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1 기관지천식의영상소견 종설 순천향대학교의과대학방사선과학교실박재성, 백상현 Radiologic Findings of Bronchial Asthma Jai Soung Park, M.D., Sang Hyun Paik, M.D. Department of Radiology, Soonchunhyang University School of Medicine Asthma is the most common disease of the lungs, and one that poses specific challenges for the physicians including radiologist. This article reviews for the clinical diagnosis, Radiologic features, and differential diagnosis of asthma, and outlines the radiologic features of the complications of asthma. Bronchial wall thickening and hyperinflation characterize the chest radiograph of the patients with asthma. On CT scan one may see airway wall thickening, thickened centrilobular structures, and focal or diffuse hyperlucency. Apparent bronchial dilatation may be seen, but the diagnosis of bronchiectasis should be made with caution. Quantification of changes in the airway wall and lung parenchyma may be valuable in understanding the mechanisms of asthma and in evaluating the effects of treatment. The challenge for the physician evaluating the images of a patient with asthma is to find complications. (Tuberc Respir Dis 2005; 59: ) 서 론 헌고찰과함께설명하고자한다. 기관지천식은다양한자극에대한과민성의증가로기도가폐쇄되나치료에의하여호전되는가역적인변화를특징으로한다 1. 임상적으로기관지확장제에반응을보이는기도폐쇄를보이면기관지천식으로진단할수있다. 잠재적인천식인경우에는 methacholine 같은흡입물질로기관의과민반응을유발시켜진단한다. 병리학적으로는기관지점막의손상및과다분비, 점막하층의부종과호산구성염증세포침윤, 때때로림프구나형질세포에의한기관지벽비후의소견들이보인다 2. 이러한만성염증은기도내의병리학적변화를일으키고, 기관지구조의현저한개형 (remodeling) 을일으키며 3, 점액분비선비대, 기저막비후, 평활근의과형성등의소견을동반한다. 저자들은기관지천식및천식과연관된각종폐질환의단순흉부사진과고해상전산화단층촬영 (high resolution computed radiography, HRCT) 소견을문 Address for correspondence : Jai Soung Park, M.D., Department of Radiology Soonchunhyang University Bucheon Hospital 1174 Jung-dong, Wonmi-ku, Bucheon Kyunggi-do , Korea Phone : ,3 Fax : jspark@schbc.ac.kr 기관지천식의단순흉부사진소견대부분천식환자의흉부사진소견은기관지벽비후와과통기 (hyperinflation) 이다. 또한드물지않게변연부의혈관감소, 중심부폐음영증가그리고폐문음영의증대등이관찰된다 4-6. 천식환자에있어서방사선학적이상소견은전반적으로소아에서더욱흔하고심하다. 이러한방사선학적소견은여러요소들에의해영향을받는데발병시기, 천식의중증정도, 다른질환의동반유무그리고천식에의한합병증등이다 4. 방사선학적이상과발병시기에대한연구를보면 15세이후에천식이발병한 117명의환자중흉부사진의이상은단한예였으나 15세이전에발병한환자들중에는 31% 에서이상소견을보였으며, 30세이후에발병한환자들중에는한예도보이지않았다 7. 질병의중증 (severity) 정도와흉부사진이상과의관계에대한연구에서중증천식을앓고있는 58명 (10-69세, 평균 33세 ) 의환자중 42명 (73%) 에서폐의과통기소견을보였다 8. 천식환자의단순흉부사진에서가장흔한소견은기관지벽비후로 48% 4 에서 71% 6 에이른다. Rubensteine 등은경, 중등도천식환자를대상으로단순흉 591

