developmental lung malformations in children

Developmental Lung Malformations in Children

Recent Advances in Imaging Techniques, Classification System,and Imaging Findings

Paul G. Thacker, MD,* Gary R. Schooler, MD,w Michael J. Caplan, MD,zand Edward Y. Lee, MD, MPHy

Abstract: Congenital lung anomalies represent a diverse group ofdevelopmental malformations of the lung parenchyma, arterialsupply, and venous drainage, which may present anywhere fromthe prenatal period through adulthood. It is imperative for radio-logists to be aware of imaging techniques and imaging appearanceof these anomalies across the pediatric age range. This reviewpresents the spectrum of these lesions that are often encountered indaily clinical practice. Each anomaly is discussed in terms ofunderlying etiology, clinical presentation, and imaging character-ization with emphasis on the most up-to-date research and treat-ment. Knowledge of these areas is essential for accurate, timelydiagnosis, which aids in optimizing patient outcomes.

Key Words: congenital lung anomalies, prenatal imaging, com-

puted tomography, magnetic resonance imaging

(J Thorac Imaging 2015;30:29–45)

LEARNING OBJECTIVESAfter completing this CME activity, physicians should

be better able to:1. Distinguish the most commonly encountered congenital

lung anomalies encountered in thoracic imaging2. Analyze the most common anatomic locations of con-

genital lung anomalies3. State other developmental anomalies associated with

congenital lung anomalies

Congenital lung anomalies (CLA) have an annualincidence of 32 to 42/100,000 population1–3 and represent aheterogenous group of developmental abnormalities yield-ing a wide variety of imaging and clinical manifestations.Many will be detected during early childhood, whereasothers will remain occult into adulthood. It is thus imper-ative for radiologists to be cognizant of the proper imaging

techniques and imaging appearances for each lesion togarner timely and accurate evaluation and diagnosis.

This article provides practical imaging techniques inthe evaluation of CLA. In addition, this article includes up-to-date information of underlying etiology, clinical pre-sentation, characteristic imaging findings, and currenttreatments. Future directions, which can lead to improvedunderstanding and evaluation of CLA, are also discussed.

PRACTICAL IMAGING TECHNIQUES ANDEVALUATION

Detailed descriptions of the imaging characteristics foreach lesion are provided under the respective sections.However, usefulness analysis and description of the availableimaging modalities are informative. Four modalities arecurrently used for the imaging evaluation of CLA, inclu-ding chest radiography (CR), ultrasound (US), computedtomography (CT), and magnetic resonance imaging (MR).

CRDespite CLA often being detected by prenatal US or

MR, CR remains the initial imaging modality for the detec-tion and characterization of these lesions postnatally, even ifpatients are asymptomatic. If obtainable, posteroanterior andlateral radiographs are the technique of choice. However, in avery young patient, a lateral radiograph may not be feasible,and a single anteroposterior radiograph must suffice.

Radiographic findings vary depending on the lesiontype and size. However, general principles can provide aclue to the presence of a CLA and include: (1) focal opacity/mass; (2) focal lucency; (3) thoracic asymmetry; (4) vascularabnormalities; (5) airway anomalies; and (6) other con-genital lesions involving the spinal column, heart, andgastrointestinal tract.2,3 The presence of 1 or a combinationof these findings may help in further imaging recom-mendations or sometimes point to a definitive diagnosis.

USUS has become an integral tool of maternofetal med-

icine and is the modality of choice for fetal screening. Fetallungs appear uniformly hyperechoic compared with theliver. Focal increased areas of echogenicity or cyst mayprovide an early clue to the presence of an underlying CLA(Fig. 1). However, the first clue is often cardiomediastinalshift with the heart serving as an important landmark in thefetal chest, occupying a thoracic volume of 25% to 30% onthe 4-chamber view.4 Postnatally, US provides a widelyavailable and radiation-free modality for CLA evaluation,usually following initial radiographs.

Optimal acoustic windows in the neonate and youngchild include the parasternal, transsternal, and intercostal

*Assistant Professor of Radiology and Radiological Science;zAssociate Professor of Pathology and Laboratory Medicine,Medical University of South Carolina, Charleston, SC; wPediatricRadiology Fellow, Department of Radiology; and yChief of Divi-sion of Thoracic Imaging, Director of Magnetic Resonance Imag-ing, Department of Radiology, Boston Children’s Hospital andHarvard Medical School, Boston, MA.

All authors and staff in a position to control the content of this CMEactivity and their spouses/life partners (if any) have disclosed thatthey have no financial relationships with, or financial interests in,any commercial organizations pertaining to this educationalactivity.

Correspondence to: Edward Y. Lee, MD, MPH, Chief of Division ofThoracic Imaging, Director of Magnetic Resonance Imaging,Department of Radiology, Boston Children’s Hospital and HarvardMedical School, 300 Longwood Ave. Boston, MA 02115 (e-mail:[email protected]).Copyright r 2014 by Lippincott Williams & Wilkins

REVIEW AND SA-CME ARTICLE

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mailto:[email protected]

approaches utilizing a high-resolution 10 to 15MHz linear-array transducer.5 At least 2 orthogonal planes are acquired,with Doppler used for aberrant vascularity evaluation. Withincreased patient age, US becomes limited because of decreasedsonographic windows, and US may simply add to increasedcost while providing little additional diagnostic information.

CTAfter CRs, CT, specifically multidetector CT (MDCT),

is generally recommended in CLA evaluation. MDCTadvantages include fast acquisition times, high spatial res-olution, and exquisite detail of multiplanar (MPR) and 3-dimensional (3D) reconstructions.2,6 Disadvantages includeits relatively high doses of radiation and respiratory motionin the subset of children unable to cooperate with breath-holding. These disadvantages have progressively decreasedwith newer-generation scanners and low-dose techniques.

Optimal scan coverage is of utmost importance forCLAs. Generally, coverage extends from the thoracic inletto the diaphragm. In specific situations, for example,extralobar sequestration and type 2 pulmonary arteryslings, coverage may be extended. Technical parameters willvary on the basis of the CT scanner model, patient size, andimaging protocol. However, some general parameters fortube current, kilovoltage, collimation, and table speed areworth considering. Given the wide range of pediatricpatient sizes, both tube current and kilovoltage are variedon the basis of patient weight. For patients <10kg, acurrent of 40mA is used, whereas patients Z50 kg receivebetween 100 and 120mA. For patients <50 kg, 80 kVp isused, whereas in larger patients, a kVp of 100 to 120 may beneeded. Table speeds of <1 second are routinely used.Collimation is dependent on detector number but is gen-erally 0.5 to 0.6mm for 64-detector row scanners.6

In addition to modulating mA and kVp, recentresearch has demonstrated that newer reconstruction algo-rithms, for example, adaptive statistical iterative recon-struction and model-based iterative reconstruction, canfurther reduce radiation exposure while yielding equivalentor superior image quality to filter back projection.7 In recentpediatric studies by Singh et al8 and Mieville et al,9 46.4%

dose reduction was achieved with adaptive statistical iter-ative reconstruction with equivalent image quality to filteredback projection. Although neither study evaluated patientswith CLA, it can likely be assumed that dose reductionusing iterative reconstruction can be achieved without sac-rificing diagnostic quality.

