1. Radiological imaging of lower limb ischemia.
Dr/ ABD ALLAH NAZEER. MD.

2. Acute limb ischemia is defined as “Any sudden decrease in limb perfusion
causing a potential threat to limb viability”. By convention this usually
refers to patients presenting with symptoms for less than 2 weeks. The
spectrum of acute limb ischemia therefore ranges from the patient with a
few hours history of a painful cold white leg, to the patient with a few days
history of short distance claudication or the patient with a sudden increase
in ischemic symptoms on a background of peripheral arterial disease.
Acute limb ischemia.
Pathophysiology
An embolus is defined as a material (gas, solid or liquid) that is carried
within the circulation and lodges in a blood vessel in another part of the
circulation, causing occlusion of the blood vessel. Radiologically the upper
border of an embolus is classically concave, known as the “meniscus” sign.
Acute : varies but up to 2 weeks
Chronic : > 2 weeks
Acute on Chronic : Sudden and rapid deterioration in symptoms

3. Common etiologies
1. Embolic – Causes 15% of ALI cases
• 80% from cardiac source - valve, mural thrombus
• 20% non-cardiac source - thrombosed aneurysm, ulcerated atherosclerotic plaque
• Decreasing incidence with fewer cases of rheumatic heart disease
• Most commonly lodged at: Femoral artery bifurcation, aortoiliac arterial system,
brachial artery
• Unique condition = Blue Toe Syndrome
-Sudden appearance of cool, painful foot with cyanosis/petechaie of toes and
plantar foot
- Paradoxically: normal pedal pulses
- Etiology: emboli to the digital arteries of the foot
- Management: Requires imaging for more proximal atherosclerotic lesion
- Should consider popliteal artery aneurysm
- Treatment: Antiocoagulation alone +/- surgical bypass of atherosclerotic lesion
2. Thrombotic – Causes 85% of ALI cases
• Of native or aneurysmal artery
• Most commonly located at: Bypass grant, common femoral artery, popliteal artery
• Of indwelling bypass graft

4. Less common etiologies
1. Extrinsic compression of arterial lumen
• Aortic or vascular dissection, creating pseudo lumen which compromises true lumen
• Compartment syndrome
• Thoracic outlet syndrome
2. Vasospasm
• Raynaud’s disease
- Vasospastic condition causing well-demarcated ischemia to fingers and toes
- Three stages: Pallor (hypoperfusion), then cyanotic (hypoxemia), then hyperemia
(reperfusion)
- Usually bilateral limb involvement
3. Vasculitis
• Buerger’s disease (Thromboangiitis obliterans)
- Segmental, inflammatory vaso-occlusive disease of small and medium arteries
-Heavy tobacco use is a significant risk factor
-• Temporal arteritis (Giant cell arteritis)
- Inflammatory condition of medium and large arteries
• Takayasu’s arteritis
- Chronic, inflammatory, large-vessel disease of aorta and its large branches
-Predominantly found in young women (age 20-30)
-4. Low intravascular volume +/- mild peripheral vascular disease (PVD)
• Congestive heart failure, dehydration, sepsis
5. Trauma

5. Imaging options
1. Digital subtraction angiography (DSA)
• Gold standard for limb ischemia imaging
• Advantages: During angiography, may be able to immediately start therapeutic
intervention (intra-arterial lysis) without losing time
• Disadvantages: 8% incidence of contrast nephrotoxicity .
- Relatively invasive
2. Duplex ultrasonography:
• Ultrasound with color flow and Doppler waveform information regarding vascular
flow and patency.
• Advantages: - Noninvasive and non-nephrotoxic
-Fairly accurate for infrainguinal arterial occlusive disease, especially of bypass grafts
in this location
• Disadvantages: - Time intensive (30-40 min)
- Suprainguinal arterial occlusions and distal run-off vessels not well-visualized
-Calcifications of arterial walls (in diabetic patients, especially) can create artifacts and
obscure visualization.
• Comparisons between duplex ultrasound versus angiography pre-operatively for
chronic limb ischemia showed a high correlation rate between the two.
• May be considered as a second-line approach to ALI imaging if angiography is not
possible for infrainguinal arterial occlusion.

