John H. M. Austin, MD #{149}Nestor L. Muller, MD, PhD #{149}Paul J. Friedman, MD #{149}David M. Hansell, MBDavid P. Naidich, MD #{149}Martine Remy-Jardin, MD #{149}W. Richard Webb, MD #{149}Elias A. Zerhouni, MD

Glossary ofTerms for CT ofthe Lungs:Recommendations ofthe NomenclatureCommittee ofthe Fleischner Society’

I From the Department of Radiology, Colum-bia-Presbytenian Medical Center, 622 W 168th

St. New York, NY 10032-3784 (J.H.M.A.); De-partment of Radiology, University of British Co-lumbia and Vancouver Hospital and Health Sd-ences Centre, Canada (N.L.M.); Department ofRadiology, University of California San Diego,School of Medicine (P.J.F.); Department of Ra-diology, Royal Brompton National Heart andLung Hospital, London, England (D.M.H.); De-pantment of Radiology, New York UniversityMedical Center, NY (D.P.N.); Department of Ra-diology, H#{244}pita!Calmette, Lille, France (M.R.J.);Department of Radiology, University of Califor-nia San Francisco, School of Medicine (W.R.W.);

Department of Radiology, The Johns HopkinsUniversity School of Medicine, Baltimore, Md(E.AZ.). Received November 10, 1995; revisionrequested February 12, 1996; revision receivedMarch 18; accepted April 26. Address reprintrequests toJ.H.M.A.

C RSNA, 1996

327

Thoracic Radiology

I N 1984, the Nomenclature Commit-tee of the Fleischner Society pre-

sented the “Glossary of Terms forThoracic Radiology” (1). That glossarycovers mainly the terms used in theinterpretation of chest radiographic

examinations.In 1991, Drs Webb, Muller, and

Naidich offered an introductory glos-

sary of the vocabulary of thin-sectioncomputed tomography (CT) in theirbook, High-Resolution CT of the Lung

(2), and updated that glossary in 1993(3). The present committee, by using

those contributions as a base, nowoffers a considerably expanded glos-sary. Our intent is to list, define, andprovide references for the main termsused in chest CT that are specific tothe lungs. “HRCT” is used to indicatehigh-resolution computed tomogra-phy (2-4).

Use of words is inherently contro-

versial. We are pleased to invite read-ers to offer improvements to our defi-nitions.

Index terms: Computed tomography ‘ Lung,

CT

Radiology 1996; 200:327-331

air crescent

GLOSSARY

Air in a crescentic shape in a noduleor mass, in which the air separates theouter wall of the lesion from an innersequestrum, which most commonly isa fungus ball of Aspergillus species (5-7).

air trapping

1 . Pathophysiology.-The retentionof excess gas (“air”) in all or part ofthe lung, especia!ly during expiration,either as a result of complete or par-tial airway obstruction or as a result oflocal abnormalities in pulmonary com-pliance. Although not in common us-age, the term “gas trapping” is moreaccurate.

2. CT.-Decreased attenuation ofpulmonary parenchyma, especially

manifest as less than normal increasein attenuation during expiration (8-10). To be differentiated from the de-creased attenuation of hypoperfusionsecondary to locally increased pulmo-nary arterial resistance.

architectural distortion

A manifestation of lung disease inwhich bronchi, pulmonary vessels, afissure or fissures, or septa of second-ary pulmonary lobules are abnor-mally displaced (11-15).

band

See “parenchymal band.”

beaded septum sign

Irregular septa! thickening thatsuggests the appearance of a row ofbeads; usually a sign of lymphangiticcarcinomatosis (16), but may also oc-cur rarely in sarcoidosis (12,17). Be-cause the thickening usually is moreirregular than beaded, the term “ir-regular septal thickening” generally ispreferred.

bronchiectasis

1 . Pathology.-Irreversible dilata-tion of a bronchus or bronchi, oftenwith thickening of the bronchial wall(18,19). When mild, the dilatation iscylindric (ie, normal bronchial taper-ing is absent). When more severe, thedilatation is saccular, and irregularconstrictions may be present. Whenvery severe, the bronchi may be mark-edly dilated, especially distally (10,18,20).See also “traction bronchiectasis.”

