Sacroiliac joint (PA sacrum view)
Updates to Article Attributes
Title
was changed:
Sacroiliac jointsjoint: PA Sacrumsacrum view
Status
changed from pending review to published (public).
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.
Body
was changed:
The PA Sacrum projection is a useful part of the sacroiliac series. Due to the shallow obliquity of the SIJ, the prone position allows the diverging x-ray beam to project through the joint space giving better visualisation of the joint compared to the AP projection1
Patient position
· Patient
-
patient is prone on the imaging table with legs extended
·Patient - patient’s shoulders and ASISs are at equal distances from the imaging table
Technical factors
·
-
PAposterioranterior projection· -
centring point
oCR-
central ray midline at a level 1
.5cm.5 cm below crest (at level ofPSISposterior superior iliac spine)oCR -
central ray with a caudal angle of 30°- 35°
·
-
central ray midline at a level 1
-
collimation
o- laterally to include both sacroiliac joints
o - superiorly and inferiorly to include the entire sacrum
·
- laterally to include both sacroiliac joints
-
orientation
-
portrait
oportrait·
-
portrait
-
detector size
o- 18 cm x 24 cm
·
- 18 cm x 24 cm
-
exposure
o- 75 kVp
o - 20-30 mAs
·
- 75 kVp
-
SID
o- 100 cm
·
- 100 cm
-
grid
o- yes
Image technical evaluation
· The
-
the sacroiliac joints are demonstrated open without foreshortening
·The -
the sacrum should be free of foreshortening and the inferior segments of the sacrum should be overlapped over the symphysis pubis2
·The -
the mid
sagittal-sagittal plane of the sacrum should be aligned with the symphysis pubis to ensure no rotation
Practical points
· When
-
when possible, imaging the sacroiliac joints in a posterior
anterior-anterior position is preferred in terms of demonstration the sacroiliac joints and dose3·The -
the sacroiliac joint runs in an oblique coronal orientation, PA imaging allows the diverging x-ray beam to project through the joint space, better visualising it compared to an AP projection
Due - due to tissue compression, the PA projection for SIJ imaging significantly lowers radiation dose compared to the AP projection without compromising image quality3
-<p>The <strong>PA Sacrum</strong> projection is a useful part of the sacroiliac series. Due to the shallow obliquity of the SIJ, the prone position allows the diverging x-ray beam to project through the joint space giving better visualisation of the joint compared to the AP projection<sup>1</sup></p><p><strong>Patient position</strong></p><p><!--[if !supportLists]-->· <!--[endif]-->Patient is prone on the imaging table with legs extended</p><p><!--[if !supportLists]-->· <!--[endif]-->Patient’s shoulders and ASISs are at equal distances from the imaging table</p><p><strong>Technical factors</strong></p><p><!--[if !supportLists]-->· <!--[endif]--><strong>PA projection</strong></p><p><!--[if !supportLists]-->· <!--[endif]--><strong>centring point</strong></p><p><!--[if !supportLists]-->o <!--[endif]-->CR midline at a level 1.5cm below crest (at level of PSIS)</p><p><!--[if !supportLists]-->o <!--[endif]-->CR with a caudal angle of 30 °- 35°</p><p><!--[if !supportLists]-->· <!--[endif]--><strong>collimation</strong></p><p><!--[if !supportLists]-->o <!--[endif]-->laterally to include both sacroiliac joints</p><p><!--[if !supportLists]-->o <!--[endif]-->superiorly and inferiorly to include the entire sacrum</p><p><!--[if !supportLists]-->· <!--[endif]--><strong>orientation </strong><em> </em></p><p><!--[if !supportLists]-->o <!--[endif]-->portrait</p><p><!--[if !supportLists]-->· <!--[endif]--><strong>detector size</strong></p><p><!--[if !supportLists]-->o <!--[endif]-->18 cm x 24 cm</p><p><!--[if !supportLists]-->· <!--[endif]--><strong>exposure</strong></p><p><!--[if !supportLists]-->o <!--[endif]-->75 kVp</p><p><!--[if !supportLists]-->o <!--[endif]-->20-30 mAs</p><p><!--[if !supportLists]-->· <!--[endif]--><strong>SID</strong></p><p><!--[if !supportLists]-->o <!--[endif]-->100 cm</p><p><!--[if !supportLists]-->· <!--[endif]--><strong>grid</strong></p><p><!--[if !supportLists]-->o <!--[endif]-->yes</p><h4>Image technical evaluation</h4><p><!--[if !supportLists]-->· <!--[endif]-->The sacroiliac joints are demonstrated open without foreshortening</p><p><!--[if !supportLists]-->· <!--[endif]-->The sacrum should be free of foreshortening and the inferior segments of the sacrum should be overlapped over the symphysis pubis<sup>2</sup></p><p><!