Noncalcified Nodules Research Articles

The Danish Randomized Lung Cancer CT Screening Trial—Overall Design and Results of the Prevalence Round

Lung cancer screening with low dose computed tomography (CT) has not yet been evaluated in randomized clinical trials, although several are underway. In The Danish Lung Cancer Screening Trial, 4104 smokers and previous smokers from 2004 to 2006 were randomized to either screening with annual low dose CT scans for 5 years or no screening. A history of cigarette smoking of at least 20 pack years was required. All participants have annual lung function tests, and questionnaires regarding health status, psychosocial consequences of screening, smoking habits, and smoking cessation. Baseline CT scans were performed in 2052 participants. Pulmonary nodules were classified according to size and morphology: (1) Nodules smaller than 5 mm and calcified (benign) nodules were tabulated, (2) Noncalcified nodules between 5 and 15 mm were rescanned after 3 months. If the nodule increased in size or was larger than 15 mm the participant was referred for diagnostic workup. At baseline 179 persons showed noncalcified nodules larger than 5 mm, and most were rescanned after 3 months: The rate of false-positive diagnoses was 7.9%, and 17 individuals (0.8%) turned out to have lung cancer. Ten of these had stage I disease. Eleven of 17 lung cancers at baseline were treated surgically, eight of these by video assisted thoracic surgery resection. Screening may facilitate minimal invasive treatment and can be performed with a relatively low rate of false-positive screen results compared with previous studies on lung cancer screening.

Low-Dose CT Screening for Lung Cancer: Trial and Error?

After the disappointing experience with lung cancer screening studies based on chest x-ray and/or sputum cytology several decades ago, great expectations are now in place on screening with modern low-dose spiral computed tomography (LDSCT) scan. The prevalence data of one of these randomized studies is reported in this issue of our journal.1 The definition of screening—adapted from Stedman’s Concise dictionary—consists of an examination of a group of usually asymptomatic individuals to detect those with a high probability of having a given disease, typically by means of an inexpensive, safe, and well-performing diagnostic test.2 To reach the real goal—reduction of lung cancer related mortality—four conditions need to be in place: a sensitive test for detection of small lesions; small lesions need to be associated with truly early stage disease; an effective treatment is available for these lesions; and acceptable morbidity and cost of the screening tool. Screening for lung cancer by LDSCT has been studied extensively in the past decade, and it looks like this might become the long awaited tool. Looks like, because until today, all the available data have been gathered from many—some even very large—cohort studies, but not yet from large randomized controlled trials. These nonrandomized studies show promising results. In the I-ELCAP trial in asymptomatic smokers or past smokers, for instance, 85% of lung cancers were detected in stage I, and the estimated 10-year survival rate of patients whose stage I lung cancer was removed by surgery was 92%.3 This suggests that LDSCT is a sensitive tool that is able to detect small lesions associated with truly early stage, for which an effective therapy is available. This does not prove, however, that the strategy results in a reduction of lung cancer related mortality. This evidence can only come from the eagerly awaited results from two large randomized controlled trials that are currently running, the American National Lung Screening Trial, started in 2002, and the Dutch-Belgian Nederlands-Leuvens Longkanker Screening Onderzoek (NELSON) trial, started in 2003.4,5 The long-term postscreening follow-up on the primary end point of reduction of lung cancer mortality in participants in the National Lung Screening Trial and the NELSON trial is planned to end in 2009 and 2014, respectively. Until then, the “pro and con debate” on CT screening for lung cancer will probably remain a “battle over lung scans.”6,7 Some other, smaller RCTs have been setup in Italy, France, and in Denmark, the Danish randomized lung cancer CT screening trial (DLCST), whose first round or prevalence CT results are reported now.1 This DLCST has been designed in accordance with the NELSON trial to allow pooling of both study data together once both screening trials will have been finished. The combined data on lung cancer-specific mortality of around 20,000 included individuals will then give these two CT lung cancer screening trials an 80% power to show a lung cancer mortality reduction of at least 25%.5 Although waiting for the final results of these trials’ follow-up period by the year 2014, it is interesting to compare the first round CT screening results of the DLCST to the previously reported results from other series. The lung cancer detection rate of 0.83% (17 cases of lung cancer in 2052 participants) is lower than previously reported in nonrandomized CT screening trials. As pointed out by the authors, this result is not easily explainable at this time, and results of the lung cancer prevalence in their control group

