Pulmonary nodules 10 mm or less in diameter with ground-glass opacity component detected by high-resolution computed tomography have a high possibility of malignancy

Objectives: For the histological diagnosis of small lung cancers of 10 mm or less in diameter (≤10), resection by video-assisted thoracic surgery (VATS) with computed tomography (CT)-guided marking is feasible. One problem is that a small number of these pulmonary nodules are malignant. We retrospectively analyzed CT images of pulmonary nodules to find better criteria to select candidates for resection among patients with small pulmonary nodules. Methods: Ninety-four patients with indeterminate peripheral pulmonary nodules underwent wedge resection by VATS. High-resolution CT using a 1.25 mm slice included the area of lesions. Nodules were classified by size (≤10, 11 to 22,>20 mm) and whether they had a ground-glass opacity (GGO) component. Results: The histology of all 94 nodules showed 52 primary lung cancers, 6 metastatic tumors, 5 benign tumors, 8 intrapulmonary lymph nodes, and 23 inflammatory nodules. Ninety-three percent of nodules larger than 20 mm, 75% of nodules 10 to 20 mm, and 43% of nodules ≤10 mm were malignant. Introducing a classification according to GGO component to nodules, malignancy was detected in 88% of nodules with a GGO component and in 30% of nodules without a GGO component among nodules ≤10 mm. Nodules ≤10 mm with a GGO component showed a statistically significant (p<0.01) correlation with malignancy. Conclusions: Pulmonary nodules ≤10 mm with GGO should be considered to have a high possibility of malignancy and to be candidates for resection by VATS.     

Using an image-guided navigation system for localization of small pulmonary nodules before thoracoscopic surgery

Background Video-assisted thoracic surgery (VATS) provides a minimally invasive means to resect small pulmonary nodules (SPN). However, thoracoscopy has limits in the detection of small nodules, which are invisible and/or impalpable during surgery. Methods to localize such lesions, including methylene blue injection or the introduction of a hookwire under the guidance of computed tomography (CT), have some limitations. We are developing a new technique using image-guided navigation system for localization of small pulmonary nodules before thoracoscopic surgery. Methods Four pigs underwent spiral-computed tomography (CT) scanning after they were given percutaneously created pulmonary lesions. The CT data were transmitted to a StealthStation navigation system, and with the help of the probe the lesions were located and resected under thoracoscopy. Results A total of 20 lesions were created. Nodules were located at an average distance of 15.6 mm from the pleural surface. All the lesions were successfully localized, and biopsy specimens revealed successful resection of target material. Conclusion This method can provide appropriate guidance to small pulmonary nodules and prove effective in immediately facilitating subsequent thoracoscopic resection.     

电视胸腔镜手术前SPECT/CT引导Sens-cure针穿刺定位肺小结节

目的观察电视胸腔镜手术(VATS)前SPECT/CT引导Sens-cure针穿刺定位肺小结节(直径≤10 mm)的价值。方法对19例肺小结节患者行SPECT/CT引导下经皮穿刺定位,共定位21个肺小结节;之后行VATS,根据定位器位置寻找靶病灶,并予以局部楔形切除。观察定位成功率、穿刺定位时间、肺结节大小、胸膜下距离、并发症及病理类型等。结果经皮穿刺定位肺小结节成功率100%,平均定位时间(15.0±3.1)min;病灶最大径(7.1±1.8)mm,胸膜下距离(17.8±5.8)mm;而后均成功完成VATS,完整切除靶病灶,无脱靶。术后病理诊断其中16个(16/21,76.19%)为病变恶性。穿刺后并发症包括少量出血2例、少量气胸3例。结论VATS术前SPECT/CT引导Sens-cure针穿刺定位肺小结节安全有效,可提高VATS成功率。     

Methylene blue-stained autologous blood for needle localization and thoracoscopic resection of deep pulmonary nodules

Background/Purpose: Video-assisted thoracoscopic surgery (VATS) has used a variety of preoperative techniques to localize deep pulmonary nodules including wires, plain methylene blue, colored collagen, indigo carmine, India ink, and barium. The authors describe their experience with a computed tomography (CT)[ndash ]guided localization technique using autologous blood stained with methylene blue. Methods: The authors reviewed retrospectively children who had pulmonary nodules localized using CT guidance with a mixture containing 3mL autologous blood stained with 0.3mL methylene blue. Nodules were resected by standard VATS technique. Postoperative chest tube drainage was performed selectively. Results: Nineteen procedures were performed in 17 children (average age, 11 years). Operating time (range, 21 to 171 minutes) varied depending on the number of nodules resected. All resections were diagnostic, and 80% represented malignancy. Lesions averaged 0.9 cm in size (range, 0.3 to 3 cm) with an average pulmonary depth of 0.8 cm (range, 0.1 cm to 1.8 cm). One patient required conversion to an open thoracotomy because of malfunction of the endoscopic stapler. Forty percent of the children received chest tubes, and 53% were discharged home the same day. Conclusion: VATS diagnostic resection of deep pulmonary nodules preoperatively localized with methylene blue stained autologous blood is safe and effective.     

