Dynamic CT Findings of Pulmonary Hamartoma: a Comparison with Histopathologic Findings1 폐과오종의 역동적 전산화단층촬영 소견: 조직병리학적 소견과의 비교1

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Original Article pISSN 1738-2637 / eISSN 2288-2928 J Korean Soc Radiol 2013;69(6):449-455 http://dx.doi.org/10.3348/jksr.2013.69.6.449

Dynamic CT Findings of Pulmonary Hamartoma: A Comparison with Histopathologic Findings1 폐과오종의 역동적 전산화단층촬영 소견: 조직병리학적 소견과의 비교1

Wanglae Cho, MD1, Yeon Joo Jeong, MD1, Chang Hun Lee, MD2, Ji Won Lee, MD1, Kun-Il Kim, MD3, Jeong A Yeom, MD3, Yeong Dae Kim, MD4 Departments of 1Radiology, 2Pathology, 4Thoracic and Cardiovascular Surgery, Pusan National University Hospital, Pusan National University School of Medicine and Medical Research Institute, Busan, Korea 3Department of Radiology, Pusan National University Yangsan Hospital, Pusan National University School of Medicine and Medical Research Institute, Yangsan, Korea

Purpose: To describe the dynamic CT findings of pulmonary hamartoma and to Index terms compare these findings with histopathologic findings. Lung Neoplasm Materials and Methods: The Institutional Review Board approved this retrospec- Hamartoma tive study and the requirement for patient informed consent was waived. The he- Multidetector Computed Tomography modynamic CT features of 11 patients (M : F = 6 : 5; mean age, 53.6 years) with Pathology pathologically proven pulmonary hamartoma were evaluated. All 11 patients underwent enhanced dynamic CT using a helical technique. A series of images were obtained throughout each nodule with 2.5-mm collimation at 0, 30, 60, 90 and 120 seconds and at 4, 5 and 15 minutes after an intravenous injection of contrast medium. Extents and patterns of enhancement were correlated with histologic tumor components. Results: All 11 tumors showed persistent enhancement with variable degrees of net enhancement [mean tumor peak enhancement, 48.6 ± 19.0 Hounsfield unit (HU); mean tumor net enhancement, 31.9 ± 11.8 HU] and thick capsular and septal en- Received July 17, 2013; Accepted September 13, 2013 hancement. Histologically, all 11 tumors were composed of mature cartilage and Corresponding author: Yeon Joo Jeong, MD loose mesenchymal tissue. A significant positive correlation was found between the Department of Radiology, Pusan National University Hospital, Pusan National University School of Medicine, net enhancement values and loose connective tissue component percentages (r = 179 Gudeok-ro, Seo-gu, Busan 602-739, Korea. 0.749, p = 0.008); further, a negative correlation was found between the net en- Tel. 82-51-240-7354 Fax. 82-51-244-7534 hancement values and cartilaginous component percentages (r = -0.813, p = 0.002). E-mail: [email protected] Conclusion: On dynamic CT, hamartoma exhibited persistent enhancement without This is an Open Access article distributed under the terms washout as well as thick capsular and septal enhancements. Net enhancement values of the Creative Commons Attribution Non-Commercial were found to be positively correlated with the proportion of the loose connective tis- License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distri- sue component. Thick capsular and septal enhancements were attributed histopatho- bution, and reproduction in any medium, provided the logically to loose connective tissue, separating tumors into cartilaginous lobules. original work is properly cited.