2. CT.-Bronchial dilatation, oftenwith thickening of the wall (19-22).

bronchiolectasis

1 . Pathology.- Dilatation of a bron-

chiole or bronchioles, often with thick-ening of the bronchiolar wall (23).

2. CT.- Bronchiolar dilatation(13,14,23). See also “traction bron-chiolectasis.”

bulla

1. Pathology.-A sharply demar-cated, dilated air space that measures1 cm or more in diameter and pos-sesses a thin epithelialized wall, whichis usually no greater than 1 mm inthickness. See also “bullous emphy-sema,” “emphysema,” and “parasep-tal emphysema.”

2. CT.- A round, focal air space, 1cm or more in diameter, demarcatedby a thin wall; usually multiple or as-sociated with other signs of pulmo-nary emphysema.

bullous emphysema

Emphysema characterized by thepresence of bullae. See “emphysema.”

centriacinar emphysema

See “centrilobular emphysema.”

centrilobular

Referring to the region of the bron-chioloartenolar core of a secondary

328 #{149}Radiology August 1996

pulmonary lobule. See “centrilobularstructures.”

centrilobular emphysema

I . Pathology.-Emphysema that ischaracterized by destroyed centrilob-ular alveolar septa and enlargementof respiratory bronchioles (24-26).Usually in the upper lung zones ofcigarette smokers.

2. CT.-Centrilobular decreasedattenuation, usually without visiblewalls, of nonuniform distribution, andpredominantly located in upper lungzones (25,26). Synonym: centriacinaremphysema.

centrilobular structures

1. Anatomy.-The central tubularstructures in a secondary pulmonary

lobule (ie, the centrilobular artery andbronchiole) (27,28).

2. CT.-The pulmonary artery andits immediate branches in a secondary

lobule; these arteries measure approx-imately I mm and 0.5-0.7 mm in di-ameter, respectively; HRCT depictsthese vessels (29). However, a normalbronchiole supplying a secondarylobule has a wall thickness of approxi-mately 0.15 mm, which is beyond theresolution of HRCT. Therefore, nor-ma! airways in secondary pulmonarylobules are not detected at CT exami-nation (29).

consolidation

1 . Pathology.-Transudate, exudate,or tissue replacing alveolar air (1).

2. CT-Homogeneous increase inpulmonary parenchymal attenuationthat obscures the margins of vesselsand airway walls (30). An air broncho-gram may be present.

core structures

See “centrilobular structures.”

cyst

1. Pathology.-A round, circum-scribed space that is surrounded byan epithelial or fibrous wall of thick-ness, which may be uniform or varied,and that in the lung usually containsair but may contain liquid, semisolid,or solid material (31).

2. CT-A round, parenchymalspace with a well-defined wall; usu-ally air-containing when in the lungbut without associated pulmonaryemphysema; commonly used to de-scribe enlarged air spaces in end-stagefibrosis of idiopathic pulmonary fibro-

sis (31-33) and sarcoidosis (12,32), andalso in Langerhans cell histiocytosis(32-34) and lymphangiomyomatosis(32,33,35). See “bulla,” “cystic airspace,” and “honeycomb cysts.”

cystic air space

Enlarged unit of peripheral air-con-taming lung, surrounded by a wall ofvariable thickness, which may be thinas in lymphangiomyomatosis (35), or

may be thick as in idiopathic pulmo-nary fibrosis (31-33). See “bulla,”“cyst,” and “honeycomb cysts.”

dependent increased attenuation

See “dependent opacity.”

dependent opacity

Subpleural increased attenuation independent lung. The increased atten-uation disappears when the region oflung is nondependent. May also ap-pear as a subpleural line.

distal acinar emphysema

I . Pathology.-Emphysema charac-terized by predominant involvementof alveolar ducts and sacs, characteris-tically in subpleural lung and adja-cent to interlobular septa and vessels(24,26).

