Original Article pissn 1738-2637 / eissn 2288-2928 J Korean Soc Radiol 2015;73(4):216-224 http://dx.doi.org/10.3348/jksr.2015.73.4.216 Predicting Factors for Conversion from Fluoroscopy Guided Percutaneous Transthoracic Needle Biopsy to Cone-Beam CT Guided Percutaneous Transthoracic Needle Biopsy Kang Ji Lee, MD 1, Young Min Han, MD 1,2,3, Gong Yong Jin, MD 1,2, Ji Soo Song, MD 1 1 Department of Radiology, 2 Research Institute of Clinical Medicine, 3 Institute of Cardiovascular Research, Chonbuk National University Hospital and Medical School, Jeonju, Korea Purpose: To evaluate the predicting factors for conversion from fluoroscopy guided percutaneous transthoracic needle biopsy (PTNB) to cone-beam CT guided PTNB. Materials and Methods: From January 2011 to December 2012, we retrospectively identified 38 patients who underwent cone-beam CT guided PTNB with solid pulmonary lesions, and 76 patients who underwent fluoroscopy guided PTNB were matched to the patients who underwent cone-beam CT guided PTNB for age, sex, and lesion location. We evaluated predicting factors such as, long-axis diameter, short-axis diameter, anterior-posterior diameter, and CT attenuation value of the solid pulmonary lesion affecting conversion from fluoroscopy guided PTNB to conebeam CT guided PTNB. Pearson χ 2 test, Fisher exact test, and independent t test were used in statistical analyses; in addition, we also used receiver operating characteristics curve to find the proper cut-off values affecting the conversion to cone-beam CT guided PTNB. Results: Short-axis, long-axis, anterior-posterior diameter and CT attenuation value of the solid pulmonary lesion in patients who underwent fluoroscopy guided PTNB were 2.70 ± 1.57 cm, 3.40 ± 1.92 cm, 3.06 ± 1.81 cm, and 35.67 ± 15.70 Hounsfield unit (HU), respectively. Short-axis, long-axis, anterior-posterior diameter and CT attenuation value of the solid pulmonary lesion in patients who underwent cone-beam CT guided PTNB were 1.60 ± 1.30 cm, 2.20 ± 1.45 cm, 1.91 ± 1.99 cm, and 18.32 ± 23.11 HU, respectively. Short-axis, long-axis, anterior-posterior diameter, and CT attenuation value showed a significantly different mean value between the 2 groups (p = 0.001, p < 0.001, p = 0.003, p < 0.001, respectively). Odd ratios of CT attenuation value and short-axis diameter of the solid pulmonary lesion were 0.952 and 0.618, respectively. Proper cut-off values affecting the conversion to cone-beam CT guided PTNB were 1.65 cm (sensitivity 68.4%, specificity 71.1%) in short-axis diameter and 29.50 HU (sensitivity 65.8%, specificity 65.8%) in CT attenuation value. Conclusion: Low CT attenuation value and small short-axis diameter of the solid pulmonary lesion affect conversion from fluoroscopy guided PTNB to cone-beam CT guided PTNB. Index terms Percutaneous Transthoracic