2 JS Park et al. : Radiologic findings of bronchial asthma 부사진에서보이는기관지벽비후와과통기소견이폐활량계 (spirometry) 보다진단에더높은민감도를보인다고하였다 9. 폐의과통기와호기시공기포획 (air trapping) 과같은방사선이상소견은급성중등도, 장기간의지속된경우혹은치료에반응이없는천식에서특징적이다. 과통기는소아환자, 10대이전에천식이발병한경우및입원치료가필요할정도로심한환자에서더흔하다 10. 공기포획의소견은기관지의폐쇄및개형과연관되어나타난다. 과통기로인해횡격막하강및후흉골공간 (retrosternal space) 의확장등의소견이보일수는있지만동반된폐기종없이천식만으로횡격막이평평해지거나하방으로볼록해지는경우는드물다. 실제로천식환자의대다수의단순흉부사진소견은정상이며심지어급성악화기에도폐용적은오히려감소하는것을볼수있다. 천식에대한여러연구자들의보고에도불구하고, 단순흉부사진은천식을진단하는데제한적이며급성천식에서도종종정상소견을보인다. 이상소견이있더라도그것은비특이적이다. 천식환자에서흉부방사선검사를시행하는이유는 1) 천명음 (wheezing) 을일으킬만한폐기종, 울혈성심질환, 기도폐쇄와같은다른질환을배제하고, 2) 기흉등의합병증을발견하는데목적이있다. 천식의고해상 CT 소견 HRCT는단순흉부사진보다기도의해부학적구조를정확하게나타내므로천식환자에있어서기관지협착의위치, 정도, 분포등에대한연구를가능하게했다. 또한 CT 영상으로부터얻은정보를분석하여기도질환의범위를정량적인수치로표현할수있게되었다. 창높이 (window level), 창넓이 (window width), 영상범위의크기 (field of view) 그리고재구성연산법등은 CT 영상의질과기관지내경및벽두께의측정에있어서정확성에많은영향을미친다. 특히창높이는기관지벽의두께를정량적으로분석하는연구에서중요한요소이다. 여러보고자들이가상기관지를 이용하여창높이와넓이에대하여연구를시행하였다. 이러한결과를기초로하여기관지내경및벽두께를측정할경우에는창높이를 -450 HU로사용하고있다 11,12. 기관지벽두께를측정하기위한최적의창넓이는 1,000HU에서부터 1,400HU까지이다. 창넓이가 1,000HU보다좁으면기관지벽이두껍게측정되고, 반면에 1,400 HU보다넓으면기관지벽의두께가얇게측정된다 13. 몇몇연구자들은적절한창높이와넓이로기관지내경을정확히측정할수있는가장작은기도의크기를 mm 라고주장하였다 4,14,15. HRCT에서기관지천식의가장흔한이상소견들은기관지벽비후, 기관지내경감소, 기관지확장, 점액저류, 혈관음영의감소및공기포획등이다 4, 기관지병변의분포는종종비균질적이어서, 어느부위의기관지벽과내경은정상소견을보이나다른부위의기관지벽은두껍고내경이좁거나확장될수있다. 기관지벽비후 (Bronchial Wall Thickening) 천식환자에서기관지벽비후에대한보고는다양하다. 한연구에서는천식환자 48명중 44명 (92%) 이기관지벽비후의소견을보였는데이는정상대조군의 27명중 5명 (19%) 만기관지벽의비후를보인것보다통계학적으로유의하게높았다 6. 다른연구에서는 HRCT에서기관지벽비후소견이 39명의천식환자중 44%, 정상인 14명중 14% 에서보인다고하였다 18. 일반적으로기관지벽의비후는기관지외경에대한기관지벽두께비 (T/D ratio) 를 ( 외경-내경 ) / 외경으로, 또는전체기관지의면적에대한기관지벽면적의비 (Wall Area%, WA%) 를 {π( 외경 /2) 2 -π( 내경 /2) 2 } / π( 외경 /2) 2 으로측정하고있다 (Figure 1). Awadh 등은천식의중증에따라 3군 { 치명적천식 (near fatal asthma), 중등도천식및경증천식 } 으로분류하고, 정상대조군과기관지벽두께및면적의비를비교한결과천식환자군이대조군보다두개의측정치모두에서증가되어있었으며, 치명적및중등도천식환자군이경증천식환자군에비하여기관지벽이두꺼워졌음을보고하였다 19. 국내에서도최등은천식환자의기관지벽두께의비가 0.48 ± 0.08로정상대조군의 592

Tuberculosis and Respiratory Diseases Vol. 59. No. 6, Dec. 2005 Figure 1.

