This document provides information about CT procedures for the lower limbs, including the hip, knee, and ankle joints. It describes patient preparation, positioning, scanning protocols, and reconstruction parameters for CT imaging of each area. Key anatomical structures are identified for the hip, knee, and ankle joints. Indications for lower limb CT include evaluation of tumors, fractures, infections, and joint abnormalities.

1. CT PROCEDURE
OF
LOWER LIMBAnjan Dangal
B.Sc.Medical Imaging Technology Student
National Academy of Medical Sciences
Bir Hospital, kathmandu, Nepal

2. Contents
• Indication
• Contraindication
• Anatomy of HIP Joint and Thigh + CT Procedure of Hip Joint

3. WHY Lower Extremity CT
Computed tomography (CT) is used for evaluation of tumors, metastatic
lesions, infection, fractures and other problems.
Magnetic resonance imaging (MRI) is the first-line choice for imaging of
many conditions, but CT may be used in these cases if MRI is
contraindicated or unable to be performed

4. • Evaluation of suspicious mass/ tumor (unconfirmed cancer
diagnosis
Initial evaluation of suspicious mass/tumor , which has been
nondiagnostic after x ray and ultrasound
Suspected tumor size increase or recurrence based on a sign,
symptom, imaging study or abnormal lab value

5. Evaluation of Known Cancer
Initial staging of known cancer in the lower extremity.
Follow-up of known cancer of patient undergoing active treatment within the past year.
Known cancer with suspected lower extremity metastasis based on a sign, symptom, imaging
study or abnormal lab value.Initial staging of known cancer in the lower extremity.
Follow-up of known cancer of patient undergoing active treatment within the past year.
Known cancer with suspected lower extremity metastasis based on a sign, symptom, imaging
study or abnormal lab value.

6. For evaluation of known or suspected fracture and/or injury:
Further evaluation of an abnormality or non-diagnostic findings on prior imaging.
Suspected fracture when imaging is negative or equivocal.
Determine position of known fracture fragments/dislocation.

7. For evaluation of persistent pain, initial imaging (e.g. x-ray) has been
performed and MRI is contraindicated or cannot be performed:
Chronic (lasting 3 months or greater) pain and/or persistent tendonitis
unresponsive to conservative treatment*, which include - medical
therapy (may include physical therapy or chiropractic treatments)

8. Pre-operative evaluation.
Post-operative/procedural evaluation:
When imaging, physical, or laboratory findings indicate joint infection,
delayed or non-healing, or other surgical/procedural complications.
A follow-up study may be needed to help evaluate a patient’s progress
after treatment, procedure, intervention, or surgery. Documentation
requires a medical reason that clearly indicates why additional imaging is
needed for the type and area(s) requested.

9. • For evaluation of known or suspected infection or inflammatory disease (e.g.
osteomyelitis)
• For evaluation of suspected (AVN) avascular necrosis (e.g., aseptic necrosis,
Legg-Calve-Perthes disease in children) and MRI is contraindicated or cannot be
performed
• For evaluation of suspected or known Auto Immune Disease, (e.g. Rheumatoid
arthritis)
• Abnormal bone scan and radiograph is non-diagnostic or requires further
evaluation.
• For evaluation of leg length discrepancy when physical deformities of the lower
extremities would prevent standard modalities such as x-rays or a Scanogram
from being performed.
• CT arthrogram and MRI is contraindicated or cannot be performed.
• To assess status of osteochondral abnormalities including osteochondral
fractures, osteochondritis dissecans, treated osteochondral defects where
physical or imaging findings suggest its presence and MRI is contraindicated or
cannot be performed.

