Lung nodule enhancement at CT: multicenter study

PURPOSE: To test the hypothesis that absence of statistically significant lung nodule enhancement (< or =15 HU) at computed tomography (CT) is strongly predictive of benignity. MATERIALS AND METHODS: Five hundred fifty lung nodules were studied. Of these, 356 met all entrance criteria and had a diagnosis. On nonenhanced, thin-section CT scans, the nodules were solid, 5-40 mm in diameter, relatively spherical, homogeneous, and without calcification or fat. All patients were examined with 3-mm-collimation CT before and after intravenous injection of contrast material. CT scans through the nodule were obtained at 1, 2, 3, and 4 minutes after the onset of injection. Peak net nodule enhancement and time-attenuation curves were analyzed. Seven centers participated. RESULTS: The prevalence of malignancy was 48% (171 of 356 nodules). Malignant neoplasms enhanced (median, 38.1 HU; range, 14.0-165.3 HU) significantly more than granulomas and benign neoplasms (median, 10.0 HU; range, -20.0 to 96.0 HU; P < .001). With 15 HU as the threshold, the sensitivity was 98% (167 of 171 malignant nodules), the specificity was 58% (107 of 185 benign nodules), and the accuracy was 77% (274 of 356 nodules). CONCLUSION: Absence of significant lung nodule enhancement (< or = 15 HU) at CT is strongly predictive of benignity.     

CT of the pulmonary nodule: a cooperative study

To evaluate the role of computed tomography (CT) in the investigation of pulmonary nodules, a special reference phantom that enabled CT densitometric measurements independent of variations between scanners and patients was used in ten institutions. A total of 384 nodules not considered calcified by conventional methods were examined; 118 (31%) proved to be benign, and in 65 of these (55%), unsuspected calcification was demonstrated. In 28 of the 65, definite calcification could be identified on thin-section CT scans by simple inspection of the scans at narrow windows. In the remaining 37, presence of calcification could not be clearly established without comparison with the reference CT number from the calibration phantom. CT was most effective in establishing the benignancy of nodules 3 cm or less in diameter and those with discrete or smooth margins. CT rarely yields a confident diagnosis of benign disease in larger nodules and in those with irregular or spiculated borders. After review of prior spot radiographs, low kilovolt peak spot radiographs, and conventional tomograms, the authors conclude that thin-section CT aided by a reference phantom in equivocal cases should be an integral part of the diagnostic approach to the pulmonary nodule.     

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.     

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.     

Solitary pulmonary nodules: comparison of classification with standard, thin-section, and reference phantom CT

Standard, thin-section, and reference phantom computed tomography (CT) were performed to evaluate 75 consecutive patients with solitary pulmonary nodules. Follow-up was available for 62 nodules in 59 patients; 53 of the nodules were benign and nine were malignant. Twenty-one of the 62 nodules were assessed as benign with thin-section CT, while 33 of the 62 nodules were assessed as benign with reference phantom CT. Two of the nodules classified as benign with both thin-section and reference phantom CT proved to be malignant (a peripheral, ossified carcinoid and a 3.5-cm-diameter calcified carcinoma). The sensitivity of reference phantom CT (58%) for classification of benign nodules was higher than the sensitivity of thin-section CT (36%). The sensitivity of standard CT was lowest (12%). The presence of fat at thin-section CT was a reliable criterion for benignancy in six hamartomas. While both thin-section and reference phantom CT were useful in the identification of benign pulmonary nodules, reference phantom CT increased sensitivity by 22% compared with thin-section CT.     