After the initial axial data set is acquired, 3D refor-mations of the lung, airway, and vascularity may be con-structed. Axial images are highly accurate for the diagnosis,location, associated mass effect, and anomalous arterialsupply of CLAs. In addition, MPR and 3D reconstructionshave been recently demonstrated to provide added value forCLA associated with anomalous veins.10 As such, theseshould be routinely generated in many cases.

MRGiven lack of ionizing radiation and high tissue-con-

trast resolution, MR provides an alternative for the evalu-ation of vascular and solid constituents of CLAs. However,MR is limited in its ability to depict lung parenchymalanomalies and, as such, serves only a secondary role to CT.Despite limitations, MR may be utilized in situations inwhich the risks of CT radiation outweigh the benefits, suchas in the prenatal period.

Prenatal MR is often requested after an abnormalscreening US. Small CLAs do not need further advancedimaging in the prenatal period. Very large lesions resultingin pulmonary hypoplasia and pulmonary compromise oftendo, as residual lung volume calculation has been shown todirectly correlate with patient prognosis.11

T2-weighted single-shot rapid-acquisition sequencesrepresent the workhorse of fetal MR imaging, providingexquisite anatomic and pathologic detail (Fig. 2). Given thefluid-filled fetal respiratory tree, the trachea, bronchi, andthe lungs are T2 hyperintense relative to the chest wall.Alveolar fluid production increases with advancing gesta-tional age, further increasing lung T2 hyperintensity. If anabnormality is detected, images with smaller fields of vieware acquired. T1-weighted images are routinely obtainedbut may be suboptimal given the time required foracquisition. Spoiled gradient-echo imaging seems to be themost beneficial of the T1 sequences available.2,3

Postnatal MR protocols are tailored to the suspectedlesion type. For both vascular and nonvascular CLAs, axialT1 or double inversion recovery, axial and coronal T2 fastrelaxation fast spin echo, coronal 3D angiography, post-gadolinium axial and coronal T1-weighted images with fatsaturation, and spoiled gradient-recalled echo after gado-linium are often acquired. For vascular lesions, additionalsagittal 3D spoiled gradient-echo angiographic and 3-planefast spin echo double inversion recovery sequences areadded.

Recent studies have introduced the concept of unenhancedfast-imaging protocols for pediatric thoracic evaluation.12,13 In aprospective study comparing unenhanced fast-imaging MRversus contrast-enhancedMDCT in 71 children, Gorkem et al12

demonstrated MR to have an accuracy of 97% with 96%sensitivity and 100% specificity for thoracic abnormalities.Similarly, Yikilmaz and colleagues demonstrated MR with fast-imaging sequences at 1.5T to be comparable to CRs forpediatric pneumonia. Neither study specifically evaluated CLA,although Gorkem and colleagues’ study did have 1 case of abronchogenic cyst.13 These findings are promising and supportthe assumption that MR may be able to serve as a CT alter-native for CLA evaluation.

FIGURE 1. Coronal image through the thorax of a fetus dem-onstrates a triangular-shaped CPAM (X) within the left lower lobethat is hyperechoic to the adjacent normal lung (+) and heart/descending aorta (*).

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Postnatally, the respiratory system becomes air filled,resulting in marked trachea, bronchial, and lung hypointensityon all pulse sequences, providing little anatomic detail outsideof pathologic abnormalities. However, definition of aberrantvascularity remains exquisite, particularly after gadoliniumadministration. It should be noted that gadolinium should onlybe utilized if necessary in the early neonatal period, given therelative renal insufficiency of newborn kidneys.

In addition to standard descriptive anatomic informa-tion, MR can provide useful physiological data beyond whatis available by other modalities. Residual lung volumes oftenrepresent the predominant driver of morbidity and mortalityin patients with large CLAs.14 Phase contrast imaging cangive useful flow dynamics within some vascular CLAs.15

Lastly, MR is limited in the full evaluation of thepulmonary parenchyma given the low proton density of lungtissue and resultant weak MR signal. To compensate,hyperpolarized gases, for example, 3He and 129Xe, have beeninvestigated as methods to improve lung MR signal.16–18

Thus, both structural and functional information can beobtained with ventilation imaging. However, research inchildren has been largely confined to those with asthma andcystic fibrosis.18 As such, the utility of hyperpolarized gas forCLA evaluation has not yet been demonstrated.

SPECTRUM OF IMAGING FINDINGS

Branching Anomalies

Developmental Interruptive LesionsAgenesis, Hypoplasia, and Aplasia. Fetal lung under-

development is classified into 3 categories: lung agenesis,lung aplasia, and lung hypoplasia.2,3

Currently, the cause of pulmonary agenesis and apla-sia remains unknown. With pulmonary agenesis, there iscomplete absence of all normal pulmonary structuresaffecting either one or both hemithoraces. In pulmonaryaplasia, a rudimentary bronchus is present, whereas thelung parenchyma and pulmonary vasculature are absent.When affecting both hemithoraces, pulmonary agenesis/aplasia is uniformly fatal. However, patients with unilateralpulmonary agenesis/aplasia may remain asymptomatic intoadulthood.

In contrast, the pulmonary artery and bronchus arepresent but hypoplastic with a variable degree of lungparenchyma in pulmonary hypoplasia. Pulmonary hypo-plasia is divided into 2 subcategories. In primary pulmo-nary hypoplasia, there is no identifiable cause. Secondarypulmonary hypoplasia results from limited fetal pulmonarydevelopment produced by varied intrinsic and extrinsiccauses, such as congenital diaphragmatic hernia, oligohy-dramnios, thoracic dystrophies, and congenital pulmonarymasses.2,3

The imaging appearance of pulmonary agenesis,aplasia, and hypoplasia is dependent on the amount ofpulmonary structures present. On all imaging scans, theaffected hemithorax is asymmetrically small with hemi-diaphragm elevation and variable amounts of mediastinalshift. Hyperinflation of the contralateral lung may bepresent and can herniate across the central chest (Fig. 3).