기관지벽은구조의개형에의하여일시적으로비가역적인변화를보이기도한다 (Figure 2).

천식환자에서보이는기관지벽비후소견은염증에의한점막하층의비후와기관지평활근비대로인한근층비후그리고기관지주위섬유화의요소들이복합되어생긴것으로추정한다 23. Kasahara 등은기관지경생검으로 (C) Figure 2.

bronchi in the right middle and lower lung zones, with mild hyperinflation.

3 Tuberculosis and Respiratory Diseases Vol. 59. No. 6, Dec Figure 1. Measurement of bronchial and lumen diameter with calculation of WA% and T/D ratio 0.40 ± 0.08 보다통계학적으로유의하게증가하였다고보고하였다 22. 기관지벽은구조의개형에의하여일시적으로비가역적인변화를보이기도한다 (Figure 2). 한보고에서는 CT 검사를시행한 10명의급성천식환자를대상으로집중적인스테로이드치료를시행한 2주후에시행한추적 CT 검사에서기관지벽두께의변화가없었다고하였다 4. 천식환자에서보이는기관지벽비후소견은염증에의한점막하층의비후와기관지평활근비대로인한근층비후그리고기관지주위섬유화의요소들이복합되어생긴것으로추정한다 23. Kasahara 등은기관지경생검으로 (C) Figure 2. Bronchial wall thickening in patient with bronchial asthma Initial chest radiograph shows visible wall thickening of bronchi in the right middle and lower lung zones, with mild hyperinflation. Follow up chest radiograph after 16 months shows no interval change of bronchial wall thickening in the right middle and lower lung zones. (C) Initial HRCT scan obtained at level of basal segmental bronchi shows diffuse and moderate degree of bronchial wall thickening (arrows) during end-inspiration (left) and expiration (right). 593

JS Park et al. : Radiologic findings of bronchial asthma 얻은병리조직에서기관지의점막하층 (epithelial reticular basement membrane) 의두께를측정한후고해상 CT에서측정한기관지벽두께및면적의비와비교할때통계학적으로유의한연관성이있음을증명하였다 21.

비슷한연령대의정상인과비교할때천식환자의기관지내경의면적비는직경이작은기관지에서상대적으로더감소되어있다 17. 기관지내경을평가하는다른방법으로기관지확장을평가할때적용했던것과마찬가지로동행하는폐동맥의내경과비교하는방법이있다 6,18.

저자들은 methacholine 에의한기도수축으로 (C) Figure 3. Airway narrowing in response to inhaled methacholine in normal subjects and in patients with asthma.

4 JS Park et al. : Radiologic findings of bronchial asthma 얻은병리조직에서기관지의점막하층 (epithelial reticular basement membrane) 의두께를측정한후고해상 CT에서측정한기관지벽두께및면적의비와비교할때통계학적으로유의한연관성이있음을증명하였다 21. 또한점막하층의두께가기관지벽전체의두께와비례함을 CT를통하여간접적으로증명하였다. 이런섬유화, 근육비대그리고염증성비후들의상대적인비율에따라기관지벽비후소견이치료후가역적혹은비가역적일수있다 4,24. 기도협착 (Airway Narrowing) 천식환자의기도협착은무작위로선택한기도에서전체기관지면적에대한내경면적의비를평가 함으로써측정할수있다 비슷한연령대의정상인과비교할때천식환자의기관지내경의면적비는직경이작은기관지에서상대적으로더감소되어있다 17. 기관지내경을평가하는다른방법으로기관지확장을평가할때적용했던것과마찬가지로동행하는폐동맥의내경과비교하는방법이있다 6,18. 중등도이상의천식환자들은경도의천식환자나정상인에비하여기관지외경에비해기관지벽이훨씬두껍고전체기관지 ( 외경 ) 의면적에서기관지벽부분이차지하는비율이더증가한다 19. Okazawa 등은 6명의정상인과 6명의경증 / 중등도천식환자를대상으로 methacholine 자극검사전후촬영한 CT에서천식환자와정상인모두기관지내경이감소하는것을발견하였다 17. 저자들은 methacholine 에의한기도수축으로 (C) Figure 3. Airway narrowing in response to inhaled methacholine in normal subjects and in patients with asthma. Bronchial diameter of the asthmatic subjects (C: pre-metacholine challenge, D: post-methacholine challenge) are significantly decreased and that the bronchial wall area does not change after bronchoconstriction (arrowheads) whereas it decreases in normal subjects (arrows) (A: pre-methacholine challenge, B: post-methacholine challenge). (D) 594

