Computed tomography of the solitary pulmonary nodule

The value of computed tomography (CT) using thin-slice technique in the differentiation between benign and malignant pulmonary nodules was evaluated both experimentally and clinically. Experiments using a standard reference phantom and simulation nodules showed that CT number varies according to the size of the nodule and the difference of CT unit. A standard CT number above which a nodule should be considered as calcified and benign was first calculated for various sizes of nodules and then was applied to clinical cases. Motion artifact which can give falsely high CT numbers was also created and its characteristic appearance was identified. Clinically 101 cases of solitary pulmonary nodules whose diagnoses were confirmed either histologically or on follow-up were studied. There were 40 benign nodules, 53 primary lung cancers, and 8 metastatic lung tumors. There was no case of malignancy in which calcification was diagnosed to be present on CT. On the other hand, 14 of 40 benign nodules (35.0%) was diagnosed to contain calcium and therefore benign on CT. As for the margin of the nodule described on CT, a moderate to marked irregularity was predominantly seen in primary lung cancers, while most benign nodules and metastatic lung tumors had smooth margins. If CT criteria for benignancy are limited to the nodule both with calcification and smooth margin, 13 of 40 cases (32.5%) would be correctly diagnosed. CT is considered to be useful in distinguishing between benign and malignant solitary pulmonary nodules as far as herein described technique is observed.     

60例3厘米以下肺内球形病灶瘤─肺界面CT─病理对照分析

本文复习了经手术病理证实的直径≤３ｃｍ的肺内孤立性球形病灶６０例（肺癌４２例、良性结节１８例）的ＣＴ像。ＣＴ像显示结节边缘粗糙者小肺癌占８１％，良性结节占２８％。结节主要ＣＴ像层面上多毛刺（多于６根）结节小肺癌占７１％，良性结节仅占１１％。ＣＴ像见结节边缘有锯齿征９例，病理证实均为肺癌，此征与癌灶边缘不等速浸润生长有关。ＣＴ－病理对照结果显示锯齿征是诊断周围型小肺癌很重要的一个ＣＴ征象，ＣＴ像上结节边缘光滑程度及毛刺数的多少有助于肺周围球形小病灶的良、恶性鉴别诊断。     

Calcification in pulmonary nodules: detection with dual-energy digital radiography

The authors undertook a clinical study to determine the accuracy of dual-energy digital radiography in revealing nodule calcification because calcification in a pulmonary nodule almost excludes the possibility of malignancy. Over a 6-month period, 61 patients with pulmonary nodules (less than or equal to 3 cm) or masses (greater than 3 cm) were examined on a prototype scanned projection unit using a dual-energy detector. In 49 of 61 patients, nodules were noncalcified, and in 12, they were calcified. In 57 patients, the benignancy or malignancy of nodules was established beyond reasonable doubt by pathologic confirmation in 38 and by strong inference in 19 (four patients with noncalcified solitary pulmonary nodules either refused further investigation or surgery or their follow-up was too short to permit exclusion of malignancy). Dual-energy radiography was found to be highly accurate in assessing the presence or absence of calcification in pulmonary nodules and thus in determining their benignancy or possible malignancy.     

Small solitary pulmonary nodule and high-resolution CT: a preliminary report

In the attempt to separate primary lung cancers and benign lesions presenting as solitary pulmonary nodules (SPNs) the authors studied prospectively 52 SPNs less than 30 mm in diameter by means of high-resolution (HRCT). Patients with known cancer were excluded. Margins, internal structure, bronchus sign, calcifications, pleural tag and gross morphology of SPN were considered. Spiculation, air inside the nodule and bronchus sign were found in cancer and in one benign lesion (spiculation). All other benign SPNs presented smooth margins without bronchus sign or air inside the mass. Final diagnosis was obtained with surgery, fine-needle-aspiration biopsy or 12-month follow-up. Of 52 nodules, 28 proved malignant, and 24 of 52 proved benign. Sensitivity and specificity of HRCT for diagnosing malignancy of the nodule were 100% and 96%, respectively. In conclusion, we think that HRCT is useful in the differentiation of cancers from benign lesions presenting as SPNs in the majority of patients without known neoplasm. Correspondence to: L. Volterrani     

