imaging of chest wall deformities (esti 2014)

8/18/2019 Imaging of Chest Wall Deformities (ESTI 2014)

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Imaging of Chest Wall Deformities

Award: Cum Laude

Poster No.: P-0110

Congress: ESTI 2014

Type: Educational Poster

Authors: B. Bhaludin, S. M. Mak, S. Naaseri, S. P. G. Padley; London/UK

Keywords: Congenital, Surgery, Education, Diagnostic procedure, CT,Thorax, Anatomy

DOI: 10.1594/esti2014/P-0110

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Learning objectives

- Identify common chest wall malformations and its pathology

- Understand common surgical correction procedures

- Identify post-surgical appearances

Background

Congenital chest wall deformities are due to anomalies of chest wall growth or

prominence, leading to sternal depression, or deformities related to failure of normal

spinal or rib development. Cross-sectional imaging allows appreciation of the involved

structures, assessment of displacement or deformity of adjacent but otherwise normalstructures, and differentiation between anatomical deformity and neoplasia. In some

cases, CT is also useful for surgical planning. In this pictorial essay, we discuss the

radiological features of congenital chest wall deformities and also illustrate pre and post-

surgical appearances for more conditions requiring surgical correction.

Imaging findings OR Procedure details

Pectus excavatum

Pectus excavatum (funnel chest) is the most common congenital deformity of the

sternum. Its incidence is approximately 1 in 400 births, afflicting men more than women. It

is uncommon among African Americans and Latinos (1). Although the majority of pectus

excavatum cases are congenital, around 15% of cases appear later during development

and these are frequently associated with abnormalities of connective tissues such as

Marfan and Ehlers-Danlos syndrome (2). Pectus excavatum is characterised by the

presence of deep sternal depression causing the ribs on each side to protrude more

anteriorly than the sternum (3). The sternal and cartilaginous depression causes a

reduction in the prevertebral space, which gives rise to a leftward displacement and axial

rotation of the heart. Other features include decreased density of the heart, an indistinct

right heart border, horizontal posterior ribs, and vertical anterior ribs (4). These features

can be seen on chest radiographs ( Fig. 1 on page 5 ). While pectus excavatum

is usually detected clinically, CT maybe used to quantify the severity of the deformity

especially when surgical intervention is being considered ( Fig. 2 on page 6, Fig. 3


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on page 6, Fig. 4 on page 7, Fig. 5 on page 8 ). Severity may be guided

using the Haller index, which is based on the ratio of lateral and antero-posterior thoracic

diameters ( Fig. 6 on page 9 ). Haller et. al. have suggested that an index of greater

than 3.25 would require surgical correction (5). In normal children the Haller index ranges

from 1.9 to 2.7. The Haller index for children under 2 years of age is markedly lower than

that in older children, and girls between the ages of 0-6 and 12-18 years may have a

higher index than their male counterparts (6). Different phases of respiration may affect

the Haller index, and may yield a value significantly lower during inspiration. This reflectsadvances in CT scanner technology, in comparison to Haller's day, when scans were

performed over multiple breath holds (7).

Pectus excavatum is easily diagnosed in childhood, but is commonly ignored. Recent

literature suggest that many patients experience detrimental cardiovascular and

respiratory physiological changes as they mature. The exact reason remains elusive,

but this maybe due to decreasing chest wall compliance with increasing age (8). Pectus

excavatum correction may improve the quality of life in patients, both physically and

psychosocially (9).

The two most common surgical procedures used to correct pectus excavatum deformities

are the Nuss procedure and the modified Ravitch procedure. The Nuss procedure is also

known as minimally invasive repair of pectus excavatum (MIRPE).

The Nuss procedure is a minimally invasive procedure which consists of implanting two

curved retrosternal metallic bars, inserted through small lateral incisions ( Fig. 7 on page

10 , Fig. 8 on page 11 ) (2). This procedure allows immediate correction of the

deformity since in childhood, chest wall structures are less rigid. The Nuss bar is usually

removed after 3 years. The advantage of the Nuss procedure is its cosmetic advantage,with smaller skin incisions which maybe more acceptable. However, it is associated with

a higher complication rate and cost when compared to the modified Ravitch (10).

