Transcript Vascular Analysis of Disease

Vascular Analysis of
Disease
In Nuclear Medicine
Blood Flow to the Extremities
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Consider chronic or acute disease
Blood flow interruption from arterial occlusions
Embolism, thrombus, or a vascular injury
Most procedures analyze venous blood flow and
physiological uptake of the radiotracer
However, given certain situations arterial
evaluation should be considered
Clinically Speaking
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Regional distribution of vascular flow can be done
using stress and rest procedures – Sound familiar?
Graft patency via blood flow determine viability
Evaluation of: ischemic ulcers and pre-amputation
AV malformation, shunts, vascular tumors,
embolization
Venous evaluation of infection and DVTs
Angiography issue is its failure to evaluate collateral
circulation
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Is there collateral circulation that contrast files to image
Post injection contrast does not evaluate physiology
Xenon Utilization
Purpose – To evaluate blood flow in muscle tissue
 Think of 133Xe and its imaging characteristics
 0.1 mL saline with 100 μCi 133Xe injected IM 1 to 2 cm
into muscle
 Needle is not removed for 30 seconds, but images or
data is collected in a serial mode
 Declining activity is quantified with semilog paper
 Procedure is done twice: stress and rest
Lower extremities
 Normal - 2 (rest) and 50 (stress) mL/min/100g
 Abnormal - <20 (stress) mL/min/100g
Arterial Evaluation
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Siegel el al. injected 99mTcHAM into the
descending aorta or femoral artery
Rest and stress images taken in the extremities
Compared with contrast angiography
Disease was confirmed in both: large vessel
occlusion, small vessel disease, ischemic ulcers,
and other
Test is rarely done with arterial injection because
of its invasive nature
Diffusible Tracer
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While a patient underwent 201Tl in cardiology whole
body scans were performed to evaluate muscle
distribution of the tracer
Segall et al. noted stress and redistribution images in the
legs with peripheral vascular disease
Normal patients: Leg activity = 25% of the total dose
with stress having a greater amount than rest
Abnormal – Rest imaging in the leg had higher levels of
activity when compared with stress indicating disease
Types of Vascular Evaluation
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Determining the level or area of amputation
based on ischemic areas in an extremity
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mL/min/100g evaluated at three points using 133Xe:
above the knee, below the knee, and the foot
Evaluate the pedicle flaps in reconstructive
surgery
mL/min/100g used with 133Xe and 99mTcO4 If a probe recorded delayed clearance, graft was not
viable
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Determine treatment of skin ulcers
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Similar - mL/min/100g analysis used
Frost Bite and Electrical Burns
Frost Bite
 99mTcO4- used to evaluate viable from non-viable tissue
in the finger and toes. Lack of activity indicated loss of
blood flow
Electrical Burns
 Using 99mTcPYP extent of muscle damage can be
determined
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Lacking uptake and flow was an indication of necrotic tissue
Delayed images also showed a donut shapes (cold center) and
focal hotspots indicating damaged viable to the tissue
Monitoring Therapeutic Embolization
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Polyvinyl alcohol spongelike (Ivalon) particles are used to
occlude AV malformation and vascular tumors
Particles are tagged with 99mTcsulfur colloid so that the
procedure can be monitored for its effectiveness
Catheter inserted and placed at the site of interest where
embolization occurs
If too Ivalon particles appear in the lung “PE” type issues occur,
requiring catheter adjustment
Repair of an Aneurysm
 99mTcRBCs
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are injected IV
to identify an aneurysm.
Green arrows indicate
aneurysm
Purple indicate repair
Note the difference in
radiopharmaceutical
distribution
Diagnosis of DVTs
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Contrast venography (gold standard) – 100
mL contrast injected into the dorsal vein in the
foot
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DVT is diagnosed when flow abruptly stops or lack
of deep vein filling occurs
Impedance Plethysmography (IPG) – Using
an inflated thigh cuff, blood flow impedance is
measure
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Releasing cuff pressure and the lack reduced venous
pressure via its electrical impedance is an indication
of DTV
Diagnosing DVT (cont.)
Ultrasound
 Color Doppler with
compression technique is
used to detect DVT
 Color separates venous
(blue) from arterial (red)
 Compression without the
vein compressing
indicates DVT
DVT/NMT Procedure
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Most common radiopharmaceutical is
99mTcMAA where bilateral IV is setup, one for
each foot
1 – 2 mCi are injected at the same time with
serial imaging
Alternative approach – tourniquet is applied at
different points on the leg and a set of injections
with serial images are taken
Detector placement must done at different
intervals
Tib/fib, knees, and thigh
 Depends on the size of the detector
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Biodistribution of the Particles
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Electrostatic forces
between MAA and DVT
cause the particles to
stick to the DVT
Perfusion lung can now
follow this procedure
What happens when you
flush your syringe when
injecting for a perfusion
lung scan?
AcuTect: General Information
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Used to diagnosis DVT
A synthetic peptide (not a MoAb!) - Apcitide
Binds to glycoprotein GP IIb/IIIa
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platelet receive signals that cause activation and
aggregation of the thrombus
Aggregation depended on GP IIb/IIIa receptor
AcutTect binds adhesion-molecule receptors found in the
accute DVT
Was quickly approved by the FDA
Produced by Diatide, Incorporated and distributed
by Nycomed Amersham
AcuTect: Clinical Trails (General)
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Two clinical trials where completed on patients
suspected of having DVT
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Study A = 136 patients
Study B = 145 patients
All patients where analyzed with AcutTect and
Contrast Venography
Total of 236 patients where finally processed
AcuTect: Clinical Trails - NMT Results
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Independently evaluated by NM physicians
Data collected at 10, 60,.120, 180 minutes
Asymmetry on early and delays defined a DVT
AcuTect: Clinical Trails Contrast
Venography
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Two groups of radiologies evaluated the data
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Group 1: Three independent radiologists from the imaging
centers
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Blinded to all other clinical data
No established reading criteria defined
Group 2: Three radiologists at one research center
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Blinded to all other clinical data
Established criteria
AcuTect: Clinical Trails Results
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AcuTect Results
 Study A = 54 (48%)
 Study B = 41 (33%)
Contrast Venography Results from Group 1
 Study A = 51 (45%)
 Study B = 101 (82%)
Contrast Venography Results from Group 2
 Study A = 24 (21%)
 Study B = 40 (33%)
AcuTect vs Group 2 (Research Center) Agreement rate
 Study A = 56-71%
 Study B = 66-73%
AcuTect: Comments/
Recommendations
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Literature research seems limited
Can it be done before or after a V/Q lung scan?
Protocol suggest 10 and 60 minute delayed images
Digital image for contrast enhancement
Small peptides may be immunogenic
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642 observed for 3 hours
1 patient became hypotensive from 10 to 60 minutes post
dose
AcuTech: Normal variants
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Collateral and superficial veins
Postsurgical sites
Nonvascular locations: joints, prostheses, muscle, skin,
and soft tissue
Key - If the uptake does not persist in the late images
then its normal
AcuTech Case Study
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29 year old male
hospitalized with extensive
burns presented with a 2
day history of left calf and
knee pain. The suspected
area was warm to the
touch.
Increased persistent uptake
is noted in the distal
femoral, popliteal, and
posterior calf vein.
Confirmed with contrast
venography