HIV阴性肺隐球菌病CT表现

目的 分析HIV阴性肺隐球菌病的CT表现,提高对本病的认识及诊断水平.资料与方法 回顾性分析2000-04～2011-10经病理或临床证实的20例HIV阴性肺隐球菌患者(包括7例免疫功能抑制者)的CT图像及临床资料.结果 ①肿块或结节型8例,其中孤立病灶3例,多发病灶5例,下肺、外周分布为主.②实变型7例,其中局限病灶3例,密度较高,边界较清;多发病灶4例,双肺散在分布.③混合型5例,表现为结节、团块、实变及磨玻璃影混合存在.20例患者中,晕征6例(30％),空洞11例(55％),支气管气相为10例(50％).结论 肺隐球菌病CT表现多样,病灶以下肺及外周分布为主,晕征、空洞及支气管气相有一定提示意义,有助于作出早期诊断,减少误诊.     

含气支气管征在CT诊断周围型小肺癌的价值

目的:探讨周围型小肺癌内含气支气管的病理基础、CT表现及其诊断价值。方法:回顾性分析经手术病理证实的46例周围型小肺癌(直径≤3 cm)及22例孤立性良性结节含气支气管征的薄层CT表现,其中腺癌31 例,细支气管肺泡癌6例,鳞癌5例,腺鳞癌3例,小细胞癌1例。结果:46 例肺癌中,CT上显示含气支气管征20 例(43.5%),其中腺癌显示含气支气管征17例、肺泡癌2例、鳞癌1例,其他类型的肺癌未见此征。病灶内含气支气管影形态改变主要表现为管腔不规则狭窄、扭曲、扩张与中断。22例良性结节中,CT显示含气支气管征1例,其影像表现为管腔通畅,形态无明显异常。结论:孤立性肺结节内含气支气管征的出现,特别是形态学改变对周围型小肺癌的诊断具有重要的临床价值。     

CT diagnosis of solitary pulmonary nodule]

The CT (including HRCT) findings of solitary pulmonary nodule (SPN) were reviewed. CT currently is the imaging modality of choice for the evaluation of SPN. Important roles of CT are detecting pulmonary nodules and distinguishing malignant nodules from other benign tumors or inflammatory masses. To differentiate malignancy from benignancy, it is necessary to evaluate the CT findings of SPN, including morphology using HRCT, attenuation of the nodules using thin-section CT, and enhancement effect on contrast-enhanced CT. Also important in this distinction is the evaluation of satellite lesions around SPN and the relationships between bronchus, artery, vein, pleura, and interlobular septum. Spiral CT has greatly expanded the usefulness of CT in the evaluation of SPN and has become the imaging modality of choice for SPN by combining the advantages of a single breath-hold acquisition and improved MPR and three-dimensional reconstruction capabilities. MPR and three-dimensional images of spiral CT can also be used to display the three-dimensional relationship between SPNs and bronchus, vessels, or pleura.     

CT增强扫描高密度点条征在周围型肺癌诊断中的意义

目的 采用CT增强扫描评价“高密度点条征”在周围型肺癌诊断中的意义。材料与方法 89例经手术或穿刺病理证实的孤立性肺结节（直径1－5cm)中,周围型肺癌63例,良性肺结节26例,分别于注射100ml碘对比剂前后注射后35秒、2分钟及5分钟对病灶进行薄层系列扫描。采用纵隔窗观察病灶的强化特征,并进行CT－病理对照研究。结果 27肺癌出现“高密度点条征”,表现为增强后在肿块内、尤其是在其周边部出现显著高密度的点、条状影、所有良性结节均未见此征象。CT－病理对照证实：该点、条状高密度影响是由于癌肿内较大的血管充盈对比剂所致。结论 CT增强扫描“高密度点条征”在周围型肺癌的诊断中具有非常重要的价值,是诊断肺癌的一个指征。     