Commercially Available Computer-Aided Detection System for Pulmonary Nodules on Thin-Section Images Using 64 Detectors-Row CT: Preliminary Study of 48 Cases

Most studies of computer-aided detection (CAD) for pulmonary nodules have focused on solid nodule detection. The aim of this study was to evaluate the performance of a commercially available CAD system in the detection of pulmonary nodules with or without ground-glass opacity (GGO) using 64-detector-row computed tomography compared to visual interpretation. Computed tomographic examinations were performed on 48 patients with existing or suspicious pulmonary nodules on chest radiography. Three radiologists independently reported the location and pattern (GGO, solid, or part solid) of each nodule candidate on computed tomographic scans, assigned each a confidence score, and then analyzed all scans using the CAD system. A reference standard was established by a consensus panel of different radiologists, who found 229 noncalcified nodules with diameters > or = 4 mm. True-positive and false-positive results and confidence levels were used to generate jackknife alternative free-response receiver-operating characteristic plots. The sensitivity of GGO for 3 radiologists (60%-80%) was significantly higher than that for the CAD system (21%) (McNemar's test, P < .0001). For overall and solid nodules, the figure-of-merit values without and with the CAD system were significantly different (P = .005-.04) on jackknife alternative free-response receiver-operating characteristic analysis. For GGO and part-solid nodules, the figure-of-merit values with the CAD system were greater than those without the CAD system, indicating no significant differences. Radiologists are significantly superior to this CAD system in the detection of GGO, but the CAD system can still play a complementary role in detecting nodules with or without GGO.

Human chorionic gonadotropin production by a benign lung nodule

Ectopic hormone production by a neoplasm is defined as secretion of a hormone by cells not normally a source of that hormone. This relationship is a recognized phenomenon that assists in diagnosis of disease and provides a marker for monitoring treatments. Ectopic human chorionic gonadotropin (hCG) is associated with neoplasms originating in the lungs, gastrointestinal tract, cervix, and bladder. Recent evidence recognizes 3 variants of hCG, with nontrophoblastic tumors producing the free beta-subunit variant. This variant influences cancer cell growth andmay be valuable as a poor prognostic marker [1]. Approximately 15%of lung tumorsdemonstrate detectable hormone [2], and evidence suggests that paraneoplastic lung tumors are often more resistant to treatment, have a poor prognosis, and are rapidly fatal [3]. This report presents an individual with a benign indolent lung nodule secreting beta-hCG. Final pathology revealed an inflammatory myofibroblastic tumor (IMT). This type of tumor is rare, accounting for 0.4%–1.0% of all lung tumors; they are often asymptomatic, but may present with cough, hemoptysis, or dyspnea. IMTs are low-grade tumors, histologically composedof inflammatoryspindle cells thatoftengrowlocallyandslowly [4]. A 42-year-old patient (para 0) presented after a positive homepregnancy test. Medical history was significant for an incidental lung lesion detected in 1989bychestX-ray followingapositivePPD.At that time, evaluation revealed a 2-cm, well-rounded, noncalcified lesion in the right lower lobe with no associated adenopathy. A biopsy (with preoperative evaluation showing negative hCG) was consistent with pseudotumor; no further treatment was advised. Several chest X-rays since 1989 showed a stable lesion. Obstetricgynecology history was noncontributory, with menarche at 13 years, regular periods, and no history of infertility. Upon presentation after positive pregnancy test, the patient reported only fatigue and shortness of breath upon exertion; she denied cough, sputum production, chest pain, fever, chills, or vaginal bleeding. Her last menstrual period was 51/2 weeks prior, and beta-hCG quantitative value (beta-quant) was 8961 mIU/mL. Multiple ultrasounds showed no intrauterine, molar, or ectopic pregnancy. Diagnostic laparoscopy confirmed no ectopic pregnancy; dilation and curettage revealed no gestational trophoblastic disease. The patient was given methotrexate; however, beta-quant continued to rise to 20 648mIU/mL over 5 days, and shewas referred togynecologic oncology.Gynecologic oncologyevaluated and referred her to thoracic surgery for assessment of her lung nodule. Lung exam was normal, and chest CT and positron emission tomography (PET) demonstrated a solitary, round, noncalcified right lower lobe nodule 1.2 cm (Fig. 1) with moderate uptake on PET. The patient underwent fiberoptic bronchoscopy and right thoracoscopic lower lobe wedge resection revealing a solitary, firm, solid lesion within the right lower lobe. Pathology revealed a noninvasive, 1-cm spindle cell lesion consistent with IMT. Postoperative beta-quant decreased steadily reaching zero approximately 3 weeks postoperatively, and the patient resumed regular periods. Beta-hCG secreting lung cancer is too rare to be a useful tumor marker by pulmonologists; however, it is critical that obstetriciangynecologists recognize the wide range of sources of beta-hCG production and refer patients for further evaluation after excluding common obstetric etiologies. The present case demonstrates the importance of considering all lung nodules as a source of ectopic betahCG; however, it is unclearwhether this case signifies a change in nature of the tumor, or a newfindingnot previously clinically evident. Given the recent evidence on multiple variants of hCG, further detailed analysis of hCG may be warranted in determining malignant potential of nontrophoblastic tumors. Physicians should be aware of the malignant nature ofmost beta-hCG secreting tumors and consider the potential for transformation of benign appearing nodules to more aggressive tumors.