Video-assisted S6b-subsegmental resection after computed tomography guided localization of pulmonary nodules

A 38-year-old man, who had undergone surgery for gastric cancer one year previously, was found to have two pulmonary nodules (PNs: 10mm in diameter) on chest radiography. Computed tomography (CT) revealed one of these nodules to be located near the B⁶b in the right lung hilus, while the other was located in the superficial region of the left lower lobe. Video-assisted thoracic surgery (VATS) was performed, for both diagnostic and therapeutic purposes. In this procedure, after preoperative CT-guided marking, simultaneous subsegmental resection of the right S⁶b and VATS wedge resection of the left lower lobe were performed successfully with adequate surgical margin. Histological diagnosis was compatible with metastatic pulmonary tumor from a gastric carcinoma primary. This case demonstrates that preoperative CT-guided localization can facilitate safe VATS subsegmental resection of a small deep pulmonary nodule.     

Fluoroscopy-aided thoracoscopic resection of pulmonary nodule localized with contrast media

BACKGROUND: The pulmonary nodules have become the major indication of video-assisted thoracic surgery (VATS). Recently, several preoperative or intraoperative techniques for identifying small or deeply seated pulmonary nodules have facilitated thoracoscopic resection. We describe the new technique for detecting difficult lesions. METHODS: Preoperatively, we marked the visceral pleura near the pulmonary nodules with dye, simultaneously injected contrast media (1 water-soluble Optiray [Mallinckrodt Medical Inc, Quebec, Canada], 18 barium sulfate, 11 Lipiodol [Laboratoire Guerbet, Aulnay-sous-Bois, France]) into or around the nodule under computed tomography (CT) guidance. During VATS, we were able to easily and accurately detect and resect all the nodules localized with contrast media, of which the radiopacity was visualized on the portable fluoroscopic monitor. RESULTS: Between February 1996 and December 1998, we thoracoscopically resected 30 nodules in 28 patients (13 were women; age, 53 +/- 14 years). The resected nodules were 17 +/- 7.6 mm (range; 4 to 32 mm) in size, and 8.9 +/- 8 mm (range, 2 to 34 mm) in depth. The pathologic diagnosis of the nodules was benign in 20 and malignant in 10 (six primary cancers of lung and four metastatic cancers). There were only minor complications related CT localization. CONCLUSIONS: This new technique can help the surgeons detect and resect the difficult lesions with safety and rapidity by VATS without thoracotomy.     

Video-assisted S<Superscript>6</Superscript>b-subsegmental resection after computed tomography guided localization of pulmonary nodules

A 38-year-old man, who had undergone surgery for gastric cancer one year previously, was found to have two pulmonary nodules (PNs: 10mm in diameter) on chest radiography. Computed tomography (CT) revealed one of these nodules to be located near the B⁶b in the right lung hilus, while the other was located in the superficial region of the left lower lobe. Video-assisted thoracic surgery (VATS) was performed, for both diagnostic and therapeutic purposes. In this procedure, after preoperative CT-guided marking, simultaneous subsegmental resection of the right S⁶b and VATS wedge resection of the left lower lobe were performed successfully with adequate surgical margin. Histological diagnosis was compatible with metastatic pulmonary tumor from a gastric carcinoma primary. This case demonstrates that preoperative CT-guided localization can facilitate safe VATS subsegmental resection of a small deep pulmonary nodule.     