INTRODUCTION most common type of pulmonary nodule, and they account for approximately 5% of solitary pulmonary tumors and 75% of be- Pulmonary hamartomas are benign lesions composed of an nign lung tumors (3-5). abnormal mixture of epithelial and mesenchymal elements, On CT, pulmonary hamartoma usually appears as a smooth such as cartilage, fat, fibromyxoid tissue, smooth muscle and or slightly lobulated, peripheral solitary pulmonary nodule bone (1, 2). These benign lesions used to be considered develop- (SPN) (5). The presence of fat or popcorn-like calcifications may mental abnormalities, but now they are considered benign mes- enable a confident diagnosis; yet, these findings are only visual- enchymal neoplasms. Pulmonary hamartomas are the third ized by CT in approximately 30% of cases (5, 6). In many cases,

Copyrights © 2013 The Korean Society of Radiology 449 Dynamic CT Findings of Pulmonary Hamartoma the lack of fat or calcification makes it difficult to reach a diag- calcified SPN, ranging from 7 mm to 30 mm detected on the nosis by CT and therefore, invasive techniques, such as percuta- chest radiograph or non-enhanced chest CT scans. Written in- neous needle aspiration, biopsy or surgery, are required to con- formed consent regarding the dynamic CT protocol was ob- firm diagnosis. tained from all patients. Before the IV injection of contrast mate- Previous studies have shown that dynamic CT could usefully rial, an unenhanced series of images were obtained throughout differentiate benign and malignant nodules; moreover, several each nodule, over 30 mm of the z-axis with 2.5-mm collimation benign nodules have characteristic hemodynamic features (7). at 120 kVp and 90 mA. Thereafter, an additional series of images However, although the CT enhancement pattern of pulmonary were obtained at 30, 60, 90 and 120 seconds and at 4, 5 and 15 hamartoma using a single helical CT has been reported (8), to minutes intervals after commencing the contrast injection using the best of our knowledge, the diagnostic utility of a dynamic the same imaging parameters used for the initial pre-enhance- multidetector CT (MDCT) for the diagnosis of pulmonary ham- ment series. An amount of 1.5 mL/kg (body weight) of Iomeron artoma has not been previously described in the English litera- 300 (Iomeprol, 300 mg iodine/mL; Bracco; Milan, Italy) was in- ture. Accordingly, the purpose of this study was to describe the jected at an infusion rate of 3 mL/s using a power injector (MCT dynamic CT findings of pulmonary hamartoma presenting as a Plus; Medrad; Pittsburgh, PA, USA). Immediately after dynamic SPN as well as to correlate these findings with the histopatho- imaging at 120 seconds, helical CT scans (125 mA, 120 kVp, logic findings. 5-mm collimation) were obtained from the lower neck to the level of the middle portion of both kidneys. The estimated total MATERIALS AND METHODS lung radiation dose ranged from 4.1 to 6.8 mSv [mean ± standard deviation (SD), 4.4 ± 1.7 mSv]. The image data were refor- Patients matted with a section thickness of 2.5 mm for transaxial images, This retrospective study was approved by our Institutional Re- and the reconstructed images obtained were interfaced directly view Board. We evaluated the morphologic and hemodynamic with picture archiving and a communication system (M-view; CT features of 11 patients (M : F = 6 : 5; mean age, 53.6 years; age INFINITT Healthcare, Seoul, Korea), which displayed the im- range, 33-69 years) with surgical biopsy-proven pulmonary ham- ages on two monitors (2048 × 2560 image matrices, 10-bit view- artoma who registered at our institute between March 2004 and able gray scale, and 145.9-ft-Lambert luminescence). Both me- March 2012. These patients underwent wedge resection n( = 9) diastinal [width, 400 Hounsfield unit (HU); level, 25 HU] and and segmentectomy (n = 2). In this study, we included only sur- lung (width, 1500 HU; level, -700 HU) window images were gical biopsy-proven pulmonary hamartoma in order to correlate viewed on these monitors. its dynamic CT findings with the histopathologic findings. Nine of the 11 patients were asymptomatic. In these patients, Image Interpretation tumors were identified incidentally as SPNs on the chest radio- Two chest radiologists, one with 10 and the other with 2 years graphs obtained during routine medical examinations. The oth- of chest CT experience, independently evaluated the images. er two patients had nonspecific symptoms, such as a mild cough The morphologic features of nodules determined by analyz- (n = 1) and pleuritic chest pain (n = 1). ing the unenhanced thin-section CT scans included size, shape, margin characteristics and the presence of calcification and fat. Image Analysis Nodule size was defined as the long-axis diameter on lung-win- All 11 patients underwent contrast-enhanced helical CT us- dow images. Nodular shapes were classified as round, ovoid or ing a 64-dual energy MDCT (Discovery HD 750; GE Health- rectangular, and margins were classified as smooth, lobulated or care, Milwaukee, WI, USA) or a four-row detector (LightSpeed spiculated. Calcification was classified as stippled, central nodu- QX/i; GE Healthcare, Milwaukee, WI, USA) scanner. In our in- lar, laminated or diffuse. Final decisions regarding the morpho- stitution, dynamic CT scans were routinely preformed with the logic features were reached by a consensus. approval of our institutional review board in patients with non- On the dynamic studies, we measured the nodule attenuation