Needle Biopsy Cone-Beam CT Solid Pulmonary Lesion Fluoroscopy Predicting Factors Received February 17, 2015 Revised August 4, 2015 Accepted August 7, 2015 Corresponding author: Young Min Han, MD Department of Diagnostic Radiology, Chonbuk National University Medical School and Hospital, 20 Geonji-ro, Deokjin-gu, Jeonju 54907, Korea. Tel. 82-63-250-1176 Fax. 82-63-272-0481 E-mail: ymhan@jbnu.ac.kr This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 서론 경피적흉부생검 (percutaneous transthoracic needle biopsy; 이하 PTNB) 은폐병변을병리학적으로진단하기위해서사용 하는잘알려진시술이며, 특히악성이의심되는폐병변에대해 서는유용하면서간편한시술이다 (1). 일반적으로는투시조영 216 Copyrights 2015 The Korean Society of Radiology
이강지외 유도하경피적흉부생검이쉽게이용할수있는방법이지만, 너무작거나, 잘보이지않거나, 또는생검하기에위험한위치에있는폐병변은전산화단층촬영 (computed tomography; 이하 CT) 또는전산화단층촬영투시 (CT fluoroscopy) 유도하생검을시행하는것이안전하다고알려져있다 (1, 2). CT를이용한경피적흉부생검은악성이의심되는폐병변에대해서안전한방법이며악성진단의민감도는 90~97% 로보고되어있다 (3). 또한, 20 mm 크기이하의작은폐병변에있어서도높은정확도를보이고있다 (2). 하지만고식적 CT를이용하는방법은시술을실시간으로모니터링할수없으며폐병변으로접근하는바늘의이동경로를반복적인촬영으로추적해야하므로시간이오래걸리고방사선노출이많아진다는단점이있다. 최근에는실시간으로바늘의위치를추적하며환자의호흡에도바로대처할수있는 CT fluoroscopy 를이용한생검이널리이용되고있다 (4). 고식적인 CT 유도하생검과비교하여시술시간이짧고환자의호흡에도실시간으로바늘위치를추적할수있다는장점이있지만여전히환자및시술자와연관된방사선피폭량이많고겐트리터널이작다는단점을극복하기어렵다 (5-7). 이러한고식적인 CT 또는 CT fluoroscopy 를이용한생검의단점을극복하고자, 인터벤션실에서 C-arm 콘빔 CT (conebeam CT; 이하 CBCT) 를이용한경피적흉부생검이시행되고있다. CBCT 를이용한경피적흉부생검은먼저투시조영영상을시행하여유도영상으로사용을하고 C-arm CBCT 로전환하여재구성영상을획득하고시술을시행하게된다. CT를이용한생검과달리좁은겐트리내에서시술을시행할필요가없고실시간으로투시조영영상과재구성 CT 영상을이용할수있어시술자에게유용한환경을제공하기때문에높은시술의정확도와능률을기대할수있다 (8-10). Jin 등 (11) 은 CBCT 유도하생검의정확도와민감도, 특이도를각각 98.4%, 97%, 100% 로보고하였으며 Hwang 등 (1) 은민감도, 특이도, 양성예측도, 음성예측도, 그리고정확도를각각 94%, 89%, 94%, 89%, 92% 로보고하였고특히, 1 cm 이하의작은폐결절에대해서는민감도, 특이도, 그리고정확도를각각 100%, 75%, 90% 로보고하였다. 현재까지 CBCT 를이용한흉부생검의장단점에대해서는잘알려져있으나투시조영하흉부생검에서 CBCT 를이용한흉부생검으로의전환에영향을주는요인들에대해서정량적인연구는보고되어있지않아, 본연구에서는이러한요인들에대해서후향적으로연구하였다. 대상과방법 대상환자 본연구는임상시험심의위원회 (Institutional Review Board) 의승인을통과하였으며모든자료는이미종료된진료과정에서 Table 1. Demographics and Image Characteristics between Patients Underwent Fluoroscopy Guided PTNB and Underwent Cone-Beam CT Guided PTNB Nonconverted Patients (n = 76) Converted Patients (n = 38) p-value Age 58.45 ± 1.94 57.89 ± 2.40 0.864 Sex 1.000 Male 48 (68.2) 24 (63.2) Female 28 (31.8) 14 (36.8) Date interval (days) 9.71 ± 1.41 11.29 ± 1.68 0.498 No. of biopsy 0.004 3 27 (35.5) 5 (13.2) < 3 49 (64.5) 33 (86.8) Surrounded consolidation 15 (19.7) 8 (21.1) 0.869 Abutting Vessel 1 (1.3) 7 (18.4) 0.001 Pleura 41 (53.9) 18 (47.4) 0.508 Cavitary lesion 11 (14.5) 5 (13.2) 0.849 Margin 0.337 Spiculated 18 (23.7) 13 (34.2) Smooth 34 (44.7) 12 (31.6) Irregular 24 (31.6) 13 (34.2) Location 1.000 Right upper 20 (26.3) 10 (26.3) Right lower 10 (13.2) 5 (13.2) Left upper 18 (23.7) 9 (23.7) Left lower 28 (36.8) 14 (36.8) Distribution 0.271 Proximal 4 (5.3) 4 (10.5) Middle 28 (36.8) 9 (23.7) Distal 44 (57.9) 25 (65.8) Emphysema 26 (34.2) 8 (21.1) 0.148 Patient position 0.083 Supine 29 (38.2) 21 (55.3) Prone 47 (61.8) 17 (44.7) Complication 0.020 Hemoptysis 6 (7.9) 10 (26.3) Pneumothorax 6 (7.9) 4 (10.5) Data in parentheses are percentages. Data interval means days between CT exam date and PTNB date. p value was calculated with the independent sample t test. p value was calculated with the Pearson χ 2 test. p value was calculated with the Fisher exact test. PTNB = percutaneous transthoracic needle biopsy jksronline.org 대한영상의학회지 2015;73(4):216-224 217
획득된영상자료의후향적인검토를통하여이루어진것으로대상환자의서면동의를얻는절차는생략하였다. 2011년 1월부터 2012 년 12 월까지본원인터벤션실에서투시조영하경피적흉부생검을시행받은 985 명중에서 CBCT 유도하경피적흉부생검으로전환된환자는총 84 명이었다. 이중 CBCT 로전환했음에도불구하고병변이보이지않은환자 5명과시술전흉부 CT 와비교하여크기가의미있게작아져명확하게양성병변으로생각되었던 5명, 병변내부에혈관을포함하고있어객혈의가능성이매우높아비디오흉강경을통한생검을권유했던 4명, 그리고협조가되지않았던환자 2명을제외하였다. 또한, 심장이나간의음영에겹쳐있어서 ( 각각 14 명, 13 명 ) 장기손상의위험성이높다고판단한환자 27명과간유리음영 (ground glass opacity) 의병변을가진환자 3명또한제외하였다. CBCT 로전환되지않고투시조영유도하경피적흉부생검만시행받은환 자들중에서무작위로 76 명을선발하였고, CBCT 로전환된 38 명의환자와함께최종적으로 114 명의환자가본연구에포함되었다. 시술시행직전에비교한흉부 CT 영상은본원에서촬영한조영증강흉부 CT와고해상전산화단층촬영 (high-resolution CT; 이하 HRCT)(Sensation 16 or SOMATOM Definition; Siemens Medical Solutions, Forchheim, Germany), 그리고조영증강영상과 HRCT 영상이섞여있는외부병원 CT였다. 본원조영증강흉부 CT로촬영한환자는 80명 (70.2%) 이었고본원 HRCT 로촬영한환자는 19 명 (16.7%) 이었으며외부병원 CT로촬영한환자는 15 명 (13.2%) 이었다. 모든환자는인터벤션실에서시술을시행받았으며 18-gauge 의자동화된생검총 (ACECUT, TSK laboratory, Tochigi, Japan) 을이용하였다. A B C D Fig. 1. A small pulmonary nodule in the right upper lobe of a 47-year-old woman with history of breast cancer. A. About 1 cm-sized well-marginated, small, round nodule in RUL is noted on the lung setting axial image of the HRCT. B. CT mean attenuation value is measured using free-drawing ROI on the mediastinal setting of axial image. C. The nodule was not detected on fluoroscopy performed with the patient in supine position. D. The operator accordingly performed cone-beam CT guided PTNB with careful adjustment of the needle. The result of PTNB indicated a metastatic adenocarcinoma. HRCT = high-resolution CT, PTNB = percutaneous transthoracic needle biopsy, ROI = region of interest, RUL = right upper lobe 218 대한영상의학회지 2015;73(4):216-224 jksronline.org
이강지외 총 114 명의환자중에남성은 72 명이었고여성은 42 명이었으며나이는 10~88 세 ( 평균, 60 세 ) 였다. 폐병변의특성을분석한 CT와 PTNB 시행까지의기간은 0~80일 ( 평균, 10일 ) 이었다. 투시조영유도하생검을시행한그룹에서남성은 48 명, 여성은 28 명이었으며나이는 10~81 세 ( 평균, 61 세 ) 였고, CBCT 유도하생검으로전환된그룹에서남성은 24 명, 여성은 14 명이었고나이는 16~88 세 ( 평균, 59.5세 ) 였다 (Table 1). 경피적흉부생검방법모든시술은 23 년의경피적흉부생검경력을가진인터벤션영상의학과전문의가시행하였다. 먼저, 경피적흉부생검을시행하기직전에촬영한흉부 CT에서폐병변과피부와의거리를측정하고가장가깝게접근할수있는방향에따라앙와위또는복와위로환자를인터벤션실침대에눕혔다. 그후, 이전에촬영 한흉부 CT를참고하여투시조영영상을통해폐병변을찾았다. 병변이투시조영영상에서잘보이고경계가잘지어지며심장이나간의음영에가려지지않는다면, 천자경로에해당하는피부에국소마취 (2% Lidocaine HCL, 명문제약, 화성, 한국 ) 후환자의호흡을고려하여 18 G의자동생검총으로 1~5회의조직생검을실시하였다. 