Bronchial Atresia (BA). BA results from subsegmentalor segmental bronchial obstruction with normal formationof the airway distal to the obstruction. The exact cause ofthe obstruction remains elusive with 2 theories proposed.One theory holds that BA results from obliteration of theconnection between the primitive bronchial cells and the tipof the bronchial bud. A second theory postulates that BAresults from a focal ischemic insult causing focal bronchiallumen disconnection.3

Historically, BA was thought to be an isolated anomaly.This is no longer the case as multiple associated congenitalanomalies have recently been described. In a study by Ried-linger et al,19 BA was present in 50% of congenital lobaremphysema (CLH) cases, 70% of congenital pulmonary air-way malformations (CPAM), 82% of intralobar sequestra-tions, and 100% of extralobar sequestrations. The associationof BA with sequestrations and CPAMs has led to the phrase“bronchial atresia sequence” to encompass this maldevelop-ment spectrum.19 Generally, pediatric BA patients present withrecurrent infection or respiratory distress with severity relatedto the degree of parenchymal disease. With little or noparenchyma involvement, patients may remain asymptomatic.

Classically described on CR, BA appears as a round oroval opacity, most commonly in the apical or apicoposte-rior upper lobe segments, although it may occur in anysegment. These opacities represent impacted mucous distalto the atretic bronchus. With distal air trapping, a focalhyperlucency lung segment may be seen. If there is anassociated congenital mass, mucus impaction and airtrapping may be obscured. In this case, the CR appearancewill be that of the associated mass. If additional imaging isnecessary, CT is often the next modality utilized. Distal tothe atretic bronchus, mucous-filled bronchi will appear asdilated, tubular opacities. Hyperinflated lung will be seendistal to the impacted bronchi and is thought to result fromcollateral air drift through pores of Kohn and the pulmo-nary interstitium2,3,6,20,21 (Fig. 4). Current treatmentinvolves resection because of increased infection risk.

FIGURE 2. Sagittal T2 image through the fetus shows a trian-gular-shaped hyperintense mass (*) representing a CPAM, whichresides posterior to the heart within the left lower lobe.

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Foregut Duplication Cyst. On gestational day 26, lungdevelopment begins as a ventral diverticulum from theprimitive foregut. Foregut duplication cysts result fromdefective foregut budding and comprise a spectrum ofabnormalities including esophageal duplication and bron-chogenic, and neurenteric cysts. Differentiation is based onhistologic examination with bronchogenic cysts containingrespiratory epithelium and esophageal duplication cystsdemonstrating squamous epithelium and/or pseudos-tratified epithelium22 (Fig. 5A). Esophageal duplicationcysts may contain other ectopic gastrointestinal tract tissueincluding ectopic gastric mucosa with the associated risk forhemorrhage.23

Bronchogenic cysts occur in the paratracheal, hilar,and subcarinal regions in 65% to 90% of cases, mostcommonly in the subcarinal region6,24–26 (Fig. 5B). In 12%of cases, bronchogenic cysts occur intraparenchymally.27

Esophageal duplication cysts occur in a similar distributionand may be intimately associated with the esophagus. Iflocated in the middle mediastinum and associated with thefocal cleft in the adjacent vertebral body, a neurenteric cystmay be diagnosed.

Typically, small lesions are asymptomatic and inci-dentally detected. With large lesions, patients may becomesymptomatic, often presenting with respiratory symptoms,dysphagia, or chest pain. Cysts may become infected if incontinuity with the esophagus or tracheobronchial tree; thismanifestation occurs more often in older children and is lesscommon in infants and neonates.

On prenatal US, foregut duplication cysts appear asunilocular, cystic masses most commonly found in themiddle mediastinum.28 If a prenatal MR is performed, theyusually manifest as well-circumscribed, smooth masses withheterogenous T1 signal and T2 hyperintensity.4 If cysticfluid is hemorrhagic or significantly proteinaceous, dupli-cation cysts may be uniformly T1 hyperintense.

Yet, foregut duplication cysts are often first identifiedon CR, manifesting as round or oval, well-circumscribedmasses.2 Splaying of the main stem bronchi may be seen.Generally, CT is performed for further evaluation oncedetected on CR and these lesions share a similar CTappearance as smooth, well-defined, rounded or oval masseswith homogenous internal attenuation if uncomplicated(Fig. 5). Fifty percent of lesions will have CT attenuationvalues close to that of water.3,6 However, variable attenu-ation can occur depending on cystic fluid protein content.Postcontrast, uncomplicated foregut duplication cysts have

FIGURE 3. A, Frontal radiograph of the chest in a neonate showsunilateral agenesis of the left lung. The heart and mediastinalstructures are shifted into the left hemithorax. Note the umbilicalvenous catheter, which is deviated to the left of midline, butremains within the right atrium. B, Axial image from a contrast-enhanced CT of the thorax reveals absence of the left pulmonaryartery and pulmonary veins. M indicates main pulmonary artery;RP, right pulmonary artery.

FIGURE 4. Coronal reformatted image from a contrast-enhancedCT of the thorax shows hyperlucency within the apicoposteriorsegment of the left upper lobe, surrounding a tubular opacity(arrow) extending to the left superior hilum, findings represent-ing BA.



minimal or no wall or internal enhancement. With con-current or prior infection, foregut duplication cysts mayhave a thick or irregular wall with more robust enhance-ment. Air-fluid levels may also be seen.

If infected or symptomatic, thoracoscopic or opensurgical resection may be performed. Recent alternatives tosurgical resection have been proposed and include percu-taneous or transbronchial cyst aspiration.2

Ectopic or Supernumerary Bronchial LesionsTracheal Bronchus. First described in 1785 by Sandifort

as an aberrant bronchus originating from the trachea andsupplying the right upper lobe, the term tracheal bronchusnow refers to multiple bronchial anomalies whereby anaberrant bronchus arises from either the main bronchi or thetrachea and supplies the upper lobe territories.29 Over theyears, additional terms have been utilized. “True” tracheal

bronchi originate directly from the trachea, normally within2 cm from the carina. A displaced bronchus refers to theabsence of a normal upper lobe bronchus with the trachealbronchus supplying the entire ipsilateral upper lobe. A “pigbronchus” refers to when the right upper lobe bronchus isdisplaced onto the trachea. The bronchus is termed super-numerary when it supplies the ipsilateral upper lobe inadditional to a normally bifurcating or trifurcating upperlobe bronchus.30 Prevalence is 0.1% to 2% on the right and0.3% to 1% on the left.29,31 A displaced tracheal bronchus ismore common than a supernumerary type.32