The Prevalence of Incidental Findings on Abdominal Computed Tomography Scans of Trauma Patients

Abdominal computed tomography scanning (AbdCTS) is the standard of care in the evaluation of blunt trauma patients. The liberal use of AbdCTS coupled with advancing imaging technology often results in the detection of incidental findings. We sought to characterize the incidence and prevalence of such findings, describe the lesions most frequently seen on AbdCTS performed on patients admitted to a Level I trauma center, and develop a plan for follow-up through our performance improvement process. AbdCTS reports of all admissions to a Level I trauma center between January 2000 and December 2002 were reviewed. Incidental findings identified were classified into benign anatomic variants, benign pathologic lesions, and pathologic lesions requiring further work-up. A total of 3,113 patients were evaluated by AbdCTS during this time period. There were 1474 incidental findings in 1,103 patients. Seventy-five percent of patients with incidental lesions had no traumatic findings. Benign anatomic variants were present in 1.8%, benign pathologic findings in 27.5%, and pathologic findings requiring work-up in 6.1%. Congenital renal anomalies and duplicate inferior vena cava were the most common benign anatomical findings. Renal and hepatic cysts were the most frequent benign lesions and non-calcified pulmonary nodules and adrenal masses were the pathologic lesions most commonly seen. Incidental findings are seen in up to 35% of trauma AbdCTS. No concomitant traumatic injuries are present in up to 75% of these patients. Protocols for appropriate intervention or arrangements for follow-up care need to be incorporated into the care of the trauma patients.

Smooth or Attached Solid Indeterminate Nodules Detected at Baseline CT Screening in the NELSON Study: Cancer Risk during 1 Year of Follow-up

To retrospectively determine whether baseline nodule characteristics at 3-month and 1-year volume doubling time (VDT) are predictive for lung cancer in solid indeterminate noncalcified nodules (NCNs) detected at baseline computed tomographic (CT) screening. The study, conducted between April 2004 and May 2006, was institutional review board approved. Patient consent was waived for this retrospective evaluation. NCNs between 5 and 10 mm in diameter (n = 891) were evaluated at 3 months and 1 year to assess growth (VDT < 400 days). Baseline assessments were related to growth at 3 months and 1 year by using chi(2) and Mann-Whitney U tests. Baseline assessments and growth were related to the presence of malignancy by using univariate and multivariate logistic regression analyses. At 3 months and at 1 year, 8% and 1% of NCNs had grown, of which 15% and 50% were malignant, respectively. One-year growth was related to morphology (P < .01), margin (P < .0001), location (P < .001), and size (P < .01). All cancers were nonspherical and purely intraparenchymal, without attachment to vessels, the pleura, or fissures. In nonsmooth unattached nodules, a volume of 130 mm(3) or larger was the only predictor for malignancy (odds ratio, 6.3; 95% confidence interval [CI]: 1.7, 23.0). After the addition of information on the 3-month VDT, large volume (odds ratio, 4.9; 95% CI: 1.2, 20.1) and 3-month VDT (odds ratio, 15.6; 95% CI: 4.5, 53.5) helped predict malignancy. At 1 year, only the 1-year growth remained (odds ratio, 213.3; 95% CI: 18.7, 2430.9) as predictor for malignancy. In smooth or attached solid indeterminate NCNs, no malignancies were found at 1-year follow-up. In nonsmooth purely intraparenchymal NCNs, size is the main baseline predictor for malignancy. When follow-up data are available, growth is a strong predictor for malignancy, especially at 1-year follow-up.