6. 3. CT angiography (CTA)
• Advantages: - Noninvasive
-Can concurrently evaluate for aortic dissection while looking at runoff vessels
in the extremities.
-Promising literature regarding usefulness in staging severity of chronic
peripheral arterial disease (PAD):
Sensitivity of CTA = 96% and specificity = 97%
• Disadvantages: - Time intensive (30-40 min)
-Exposure to IV contrast –> If going to angiography after CTA for intra-arterial
lysis of clot, patient will now receive a 2nd contrast bolus, increasing the risk
of renal failure.
• Not well-studied in acute limb ischemia
4. MR angiography (MRA)
• Advantages: - Less contrast load than angiography
-Gadolinium IV contrast is safe for the kidneys
-No ionizing irradiation
• Disadvantages: - Very time intensive and often unavailable during weekend and
night hours.
-Promising literature regarding usefulness in staging severity of chronic PAD in
the femoral/popliteal system:

9. Thrombosis or embolism at femoral artery.
FA lumen is filled with hypoechoic thrombus or embolus . Normal flow in adjacent FV.

10. Occlusion of the CIA with reserved flow
in IIA (blue) to supply flow to EIA(red).

11. Short occlusion of the mid-SFA(large arrow) with
large collateral at both end of occlusion(small arrow).

13. Tardus et parvus = small amplitude + slow rising pulse

16. Color Doppler imaging: thrombosis
of the left common iliac artery.
Arteriography: severe stenosis
of the left common iliac artery.

17. Complete
occlusion of
the aorta and
proximal iliac
arteries

20. Angio-imaging of the popliteal trifurcation before
and after selective balloon embolectomy.

21. Thrombus of the left atrium with complete popliteal artery occlusion.

22. Angiogram showing bilateral occlusions of superficial femoral
arteries in thighs. Collaterals arising from the profunda
femoris artery can functionally bypass this occlusion.

23. Obstruction of the CFA with engorgement of the collateral vessels.

24. Acute thrombosis of the
femoropopliteal and trifurcation
vessels in an 84-year-old woman
with an acutely cool right leg. The
patient refused angiography. (a)
Transverse CT angiographic image
at the level of the adductor canal
shows rounded filling defect in the
right popliteal artery (arrow). The
contralateral left popliteal artery
(P) is patent at this level. (b) Large
field of view multipath CPR and (c)
enlarged image of popliteal region
show the extent of right-sided
thrombus (arrowheads). In
addition to the popliteal artery
(POP), the anterior tibial artery
(AT), tibioperoneal trunk (TPT),
and posterior tibial artery (PT) are
occluded. F, femoral condyle.
High-grade left popliteal
stenosis (asterisk) is also noted.

25. No flow at
the PT artery

26. Images of adventitial cystic
disease in a 55-year-old
patient. (a) Axial source
image from peripheral CT
angiography shows marked
compression of the popliteal
artery (P) by an ovoid fluid-
density lesion (arrowheads).
Note the predominant
transverse compression of the
flow lumen. F, fabella. (b)
Corresponding sagittal thin-
slab MIP image shows
craniocaudal extent of fluid-
density lesion in the popliteal
arterial wall (arrowheads). (c)
VR image viewed obliquely
from the posterior direction
demonstrates severe
narrowing of the right
popliteal artery (arrows).

27. CT Angiography. Digital Subtraction Angiography

28. CT angiography showing the presence of an intraluminal aortic
(short arrow) and iliac (long arrow) saddle embolus.

29. CT angiography of the lower limbs showing distal posterior and anterior tibial
artery occlusion of the left side and three-vessel occlusion of the right side.

