Role of glucose metabolism and cellularity for tumor malignancy evaluation using FDG-PET/CT and MRI.
OBJECTIVE
Standardized uptake value (SUV) is affected by many factors. In that respect, the brain reference index (BRI: regions of interest of tumor/regions of interest of cerebellum) is one of the quantitative approaches to eliminate the variety of factors that affect SUV. MRI pulse sequence findings can also provide information about tissue cellularity. This information is useful for evaluating the malignancy of lesions. We evaluated the role of glucose metabolism and cellularity for the diagnosis of pancreatic tumor malignancy.


METHODS
We performed a radionuclide 2-(18)F-fluoro-2-deoxyglucose ((18)F-FDG) uptake analysis and a signal intensity analysis using MRI on 16 presurgery patients with either proven or suspected pancreatic cancer. The tumor glucose metabolism was evaluated with SUV and BRI in an FDG-PET study. Tumor cellularity was determined with the MRI factors, apparent diffusion coefficient (ADC), T2 value and tumor to nontumor ratio of proton density. We compared these results with the pathological findings.


RESULTS
SUV (= 0.855), BRI ( =0.875), and ADC ( =0.830) showed a larger the area under the curve than T2 value (= 0.582) and tumor to nontumor ratio of proton density ( = 0.786) according to the receiver operating characteristics analysis, and we therefore considered that these three factors were better indexes for the diagnosis of tumor malignancy. SUV and BRI had a high specificity. In contrast, ADC had a high sensitivity.


CONCLUSIONS
The glucose metabolism with PET/CT and cellularity with MRI are different indexes for the diagnosis of tumor malignancy. Both provide necessary information for making an accurate diagnosis. Using both types of information may therefore help in obtaining a highly accurate diagnosis.
Tanimoto
Katsuyuki
K
Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan. ktani@nirs.go.jp
Yoshikawa
Kyosan
K
Obata
Takayuki
T
Ikehira
Hiroo
H
Shiraishi
Takahiro
T
Watanabe
Kazuhiro
K
Saga
Tsuneo
T
Mizoe
Junetsu
J
Kamada
Tadashi
T
Kato
Atsushi
A
Miyazaki
Masaru
M
D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D004058:Diffusion; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology*; D049268:Positron-Emission Tomography; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18; D005947:Glucose