Computed Tomography-detected Noncalcified Pulmonary Nodules: A Review of Evidence for Significance and Management

Our purpose was to review the reported behavior and malignant risk of small noncalcified pulmonary nodules detected by computed tomography (CT). A review of published clinical guidelines and studies using CT scan for lung cancer screening was performed. Small pulmonary nodules are found in 5 to 60% of patients in published CT screening studies. The detection rate is influenced by the CT scan technique used, definition of a significant nodule, and the population of subjects screened. There is limited published systematic longitudinal observation of all nodules of any size. The malignancy rate of small nodules detected in smokers is likely less than 1 to 2%, and predictors of malignancy include semisolid appearance, diameter greater than or equal to 10 mm or persistent growth on greater than or equal to two CT scans. There is a wide variation in the performance of positron emission tomography (PET) scan in screening detected lung cancers. In summary, multidetector row CT detects greater than or equal to 1 nodule in most high-risk patients. The risk of malignancy for a single nodule appears to be low, but is increased by serial growth, diameter greater than or equal to 10 mm, and semisolid appearance. The role of PET in evaluating these nodules needs further exploration. Serial follow-up for 24 months in a high-risk cohort appears reasonable based on present data, but further longitudinal information is required.

Usefulness of concurrent reading using thin-section and thick-section CT images in subcentimetre solitary pulmonary nodules

To evaluate the differences in the characterization and recommendation for follow-up of subcentimetre solitary pulmonary nodules (SSPNs) between 5 and 1mm section CT, and to compare the assessments generated by four radiologists Five hundred and twenty-nine patients who had SSPNs on chest CT reconstructed using both 5 and 1mm sections were enrolled. Two image subsets of 5 and 1mm CT images of each nodule were interpreted independently by four radiologists. Nodule size, consistency (solid, partly solid, non-solid), the presence of calcification, and recommendations for follow-up were evaluated. If a non-calcified solid nodule was confirmed using CT, recommendation for follow-up was based on Fleischner Society guidelines. Data assessed by each radiologist were compared, and interobserver agreements were determined using the intraclass correlation coefficients and kappa value. Using 1mm CT images, the nodule sizes were significantly larger than on 5mm CT images (paired t-test, p<0.01). The presence of calcification and nodule consistency were significantly different between 5 and 1mm CT images (McNemar test for the presence of calcification, p<0.01; Wilcoxon signed test for nodule consistency, p<0.01). On 1mm CT images there was significantly higher agreement regarding nodule consistency than on 5mm CT (kappa=0.78 and 0.67, respectively). Concurrent use of thin-section and thick-section CT can provide more accurate nodule assessment and higher interobserver agreement in SSPN.

Computer-aided detection of lung nodules on multidetector row computed tomography using three-dimensional analysis of nodule candidates and their surroundings

We have been developing a computer-aided detection (CAD) system for lung nodules on multidetector row computed tomography (MDCT). The scheme for nodule detection in this system is featured by three-dimensional analysis of nodule candidates [corrected] and their surroundings, which is designed to discriminate nodules from blood vessels. The purpose of this study was to evaluate the CAD system. MDCT images from 30 patients with lung nodules were read twice, 3 weeks apart by a chest radiologist to detect noncalcified nodules of > or = 4 mm. The first reading was without CAD, and the second reading was with CAD. Based on the reference standard later determined by another chest radiologist, the sensitivity of the former chest radiologist without or with CAD was obtained; the sensitivity and false-positive rate of the system alone were also obtained. The reference standard consisted of 66 nodules. The sensitivity of the chest radiologist was 77% (51/66) without CAD and 91% (60/66) with CAD, showing a significant improvement. The CAD system alone showed a sensitivity of 79% (52/66) with the false-positive rate of 4.5 per patient. Although preliminary, these results indicate the efficacy of the CAD system.

