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More accurate imaging aids in determining tumor stage
Source: (cancerfacts.com)
Friday, January 02, 2004
CHICAGO – Jan. 2, 2004 – A new study suggests that a whole-body, computer-aided imaging technique may be more useful than whole-body MRI for determining the extent of cancer spread in patients with advanced cancers.
The technique combines positron emission tomography (PET) with computed tomography (CT) to produce a three-dimensional x-ray showing the location of tumors throughout the body.
In a study of 98 patients led by Dr. Gerald Antoch of the University Hospital Essen, Germany, the researchers compared the staging accuracies of whole-body PET-CT and whole-body MRI for different malignant diseases. The results appear in the Dec. 24-31 issue of The Journal of the American Medical Association (JAMA).
"The most crucial aspect of clinical tumor staging relates to the staging impact on patient management," the authors wrote. "Compared with MRI, PET-CT had a direct impact on patient management in 12 patients while MRI changed the therapy regimen in 2 patients. Separate assessment of tumor-stage (with pathological verification) in 46 patients revealed PET-CT to be accurate in 37 (80 percent) of the patients and MRI to be accurate in 24 (52 percent) of patients."
The study included 98 patients with an average age of 58 years; (range, 27-94 years) with various cancers who underwent back-to-back whole-body PET-CT and whole-body MRI for tumor staging. The study was conducted at a university hospital from Dec. 2001 through Oct. 2002 and had an average follow-up of 273 days (range, 75-515 days). The images were evaluated by two different teams of radiologists, who compared the diagnostic accuracies of the two imaging procedures.
The researchers found that of the 98 patients, the overall primary tumor, regional lymph nodes, and distant metastasis (TNM) stage was correctly determined in 75 patients (77 percent) with PET-CT and in 53 patients (54 percent) with MRI.
Lymph node involvement was correctly determined in 91 patients (93 percent) with PET-CT and in 77 patients (79 percent) with MRI Both imaging procedures showed a similar performance in detecting tumors located in parts of the body distant from the original tumor (distant metastases).
In malignant diseases, therapeutic options as well as the patients' prognoses strongly depend on the tumor stage. Thus, accurate tumor staging encompassing the entire body is of essential importance. Magnetic resonance imaging (MRI) and a combined modality including PET-CT provide means for whole-body tumor staging in a single session.
In contrast to MRI, which is mainly focused on the assessment of structural characteristics of tissue, positron emission tomography using a dye injected into the body (FDG-PET) provides functional information on tumor metabolism. The functional data available in whole-body scans complement structural imaging for staging different malignancies.
CT imaging is the process of using digital processing to generate a three-dimensional image of an internal section of the body from a series of two-dimensional x-ray images. MRI involves application of an external magnetic field to produce three-dimensional images of body tissues.
In an accompanying editorial, Drs. Lennart Blomqvist, and Michael R. Torkzad, of the Karolinska Hospital, Stockholm wrote, "The day in which futuristic movies show a patient lying on a table, entering a tunnel-like device with blinking lights, only to return a few moments later with a rapid diagnosis and a specific treatment plan, does not seem as far away as once thought."
SOURCE: JAMA 2003; 290:3199-3206
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