Implication of the CT characteristics of subcentimeter pulmonary nodules

Screening by low-dose helical computed tomography (CT) detects many small pulmonary nodules less than 1 cm in diameter. Pulmonary nodules can be practically classified into three types by their CT appearance: pure ground-glass opacity (GGO), GGO with a solid central component, and solid nodule. Ground-glass opacity on thin-section CT is considered to most commonly represent focal bronchoalveolar carcinoma. However, one-third of pure GGOs represent atypical adenomatous hyperplasia. Noguchi has classified small adenocarcinomas into pathological subtypes (A through F) that appear to have clinical significance. Noguchi types D-F can be differentiated from types A, B, and C by CT findings--however, CT does not appear to be able to reliably distinguish D-F lesions and squamous cell carcinoma from benign tumors. The rate of obtaining a correct preoperative diagnosis on the basis of CT findings was significantly elevated after we instituted a program of preoperative evaluation based on defined thin-section CT characteristics of small nodules. Although emerging data suggest that limited resection for malignant lesions 10 mm or less may be appropriate, particularly for Noguchi types A-C, this remains controversial.     

Video-assisted thoracoscopic surgery for pulmonary nodules: rationale for preoperative computed tomography-guided hookwire localization.

OBJECTIVES: Video-assisted thoracic surgery (VATS) provides a minimally invasive means to resect pulmonary nodules (PN). Deep localization of PN may jeopardize VATS lung resection. The aim of this study was to establish the utility of preoperative computed tomography (CT)-guided hookwire localization of PN. METHODS: Between January 1993 and September 2001, we performed 151 VATS resections for PN. Preoperative CT-guided hookwire localization was not performed in 98 patients (group I); it was done just before surgery in 53 patients (group II) when, at CT scan, the distance of PN from the lung surface was >15 and/or when the size was <10 mm. RESULTS: Pneumothorax occurred in four patients (7.5%). Hookwire dislodged in four patients, but the hematoma left on the visceral pleura made thoracoscopic localization possible in three of these. Seventeen patients (17%) in group I and 4 (7.5%) in group II required conversion to thoracotomy (P< or =0.05). The most common reason for conversion was impossibility to localize PN in group I (nine cases) and deep localization requiring local enucleation in group II (two cases). In 31 group II patients (58%) hookwire positioning led to successful VATS resection that would otherwise have been impossible because PN were neither visible nor palpable. CONCLUSIONS: Preoperative CT-guided hookwire localization for pulmonary nodules is an effective technique which allows VATS resection of PN <10 mm located >15 mm from the pleural surface. Even when PN are subpleural but <10 mm, hookwire localization makes VATS resection faster. Apical and diaphragmatic localization of PN are limitations to the procedure.     

Peripheral lung nodules: fluoroscopically guided video-assisted thoracoscopic resection after computed tomography-guided localization using platinum microcoils

OBJECTIVES: We sought to test the safety and efficacy of fluoroscopically guided, video-assisted, thoracoscopic resection after computed tomography (CT)-guided localization using platinum microcoils. SUMMARY BACKGROUND DATA: Video-assisted thoracoscopic (VATS) resection of small pulmonary nodules >5 mm deep to the visceral pleura fails to locate the nodule and requires conversion to open thoracotomy in two thirds of cases. Therefore, we developed a new technique for intraoperative localization of these nodules using CT-guided placement of platinum microcoils. This study tests the safety and efficacy of this technique in a Phase I human study. METHODS: Twelve patients with undiagnosed growing pulmonary nodules <20 mm were marked preoperatively using percutaneously placed CT-guided platinum microcoils. The coil was deployed adjacent to the nodule with the distal end of the coil placed deep to the nodule and the superficial end coiled on the pleural surface. The nodule and coil were excised using endostaplers guided by VATS and fluoroscopy. Histopathologic diagnosis was performed immediately after resection. RESULTS: CT-guided microcoil localization was successful in all patients. A small hemothorax and a pneumothorax requiring a chest tube occurred in 2 patients. Mean distance from visceral pleura to the deep edge of the nodule was 30.9 +/- 15.4 mm. VATS resection of the nodules (size = 11.8 +/- 3.2 mm) was successful in all patients. Mean microcoil localization, fluoroscopy, and operative times were 42 +/- 14, 3.1 +/- 2.0, and 67 +/- 27 minutes. A diagnosis of primary nonsmall cell bronchogenic carcinoma was made in 6 patients who then received a completion lobectomy. Six patients (hamartoma: 2, reactive lymph node: 1, bronchoalveolar cell carcinoma: 2, metastatic sarcoma: 1) did not receive further resections. CONCLUSIONS: Preoperative localization of pulmonary nodules using percutaneous CT-guided platinum microcoil insertion combined with operative fluoroscopic visualization is a safe, effective technique that increases the success rate of VATS excision.     