Incidental Pulmonary Nodules on Cardiac Computed Tomography: Prognosis and Use

Background Small asymptomatic lung nodules are found frequently in the course of cardiac computed tomography (CT) scanning. However, the utility of assessing and reporting incidental findings in healthy, asymptomatic subjects is unknown. Methods The sample comprised 1023 60- to 69-year-old subjects free of clinical cardiovascular disease and cancer who participated in the Atherosclerotic Disease, VAscular functioN and genetiC Epidemiology Study. All subjects underwent cardiac CT for determination of coronary calcium between 2001 and 2004, and the first 459 subjects were assessed for incidental pulmonary findings. We used health plan clinical databases to ascertain 24-month health care use and clinical outcomes. Results Noncalcified pulmonary nodules were reported in 81 of 459 subjects (18%). Chest CT was performed on 78% of participants in the 24 months after notification, compared with 2.5% in the previous 24 months. Chest x-ray use increased from 28% to 49%. The mean number of chest CT scans per subject was 1.3 (range, 0-5). Although no malignant lesions were diagnosed in the group who had pulmonary findings read, 1 lung cancer case was diagnosed in the group who did not have lung findings read. Among the 63 participants followed up by CT, the original lesion was not identified in 22 participants (35%), the lesion had decreased or remained stable in 39 participants (62%), and there was interval growth in 2 participants (3%). Conclusion Reporting noncalcified pulmonary nodules resulted in substantial rescanning that overwhelmingly revealed resolution or stability of pulmonary nodules, arguing for benign processes.

Advantages of multidetector-row CT with multiplanar reformation in guiding percutaneous lung biopsies

This study aimed to assess the usefulness of multiplanar reformations (MPR) during multidetector-row computed tomography (MDCT)-guided percutaneous needle biopsy of lung lesions difficult to access with the guidance of the native axial images alone owing to overlying bony structures, large vessels or pleural fissures. MDCT-guided transthoracic needle biopsy (TNB) was performed on 84 patients (55 men and 29 women; mean age 65 years) with suspected lung neoplasm by using a spiral MDCT scanner with the simultaneous acquisition of six slices per rotation. We determined the site of entry of the 22-gauge Chiba needle on native axial images and coronal or sagittal MPR images. We took care to ensure the shortest needle path without overlying large vessels, main bronchi, pleural fissures or bony structures; access to the lung parenchyma as perpendicular as possible to the pleural plane; and sampling of highly attenuating areas of noncalcified tissue within the lesion. Diagnostic samples were obtained in 96% of cases. In 73 patients, lesions appeared as a solid noncalcified nodule <2 cm; 11 lesions were mass-like. In 22, the biopsy required MPR guidance owing to overlying ribs (18), fissures (2) or hilar-mediastinal location (2). MDCT MPR images allowed sampling of pulmonary lesions until now considered unreachable with axial MDCT guidance because of overlying bony structures (ribs, sternum and scapulae) or critical location (hilar-mediastinal, proximity to the heart or large vessels). Compared with the conventional procedure, the use of MPR images does not increase the rate of pneumothorax or the procedure time.

Radiological diagnosis of small pulmonary nodules detected on low‐dose screening computed tomography

Early detection and treatment of small malignant pulmonary lesions can improve survival; however, screening by CT detects many false positives. This study retrospectively evaluated a protocol for the diagnostic work-up of nodules detected by low-dose CT (LDCT) that are < or = 10 mm in diameter. A health screening programme included LDCT. Lesions detected were allocated to one of four categories: negative, semi-negative, positive and semi-positive. Positive and semi-positive categories included non-calcified nodules without a polygonal shape, and these patients had an initial diagnostic HRCT and were then followed up using high-resolution CT (HRCT) at intervals determined by the characteristics of the lesion on screening LDCT and the initial diagnostic HRCT. There were 275 nodules detected on screening LDCT; 84 patients had lesions classified as positive and 99 as semi-positive. Thirteen nodules detected on screening LDCT were only determined to be polygonal and benign following the diagnostic HRCT. The sensitivity and specificity of the screening CT, when compared with diagnostic HRCT, for determining if nodules should be classified as positive were 100% and 97%. The sensitivity and specificity of the initial diagnostic HRCT for being able to predict lung cancer were 87.5% and 91.7% respectively. Following the detection of a pulmonary lesion on screening LDCT, a diagnostic HRCT is necessary to determine the timing of follow-up HRCT. Diagnostic HRCT is needed to rationalize the screening for lung cancer to reduce the frequency of unnecessary follow-up scans.

