The Neuroradiology Journal 21: 244-247, 2008
www. centauro. it
Swimmer’s CT Angiography of Thoracic Outlet Syndrome A Case Report R. MARINA U.O. Neuroradiologia. Ospedale S. Gerardo, Università Milano Bicocca; Monza, Italy
Key words: CT angiography, thoracic outlet syndrome
SUMMARY – A pictorial essay is presented where the so-called swimmer’s position is employed as a postural provocative maneuver to enhance the anatomic characteristics of the thoracic outlet in a symptomatic patient. Helical CT angiography showed severe axillary artery compression due to significant narrowing of the costoclavicular space.
The neurovascular compression syndromes occurring at the level of the thoracic outlet refer to disorders attributed to compression of vascular structures (i.e., the subclavian and axillary arteries and veins and the brachial plexus fibers) in their course within this anatomic space. Provocative positioning tests are commonly used in the diagnosis of thoracic outlet syndrome, searching for a reproduction of the symptoms or obliteration of pulses when the arm is placed in the provocative position (Adson’s maneuver). Since a positive result may also be obtained in normal subjects, these clinical tests need to be supplemented with other diagnostic tools. In an attempt to provide clinicians with pathophysiologic information interest has been shown in the helical CT evaluation of this region. In late 2000 Remy-Jardin et al. presented CT angiography for in vivo evaluation of the functional anatomy of the thoracic outlet. They analyzed the anatomic characteristics of the three compartments (i.e., the interscalene triangle, the costoclavicular space and the subcoracoid tunnel) of the thoracic outlet before and after the postural maneuver. The most important findings concerned the postural changes observed at the level of the costoclavicular space in the transverse arch of the subclavian artery, with a posterior displacement of the axillary artery during the postural maneuver. They stressed however a few limitations of their study: pa244
tients were examined in the supine position on helical CT angiography, whereas they are clinically examined in the erect position, without a strict standardization of the positional maneuver. In late 2004 Kane et al. introduced the socalled swimmer’s CT to improve imaging of the lower neck and thoracic inlet. The maneuver consists of a static supine simulation of backstroke while swimming 1-4. Case Report A 21-year-old female clinically suspected to have left thoracic outlet syndrome was studied with helical CT angiography in the supine swimmer’s position as a provocative maneuver. Examination was obtained at normal breath on a Philips Brilliance CT scanner 16 Power Configuration while the patient was lying in the supine position with the symptomatic arm elevated above the head and controlateral rotation of the head, which remained extended while the asymptomatic arm was lying alongside the body. This position combined the features of two maneuvers currently obtained in the clinical evaluation of thoracic outlet syndrome – namely, Adson’s and Wright’s maneuvers. The surveyed volume extended from the supra-orbital skull to the lower extremity of the
R. Marina
Swimmer’s CT Angiography of Thoracic Outlet Syndrome
Figure 1 Artist’s drawing showing the anatomy of neurovascular compression in thoracic outlet syndrome (from Adam. com).
Figure 2 Angiographic demonstration of the left axillary artery in costoclavicular space during provocative Adson’s maneuver (worldwide web source).
Figure 3 Scout view of the swimmer’s CT in our patient.
245
Swimmer’s CT Angiography of Thoracic Outlet Syndrome
R. Marina
Figure 4 Swimmer’s CT angiography. Volume-rendered global image before customized virtual clipping.
Figure 5 Three dimensional shaded-surface reconstruction, axial view, clipped volume from C7 to the second rib. Stenosis of left axillary artery, overestimated as a flow arrest at the inlet of the costoclavicular space.
third rib. The scanning parameters consisted of 120 kVp, 140 mAs/slice with a 0.5 s rotation time, thickness 2 mm with 1 mm increment; 16×0.75 collimation with a pitch of 1.438. 268 images were acquired in 8.437 s. The given ra246
diation dose was CTDI 10.9 mGy and DLP 316.0 mGy*cm. The injection protocol was administration of consecutive boluses of 30% contrast agent and saline at a rate of 5 ml/s with a dual injector. The contrast material was injected via
www. centauro. it
The Neuroradiology Journal 21: 244-247, 2008
A
B
Figure 6 A) Anteroposterior maximum intensity projection. B) Sagittal reformation. Rat-tail like narrowing, with cirsoid course, of the left axillary artery (ax) at the thoracic inlet (A) and compression of the vessel (arrow) at the costoclavicular space (B).
