lFtl Three-Dimensional Fetal by mpe18147

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									    18th Annual Ob/Gyn Ultrasound Update for Clinical Practice.
              Fort Lauderdale Florid December 2009




 Three-Dimensional F t l
 Th    Di     i   l Fetal
           Easy,
Neuroscan: Easy Fast and
       Diagnostic
      E. Timor Tritsch,
 Ilan E Timor-Tritsch Ana Monteagudo Eran
                   Bornstein
    New York University School of Medicine
               Disclaimer

• I have no relevant financial relationships or
  conflict of interests involving the subject
  matter of this lecture
                        Objectives
• Advantages of 3D neurosonography
• Acquisition techniques
• 3D Orientation: navigate within the volume using the
  multiplanar mode to obtain diagnostic planes

• Display modalities
   – Tomographic ultrasound imaging mode (TUI)
   – Thick slice mode
   – Static volume contrast imaging (VCITM)
   – Inversion mode
   – 3D angiography (brain vasculature)
• Emphasis through examples of both normal and
  pathologic cases
                     3D Ultrasound
• Advancements in 3D ultrasound enable the acquisition of
  spatial ultrasound data which are saved as a voxel-
  based volume.
 Voxel: the smallest 3D-US picture unit




• Data can be analyzed and displayed in multiple directions/
  planes,
  planes and various display modes that exceed the
  capacities of 2D ultrasound
Advantages of 3D in Neurosonography

                                             g
• Simultaneous evaluation of the three ortogonal p  planes
• Reconstruct planes that are difficult to obtain by 2D US
  (fetal position / Probe limitations)

                                             3 perpendicular planes
•   Using the "marker / reference dot”:
    (generated by the intersection of the
    three ortogonal planes marking the
    same voxel within the volume). This
    enables us to pinpoint the structure
    of interest in one plane and having it
    displayed simultaneously in the
    other 2 planes
Advantages of 3D in Neurosonography

               Off line
 • Bed side / Off-line analysis
 • Off-site (expert consultation)
 • Data is easily revisited (allows additional
   evaluation)
 • Short processing time
 • Effective teaching tool (simulating real time
   sca
   scanning)g)
            Volume Acquisition
•    Acquisition of good quality is the basis of any
     3D analysis
•    Acquisition should attempt to overcome some
        q                      p
     of the inherent limitations of 3D sonography:
    1. Acoustic shadowing: shadow on the acquisition
       plane will be embedded in the volume
    2. Fetal movement: motion artifacts
    3. Fluid-tissue
    3 Fluid tissue interface if surface rendering is desired
    4. Fetal position, maternal obesity may challenge 3D
       assessment just as in 2D US
       Finding the Right Acoustic Window

 Anterolateral
 Fontanel
 Squamosal                         Parietal
                      Frontal      bone
 Suture
 Suture.              bone


 Posterolateral
 Fontanel
 Lambdoidal
 L bd id l
 Suture




          Occipital
          bone




                                             Sagittal suture   Metopic suture
Courtesy: Dr. Monteagudo        Anterior fontanelle (bregma)
            Transvaginal Acquisition
 • Our preferred mode: Excellent resolution (high frequency
   probe through the fontanelle / sutures
 • Fetal position: Gentle manipulation of the fetus by the
   examiners’ free hand to perfectly align the footprint of the
   probe with a fontanelle / suture
 • Version in selected cases

                              plane.
• Acquisition in the sagittal plane
• Acquisition in the coronal plane
                         90
  by rotating the probe 90°
• Acquisition angle (sweep): 60°-80°
  (fetal brain occupies the entire
  volume)
       Trans-abdominal Acquisition
• Attempt to acquire through an acoustic window
• Use two perpendicular planes
• Sagittal acquisition (metopic suture): excellent quality,
  may be hard to obtain
• Axial acquisition: easy to perform, attempt through the
  squamosal suture


Acquisition angle (sweep): 45° (2nd
trimester), 60° (3rd trimester)
Movement Artifacts
   Minimizing Movement Artifacts