肺内小结节电视胸腔镜切除术前CT定位

目的探讨CT引导下微弹簧圈定位指引电视胸腔镜手术(VATS)切除肺内小结节的安全性和有效性。方法对47例肺内小结节患者(共53个结节,直径30mm)行术前CT引导下微弹簧圈定位,将微弹簧圈植入紧邻肺小结节边缘的肺组织内,使22个结节内的微弹簧圈的尾部位于脏层胸膜之外。于定位当日或次日行VATS切除肺内小结节,术后标本送病理学检查。结果 VATS下完整切除全部肺内小结节(直径3~26mm)。51个(51/53,96.23%)肺内小结节应用微弹簧圈定位成功,2个(2/53,3.77%)微弹簧圈植入后发生移位;定位术中并发症包括无症状性气胸6例、轻微肺泡出血9例。结论术前CT引导下经皮穿刺微弹簧圈定位肺内小结节安全、有效,有助于提高VATS切除的准确率。     

对比CT引导肺结节定位针与弹簧圈定位针术前定位亚厘米肺结节效果

目的 对比术前于CT引导下以肺结节定位针与弹簧圈定位针定位亚厘米肺结节的效果。方法 55例亚厘米肺结节(孤立性肺结节,最大径4～10 mm,距胸膜<50 mm)患者于电视辅助胸腔镜手术(VATS)前48 h内接受CT引导下定位病灶,其中30例采用肺结节定位针(定位针组)、25例采用弹簧圈定位针(弹簧圈组),对比2种方法定位时间、CT扫描次数、定位成功率、病灶楔形切除时间、手术成功率及并发症。结果 55例均顺利完成术前定位且VATS均成功切除病灶。2种定位方法之间,CT扫描次数、病灶楔形切除时间及气胸、肺内出血发生率差异均无统计学意义(P均>0.05)。以定位针定位时间长于弹簧圈(P=0.001)。结论 术前于CT引导下以肺结节定位针与弹簧圈定位针定位亚厘米肺结节的安全性和有效性相当,后者操作时间更短。     

肺结节胸腔镜切除术前微弹簧圈定位相关并发症及其影响因素

目的 观察电视辅助肺结节胸腔镜切除术（VATS）术前定位微弹簧圈相关并发症,并分析其影响因素。方法 回顾性分析160例肺结节患者（160个结节）,均于VATS切除结节前行CT引导下微弹簧圈定位,统计定位术后并发症,分析其影响因素。结果 160例结肺节均以微弹簧圈成功定位,术中26例出现气胸,37例发生肺内出血,未见空气栓塞。所有患者于次日接受VATS,术中均未发现微弹簧圈移位。单因素分析结果显示,患者体位（P=0.04）、结节距胸膜距离（P=0.03）及穿刺次数（P<0.01）与微弹簧圈定位术后发生气胸相关,结节距胸膜距离（P=0.03）与微弹簧圈定位术后发生肺内出血相关。多因素分析结果显示,患者体位、结节距胸膜距离及穿刺次数是微弹簧圈定位术后发生气胸的独立危险因素（P均<0.05）,结节距胸膜距离则是肺内出血的独立危险因素（P=0.01）。结论 肺结节VATS术前微弹簧圈定位可出现气胸和肺内出血,前者与结节距胸膜距离、患者体位及穿刺次数相关,后者仅与结节距胸膜距离相关。     

A clinicopathological study of resected pulmonary nodules with focal pure ground-glass opacity.

OBJECTIVE: Pulmonary lesions with focal ground-glass opacity (GGO) have been detected increasingly by low-dose helical computed tomography (CT). However, the strategy of treatment for focal pure GGO lesions is still undecided. This study evaluates clinicopathological characteristics of resected pulmonary nodules with focal pure ground-glass opacity. METHODS: Between January 1997 and December 2005, 26 patients (35 lesions) with pure GGO lesions underwent pulmonary resection. The data on patient age, lesion size, pathology, carcinoembryonic antigen (CEA) level and palpability of the tumor in the resected specimen were evaluated. RESULTS: The histological diagnosis was bronchioloalveolar carcinoma (BAC) in 10 patients (12 lesions), atypical adenomatous hyperplasia (AAH) in 15 patients (22 lesions), and focal scar in 1 patient (1 lesion). There were no significant differences in age, sex, tumor size, and CEA level between the patients with BAC, AAH, and focal scar. However, the lesions >10mm in size were all BAC. Palpability of the tumor in the resected specimen was significantly more frequent in BAC cases than in AAH cases (p<0.01). For BAC, lobectomy was performed for four lesions, and limited resection for eight. None of the BACs showed lymphatic or vascular invasion upon pathological examination. At the median follow-up point of 44 months (range: 4-84 months), no recurrences were observed. CONCLUSIONS: BAC and AAH cannot be discriminated by their size. In the resected specimen, BAC lesions are more frequently palpable than AAH lesions. Thoracoscopic surgery is recommended for focal pure GGO after repeated CT even if the GGO lesion is small. Partial resection is a sufficient treatment for pure GGO.     