Lung nodules: dual-kilovolt peak analysis with CT--multicenter study

PURPOSE: To test the following hypothesis: The greater the increase in the mean computed tomographic (CT) number of a radiologically indeterminate lung nodule from the CT number on a 140-kVp CT image to that on an 80-kVp CT image, the more likely the nodule is benign (ie, contains calcium). MATERIALS AND METHODS: Two hundred forty indeterminate lung nodules were prospectively studied at four institutions: Mayo Clinic Scottsdale, Ariz (n = 160); Mayo Clinic Rochester, Minn (n = 50); Shiga Health Insurance Hospital, Otsu, Japan (n = 25); and Duke University Medical Center, Durham, NC (n = 5). Of the 240 nodules, 157 met the entrance criteria for this study and had a diagnosis. All nodules included were solid, 5-40-mm diameter, relatively spherical, homogeneous, and without visible evidence of calcification or fat. Each nodule was evaluated by using 3-mm-collimation, nonenhanced CT scans with both 140- and 80-kVp x-ray beams. RESULTS: There were 86 (55%) benign and 71 (45%) malignant nodules. The median increase in the nodule mean CT number from the CT number on 140-kVp images to that on 80-kVp images was 2 HU for benign nodules and 3 HU for malignant nodules. This difference was not statistically significant. The area under the receiver operating characteristic curve was 0.505. CONCLUSION: Dual-kilovolt peak analysis with current CT technology does not appear to be helpful in the identification of benign lung nodules.     

Distinguishing benign from malignant pulmonary nodules with helical chest CT in children with malignant solid tumors

PURPOSE: To retrospectively assess whether computed tomographic (CT) findings can indicate the benign or malignant nature of pulmonary nodules in pediatric patients with malignant solid primary tumors. MATERIALS AND METHODS: With institutional review board approval, waived parental and patient consent, and HIPAA compliance, the authors determined the incidence of malignancy among 81 pulmonary nodules that were sampled at biopsy within 3 weeks after chest CT (January 1999 to September 2003) in 41 young patients with malignant solid tumors. Three radiologists independently and retrospectively reviewed these scans and the available previously obtained scans, classifying nodules as benign, malignant, or indeterminate on the basis of their number, unilateral versus bilateral distribution, size, margins (indistinct vs distinct), calcification, growth, and associated adenopathy. These classifications were compared with nodule histologic type, and interreviewer agreement was assessed. RESULTS: The median patient age was 14.8 years (mean, 13.7 years; range, 5-21 years). Twenty-four of the 41 patients (58%) had at least one biopsy-proved malignant nodule. Four (10%) patients had both benign and malignant nodules; 17 (42%) had only benign nodules. Reviewer 1 classified 65% (39 of 60) of nodules correctly; reviewer 2, 57% (37 of 65); and reviewer 3, 67% (43 of 64). Interreviewer agreement was slight to moderate (kappa /= .32). CONCLUSION: The frequency of benign nodules and the inconsistency of predictions based on CT features suggest the need for better predictors of pulmonary nodules being malignant or benign, so as to reduce unnecessary thoracotomy in pediatric patients with solid malignancy. .     

Pulmonary nodules studied by computed tomography

The authors analyzed 177 pulmonary nodules using thin-section computed tomography (CT), calculating the representative CT number (RCT#) from a computer printout. None of the 96 malignant nodules had an RCT# greater than 151 H. Of the 81 benign nodules, 14 were shown to be calcified by conventional radiography and had an RCT# ranging from 763 and 1,023 H. Thirty had an RCT# greater than 200 H; this included 24 which showed no calcification on conventional tomograms. The remaining 37 benign nodules had an RCT# less than 200 H; 6 of them were hamartomas, including 2 which were diagnosed as such due to their fat content.     

^18F-FDGPET／CT影像特征对甲状腺结节的诊断效能

目的研究甲状腺结节^18F-FDGPET／CT影像特征对甲状腺结节良恶性的鉴别诊断效能。方法回顾性研究68例[男24例,女44例,平均年龄（52．8±10．58）岁]2006年1月至2012年12月间经PET／CT检查发现甲状腺结节且有术后病理结果的患者,分析其PET／CT图像特征并获得特征参数,包括结节边界清晰度、密度均匀性、钙化情况、包膜情况、平均CT值、结节大小及SUVmax。以术后病理结果为“金标准”,采用Mann-Whitney u检验、x^2检验及ROC曲线对各参数的诊断效能进行统计分析。结果68例患者中,病理结果显示恶性18例,良性50例。结节密度是否均匀、有无钙化灶、有无包膜对于甲状腺结节良恶性鉴别均无统计学意义（x^2=0．21、0．01、0．43,均P〉0．05）,结节平均CT值及结节大小亦无鉴别意义（均AUC〈0．5）。结节边界是否清晰对良恶性结节鉴别有统计学意义（x^2=8．06,P〈0．05）,其诊断灵敏度、特异性及准确性分别为55．6％（10／18）、80．0％（40／50）和73．5％（50／68）。良性结节SUVmax为3．16±1．84,恶性结节SUVmax为8．53±7．09,差异有统计学意义（u=-4．281,P〈0．01）。以SUVmax为评价指标,其ROC的AUC为0．841（95％CI：0．726—0．955）,最大约登指数（0．562）对应SUVmax为4．25,其诊断灵敏度、特异性及准确性分别为72．2％（13／18）、84．0％（42／50）和80．9％（55／68）。结论可依据^18F—FDGPET／CTSUVmax对甲状腺结节良恶性进行判断,但同机CT影像特征价值有限。     