The original Ravitch procedure is a radical repair, freeing the sternum from all restrictions.

He resected all sternal attachments and the whole length of the deformed costal

cartilages. The sternum is then bent sharply anteriorly, fracturing the posterior cortical

lamella in the process (11). However, without external traction, which was popular then,

his technique had an increased recurrence rate. The modified Ravitch procedure is more

extensive when compared to the Nuss procedure, and involves the resection of the

deformed anterior costal cartilages and then fixation of the sternum into a more normal

position using metal bars ( Fig. 9 on page 12 , Fig. 10 on page 13 ) (2). The metal

bars are wired to the adjacent sternum and are typically removed after 2 years.


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Chest radiographs are useful to visualise the position of the Nuss and Ravitch bars, and

to detect any complications. The complications include wound infections, haematomas,

bar migration and pneumothorax ( Fig. 1 on page 5 , Fig. 10 on page 13, Fig. 11

on page 13 , Fig. 12 on page 14 ).

Pectus carinatum

Pectus carinatum (pigeon chest) is the second most common congenital deformity of the

sternum, with its incidence estimated to be 5 times lower than pectus excavatum (12).

It is characterised by an abnormal anterior protrusion of the sternum and costochondral

joints ( Fig. 13 on page 15 , Fig. 14 on page 16 , Fig. 15 on page 18 , Fig. 16 on

page 18 , Fig. 17 on page 19 , Fig. 18 on page 20 ). Pectus carinatum can be

classified according to the location of the protrusion. Type 1 (inferior or chondo-gladiolar),

which is the most frequent type, involves protrustion of the inferior or mid-sternum, while

Type 2 (superior or chondro-manubrial) involves the manubrium or superior aspect of

the sternum (2). Surgical correction is reserved for moderate or severe deformities. Initial

lateral chest radiographs will demonstate sternal protrusion, but subsequent imagingwith CT allows quantification of the severity using the Haller index, similar itse use in

pectus excavatum (13). A study quoted the average Haller index of patients requiring

surgical correction as 1.8 (14). In pectus carinatum, a lower index indicates more severe

deformity. Surgical correction of pectus carinatum is similar to pectus excavatum in which

the Ravitch and Nuss procedures are modified appropriately to correct the protruding

defect (15). Recent literature has suggested the increasing popularity of non-invasive

bracing as an alternative treatment (16).

Pectus arcuatum

Pectus arcuatum means 'wave-like' chest deformity and it is a rare condition with an

unknown aetiology. The term is used to describe mixed deformities which contain both

excavatum and carinatum either along a longitudinal or axial axis, and is also known

as a pouter pigeon chest (16) ( Fig. 19 on page 21 ). It contains a protrusion at

the upper part of the sternum involving the manubriosternal junction and the second to

fifth rib cartilages, with premature sternal ossification (1). There may be an associated

excavatum deformity at the lower sternum in up to one third of cases. The pouter

pigeon chest can be appreciated on sagittal CT images although traditionally lateral chest

radiography have been used. Imaging with CT allows calculation of the angle of Louis in

order to determine the severity of the deformity. The normal angle of Louis is between

145-175°. Surgical correction is recommended in patients with an angle of #130° (18).

Surgical correction involves a wide wedge transverse sternotomy at the angle of Louis

and subperichondrial resection of the adjacent costal cartilages (1).


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Poland syndrome

Poland syndrome is a non-genetic congenital abnormality and the aetiology is unknown. It

is characterised by partial or total absence of the pectoral muscles and is most commonly

unilateral (2). There is a range of breast involvement, varying from mild hypoplasia to

complete absence (amastia). Poland's syndrome is associated with rib cage anomalies

in up to 60% of cases including aplasia or hypoplasia of the ribs (13). Other associationsinclude hand involvement (varying from mild shortening of the phalanges to syndactyly),

lung herniation and dextrocardia (17).