Affected children are usually asymptomatic. However,tracheal bronchi can be associated with recurrent upperlobe infection, bronchiectasis, or persistent upper lobeatelectasis. Tracheal bronchi may occur with other con-genital anomalies including cardiac anomalies, trachealstenosis, and in Down syndrome.30

Although not often apparent on CR, tracheal bronchimay appear as a tubular lucency arising from either the tra-chea or main stem bronchi and tracking into the ipsilateralupper lobe. An ipsilateral upper lobe opacity can be seen withsuperimposed infection or atelectasis. Nevertheless, trachealbronchi are almost always first diagnosed on cross-sectionalimaging. On CT, tracheal bronchi appear as a well-definedbronchus arising from the trachea or main stem bronchi andextending into the ipsilateral upper lobe (Fig. 6). Super-numerary or displaced subtyping is readily apparent byevaluating for a normal branching pattern of the mainbronchi. 3D reconstructions exquisitely demonstrate theaberrant bronchial anatomy, but their definitive usefulnessfor treatment planning has yet to be demonstrated. MRimaging occasionally may demonstrate the presence of atracheal bronchus as a hypointense tubular branch.

As these anomalies are usually asymptomatic, noparticular treatment is normally needed. However, itspresence is important to communicate in patients under-going intubation because of the risk of occluding thebronchus. With recurrent infection, surgical resection ofboth the bronchus and the lobe it supplies may benecessary.33

Accessory Cardiac Bronchus. An accessory cardiacbronchus is a supernumerary bronchus originating from themain bronchi or bronchus intermedius and coursing in aninferior direction toward the pericardium. Most endblindly. Overall frequency in the population is approx-imately 0.08%.29 Accessory cardiac bronchi are oftenasymptomatic. In older children, they may serve as a sourceof recurrent infection, and affected patients can presentwith cough and hemoptysis.29 Cases of aspergillomas andtumors within accessory cardiac bronchi have beenreported.29,34,35

The role of CR is limited. If infection or tumor ispresent, a focal soft tissue opacity may be demonstrated,most commonly in the subcarinal region. Still, cardiacbronchi are almost always first demonstrated on CT. Here,cardiac bronchi will appear as a focal accessory bronchusarising from the inferior aspect of the main stem bronchi orthe medial wall of the bronchus intermedius. Theseanomalies then course inferiorly to the adjacent pericar-dium where they abruptly end in a blind pouch. Infection ortumor appears as a focal opacity at the tip or surroundingthe cardiac bronchus.

No treatment is necessary for uncomplicated accessorycardiac bronchi. If recurrent infection develops or tumor ispresent, a thoracotomy with surgical resection is warranted.

FIGURE 5. A, Medium-power pictomicrograph of a section froma bronchial duplication cyst view showing pseudostratified col-umnar epithelium and glands. B, Coronal reformatted imagefrom a contrast-enhanced chest CT demonstrates a mediastinalmass (*) splaying the carina and resulting in obstruction of theleft main stem bronchus with air trapping (arrows) in the leftlower lobe.



Parenchymal Anomalies

Congenital Lobar Hyperinflation (CLH)CLH, also known as congenital lobar emphysema and

congenital lobar overinflation, results from intrinsic orextrinsic narrowing of the bronchial lumen and manifests asoverinflation of 1 or multiple pulmonary lobes.2,3 Absenceor weakness of bronchial cartilage represents intrinsiccauses of bronchial narrowing.2 Extrinsic etiologies includeenlarged or aberrant vessels and mediastinal masses.

There are 2 classifications of CLH predicated onalveolar number. Hypoalveolar CLH has fewer thanexpected alveoli with alveolar overdistension. In poly-alveolar CLH, the number of alveoli is increased 3- to 5-fold in the affected lung segment with each individualalveolus normally inflated (Fig. 7A). Thus, the affectedlobe(s) are overinflated because of the increased number ofnormally inflated alveoli.2,3 Presentation often depends ontype, with hypoalveolar CLH presenting earlier in life.Respiratory distress is what typically brings patients toclinical attention, with severity dependent on the amount ofhyperinflation and associated compression of mediastinalstructures and adjacent lung.2,6 CLH is often detectedduring the neonatal period and has a distinct lobe predi-lection. The most common site is the left upper lobe,with the right middle lobe being the next most commonfollowed by the right upper lobe (Fig. 7B). Lower lobeinvolvement is uncommon. Rarely, CLH may be bilateralor multifocal.36

On fetal US, CLH manifests as a hyperechoic,homogenous mass with variable associated compression ofthe adjacent normal lung and mediastinal structures. Onfetal MR imaging, CLH presents as a homogenous, T2-hyperintense mass.4 With CR, CLH demonstrates a classictemporal progression in the early neonatal period. Early on,CR will show a focal mass-like opacity resulting fromretained fetal fluid. As fetal fluid is cleared, there is pro-gressive hyperlucency of the affected lobe(s). The affectedlobe(s) may become increasingly overdistended withincreasing compression of the adjacent lung and media-stinum. If detected past the neonatal period, CLH may be

confused with CPAM. Here, CT can be useful for furthercharacterization and differentiation. In large CLH lesions,the affected lobe(s) will be hyperinflated with displacementof the pulmonary vessels, compression of the adjacent lung,and contralateral mediastinal shift. Ipsilateral hemi-diaphragm compression and rib interspace splaying may beseen.6

CLH is treated surgically, with timing dependent onlesion size and the degree of respiratory compromise.6,37–40

Care must be taken during operative ventilation to avoidpreferential aeration of the affected lobe with associatedprogressive hyperinflation and respiratory/cardiovascularcollapse from tension physiology. With successful surgicalresection, patients have an excellent prognosis.39

CPAMCPAMs are a heterogenous group of cystic and non-

cystic anomalies and are the most common CLA,

FIGURE 6. Anterior view from a volume-rendered 3D CT imageof the lungs and airway demonstrates the entire course ofa tracheal bronchus (arrow) and its relationship to the distaltrachea.

FIGURE 7. A, Pictomicrograph at low-power magnificationreveals an increased number of alveoli, which are normallyinflated and without features of maldevelopment consistent withpolyalveolar CLH. B, Coronal reformatted CT image demon-strates hyperlucency of the left upper lobe in this patient withCLH.



representing about 30% to 40% of cases.41–44 CPAMs arethought to result from early airway maldevelopment fromintrauterine airway obstruction,2,4 supported by histologicand pathologic changes of exuberant primary bronchiolarovergrowth in communication with an abnormal bronchialtree lacking cartilage.2,24,32,37,45–47 Arterial supply normallyarises from the pulmonary artery with pulmonary venousdrainage. Patients present early in life with respiratorydistress. If presenting in later life, they often manifest asrecurrent infection involving the same segment of the lung.However, a substantial portion of CPAMs may remainasymptomatic throughout life and are only incidentallydetected.