Dynamic computed tomography in solitary pulmonary nodules

OBJECTIVE: To evaluate the utility of dynamic computed tomography (CT) imaging in the management of solitary pulmonary nodules. METHODS: We examined solitary pulmonary nodules in 45 patients. The nodules included in the study were solid, homogenous, and spherical or oval-shaped in precontrast images. Nodules that had calcification or fat density were excluded from the study. We were not able to obtain clinical or pathological diagnosis of the nodules in 23 patients, and we excluded these patients from statistical analysis. Patients were examined with 2-mm collimation and 1-mm reconstruction interval. Computed tomography examinations were done before and after injection of contrast material. Computed tomography scans of the nodule were obtained in the first, second, third, fourth, and fifth minutes after contrast injection. RESULTS: The malignancy prevalence was 40%. The mean enhancement of malignant nodules were significantly higher than the benign ones. Also, the peak attenuation value obtained after the administration of contrast material was 82.44 +/- 19.56 HU in malignant lesions and 54 +/- 23.10 HU in benign ones, with statistical significance (P = 0.006). Using enhancement values greater than 15 HU as a threshold for malignancy, the calculated sensitivity, specificity, positive and negative predictive values, and accuracy of the dynamic CT examination were 100%, 69.2%, 69.2%, 100%, and 81%, respectively. CONCLUSION: Dynamic CT imaging demonstrates significantly greater enhancement in malignant nodules than in benign ones. Lung nodule enhancement of 15 HU or less strongly indicates benignity.     

对甲状腺良性结节高频超声误诊原因的初步探讨

目的:探讨各不同病理类型良性甲状腺结节的超声声像图表现;探讨超声在甲状腺结节良、恶性鉴别诊断中,出现假阳性的主要原因及可行的避免误诊的方法。方法:经手术病理证实的172例甲状腺良性结节,42例甲状腺微灶癌和26例甲状腺乳头状癌。对比分析超声误诊的43例良性结节、42例甲状腺微灶癌和26例甲状腺乳头状癌的声像图表现、对甲状腺结节的钙化模式进行分型,探讨超声误诊的主要原因。结果:甲状腺恶性结节内伴发钙化的比例明显高于甲状腺良性结节。甲状腺结节不伴发钙化组的诊断准确性明显高于伴发钙化组。结论:结节内伴发的钙化灶已成为影响高频超声良恶性鉴别诊断准确性,尤其是特异性的主要原因。严格定义III型钙化的诊断标准,可以减少部分的假阳性的发生。     