2. CT-Emphysema characterizedby subpleural regions of low attenua-tion or bullae separated by intact in-terlobular septa (24,26). Synonym:paraseptal emphysema.

distortion

See “architectural distortion.”

emphysema

1 . Pathology.-Permanently enlargedair spaces distal to the terminal bron-chiole, accompanied by destroyedalveolar walls (24,26). Absence of “ob-vious fibrosis” historically has beenregarded as an additional criterion(24), but the validity of that criterionrecently has been called into question(36,37).

2. CT-Focal region or regions oflow attenuation, usually without vis-ible walls, resulting from actual orperceived enlarged air spaces anddestroyed alveolar walls (24,29,38,39).May be associated with air trapping(40). See also “bulla,” “bullous emphy-sema,” “centrilobular emphysema,”“cyst,” “cystic air space,” “distal aci-

nar emphysema,” “panlobular emphy-sema,” and “paraseptal emphysema.”

fungus ball

A masslike collection of intertwinedhyphae, usually Aspergillus species,

matted together by mucus, fibrin, andcellular debris and colonizing a pul-monary cavity caused by prior disease(eg, sarcoidosis). May move to a de-pendent location when the patientchanges position. At CT, may show a“spongework” pattern, including fociof high attenuation (41). Synonym:mycetoma.

gas trapping

See “air trapping.”

ground-glass attenuation

See “ground-glass opacity.”

ground-glass opacity

Hazy increased attenuation of lung,but with preservation of bronchialand vascular margins; caused by par-tial filling of air spaces, interstitialthickening, partial collapse of alveoli,normal expiration, or increased capil-lary blood volume (14,15,30,42,43).Not to be confused with “consolida-

tion,” in which bronchovascular mar-gins are obscured. May be associatedwith an air bronchogram (43).

halo sign

Ground-glass opacity surroundingthe circumference of a nodule or mass(7,44). May be a sign of invasive as-

pergillosis (7) or hemorrhage of van-

ous causes (44).

honeycomb cysts

Cystic air spaces, usually of compa-rable diameter and on the order of0.3-1.0 cm in diameter, formed by thehoneycombing of interstitial pulmo-nary fibrosis (29,31,33).

honeycombing

I . Pathology.-Destroyed, fibrotic,and cystic lung, representing com-plete loss of acinar and bronchiolararchitecture as the end stage of fibres-ing lung disease (31-33,45).

2. CT-Clustered cystic air spaces,usually of comparable diameters onthe order of 0.3-1.0 cm but as much as2.5 cm, usually subpleural and charac-tenized by well-defined walls, whichare often thick (29,31-33,45). A CTfeature of diffuse pulmonary fibrosis.A diagnostic pitfall is that, in the pres-ence of underlying pulmonary em-

Volume 200 #{149}Number 2 Radiology #{149}329

physema, air-space consolidation canmimic this appearance.

interlobular septal thickening

See “septal line.”

intralobular lines

Fine linear opacities present in alobule when the intralobular intersti-tium is thickened. When numerous,they may appear as a fine reticular

pattern.

irregular linear opacity

Any linear opacity of irregularthickness of 1-3 mm, distinct from

interlobular septa, bronchovascularbundles, and nodular opacities (12).May be intralobular or extend throughseveral adjacent secondary lobules.

linear opacity

An elongated, thin line of soft-tis-sue attenuation. Rarely, calcificationor foreign material may increase theattenuation. See also “irregular linearopacity” and “subpleural line.”

lobular core structures

See “centrilobular structures.”

lobule

See “secondary pulmonary lobule.”

micronodule

Discrete, small, round, focal opacityof at least soft-tissue attenuation andwith a diameter no greater than 7 mm(17,42). Some authors have limited useof this term to a diameter of less than5 mm (13) or less than 3 mm (8,11).Other authors simply use the term“small nodule” (46). See “nodule.”

midlung window

A midlung region, characterized bythe absence of large blood vessels andby a paucity of small blood vessels,that corresponds to the minor fissureand adjacent peripheral lung (47).

mosaic oligemia

See “mosaic perfusion.”

mosaic perfusion

A patchwork of regions of variedattenuation, interpreted as secondary

to regional differences in perfusion(3). A more inclusive term than the

originally described “mosaic olige-mia” (48). Air trapping secondary tobronchial or bronchiolar obstructionmay also produce focal zones of de-creased attenuation, an appearancethat can be enhanced by using expi-ratory CT (8-10).