CPAM classification was first proposed by Stockeret al in 197746 and was recently updated by Stocker,47

expanding from 3 to 5 types. With this expansion, the oldnomenclature of cystic adenomatoid malformations wasreplaced by CPAM. This term is more accurate given thatonly 3 of 5 types are cystic and only 1 type has adenomatoidchanges. The revised Stocker classification includes 5 types(0 to 4), with classification predicated on histologic sim-ilarities to the developing bronchial tree and airspace aswell as cyst size.47 Type 0 CPAMs have severe acinar

dysgenesis affecting all lung lobes and are uniformly fatal.Solitary or multiple macrocysts (>2 cm) characterize type 1CPAMs and are of bronchial or bronchiolar origin (Fig. 8).Type 2 CPAMs have single or multiple cysts of bronchiolarorigin measuring between 0.5 and 2 cm (Fig. 9). Type 3CPAMs have multiple microcysts measuring r0.5 cm andare predominately solid. This type is the only adenomatoidCPAM type and has a bronchiolar-alveolar duct origin.Type 4 CPAMs have a distal acinar origin and are char-acterized by large air-filled cysts. Type 4 CPAMs areindistinguishable by imaging from type 1 pleuropulmonaryblastoma.2,4,47

CPAMs are often first identified on prenatal US. OnUS, the overall mass size and associated compressive effectson the adjacent normal lung and mediastinal structuresmay be assessed. In some cases, CPAMs may be sub-categorized prenatally, adding important prognostic value.Types 1 and 2 (macrocystic) CPAMs appear on prenatalUS as echogenic masses with variable-sized cysts.4 Type 3CPAMs are indistinguishable on prenatal US from othersolid CLAs, appearing as a homogenous echogenic mass.Occasionally, associated anomalous vascularity may be

FIGURE 8. A, Coronal reformatted image from a contrast-enhanced CT of the thorax in a patient with a type 1 CPAMshows a large air-filled cyst within the right upper lobe. B, Grosssurgical specimen showing a large cyst with a trabeculated wallin a type 1 CPAM.

FIGURE 9. A, Axial image from a contrast-enhanced CT of thethorax in a different patient with a type 2 CPAM reveals a mul-ticystic mass in the right lower lobe. Note that none of the air-filled cysts measure >2 cm in diameter. B, Low-power magnifi-cation view of microcystic, dilated bronchiole-like structures in atype 2 CPAM.



seen. In such cases, a hybrid lesion is diagnosed (furtherdiscussed below).

CRs are often utilized in the postnatal period, andimaging manifestations are dependent on the underlyingtype. The single exception to this principle is type 0 CPAMs,which generally receive no postnatal imaging given therapidly deteriorating clinical course. On CR, type 1 CPAMsappear as a mixed solid and cystic lung mass with at least 1cyst measuring >2cm. If a single large/dominant cyst ispresent, they may be difficult to distinguish from CLH.Similarly, type 2 CPAMs are mixed cystic lung masses withcysts measuring 0.5 and 2 cm.4,47 Alternatively, type 2CPAMS may manifest as a persistent area of consolidationwith cysts only demonstrable on cross-sectional imaging.2

Much like their prenatal sonographic appearance, type 3CPAMs appear on CR as solid-appearing focal opacitiesindistinguishable from other solid CLAs. Type 4 CPAMsare indistinguishable from type 1 pleuropulmonary blasto-mas, appearing as a large cystic lesion.

After initial chest radiographs, CT or MR imaging isoften utilized for further characterization and treatmentplanning. With these modalities, the imaging appearanceclosely correlates with that of their CR appearance withcyst presence and size determining type classification(Fig. 8A). These cysts may be completely air filled or con-tain air-fluid levels.6 On MR, if the cysts are fluid filled,typically the fluid is hyperintense on T2. Conversely, if thecysts are air filled, they usually appear diffusely hypointenseon all pulse sequences. Type 3 CPAMs are composed ofinnumerable microcysts, which are in general notindividually discernible on CT or MR. Thus, type 3CPAMs almost always appear on CT and MR as a focalsolid lesion with diffuse homogenously increased T2 signalon MR.4

Treatment for symptomatic patients is operative, which isnow often performed via thoracoscopy with either a lobec-tomy or segmentectomy performed. Treatment for asympto-matic patients remains controversial. Most believe that electiveresection is prudent given the associated risks of hemorrhage,recurrent infection, and potential risk for malignancy.6

Vascular Anomalies

Anomalies of the Pulmonary ArteryInterruption (Absence) of a Main Pulmonary Artery.

The primitive sixth aortic arch gives rise to the proximalaspect of the main pulmonary artery. Failure of the for-mation of the sixth aortic arch results in proximal inter-ruption of the pulmonary artery. Given their differingembryological origin, the hilar and distal pulmonaryarteries form normally.6,48–51 Vascular supply to theaffected lung results from collateralization of flow throughbronchial and intercostal arteries with enlargement of thecontralateral pulmonary vessels. However, overall flow tothe affected lung is diminished, resulting in ipsilateralpulmonary hypoplasia. Venous drainage of the affected sideis usually normal.6 Patients typically present withhemoptysis from bronchial arterial enlargement, pulmo-nary hypertension, or recurrent infection, although patientsmay remain asymptomatic.50,51

Proximal interruption of the pulmonary artery maymanifest in a similar manner on CR as mild to moderatepulmonary hypoplasia with small lung size, volume loss,and mediastinal shift. The intraparenchymal vascularity isdiminished, and the ipsilateral hilum may appear small or

absent. With collateralized arterial supply, there may alsobe increased peripheral reticular vascular markings. On CT,the focal absence of the proximal pulmonary artery isshown to best advantage with termination of the pulmo-nary artery usually within 1 cm of its origin from the mainpulmonary artery. Recently, MDCT angiography with 3Dreconstructions has been shown to have particular utility indepicting not only the focal discontinuity of the pulmonaryartery but also the extent of arterial collateralization,contralateral pulmonary artery enlargement, and associatedcentral airway anomalies.10

Early treatment is key, as it may improve affected lungand pulmonary arterial growth. Surgical intervention con-sists of grafting or direct anastomosis of the main and hilarpulmonary artery segments. In older patients presentingwith recurrent hemoptysis or pulmonary hypertension,embolization of collateral vessels may be warranted.2,6