450 J Korean Soc Radiol 2013;69(6):449-455 jksronline.org Wanglae Cho, et al values in the same regions on the selected images for each series lage, loose connective tissue, fat, calcification and slit-like clefts of images. A circular region of interest (range: 16-200 mm², mean: lined with epithelium, were evaluated. The proportions of carti- 60.63 mm²) was placed over the nodule and was made as large laginous, loose connective tissue and fat components in whole as possible. Two radiologists independently measured the atten- tumors were automatically quantified with an image analyzer in uation values, and the two measurements obtained for each nod- sections that included the largest plane of tumor tissue. ule at each imaging phase by the two radiologists were averaged. Several dynamic characteristics of tumor enhancement were cal- Statistical Analysis culated, that is; baseline attenuation (AVBase), peak enhancement Statistical analysis was performed using SPSS software (SPSS (PE = attenuation at maximum), net enhancement (NE = PE - for Windows, version 11.0, SPSS Inc., Chicago, IL, USA). The re-

AVBase), attenuation value at 15-minutes (AVDelay) and washout sults were expressed as mean ± SD for continuous variables. value (attenuation difference between PE and AVDelay, WV = PE - Spearman correlation coefficients were used to evaluate the cor-

AVDelay). relation between the extents of CT enhancement and also deter- Capsular and septal enhancement of pulmonary hamartoma mined the tumor component percentages. Statistical significance has been previously reported (8) and therefore, we evaluated the was accepted for p values < 0.05. enhancement patterns (homogeneous vs. capsular and septal) and sought to determine the imaging phase that best visualized RESULTS such enhancement patterns. The mean tumor long-axis diameter was 14.8 mm (SD, ± 5.8; Pathologic Comparisons range, 10-30 mm). Seven (64%) tumors were round and 4 (36%) The intervals between pathologic evaluations and chest CT were ovoid. Six (55%) tumors had smooth margins and 5 (45%) scans ranged from 10 to 60 days (median, 33 days). A pulmo- had lobulated margins. Only one tumor (9%) contained an in- nary pathologist (unaware of CT finding) with 19 years of expe- tratumoral stippled calcification. Three nodules (27%) had focal rience in lung pathology evaluated all specimens. With routine areas of negative CT attenuation values, suggesting an intratu- light microscopy and hematoxylin and eosin (H&E) staining, moral fat component. the compositions of tumor components, that is, mature carti- An enhanced dynamic CT study was feasible for all 11 pa-

Table 1. Dynamic CT and Histopathologic Characteristics of the 11 Pulmonary Hamartoma Dynamic CT Characteristics Histopathologic Characteristics Patient Connective No. AVBase (HU) PE (HU) AVDelay (HU) NE (HU) WV (HU) Cartilage (%) Fat (%) Tissue (%) 1 10 49 49 39 0 54.97 40.52 4.51 2 24 67 67 43 0 53.21 46.79 0 3 -7 25 25 32 0 60.49 37.14 2.37 4 13 64 64 51 0 46.67 47.31 6.02 5 32 54 54 22 0 76.60 23.40 0 6 54 62 62 8 0 86.36 13.64 0 7 14 53 53 39 0 32.58 51.46 15.96 8 -11 13 13 23 0 68.22 31.78 0 9 41 73 73 32 0 52.07 47.93 0 10 -10 29 29 36 0 36.54 52.90 10.55 11 20 46 46 26 0 67.56 32.44 0 Mean 16.4 48.6 48.6 31.9 0 57.8 38.7 3.58 SD 20.9 19.0 19.0 11.8 0 16.3 12.4 5.36