Preoperative marking of a submillimeter metastatic pulmonary tumor using a mobile computed tomography scan with a navigation system: A case report

Introduction and importancePreoperative localization of non-palpable lung nodules plays an important role in video assisted thoracic surgery (VATS). Although percutaneous computed tomography (CT)-guided hook wire marking has become widely accepted, it is accompanied by rare but fatal complications such as air embolisms. We herein report a case of a submillimeter pulmonary nodule successfully localized by a mobile CT scan with a navigation system.Case presentationA 40-year-old-man presented with the two right pulmonary nodules 4 years after a radical left nephrectomy for a renal clear cell carcinoma. One of the nodules was too small to palpate and preoperative marking was applied using a mobile CT scan with a navigation system. We successfully performed VATS wedge resection for both nodules and confirmed a pathological diagnosis of a metastasis from the renal cell carcinoma. The maximum pathological size of the smaller nodule was 500 μm.Clinical discussionPreoperative marking of the lower lobe lesion in the present case was essential for VATS. Our novel technique was helpful for the precise marking without any morbidity.ConclusionPreoperative marking using a mobile CT scan with a navigation system is safe and easily applicable. It might be a useful option for VATS of non-palpable lung nodules.     

Pulmonary nodule. The surgeon's approach

Malignancy must be suspected with any pulmonary nodule detected on radiologic examination of the chest until its benign origin has been proven. This requires further evaluation of the patient. The non invasive diagnostic steps include patient's history, clinical examination, lung function testing, and standard radiographs and a computed tomography (CT) of the chest. Based on these findings the presumed diagnosis claims the next appropriate diagnostic steps. If lung cancer is the most likely diagnosis and lung function testing revealed that the patient is a candidate for lung resection than surgery may be the next step. Preoperative proof of the histologic diagnosis is not mandatory. It is the less required the more surgery may be curative. If curative resectability is indoubt or the patient is not candidate for lung resection than histologic diagnosis should be confirmed prior to introduction of radiotherapy or chemotherapy by the least invasive procedure (bronchoscopy < lymph node biopsy < needle biopsy < mediastinoscopy/-tomy < VATS). If metastatic disease must be suspected, staging should be completed as required for the primary malignancy. With local recurrence and other metastases excluded the number of pulmonary nodules detected on CT scan points to the appropriate surgical approach. In case of a solitary nodule or multiple but resectable nodules, complete (wedge) resection with lymph node dissection through a lateral thoracotomy will be the procedure of choice. With multiple and unresectable nodules, surgery allows definitive diagnosis and videothoracoscopy affords the opportunity to accomplish wedge resection of the lung along with low morbidity. When lesions are deemed indeterminate, definitive diagnosis should nevertheless be attempted. If there is no history of malignancy routine evaluation for such in asymptomatic patients is not indicated. With small nodules (less than 3 cm in diameter) located in the periphery of the lung, videothoracoscopic wedge resection is indicated without preoperative sputum cytology, bronchoscopy or transthoracic needle biopsy. The histologic diagnosis obtained by intraoperative frozen sections than determines the further surgical approach. Benign lesion: completion of surgery; lung cancer: proceed to thoracotomy with anatomic lung resection and mediastinal lymph node resection; metastatic disease: completion of surgery and further search for primary malignancy.     

Surgical approach for lung cancer with multiple pulmonary nodules

A computed tomography (CT) and high-resolution CT (HRCT) have provided us an increasing opportunity to find multiple small pulmonary nodules, which sometimes appear ground glass opacity (GGO). Recently, fluorodeoxyglucose-positron emission tomography (FDG-PET) had a great contribution to our assessment for these small pulmonary nodules. However, since it is yet difficult to establish a diagnosis for these nodules during preoperative workup, a surgical lung biopsy is often required for an accurate diagnosis. We have experienced 9 patients who had undergone lung resection for primary lung cancer accompanied by multiple pulmonary lesions. Since the multiple lesions were consisted of malignant and benign lesions, it is still uncertain whether excessive lung resection should be performed in such patients. In this brief article, we summarized the characteristics of the pulmonary lesions in those patients and discussed difficulty of preoperative diagnosis, viability of pulmonary resection and problems underlining a surgical treatment.     