Anomalous Origin of the Left Pulmonary Artery Fromthe Right. If the left sixth aortic arch is completely obli-terated during development, the left pulmonary artery mayarise anomalously from the posterior right pulmonaryartery. This rare congenital anomaly is commonly referredto as a pulmonary sling, with the term sling deriving fromthe left pulmonary artery having a looping appearancearound the trachea as it passes between the trachea andesophagus from right to left. Patients generally present atan early age with upper and lower respiratory symptomsincluding episodic apnea, stridor, and respiratorydistress.2,3

Anomalous origin of the left pulmonary artery fromthe right occurs in 2 varieties. Type 1 is associated with anormally positioned carina at the T4 to T5 vertebral level,with characteristic compression of the posterior trachealwall, anterior esophageal wall, and the right main stembronchus. In type 2 pulmonary artery slings, the trachea iselongated with inferior carinal displacement, generally tothe T6 level. The carina takes on a T-shaped morphologywhereby the main bronchi arise perpendicularly from thecarina giving them a horizontal course. In 50% of cases,there is diffuse tracheal stenosis with complete cartilaginousrings. Fifty percent of patients with a type 2 pulmonarysling will have congenital heart defects.52

Pulmonary sling imaging manifestations are depend-ent on type and associated anomalies. Classically, on con-trast esophagram there is an external impression on theposterior aspect of the trachea and the anterior aspect ofthe esophagus, the only vascular anomaly to cause thisappearance. A complete vascular ring is formed when aligamentum arteriosum is present, encircling and com-pressing the trachea while sparing the esophagus.

On CR, the right lung may be hyperinflated owing toright main stem bronchus compression. On the lateralradiograph, the posterior tracheal wall may be compressedby a soft tissue opacity interposed between the trachea andbronchus, with anterior tracheal displacement. MDCT with3D reconstructions have been shown of value in the eval-uation of pulmonary slings and is the current imagingmodality of choice6,10 (Fig. 10). MDCT demonstrates theanomalous origin and course of the left pulmonary artery.3D reconstructions of the airway demonstrate the config-uration and extent of tracheal stenosis. Paired inspiratoryand expiratory views are of great value in demonstratingassociated tracheomalacia. In type 1, both axial and sagittalimages can demonstrate the anterior esophageal impressionand compression of the posterior tracheal wall. With



intravenous contrast, the looping anomalous course of theleft pulmonary artery can be seen. Associated right lunghyperinflation is best depicted with expiratory images.6 CTfeatures of a type 2 pulmonary sling include a T-shapedcarina with caudal displacement of the carina to the T6level. Long-segment tracheal stenosis may be demonstratedand is seen to best advantage on coronal reformations and3D reconstructions (Fig. 10B). When assessing type 2pulmonary slings, it is prudent to image the entire course ofthe trachea, as the stenosis can be diffuse. Demonstratingthe extent of stenosis is helpful for planning surgicalintervention.6

Although less often utilized, MR imaging can readilydemonstrate the left pulmonary artery’s anomalous origin

and course. Right lung hyperinflation can be detected byasymmetric hemithorax volumes. Tracheal narrowing canalso be depicted, although generally with less definitionthan that seen on MDCT.

Surgical division and reimplantation of the left pulmo-nary artery is the treatment of choice. With long-segmenttracheal stenosis, tracheoplasty may be necessary. Alter-natively, stenosis resection with end-to-end anastomosis maybe utilized for short-segment tracheal stenosis.53,54

Anomalies of the Pulmonary VeinPulmonary Vein Stenosis (PVS). Etiologies for PVS

include both acquired and congenital causes. Congenitallesions can be life threatening and are rarer, resulting fromuncontrolled fibroblast growth with thickening and nar-rowing of the pulmonary vein.6 Pediatric patients oftenpresent with symptoms of pulmonary edema such asshortness of breath, cyanosis, and fatigue.

Correlating with patient symptomatology, CR demon-strates signs of reduced pulmonary venous drainage,pulmonary venous hypertension, and pulmonary edema.Recently, Mayhew et al55 evaluated CR findings in 41 infantswith known PVS. The most common CR findings includedincreased interstitial opacity (100%), reticular opacity (85%),and ground-glass opacity (71%). Although these are non-specific signs of pulmonary edema, given the population ageand the very high percentage of these findings, the authorsconcluded that PVS should be considered particularly whenthese findings are heterogenous or unilateral.55

Although PVS may be depicted on MR, CT is oftenutilized for cross-sectional imaging as it better demonstratesassociated lung parenchymal changes. The affectedpulmonary venous segment is usually at or near its junctionwith the left atrium (Fig. 11). With disease progression,pulmonary vein thickening and narrowing may extend intoadjacent distal intraparenchymal pulmonary vein segments.Pulmonary parenchymal changes follow that of unilateralpulmonary edema. Recently, the utilization of 3D recon-structions in the pediatric population has been shown tosignificantly increase diagnostic accuracy, diagnostic value,confidence level, and intraobserver agreement.56

Due to the potential life-threatening consequences ofPVS, accurate and prompt diagnosis is paramount. Treatmentstrategies depend on disease extent. Focal or short-segmentPVS is treated with percutaneous balloon dilatation andstenting. In long-segment stenosis, lung transplantation maybe required.

Partial Anomalous Pulmonary Venous Return (PAPVR).PAPVR occurs when 1 or more pulmonary veins retain anembryologic connection to the primitive splanchnic system ofcardinal veins.57 The anomalous drainage pattern is varied,and these anomalous veins may drain into the vena cavae, thecoronary sinus, azygous vein, a persistent left vertical vein, ordirectly into the right atrium. A concurrent sinus venosusdefect may be present, particularly in patients with right upperlobe PAPVR.52 PAPVR results in a right to left shunt. Ifhemodynamically significant, patients will present with symp-toms of pulmonary overcirculation and pulmonaryhypertension.

Imaging findings of PAPVR are dependent on locationand number of the anomalous pulmonary vein/veins, wherethe veins drain, and findings of pulmonary overcirculation.In general, CRs are limited for the evaluation of PAPVR(with the exception of scimitar syndrome—discussed later).In the presence of a hemodynamically significant shunt,

FIGURE 10. A, Axial image from a contrast-enhanced CT of thethorax reveals the aberrant left pulmonary artery (arrow) arisingfrom the right pulmonary artery in a patient with a pulmonaryartery sling. The pulmonary artery courses posterior to the tra-chea and anterior to the esophagus to reach the left lung. B,Anterior view from a volume-rendered 3D image of the tracheaand proximal bronchi shows diffuse narrowing of the intra-thoracic trachea (arrow) due to complete cartilaginous rings anda “T-shaped” configuration of the carina characteristic of a type 2pulmonary artery sling.



