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USS techniques

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Spinal procedure

Cervical USS

Figure 1. Surface anatomy of the posterior neck region. After dividing the line from external occipital protuberance to mastoid process into 3 sections, greater occipital nerve usually runs the point at the junction of its middle and medial thirds (white arrow). Drawing the line one finger breadth laterally from midline, there are laminae on this line (black arrows). Two finger breadths laterally, facet joints are on this line (arrowheads). E, external occipital protuberance; C2, spinous process of the 2nd cervical vertebra; C7, spinous process of the 7th cervical vertebra.
Figure 1. Surface anatomy of the posterior neck region. After dividing the line from external occipital protuberance to mastoid process into 3 sections, greater occipital nerve usually runs the point at the junction of its middle and medial thirds (white arrow). Drawing the line one finger breadth laterally from midline, there are laminae on this line (black arrows). Two finger breadths laterally, facet joints are on this line (arrowheads). E, external occipital protuberance; C2, spinous process of the 2nd cervical vertebra; C7, spinous process of the 7th cervical vertebra.
Surface anatomy of the anterior neck region. Below the chin, hyoid bone (H) situated opposite the 3rd cervical vertebra can be easily palpated at midline. A finger's breadth below, there is the laryngeal prominence of the thyroid cartilage (T). The outlines of the thyroid cartilage are readily palpated. Below its lower, anterior part of the cricoid cartilage (C) forms an important landmark on the front of the neck because it lies opposite the 6th cervical vertebra. Arrow indicates sternocleidomastoid muscle.
Surface anatomy of the anterior neck region. Below the chin, hyoid bone (H) situated opposite the 3rd cervical vertebra can be easily palpated at midline. A finger's breadth below, there is the laryngeal prominence of the thyroid cartilage (T). The outlines of the thyroid cartilage are readily palpated. Below its lower, anterior part of the cricoid cartilage (C) forms an important landmark on the front of the neck because it lies opposite the 6th cervical vertebra. Arrow indicates sternocleidomastoid muscle.
 

Lumbar USS

Axis of scan: paramedian sagittal scan (A) at the level of the lamina; (B) at the level of the articular process; and (C) at the level of the transverse process.
Axis of scan: paramedian sagittal scan (A) at the level of the lamina; (B) at the level of the articular process; and (C) at the level of the transverse process.
(A) The water-based spine phantom. The lumbosacral spine is immersed in a water bath and imaged through the water using a curved linear transducer. The other images are sonograms from the water-based lumbosacral spine phantom showing (B) the transverse spinous process (SP) view; (C) the median sagittal spinous process view; and (D) the transverse interspinous view. An inset image has been placed next to figure (d) to illustrate the resemblance of the sonographic appearance of the transverse interspinous view to a cat’s head; hence, this is referred to as the “cat’s head sign.” AP, articular process; ISS, interspinous space; SC, spinal canal; SP, spinous process; SS, sagittal scan; TP, transverse process; TS, transverse scan; VB, vertebral body.
(A) The water-based spine phantom. The lumbosacral spine is immersed in a water bath and imaged through the water using a curved linear transducer. The other images are sonograms from the water-based lumbosacral spine phantom showing (B) the transverse spinous process (SP) view; (C) the median sagittal spinous process view; and (D) the transverse interspinous view. An inset image has been placed next to figure (d) to illustrate the resemblance of the sonographic appearance of the transverse interspinous view to a cat’s head; hence, this is referred to as the “cat’s head sign.” AP, articular process; ISS, interspinous space; SC, spinal canal; SP, spinous process; SS, sagittal scan; TP, transverse process; TS, transverse scan; VB, vertebral body.
 
Axis of scan: paramedian sagittal oblique scan of the lumbar spine. Note the medial direction of the US beam (blue). ESM, erector spinae muscle; IVC, inferior vena cava; PM, psoas major muscle; PMSOS, paramedian sagittal oblique scan; PMSS, paramedian sagittal scan (red); VB, vertebral body.
Axis of scan: paramedian sagittal oblique scan of the lumbar spine. Note the medial direction of the US beam (blue). ESM, erector spinae muscle; IVC, inferior vena cava; PM, psoas major muscle; PMSOS, paramedian sagittal oblique scan; PMSS, paramedian sagittal scan (red); VB, vertebral body.
 
Midline
Median sagittal sonogram of the lumbar spine showing the crescent-shaped hyperechoic reflections of the spinous processes. Note the narrow interspinous space in the midline. The inset image shows a corresponding computed tomography (CT) scan of the lumbosacral spine through the median plane. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive.
Median sagittal sonogram of the lumbar spine showing the crescent-shaped hyperechoic reflections of the spinous processes. Note the narrow interspinous space in the midline. The inset image shows a corresponding computed tomography (CT) scan of the lumbosacral spine through the median plane. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive.
 
