Visceral Adipose Tissue (fat in and around abdominal organs) has been shown to be a risk factor for all cause mortality in men. VAT is a unique, fat depot associated with metabolic risk factors (triglycerides, cholesterol, fasting glucose, hypertension) and Cardiovascular Disease. Magnetic Resonance Imaging and Computed Tomography for the quantification of VAT will be discussed, as well as slice location, spacing, and selection. The latest developments for the estimation of VAT by DXA will be covered, along with recommendations for future research and use.

1. EVOLUTION OF BONE DENSITOMETRY
NOVEL DXA USES
M h 8th, 2012
March
ISCD 2012: Los Angeles, CA
Mark Punyanitya
Biomedical Engineer

5. TYPES OF FAT
Apple shape vs. Pear shape Subcutaneous Adipose Tissue (SAT)
 S b t
Subcutaneous f t found underneath the skin,
fat f d d th th ki
which may cause dimpling and cellulite
Above the
 Fat accumulated in the lower body (the pear
waist shape) is subcutaneous
p )
Below the
waist
Visceral Adipose Tissue (VAT)
 Also known as, intra-abdominal fat, belly fat, beer
belly, central adiposity
Apple shape
 Visceral fat pads all internal vital organs such as
Pear shape
•More visceral fat •Less visceral fat stomach, kidney, heart and also pancreas
•Higher risk of weight‐ •Lower risk of weight‐
related health related health  Fat in the abdominal area (the apple shape) is
problems problems largely visceral
Source: GSK education material
S GSK d i i l
http://www.alli.co.uk/How‐alli‐works/How‐visceral‐fat‐works/  Metabolically active

7. VISCERAL ADIPOSE TISSUE (VAT)
• VAT (fat in and around
abdominal organs) has been
shown to be a risk factor for all
cause mortality in men1
• VAT is a unique pathogenic fat
unique,
depot2 associated with
metabolic risk factors
(triglycerides, cholesterol,
(triglycerides cholesterol
fasting glucose, hypertension)
and CVD
1Kuk JL, et al Visceral fat is an independent predictor of all-
cause mortality in men. Obesity. 2006;14(2):336-41.
2Fox CS, et al Abdominal visceral and subcutaneous adipose
tissue compartments: association with metabolic risk factors in
the Framingham Heart Study. Circulation. 2007 Jul 3;116(1):39-
48.

8. VISCERAL FAT AND METABOLIC RISK
Key Points
 Recent study of more than 3000
participants drawn from the
Framingham Heart Study showed
 SAT and VAT are correlated with
metabolic risk factors
 VAT more strongly associated with
an adverse metabolic risk profile
 GR = 4.7/SD (Females)
 G = 4.2/SD (
GR /S (Males)
)
.
Fox CS et al. (2007) Circulation 116 39-48

14. Visceral
Adipose
Tissue
Subcutaneous Residual
Adipose Tissue
Tissue
Tiss e Compartment

16. WHOLE-BODY
WHOLE BODY MRI ANALYSIS

20. Visceral
Adipose
Tissue
Muscle
Subcutaneous
Tissue
Adipose
Tissue
Residual
Tissue
Tiss e
Compartment

21. Visceral
Adipose
Tissue
Muscle
Tissue
Subcutaneous
Adipose
Tissue
Residual
Resid al
Tissue
Compartment

22. RELIABILITY MEASURE FOR MRI
ICC CV
Skeletal Muscle 0.99 2-5%
Subcutaneous AT 0.99 2-5%
Visceral AT
Vi l 0.95 2-5%
Intermuscular AT 0.97
0 97 5 8%
5-8%

23. SENSITIVITY MEASURE FOR MRI
MRI Baseline
ase e S of
SD o Individual
d dua G oup
Group
(kg) (mean) changes 95% CI 95% CI
(1 year) (N=20)
SM 18.6
18 6 0.40
0 40 0.82
0 82 0.19
0 19
TAT 26.8 1.00 2.06 0.47
SAT 24.0
24 0 0.90
0 90 1.85
1 85 0.43
0 43
VAT 1.9 0.20 0.41 0.09
IMAT 1.08
1 08 0.10
0 10 0.21
0 21 0.05
0 05

24. MRI Analysis
•Tissues were segmented
by trained technicians using
commercially available
image analysis software.
•Analysis time: 24 hours for
y
subcutaneous adipose
tissue, skeletal muscle,
Visceral adipose tissue,
p ,
Bone+organ, Intramuscular
adipose tissue, lung.
‐Shen W., et al., Curr Opin Clin Nutr Metab Care.
‐2006;8:595‐601

25. The % difference between Vgap and Vtrue was
generally smaller with the decrease of gap size
2 cm gap 3 cm gap 4 cm gap 5 cm gap
Acquisition 40-50 minutes 35-40 minutes 30 minutes 25 minutes
time
Analysis
a ys s 12 hours 8 hours
ou s 6 5 ou s
6.5 hours 5 hours
ou s
time
SM 0.30%±0.43% 0.41%±0.35% 0.59%±0.63% 1.04%±0.77%*
* * *
SAT 0.26%±0.23% 0.53%±0.45% 0.59%±0.49% 0.85%±0.86%*
* * *
VAT 3.14%±2.99% 5.23%±6.01% 8.14%±8.15% 9.70%±8.58%*
* * *
IMAT 3.06%±2.41% 4.75%±4.48% 6.93%±7.30% 9.55%±8.77%*
 Studies will require 2 % more subjects if every 5 cm protocol is used in 5 to 17
* * *
year old subjects and 8‐10 % more subjects in 5 to 10 year old prepubertal
children for equivalent power as the continuous every‐cm protocol in measuring
hild f i l t th ti t li i
VAT and IMAT.
‐ Shen W., et al., Int J Pediatric Obesity. 2010