10. Lower limb
Lower limb consists of :
Thigh
Leg
Ankle and Foot

11. HIP joint

12. Articulating Surface:
• Head of femur
• lunate surface of acetabulum:

13. Cup like cavity : Acetabulum
Ilium , Ischium and Pubis

14. Acetabular
fossaNon Articulating surface:
Loose connective tisssue,
mobile fat pad
not covered by hyaline
cartilage

15. ACETABULAR
LABRUM
Surrounds Bony rim of Acetabulum

16. Fovea
capitis femoris
ligament of head of femur connets
at fovea acetabular ligament

17. On Axial Section
Anterior column
Posterior Column

18. Ligaments
Outer ligaments
Inner ligaments

19. ILiofemoral ligament
Ischiofemoral ligament
pubofemoral ligament

22. ligament of head of femur
transverse Acetabular ligament

25. Head

26. Muscle of Hip and Thigh

27. Muscles of Hip and Thigh
• Anterior Hip Muscle
• Posterior Hip Muscle (Glueteal )
Superficial Gluteal Muscle
Deep Gluteal Muscle
• Anterior Compartment
• Medial compartment
• Posterior Compartment

28. Anterior Hip Muscles
Iliopsoas Muscle
Psoas Minor Muscle

29. Iliopsoas
Muscle
Psoas Muscle
Illiacus Muscle

30. Psoas
Minor
Muscle

31. • Posterior Hip Muscle (Glueteal )
Superficial Gluteal Muscle
Gluteus Maximus Muscle
Gluteal Medius Muscle
Gleteal Minimus Muscle
Tensor fasciae latae
Deep Gluteal Muscle

32. Superficial Gluteal Muscle
Gluteus Maximus Muscle
Gluteal Medius Muscle
Gleteal Minimus Muscle
Tensor fsciae latae

33. Gluteus Maximus Muscle

34. Gluteal
Medius
Muscle

35. Gluteus
Minimus
Muscle

36. Tensor
Fascia
Latae

37. Deep Gluteal Muscle
Piriformis muscle
Superior Gemellus Muscle
Obturator Internus Muscle
Inferior gemellus muscle
Quadratus femoris muscle

38. Piriformis
Muscle

39. Superior
Gemellus
Muscle

40. Obturator
Internus
Muscle

41. Inferior
Gemellus
Muscle

42. Quadratus
Femoris
Muscle

43. Muscles of Thigh
• Anterior Compartment
• Medial compartment
• Posterior Compartment

44. Muscle of thigh :
Ant Compartment
Sartorius Muscle
Quadriceps femoris Muscle

45. Sartorius
Muscle

46. Rectus
Femoris
Muscle

47. Blood Supply
major contributing set contains the medial and lateral
circumflex arteries that arise from the deep branch of
the femoral artery

48. Femoral
Artery

49. lateral
Circumflex
Femoral
Artery

50. Medial
Circumflex
Femoral
Artery

51. CT Procedure of Hip
Computed tomography is primarily used to evaluate acute trauma,
e.g., acetabular fracture or hip dislocation. It can detect
intraarticular fragments and associated articular surface fractures
and it is useful in surgical planning.

52. Additional Indications Specific to Hip CT
For any evaluation of patient with hip prosthesis or other implanted metallic
hardware where prosthetic loosening or dysfunction is suspected on physical
examination or imaging.
For evaluation of total hip arthroplasty patients with suspected loosening
and/or wear or osteolysis or assessment of bone stock is needed.
For evaluation of suspected slipped capital femoral epiphysis with non-
diagnostic or equivocal imaging and MRI is contraindicated or cannot be
performed.
Suspected labral tear of the hip with signs of clicking and pain with hip
motion especially with hip flexion, internal rotation and adduction which can
also be associated with locking and giving way sensations of the hip on
ambulation and MRI is contraindicated or cannot be performed.