Sagittal anatomy of the lumbosacral spine in the median plane.
Sagittal anatomy of the lumbosacral spine in the median plane.
Median sagittal sections of the lumbosacral spine. (A) Three-dimensional (3D) reconstruction of high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Median sagittal sonogram showing the spinous process (SP) and interspinous space (ISS). (C) Median sagittal cadaver anatomical section.
Median sagittal sections of the lumbosacral spine. (A) Three-dimensional (3D) reconstruction of high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Median sagittal sonogram showing the spinous process (SP) and interspinous space (ISS). (C) Median sagittal cadaver anatomical section.
Paramedian
Sagittal cadaver anatomical section of the lumbar spine through the lamina of the lumbar spine, rendered from the Visible Human Server male dataset. ESM, erector spinae muscle; ILS, interlaminar space; ITS, intrathecal space; IVD, intervertebral disc; VB, vertebral body.
Sagittal cadaver anatomical section of the lumbar spine through the lamina of the lumbar spine, rendered from the Visible Human Server male dataset. ESM, erector spinae muscle; ILS, interlaminar space; ITS, intrathecal space; IVD, intervertebral disc; VB, vertebral body.
Paramedian sagittal sonogram of the lumbosacral junction. The posterior surface of the sacrum is identified as a flat hyperechoic structure with a large acoustic shadow anteriorly. The dip or gap between the sacrum and the lamina of L5 is the L5–S1 intervertebral space, or the L5–S1 gap. The inset image is a matching sonogram from a water-based spine phantom showing the L5–S1 gap. AC, anterior complex; CE, cauda equina; ES, epidural space; ESM, erector spinae muscle; ITS, intrathecal space; LF, ligamentum flavum; PD, posterior dura.
Paramedian sagittal sonogram of the lumbosacral junction. The posterior surface of the sacrum is identified as a flat hyperechoic structure with a large acoustic shadow anteriorly. The dip or gap between the sacrum and the lamina of L5 is the L5–S1 intervertebral space, or the L5–S1 gap. The inset image is a matching sonogram from a water-based spine phantom showing the L5–S1 gap. AC, anterior complex; CE, cauda equina; ES, epidural space; ESM, erector spinae muscle; ITS, intrathecal space; LF, ligamentum flavum; PD, posterior dura.
Paramedian sagittal oblique sonogram of the lumbar spine at the level of the lamina showing the L3–4 and L4–5 interlaminar spaces. Note the hypoechoic epidural space (a few millimeters wide) between the hyperechoic ligamentum flavum and the posterior dura. The intrathecal space is the anechoic space between the posterior dura and the anterior complex. The cauda equina nerve fibers are also seen as hyperechoic longitudinal structures within the thecal sac. The hyperechoic reflections seen in front of the anterior complex are from the intervertebral disc (IVD). The inset image shows a matching computed tomography (CT) scan of the lumbosacral spine in the same anatomical plane as the US scan. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. AC, anterior complex; CE, cauda equina; ES, epidural space; ESM, erector spinae muscle; ILS, interlaminar space; ITS, intrathecal space; IVD, intervertebral disc; L3, lamina of L3 vertebra; L4, lamina of L4 vertebra; L5, lamina of L5 vertebra; LF, ligamentum flavum; PD, posterior dura.
Paramedian sagittal oblique sonogram of the lumbar spine at the level of the lamina showing the L3–4 and L4–5 interlaminar spaces. Note the hypoechoic epidural space (a few millimeters wide) between the hyperechoic ligamentum flavum and the posterior dura. The intrathecal space is the anechoic space between the posterior dura and the anterior complex. The cauda equina nerve fibers are also seen as hyperechoic longitudinal structures within the thecal sac. The hyperechoic reflections seen in front of the anterior complex are from the intervertebral disc (IVD). The inset image shows a matching computed tomography (CT) scan of the lumbosacral spine in the same anatomical plane as the US scan. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. AC, anterior complex; CE, cauda equina; ES, epidural space; ESM, erector spinae muscle; ILS, interlaminar space; ITS, intrathecal space; IVD, intervertebral disc; L3, lamina of L3 vertebra; L4, lamina of L4 vertebra; L5, lamina of L5 vertebra; LF, ligamentum flavum; PD, posterior dura.
Paramedian sagittal sonogram of the lumbar spine at the level of the articular processes (APs) of the vertebrae. Note the “camel hump” appearance of the APs. The inset image shows a corresponding computed tomography (CT) scan of the lumbosacral spine at the level of the APs. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. ESM, erector spinae muscle; IAP, inferior articular process; SAP, superior articular process; VB, vertebral body
Paramedian sagittal sonogram of the lumbar spine at the level of the articular processes (APs) of the vertebrae. Note the “camel hump” appearance of the APs. The inset image shows a corresponding computed tomography (CT) scan of the lumbosacral spine at the level of the APs. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. ESM, erector spinae muscle; IAP, inferior articular process; SAP, superior articular process; VB, vertebral body