CT screening for lung cancer: frequency and significance of part-solid and nonsolid nodules

OBJECTIVE: In the Early Lung Cancer Action Project (ELCAP), we found not only solid but also part-solid and nonsolid nodules in patients at both baseline and repeat CT screening for lung cancer. We report the frequency and significance of part-solid and nonsolid nodules in comparison with solid nodules. MATERIALS AND METHODS: We reviewed all instances of a positive finding in patients at baseline (from one to six noncalcified nodules) and annual repeat screenings (from one to six newly detected noncalcified nodules with interim growth) to classify each of the nodules as solid, part-solid, or nonsolid. We defined a solid nodule as a nodule that completely obscures the entire lung parenchyma within it. Part-solid nodules are those having sections that are solid in this sense, and nonsolid nodules are those with no solid parts. Chi-square statistics were used to test for differences in the malignancy rates. RESULTS: Among the 233 instances of positive results at baseline screening, 44 (19%) involved a part-solid or nonsolid largest nodule (16 part-solid and 28 nonsolid). Among these 44 cases of positive findings, malignancy was diagnosed in 15 (34%) as opposed to a 7% malignancy rate for solid nodules (p = 0.000001). The malignancy rate for part-solid nodules was 63% (10/16), and the rate for nonsolid nodules was 18% (5/28). Even after standardizing for nodule size, the malignancy rate was significantly higher for part-solid nodules than for either solid ones (p = 0.004) or nonsolid ones (p = 0.03). The malignancy type in the part-solid or nonsolid nodules was predominantly bronchioloalveolar carcinoma or adenocarcinoma with bronchioloalveolar features, contrasting with other subtypes of adenocarcinoma found in the solid nodules (p = 0.0001). At annual repeat screenings, only 30 instances of positive test results have been obtained; seven of these involved part-solid or nonsolid nodules. CONCLUSION: In CT screening for lung cancer, the detected nodule commonly is either only part-solid or nonsolid, but such a nodule is more likely to be malignant than a solid one, even when nodule size is taken into account.     

Solitary pulmonary nodules: Part I. Morphologic evaluation for differentiation of benign and malignant lesions.

The solitary pulmonary nodule is a common radiologic abnormality that is often detected incidentally. Although most solitary pulmonary nodules have benign causes, many represent stage I lung cancers and must be distinguished from benign nodules in an expeditious and cost-effective manner. Evaluation of specific morphologic features of a solitary pulmonary nodule with conventional imaging techniques can help differentiate benign from malignant nodules and obviate further costly assessment. Small size and smooth, well-defined margins are suggestive of but not diagnostic for benignity. Lobulated contour as well as an irregular or spiculated margin with distortion of adjacent vessels are typically associated with malignancy. There is considerable overlap in the internal characteristics (eg, attenuation, cavitation, wall thickness) of benign and malignant nodules. The presence of intranodular fat is a reliable indicator of a hamartoma. The presence and pattern of calcification can also help differentiate benign from malignant nodules. Computed tomography (CT) (particularly thin-section CT) is 10-20 times more sensitive than standard radiography and allows objective, quantitative assessment of calcification. Initial evaluation often results in nonspecific findings, in which case nodules are classified as indeterminate and require further evaluation to exclude malignancy. Growth rate assessment, Bayesian analysis, contrast material-enhanced CT, positron emission tomography, and transthoracic needle aspiration biopsy can be useful in this regard.     