모든환자는 CBCT (Syngo DynaCT, Siemens AG, Healthcare Sector, Forchheim, Germany) 기능을가지고있는투시조영장치 (AXIOM Artis dba; Siemens Medical Solutions, Forchheim, Germany) 를사용하였다. 만약에폐병변이투시조영영상에서뚜렷하게구분이되지않는경우즉시 CBCT 유도하생검으로전환하였으며, 먼저이전에촬영한 CT를참고하여병변이있을것으로추정되는위치의피부에방사선비투과성표지자를부착시키고 CBCT 를촬영하였다. 촬영된 CBCT 에서 A B C D Fig. 2. A solitary pulmonary mass suspicious for malignancy in the right lower lobe of a 72-year-old man, which was well-marginated, irregularshaped, and abutting the pleura. A. Antero-posterior diameter of the mass is measured to about 3.61 cm on the unenhanced axial image of the chest CT. B. CT mean attenuation value is subsequently measured using free-drawing ROI on the unenhanced axial image. C. Long-axis and short axis diameters are also measured on the coronal reconstructed image. D. Fluoroscopic image shows the mass with well-defined margin on the left side. The operator next performed fluoroscopy-guided PTNB with patient in prone position and careful adjustment of the needle; the result of PTNB indicated a squamous cell carcinoma. PTNB = percutaneous transthoracic needle biopsy, ROI = region of interest jksronline.org 대한영상의학회지 2015;73(4):216-224 219
Table 2. Pathologic Results of the Percutaneous Transthoracic Needle Biopsies 표지자의위치와병변의위치, 그리고환자의호흡을고려하여 피부에정확한천자부위표시를하였으며그후정확한위치에 국소마취후 18 G 자동절제총을이용하여생검을 1~5 회시행 하였다 (Fig. 1). 모든시술은생검직후환자의객혈여부와산소포화도, 그 리고혈압을주의깊게관찰하였으며기흉발생여부를확인하 기위해병실로가기전에흉부 X- 선영상을촬영하였으며, 약 일주일정도주의깊게추적관찰하였다. 영상분석방법 Biopsy Results Nonconverted Patients (n = 76) Converted Patients (n = 38) Total (n = 114) Malignancy Primary Adenocarcinoma 13 4 17 Squamous cell ca. 7 2 9 Small cell lung cancer 4 2 6 Sarcoma 0 1 1 Neurogenic tumor 1 0 1 AIS 1 0 1 Metastatic tumor 2 2 4 Benign CGI 20 8 28 Organizing pneumonia 10 4 14 NSCI 9 8 17 Fungus (aspergillosis) 2 1 3 Chondroidhamartoma 1 3 4 Failure Lung parenchyma 1 2 3 Necrotic tissue 1 0 1 Confirmed using VATs 4 1 5 Data in parentheses are percentages. Metastatic tumors from breast cancer, colorectal cancer, hepatocellular carcinoma, and diffuse large B cell lymphoma. Five cases was confirmed by using the VATs biopsy due to failure of PTNB. AIS = adenocarcinoma in situ (new name for BAC under the new IASLC), BAC = bronchoalveolar carcinoma, CGI = chronic granulomatous inflammation with/without necrosis, IASLC = International Association for the Study of Lung Cancer, NSCI = nonspecific chronic inflammation, PTNB = percutaneous transthoracic needle biopsy, VATs = video assisted thoracoscopy 투시조영유도하경피적흉부생검을시행한그룹과 CBCT 유도하생검으로전환된그룹과의영상특성을분석하기위해서 PTNB 직전에촬영한흉부 CT 를비교분석하였다. 흉부 CT 는 폐창기준 (window width: 1500, window level: -700) 으로하 여고형폐병변의단경, 장경, 전후길이를측정하고, 종격동창 기준 (window width: 400, window level: 70) 으로 CT 감쇠값을측정하였다. 분석에사용된흉부 CT의영상획득지표는다음과같았다. HRCT 는 120 kvp, 100 mas, 2 mm slices thickness, 3 mm reconstruction interval with a high spatial frequency algorithm, 조영증강흉부 CT는 100 kvp, 120 mas, 1.2~1.5 mm collimation, table pitch 1, 2 mm slice thickness, and 3 mm reconstruction increment. 