• Increased acquisition speed (tradeoff between
  resolution and movement artifacts)
• Acquire in a time period with no fetal movements
• Instruct patients to hold their breath and not
  move during the acquisition (Doppler volumes
           q         g     q
  which require longer acquisition time) )
    Orientation Within The Volume:
                           Marker Dot
Multiplanar Mode and the “Marker Dot”
       Orientation in the Volume




1.   The marker dot in box b was placed in the cavum septi pelucidi
2.   90˚ Z rotation of the axial image in box C so that the front of the
     fetal head faces downwards
3.   “Fine-tune” into the perfect orientation
4.   Perfect alignment in all planes
  Scrutinizing the Brain to Complete
          Detailed Neuroscan
        a D il d N


  After    f t i t ti i bt i d               ti i th
• Aft perfect orientation is obtained we scrutinize the
  brain by performing a complete “sweep” in each one
  of the 3 ortogonal planes

• Includes all of the planes that are recommended by
  ISUOG guidelines for dedicated neurosonography
    ISUOG guidelines for Basic Brain
             Evaluation
             E l i
a          Axial planes




           b


c
    ISUOG guidelines for Dedicated
         Neurosonography
         N               h
          p                        g     p
• Coronal planes: 4 successive • Sagital planes: Median
                                 and 2 paramedian
The Coronal sweep
Sagittal Evaluation




        ah


                       ph




                  ih
 The Tomographic Ultrasound Imaging
              Mode
• Display successive “sliced” sections (similar to CT and MRI)
• Extremely useful: simulating a sweep on the selected plane
• The operator controls the number and thickness of slices
Side to side: Sagittal sweep




                               Top to bottom: axial sweep
               Thick Slice Mode
  May be      d to h         d detection: Th software
• M b used t enhance edge d t ti           The ft
  “collapses” a pre-selected number of successive slices
          p y                      g
  and displays it as a rendered image
Static Volume Contrast Imaging (VCITM)
 • Noise and speckle reduction, increased contrast
   resolution by displaying a thin slice
 • We routinely use a slice thickness of 1-3 mm




                      VCITM
                   Inversion Mode
 • Inverts anechoic structures into a cast-like
   appearance (as in the negative of a film)
 • Useful in imaging fluid filled structures such as the
   ventricular system
                y




Day WR. Brain 1959:82:109-115
Ventriculomegaly
Hydrocephaly
       Coronal
                                           Median


                              Diencephalon
                                – future 3rd
                                 ventricle
           R



                                                                                           Ant


                                                                            Rhombencephalon
                                                                            – future 4th ventricle

                              Interhemispheric
                              foramina (Monro)

                                                               D
       T       T

 Ant



  Horizontal                           Telencephalon – future lateral ventricles & hemispheres
Courtesy: Dr. Timor-Tritsch
Median                                 Coronal




                                   Rhombencephalon




               Di     h l
               Diencephalon




             Fused anterior horn

Horizontal
                           Anterior view
                    3D Angiography
•   Power/ Color Doppler (brain vasculature)
•   Pericallosal branch of the anterior cerebral artery
•   may assist us to trace a deviant artery (due to a mass effect)
Evaluation of Brain Vasculature
Mutiplanar Mode: AGCC
Mutiplanar Mode: AGCC
Mutiplanar Mode: AGCC
TUI Mode: AGCC
TUI Mode: AGCC
           Power Doppler: AGCC




                                  Normal pericallosal artery



Interrupted pericallosal artery
TUI: (Semilobar Holoprosencephaly)
Inversion: (Semilobar Holoprosencephaly)
TUI/ Power Doppler: Meningocele

                     Scull defect



                    Blood vessel traversing
                    the scull defect
         The Posterior Fossa
Reconstruction of the median plane allows for a
   detailed evaluation of the posterior fossa:
 the vermis and its relation to the brain stem
                          Summary
  3D ultrasound can and should be incorporated as a
  complementary mode to evaluate the fetal brain
               y

• Reconstruction of planes which may be difficult to obtain by 2D
• Simultaneous evaluation of the three orthogonal planes
• Multiple display modalities facilitating the diagnostic process
• Off line analysis/ Post processing/ Off site expert consultation
        p        g
• Short processing time
• Excellent teaching tool
                      g
Thank You For Listening
 Eran Bornstein, MD, Ilan E. Timor-Tritsch, MD
    New York University School of Medicine

								
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