mycetoma

See “fungus ball.”

nodule

1. Pathology.-Small, approximately

spherical, circumscribed focus of ab-

normal tissue.2. Radiology.-Round opacity, at

least moderately well marginated andno greater than 3 cm in maximumdiameter. Some authors use the modi-fier “small” if the maximum diameterof the opacity is less than 1 cm (46).See also “micronodule.”

opacification

See “parenchymal opacification.”

panacinar emphysema

See “panlobular emphysema.”

panlobular emphysema

1 . Pathology.-Emphysema thatinvolves, more or less uniformly, allportions of the secondary lobules (24).It tends to predominate in the lowerlobes and is the form of emphysemaassociated with hereditary a1-proteaseinhibitor (a1-antitrypsin) deficiency.

2. CT.-Emphysema that tends toshow rather uniformly decreased pa-renchymal attenuation and a paucityof vessels (39). Severe panlobular em-physema may be indistinguishablefrom severe centnlobular emphysema,except on the basis of zonal distribution.Synonym: panacinar emphysema.

paraseptal emphysema

See “distal acinar emphysema.”

parenchymal band

Elongated opacity, usually severalmillimeters wide and up to about5-cm long, often extending to thepleura, which may be thickened andretracted at the site of contact (49).Originally described in asbestosis (49)but also a sign of focal fibrosis of non-specific cause.

parenchymal opacification

Increase in pulmonary attenuationthat may or may not obscure the mar-gins of vessels and airway walls. “Con-solidation” indicates that definition ofthese margins (excepting air broncho-grams) is lost, whereas “ground-glassopacity” indicates a lesser increase inattenuation, in which definition of themargins is preserved (14,30,43). When-ever possible, use of the more specificterms “consolidation” or “ground-glass opacity” is preferred.

peripheral

Referring to pulmonary structures

within 1-2 cm of any visceral pleuralsurface. See also “subpleural.”

pseudoplaque

An irregular band of peripheralpulmonary opacity adjacent to vis-ceral pleura that simulates the ap-pearance of a pleural plaque and isformed by the coalescence of smallnodules (eg, in coal-worker’s pneu-moconiosis) (17).

reticular pattern

See “reticulation.”

reticulation

Innumerable, interlacing line shad-ows that suggest a mesh. A descnip-tive term usually associated with in-terstitial lung diseases. May be fine,intermediate, or coarse. Synonym:reticular pattern.

secondary pulmonary lobule

1. Anatomy.-The smallest unit oflung surrounded by connective tissuesepta, according to Miller (27) andHeitzman et a! (28). These septa,

known as interlobular septa, are bestdeveloped in the periphery of theanterior, lateral, and juxtamediastinalregions of the upper and middle lobes,and in the periphery of the anteriorand diaphragmatic regions of thelower lobes (28,29,50). The septa tendto be incompletely developed or ab-sent elsewhere in the lungs. Miller’slobule ranges in size from 0.5 to 3.0cm and may contain 3-20 acini (51).

2. Anatomy.-The unit of lung sub-tended by any bronchiole that givesoff three to five terminal bronchioles,according to Reid (52). Connectivetissue septa are not part of this defini-tion. A small Miller’s lobule (0.5 cm)corresponds to a Reid’s lobule.

330 #{149}Radiology August 1996

3. CT.-Miller’s lobule is the sec-

ondary lobule that is identified with

CT (51). See also “centrilobular stnuc-hires.”

septal line

Thin linear opacity that come-sponds to an interlobular septum; tobe distinguished from centrilobularstructures. See “septal thickening.”

septal thickening

Abnormal widening of an interlob-ular septum or septa, usually causedby edema, cellular infiltration, or fi-brosis (16,29,53). May be smooth, in-regular, or nodular. See also “beadedseptum sign.”

signet-ring sign

A ring of opacity (usually repre-senting a dilated, thick-walled bron-chus) in association with a smaller,round, soft-tissue opacity (the adja-cent pulmonary artery or, rarely, di-lated bronchial artery) suggesting a“signet ring” (22). Usually this findingindicates bronchiectasis, but it mayalso occur in multifocal bronchioloal-veolar carcinoma and metastatic ad-enocarcinoma (22).