30. Digital subtraction angiogram (DSA) illustrates a high-grade short-
segment stenosis of the lumen of the right superficial femoral artery (a).

31. (MRA) of the lower extremities was obtained by using the bolus-chase
technique. A short-segment high-grade stenosis is present in the middle
of the left superficial femoral artery. Note the collateral arterial supply.

32. Occlusion of the
left common
femoral artery.

33. Acute limb ischemia.

36. Acute right lower extremity pain and absent
popliteal and pedal pulses. There is an occlusion
of the popliteal artery caused by an embolus.
Acute limb ischemia with occlusion
of the SFA by embolus.

37. Occlusion of the popliteal artery
caused by an embolus.
Anterior tibial artery occluded
proximally with limited contrast filing of
ATA distally. The TPT and PTA are patent

39. Peripheral vascular disease, (chronic limb ischemia).

49. ABI Interpretation
1.00–1.29 Normal
0.91–0.99 Borderline
0.41–0.90 Mild-to-moderate
disease
≤0.40 Severe disease
≥1.30 Non compressible
Interpreting the Ankle-Brachial Index.

50. Segmental Pressures (mm Hg).

51. Pulse Volume Recordings

52. ABI in diabetics patient with calcification of
vessel wall and beaded appearance of color flow.

53. Severe stenosis of the SFA with area of color
flow disturbance and aliasing(Arrows).

54. Calcified atheroma of the SFA with drop-out
of color flow signal in parts of the lumen.

55. This elderly male diabetic patient had severe pain in the right leg. Colour Doppler ultrasound and
spectral Doppler tracing reveal severe diffuse stenotic disease of the arterial system starting from the
right popliteal artery to the dorsalis pedis artery. This kind of a picture is seen in long-standing
diabetes mellitus resulting in severe arterial disease or arteriopathy. The waveform of the arteries
affected including the popliteal artery, the anterior and posterior tibial arteries show loss of tri-phasic
spectral waveform which is replaced with spectral broadening and an almost venous like flow pattern.
This is known as severe dampening of the waveform and this also known as tardus parvus flow.

61. Peripheral CT angiogram of
a 62-year-old man with
abdominal and bilateral
common iliac artery
aneurysms and subacute
onset of right foot pain. (a)
Oblique (45° left anterior
oblique) MIP image of
entire data set. Box
indicates magnified views.
(b–d) axial CT images
through the right proximal
calf show embolic filling
defects in the anterior
tibial artery (arrowheads)
and the tibioperoneal trunk
(arrows). (e,f)
Corresponding CPR images
from the popliteal artery
through the anterior tibial
artery (e) and posterior
tibial artery (f) display
intraluminal filling defects.
DSA confirms CT
angiography findings (g).

62. Peripheral CT angiogram in an
83-year-old man with right
side–dominant calf and foot
claudication. Acceptable image
noise level in the abdomen and
unprecedented spatial
resolution down to the plantar
arch and metatarsal branches.
MIP of the entire data set (a);
VR views of the abdomen (b)
and right leg runoff (c–f) show
distal aortic calcific plaque and
patent renal arteries (b)
occlusion of the right popliteal
trifurcation with reconstitution
of the peroneal artery (c),
which reconstitutes the right
posterior tibial artery above
the ankle via a communicating
branch (d), and supplies the
foot through the common and
lateral plantar arteries (e)
which fill the plantar arch (f).

63. Peripheral CT angiography in a 72-
year-old woman with non healing left
forefoot ulcer. (a) VR image of the left
superficial femoral artery shows
excessive vessel wall calcifications,
precluding the assessment of the flow
channel. Cross-sectional views were
required to visualize the vessel lumen.
Axial CT images (b,c) through the
mid-superficial femoral artery (dotted
line in a and d) with viewing window
settings (level/width) of 200 HU/600
HU (b) does not allow us to
distinguish between opacified vessel
lumen and vessel calcification, which
can be distinguished only when an
adequately wide window width (300
HU/1,200 HU) is used (c). Similar wide
window settings are also used for a
CPR through the same vessel (d),
displaying several areas of wall
calcification with and without
stenosis.