On chest radiography, the affected side appears of increased transradiancy due to

reduction in overlying soft tissues. CT is useful to demonstrate the absence of the greater

pectoral muscle and any associated musculoskeletal anomalies of the chest wall ( Fig.

20 on page 22 , Fig. 21 on page 23 ) (3). Surgical correction is only required if there

is a rib defect large enough to cause a lung herniation or if there are concerns of injury

to the heart or lungs (19). Adolescent females with amastia may also require cosmetic

reconstruction.

Rib Exostosis

Rib osteochondromas can be solitary or associated with multiple hereditary exostoses.

Up to 50% of patients with multiple hereditary exostoses may have rib osteochondromas

(20). Exostoses projecting outwards maybe palpable, whereas internal exostoses may

be an incidental finding on imaging only (21) ( Fig. 22 on page 24 , Fig. 23 on page

25 , Fig. 24 on page 26 ).

Normal variation

There are normal asymptomatic variations of the anterior chest wall that maybe incidental

on imaging. They may include a tilted sternum, convex anterior ribs or prominent costal

cartilages (22).

Images for this section:


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Fig. 1: A 24 year old female patient presented with pectus excavatum. Three consecutive

radiographs demonstrates subsequent corrective surgeries. (a) Pre-operative chest

radiograph. (b) The patient initially underwent a Nuss procedure. Note the post-operative

right sided pneumothorax and subcutaneous surgical emphysema. (c) She subsequently

needed the Nuss bar removed, which was then exchanged for a Ravitch bar.

Fig. 2: (a) Axial CT of the same 24 year old patient demonstrating pectus excavatum.

Note the sternal depression and tilting, with leftward displacement of the heart. (b) Sagittal

reconstructions.


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Fig. 3: 3D surface reconstructions of the same 24 year old patient, showing sternal

depression and tilting.


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Fig. 4: 3D reconstruction of the same 24 year old patient with pectus excavatum,

demonstrating anterior chest wall depression.


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Fig. 5: 3D cutaway of the same 24 year old patient with pectus excavatum.


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Fig. 6: Haller index of the same 24 year old patient (ratio of A to B).


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Fig. 7: CT of a 37 year old male patient with a Nuss bar deep to the sternum.


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Fig. 8: 3D reconstructions of the same 37 year old patient with a Nuss bar.


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Fig. 9: 3D surface reconstructions of a 21 year old patient presenting with pectus

excavatum.

Fig. 10: (a)Pre-operative CT of the same 21 year old female patient. (b) Post modified

Ravitch procedure CT. The right anterior end of the Ravitch bar had migrated inferiorly

and invaginated the lung parenchyma. The bar was subsequently removed.


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Fig. 11: 51 year old man with a previous modified Ravitch procedure presented with

chest tightness. An initial chest radiograph demonstrated migration of the Ravitch bar

inferiorly and eccentric to the right.


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Fig. 12: 3D surface reconstruction of the same 51 year old patient with migration of the

Ravtich bar.


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Fig. 13: Radiograph of a 34 year old patient with pectus carinatum. The PA appearances

are almost normal, but the lateral CT reconstructions will demonstrate the "pigeon chest"

much clearer.


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Fig. 17: 24 year old male patient with asymmetrical pectus carinatum affecting the right

costal cartilages


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Fig. 18: 3D reconstructions of the same 24 year old patient with asymmetrical pectus

carinatum.


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Fig. 19: A female patient with mixed deformity consisting of both pectus excavatum and

carinatum, creating a "rolling" appearance.


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Fig. 20: Poland syndrome with absence of right pectoral muscles causing chest wall

asymmetry.


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Fig. 21: MIP images of the same patient with Poland syndrome. In addition to the absence

of right sided pectoral muscles, there is also abnormal sternal protrusion.