venous access in the symptomatic arm also to evaluate the venous side of the thoracic outlet. A series of sagittal reformations was obtained from the medial portion of the lower cervical vertebrae to the head of the humerus. A series of anteroposterior maximum intensity projections and three dimensional shaded-surface were reconstructed to provide an overall view of the bony and vascular structures of each thoracic outlet. Volume-rendered images of the thoracic outlet were created to provide simultaneous analysis of the bones and arteries on a superoinferior image. The data from multiplanar MIP and 3D reconstructed images were positive for a diagnosis of thoracic outlet syndrome due to a pos-
terior displacement and severe compression of the left axillary artery in the costoclavicular space. Conclusion Swimmer’s CT angiography can be employed in patients with the symptoms of thoracic outlet sindrome, where clinical examination is indicative or doubtful. This technique is the only non invasive means of depicting vascular stenosis, as well as anomalies of the surrounding musculoskeletal structures. In addition, radiologists can provide surgeons with an objective means of evaluating postoperative results.
References 1 Remy-Jardin M, Remy J, Masson P et Al: Helical CT angiography of thoracic outlet syndrome: functional anatomy. Am J Roentgenol 174: 1667-1674, 2000. 2 Remy-Jardin M, Remy J, Masson P et Al: CT angiography of thoracic outlet syndrome: evaluation of imaging protocols for the detection of arterial stenosis. Journal of CAT 24: 349-361, 2000. 3 Kane AG, Reilly KC and Murphy TF: Swimmer’s CT: improved imaging of the lower neck and thoracic inlet. Am J Neuroradiol 25: 859-862, 2004.
4 Bilbey JH, Muller NL, Connell DG et Al: Thoracic outlet syndrome: evaluation with CT. Radiology 171: 381384, 1989. Roberto Marina, MD Radiodiagnostica Azienda Ospedaliera S. Gerardo via G. Donizetti, 106 - 20052 Monza, Italy Tel.: +39 347 1163914 E-mail: [email protected]
247
www. centauro. it
Swimmer’s CT Angiography of Thoracic Outlet Syndrome A Case Report R. MARINA U.O. Neuroradiologia. Ospedale S. Gerardo, Università Milano Bicocca; Monza, Italy
Key words: CT angiography, thoracic outlet syndrome
SUMMARY – A pictorial essay is presented where the so-called swimmer’s position is employed as a postural provocative maneuver to enhance the anatomic characteristics of the thoracic outlet in a symptomatic patient. Helical CT angiography showed severe axillary artery compression due to significant narrowing of the costoclavicular space.
The neurovascular compression syndromes occurring at the level of the thoracic outlet refer to disorders attributed to compression of vascular structures (i.e., the subclavian and axillary arteries and veins and the brachial plexus fibers) in their course within this anatomic space. Provocative positioning tests are commonly used in the diagnosis of thoracic outlet syndrome, searching for a reproduction of the symptoms or obliteration of pulses when the arm is placed in the provocative position (Adson’s maneuver). Since a positive result may also be obtained in normal subjects, these clinical tests need to be supplemented with other diagnostic tools. In an attempt to provide clinicians with pathophysiologic information interest has been shown in the helical CT evaluation of this region. In late 2000 Remy-Jardin et al. presented CT angiography for in vivo evaluation of the functional anatomy of the thoracic outlet. They analyzed the anatomic characteristics of the three compartments (i.e., the interscalene triangle, the costoclavicular space and the subcoracoid tunnel) of the thoracic outlet before and after the postural maneuver. The most important findings concerned the postural changes observed at the level of the costoclavicular space in the transverse arch of the subclavian artery, with a posterior displacement of the axillary artery during the postural maneuver. They stressed however a few limitations of their study: pa244
tients were examined in the supine position on helical CT angiography, whereas they are clinically examined in the erect position, without a strict standardization of the positional maneuver. In late 2004 Kane et al. introduced the socalled swimmer’s CT to improve imaging of the lower neck and thoracic inlet. The maneuver consists of a static supine simulation of backstroke while swimming 1-4. Case Report A 21-year-old female clinically suspected to have left thoracic outlet syndrome was studied with helical CT angiography in the supine swimmer’s position as a provocative maneuver. Examination was obtained at normal breath on a Philips Brilliance CT scanner 16 Power Configuration while the patient was lying in the supine position with the symptomatic arm elevated above the head and controlateral rotation of the head, which remained extended while the asymptomatic arm was lying alongside the body. This position combined the features of two maneuvers currently obtained in the clinical evaluation of thoracic outlet syndrome – namely, Adson’s and Wright’s maneuvers. The surveyed volume extended from the supra-orbital skull to the lower extremity of the
R. Marina
Swimmer’s CT Angiography of Thoracic Outlet Syndrome
Figure 1 Artist’s drawing showing the anatomy of neurovascular compression in thoracic outlet syndrome (from Adam. com).
