Download Low Contrast Volume Abdominal CTA

Constantino S. Pena, MD: Low contrast volume
abdominal CTA
May 15, 2008- 3:20 PM
Low Contrast Volume
Abdominal CTA
All Iodinated contrast media sold in
the US are not approved for CTA by
the FDA
Constantino S. Peñ
Peña, M.D.
Interventional Radiologist
Director of Vascular Imaging
The Journey to MDCT
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All Gadolinium contrast media sold in
the US are not approved for MRA by
the FDA
MDCT technology has provided the coverage to
allow development of CT Angiography
Single helical scanners 1989
4-Slice scanners 1999
16 Slice scanners 2002
64 slice scanners 2004
256 slice/ 320 slice scanners 2008
Continuous patient motion
in order to allow the
imaging the ability to
follow a contrast bolus
through
h
h an iimaging
i
volume.
• Allows more longitudinal coverage with each
rotation
• Slow pitch (multiple thinly collimated images)
Post processing
techniques allowed for the
evaluation of the vessels
in multiple projections.
Ideal Imaging Time
Contrast Optimization
Patient’s
Cardiac Output
Rate of Injection
Contrast Volume
Enhan
cement
Iodine
Concentration
IODINE FLUX
Stanford Radiology 10th Annual Multidetector
CT Symposium
Time
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Constantino S. Pena, MD: Low contrast volume
abdominal CTA
May 15, 2008- 3:20 PM
Abdominal CTA
„
CTA is the study of choice to evaluate aortoiliac
segments-- Inflow vessels
segments
Reliable and reproducible
„ High spatial resolution
„ Assessment of calcium and non calcified plaque
„ Not directly visualized with ultrasound
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Indication for both occlusive disease and
aneurysmal disease
Why can we use less contrast?
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Have we used reduced contrast
volumes before?
Why Reduce Contrast Use?
„
Decrease the risk of contrast induced nephropathy
Higher CIN rates in patients receiving more than 100
mls of contrast
„ Many patients receive a multiple contrast enhanced
scans within several days of hospitalization
„ Cost
Faster scanning volumes
Greater spatial and temporal resolution
Better ability to follow the bolus (speed of
scanner))
Ability to give a compact contrast bolusbolus- better
injectors and injection protocols (CT PICC
lines)
Ability to follow bolus with saline
YES
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Can we reduce the amount of contrast
media injected without decreasing
contrast enhancement?
Gadolinium CTA (usually triple dosedose- < 60mls)
Used routinely prior to NSF
Used in patients with renal insufficiency unable
to tolerate MR, those necessitating the spatial
resolution of CT but unable to receive contrast
(allergy or renal insufficiency)
MDCTPA with Gadolinium
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Gadolinium Chelate; 3cc/sec;120kv
Stanford Radiology 10th Annual Multidetector
CT Symposium
60 pts; 16 detector scanner
Iodine allergy and/or renal insufficiency
0.3 or 0.4 mmol/kg; at 6ml/sec dual phase
Threshold triggering 50 HU
80--10080
100-120 kV
Remy-Jardin, Behapar, et al. Radiology 2006; 238:1022-1035.
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Constantino S. Pena, MD: Low contrast volume
abdominal CTA
May 15, 2008- 3:20 PM
Patients Studied
„
45 patients (72 + 6 years) undergoing abdominal
pelvic CTA
22 patients underwent 50 mls protocol
23 patients
i
underwent
d
100mls
100 l protocoll
„
22 patients (10/12) had EVAR
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Methods
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All patients on same Philips Brilliance 64 CT
scanner
18 gauge IV using multiphase injector
R l time
Real
i b
bolus
l tracking
ki triggering
i
i iin the
h
proximal aorta
22 patients (10/12) had EVAR
Image quality
Methods
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Contrast injected at 3.5mls/sec
Saline flush at 3.5cc/sec for 30 cc
Bolus trigger in the proximal aorta at 200 HU
6 second delay before scanning
Pitch at 50 cccc- 0.89 with 0.75 sec rotation
Pitch at 100cc 0.89 with a 1 sec rotation
0.625mm x 64 detector, 140 KvP, 400mA
Image quality
Reduced contrast dose
64-detector CTA in a 72-year-old male with a 55 mm AAA
using 100 ml of contrast medium.
Arterial attenuation: 201.5 Hounsfield units
Stanford Radiology 10th Annual Multidetector
CT Symposium
82-year-old female with a 48 mm abdominal aortic
aneurysm using 50 ml of contrast medium.
Arterial attenuation: 195.7 Hounsfield units
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Constantino S. Pena, MD: Low contrast volume
abdominal CTA
Image Evaluations
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May 15, 2008- 3:20 PM
69 yo F AAA EvaluationEvaluation- 50mls
Quantitatively via ROI in 8 locations
Qualitatively using three reviewers
No significant difference in attenuation between the groups
What we do not know?
89 YO Diabetic S/P EVAR
EVAR-- 50cc
„ Will
using 50 mls instead of 100mls
limit CIN?
„ Need
large
g number of patients
p
„ Standardize hydration and premedication
„ Establish creatinine clearance 24, 48, 72
hours post
What we do not know?
„ Will
using 50 mls instead of 100mls
limit endoleak detection?
Delayed Scan
Stanford Radiology 10th Annual Multidetector
CT Symposium
4
Constantino S. Pena, MD: Low contrast volume
abdominal CTA
Plenty for Future Study
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54 year old female with HTN
Lower voltage scanning
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May 15, 2008- 3:20 PM
Increases contrast effect
May increase noise
S
Spectral
l CT scan
Dual Energy Scanning
Possibility of minimizing both contrast media
use and radiation dose
54 year old female with HTN
Conclusions
100 mls Chest to Ankle CTA
Thank You
• A 64-detector CTA protocols using low volumes of
CM provides uniform attenuation and excellent
visual depiction of the anatomical details in
aortoiliac imaging.
• A reduction in CM may offer improved imaging
options in AAA patients with borderline renal
function and renal insufficiency.
• Further research is warranted to assess the ability
of the low-volume CM protocol in depiction of
endoleaks and prevention of contrast nephropathy.
Stanford Radiology 10th Annual Multidetector
CT Symposium
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