Where should the arms be placed for a lateral projection of the thoracic spine?

Citation, DOI & article data

Citation:

Murphy A, Saber M, Er A, et al. Cervical spine (swimmer's lateral view). Reference article, Radiopaedia.org (Accessed on 14 Dec 2022) https://doi.org/10.53347/rID-48437

Cervical spine swimmer's lateral view is a modified lateral projection of the cervical spine to visualize the C7/T1 junction. 

As technology advances, computed tomography has replaced this projection, yet there remain many institutions (especially in rural areas) where computed tomography is not readily available.

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This view is most often performed when a standard lateral view cannot image the cervicothoracic junction due to patients having a dense, muscular shoulder. It can help to visualize subluxation and fractures involving the inferior cervical spine, superior thoracic spine and adjacent soft tissue.

• the patient is supine or erect, depending on trauma or follow up  
• the detector is placed running parallel to the long axis of the cervical spine
• the arm closest to the detector is placed above the patient's head, resting on the head for support
• the opposite arm is placed by the patient's side, as posterior to the patient as possible (maintaining spinal precautions if they are in place)
• image is taken on suspended expiration

• lateral projection
• centering point
  • 2.5 cm above the jugular notch at the level of T1
• collimation
  • superior to C1
  • inferior to T3
  • anterior to the extent of the vertebral bodies
  • posterior to the spinous process
• orientation  
  • landscape
• detector size
  • 24 cm x 30 cm
• exposure
  • 80-90 kVp
  • 120-150 mAs
• SID
  • 100 cm
• grid
  • yes

• there should be a clear visualization of C7 to T1
• the vertebral bodies are superimposed laterally
• the articular pillars and zygapophyseal joints are superimposed

The concept of this projection is to clear the superimposing humeral heads of the cervical spine, the offset of the arms attempts to achieve this. This projection is technically demanding and very hard to replicate consistently.

The technique will vary from radiographer to radiographer; however, they will all have their pitfalls.

This projection is regularly high stakes in resuscitation rooms and is utilized to assess critical anatomy, for those who do not have the privilege to use a superior modality such as CT 1.

Here are some handy hints:

• collimate incredibly tight, because this is such a high dose projection the scatter will be at an all-time high; collimation will alleviate this
• take your time setting the patient up, rushing this projection will only cause you headaches down the road
• use two filters, one filter anterior and one superior; this will even out the density
• if the patient is not on spinal precautions i.e. follow-up examination for metal work, rotate the patient 10 degrees RAO to offset the humeral heads

References

Related articles: Imaging in practice

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Citation, DOI & article data

Citation:

McWilliam R, Murphy A, Bell D, et al. Thoracic spine (lateral view). Reference article, Radiopaedia.org (Accessed on 14 Dec 2022) https://doi.org/10.53347/rID-49255

The thoracic spine lateral view images the thoracic spine, which consists of twelve vertebrae.

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This projection is utilized in many imaging contexts including trauma, postoperatively, and for chronic conditions. It can help to visualize any compression fractures, subluxation or kyphosis, and is used in conjunction with the AP view to complete a thoracic spine series. 

• the patient is erect, supine or lateral decubitus depending on clinical history
  • ideally, spinal imaging should be taken erect in the setting of non-trauma to give a functional overview of the thoracic spine
  • all imaging of patients with a suspected spinal injury must occur in the supine position without moving the patient
  • the lateral projection requires the upper limbs to be removed from the path of the direct x-ray beam, minimizing the superimposition of the proximal humeri over the thoracic vertebrae
  • in all variations of positioning, the humeri are extended 90º to the thorax, with the elbows flexed so that the forearms are parallel to the thorax

• lateral projection
• suspended expiration (or breathing technique if possible) 
• centering point
  • the level of the 7th thoracic vertebra, which correlates to the inferior border of the scapula, centered directly over the thoracic spine (most commonly equates to the posterior third of the thorax) 
  • the central ray is perpendicular to the image receptor 
• collimation
  • superiorly to include the C7/T1 junction
  • inferiorly to include the T12/L1 junction
  • anterior and posterior to include the anterior margin of all thoracic vertebrae and posterior to include the posterior column elements. 
• orientation  
  • portrait
• detector size
  • 35 cm x 43 cm 
• exposure
  • 80-100  kVp
  • 40-80 mAs 
• SID
  • 110 cm
• grid
  • yes (ensure the correct grid is selected if using focused grids)

The entire thoracic spine should be visible from T1 to T12:

• intervertebral joints and neural foramen are open, with the superimposition of the posterior spinous processes and posterior rib articulation indicating a true lateral has been achieved
• adequate image penetration and image contrast is evident by clear visualization of thoracic vertebral bodies, with both trabecular and cortical bone demonstrated
• visualization of the upper thoracic spine is often difficult given the patient thickness at this region. If clinical concern for injury in this area is strong, the cervical spine: swimmer's lateral view can be included, or referral to CT can be made

• the three-column concept of thoracolumbar spinal fractures is of particular importance when assessing this image for pathology
• exaggerated thoracic kyphosis can mean the field of view is wide and can include the majority of the anterior thorax; be aware of this when collimating and choosing the coronal centering point
• horizontal beam imaging can produce unwanted image artefact. Attempt to remove all potential artefacts including excessive sheets/blankets and monitoring devices (if safe)
• when moving the patient's arm be aware of any concurrent shoulder girdle injuries; if the patient is unable to extend the humeri 90º to the thorax, place an immobilization wedge over the thorax and ask them to extend their arms over this equipment; this will help to decrease superimposition whilst maintaining a level of patient comfort
• in order to achieve a true lateral projection, a caudal or cephalic tube angulation may be required, depending on spine curvature
• utilizing the handle commonly used for erect lateral chest radiographs can provide support for patients in this position, whilst simultaneously removing the humeri away from the upper thoracic region

References

Related articles: Imaging in practice

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