Paramedian sagittal MRI section of the lumbar spine at the level of the lamina.
Paramedian sagittal MRI section of the lumbar spine at the level of the lamina.
Paramedian sagittal sonogram of the (A) lamina; (B) articular process; and (C) transverse process from a water-based spine phantom. Note the needle in contact with the lamina in (a), a method that was used to validate the sonographic appearance of the osseous elements in the phantom. The inset image in (a) illustrates the horse-head–like appearance of the laminae, and the inset image in (b) illustrates the camel-hump–like appearance of the articular processes. AP, articular process; SS, sagittal scan; TP, transverse process.
Paramedian sagittal sonogram of the (A) lamina; (B) articular process; and (C) transverse process from a water-based spine phantom. Note the needle in contact with the lamina in (a), a method that was used to validate the sonographic appearance of the osseous elements in the phantom. The inset image in (a) illustrates the horse-head–like appearance of the laminae, and the inset image in (b) illustrates the camel-hump–like appearance of the articular processes. AP, articular process; SS, sagittal scan; TP, transverse process.
Cadaver anatomical section showing the lumbosacral junction (L5–S1 gap) in the (A) transverse axis; (B) median (sagittal) axis and (C) paramedian sagittal axis. CE, cauda equina; ILS, interlaminar space; ITS, intrathecal space; IVD, intervertebral disc.
Cadaver anatomical section showing the lumbosacral junction (L5–S1 gap) in the (A) transverse axis; (B) median (sagittal) axis and (C) paramedian sagittal axis. CE, cauda equina; ILS, interlaminar space; ITS, intrathecal space; IVD, intervertebral disc.
Paramedian sagittal sections of the lumbosacral spine showing the lamina, interlaminar spaces, and spinal canal.(A)Three- dimensional (3D) reconstruction of high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Paramedian sagittal oblique sonogram through the L3–5 interlaminar spaces. (C) Paramedian sagittal cadaver anatomic section. AC, anterior complex; ES, epidural space; ILS, interlaminar space; ITS, intrathecal space; IVD, intervertebral disc; LF, ligamentum flavum; PD, posterior dura; VB, vertebral body.
Paramedian sagittal sections of the lumbosacral spine showing the lamina, interlaminar spaces, and spinal canal.(A)Three- dimensional (3D) reconstruction of high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Paramedian sagittal oblique sonogram through the L3–5 interlaminar spaces. (C) Paramedian sagittal cadaver anatomic section. AC, anterior complex; ES, epidural space; ILS, interlaminar space; ITS, intrathecal space; IVD, intervertebral disc; LF, ligamentum flavum; PD, posterior dura; VB, vertebral body.
Paramedian sagittal sections of the lumbar spine at the level of the articular processes (APs). (A) Three-dimensional reconstruction of a high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Paramedian sagittal cadaver anatomical section. (C) Paramedian sagittal sonogram.
Paramedian sagittal sections of the lumbar spine at the level of the articular processes (APs). (A) Three-dimensional reconstruction of a high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Paramedian sagittal cadaver anatomical section. (C) Paramedian sagittal sonogram.
Paramedian sagittal sonogram of the lumbar spine at the level of the transverse processes (TPs). Note the hyperechoic reflections of the TPs with their acoustic shadow that produces the “trident sign.” The psoas muscle (PM) is seen in the acoustic window between the transverse processes and is recognized by its typical hypoechoic and striated appearance. Part of the lumbar plexus is also seen as a hyperechoic shadow in the posterior part of the psoas muscle between the transverse processes of the L4 and L5 vertebrae. The inset image shows a corresponding computed tomography (CT) scan of the lumbosacral spine at the level of the TPs. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. ESM, erector spinae muscle; RPS, retroperitoneal space.
Paramedian sagittal sonogram of the lumbar spine at the level of the transverse processes (TPs). Note the hyperechoic reflections of the TPs with their acoustic shadow that produces the “trident sign.” The psoas muscle (PM) is seen in the acoustic window between the transverse processes and is recognized by its typical hypoechoic and striated appearance. Part of the lumbar plexus is also seen as a hyperechoic shadow in the posterior part of the psoas muscle between the transverse processes of the L4 and L5 vertebrae. The inset image shows a corresponding computed tomography (CT) scan of the lumbosacral spine at the level of the TPs. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. ESM, erector spinae muscle; RPS, retroperitoneal space.
Axial