subpleural

Referring to pulmonary structuresthat are next to or near visceral pleura.

subpleural line

A thin curvilinear opacity, a fewmillimeters or less in thickness, usu-ally less than 1 cm from the pleuralsurface and paralleling the pleura(54,55). A nonspecific indicator of ate!-ectasis, edema, fibrosis, or inflamma-tion. See also “irregular linear opacity.”

traction bronchiectasis

Bronchial dilatation, which is com-monly irregular, in association withjuxtabronchial opacification that isinterpreted as representing retractile

pulmonary fibrosis (14,56).

traction bronchiolectasis

Bronchiolar dilatation in associa-tion with peribronchiolar opacifica-tion that is interpreted as represent-ing retractile pulmonary fibrosis (14).

tree-in-bud sign

Nodular dilatation of centrilobularbranching structures that resembles a

budding tree and represents exuda-tive bronchiolar dilatation (eg, in pan-bronchiolitis [23] or endobronchial

spread of active pulmonary tubercu-losis [57J). S

Acknowledgments: The committee thanksJanet E. Kuhlman, MD, Charles Kuhn Ill, MD,Theresa C. McLoud, MD, Lynne M. Reid, MD,Jacques Remy, MD, Stuart S. Sage!, MD, andEwald R. Weibel, MD for their helpful com-ments.

References

1. Tuddenham WJ. Glossary of terms forthoracic radiology: recommendations ofthe Nomenclature Committee of theFleischner Society. AJR 1984; 143:509-517.

2. Webb WR, Muller NL, Naidich DP. G!os-sary of CT terms. In: High-resolution CT ofthe lung. New York, NY: Raven, 1991; 157-159.

3. Webb WR, Muller NL, Naidich DP. Stan-dardized terms for high-resolution com-puted tomography of the lung: a proposedglossary. J Thorac Imaging 1993; 8:167-175.

4. MayoJR, Webb WR, Gould R, et al. High-resolution CT of the lungs: an optimal ap-proach. Radiology 1987; 163:507-510.

5. Aquino SL, Kee ST, Warnock ML, Gamsu

G. Pulmonary aspergillosis: imaging find-ings with pathologic correlation. AJR 1994;

163:811-815.6. Gefter WB, Albelda SM, Talbot GH, Gerson

SL, Cassileth PA, Miller WT. Invasive pu!-monary aspergillosis and acute leukemia:limitations in the diagnostic utility of theair crescent sign. Radiology 1985; 157:605-610.

7. Kuhlman JE, Fishman EK, SiegelmanInvasive pulmonary aspergil!osis in acuteleukemia: characteristic findings on CT, theCT halo sign, and the role of CT in earlydiagnosis. Radiology 1985; 157:611-614.

8. Zerhouni EA, Naidich DP, Stitik FP, KhouriNF, Siegelman 55. Computed tomogra-phy of the pulmonary parenchyma. II. In-terstitial disease. J Thorac Imaging 1985;1:54-64.

9. Webb WR, Stern EJ, Kanth N, Gamsu G.Dynamic pulmonary CT: findings in

healthy adult men. Radiology 1993; 186:117-124.

10. Hansell DM, Wells AU, Rubens MB, ColePJ. Bronchiectasis: functional significanceof areas of decreased attenuation at expira-tory CT. Radiology 1994; 193:369-374.

11. Brauner MW, Lenoir 5, Grenier P, Cluze! P,Battesti JP, Valeyre D. Pulmonary sar-coidosis: CT assessment of lesion reversibil-ity. Radiology 1992; 182:349-354.

12. MurdochJ, Muller NL. Pulmonary sar-coidosis: changes on follow-up CT exami-nation. AJR 1992; 159:473-477.

13. Remy-Jardin M, Remy J, Wallaert B, MullerNL. Subacute and chronic bird breederhypersensitivity pneumonitis: sequentialevaluation with CT and correlation withlung function tests and bronchoalveolarlavage. Radiology 1993; 189:111-118.

