Dorela Shuboni, Christiane Mallett, Maciej Parys, and Erik Shapiro describe latest research

1. A New Magnetic Resonance Imaging Biomarker for Diabetes
Dorela Shuboni, Christiane Mallett, Maciej Parys, and Erik Shapiro
Department of Radiology, Michigan State University, East Lansing, MI
Acknowledgments:
The authors would like to thank Jeremy Hix for his
technical assistance.
Funding: NIH R01 DK107697
Contact: shubonid@msu.edu
References:
1 Diabetes Res. Clin. Pract. 103 (2014) 137. 2 PLoS ONE 10
(2015) e0120760. 3 Mol Pharm 5 (2007) 77.
General Scanning Protocol
Three groups of animals were used in the
experiment: B6.Cg-Lepob/J mice (ob/ob, n=5), a
model of mild diabetes; age matched controls
(n=5); and Oatp1a/1b cluster k/o mice (OATP
KO, n=3). Mice were each scanned three times
at 7T. After tail vein catheterization, mice
underwent DCE-MRI using a RARE sequence
(TE: 4.7 ms, TR: 200 ms, 200 μm x 200 μm) for
one hour (60 repetitions). Eovist, Multihance
or Magnevist (0.1 mmol Gd/kg) was injected
after 3 baseline images were collected.
Magnevist is a negative control.
Data Analysis
Percent enhancement was determined for the
liver and kidney at every time point by
normalization to pre-contrast enhancement.
The area under the curve (AUC) was calculated
to determine the percent clearance by organ.
The values were then statistically compared
across groups using mixed model ANOVA.
Tissue Collection and qPCR
Animals were euthanized by exsanguination
through a cardiac puncture under isoflurane.
Blood glucose was measured and organs (liver,
kidney and pancreas) were weighed and snap
frozen in liquid nitrogen. Quantitative PCR was
performed to measure OATP gene expression
in liver tissue.
Diabetes mellitus is a metabolic disorder
affecting ~10% of the US population1.
Diagnosing the disease at the pre-diabetic
stage would enable better and earlier disease
management. Organic anions transporting
polypeptides (OATPs) transport FDA-approved
Eovist and Multihance into liver. In rodent
models of Type I and Type II pre-diabetes,
animals have markedly reduced OATP levels in
the liver 2,3. Therefore, MRI may detect pre-
diabetes by monitoring contrast uptake by the
liver.
Eovist and Multihance enhanced MRI reveals
underlying alterations in OATPs that are present in the
liver as a result of diabetes. Thus, there is the potential
to monitor diabetes and perhaps even pre-diabetes by
imaging the liver, rather than the pancreas. As these
are FDA approved agents, clinical studies are straight
forward to envision.
Figure 1: Representative MR images for all groups and contrast agents.
Kidneys (K) are outlined in red and Livers (L) are outlined in blue.
Enhancement is higher in the liver of Control and ob/ob mice in Eovist and
Multihance images as compared to OATP KO row and Magnevist column.
Figure 2: Percent Enhancement across time in kidney and liver.
Control mice lines are depicted in red, OATP KO mice are blue and
ob/ob mice are green. Eovist and Multihance for the liver show
the greatest difference between experimental groups, with
Controls having higher levels than ob/ob and OATP KO mice.
Figure 3: Percent Clearance by the Liver. shows a similar pattern to
the Liver Signal Time Course with ob/ob mice having lower values for
Eovist and Multihance. a, b, c, d, and e denote groups that are
significantly different from one another, p<0.05.
Heart (%) Liver (%) Kidney (%) Pancreas (%)
Control 0.54±0.02a 3.87±0.12a 1.22±0.03a 0.63±0.07
ob/ob 0.32±0.02b 6.38±0.12b 0.73±0.04b 0.47±0.09
OATP 0.52±0.01a 5.07±0.24c 1.68±0.03c 0.72±0.06
Figure 4: Blood Glucose Levels. show that Control and OATP KO
mice have significantly higher levels of blood glucose. a, b and c
denote groups that are significantly different from one another,
p<0.05.
Table 1. Percent mass of organs by total mass of mouse. One-way ANOVA by organ,
different letters (a,b and c) represent significant difference between mouse
phenotype, p<0.05.
qPCR Results: In a subset of animals, ob/ob:4; Control:2, qPCR
demonstrated a 12.75±0.95X decrease in OATP1A1 expression
for ob/ob mice. Using Eovist and Multihance, ob/ob mice had
reduced and delayed uptake in the liver and increased levels
within the kidney
LBAP057