모든 CT 영상은의료영상저장전송시스템을이용하였다 (PACS, m-view; Marotech, Seoul, Korea). 투시조영영상은환자의관상면으로영상을획득하기때문에흉부 CT에서의단층영상과의비교는맞지않아관상면으로재구성한영상을이용하여폐병변의가장긴길이 ( 장경 ) 와그와수직으로가장짧은길이 ( 단경 ) 를경력 3년의흉부영상판독경력을가진영상의학과의사가측정하였으며, 폐병변의면적이제일크게보이는단면에서관심영역 (region of interest) 을자유그리기모드로하여 CT 감쇠값을측정하였다. CT 감쇠값은평균값으로하였으며, 공동을가지고있는병변은내부의공동을제외하고주변의고형병변에대해서만감쇠값을측정하였다. 폐병변의위치도관상면을기준으로우상, 우하, 좌상, 그리고좌하로나누어분류하였다. 또한, 투시조영영상에서는조영제를사용하지않기때문에 CT 감쇠값을구하는데있어서반드시조영전영상을사용하였으며, 모든환자는 HRCT 또는조영전영상이포함된조영증강흉부 CT를촬영하였기때문에이러한이유로누락된환자군은없었다 (Fig. 2). 그밖에도, 영향을미칠수있는다른인자들을찾기위해폐병변의위치, 환자의체위, 흉막및혈관과의인접여부, 내부에공동포함여부, 생검횟수, 폐기종동반여부, 처음 CT 촬영일로부터 PTNB 를시행할때까지의기간등을측정하였다. 또한, 폐병변주변의경화병변동반여부와병변의경계를뾰족한경계, 매끈한경계, 불규칙적인경계로나누어분류하였다. 통계분석투시조영유도하경피적흉부생검만시행한그룹과 CBCT 유도하생검으로전환된그룹을비교하기위해서성별, 폐병변주변경화병변유무, 흉막및혈관인접유무, 병변내공동여부, 폐병변의경계, 위치, 생검횟수, 환자의체위와같은명목변수는 Pearson χ 2 test 와 Fisher exact test 를이용하였다. 환자의나이, PTNB 시행직전에촬영한흉부 CT와시술사이의기간, 폐병변의장경과단경, 전후길이와 CT 감쇠값과같은연속변수는 Student t test 를이용하여분석하였다. 또한, 로지스틱회귀분석 (logistic regression test) 을이용하여 CBCT 유도하생검으로의전환에영향을주는인자를분석하였 220 대한영상의학회지 2015;73(4):216-224 jksronline.org
이강지외 으며단변수분석에서 p값이 0.05 이하를보였던인자들에대해서후진제거법을사용하여분석하였다. 그밖에도 receiver operating characteristics ( 이하 ROC) curve 를이용하여 CBCT 유도하생검으로의전환에영향을주는인자들의곡선하면적 (area under the curve; 이하 AUC) 값을비교분석하였으며, 적절한기준값 (cut-off value) 에서의민감도와특이도를구하였다. 모든분석은 SPSS 20.0 for Windows (SPSS Inc., Chicago, IL, USA) 를이용하였다. 결과 경피적흉부생검을시행받은전체 114 명의환자중에서성공적인생검을시행받은환자는 105 명 (92.1%) 이었다. 생검결과상악성은 39 명 (37.1%) 이었고, 그중원발성악성폐종양은 35 명 (89.7%) 이고전이성폐종양은 4명 (10.3%) 이었다. 원발성악성폐종양중에서선암 (adenocarcinoma) 으로진단된환자는 17 명 (48.6%) 이고편평세포암 (squamous cell carcinoma) 으로진단된환자는 9명 (25.7%) 이었으며소세포암 (small cell lung cancer) 으로진단된환자는 6명 (17.1%) 이었다. 나머지는상피내선암 (adenocarcinoma in situ), 육종 (sarcoma), 신경종 (ganglioneuroblastoma) 으로진단받은사람이각각 1명씩이었다. 양성병변으로진단받은환자는 66 명 (62.9%) 이었으며, 이중에만성육아종성염증 (chronic granulomatous inflammation) 은 28 명 (42.4%) 이었고진균감염 (aspergillosis) 은 3명 (4.5%) 이었으며 기질화폐렴 (pneumonia with organization) 은 14 명 (21.2%) 이었다. 또한, 비특이적인만성염증 (nonspecific chronic inflammation) 으로진단된환자는 17명 (25.8%) 이었으며연골성과오종 (chondroidhamartoma) 과같은양성종양으로진단된환자는 4 명 (6%) 이었다 (Table 2). 성공적으로진단되지못한경우는 9명 (7.9%) 이었고정상폐조직만채취된경우가 3명 (33.3%), 괴사조직만채취된경우는 1명 (11.1%) 이었으며, 나머지 5명 (55.6%) 은비특이적염증으로진단되었으나악성종양이강력하게의심되어비디오흉강경을이용한생검을시행하였고, 수술후조직병리검사에서소세포암 2명 (40%), 편평세포암 1명 (20%), 선암 1명 (20%), 만성육아종성염증 1명 (20%) 으로확진되었다. PTNB 를시행받기직전에촬영한흉부단층촬영영상과시술시행간의평균기간은 10 일 (1~80 일 ) 로나타났으며두군간에통계적인차이는보이지않았다 (p = 0.498). 그리고폐병변주위경화병변소견과내부의공동포함여부, 병변의경계, 분포및폐기종, 환자의자세또한통계학적으로두군간에차이를보이지않았다. 하지만생검횟수의경우 CBCT 유도하생검을시행한경우에서 3번미만의적은횟수를보이는경우가의미있게많았다. CBCT 유도하경피적흉부생검으로전환된환자는 38 명이었으며 38 개의폐병변을가지고있었다. 