18F-FDG PET/CT对不同大小孤立性肺结节的诊断价值

目的 评价18F-脱氧葡萄糖(FDG) PET/CT对不同大小范围孤立性肺结节(SPN)良恶性鉴别诊断的价值.方法 从全国拥有PET/CT的10家医院筛选出已经获得病理学检查结果的SPN病例,收集诊断CT、PET/CT和病理检查结果以及标准摄取值(SUV)、结节大小等资料.诊断CT、PET/CT结果为肺癌、肺癌可能性大、肺癌可能者为阳性;结果为良性病变、良性可能性大、良性可能者为阴性;难以确定阳性和阴性者为不确定.采用SPSS 10.0软件对资料进行分析.结果 120个(120例)SPN中良性结节28个,恶性结节92个.直径或(长径+短径)/2≤1.0cm的结节17个,恶性病变9个;1.1～2.0cm 57个,恶性病变占75.44%;2.1～3.0cm 46个,恶性病变占86.96%.28个良性结节SUV最大值(SUVmax)的平均值为4.5±4.9, SUV平均值(SUVmean)的平均值为2.9±3.6;92个恶性结节SUVmax平均值为6.7±4.2, SUVmean平均值为4.9±3.6;良性结节的SUV显著低于恶性结节的SUV.无论良性还是恶性结节,随着结节的增大,SUV升高.诊断CT对结节良恶性鉴别的灵敏度为78.26%,特异性3/8,准确性72.22%; PET/CT灵敏度为94.51%,特异性64.00%,准确性87.93%.结论 18F-FDG PET/CT在SPN鉴别诊断中具有较高的灵敏度、特异性和准确性,优于诊断CT;结节大小是判断SPN良恶性的重要指标,直径或(长径+短径)/2＞2.0cm的结节,恶性可能性约为87%; SUV可以作为鉴别诊断的依据,但鉴于良性结节SUVmean的平均值为2.9±3.6,界值2.5仅供参考,尤其是对于≤1.0cm的结节.     

Radiologische Abklärung inzidenteller pulmonaler Rundherde

Since the widespread use of computed tomography (CT), the detection of pulmonary nodules has considerably increased and has become part of the daily clinical routine. In the evaluation of pulmonary nodules, malignant nodules have to be differentiated from benign pulmonary nodules with a high level of confidence. The diagnostic approach for pulmonary nodules depends on the pretest probability for malignancy. For indeterminate pulmonary nodules <8 mm, non-contrast CT observational follow-up is recommended and depending on the size and pretest probability for malignancy, follow-up CT intervals range from 3 to 12 months. For indeterminate pulmonary nodules >8 mm, management is based on patient surgical risk and pretest probability for malignancy. Either CT follow-up alone, 18-fluorodeoxyglucose-positron emission tomography (FDG-PET) or non-surgical biopsy for tissue diagnosis are utilized to evaluate the lesions. For pulmonary nodules with a high pretest probability for malignancy, surgical resection is recommended unless specifically contraindicated.     

彩色多普勒超声诊断良恶性甲状腺结节的参考价值

目的分析良、恶性甲状腺结节的彩色多普勒超声表现,以提高超声诊断和鉴别诊断良、恶性甲状腺结节的价值。方法回顾性分析经手术、病理明确诊断的157个良、恶性甲状腺结节的彩色多普勒超声表现,良、恶性结节的形态、回声、钙化特点、彩色多普勒血流图血流信号分布等。结果157个甲状腺结节经病理诊断,其中 90个为良性结节,67个为恶性结节;本组病例彩色多普勒超声检查的特异性为92.2%,敏感性为80.6%,诊断符合率为87.2%;彩色多普勒超声图像显示甲状腺良、恶性结节的形态、边界、包膜、回声、血流信号分布、内部钙化情况、血流阻力指数值比较,差异比较均具有统计学意义（P<0.05）。结论彩色多普勒超声可诊断甲状腺病变,依据重要的参考指标,可评价甲状腺结节的良、恶性。     

Solitary pulmonary nodules: CT assessment

Computed tomography (CT) was used to examine 634 solitary pulmonary nodules (SPNs). Each lesion was assessed as benign or indeterminate on the basis of CT criteria. Benign nodules made up 44% of all SPNs and 58% of the 431 that were 2 cm or less in diameter. All malignant SPNs were assessed as indeterminate, and adenocarcinoma (42%) was the most common primary malignancy. A total of 176 (63% of benign SPNs) were correctly assessed as benign by CT. Ninety SPNs assessed as diffusely calcified were not so identified by conventional tomography at outside institutions. An SPN can be reliably assessed by CT as benign if it exhibits high attenuation values, exceeding a critical level and distributed diffusely throughout a CT section through the center of the lesion and a well-defined edge. Although 38 of 283 (13.4%) primary lung cancers contained localized calcification, there was no significant overlap with the diffuse calcification of benign lesions. Central carcinoid tumors may contain focal ossification, but such lesions may be recognized by noting the proximity of larger bronchi. Assessment of SPNs by CT is most effective for lesions 2.0 cm or less in diameter. For larger lesions, the frequency of benign disease was decreased (14.3% of 203), as was the percentage of benign SPNs correctly assessed as benign by CT (37.9%).     