CRs may demonstrate pulmonary arterial and right heartenlargement.

Both CT and MR can clearly demonstrate the numberand course of the anomalous pulmonary veins (Fig. 12). Themost common PAPVR involves a vertically oriented anom-alous left upper lobe pulmonary vein, which courses lateral tothe aortic arch with drainage into the left innominate vein.This type is also the most common to not have an associatedcongenital heart lesion.52,58 CT and MR can also demon-strate the associated sinus venosus defect, appearing as afocal defect in the posterior-superior atrial septum. On CT,intermixing of contrast-enhanced and noncontrasted bloodacross this defect may be demonstrated. On MR, a jet flowvoid may be demonstrated to pass through the defect.

PAPVR is usually associated with an excellent prog-nosis. Surgical correction with patch placement is per-formed if a sinus venosus defect is present. If the anomalousdrainage is to the superior vena cava, the patch can beextended to separate the pulmonary from systemicdrainage.30

Combined Anomaly of the Pulmonary Artery andPulmonary Vein

Pulmonary Arteriovenous Malformation (AVM).AVMs are a consequence of a segmental maldevelopmentof pulmonary capillaries resulting in direct communicationof a pulmonary arterial branch with its associated/adjacentpulmonary vein. An alternative and more accurate term forpulmonary AVMs is pulmonary arteriovenous fistulae.Nevertheless, common convention refers to these lesions aspulmonary AVMs.

Pulmonary AVMs are most often congenital with asmall population being acquired, typically in patients withchronic liver disease, those who have had prior surgery forcongenital heart disease, and in patients with prior atypicalinfection, for example, tuberculosis.3,6,59–63 CongenitalAVMs are classically associated with Osler-Weber-Rendu,also known as hereditary hemorrhagic telangiectasis(HHT), an autosomal dominant disorder.

Patients with HHT often come to clinical attention dueto symptoms or for screening in the setting of an HHTfamily history. The classic symptom triad includes epistaxis,family history, and telangiectasias, particularly nasal. Strokeor cerebral abscess may occur from right to left shunting.Thirty-five percent of HHT patients have 1 or morepulmonary AVMs3 and may also have AVMs in otherorgans such as the liver, pancreas, and gastrointestinal tract.

Pulmonary AVMs manifest on CR as nodular orlobulated well-circumscribed soft tissue opacities, with 50%to 70% occurring in the lower lobes.6 Solitary or multipleAVMs may be present. Occasionally, a tubular or curvi-linear opacity may be seen to extend from the lesion with acourse directed toward the ipsilateral hilum, representingthe draining vein, the feeding artery, or both. Generally, theintraparenchymal nature of these lesions is apparent,

FIGURE 11. A, Axial image from a contrast-enhanced CT of thethorax in a patient with PVS demonstrates narrowing (arrows)near and at the level of pulmonary vein insertion involving veinsfrom both lungs. B, Posterior view from volume-rendered 3D CTimage from the same patient shows narrowing (arrow) of the leftpulmonary vein.

FIGURE 12. Coronal image from contrast-enhanced MRangiography demonstrates drainage of the upper and middlelobe pulmonary veins (arrow) into the superior vena cava justabove the level of the right atrium, findings consistent withpartial anomalous pulmonary venous return.



although pulmonary AVMs may project over the media-stinum on both frontal and lateral projections, makingexact localization difficult.3

After CR, MDCT is often performed and representsthe modality of choice for assessing number, size, andlocation as well as the associated vascular supply. Contrast-enhanced examinations are preferable. However, AVMsmay be seen on noncontrast CT obtained for alternativereasons and manifest as a focal, serpiginous or lobulated,intraparenchymal soft tissue nodule or mass. On post-contrast imaging, pulmonary AVMs robustly enhance, andthe feeding and draining vascular pattern becomes readilyapparent. In lesions with complex angioarchitecture, 2D-MPR and 3D reconstructions may be valuable in fullyelucidating the vascular supply (Fig. 13).

The quantity of right to left shunting throughpulmonary AVMs is the predominant driver of bothsymptoms and need for intervention. Generally, treatmentis offered when feeding arteries reach a diameter of 3mm orgreater, even if asymptomatic. Treatment options includeballoon occlusion, coil embolization, and surgical excision.

Combined Lung and Vascular Anomalies

Hypogenetic Lung (Scimitar) SyndromeHypogenetic lung syndrome, classically known as sci-

mitar syndrome, consists of right-sided PAPVR, right lunghypoplasia, heart dextroposition, and anomalous right lungsystemic arterial supply.4,6,24,32,64 The anomalous pulmo-nary vein may drain into the portal venous system, thehepatic venous system, or, most commonly, the inferiorvena cava. Other congenital anomalies are common andoccur in up to 25% of cases.2 Clinical presentation is

dependent on patient age. Older children often present withrecurrent infection in the right base. Young infants oftenpresent with symptoms of right to left shunting andpulmonary overcirculation from the anomalous pulmonaryvenous drainage. Some patients may remain asymptomatic.

Scimitar syndrome is largely detected postnatally,although there are a few reports within the literaturedescribing prenatal detection.65–67 CR often is the firstpostnatal imaging study. Unlike many of the afore-mentioned anomalies, scimitar syndrome is rather unique inthat its definitive diagnosis can be made by the radiographalone. The anomalous pulmonary vein appears as a curvi-linear, tubular soft tissue opacity coursing in a verticalorientation in the lower right hemithorax. The right hemi-thorax is small in size, and the right lung is hypoplastic andhyperlucent (Fig. 14).

Despite the ability of CRs to make the definitivediagnosis, most patients undergo cross-sectional imaging,that is, CT or MR. CT and MR are beneficial in demon-strating the anomalous pulmonary vein course, caliber, anddrainage pattern. The scimitar vein most commonly drainsinto the inferior vena cava and less commonly into thehepatic veins, portal veins, right atrium, superior vena cava,and the azygous vein.3,6,32,42,68 With angiographic techni-que, the anomalous arterial supply may also be demon-strated. 3D reformations are helpful in demonstrating boththe venous and arterial anomalies in a single image.6 Otherassociated nonvascular anomalies are readily demonstratedon CT including hypoplasia of the right lung with alteredlobulation and bronchial branching anomalies.2,6,69 Post-operatively, CT is helpful in evaluating reimplantationcomplications, for example, thrombosis and stenosis.