38 개의폐병변에서평균단경은 1.60 ± 1.30 cm, 평균장경은 2.20 ± 1.45 cm, 평균전후길이는 1.91 ± 1.99 cm로나타났으며평균 CT 감쇠값 12 10 8 Fluoroscopy PTNB Cone-beam CT PTNB 150 100 6 50 4 0 2 0-50 Short-axis diameter Long-axis diameter Diameter of anterior to posterior Fluoroscopy guided PTNB Converted cone-beam CT guided PTNB A B Fig. 3. Box plots of predicting independent variables in conversion of fluoroscopy guided PTNB to cone-beam CT guided PTNB. A. Box plot comparing the short-axis diameter, long-axis diameter, and AP diameter of pulmonary lesion between the patients who underwent fluoroscopy-guided PTNB vs. cone-beam CT guided PTNB. B. Box plot showing CT attenuation value of pulmonary lesion of the above 2 groups., = outlier. AP = anterior to posterior, PTNB = percutaneous transthoracic needle biopsy jksronline.org 대한영상의학회지 2015;73(4):216-224 221
1.0 ROC curve 65.8%) 를보일때각각가장적절한민감도와특이도를나타내 었다 (Fig. 4). 0.8 고찰 Sensitivity 0.6 0.4 0.2 0.0 1-specificity Fig. 4. Receive operating characteristics curve (ROC curve). This graph showed statistically significant independent variables, short-axis diameter and CT attenuation value of the pulmonary lesion. AUC of these variables were 0.753 and 0.722, respectively. We set a cut-off value to 29.50 of CT attenuation that showed 65.8% of sensitivity and specificity, respectively; in addition, we set a cut-off value to 1.65 cm of short-axis diameter that showed 68.4% of sensitivity and 71.1% of specificity. AUC = area under the curve 은 18.32 ± 23.11 Hounsfield unit ( 이하 HU) 이었다. 투시조영 유도하경피적흉부생검만시행받은환자는 76 명이었으며 76 개의폐병변을가지고있었다. 76 개의폐병변에서평균단경은 2.70 ± 1.57 cm, 평균장경은 3.40 ± 1.92 cm, 평균전후길 이는 3.06 ± 1.81 cm 로나타났으며평균 CT 감쇠값은 35.67 ± 15.70 HU 였다. 이러한두군간에장경과단경, 전후길이, 그리고 CT 감쇠값은통계학적으로유의한차이를보였다 ( 각각 p = 0.001, p < 0.001, p = 0.003, p < 0.001)(Fig. 3). 이러한네개의독립변수들에대해서교란변수의영향을제 거하기위해로지스틱회귀분석을사용하였으며, 그결과 CT 감 쇠값 (odd ratio = 0.952) 과단경 (odd ratio = 0.618) 이작을수 록 CBCT 유도하생검으로전환이더잘일어나는것으로나타 났다 ( 각각 p = 0.002, p = 0.019). 기존단변수분석에유의하 게나타났던전후길이와장경은뚜렷한통계학적유의관계를 보이지는않았다. Short-axis diameter CT attenuation Reference line 0.0 0.2 0.4 0.6 0.8 1.0 통계학적으로비교적높은유의관계를보였던두변수들에 대해서 ROC curve 를이용하여비교분석을한결과 CT 감쇠값 (AUC = 0.722) 보다단경 (AUC = 0.753) 이좀더높은곡선하 면적값을보였다. 단경이 1.65 cm( 민감도 68.4%, 특이도 71.1%) 일때와 CT 감쇠값이 29.50 HU( 민감도 65.8%, 특이도 기존연구들을통해서, 투시조영유도하경피적흉부생검보다 CT를이용한생검이합병증을줄일수있어안전하고검사의정확도도높은우수한방법이라는점은많이알려져있다 (12-14). 고식적 CT를이용한흉부생검은공기로채워져있는폐실질의생검바늘이통과함에있어서그경로를최소화할수있고엽간열과혈관및기포를피하기쉬워작은폐결절이나폐문부에위치한폐병변에대해서생검이용이하다 (1). 그러나최근에는실시간모니터링이불가능하고겐트리를마음대로움직일수없는고식적인전산화단층촬영의단점을극복한 CBCT 유도하경피적흉부생검이널리이용되고있다 (15). 이러한 CBCT 를이용하면기존의투시조영을이용한생검과마찬가지로실시간으로병변을관찰하면서도, CT를이용한생검에서와마찬가지로안전하고정확한생검을시행하는것이가능하기때문에시간이절약되고환자의안정성측면에서도더효율적이다. 고형폐병변의크기가클수록진단적정확도는증가하고, 반대로크기가작을수록정확도는감소하기때문에 (16) 진단적정확도를높이기위해서는작은병변의경우, CBCT 를이용한흉부생검을통해정확도를올릴수있다. 따라서투시조영유도하생검에서보이는관상면을기준으로, 폐병변의단경, 장경, 그리고단층면을기준으로폐병변의전후길이를 CBCT 유도하생검으로의전환에영향을주는인자로설정하였다. CBCT 로의전환에높은영향을끼칠것으로생각했던전후길이는두군간에통계학적인차이를보이지않았으며 CT 감쇠값은높은연관성을보였다. 장경만크게관찰되는폐병변의경우는단경의영향을크게받게되어폐병변이선형부터원형까지다양한모양을보이게되기때문에통계적으로차이를보이지못했을것으로생각되며, 단경의경우는크면클수록장경도함께증가하게되므로병변을더잘보이게하는것으로생각하였다. 전후길이의경우는인체의조직밀도로는 X-선투과에큰영향을주지않아전환에유의한결과를주지못했다고생각된다. 본연구에서시술직후에객혈이발생한환자는 16 명 (14%) 이었으며, 기존연구에서보고되었던 26% 보다는낮은결과를보였다 (17). 하지만시술직후에객혈을보이지는않았으나다음날객혈이발생하고그양이증가하여기관지동맥색전술을시행받은환자가 1명있었다. 기흉이발생한환자는총 10 명 (8.8%) 이었으며이중에 2명의환자에서다량의기흉이발생하였고흉관삽관을시행하였다. 그밖에다른합병증을보인환자는없었다. 222 대한영상의학회지 2015;73(4):216-224 jksronline.org