--[if !supportLists]-->· <!--[endif]-->The mid sagittal plane of the sacrum should be aligned with the symphysis pubis to ensure no rotation</p><h4>Practical points</h4><p><!--[if !supportLists]-->· <!--[endif]-->When possible, imaging the sacroiliac joints in a posterior anterior position is preferred in terms of demonstration the sacroiliac joints and dose<sup>3</sup></p><p><!--[if !supportLists]-->· <!--[endif]-->The sacroiliac joint runs in an oblique coronal orientation, PA imaging allows the diverging x-ray beam to project through the joint space, better visualising it compared to an AP projection </p><p>Due to tissue compression, the PA projection for SIJ imaging significantly lowers radiation dose compared to the AP projection without compromising image quality<sup>3</sup></p>- +<p>The <strong>PA Sacrum</strong> projection is a useful part of the sacroiliac series. Due to the shallow obliquity of the SIJ, the prone position allows the diverging x-ray beam to project through the joint space giving better visualisation of the joint compared to the AP projection <sup>1</sup></p><h4>Patient position</h4><ul>
- +<li>patient is prone on the imaging table with legs extended</li>
- +<li>patient’s shoulders and ASISs are at equal distances from the imaging table</li>
- +</ul><h4>Technical factors</h4><ul>
- +<li><strong>posterioranterior projection</strong></li>
- +<li>
- +<strong>centring point</strong><ul>
- +<li>central ray midline at a level 1.5 cm below crest (at level of posterior superior iliac spine)</li>
- +<li>central ray with a caudal angle of 30°- 35°</li>
- +</ul>
- +</li>
- +<li>
- +<strong>collimation</strong><ul>
- +<li>laterally to include both sacroiliac joints</li>
- +<li>superiorly and inferiorly to include the entire sacrum</li>
- +</ul>
- +</li>
- +<li>
- +<strong>orientation </strong><ul><li>portrait<em> </em>
- +</li></ul>
- +</li>
- +<li>
- +<strong>detector size</strong><ul><li>18 cm x 24 cm</li></ul>
- +</li>
- +<li>
- +<strong>exposure</strong><ul>
- +<li>75 kVp</li>
- +<li>20-30 mAs</li>
- +</ul>
- +</li>
- +<li>
- +<strong>SID</strong><ul><li>100 cm</li></ul>
- +</li>
- +<li>
- +<strong>grid</strong><ul><li>yes</li></ul>
- +</li>
- +</ul><h4>Image technical evaluation</h4><ul>
- +<li>the sacroiliac joints are demonstrated open without foreshortening</li>
- +<li>the sacrum should be free of foreshortening and the inferior segments of the sacrum should be overlapped over the symphysis pubis <sup>2</sup>
- +</li>
- +<li>the mid-sagittal plane of the sacrum should be aligned with the symphysis pubis to ensure no rotation</li>
- +</ul><h4>Practical points</h4><ul>
- +<li>when possible, imaging the sacroiliac joints in a posterior-anterior position is preferred in terms of demonstration the sacroiliac joints and dose <sup>3</sup>
- +</li>
- +<li>the sacroiliac joint runs in an oblique coronal orientation, PA imaging allows the diverging x-ray beam to project through the joint space, better visualising it compared to an AP projection</li>
- +<li>due to tissue compression, the PA projection for SIJ imaging significantly lowers radiation dose compared to the AP projection without compromising image quality <sup>3</sup>
- +</li>
- +</ul>
References changed:
- 1. Bruce W. Long, Jeannean Hall Rollins, Barbara J. Smith. Merrill's Atlas of Radiographic Positioning and Procedures. (2015) <a href="https://books.google.co.uk/books?vid=ISBN9780323263412">ISBN: 9780323263412</a><span class="ref_v4"></span>
- 2. Kathy McQuillen Martensen. Workbook for Radiographic Image Analysis. (2019) <a href="https://books.google.co.uk/books?vid=ISBN9780323544634">ISBN: 9780323544634</a><span class="ref_v4"></span>
- 3. Mekiš N, Mc Entee M, Stegnar P. PA Positioning Significantly Reduces Testicular Dose During Sacroiliac Joint Radiography. Radiography. 2010;16(4):333-8. <a href="https://doi.org/10.1016/j.radi.2010.04.003">doi:10.1016/j.radi.2010.04.003</a>
- 1. Frank E, Long B, Smith B, Merrill V. Merrill's atlas of radiographic positioning & procedures. 12th ed. Jeanne Olson;. 2. McQuillen-Martensen KMcQuillen-Martensen K. Radiographic image analysis workbook. 2nd ed. St. Louis, Mo.: Elsevier Saunders; 2006. 3. Mekiš N, Mc Entee M, Stegnar P. PA positioning significantly reduces testicular dose during sacroiliac joint radiography [Internet]. http://www.radiographyonline.com/. 2016 [cited 12 December 2016]. Available from: http://www.radiographyonline.com/article/S1078-8174(10)00047-7/fulltext
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