5 Tuberculosis and Respiratory Diseases Vol. 59. No. 6, Dec 정상인에서는기관지벽이차지하는면적이감소하지만, 천식환자의기관지벽의면적감소가없었다. 이는아마도주변폐조직의탄성반동력이감소하여기도벽이좀더뻣뻣해지고부종이생긴것으로추정하였다 17. 다른보고자들은 methacholine 흡입이후전반적인기관지수축이있음을발견하였고중간크기의기관지 ( 내경이 2-4mm 정도 ) 가대부분이었다고보고하였다 25. 정상인에서는기관지협착이생기는동안기관지벽의두께가감소하며, 이소견은내경이 6mm 이하의기도에서더욱뚜렷하였다 25. 기관지수축제주입전후의기도변화를비교하기위한 CT 촬영 (Figure 3) 에서한번흡기또는호기동안 1mm 절편영상으로폐의전체를얻을수있는나선형 CT 혹은다중검출 CT(Maltidector row Computed tomgraphy, MDCT) 가유용하게사용되고있다. 기관지확장 (Bronchial Dilatation) 천식환자의기관지는확장될수있는데그기준은기관지내경과동행하는폐동맥의직경의비로결정할수있다 6,18. 임상적으로알레르기성기관지폐아스페르길루스증을동반하지않은천식환자에서기관지확장의소견을보이는비율은연구에따라 18% 에서부터 77% 까지다양하게보고되고있고, 이러한비율은정상대조군에비해서유의하게높다. 예를들어한연구에서 CT를시행한 39명의천식환자중 31% 에서기관지확장의소견이보였고, 정상인은 14 명중 14% 에서기관지확장의소견이보였다 18. 일반적으로정상인에서기관지의내경은동행하는폐동맥에비하여 5% 에서 20% 까지더크다고보고되어있다 6,18. 기관지확장에대한다른설명으로동행하는폐동맥의직경이감소하여그결과로상대적으로기관지내경이커보인다는주장이있다. 최근보고에따르면기관지 / 동맥비는고지대에서검사를시행한환자에서더크게나타났는데그이유는고지대주민들은저산소증에의한혈관수축때문에상대적으로기관지내경이크게보인다고설명하였다 26. 어떤천식환자에서는실제기관지내경은같지만두꺼워진 기관지벽때문에더크게보이는착시현상으로주변혈관에비하여기관지가확장된것처럼보일수있다고하였다 26. 천식환자에서기관지확장의원인으로는반복적인염증반응에의한지속적인손상, 임상적으로나타나지않은알레르기성기관지폐아스페르길루스증이동반되었기때문이거나유년기에심한감염성질환을알았던경우등이포함된다. 천식환자에서기관지확장이보이는비율을 CT로조사한연구에서천식환자 48명중 37명, 대조군 27명중 16명에서적어도한개이상의기관지에서동행하는폐동맥보다내경이확장된소견을보였다 6. 천식환자의확장된기관지는연속된 CT 절편에서정상기관지에서보이는점점가늘어지는소견이없으며주변동맥의내경에비해 1.5배이상커진기관지도없었다 6. 이런소견을고려해볼때, 경도의기관지확장소견은천식환자뿐만아니라정상대조군에서도보일수있다. 천식환자에있어서폐동맥직경의감소는부분적인공기포획과연관된저산소성폐혈관수축에기인한다고생각할수있다. 이러한저산소성폐동맥수축의영향으로기관 / 동맥비의가시적인과평가가있을수있기때문에천식환자에서경증의원통형의기관지확장 (cylindrical bronchiectasis) 을평가할때는주의를해야한다 (Figure 4). 공기포획 (Air Trapping) 천식환자의다른 HRCT 소견으로는국소적인저음영및혈관의감소그리고공기포획등이있다 18,27. 이런소견들은무증상의천식환자에서도흔히관찰되는폐환기-관류이상의결과이고이는방사선동위원소검사에서잘나타난다 28. 한연구자는천식환자의호기 HRCT에서공기포획이약 50% 에서보이며정상인에서는 14% 에서보인다고보고하였다 18. 또한폐기능검사에서 FEV1이 80% 이상인정상에가까운천식환자에서도공기포획이 45% 에서, 60%< FEV1<79% 인경우는 50% 에서, FEV1이 60% 미만인환자에서는 67% 에서보인다고하였다 18. 국내에서도천식환자의 HRCT에서공기포획을정량분석한황등의보고에의하면공기포획의범위는 FEV 1 및 595