Figure 2 Angiographic demonstration of the left axillary artery in costoclavicular space during provocative Adson’s maneuver (worldwide web source).
Figure 3 Scout view of the swimmer’s CT in our patient.
245
Swimmer’s CT Angiography of Thoracic Outlet Syndrome
R. Marina
Figure 4 Swimmer’s CT angiography. Volume-rendered global image before customized virtual clipping.
Figure 5 Three dimensional shaded-surface reconstruction, axial view, clipped volume from C7 to the second rib. Stenosis of left axillary artery, overestimated as a flow arrest at the inlet of the costoclavicular space.
third rib. The scanning parameters consisted of 120 kVp, 140 mAs/slice with a 0.5 s rotation time, thickness 2 mm with 1 mm increment; 16×0.75 collimation with a pitch of 1.438. 268 images were acquired in 8.437 s. The given ra246
diation dose was CTDI 10.9 mGy and DLP 316.0 mGy*cm. The injection protocol was administration of consecutive boluses of 30% contrast agent and saline at a rate of 5 ml/s with a dual injector. The contrast material was injected via
www. centauro. it
The Neuroradiology Journal 21: 244-247, 2008
A
B
Figure 6 A) Anteroposterior maximum intensity projection. B) Sagittal reformation. Rat-tail like narrowing, with cirsoid course, of the left axillary artery (ax) at the thoracic inlet (A) and compression of the vessel (arrow) at the costoclavicular space (B).
venous access in the symptomatic arm also to evaluate the venous side of the thoracic outlet. A series of sagittal reformations was obtained from the medial portion of the lower cervical vertebrae to the head of the humerus. A series of anteroposterior maximum intensity projections and three dimensional shaded-surface were reconstructed to provide an overall view of the bony and vascular structures of each thoracic outlet. Volume-rendered images of the thoracic outlet were created to provide simultaneous analysis of the bones and arteries on a superoinferior image. The data from multiplanar MIP and 3D reconstructed images were positive for a diagnosis of thoracic outlet syndrome due to a pos-
terior displacement and severe compression of the left axillary artery in the costoclavicular space. Conclusion Swimmer’s CT angiography can be employed in patients with the symptoms of thoracic outlet sindrome, where clinical examination is indicative or doubtful. This technique is the only non invasive means of depicting vascular stenosis, as well as anomalies of the surrounding musculoskeletal structures. In addition, radiologists can provide surgeons with an objective means of evaluating postoperative results.
References 1 Remy-Jardin M, Remy J, Masson P et Al: Helical CT angiography of thoracic outlet syndrome: functional anatomy. Am J Roentgenol 174: 1667-1674, 2000. 2 Remy-Jardin M, Remy J, Masson P et Al: CT angiography of thoracic outlet syndrome: evaluation of imaging protocols for the detection of arterial stenosis. Journal of CAT 24: 349-361, 2000. 3 Kane AG, Reilly KC and Murphy TF: Swimmer’s CT: improved imaging of the lower neck and thoracic inlet. Am J Neuroradiol 25: 859-862, 2004.
4 Bilbey JH, Muller NL, Connell DG et Al: Thoracic outlet syndrome: evaluation with CT. Radiology 171: 381384, 1989. Roberto Marina, MD Radiodiagnostica Azienda Ospedaliera S. Gerardo via G. Donizetti, 106 - 20052 Monza, Italy Tel.: +39 347 1163914 E-mail: [email protected]
247
