Researchers from the University of Düsseldorf found that PET/MRI achieved accuracy of 93%, compared with 88% for DWI-MRI. PET/MRI also reached sensitivity of 72%, compared with 36% for DWI-MRI.
Lymph node status has prognostic value in head and neck cancer because patients with metastases need neck dissection and adjuvant treatment. Therefore, precise lymph node staging is a necessity, noted lead author Christian Buchbender, MD.
“Currently available imaging modalities are restricted in their diagnostic performance for lymph node metastases detection,” he added. “For example, CT and MRI fall short in sensitivity when compared to FDG-PET or FDG-PET/CT. On the other hand, FDG-PET/CT suffers from a large amount of false-positive results.”
Thus, new modalities or a combination of modalities are needed to improve lymph node metastases detection in these cancer patients, he said.
The prospective study included 14 head and neck cancer patients with a mean age of 67 years. Prior to surgery, the patients received both FDG-PET/CT and 3-tesla MRI, including diffusion-weighted imaging. The patients then underwent bilateral neck dissection.
Using image fusion software, the researchers created two sets of images. One set consisted of PET/MR images, which were created by fusing FDG-PET results with contrast-enhanced, T1-weighted, fat-saturated MR images. The second set consisted of DWI-MR images, created by fusing DWI results with T1-weighted, fat-saturated MR images.
Buchbender and colleagues then analyzed both sets of images for the presence of lymph node metastases and found that PET/MRI detected 26 (93%) of 28 lymph node metastases, compared with 20 (71%) detected by DWI-MRI.
“When we compared these results to available data on PET/CT, we found that PET/MRI pretty much equals the performance of PET/CT,” Buchbender added.