Treatment is largely reserved for symptomaticpatients, especially with a left to right shunt ratio >2:1. Theanomalous systemic arterial supply is often embolized withsurgical reimplantation of the anomalous pulmonary veinto the left atrium.2,6

Pulmonary SequestrationPulmonary sequestrations represent the second most

common congenital pulmonary anomaly.4 It is composedof dysplastic pulmonary tissue, contains no normal con-nection to the tracheobronchial tree, and receives a systemicvascular supply.2–4,6,32,42,48,70–72 Pulmonary sequestrationsare traditionally divided into 2 categories, that is, intralobarversus extralobar, on the basis of its venous drainage pat-tern and pleural investment. Intralobar sequestrationscomprise 75% of sequestrations. They do not have theirown pleural investment but rather share pleura with theadjacent normal lung. Generally, intralobar sequestrationsdrain through the ipsilateral pulmonary venous system.4 Itremains controversial whether or not these represent truecongenital anomalies in all cases, with some authors argu-ing that they are acquired as a result of recurrent localizedinfection, resultant bronchial obstruction, and eventualparasitization of the adjacent systemic vascular supply.However, with prenatal imaging advances, evidence sup-ports that at least a subcategory is congenital as there hasbeen increased detection of intralobar sequestrations in thefetal lungs. In contrast, extralobar sequestrations are gen-erally considered to be a congenital anomaly and accountfor 25% of sequestrations.2,3,6,32,48,70,72 Extralobar seques-trations drain through the systemic venous system andcontain their own pleural investment. Regardless of type,pulmonary sequestrations receive a systemic arterial supply

FIGURE 13. Coronal reformatted maximum intensity projectionCT image in an HHT patient reveals a right lower lobe pulmonaryAVM (arrow) with its associated feeding pulmonary artery (a) anddraining pulmonary vein (v).



most commonly directly from the thoracic or abdominalaorta with less common supply from the celiac, splenic,intercostal, subclavian, and coronary arteries.4,48

The presentation depends on the sequestration type.Extralobar sequestrations most often present in the neo-natal period or in early infancy as a focal mass on imaging.Intralobar sequestrations present later in childhood as afocus of recurrent infection.2,6,32,48,70,72

Like most congenital pulmonary anomalies, but partic-ularly with pulmonary sequestrations, imaging plays a keyrole in diagnosis and surgical planning. On prenatal US,sequestrations appear as a hyperechoic homogenous lesion,most commonly in the lower left hemithorax.4 Doppler maydemonstrate systemic arterial supply distinguishing seques-trations from other CLAs. Sequestrations appear on prenatalMR as a homogenous T2-hyperintense mass. Althoughgadolinium is often not utilized, the arterial supply may beseen as a serpiginous, tubular signal void arising from theaorta.4,42

After the prenatal period, the imaging appearance ofsequestrations is more variable and depends on type, con-current or prior infection, and other anomalies. US has alimited role postnatally. However, it does have value and maybe utilized to demonstrate the aberrant arterial supply to aprenatally detected mass and confirming the diagnosis.Depending on institutional and surgeon preferences, additionalimaging may not be obtained. However, a large majority ofpatients have a postnatal CR, often followed by CT.

Pulmonary sequestrations appear as a focal opacity ormass in the lower lobe in 98% of CRs.6,32 Occasionally, theaberrant systemic artery may be demonstrable.24 Withrecurrent infection, intralesional necrosis may develop, anda more cystic appearance with or without air-fluid levelsmay be seen.2,6

After the initial CR, MDCT with 3D reconstructionsis generally utilized for both diagnosis confirmation andpresurgical planning (Fig. 15). The mass itself can have avariable appearance ranging from a complex cavitary masswith intracystic air-fluid levels to a heterogenouslyenhancing solid lesion. In 50% of cases, sequestrations canbe categorized into intralobar and extralobar on the basisof the venous drainage pattern.73,74 Extralobar sequestra-tions most commonly drain into the azygous system andless commonly through the portal system, subclavian veins,and internal mammary veins.6,70,73 Intralobar sequestra-tions typically drain through the inferior pulmonary vein.6

A recent study consisting of 46 pediatric patients showedthat axial CT images allow accurate diagnosis of the types,location, associated mass effect, and anomalous arteries ofCLAs. However, supplemental MPR and 3D MDCTimages add additional diagnostic value.10

A variant of sequestration known as a hybrid lesion isworth noting. Hybrid lesions represent a midpoint on aspectrum between CPAMs and pulmonary sequestrations.On CT, hybrid lesions show characteristics of a CPAMwhile having an anomalous systemic arterial supply.

MR and MR angiography provide nonradiationalternatives for the evaluation of pulmonary sequestrations.However, they are less often utilized given the limited def-inition of pulmonary parenchyma. Depending on the his-tory of infection, sequestrations appear on postnatal MR assolid lesions with both T1 and T2 hyperintensity, which isconsidered to result from internal airway mucus impac-tion.75–77 MR angiography images with or without the useof gadolinium have been shown to be effective in thedepiction of the aberrant arterial supply.3,75,78

Management is predominantly surgical given the riskfor recurrent infection and the small risk for associated

FIGURE 14. A, Frontal chest radiograph demonstrating a largeanomalous pulmonary vein (S). B, Coronal T2-weighted imageshows the anomalous pulmonary vein (S) draining into thejunction of the inferior vena cava (IVC) and right atrium (RA).



malignancy.2,30 Recently, embolization of the anomalousarterial supply has been suggested as an alternative tosurgery with a reported high rate of success.3,79,80

FUTURE DIRECTIONSAlthough much knowledge has been gained over the

last several decades regarding CLAs, there are still areasthat need further elucidation. Precise etiologies remainelusive for a large portion of these lesions. Further research,particularly in molecular biology and genetics, may helpshed light into why and when these abnormalities occur.Continued research and utilization of advanced imagingtechniques with particular emphasis on nonradiationalternatives may be helpful in future imaging. One partic-ularly fruitful area is in the advancement of chest MRimaging in which imaging times are progressively decreas-ing with ever-increasing spatial resolution.12 However, MRremains deficient in lung parenchymal detail when com-pared with CT, although this particular drawback is cur-rently the subject of research, with recent studies supportingfast-imaging MR sequences as comparable to CT forthoracic abnormalities. Lastly, the establishment of a con-sensus between our obstetric, pediatric, and surgical col-leagues in terms of optimal management for each lesioncould be helpful in standardizing practice and ultimatelyimproving patient outcomes.

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Kathy.Felix

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developmental lung malformations in children

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