64. Peripheral CT angiography (16
0.75 mm, 2.0 mm/1.0 mm) in a 73-
year-old woman with intermittent
claudication bilaterally. MIP (a)
shows long right femoropopliteal
occlusion (curved arrow) and
diffuse disease of the left
superficial femoral artery
with a short distal near-occlusion.
CPR (b) through left iliofemoral
arteries demonstrates multiple
mild stenosis of the external iliac
artery (arrowheads), a diffusely
diseased left superficial femoral
artery, and short (3 cm) distal left
superficial femoral artery
occlusion.
Corresponding selective DSA
images of the left external iliac
artery (c) and the distal left
superficial femoral artery (d) were
obtained immediately before
angioplasty/stent implantation.

65. Peripheral CT angiography (16 0.75
mm, 2.0 mm/1.0 mm) of a diabetic
male patient with bilateral
claudication. MIP (a) shows arterial
calcifications near the aortic bifurcation
(arrow), as well as in the right
(arrowheads) and left common femoral
arteries, in the right femoropopliteal
region, and in the crural vessels. A long
stent is seen in the left femoropopliteal
segment (curved arrow).Frontal view
(b) and magnified 45° left anterior
oblique (c) multipath CPR images
provide simultaneous CPRs through the
aorta and bilateral iliac through crural
arteries. Note that prominent
calcifications cause luminal narrowing
in the proximal left common iliac artery
(arrow) and in the right common
femoral artery (arrowheads). The left
common femoral artery is normal; the
long femoropopliteal stent is patent
(curved arrow). Mixed calcified and non
calcified occlusion of the right distal
femoral artery is also seen (open
arrow).

66. Intermittent left leg claudication in a 62-year-old
woman with a history of tobacco use and
aortobifemoral bypass grafting. The ankle-brachial
index was 0.65. (a– d) MIP images with bone
segmentation; (e– h) DSA images obtained before
treatment. (a) Oblique MIP image shows high-
grade stenosis (arrows) at the origin of the left
profunda femoris artery (P); a previously placed
aortobifemoral graft (G) is noted, as is a patent
superficial femoral artery (SFA). (b) Coronal MIP of
the left thigh demonstrates multifocal moderate to
severe stenosis in the SFA (arrowheads). The SFA is
small in caliber with soft and calcified plaque
present. (c) Coronal MIP of the calf shows a one-
vessel runoff (peroneal; PER) to the left foot. Mild
venous contamination (V) is present. (d) Sagittal
MIP image of the left foot shows collateral vessel
reconstitution (arrowheads) of the dorsalis pedis
(DP) above the ankle from the peroneal artery. (e)
DSA image from selective catheterization of the left
profunda femoris artery corroborates the CT
angiographic finding of high-grade profunda
femoris artery (P) stenosis (arrows). (f) DSA image
of left superficial femoral artery shows multiple
focal stenoses (arrowheads) in the same segment
of the superficial femoral artery as demonstrated
by CT angiography. Note the lack of calcium
visualization on the subtracted image from DSA. (g)
DSA image of the calf confirms single peroneal
vessel runoff. (h) DSA image of left foot confirms
reconstitution of the dorsalis pedis artery (DP) from
the peroneal artery (arrowheads).

67. Magnetic
Resonance
Angiography
(MRA) show
occlusion of
the left CIA
with filling
of the SFA
from
collateral.

68. (MRA) of the lower extremities was obtained by using the bolus-chase technique.
Atherosclerotic disease involves the bilateral superficial femoral arteries. Note the multiple
lesions, which are primarily in the middle portions, and the large collateral arterial supply.

69. 67-year-old man
with more than
10-year history of
diabetes mellitus
presented with
symptoms of limb
ischemia.

70. Thank You.