Transverse MRI section of the lower lumbar spine through the interspinous space. Note the relationship of the articular process to the transverse process and the attachment of the ligamentum flavum to the lamina on either side. Also, note that the anterior epidural space is barely seen and that the anterior dura is very closely apposed to the posterior longitudinal ligament of the vertebra. ESM, erector spinae muscle; ITS, intrathecal space; IVC, inferior vena cava; PM, psoas major muscle; QLM, quadratus lumborum muscle; VB, vertebral body.
Transverse MRI section of the lower lumbar spine through the interspinous space. Note the relationship of the articular process to the transverse process and the attachment of the ligamentum flavum to the lamina on either side. Also, note that the anterior epidural space is barely seen and that the anterior dura is very closely apposed to the posterior longitudinal ligament of the vertebra. ESM, erector spinae muscle; ITS, intrathecal space; IVC, inferior vena cava; PM, psoas major muscle; QLM, quadratus lumborum muscle; VB, vertebral body.
Transverse sections of the lumbar spine at the level of the L4 spinous process (SP). (A) Transverse slice rendered from a high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Sonogram: transverse spinous process view. (B) Transverse cadaver anatomical section. ESM, erector spinae muscle; PM, psoas major muscle; QLM, quadratus lumborum muscle; VB, vertebral body.
Transverse sections of the lumbar spine at the level of the L4 spinous process (SP). (A) Transverse slice rendered from a high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Sonogram: transverse spinous process view. (B) Transverse cadaver anatomical section. ESM, erector spinae muscle; PM, psoas major muscle; QLM, quadratus lumborum muscle; VB, vertebral body.
Transverse sections of the lumbar spine at the level of the L3–4 interspinous space. (A) Transverse slice rendered from a high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Sonogram: transverse interspinous view. (C) Transverse cadaver anatomical section. AC, anterior complex; AP, articular process; ES, epidural space; ESM, erector spinae muscle; ITS, intrathecal sac; LF, ligamentum flavum; PM, psoas major muscle; QLM, quadratus lumborum muscle; TP, transverse process; VB, vertebral body.
Transverse sections of the lumbar spine at the level of the L3–4 interspinous space. (A) Transverse slice rendered from a high-resolution computed tomography (CT) scan dataset from the CIRS phantom. (B) Sonogram: transverse interspinous view. (C) Transverse cadaver anatomical section. AC, anterior complex; AP, articular process; ES, epidural space; ESM, erector spinae muscle; ITS, intrathecal sac; LF, ligamentum flavum; PM, psoas major muscle; QLM, quadratus lumborum muscle; TP, transverse process; VB, vertebral body.
Transverse sonogram of the lumbar spine with the transducer positioned directly over the L4 spinous process (transverse spinous process view). Note the acoustic shadow of the spinous process and lamina, which completely obscures the spinal canal and the neuraxial structures. The inset image shows a corresponding computed tomography (CT) scan of the lumbar vertebra. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. ESM, erector spinae muscle; SP, spinous process.
Transverse sonogram of the lumbar spine with the transducer positioned directly over the L4 spinous process (transverse spinous process view). Note the acoustic shadow of the spinous process and lamina, which completely obscures the spinal canal and the neuraxial structures. The inset image shows a corresponding computed tomography (CT) scan of the lumbar vertebra. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. ESM, erector spinae muscle; SP, spinous process.
Transverse sonogram of the lumbar spine with the transducer positioned such that the US beam is insonated through the interspinous space (transverse interspinous view). The epidural space, posterior dura, intrathecal space, and anterior complex are visible in the midline, and the articular process (AP) is visible laterally on either side of the midline. Note how the articular processes on either side are symmetrically located. The inset image shows a corresponding computed tomography (CT) scan of the lumbar vertebra. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. AC, anterior complex; ES, epidural space; ESM, erector spinae muscle; ITS, intrathecal space; PD, posterior dura; VB, vertebral body
Transverse sonogram of the lumbar spine with the transducer positioned such that the US beam is insonated through the interspinous space (transverse interspinous view). The epidural space, posterior dura, intrathecal space, and anterior complex are visible in the midline, and the articular process (AP) is visible laterally on either side of the midline. Note how the articular processes on either side are symmetrically located. The inset image shows a corresponding computed tomography (CT) scan of the lumbar vertebra. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. AC, anterior complex; ES, epidural space; ESM, erector spinae muscle; ITS, intrathecal space; PD, posterior dura; VB, vertebral body