26. Pearson correlations between VAT volume and
VAT areas for individual transverse slices
Correlation Coefficients
-10 cm -5 cm L4-L5 + 5 cm + 10 cm + 15 cm
Men Abdominal VAT 0.843 0.899 0.951 0.966 0.924
Abdominopelvic VAT 0.857 0.889 0.919 0.950 0.961 0.917
Women Abdominal VAT 0.908 0.929 0.972 0.961 0.822
Abdominopelvic VAT 0.856 0.930 0.936 0.964 0.951 0.821
‐ Shen W et al., Am J Clin Nutr 2004;80:271‐8

27. Group Glu Insulin TG HDL SBP DBP
Men Abdominal VAT .211 .505 .361 -.242 .312 .318
(n= 283) Abdominopelvic VAT .217 .522 .356 -.255 .309 .316
-5 cm .186 .389** .272** -.194 .244** .264
L4-L5 .193 .384** .276** -.162** .277 .266**
+5 cm .187 .458** .354 -.235 .307 .306
+10 cm
10 .210 .520 .401
.401* -.271*
.271 .306 .313
+15 cm .201 .522 .332 -.238 .295 .313
Women Abdominal VAT .218 .569 .397 -.383 -.054 .104
(n = 411) Abdominopelvic VAT .222
222 .558
558 .398
398 -.385
385 -.051
051 .110
110
-5 cm .192 .547 .386 -.386 -.072 .069
L4-L5 .161** .569 .369 -.350** -.054 .139
+5 cm .219
219 .562
562 .392
392 -.392
- 392 -.060
- 060 .076
076
+10 cm .230 .514** .385 -.348** -.062 .083
+15 cm .220 .467** .305** -.299** .013 .118
*, significantly higher (P < 0.05) than abdominal VAT; **, significantly lower (P < 0.05) than abdominal VAT.
‐Shen W., et al., Int J Obesity, 2007,31:763‐9

29. How CoreScan works
• Key Differentiator: Separates out SAT and VAT
1. Start with total fat
 iDXA distinguishes between fat, lean and bone through dual
energy measurements
 Excellent image resolution helps enable accurate tissue
characterization
2. Calculate SAT
 Utilize iDXA to measure SAT layer thickness at sides of
android region
 CoreScan maps the total SAT layer around android region
SAT inner wall
3. Total fat – SAT = VAT SAT outer wall

30. CoreScan: Reproducible
• Defined region of measurement ‐ Android
• Automated definition of region – based off
Automated definition of region – based off
bone landmarks on the body
• Consistent method of acquisition

31. CoreScan: Reproducible
Android Region
Standard region of interest for iDXA body
composition
p
Base of the ROI located at top of pelvis
Height (H) = 20% of distance from top of
pelvis to base of skull
pelvis to base of skull
Android region contains high proportion of
visceral fat
Relatively little bone in android region

32. CoreScan: Accuracy
• Validated in clinical trial*
• High degree of correlation with CT
• On average difference between iDXA
On average difference between iDXA
and CT ~60g
• 95% of subjects were within a range of CT image of visceral fat from
subject (42 year old male;
16‐96cm3 difference between measuring BMI = 26.2 kg/m2)
Image courtesy of Dr. Sanjiv Kaul
I f D S ji K l
with CT and iDXA
* Kaul et al. Dual X‐Ray Absorptiometry for Quantification of Visceral Adipose Tissue. Advance online publication 26 January 2012.

33. CoreScan: Accuracy
Analysis on OHSU Data
OHSU CT vs. iDXA VAT Volume
All Subjects
5000
Excellent Correlation*
4000
Gender SEE r2
m³)
CT VA Volume (cm
3000
Females 0.960 190.5
Males 0.953 221.6
AT
2000
Combined 0.958 209.4 1000
0
0 1000 2000 3000 4000 5000
iDXA VAT Volume (cm³)
data ID
* Kaul et al. Dual X‐Ray Absorptiometry for Quantification of Visceral Adipose Tissue. Advance online publication 26 January 2012.

34. SUMMARY
• Further studies are needed to determine
whether VF estimation offers incremental
value to other more standard measures of
metabolic and cardiovascular risk in
patients.
patients

36. VISCERAL ADIPOSE TISSUE

37. VISCERAL ADIPOSE TISSUE (VAT)
ROI DEFINITION
Regions are automatically placed by the software
•Outer region extends across entire abdomen
Outer
•Middle region extends across visceral cavity including
abdominal wall
•Inside region extends across visceral cavity just inside abdominal
wall

38. DXA VAT vs. VAT by CT
y
•Linear Relation
i l i
•High Correlation
•Low SEE vs. CT
VAT by an Expert
Reader
Micklesfield et al, Dual-Energy X-Ray Performs as Well as Clinical Computed Tomography
for the Measurement of Visceral Fat, Advance online publication 12 January 2012

39. CONCLUSION
• If these findings are supported by similar
results in other populations, DXA-VAT
may become a useful alternative to CT
and MRI for the estimation of VAT in both
clinical and research settings
settings.

40. SUMMARY OF NEW
BODY COMPOSITION FEATURES
The new VAT Application, reference values, and
reporting enhancements should be helpful in the
p g p
evaluation of a wide variety of abnormalities involving fat
mass, lean mass, and bone, for establishing entry
criteria into clinical trials and for other clinical research
trials, clinical, research,
and epidemiological uses.

50. Mark Punyanitya
Biomedical Engineer
Bi di l E i
Director, Image Reading Center
Phone: (646) 736-2487
Email: mark@imagereadingcenter.com
Web: www.imagereadingcenter.com
www imagereadingcenter com