14. Remy-Jardin M, Giraud F, RemyJ, CopinMC, Gosselin B, Duhamel A. Importance

of ground-glass aftenuation in chronicdiffuse infiltrative lung disease: patho-logic-a correlation. Radiology 1993; 189:693-698.

15. Owens CM, Evans TW, Keogh BF, HansellDM. Computed tomography in estab-lished adult respiratory distress syndrome:correlation with lung injury score. Chest1994; 106:1815-1821.

16. Munk PL, Muller NL, Miller RR, OstrowDN. Pulmonary lymphangitic carcinoma-tosis: CT and pathologic findings. Radiol-ogy 1988; 166:705-709.

17. Remy-Jardin M, Beuscart R, Sault MC, Mar-quette CH, RemyJ. Subpleural micronod-ules in diffuse infiltrative lung diseases:evaluation with thin-section CT scans. Ra-diology 1990; 177:133-139.

18. Reid LM. Reduction in bronchial subdivi-sion in bronchiectasis. Thorax 1950; 5:233-247.

19. Kang EU, Miller RR, Muller NL. Bronchi-ectasis: comparison of preoperative thin-section CT and pathologic findings in re-sected specimens. Radiology 1995; 195:649-654.

20. Naidich DP, McCauley DI, Khouri NF, Sti-tik FP, Siegelman 55. Computed tomog-raphy of bronchiectasis. J Comput AssistTomogr 1982; 6:437-444.

21. Grenier P. Maurice F, Musset D, Menu Y,Nahum H. Bronchiectasis: assessment bythin-section CT. Radiology 1986; 161:95-99.

22. McGuinness G, Naidich DP, Leitman BS,McCauley DI. Bronchiectasis: CT evalua-tion. AJR 1993; 160:243-259.

23. Akira M, Kitatani F, Yong-Sik L, et a!. Dif-fuse panbronchiolitis: evaluation with high-resolution CT. Radiology 1988; 168:433-438.

24. Snider GL, Kleinerman J, Thurlbeck WM,Bengali ZH. The definition of emphy-sema: report of a National Heart, Lung,and Blood Institute, Division of Lung Dis-eases workshop. Am Rev Respir (Ms 1985;

132:182-185.25. Foster WL, Pratt PC, Roggli VL, Godwin

JD, Halvorsen RAJr, Putman CE. Centri-lobular emphysema: CT-pathologic correla-tion. Radiology 1986; 159:27-32.

26. Thurlbeck WM, Muller NL. Emphysema:definition, imaging, and quantification. AJR1994; 163:1017-1025.

27. Miller WS. The lung. 2nd ed. Springfield,Ill: Thomas, 1947.

28. Heitzman ER, Markarian B, Berger I, Dailey

E. The secondary pulmonary lobule: apractical concept for interpretation of chestradiographs. I. Roentgen anatomy of thenormal secondary pulmonary lobule. Radi-ology 1969; 93:507-512.

29. Webb WR, Stein MG, Finkbeiner WE, ImJG, Lynch D, Gamsu G. Normal and dis-eased isolated lungs: high-resolution CT.Radiology 1988; 166:81-87.

30. Leung AN, Miller RR, Muller NL. Paren-chymal opacification in chronic infiltrativelung diseases: CT-pathologic correlation.Radiology 1993; 188:209-214.

31. Genereux GP. The end-stage lung: patho-genesis, pathology, and radiology. Radiol-ogy 1975; 116:279-289.

32. Primack SL, Hartman TE, Hansell DM,Muller NL. End-stage lung disease: CTfindings in 61 patients. Radiology 1993;

189:681-686.33. Muller NL, Miller RR. Computed tomog-

raphy of chronic diffuse infiltrative lungdisease. Am Rev Respir Dis 1990; 142:1206-

1215 (part 1), 1440-1448 (part 2).34. Moore ADA, Godwin JD, Muller NL, et a!.

Pulmonary histiocytosis X: comparison ofradiographic and CT findings. Radiology1989; 172:249-254.

35. Muller NL, Chiles C, Kullnig P. Pulmo-nary !ymphangiomyomatosis: correlation

of CT with radiographic and functionalfindings. Radiology 1990; 175:335-339.

