaging session. The study, led by Dr. Patrick Veit-Haibach, of University Hospital Essen, Germany, appears in the Dec. 6 issue of the Journal of the American Medical Association.
Exact and complete information on the stage of the tumor is of great benefit to patients, but determining the stage of colorectal cancer often requires multiple imaging studies done in multiple sessions, adding time and cost to cancer assessment.
“This preliminary report suggests that PET/CT colonography may be at least equivalent to CT plus PET with respect to tumor staging in patients with colorectal cancer,” the authors wrote. “It is less time-consuming than a conventional multistep approach with CT alone (abdomen and thorax) and PET imaging if required. Thus, it represents a psychological and physical advantage when considering the burden to the patient of different imaging procedures.”
The technique also benefits the physician by producing a single report including complete tumor staging in a single step, enabling him/her to define further therapy, the authors wrote.
The technique, called PET/CT colonography, combines the imaging procedures of positron emission tomography (PET) and computed tomography (CT) in a whole-body tumor staging in a single session.
In the study, patients who were thought to have colon or rectal cancer based on a colonoscopy were enrolled between May 2004 and June 2006. Patients underwent whole-body PET/CT colonography 1 day after colonoscopy. A total of 50 lesions were detected in the 47 patients.
Using single-step PET/CT colonography the researchers correctly determined the tumor stage in 37 (74 percent) of the 50 lesions compared to correctly determining stage using CT alone in 26 patients (52 percent). Using the multi-step CT scan followed by PET, they correctly determined the stage in 32 (64 percent) of 50 lesions.
Of the 47 patients, the single-step PET/CT colonography changed the therapy management in 4 patients (9 percent) compared with conventional staging. The change in patient management was based either on a more accurate assessment of the tumor stage of colorectal cancer or on accompanying findings on PET/CT colonography.