The Pittsburgh Lung Screening Study (PLuSS)

The role of computed tomography (CT) screening for lung cancer is controversial, currently under study, and not yet fully elucidated. To report findings from initial and 1-year repeat screening low-radiation-dose CT of the chest and 3-year outcomes for 50- to 79-year-old current and ex-smokers in the Pittsburgh Lung Screening Study (PLuSS). Notified of findings on screening CT, subjects received diagnostic advice from both study and personal physicians. Tracking subjects for up to three years since initial screening, we obtained medical records to document diagnostic procedures, lung cancer diagnoses, and deaths. 3,642 and 3,423 subjects had initial and repeat screening. A total of 1,477 (40.6% of 3,624) were told about noncalcified lung nodules on the initial screening and, before repeat screening, 821 (55.6% of 1,477, 22.5% of 3,642) obtained one or more subsequent diagnostic imaging studies (CT, positron emission tomography [PET], or PET-CT). Tracking identified 80 subjects with lung cancer, including 53 subjects with tumor seen at initial screening. In all, 36 subjects (1.0% of the 3,642 screened), referred for abnormalities on either the initial or repeat screening, had a major thoracic surgical procedure (thoracotomy, video-assisted thoracoscopic surgery [VATS], median sternotomy, or mediastinoscopy) leading to a noncancer final diagnosis. Out of 82 subjects with thoracotomy or VATS to exclude malignancy in a lung nodule, 28 (34.1%) received a noncancer final diagnosis. Forty of 69 (58%) subjects with non-small cell lung cancer had stage I disease at diagnosis. Though leading to the discovery of early stage lung cancer, CT screening also led to many diagnostic follow-up procedures, including major thoracic surgical procedures with noncancer outcomes.

Lung cancer screening with low-dose computed tomography: A non-invasive diagnostic protocol for baseline lung nodules

Indeterminate non-calcified lung nodules are frequent when low-dose spiral computed tomography (LD-CT) is used for lung cancer screening. We assessed the diagnostic utility of a non-invasive work-up protocol for nodules detected at baseline in volunteers enrolled in our single-centre screening trial, and followed for at least 1 year. 5201 high-risk volunteers, recruited over 1 year from October 2004, underwent baseline LD-CT; 4821 (93%) returned for the first repeat LD-CT. Nodules <or=5mm underwent repeat LD-CT at 1 year; nodules 5.1-8mm underwent LD-CT 3 months later; lesions >8mm received combined CT-positron emission tomography (CT-PET). A subset of nodules >8mm was studied by CT with contrast. Protocol failures were delayed diagnosis with disease progression beyond stage I, and negative surgical biopsy. 2754 (53%) volunteers presented one or more non-calcified nodules. Ninety-two lung cancers were diagnosed: 55 at baseline and 37 at annual screening (66% stage I). Among the 37 incident cancers, 17 had a baseline nodule that remained stage I, 7 had a baseline nodule that progressed beyond stage I, and 13 presented a new malignant nodule. Baseline and annual cancers were 79 (1.5%) and 13 (0.2%), respectively. In 15 of 104 (14%) invasive diagnostic procedures, the lesion was benign. Sensitivity, and specificity were 91 and 99.7%, respectively, for the entire protocol; 88 and 93% for CT-PET; and 100 and 59% for CT with contrast. The protocol limits invasive diagnostic procedures while few patients have diagnosis delay, supporting the feasibility of lung cancer screening in high-risk subjects by LD-CT. Nevertheless further optimization of the clinical management of screening-detected nodules is necessary.

Effect of Multiscale Processing in Digital Chest Radiography on Automated Detection of Lung Nodule with a Computer Assistance System