36. Snider GL. Pathogenesis and terminologyof emphysema. AmJ Respir Crit Care Med1994; 149:1382-1383.

37. Cardoso WV, Thurlbeck WM. Pathogen-esis and terminology of emphysema (letter).AmJ Respir Crit Care Med 1994; 149:1383.

Volume 200 #{149}Number 2 Radiology #{149}331

38. Miller RR, Muller NL, Vedal 5, MorrisonNJ, Staples CA. Limitations of computed

tomography in the assessment of emphy-sema. Am Rev Respir Dis 1989; 139:980-983.

39. Spouge D, Mayo JR. Cardoso W, MullerNL. Panacinar emphysema: CT andpathologic findings. J Comput Assist To-mogr 1993; 17:710-713.

40. Knudson RJ, Standen JR. Kaltenborn WT,et a!. Expiratory computed tomographyfor assessment of suspected pulmonaryemphysema. Chest 1991; 99:1357-1366.

41. Roberts CM, Citron KM. Strickland B. In-trathoracic aspergilloma: role of CT in di-agnosis and treatment. Radiology 1987;165:123-128.

42. Remy-Jardin M, RemyJ, Gosselin B, BecetteV. Edme JL. Lung parenchymal changessecondary to cigarette smoking: patho-logic-CT correlations. Radiology 1993; 186:643-651.

43. Remy-Jardin M, Remy J, Giraud F, Wat-tinne L, Gosselin B. Computed tomogra-phy assessment of ground-glass opacity:semiology and significance. J Thorac Imag-ing 1993; 8:249-264.

44. Primack SL, Hartman TE, Lee KS, Muller

NL. Pulmonary nodules and the CT halosign. Radiology 1994; 190:513-515.

45. Heppleston AG. Pathology of honeycomblung. Thorax 1956; 11:77-93.

46. Webb WR, Muller NL, Naidich DP. High-resolution CT of the lung. 2nd ed. NewYork, NY: Lippincott-Raven, 1996.

47. Goodman LR, Golkow RS, Steiner RM, etat The right mid!ung window: a poten-tia! source of error in computed tomogra-phy of the lung. Radiology 1982; 143:135-138.

48. Martin KW, Sage! SS, Siegel BA. Mosaicoligemia simulating pulmonary infiltrateson CT. AJR 1986; 147:670-673.

49. Aberle DR, Gamsu G, Ray CS, FeuersteinIM. Asbestos-related pleural and paren-chymal fibrosis: detection with high-reso-lution CT. Radiology 1988; 166:729-734.

50. Reid L, Rubino M. The connective tissuesepta in the foetal human lung. Thorax1959; 14:3-13.

51. Itoh H, Murata K, KonishiJ, Nishimura K,Kitaichi M, Izumi T. Diffuse lung disease:pathologic basis for the high-resolutioncomputed tomography findings. J ThoracImaging 1993; 8:176-188.

52. Reid L. The secondary lobule in the adulthuman lung, with special reference to itsappearance in bronchograms. Thorax 1958;13:110-115.

53. Heitzman ER, Markarian B, Berger I, DaileyE. The secondary pulmonary lobule: apractical concept for interpretation of chestradiographs. II. Application of the ana-tomic concept to an understanding ofroentgen pattern in disease states. Radio!-ogy 1969; 93:513-519.

54. Yoshimura H, Hatakeyama M, Otsuji H, eta!. Pulmonary asbestosis: CT study ofsubpleura! curvilinear shadow. Work inprogress. Radiology 1986; 158:653-658.

55. Arai K, Takashima T, Matsui 0, Kadoya M,

Kamimura R. Transient subpleural curvi-linear shadow caused by pulmonary con-gestion.J Comput Assist Tomogr 1990; 14:87-88.

56. WestcottJL, Cole SR. Traction bronchiec-tasis in end-stage pulmonary fibrosis. Radi-ology 1986; 161:665-669.

57. Im JG, Itoh H, Shim YS, et a!. Pulmonarytuberculosis: CT findings-early active dis-ease and sequential change with antituber-culous therapy. Radiology 1993; 186:653-660.