JS Park et al. : Radiologic findings of bronchial asthma Figure 4. Bronchial dilatation in patients with bronchial asthma.

hypoxic pulmonary vasoconstriction (arrows).

bronchiectasis. Figure 5. Air trapping in patient with bronchial asthma.

HRCT scan obtained at same level shows geographic air trapping in both basal lungs during full expiration. MEFR과통계학적으로유의한상관관계를보였다 29.

6 JS Park et al. : Radiologic findings of bronchial asthma Figure 4. Bronchial dilatation in patients with bronchial asthma. HRCT scan obtained at level of basal segmental bronchi shows visual overestimation of bronchoarterial ratio at area of low attenuation (air trapping) due to hypoxic pulmonary vasoconstriction (arrows). HRCT scan of another patients with bronchial asthma shows tubular dilatation of bronchi (arrowheads) at normal ventilated lung, making diagnosis of cylindrical bronchiectasis. Figure 5. Air trapping in patient with bronchial asthma. HRCT scan obtained at level of liver dome shows diffuse bronchial wall thickening without area of low attenuation during end-inspiration. HRCT scan obtained at same level shows geographic air trapping in both basal lungs during full expiration. MEFR과통계학적으로유의한상관관계를보였다 29. 폐음영감소의정도는평균폐음영밀도를 densitometry를이용하여측정하거나기준치 (-900HU) 이하의 CT 음영을가지는폐의영역을전폐폐영역에대한비율로정량분석할수있다 16. 연구자들은 18명의천식환자와 22명의정상인을대상으로최대호기시에횡격막상부에서얻어진 CT 영상을분석한결과정상대조군보다천식환자에서통계학적으로유의하게음영이낮은것을확인하였다 16. 최근 Gevenois 등은 10명의천식환자를대상으로시행한흡기 CT에서의폐음영은급성공기포획이나만성과통기 에의해영향을받지않는다고주장하였으며, 따라서호기 CT 검사만이천식환자의공기포획의정도를평가할수있는유용한검사방법이라고보고하였다 30 (Figure 5). 흡기와호기 CT에서음영의밀도수치를정량적으로비교하면폐음영의감소가폐기종에의한것인지천식에의한것인지를구별할수있다. 천식환자에서저음영부위는공기포획뿐만아니라중심소엽성폐기종에서도관찰된다. 천식환자에서 CT 검사는폐기종의정도를동시에나타낼수있는가치있는검사이다

Tuberculosis and Respiratory Diseases Vol. 59. No. 6, Dec. 2005 Figure 6. Centrilobular thickening in patients with bronchial asthma.

mucoid impaction in small airway or peribronchiolar infiltration. 점액저류 (Mocoid Impaction) 점액저류는천식환자의약 21% 에서보고되고있으며이런소견은치료후소멸될수있다 4.