Thoracic USS

Paramedian sagittal oblique sonogram of the lower thoracic spine. The acoustic window is relatively large; through it, the ligamentum flavum, posterior dura, epidural space, and anterior complex are clearly visible.
Paramedian sagittal oblique sonogram of the lower thoracic spine. The acoustic window is relatively large; through it, the ligamentum flavum, posterior dura, epidural space, and anterior complex are clearly visible.
Transverse interspinous sonogram of the midthoracic region. Visualization of the posterior dura and anterior complex can be very challenging in the midthoracic region due to the acute angulation of the spinous processes and requires cranial angulation of the US transducer.
Transverse interspinous sonogram of the midthoracic region. Visualization of the posterior dura and anterior complex can be very challenging in the midthoracic region due to the acute angulation of the spinous processes and requires cranial angulation of the US transducer.
Transverse interspinous sonogram of the upper thoracic spine.
Transverse interspinous sonogram of the upper thoracic spine.
Paramedian sagittal oblique sonogram of the midthoracic spine. The posterior dura (PD) and the anterior complex (AC) are visible through the narrow acoustic window. The inset image shows a corresponding computed tomography (CT) scan of the midthoracic spine. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. ILS, interlaminar space; LF, ligamentum flavum.
Paramedian sagittal oblique sonogram of the midthoracic spine. The posterior dura (PD) and the anterior complex (AC) are visible through the narrow acoustic window. The inset image shows a corresponding computed tomography (CT) scan of the midthoracic spine. The CT slice was reconstructed from a three-dimensional CT dataset from the author’s archive. ILS, interlaminar space; LF, ligamentum flavum.
Paramedian sagittal oblique sonogram of the upper thoracic spine. The posterior dura and the anterior complex are visible through the narrow acoustic window.
Paramedian sagittal oblique sonogram of the upper thoracic spine. The posterior dura and the anterior complex are visible through the narrow acoustic window.

Sacral USS

Transverse sonogram of the sacrum at the level of the sacral hiatus. Note the two sacral cornua and the hyperechoic sacrococcygeal ligament that extends between the two sacral cornua. (A) The hypoechoic space between the sacrococcygeal ligament and the posterior surface of the sacrum is the sacral hiatus. The image in (B) shows the sacral cornua from the water-based spine phantom; the image in (C) shows a three-dimensional (3D) reconstructed image of the sacrum at the level of the sacral hiatus from a 3D CT dataset from the author’s archive; and the image in (D) shows a transverse CT slice of the sacrum at the level of the sacral cornua.
Transverse sonogram of the sacrum at the level of the sacral hiatus. Note the two sacral cornua and the hyperechoic sacrococcygeal ligament that extends between the two sacral cornua. (A) The hypoechoic space between the sacrococcygeal ligament and the posterior surface of the sacrum is the sacral hiatus. The image in (B) shows the sacral cornua from the water-based spine phantom; the image in (C) shows a three-dimensional (3D) reconstructed image of the sacrum at the level of the sacral hiatus from a 3D CT dataset from the author’s archive; and the image in (D) shows a transverse CT slice of the sacrum at the level of the sacral cornua.
Sagittal sonogram of the sacrum at the level of the sacral hiatus. Note the hyperechoic sacrococcygeal ligament that extends from the sacrum to the coccyx and the acoustic shadow of the sacrum that completely obscures the sacral canal. The image in (B) shows the sacral hiatus from the water-based spine phantom; the image in (C) shows a three-dimensional (3D) reconstructed image of the sacrum at the level of the sacral hiatus from a 3D CT dataset from the author’s archive; and the image in (D) shows a sagittal CT slice of the sacrum at the level of the sacral cornua.
Sagittal sonogram of the sacrum at the level of the sacral hiatus. Note the hyperechoic sacrococcygeal ligament that extends from the sacrum to the coccyx and the acoustic shadow of the sacrum that completely obscures the sacral canal. The image in (B) shows the sacral hiatus from the water-based spine phantom; the image in (C) shows a three-dimensional (3D) reconstructed image of the sacrum at the level of the sacral hiatus from a 3D CT dataset from the author’s archive; and the image in (D) shows a sagittal CT slice of the sacrum at the level of the sacral cornua.

Reference