Note.-AVBase = attenuation value at baseline, AVDelay = attenuation value at 15 minutes after commencing injection, HU = Hounsfield unit, NE = net enhancement (PE - AVBase), PE = peak enhancement, SD = standard deviation, WV = washout value (PE - AVDelay), % = percentages of tissue components in whole tumors jksronline.org J Korean Soc Radiol 2013;69(6):449-455 451 Dynamic CT Findings of Pulmonary Hamartoma tients. Dynamic CT and histopathologic characteristics of 11 without washout and with a variable degrees of enhancement cases are summarized in Table 1. For the enhanced dynamic CT (range, 8-51 HU) (Figs. 1, 2). studies, the mean AVBase was 16.4 HU (SD, ± 20.9; range, -11- All nodules showed a thick capsular and septal enhancement 54), mean PE value was 48.6 ± 19.0 HU and mean NE value was at different imaging phases [at 60 seconds n( = 1), at 90 seconds 31.9 ± 11.8 HU. All nodules showed a persistent enhancement (n = 5), at 4 minutes (n = 3), at 5 minutes (n = 2)] (Figs. 1, 2).

A B C

D E Fig. 1. A 39-year-old man (patient 2) with pulmonary hamartoma with persistent (PE, 67 HU; NE, 43 HU) and septal enhancement on dynamic CT. A. Targeted view of a transverse lung window CT scan shows a 13-mm-sized nodule with a lobulated margin in the left upper lobe. B. Targeted view of a transverse mediastinal window CT scan 90 seconds after contrast injection shows peripheral and septal enhancement. C. Sagittal section of an excised specimen in the same patient shows that the tumor consisted of glistening nodules of cartilage separated by clefts. D. Low-magnification photomicrograph shows multiple lobules of mature cartilage intersected by abundant loose connective tissue containing fat and smooth muscle and clefts lined by respiratory epithelium. E. Schema of tumor components, the percentages of cartilaginous component (areas within blue lines) and loose connective tissue components were 53.21% and 46.79%, respectively. Note.-HU = Hounsfield unit, NE = net enhancement, PE = peak enhancement

A B C Fig. 2. A 54-year-old man (patient 6) with pulmonary hamartoma with persistent (PE, 62 HU; NE, 8 HU) and septal enhancement on dynamic CT. A. Targeted view of a transverse mediastinal window CT scan 5 minutes after contrast injection shows peripheral and septal enhancement. B. Low-magnification photomicrograph shows multiple lobules of mature cartilage with intersecting parse loose connective. C. Schema of tumor components, the percentages of cartilaginous component (areas within blue lines) and of loose connective tissue components were 86.36% and 13.64%, respectively. Note.-HU = Hounsfield unit, NE = net enhancement, PE = peak enhancement