螺旋CT薄层扫描诊断肺真菌病的价值

目的 研究螺旋CT薄层扫描在肺真菌感染诊断中的临床价值.资料与方法 对38例肺真菌感染患者的螺旋CT薄层扫描图像进行分析,并结合病理学总结不同真菌的影像特征.结果 38例中肺曲霉菌16例,螺旋CT薄层扫描主要表现为软组织密度结节或肿块(14/16),其中7例病灶周围形成浅淡的、"磨玻璃"样晕环;典型肺曲菌球表现为"空气半月征"(5/16).肺隐球菌10例,CT表现为结节、团块及实变影,内部可见"细支气管充气征"(3/10).肺白色念珠菌9例,表现为两肺野散在或布满大小不一、密度不均的絮片状影,边缘模糊,伴有大小不等的结节影.肺毛霉菌3例,表现为"磨玻璃"样及结节影.结论 螺旋CT薄层扫描可以清晰显示肺内病灶的形态特点,提示"晕征"、"空气半月征"、"洞内球征"、"细支气管充气征"及"树芽征"较特异的征象.不同真菌种类其螺旋CT薄层扫描征象亦有所差别,但最终需结合病理学做出诊断.     

CT screening for lung cancer: suspiciousness of nodules according to size on baseline scans

PURPOSE: To assess the frequency with which a particular, possibly optimal work-up of noncalcified nodules less than 5.0 mm in diameter identified on initial computed tomographic (CT) images at baseline screening leads to a diagnosis of malignancy prior to first annual repeat screening, compared with a possibly optimal work-up of larger nodules. MATERIALS AND METHODS: Two series of baseline CT screenings in high-risk people were retrospectively reviewed. The first series (n = 1,000) was performed in 1993-1998; the second (n = 1,897), in 1999-2002. In each series, cases in which the largest noncalcified nodule detected was less than 5.0 mm in diameter and those in which it was 5.0-9 mm were reviewed to determine whether diagnostic work-up prior to first annual repeat screening showed or would have shown nodule growth and led or would have led to a diagnosis based on biopsy or surgical specimens. RESULTS: The frequency with which malignancy was or could have been diagnosed when the largest noncalcified nodule was less than 5.0 mm in diameter was 0 of 378, whereas when the largest noncalcified nodule was 5.0-9 mm in diameter, the frequency was 13 or 14 of 238. If persons with only nodules smaller than 5.0 mm had merely been referred for first annual repeat screening without immediate further work-up, the referrals for such work-up would have been reduced by 54% (from 817 [28%] to 385 [13%] of 2,897). CONCLUSION: In modern CT screening for lung cancer at baseline, detected noncalcified nodules smaller than 5.0 mm in diameter do not justify immediate work-up but only annual repeat screening to determine whether interim growth has occurred.     

Pleural thickening associated with solitary pulmonary nodule: evaluation with thin-slice CT

Thin-slice CT was performed in 39 cases with a solitary pulmonary nodule abutting on the chest wall. Fifteen cases had bronchogenic carcinomas and the other 24 had benign non-neoplastic pulmonary nodules. CT findings were evaluated retrospectively paying special attention to the angle of the lesion with adjacent pleura, the homogeneity of the boundary between the lesion and the pleura, the configuration of the pleural thickening (broad or not, symmetric or not, tapering or not) and the visibility of the extrapleural fat plane. The broad, symmetric and tapering pleural thickening was seen in one of the 15 cases with a bronchogenic carcinoma and in 11 of the 24 cases with a benign non-neoplastic pulmonary nodule. Our result showed that the broad, symmetric and tapering pleural thickening might be indicative of benign pulmonary nodule. The authors concluded that thin-slice CT might be useful in the evaluation of the benignity of a solitary pulmonary nodule abutting on the chest wall.     

Clinical significance of small pulmonary nodules with little or no 18F-FDG uptake on PET/CT images of patients with nonthoracic malignancies.