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Fig. 22: Right 5th rib exostosis directed into the thoracic cavity.


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Fig. 23: Coronal reformats of the same patient with exostosis of the right 5th rib.


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Fig. 24: 3D reconstruction of the same patient with a right 5th rib bony exostosis.


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Conclusion

In summary, there is a variety of congenital conditions affecting the chest wall

which commonly presents at birth or childhood. We have reviewed the characteristic

radiographic and CT appearances of these conditions. Familiarity with the different

congenital chest wall deformities allows accurate diagnosis and provides helpful

information for appropriate patient treatment.

References

1. Fokin A, Steuerwald N, Ahrens W. Anatomical, histologic, and geneticcharacteristics of congenital chest wall deformities. Semin ThoracCardiovasc Surg.2009; 21:44-57.

2. Torre M, Rapuzzi G, Jasonni V. Chest Wall Deformities: An Overview on

Classification and Surgical Options. In: Cardoso P, editor. Topics in ThoracicSurgery.

3. Jeung M-Y, Gangi A, Gasser B et al. Imaging of Chest Wall Disorders.RadioGraphics. 1999; 19:617-37.

4. Dahnert W. Radiology Review Manual. Lippincott Williams & Wilkins.5. Haller J, Kramer S, Lietman S. Use of CT scans in selection of patients

for pectus excavatum surgery: a preliminary report. J Pediatr Surg. 1987;22:904-6.

6. Daunt S, Cohen J, Miller S. Age-related normal ranges for the Haller index inchildren.Pediatr Radiol2004; 34: 326-30.

7. Birkemeier K, Podberesky D, Salisbury S et al. Breathe In... Breathe Out...

Stop Breathing: Does Phase of Respiration Affect the Haller Index inPatients With Pectus Excavatum? AJR 2011; 197:934-939.

8. Jaroszewski D,NotricaD,McMahonL. Current Management of PectusExcavatum: A Review and Update of Therapy and TreatmentRecommendations.J Am Board Fam Med 2010; 23:230-239

9. Kelly R, Cash T, Shamberger R et al. Surgical Repair of Pectus ExcavatumMarkedly Improves Body Image and Perceived Ability for Physical Activity:Multicenter StudyPediatrics 2008;122:1218 -1222.

10. Antonoff M, Erickson A, Hess D. When patients choose: comparisonof Nuss, Ravitch, and Leonard procedures for primary repair of pectus

excavatum. J Pediatr Surg 2009; 44:1113-1118.11. Ravitch M. The Operative Treatment of Pectus Excavatum.Am J Surg.1961;19:588-597.

12. Colombani P. Preoperative assessment of chest wall deformities. SeminThorac Cardiovasc Surg. 2009; 21:58-63.

13. Goretsky M, Kelly R, Croitoru D. Chest Wall anomalies: Pectus Excavatumand Pectus Carinatum. Adolesc Med Clin. 2004; 15: 455-71.


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14. Fonkalsrud E, DeUgarte D, Choi E. Repair of Pectus Excavatum andCarinatum Deformities in 116 adults. Ann Surg. 2002; 238: 304-314

15. Blanco F, Elliott S, Sandler A. Management of Congenital Chest WallDeformities. Semin Plast Surg. 2011; 25:107-16.

16. Emil S, Laberge J, Sigalet et al. Pectus carinatum treatment in Canada:current practices. J Pediatr Surg. 2012; 47:862-6.

17. Schwabegger A. Special techniques in pectus arcuatum and mixeddeformities. In: Prof AHSM, MSc, Asso, editor. Congenital Thoracic Wall

Deformities. Springer Vienna; 201118. Franco K, Putnam J. Advanced Therapy in Thoracic Surgery. Hamilton,

Ontario: BC Decker19. Puri P, Hollwarth M. Pediatric Surgery: Diagnosis and Management.

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normal variants and diseases that involve the ribs. RadioGraphics 1999;19:1125-1142.

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