452 J Korean Soc Radiol 2013;69(6):449-455 jksronline.org Wanglae Cho, et al

All 11 tumors were composed of mature cartilage and loose mors into cartilaginous lobules (less enhancement portion). mesenchymal tissue, which is typical of pulmonary hamartoma. The persistent enhancement pattern without washout is ob- Five tumors had fat components ranging from 2.37% to 15.96%. served for many benign nodules and may be related to the amount The percentages of tumor components are summarized in Table and degree of fibrosis (9-11). Delayed uptake of contrast medi- 1. Fig. 3 shows the relationship between NE values and patho- um may be attributed to contrast redistribution, that is, in the logic results. A significant positive correlation was found be- early phase, well-vascularized tumor cell zones show contrast tween the NE values and loose connective tissue component enhancement; however, after contrast medium has moved into percentages (r = 0.749, p = 0.008), and a negative correlation the abundant fibrous tissue with scant blood supply during the was found between the NE values and cartilaginous component late phase, it remains in this tissue, and thus, shows an enhance- percentages (r = -0.813, p = 0.002). A comparison of the en- ment of fibrotic portion of the nodule for a long time without hancement patterns and histopathologic findings revealed that washout. Pathologically, hamartomas of the lung are composed contrast-enhanced septa corresponded to loose connective tis- of an abnormal mixture of epithelial and mesenchymal elements, sue, separating tumors into cartilaginous lobules. Peripheral such as cartilage, fat, fibromyxoid tissue, smooth muscle and contrast enhancement was found to correspond to loose con- bone. Therefore, persistent enhancement without washout on nective tissue, and not to true capsules. dynamic CT scans may be related to abundant fibrous stroma. However, malignant nodules, such as adenocarcinoma, may DISCUSSION show persistent enhancement without washout on dynamic CT (7). Therefore, dynamic enhancement patterns do not allow the The important observations in this study are summarized as possibility of lung cancer to be excluded. Potente et al. (8) re- follows: pulmonary hamartoma exhibited a persistent enhance- ported septal enhancement in pulmonary hamartoma and cor- ment with a variable degree of net enhancement without wash- related the enhancement patterns with pathologic findings. out and thick capsular and septal enhancements on dynamic CT. Twenty-four (80%) of 30 pulmonary hamartomas showed sep- NE values were found to be positively correlated with loose con- tal enhancement, separating tumors into less dense lobules on nective tissue component percentages and thick capsular and dynamic CT images. In the present study, thick septal and cap- septal enhancement was attributed histopathologically to the sular enhancement was observed in all tumors. The discrepancy loose connective tissue (contrast enhanced septa), separating tu- between percentages observed in the two studies may be related

