Nucl Med Mol Imaging.  2016 Jun;50(2):150-156. 10.1007/s13139-015-0390-9.

Correlation Between Apparent Diffusion Coefficients and Standardized Uptake Values in Hybrid 18F-FDG PET/MR: Preliminary Results in Rectal Cancer

• Jeong JH
• Cho IH
• Chun KA
• Kong EJ
• Kwon SD
• Kim JH

• KMID: 2257003
• DOI: http://doi.org/10.1007/s13139-015-0390-9

Abstract

PURPOSE
Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWI) share the same role in clinical oncology and it is feasible to obtain the standardized uptake value (SUV) and apparent diffusion coefficient (ADC) simultaneously by emerging the hybrid positron emission tomography/magnetic resonance (PET/MR). This study investigated the correlation between the ADCs of rectal cancer lesions and their SUVs derived from hybrid PET/MR.
METHODS
Nine patients with histologically proven rectal adenocarcinoma (5 men, 4 women; mean age, 70±15.91 years) underwent torso 18F-FDG PET/CT and regional hybrid 18F-FDG PET/MR sequentially. A fixed threshold value of 40% of maximum uptake was used to determine tumor volume of interest (VOI) on PET image; SUVmax, SUVpeak, and SUVmean were calculated automatically. A single freehand region of interest (ROI) was drawn on high b-value (b1000) DWI image and copied to corresponding ADC map to determine the ADCmean of rectal cancer lesion. Spearman's rank correlation coefficient (ρ) was calculated to determine the correlation between SUVs and ADC values.
RESULTS
SUVmax, SUVpeak, and SUVmean derived by hybrid PET/MR were 12.35 ± 4.66 (mean ± standard deviation), 9.66 ± 3.15 and 7.41 ± 2.54, respectively. The ADCmean value of rectal cancer lesions was 1.02 ± 0.08 × 10-3mm2/s. ADCmean was significantly and inversely correlated with SUV values (SUVmax, ρ = -0.95, p < 0.001; SUVpeak, ρ = -0.93, p < 0.001; SUVmean, ρ = -0.91, p = 0.001).
CONCLUSIONS
This preliminary hybrid PET/MR study demonstrates a significant inverse correlation exists between metabolic activity on 18F-FDG PETand water diffusion on DWI in rectal cancer.

Keyword

Diffusion magnetic resonance imaging; Fluorodeoxyglucose F18; Multimodal Imaging; Positron-emission tomography; RectalNeoplasms

MeSH Terms

Adenocarcinoma
Diffusion Magnetic Resonance Imaging
Diffusion*
Electrons
Female
Fluorodeoxyglucose F18*
Humans
Magnetic Resonance Imaging
Male
Medical Oncology
Multimodal Imaging
Positron-Emission Tomography
Positron-Emission Tomography and Computed Tomography
Rectal Neoplasms*
Torso
Tumor Burden
Water
Fluorodeoxyglucose F18
Water