7 Tuberculosis and Respiratory Diseases Vol. 59. No. 6, Dec Figure 6. Centrilobular thickening in patients with bronchial asthma. HRCT scan obtained at level of liver dome and basal segmental bronchi shows extensive or mild prominent centrilobular and branching linear nodules in the right middle and lower lobes, suggesting mucoid impaction in small airway or peribronchiolar infiltration. 점액저류 (Mocoid Impaction) 점액저류는천식환자의약 21% 에서보고되고있으며이런소견은치료후소멸될수있다 4. 분지상혹은중심소엽성결절음영은천식환자의 10% 에서 21% 까지관찰되며 (Figure 6) 때때로나무의꽃봉오리같은모양 (Tree-in-bud) 도관찰된다고보고하였다 6. 이러한소견은점액저류뿐만이아니라세기관지벽비후, 염증혹은근층의비대를반영한다. Lee 등은치명적천식에서중심소엽성결절등의소기도병변이기관지벽비후나공기포획보다연관성이있음을최근보고하였다 32. 합병증을동반한천식의방사선학적소견천식과흔히동반되는질환및천식의합병증은단순흉부사진에서기강경화 (airspace consolidation), 무기폐, 점액저류, 기흉, 기종격동, 그리고알레르기성기관지폐아스페르길루스증 (allergic bronchopulmonary aspergillosis) 등이다. 알레르기성기관지폐아스페르길루스증을제외하고는대부분의합병증들이성인보다는소아에호발한다. 성인천식환자 1,016명에대한후향적연구에의하면입원당시단순흉부사진의약 8.2% 에서기흉등의합병증을관찰할수있 었다 33. 천식환자의단순흉부사진에서기강경화는감염성질환이주원인이나알레르기성기관지폐아스페르길루스증이동반과관계없이호산구성폐침윤이원인이되기도한다. 무기폐는아분절성에서부터엽성까지다양하게올수있으며, 간혹한쪽폐전체에도올수있다. 그러나무기폐는급성발병, 호흡기감염또는천식의악화를반드시동반하지는않는다. 이러한무기폐는성인및소아모두에서우중엽에가장잘호발한다 34. 무기폐의원인은기도의점액저류및소기도의점액플러그가주원인이다. 소아에서는무기폐와기강경화가동시에오는경우도많다 35. 성인천식환자에서는기흉은빈도가매우적은합병증이다. 보고에의하면 556명의성인천식환자중단지 3명만이기흉이발생하였으며 36, 다른보고에서도기흉의빈도는 1:300에서 1:1,100 등으로보고되고있다 37. 기흉은 positive pressure ventilation을받는천식환자에서발생한긴장성기흉 (tension pneumothorax) 을제외하고는거의사망의원인은되지않는다. 성인천식환자에서기종격동은기흉과마찬가지로빈도가매우낮으며, 보고에의하면성인환자 566명중 2명에서기종격동이발생하였다 36. 그러나소아에서는비교적드물지않게기종격동이발생하는데소아천식으로입원한환아 515명중 5.4% 에서발생하 597