Small pulmonary nodules with little or no perceptible (18)F-FDG uptake are relatively common findings on combined PET/CT images of patients with nonthoracic malignancies. Interpreting such nodules is often a diagnostic challenge, and this study aimed to evaluate the clinical significance of the nodules. METHODS: Patients with pulmonary nodules < or =1 cm in diameter showing no (18)F-FDG uptake or uptake less than the mediastinal background were included. Nodules with clearly benign or metastatic findings on CT were excluded. One hundred twenty-one patients had either tissue confirmation or clinical follow-up with additional chest images. The subjects were studied by 3 variables: (i) solitary versus multiple nodules, (ii) presence of accompanying benign lung lesion versus absence, and (iii) imperceptible (18)F-FDG uptake versus faint (18)F-FDG uptake. The malignancy rates were calculated for each variable. RESULTS: Of the 121 patients, 24 had malignancy, with a strong possibility of pulmonary metastasis (19.8%). Six of the 44 patients with solitary nodules (13.6%) and 18 of the 77 patients with multiple nodules (23.4%) had malignancies, though there was no statistically significant difference in the incidences of malignancy between the solitary and multiple groups. On the other hand, there was a statistically significant difference (P = 0.040) between the accompanying lung lesion present (8.3%) and absent (24.7%) groups. No statistically significant difference was noted between the (18)F-FDG uptake imperceptible group and faint (18)F-FDG uptake group (20.7% vs. 17.2%). CONCLUSION: For patients with incidental lung nodules of indeterminate nature with no (18)F-FDG uptake or uptake less than that of the mediastinum on PET/CT images, >19% of the cases turned out to be malignant. The nodule was more likely to be malignant when no other benign pulmonary lesions could be identified elsewhere in the lung field. Thus, regardless of the number of nodules and (18)F-FDG uptake, tissue confirmation or close imaging follow-up is necessary when small nodules with imperceptible or faint (18)F-FDG activity are present on the PET/CT images, especially in the absence of accompanying benign lung lesions.     

The pulmonary nodule: clinical and radiological characteristics affecting a diagnosis of malignancy

The role of computed tomography (CT) in the diagnosis of the solitary pulmonary nodule (SPN) is constantly expanding. CT helps to detect a growing number of increasingly small lesions, but, as with chest radiography, the primary goal in the evaluation of small pulmonary nodules is to exclude malignancy. Despite the availability of numerous, variously invasive, diagnostic tests, diagnostic accuracy tends to decline as the size of the nodule decreases. The role of the radiologist is therefore to help the clinician determine the most appropriate management strategy by using all available modalities [CT, magnetic resonance (MR) imaging, positron emission tomography (PET)] and evaluating the patient’s clinical history and the imaging features leading to a diagnosis of benignity or malignancy. Imaging features include nodule size, margins, calcifications and fatty component, internal features (cavitations, pseudocavitations, air bronchogram, halo sign), as well as advanced techniques for characterisation (growth rate, contrast enhancement) and management (computer-aided diagnosis, Bayesian analysis, neural networks). The aim of this paper is to summarise the approach to pulmonary nodules from the point of view of the radiologist, oncologist and thoracic surgeon.     

肺内孤立结节的CT诊断：CT,普通X线与病理对照研究

A correlative study of CT, X-ray and pathology was done on 41 cases with pulmonary solitary nodule, including peripheral lung cancer 30 cases, benign lesion 10 and metastatic tumor 1. Results showed that CT was more sensitive than conventional X-ray in depicting the characteristic signs such as spiculate protuberance, minute calcifications, small vacuole sign and retraction of pleura. 2 mm thin slice CT scanning is helpful in differential diagnosis of lesions less than 2 cm in diameter. Correlation of CT findings with pathology indicated that spiculate protuberance was caused by infiltrative growth of tumor, whereas the small vacuole sign represented remnant of air containing cavity or slit. The shaggy border of inflammatory nodule was the result of extension of inflammatory process. A correct diagnosis of pulmonary solitary nodule lies in comprehensive analysis of CT manifestations. There is greater possibility of malignancy with mass greater than 4 cm in diameter, lobulation and spiculation are frequently present. Lung cancer less than 3 cm in diameter often presents as lobulated mass with spicules, small vacuole sign and pleural retraction.     

