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Updated: Apr 30, 2026
Multianimal Magnetic Resonance Imaging for Tumor Measurements in Pancreatic Cancer Mouse Models
Published on: February 3, 2026
Variability of target and normal structure delineation using multimodality imaging for radiation therapy of
Entesar Dalah1, Ion Moraru1, Eric Paulson2
1Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin.
Purpose:
To explore the potential of multimodality imaging (dynamic contrast-enhanced magnetic resonance imaging [DCE-MRI], apparent diffusion-coefficient diffusion-weighted imaging [ADC-DWI], fluorodeoxyglucose positron emission tomography [FDG-PET], and computed tomography) to define the gross tumor volume (GTV) and organs at risk in radiation therapy planning for pancreatic cancer. Delineated volumetric changes of DCE-MRI, ADC-DWI, and FDG-PET were assessed in comparison with the finding on 3-dimensional/4-dimensional CT with and without intravenous contrast, and with pathology specimens for resectable and borderline resectable cases of pancreatic cancer.
Methods And Materials:
We studied a total of 19 representative patients, whose DCE-MRI, ADC-DWI, and FDG-PET data were reviewed. Gross tumor volume and tumor burden/active region inside pancreatic head/neck or body were delineated on MRI (denoted GTVDCE, and GTVADC), a standardized uptake value (SUV) of 2.5, 40%SUVmax, and 50%SUVmax on FDG-PET (GTV2.5, GTV40%, and GTV50%). Volumes of the pancreas, duodenum, stomach, liver, and kidneys were contoured according to CT (VCT), T1-weighted MRI (VT1), and T2-weighted MRI (VT2) for 7 patients.
Results:
Significant statistical differences were found between the GTVs from DCE-MRI, ADC-DW, and FDG-PET, with a mean and range of 4.73 (1.00-9.79), 14.52 (3.21-25.49), 22.04 (1.00-45.69), 19.10 (4.84-45.59), and 9.80 (0.32-35.21) cm(3) for GTVDCE, GTVADC, GTV2.5, GTV40%, and GTV50%, respectively. The mean difference and range in the measurements of maximum dimension of tumor on DCE-MRI, ADC-DW, SUV2.5, 40%SUVmax, and 50%SUVmax compared with pathologic specimens were -0.84 (-2.24 to 0.9), 0.41 (-0.15 to 2.3), 0.58 (-1.41 to 3.69), 0.66 (-0.67 to 1.32), and 0.15 (-1.53 to 2.38) cm, respectively. The T1- and T2-based volumes for pancreas, duodenum, stomach, and liver were generally smaller compared with those from CT, except for the kidneys.
Conclusions:
Differences exists between DCE-, ADC-, and FDG-PET-defined target volumes for RT of pancreatic cancer. Organ at risk volumes based on MRI are generally smaller than those based on CT. Further studies combined with pathologic specimens are required to identify the optimal imaging modality or sequence to define GTV.