The aim of this study is to evaluate the effect of multiscale processing in digital chest radiography on automated detection of lung nodule with a computer-aided diagnosis (CAD) system. The study involved 58 small-nodule patient cases and 58 normal cases. The 58 patient cases included a total of 64 noncalcified lung nodules up to 15 mm in diameter. Each case underwent an examination with a digital radiography system (Digital Diagnost, Philips Medical Systems), and the acquired image was processed by the following three types of multiscale processing (Unique Image Processing Package, Philips Medical Systems) respectively: (1) standard image from the default processing parameter (structure preference, 0.0), (2) high-pass image with structure preference of 0.4, (3) low-pass image with structure preference of -0.4. The CAD output images were produced with a real-time computer assistance system (IQQAtrade mark-Chest, EDDA Technology). Two experienced chest radiologists established the nodule gold standard by consensus reading according to computed tomography results, and analyzed and recorded the detection of lung nodules and false-positive detections of these CAD output images. For the entire cases involved (each case with three types of different processing), a total of 348 observations were evaluated by the receiver operating characteristic (ROC) analysis. The mean area under the ROC curve (A ( z )) value was 0.700 for the standard images, 0.587 for the high-pass images, and 0.783 for the low-pass images. There were statistically significant A (z) values among these three types of processed images (p < 0.01). Multiscale processing in digital chest radiography can affect the automated detection of lung nodule by CAD, which is consistent with effects from visual inspection.

Lung primary primitive neuroectodermal tumor in an adult patient

A 53-year-old Caucasian male was evaluated for cough and exertional dyspnea. His past medical history was significant for heavy cigarette smoking and recurrent pneumonias. CT scan of the chest performed in January 2007 revealed multiple, sub-centimeter, calcified and non-calcified pulmonary nodules those were stable when compared to a scan done in May of 2005. However, a new 6mm non-calcified nodule was noted in the right lower lobe (Figure 1(A)). In June 2007, a repeat CT scan of the chest demonstrated enlargement of the nodule to a diameter of 2.5 cm (Figure 1(B)). Three weeks later, PET-CT showed high uptake within the mass (standardized uptake value maximum of 15.6) with a new subjacent nodule measuring 1.2 2.0 cm and no evidence of distal metastases (Figures 1(C) and (D)).

Ultra-Low-Dose MDCT of the Chest: Influence on Automated Lung Nodule Detection

ObjectiveTo evaluate the relationship between CT dose and the performance of a computer-aided diagnosis (CAD) system, and to determine how best to minimize patient exposure to ionizing radiation while maintaining sufficient image quality for automated lung nodule detection, by the use of lung cancer screening CT.Materials and MethodsTwenty-five asymptomatic volunteers participated in the study. Each volunteer underwent a low-dose CT scan without contrast enhancement (multidetector CT with 16 detector rows, 1.25 mm section thickness, 120 kVp, beam pitch 1.35, 0.6 second rotation time, with 1.25 mm thickness reconstruction at 1.25 mm intervals) using four different amperages 32, 16, 8, and 4 mAs. All series were analyzed using a commercially available CAD system for automatic lung nodule detection and the results were reviewed by a consensus reading by two radiologists. The McNemar test and Kappa analysis were used to compare differences in terms of the abilities to detect pulmonary nodules.ResultsA total of 78 non-calcified true nodules were visualized in the 25 study subjects. The sensitivities for nodule detection were as follows: 72% at 32 mAs, 64% at 16 mAs, 59% at 8 mAs, and 40% at 4 mAs. Although the overall nodule-detecting performance was best at 32 mAs, no significant difference in nodule detectability was observed between scans at 16 mAs or 8 mAs versus 32 mAs. However, scans performed at 4 mAs were significantly inferior to those performed at 32 mAs (p < 0.001).ConclusionReducing the radiation dose (i.e. reducing the amperage) lowers lung nodule detectability by CAD. However, relatively low dose scans were found to be acceptable and to cause no significant reduction in nodule detectability versus usual low-dose CT.