51.00 51.00 43.00 43.00 39.00 39.00 36.00 36.00

32.00 32.00 26.00 26.00

23.00 23.00 Net enhancement (HU) Net enhancement (HU) 22.00 22.00 8.00 8.00

10.00 20.00 30.00 40.00 50.00 60.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 Connective tissue component (%) Cartilage component (%) A B Fig. 3. Correlation between dynamic CT NE values and pathologic results. A. The correlation between NE values and loose connective tissue component percentages (r = 0.749, p = 0.008). B. The correlation between NE values and cartilage component percentages (r = -0.813, p = 0.002). Note.-HU = Hounsfield unit, NE = net enhancement jksronline.org J Korean Soc Radiol 2013;69(6):449-455 453 Dynamic CT Findings of Pulmonary Hamartoma to the CT units and dynamic CT protocols used. Potente et al. tion, such as popcorn-like calcification or visible fat component, (8) used single helical CT scans and obtained dynamic CT im- due to relatively high radiation doses. Although we used scan- ages at 1-minute intervals for up to 3 minutes. However, in the ning parameters with lower mA, the estimated total lung dose present study, we used multidetector CT scans and obtained dy- was 4.4 mSv, which is slightly higher than that of standard namic CT images at detailed intervals for up to 15 minutes. A MDCT. A low-dose technique that presented a lower radiation pathologic comparison study showed that contrast-enhanced risk or truncation of the dynamic CT technique would have septa and capsule corresponded to loose connective tissues, sep- been more advisable. arating tumors into cartilaginous lobules. Park et al. (12) also In conclusion, hamartoma was found to exhibit persistent en- evaluated cleft-like or septal structures of pulmonary hamarto- hancement without wash-out and thick capsular and septal en- ma using magnetic resonance imaging (MRI), and found that hancement by dynamic CT. NE values were found to be positively all six tumors had cleft-like structures, which were particularly correlated with loose connective tissue component proportions. evident on the T2-weighted images. Furthermore, pathological- Thick capsular and septal enhancement was attributed histopath- ly, these structures were found to represent variable mesenchy- ologically to loose connective tissue, which separates tumors into mal tissue components arrayed along the respiratory epithelial cartilaginous lobules. A follow-up dynamic CT showing persis- cells lining the cleft; they show richer vascularity compared to tent enhancement with thick capsular and septal enhancement the main portion of pulmonary hamartoma. could be helpful in the diagnosis of an ambiguous case of ham- Previous studies have reported several radiologic features of artoma on the initial CT. hamartoma (1, 5, 8, 13). Characteristic CT findings of hamartomas were found to be a lesion of 2.5 cm in diameter or smaller REFERENCES with a smooth margin and focal areas of fat or areas of calcification (5). The diagnosis of pulmonary hamartoma by CT is heav- 1. Gjevre JA, Myers JL, Prakash UB. Pulmonary hamartomas. ily dependent on the presence of detectable fat or popcorn-like Mayo Clin Proc 1996;71:14-20 calcifications within lesions. However, many cases fail to exhibit 2. Saqi A, Shaham D, Scognamiglio T, Murray MP, Henschke a macroscopic fat component. In the present study, intratumoral CI, Yankelevitz D, et al. Incidence and cytological features fat was observed in only 27% and calcification in only 9% on of pulmonary hamartomas indeterminate on CT scan. Cy- CT. In these cases, the hemodynamic features of tumors by dy- topathology 2008;19:185-191 namic CT can aid the diagnosis. MRI with the chemical-shift 3. Seda G, Amundson D, Lin MY. Predominant cartilaginous technique may also be useful for detecting intracellular lipids in hamartoma: an unusual variant of chondromatous ham- pulmonary hamartomas without definite fat density by CT (14). artoma. South Med J 2010;103:169-171 Although lung MRI has made important progress with respect 4. Swensen SJ, Brown LR, Colby TV, Weaver AL. Pulmonary to speed and image quality in recent years, the technique still nodules: CT evaluation of enhancement with iodinated has several limitations, such as high susceptibility differences contrast material. Radiology 1995;194:393-398 between air spaces and pulmonary interstitium and the pres- 5. Siegelman SS, Khouri NF, Scott WW Jr, Leo FP, Hamper ence of respiratory and cardiac motion artifacts, which make it UM, Fishman EK, et al. Pulmonary hamartoma: CT find- unsuitable for routine clinical use, particularly for the evaluation ings. Radiology 1986;160:313-317 of small SPNs. 6. Whyte RI, Donington JS. Hamartomas of the lung. Semin Our study has several limitations. First, due to the rarity of Thorac Cardiovasc Surg 2003;15:301-304 pulmonary hamartoma, the number of cases recruited was too 7. Jeong YJ, Lee KS, Jeong SY, Chung MJ, Shim SS, Kim H, et small to prove the power of statistical analysis. Second, the study al. Solitary pulmonary nodule: characterization with com- suffers from selection bias because we only included histopatho- bined wash-in and washout features at dynamic multi- logically proven cases. In addition, dynamic CT scans were not detector row CT. Radiology 2005;237:675-683 performed in patients with tumors showing benign calcifica- 8. Potente G, Macori F, Caimi M, Mingazzini P, Volpino P.

