J Korean Soc Radiol JKSR Journal of the Korean Society of Radiology 1738-2637 2288-2928 The Korean Society of Radiology 10.3348/jksr.2015.73.4.216 Chest Radiology Predicting Factors for Conversion from Fluoroscopy Guided Percutaneous Transthoracic Needle Biopsy to Cone-Beam CT Guided Percutaneous Transthoracic Needle Biopsy Lee Kang Ji MD 1 Han Young Min MD 1 2 3 Jin Gong Yong MD 1 2 Song Ji Soo MD 1 Department of Radiology, Chonbuk National University Hospital and Medical School, Jeonju, Korea. Research Institute of Clinical Medicine, Chonbuk National University Hospital and Medical School, Jeonju, Korea. Institute of Cardiovascular Research, Chonbuk National University Hospital and Medical School, Jeonju, Korea. 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, ymhan@jbnu.ac.kr 10 2015 25 09 2015 73 4 216 224 17 02 2015 04 08 2015 07 08 2015 Copyright © 2015 The Korean Society of Radiology 2015 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. 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 cone-beam CT guided PTNB. Pearson χ2 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.

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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 meta-static adenocarcinoma.

HRCT = high-resolution CT, PTNB = percutaneous transthoracic needle biopsy, ROI = region of interest, RUL = right upper lobe

 A solitary pulmonary mass suspicious for malignancy in the right lower lobe of a 72-year-old man, which was well-marginated, irregular-shaped, 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

 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

 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

 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 χ2 test.

§p value was calculated with the Fisher exact test.

PTNB = percutaneous transthoracic needle biopsy

 Pathologic Results of the Percutaneous Transthoracic Needle Biopsies
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