Bronchus sign on CT in peripheral carcinoma of the lung: value in predicting results of transbronchial biopsy

The bronchus sign on CT represents the presence of a bronchus leading directly to a peripheral pulmonary lesion. We investigated the value of this sign in predicting the results of transbronchial biopsy and brushing in 33 consecutive cases of proved peripheral bronchogenic carcinoma studied with thin-slice CT (2-mm-thick sections). The bronchus sign was seen on CT in 22 patients and was absent in 11. Transbronchial biopsy and brushing showed peripheral carcinoma in 13 (59%) of 22 patients in whom the bronchus sign was seen on CT and in only two (18%) of 11 patients in whom it was not seen. The difference is statistically significant (Fisher's exact test, p = .029). When analyzed by the order of involved bronchus, a 90% success rate of transbronchial biopsy and brushing was found in patients in whom the bronchus sign was seen at a fourth-order bronchus (p = .01). This compared with a success of 33% when the bronchus sign was seen at fifth-, sixth-, or seventh-order branches. Our results suggest that the bronchus sign at a fourth-order bronchus is valuable in predicting the success of transbronchial biopsy and brushing. The presence of the sign on CT may be useful in determining if the workup should include transbronchial biopsy and brushing or transthoracic needle aspiration in patients with peripheral lung lesions.     

肺隐球菌病CT征象分析

目的 分析经病理证实的肺隐球菌病(PC)的CT影像表现,加深对本病影像征象的认识及提高诊断水平.方法 回顾性分析经穿刺或手术病理证实的19例PC患者的CT影像及临床资料.结果 ①结节或肿块型10例,结节型多见,直径1~2.5 cm,多发结节易融合.斑片、实变浸润型6例,所见斑片或实变的密度较炎性斑片高,边界多清楚.双肺病灶多为一侧为主,另一侧受累.混合型3例,表现为结节、实变及磨玻璃影等混合存在,均为双肺分布.②病灶分布特点为下肺分布(47%)及胸膜下分布(68%),多为轻~中度强化.③19例患者中,出现影像征象依次为胸膜增厚8例(42%),支气管气相7例(36%),晕轮征5例(26%),空洞4例(21%).结论 PC的CT表现具有多样性.①病灶以下肺及近胸膜分布多见.②病变多为轻~中度强化.③胸膜增厚、支气管气相、晕轮征、空洞等征象对诊断有一定提示意义.     

孤立性肺结节CT征像在鉴别良恶性结节中的价值

目的 探讨孤立性肺结节的各种CT征像对良恶性结节鉴别的意义.方法 选取41例术后病理结果的孤立性肺结节CT征像,依据病理结果把病例分成恶性结节组23例,良性结节组18例,对两组患者的性别、年龄及结节直径对比分析,对孤立性肺结节的毛刺征、分叶征、胸膜尾征、血管集束征、空泡征、磨玻璃结节及钙化等CT征像进行单一CT征像及组...     

肺孤立结节CT增强动态扫描的研究(附36例)

目的：评估肺部孤立结节ＣＴ增强动态扫描特征。方法：３６例肺部孤立结节中恶性肿瘤（均为肺癌）２４例,炎症结节７例,结核球５例。以１００ｍｌ／ｍｉｎ速度静脉注射１．５ｍｌ／ｋｇ体重碘造影剂后行动态薄层扫描,层厚２ｍｍ,层间距２ｍｍ。测量增强前后各层次病灶ＣＴ值。结果：结核球无显著强化,炎症结节及恶性肿瘤均呈显著强化,结核球与炎症结节／恶性肿瘤增强值相比有显著性差异;所有炎症结节,２３例恶性肿瘤及１例结核球呈全部强化型,１例恶性肿瘤呈周边强化型,２例结核球呈环形强化,另外２例结核球无明显强化。结论：（１）结节增强值在２０ＨＵ以下提示结核球,２０～６０ＨＵ为恶性结节的一个指标,６０ＨＵ以上高度提示炎症结节。（２）环形强化提示结核球。