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Noncalcified pulmonary hamartomas: computed tomog- 1230-1237 raphy enhancement patterns with histologic correlation. J 12. Park KY, Kim SJ, Noh TW, Cho SH, Lee DY, Paik HC, et al. Thorac Imaging 1999;14:101-104 Diagnostic efficacy and characteristic feature of MRI in 9. Muramatsu Y, Takayasu K, Moriyama N, Shima Y, Goto H, pulmonary hamartoma: comparison with CT, specimen Ushio K, et al. Peripheral low-density area of hepatic tu- MRI, and pathology. J Comput Assist Tomogr 2008;32: mors: CT-pathologic correlation. Radiology 1986;160:49-52 919-925 10. Takayasu K, Ikeya S, Mukai K, Muramatsu Y, Makuuchi M, 13. Poirier TJ, Van Ordstrand HS. Pulmonary chondromatous Hasegawa H. CT of hilar cholangiocarcinoma: late contrast hamartomas. Report of seventeen cases and review of the enhancement in six patients. AJR Am J Roentgenol 1990; literature. Chest 1971;59:50-55 154:1203-1206 14. Hochhegger B, Marchiori E, dos Reis DQ, Souza AS Jr, Souza 11. Furukawa H, Takayasu K, Mukai K, Kanai Y, Inoue K, Ko- LS, Brum T, et al. Chemical-shift MRI of pulmonary hamar- suge T, et al. Late contrast-enhanced CT for small pancre- tomas: initial experience using a modified technique to as- atic carcinoma: delayed enhanced area on CT with histo- sess nodule fat. AJR Am J Roentgenol 2012;199:W331- pathological correlation. Hepatogastroenterology 1996;43: W334

폐과오종의 역동적 전산화단층촬영 소견: 조직병리학적 소견과의 비교1

조왕래1 · 정연주1 · 이창훈2 · 이지원1 · 김건일3 · 염정아3 · 김영대4

목적: 단일폐결절로 나타나는 폐과오종의 역동적 전산화단층촬영 소견을 기술하였으며, 이러한 소견을 병리조직학적 소 견과 비교하였다. 대상과 방법: 본 후향적 연구는 임상시험 심사위원회에 승인을 받았으며, 환자의 동의는 생략하였다. 2004년 3월부터 2012년 3월까지, 우리는 수술적으로 확정된 폐과오종 환자 11명(남성 : 여성 = 6 : 5, 평균연령: 53.6세)의 형태학적, 역 동적 전산화단층촬영 소견을 평가하였다. 11명의 모든 환자는 나선식 역동적 전산화단층촬영을 시행받았다(조영제 정맥 주입 후, 0초, 30초, 60초, 90초, 120초 그리고 4분, 5분, 15분 후 결절에 대해 2.5 mm 폭조절로 연속적인 영상을 획득 하였다). 조영증강 정도와 방식을 종양의 조직학적 구성성분과 비교하였다. 결과: 종양의 평균 장축은 14.8 mm, 표준편차는 ± 5.8 mm였다(범위, 10.0~30.0 mm). 6개의 종양은 매끄러운 경계 를 지니고 있었으며, 5개의 종양은 소형상 모양의 경계를 보였다. 전산화단층촬영에서 지방조직과 석회화는 각각 3개, 1 개의 종양에서 관찰되었다. 모든 11개의 종양은 지속적인 조영증강과 다양한 정도의 순조영증강을 보였다[평균 최고 조영 증강은 48.6 ± 19.0 Hounsfield unit (이하 HU); 평균 순조영증강은 31.9 ± 11.8 HU]. 모든 11개의 종양은 성숙된 연 골과 성긴 결합조직성분으로 구성되었다. 5개의 종양이 지방조직을 가지고 있었다. 순조영증강값과 성긴 결합조직 성분의 비율 간에 유의한 양의 상관관계를 보였으며, 순조영증강값과 연골 조직 비율 간의 음의 상관관계를 보였다. 결론: 역동적 전산화단층촬영에서, 과오종은 모든 경우에서 지속적인 조영증강과 다양한 정도의 순조영증강 그리고 두꺼 운 피막 및 격막 조영증강을 보였다. 순조영증강값은 성긴 결합조직 비율과 양의 상관관계를 보였으며, 두꺼운 피막 및 격 막 조영증강은 종양의 연골 소엽을 나누는 성긴 결합조직(조영증강된 격막)으로부터 기인하는 것으로 판단된다.

부산대학교 의과대학 부산대학교병원 1영상의학과, 2병리과, 4흉부외과, 3부산대학교 의과대학 양산부산대학교병원 영상의학과

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