53. Patient preperation
Remove any non-fixed metal prosthesis, jewelry or zippers that
might interfere with the region to be scanned.
- Discuss the procedure with the patient. The patient must not
move during any part of the scanning.
-

54. Patient Position
and Posture
• Patient laying supine with legs extended.
• Legs in natural alignment with neutral rotation.
• No un-natural tilt or lift of the pelvis.
• Arms folded upward away from the pelvis
• Position the patient to maximize comfort and minimize motion.
• Only true axial slices are allowed: no oblique or reformatted images and no gantry tilt

55. Hip Joint/ Proximal femurProtocol
Positioning patient supine, with feet first
Scouts AP and Lat
Scan Type Helical
Start Location Just Above SI Joint
End Location Approx 4cm below Lesser trochanter
DFOV ~ 30 cm ( Include Skin Surface )
Acqusition Detector Width * Number of detector in row= coverage
Reconstruction ( Slice Thickness/ Interval ) 1.25mm/ 0.625 mm
Pitch 0.5
Kvp 120
mA 200

56. Clinical indications that may necessitate IV contrast include infection
or tumor. When IV contrast is ordered, 80 mL of LOCM
is injected at 3 mL/s and scanning begins after 40 seconds.
Algorithm Bone
Window Width 2000
Window level 500
Algorithm Standard
Window width 350
Window level 50

57. A. Axial MPR can be programmed from an AP scout. B. Coronal MPR can be
programmed from an axial image and should follow the long axis of the femoral neck.
C. Sagittal MPR can be programmed from an axial image and should be perpendicular to the
coronal MPR plane.

58. MPR

59. 1. Acetabulum (anterior column)
2. Acetabulum
3.Femoral head
4. Acetabulum posterior column
5. Hip Joint
6. Illiopsoas mUscle
7. Sarotrius M
8.Gluteus Minimus M
9. Gletues Medius M
10. Gluteal Maximus Muscle
11. Bladder
12. Rectus Femoris

60. 1. Femoral head
2. Iliopsoas m.
3. Femoral neck
4. Rectus femoris m.
5. Tensor fascia lata m.
6. Greater trochanter
7. Ischium/Ischial tuberosity
8. Obturator internus m.
9. Pubis
10. Pectineus m.
11. Gluteus maximus m.
12. Sartorius m.

61. Adductor brevis m.
2. Rectus femoris m.
3. Vastus intermedius m.
4. Femur
5. Pubis, inferior ramus
6. Obturator externus m.
7. Iliopsoas m.
8. Femur, lesser trochanter
9. Gluteus maximus m.
10. Sartorius m.
11. Tensor fascia lata m.
12. Vastus lateralis m

62. VRT MPR : Coronal and
Sag Images

63. Knee Joint

64. Articulating Surface : Femur: lateral and medial condyles,
intercondylar groove, patellar surface
Tibia: tibial plateaus
Patella: posterior surface

65. Meniscus:Ameniscus(me-NIS-kus;a crescent;plural,menisci) isa pad
offibrocartilage betweenopposing boneswithinasynovial joint.
Meniscus:A meniscus (me-NIS-kus; a crescent; plural,
menisci) is a pad offibrocartilage between opposing
bones within a synovial joint.

66. Medial
Meniscus

67. Lateral
Meniscus

68. The transverse
ligament
connects
the menisci
anteriorly and
holds them in
place during knee
extension.

69. The anterior and
posterior
meniscofemoral
ligaments attach the
menisci to the femur
and the bases of the
menisci are attached
to the joint capsule.

70. Bursa: bursa is a small, thin, fluid-filled pocket that forms in
connective tissue outside of a joint capsule. It contains synovial
fluid and is lined by a synovial membrane.Bursae often form
where a tendon or ligament rubs against other tissues.
Suprapatellar
Infrapatellar
prepatellar

71. Suprapatellar

72. Infrapatellar

73. Prepatellar

74. Ligaments
Frontal ligamnets
Medial/lateral ligaments
dorsal
Cruciate ligament

75. Frontal ligament: The frontal ligamentous apparatus
holds the patella in place.
Patellar ligament
Retinaculum

76. Patellar
ligament

78. Lateral
patellar
Retinaculum

79. Medial
Patellar
Retinaculum

80. Medial/Lateral
ligament:The lateral and medial
ligaments secure thekneejoint,
preventexcessive sideways
movement.

82. Cruciate ligament:two cruciate ligaments cross in the
centre of the joint, preventing slippage of the femur on
the tibia