Non-cardiac Findings on 64-Slice Cardiac Multi-detector CT

Background and Objectives: Multi-detector CT (MDCT) is becoming more commonly used as a diagnostic tool for various cardiac diseases, and this modality can also incidentally detect a significant number of non-cardiac findings during cardiac work-ups. The objectives of this study were to evaluate the incidence of non-cardiac findings during cardiac MDCT and to compare them with chest CT. Subjects and Methods: We enrolled 1,007 consecutive subjects (mean age: 49±10 years, males: 63%) who underwent both cardiac and chest CT (64-slice MDCT) as a part of a routine health check-up. The subjects were evaluated for the incidence of non-cardiac findings and the therapeutic consequences according to the CT protocols during the mid-term follow-up (average length of mid-term follow-up: 533±39 days). Results: Eight hundred sixty incidental non-cardiac findings were identified in 627 patients (62%) with cardiac CT. Forty-three subjects (4%) had clinically significant lesions that required additional diagnostic work-up or radiological follow-up, and these lesions were 23 cases of non-calcified nodule, 2 cases of ground glass opacity, 6 cases of pneumonia, 1 case of active tuberculosis, 2 cases of focal bronchiolitis, 3 cases of arterial lesion, 1 case of liver cirrhosis and 5 cases of extra-pulmonary masses. Five subjects (0.5%), including 2 cases (0.2%) of malignancy, had therapeutic consequences during their follow-up. Compared with chest CT, 68% (40/59) of the significant intrathoracic lesions and 67% (4/6) of the intrathoracic lesions with therapeutic consequences were documented by cardiac CT. Conclusion: In the present study, 4% of the asymptomatic patients who underwent cardiac MDCT were found to have significant non-cardiac findings that required further work-up. To avoid missing a number of clinically important findings, physicians who analyze cardiac MDCT scans should carefully evaluate not only the heart, but all the other organs that are within the scan range. (Korean Circ J 2008;38:276-283)

Lung Cancer: Interobserver Agreement on Interpretation of Pulmonary Findings at Low-Dose CT Screening

To evaluate agreement among radiologists on the interpretation of pulmonary findings at low-dose computed tomographic (CT) screening examinations for lung cancer. Institutional review board approval and informed consent were obtained. HIPAA guidelines were followed. Sixteen radiologists from the 10 National Lung Screening Trial screening centers of the National Cancer Institute's Lung Screening Study network reviewed image subsets from 135 baseline low-dose screening CT examinations in 135 trial participants (89 men, 46 women; mean age, 62.7 years +/- 5.4 [standard deviation]). Interpretations were classified into one of four of the following categories: noncalcified nodule 4 mm or larger in greatest transverse dimension (positive screening result); noncalcified nodule smaller than 4 mm in greatest transverse dimension (negative screening result); calcified, benign nodule (negative screening result); or no nodule (negative screening result). A recommendation for follow-up evaluation was obtained for each case. Interobserver agreement was evaluated by using the multirater kappa statistic and by using response frequencies and descriptive statistics. Multirater kappa values ranged from 0.58 (for agreement among all four classifications; 95% confidence interval: 0.55, 0.61) to 0.64 (for agreement on classification as a positive or negative screening result; 95% confidence interval: 0.62, 0.65). The average percentage of reader pairs in agreement on the screening result per case (percentage agreement) was 82%. There was wide variation in the total number of abnormalities detected and classified as pulmonary nodules, with differences of up to more than twofold among radiologists. For cases classified as positive, multirater kappa for follow-up recommendations was 0.35. Interobserver agreement was moderate to substantial; potential for considerable improvement exists. Clinical trial registration no. NCT00047385.

Limited value of shape, margin and CT density in the discrimination between benign and malignant screen detected solid pulmonary nodules of the NELSON trial

Purpose To evaluate prospectively the value of size, shape, margin and density in discriminating between benign and malignant CT screen detected solid non-calcified pulmonary nodules. Material and methods This study was institutional review board approved. For this study 405 participants of the NELSON lung cancer screening trial with 469 indeterminate or potentially malignant solid pulmonary nodules (>50 mm 3) were selected. The nodules were classified based on size, shape (round, polygonal, irregular) and margin (smooth, lobulated, spiculated). Mean nodule density and nodule volume were automatically generated by software. Analyses were performed by univariate and multivariate logistic regression. Results were presented as likelihood ratios (LR) with 95% confidence intervals (CI). Receiver operating characteristic analysis was performed for mean density as predictor for lung cancer. Results Of the 469 nodules, 387 (83%) were between 50 and 500 mm 3, 82 (17%) >500 mm 3, 59 (13%) malignant, 410 (87%) benign. The median size of the nodules was 103 mm 3 (range 50–5486 mm 3). In multivariate analysis lobulated nodules had LR of 11 compared to smooth; spiculated nodules a LR of 7 compared to smooth; irregular nodules a LR of 6 compared to round and polygonal; volume a LR of 3. The mean nodule CT density did not predict the presence of lung cancer (AUC 0.37, 95% CI 0.32–0.43). Conclusion In solid non-calcified nodules larger than 50 mm 3, size and to a lesser extent a lobulated or spiculated margin and irregular shape increased the likelihood that a nodule was malignant. Nodule density had no discriminative power.