이강지외 본연구에는몇가지한계점이있다. 첫째로, CBCT 를이용한흉부생검을시행한군의숫자가적고투시조영을이용한경피적흉부생검군을무작위로추출하였기때문에표본선정편파 (selection bias) 를피하기어렵다. 둘째로, 고형폐병변을영상분석하는데있어서단경, 장경및전후길이와같은이차원적인방법을사용하였기때문에삼차원적인분석방법에비해서오류가있을수있다. 셋째로, 시술을시행할때간이나심장에가려져서어쩔수없이 CBCT 를이용했던환자군은처음부터연구에서제외하였으나, 늑골과같은골격구조물로가려지는작은폐병변은제외하지않아이로인한오류가있을수있다. 환자호흡조절을통해서도노출되지않는작은폐병변은 CBCT 로전환하여비스듬하게바늘을삽입하여생검을진행하였으나실제 CT 영상분석을할때이런경우를고려하지않았기때문에결과가과장되었을가능성을배제할수없다. 넷째로, 시술자의경험이나선호도및장비성능의차이에따른오차를고려하지않았다. 큰고형폐병변인경우에도더좋은조직표본을얻기위해서특정부위에서생검을하거나환자의자세나큰혈관을피하기위해서 CBCT 를이용해서생검을시도할수있기때문에이에따른오차가발생할수있다. 결론적으로투시조영유도하경피적흉부생검을시행할때, 환자폐병변의 CT 감쇠값과단경이작을수록 CBCT 유도하생검으로의전환이더잘일어나게되며, 폐병변의장경과전후길이는전환에영향을주지않았다. REFERENCES 1. Hwang HS, Chung MJ, Lee JW, Shin SW, Lee KS. C-arm cone-beam CT-guided percutaneous transthoracic lung biopsy: usefulness in evaluation of small pulmonary nodules. AJR Am J Roentgenol 2010;195:W400-W407 2. Laurent F, Latrabe V, Vergier B, Montaudon M, Vernejoux JM, Dubrez J. CT-guided transthoracic needle biopsy of pulmonary nodules smaller than 20 mm: results with an automated 20-gauge coaxial cutting needle. Clin Radiol 2000;55:281-287 3. Westcott JL. Percutaneous transthoracic needle biopsy. Radiology 1988;169:593-601 4. Hur J, Lee HJ, Nam JE, Kim YJ, Kim TH, Choe KO, et al. Diagnostic accuracy of CT fluoroscopy-guided needle aspiration biopsy of ground-glass opacity pulmonary lesions. AJR Am J Roentgenol 2009;192:629-634 5. Froelich JJ, Ishaque N, Regn J, Saar B, Walthers EM, Klose KJ. Guidance of percutaneous pulmonary biopsies with real-time CT fluoroscopy. Eur J Radiol 2002;42:74-79 6. Daly B, Templeton PA. Real-time CT fluoroscopy: evolution of an interventional tool. Radiology 1999;211:309-315 7. Kim GR, Hur J, Lee SM, Lee HJ, Hong YJ, Nam JE, et al. CT fluoroscopy-guided lung biopsy versus conventional CTguided lung biopsy: a prospective controlled study to assess radiation doses and diagnostic performance. Eur Radiol 2011;21:232-239 8. Choi JW, Park CM, Goo JM, Park YK, Sung W, Lee HJ, et al. C-arm cone-beam CT-guided percutaneous transthoracic needle biopsy of small ( 20 mm) lung nodules: diagnostic accuracy and complications in 161 patients. AJR Am J Roentgenol 2012;199:W322-W330 9. Choo JY, Park CM, Lee NK, Lee SM, Lee HJ, Goo JM. Percutaneous transthoracic needle biopsy of small ( 1 cm) lung nodules under C-arm cone-beam CT virtual navigation guidance. Eur Radiol 2013;23:712-719 10. Lee WJ, Chong S, Seo JS, Shim HJ. Transthoracic fine-needle aspiration biopsy of the lungs using a C-arm conebeam CT system: diagnostic accuracy and post-procedural complications. Br J Radiol 2012;85:e217-e222 11. Jin KN, Park CM, Goo JM, Lee HJ, Lee Y, Kim JI, et al. Initial experience of percutaneous transthoracic needle biopsy of lung nodules using C-arm cone-beam CT systems. Eur Radiol 2010;20:2108-2115 12. Ohno Y, Hatabu H, Takenaka D, Higashino T, Watanabe H, Ohbayashi C, et al. CT-guided transthoracic needle aspiration biopsy of small (< or = 20 mm) solitary pulmonary nodules. AJR Am J Roentgenol 2003;180:1665-1669 13. Geraghty PR, Kee ST, McFarlane G, Razavi MK, Sze DY, Dake MD. CT-guided transthoracic needle aspiration biopsy of pulmonary nodules: needle size and pneumothorax rate. Radiology 2003;229:475-481 14. Lima CD, Nunes RA, Saito EH, Higa C, Cardona ZJ, Santos DB. Results and complications of CT-guided transthoracic fine-needle aspiration biopsy of pulmonary lesions. J Bras Pneumol 2011;37:209-216 15. Lee SM, Park CM, Lee KH, Bahn YE, Kim JI, Goo JM. C-arm cone-beam CT-guided percutaneous transthoracic needle biopsy of lung nodules: clinical experience in 1108 patients. Radiology 2014;271:291-300 jksronline.org 대한영상의학회지 2015;73(4):216-224 223
16. Li H, Boiselle PM, Shepard JO, Trotman-Dickenson B, McLoud TC. Diagnostic accuracy and safety of CT-guided percutaneous needle aspiration biopsy of the lung: comparison of small and large pulmonary nodules. AJR Am J Roentgenol 1996;167:105-109 17. Yeow KM, See LC, Lui KW, Lin MC, Tsao TC, Ng KF, et al. Risk factors for pneumothorax and bleeding after CTguided percutaneous coaxial cutting needle biopsy of lung lesions. J Vasc Interv Radiol 2001;12:1305-1312 경피적흉부생검시투시조영유도하생검에서 Cone-Beam CT 유도하생검으로전환되는데영향을미치는요인 이강지 1 한영민 1,2,3 진공용 1,2 송지수 1 목적 : 경피적흉부생검을시행할때, 투시조영유도하생검에서콘빔 CT 유도하생검으로시술방법을전환하는데영향을미치는요인을알아보고자하였다. 대상과방법 : 본연구는후향적으로진행되었으며, 2011년 1월부터 2012 년 12 월까지콘빔 CT를이용한경피적흉부생검을시행받은환자 38 명과투시조영유도하경피적흉부생검을시행받은환자중에서콘빔 CT 유도하경피적흉부생검군과비슷한연령과성별, 폐병변위치를보이는 76 명의환자를대상으로하였다. 투시조영유도하흉부생검에서콘빔 CT를이용한흉부생검으로의전환에영향을미치는예측인자로서고형폐병변의장경, 단경, 전후길이, 그리고 CT 감쇠값을 Pearson χ 2 test 와 Fisher exact test 및독립표본 t test 를이용하여분석하였다. 또한 receiver operating characteristic ( 이하 ROC) curve 분석을통해콘빔 CT로의전환을결정하는예측값을찾고자하였다. 결과 : 투시조영유도하경피적흉부생검을시행받은환자들의폐병변의평균단경은 2.70 ± 1.57 cm, 평균장경은 3.40 ± 1.92 cm, 평균전후길이는 3.06 ± 1.81 cm였으며, 평균 CT 감쇠값은 35.67 ± 15.70 Hounsfield unit ( 이하 HU) 이었다. 콘빔 CT 유도하경피적흉부생검으로전환된환자들의폐병변의평균단경은 1.60 ± 1.30 cm, 평균장경은 2.20 ± 1.45 cm, 평균전후길이는 1.91 ± 1.99 cm였으며, 평균 CT 감쇠값은 18.32 ± 23.11 HU 였다. 이러한두군간에고형폐병변의단경과장경, 전후길이, 그리고 CT 감쇠값은통계학적으로유의한차이를보였다 ( 각각 p = 0.001, p <0.001, p = 0.003, p < 0.001). CT 감쇠값과단경의교차비는각각 0.952, 0.618 로나타났다. ROC curve 에서전환에기준이되는적절한단경은 1.65 cm( 민감도 68.4%, 특이도 71.1%) 였으며, CT 감쇠값은 29.5( 민감도 65.8%, 특이도 65.8%) 였다. 결론 : 고형폐병변의 CT 감쇠값과단경이작을수록콘빔 CT 유도하생검으로의전환이더잘일어난다. 전북대학교의학전문대학원전북대학교병원 1 영상의학과, 2 임상의학연구소, 3 심혈관연구소 224 대한영상의학회지 2015;73(4):216-224 jksronline.org