83. ACL

84. PCL

85. Flexors & Extensors of Knee

86. CT PROTOCOL OF KNEE

87. Additional indications specific for KNEE CT and MRI is
contraindicated or cannot be performed:
Accompanied by blood in the joint (hemarthrosis) demonstrated by aspiration.
Presence of a joint effusion.
Accompanied by physical findings of a meniscal injury determined by physical
examination tests (McMurray’s, Apley’s) or significant laxity on varus or valgus stress
tests.
Accompanied by physical findings of anterior cruciate ligament (ACL) or posterior
cruciate ligament (PCL) ligamental injury determined by the drawer test or the
Lachman test.

88. Patient preperation
Remove any non-fixed metal prosthesis, jewelry or zippers that
might interfere with the region to be scanned.
- Discuss the procedure with the patient. The patient must not
move during any part of the scanning.
-

89. Patient Position
and Posture
• Patient laying supine with legs extended.
• Legs in natural alignment with neutral rotation.
• No un-natural tilt or lift of the pelvis.
• Arms folded upward away from the pelvis
• Position the patient to maximize comfort and minimize motion.
• Only true axial slices are allowed: no oblique or reformatted images and no gantry tilt

90. KNEE/ TIBIAL PLATEAU
Positioning Patient Supine with feet first , Legs Flat on table
Scouts Ap and Lateral
Scan Type Helical
Start Location Just Above Patella
End Location Just below fibular Head
DFOV ~ 20cm ( adjust to include Skin Surface : affected knee only )
SFOV large Body
Acquisition Detector Width * Number of detector in row= coverage
Reconstruction ( Slice thickness/ interval ) 1.25mm/0.625 mm
Pitch 0.5
Kvp/ mA 120

91. Reconstruction 1
Algorithm Bone Plus
Window Width 2000
Window level 500
Reconstruction 2
Algorithm Standard
Window Width 350
Window level 50

92. MPR: Bone AlgorithmSlice Thickness/ Interval : 2mm/2mm
Planes: Axial, coronal, sagittal
A. Axial MPR can be programmed from an AP scout and should be parallel to the tibial plateau.
B. Coronal MPR can be programmed from an axial image and should be parallel to the femoral condyles.
C. Sagittal MPR can be programmed from an axial image and should be perpendicular to the coronal
MPR.

94. ANKLE JOINT

95. Articulation
Tibiotarsal joint: fibula, tibia, talus
Talotarsal joint: talus, calcaneus, navicular bone

96. LigamentsAnterior talofibular,
posterior talofibular,
Anterior Tibiofibular ligament
Posterior Tibiofibular ligament
calcaneofibular ligamnent
Anterior Tibiotalar ligamnet
Posterior Tibiotalar ligament
Tibionavicular ligamnet
Tibiotalar ligament

101. CT Protocol of Ankle/ Foot

103. Ankle/ Distal Tibia
Positioning Patient Supine with feet first , Legs Flat on table, use foot
holder
Scouts Ap and Lateral
Scan Type Helical
Start Location Just Above ankle joint
End Location Through calcaneus
DFOV ~ 16 cm ( adjust to include Skin Surface )
SFOV large Body
Acquisition Detector Width * Number of detector in row= coverage
Reconstruction ( Slice thickness/ interval ) 0.625mm/0.3 mm
Pitch 0.562
Kvp/ mA 120

104. Reconstruction 1
Algorithm Bone Plus
Window Width 2000
Window level 500
Reconstruction 2
Algorithm Standard
Window Width 350
Window level 50

105. MPR: Bone Algorithm
A. Axial MPR can be programmed from an AP scout parallel to the top of the talus.
B. Coronal MPR can be programmed from an axial image at the level of the distal tibia.
C. Sagittal MPR can be programmed from an axial image at the level of the distal tibia. They are perpendicular to the coronal MPR
plane.
Slice Thickness/ Interval : 2mm/2mm
Planes: Axial, coronal, sagittal

106. Thankyou