8 JS Park et al. : Radiologic findings of bronchial asthma 였다는보고가있으며 34, 이는기흉보다약 10배이상의빈도이다 38. 천식으로입원이필요한모든환자에서단순흉부사진의촬영을권하는데, 이가운데약 9% 에서치료방침을변경할정도의방사선소견을보였다 35. 단순흉부사진의촬영은기계호흡의시행전에반드시필요하며, 천식의치료에반응이없을경우에도다른원인의발견을위하여필요하다. 천명음이들리는기타폐병변 호흡곤란을주소로내원한젊은환자의청진에서천명음이들리고, 단순흉부사진에서일견하여이상이없으면, 천식으로진단하려는경향이있다. 그러나청진상천명음이들리며천식과감별해야할질환군은성대의기능장애, 기도폐쇄, 기관지결석또는침윤성폐질환에의한소기도폐쇄및심부전등이다. 기도폐쇄소견은기관분기구에위치하는경우를제외하면비교적정면및측면단순흉부사진에서잘관찰할수있다. 기관이나큰기관지에국소적으로폐쇄를일으키는질환은양성및악성종양과기관절개술또는기관내삽관의합병증등이다. 미만성으로폐쇄를일으키는질환은유육종증 (sarcoidosis), 베게너육아종증 (Wegener s granulomatosis), 유전분증 (amyloidosis), 과민성폐장염 (hypersensitivity pneumonitis) 등의침윤성질환군과재발성다발성연골염 (relapsing polychondritis), 기관기관지골연골증식증 (tracheobronchopathia osteochodroplastica) 등의연골에발생하는질환군이있다. MDCT 후 3차원입체영상 (three-dimensional rendering) 및다면재구성 (three-planar reformation) 이수술계획수립을위한해부학적구조를파악하는데매우도움이되고있다. 참고문헌 1. American Thoracic Society. Standards for the diagnosis and case of patients with chronic obstructive pulmonary disease and asthma: the ATS board of directors, Nov Am Rev Respir Dis 1987;136: Bousquet J, Chanez P, Lacoste JY, Barneon G, Ghavanian N, Enander I, et al. Eosinophilic inflammation in asthma. N Eng J Med 1990;323: Bousquet J, Jeffery PK, Busse WW, Johnson M, Vignola AM. Asthma: from bronchoconstriction to airways inflammation and remodeling. Am J Respir Crit Care Med 2000;161: Paganin F, Trussard V, Seneterre E, Chanez P, Giron J, Godard P, et al. Chest radiography and high resolution computed tomography of the lungs in asthma. Am Rev Respir Dis 1992;146: Webb WR. Radiology of obstructive pulmonary disease. AJR Am J Roentgenol 1997;169: Lynch DA, Newell JD, Tschomper BA, Cink TM, Newman LS, Bethel R. Uncomplicated asthma in adults: comparison of CT appearance of the lungs in asthmatic and healthy subjects. Radiology 1993;188: Hodson ME, Simon G, Batten JC. Radiology of uncomplicated asthma. Thorax 1974;29: Rebuck AS. Radiological aspects of severe asthma. Australas Radiol 1970;14: Rubenstein HS, Rosner BA, LeMay M, Neidorf R. The value of the chest X-ray in making the diagnosis of bronchial asthma. Adolescence 1993;28: Blackie SP, al-majed S, Staples CA, Hilliam C, Pare PD. Changes in total lung capacity during acute spontaneous asthma. Am Rev Respir Dis 1990;142: Webb WR, Gamsu G, Wall SD, Cann CE, Proctor E. CT of a bronchial phantom: factors affecting appearnce and size measurements. Invest Radiol 1984;19: McNamara AE, Müller NL, Okazawa M, Amtorp J, Wiggs BR, Pare PD. Airway narrowing in excised canine lungs measured by high-resolution computed tomography. J Appl Physiol 1992;73: Bankier AA, Fleischmann D, Mallek R, Windisch A, Winkelbauer FW, Kontrus M, et al. Bronchial wall thickness: appropriate window settings for thin section CT and Radiologic-anatomic correlation. Radiology 1996;199: Amirav I, Kramer S, Grunstein MM, Hoffman EA. Assessment of methacholine-induced airway constriction with ultrafast high-resolution computed tomography. J Appl Physiol 1993;75: Herold CJ, Brown RH, Mitzner W, Links JM, Hirshman CA, Zerheuni EA. Assessment of pulmonary airway reactivity with high-resolution CT. Radiology 1991;181: Newman KB, Lynch DA, Newman LS, Ellegood D, Newell JD Jr. Quantitative computed tomography detects air trapping due to asthma. Chest 1994;106: Okazawa M, Müller NL, McNamara AE, Child S, 598

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¼Û±âÇõ 223 Table 1. Results of FEV 1.0, Methacholine Challenge Test, and Exercise Provocation Test in Eight Patients Who Performed PFT Pts Tests 1 2 3 4 5 6 7 8 FEV 1.0 (%pred) 66.6 88.8 120 101 90.5 95.4 91.6