Intraoperative ultrasound during thoracoscopic procedures for solitary pulmonary nodules.

BACKGROUND: Traditional nonoperative diagnostic approaches to the solitary pulmonary nodule (bronchoscopy and percutaneous needle biopsy) can be inconclusive. Video-assisted thoracic surgery (VATS) provides a minimally invasive way to diagnose and treat these nodules. We evaluated the use of a dedicated intraoperative ultrasound probe as an aid in localization of small pulmonary nodules during VATS. METHODS: An intraoperative ultrasound examination during a thoracoscopic procedure was performed on 18 patients to localize deep pulmonary nodules less than 20 mm in diameter without a definitive diagnosis by preoperative imaging techniques. RESULTS: In the 18 patients, all nodules were successfully identified by intraoperative ultrasound. A definitive pathologic diagnosis was obtained from thoracoscopic biopsy or resection. The final diagnoses were primary lung cancer in 5 patients, metastatic lesions in 4 patients, hamartoma or chondroma in 4, granuloma in 3, and interstitial fibrosis in 2 patients. CONCLUSIONS: In our experience, intraoperative ultrasound can safely and effectively localize invisible or nonpalpable pulmonary nodules at the time of thoracoscopy. This may help surgeons perform minimally invasive lung resections with clear surgical margins.     

Surgical procedure of segmentectomy as a possible cause of postoperative cerebral embolism: a case report

Video assisted thoracoscopic surgery (VATS) can currently be used to diagnose and treat pulmonary nodules. However, intraoperative location of pulmonary nodules in VATS is challenging due to their small diameter and deep location in the pulmonary parenchyma. The purpose of this study was to report the clinical safety and effectiveness of CT-guided hook-wire for preoperative localization of malignant pulmonary nodules smaller than 1 cm in diameter. From February 2017 to January 2018, we collected the data of 80 patients with malignant pulmonary nodules less than 1 cm in diameter who underwent CT-guided hook-wire preoperative localization and VATS surgery. The effectiveness of preoperative localization was evaluated based on surgical duration, success rate of VATS surgery, and localization-related complications. The diameter of pulmonary nodules were 0.85 ± 0.17 mm with a distance to the pleural surface of 19.66 ± 14.10 mm. The length of the hook-wire in the lung parenchyma was 29.17 ± 13.14 mm and hook-wire dislodgement occurred in 2 patients. Complications included 27 cases of minor pneumothorax and 18 cases of mild parenchymal hemorrhage. A significant correlation was observed between the length of the hook-wire in the lung parenchyma and mild parenchymal hemorrhage (P = 0.044). The average time of hook-wire localization was 9.0 ± 2.6 min and the average operation time for VATS was 89.02 ± 23.35 min without conversion thoracotomy. CT-guided hook-wire localization of the lesion during VATS resection is safe for malignant pulmonary nodules with diameter less than 1 cm.     

Ultrasonographic evaluation of small nodules in the peripheral lung during video-assisted thoracic surgery (VATS).

OBJECTIVE: We examined the possibility of intraoperative ultrasonography during video-assisted thoracic surgery (VATS) to localize and make a qualitative diagnosis of small peripheral pulmonary nodules. METHODS: Ultrasonography during VATS and conventional thoractomy was performed on 25 and 18 nodules, respectively, all which were localized in the peripheral lung, were less than 30 mm in diameter and for which there was no definitive diagnosis. RESULTS: All 25 nodules, including 10 invisible but palpable and three both invisible and non-palpable, could be localized by ultrasonography during VATS. If nodules were located less than 15 mm from the pleural surface, ultrasonography during VATS could detect nodules 10 mm or less in diameter. The rate of malignant tumors among 11 of 12 pulmonary nodules (91.6%) showing both heterogeneous and ill-defined patterns was significantly higher than 6 of 16 nodules (37.5%) showing both homogeneous and well-defined patterns on ultrasonography. CONCLUSIONS: Our study suggested that ultrasonography during VATS is useful for the detection of peripheral pulmonary nodules, even when they are not identified on video images or palpation, and may enable a differential diagnosis between malignant and non-malignant lesions.