探讨肺结节内钙化密度与钙化征象的临床意义

目的：研究肺结节内钙化密度与钙化征象对肺结节良恶性预判的性能。方法经病理或随访证实的肺结节240例（良性70例,恶性170例）。利用最大方差和阈值生长法提取肺结节内具有钙化点和钙化密度的像素,并计算每个钙化点的面积（AreaCa）及面积比（Ar）、同一层面内钙化点的总面积（S）及钙化总面积比（Sr）、同一层面内具有钙化密度的总面积（Cs）及钙化密度面积比（Csr）。结果含有钙化密度的结节明显多于含钙化点的结节（49vs26,χ2＝8．360,P＝0．004）,这一现象在恶性结节中尤为突出（良性23vs16;恶性26vs10）;良性肺结节钙化点和钙化密度的面积均大于恶性（P＝0．000）;以钙化点（AreaCa、S、Ar、Sr）对肺结节良恶性预判的诊断性能优秀（Az＝0．906）,以钙化密度（Cs、Csr）对肺结节性质预判的诊断性能中等（Az＝0．727,0．742）。结论在计算机辅助诊断研究中,借鉴医师经验,对肺结节的CT征象直接进行提取、挖掘,或有助于肺结节影像诊断的确立。     

Image analysis methods for solitary pulmonary nodule characterization by computed tomography.

Computer software was designed for classifying solitary pulmonary nodules (SPNs) into benign and malignant from their CT images, using image analysis methods. The system made use of three features, computed from the CT density matrix of the SPN, and a class-discriminating algorithm. System evaluation was performed on 51 histologically confirmed SPNs of indeterminate CT diagnosis. Overall classification accuracy in distinguishing benign and malignant SPNs was 90.2%, while 83.3% of the benign and 93.9% of the malignant SPNs were correctly classified. The proposed system may be of value to the radiologist in assessing the probability of malignancy in patients with a solitary pulmonary nodule.     

Management of an incidentally discovered pulmonary nodule

The incidental finding of a pulmonary nodule on computed tomography (CT) is becoming an increasingly frequent event. The discovery of such a nodule should evoke the possibility of a small bronchogenic carcinoma, for which excision is indicated without delay. However, invasive diagnostic procedures should be avoided in the case of a benign lesion. The objectives of this review article are: (1) to analyze the CT criteria defining benign nodules, nodules of high suspicion of malignancy and indeterminate nodules, (2) to analyze the diagnostic performances and limitations of complementary investigations requested to characterize indeterminate lung nodules, (3) to review the criteria permitting to assess the probability of malignancy of indeterminate nodules and (4) to report on the new guidelines provided by the Fleischner Society for the management of small indeterminate pulmonary nodules, according to their prior probability of malignancy.     

双能CT对孤立性肺结节的诊断价值

目的:探讨双能CT对孤立性肺结节(SPN)的诊断价值.方法:采用双能CT(管电压为80和140kVp)对水模、体模、47例平扫CT无明显钙化的SPN(恶性31例,良性16例)进行扫描,测量其CT值变化,计算病灶内钙质含量,比较良恶性SPN的CT值变化及钙质含量.结果:良性SPN的CT值变化中位数为5HU,恶性SPN为4...     

CT of the solitary pulmonary nodule

Computed tomography (CT) with thin sections (2-5 mm) was used to assess tissue density in 91 apparently noncalcified pulmonary nodules in 88 patients. The study included 45 primary lung malignancies and 13 metastases proven by subsequent lung biopsy or thoracotomy. There were 33 benign lesions of which 13 were biopsy proven. The other 20 nodules were presumed benign on the basis of serial radiography showing no growth. A representative CT number based on the 32 most dense voxels was calculated for each lesion. For the primary malignancies, the mean representative CT number was 92 H, with a standard deviation of 18 H. The highest representative CT number for any malignant lesion was 147 H. Of the 33 benign lesions, 20 had a representative CT number of 164 H or greater. It is presumed that nodules with representative CT numbers of 164 H are benign, and that diffuse calcification likely accounts for the higher CT number of some benign lesions. CT has proven to be more objective and more sensitive than standard tomography in assessing the density of pulmonary nodules.