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Purpose: To use individual-level data provided from the single-arm study of helical computed tomographic (CT) screening at the Mayo Clinic (Rochester, Minn) to estimate the long-term effectiveness of screening in Mayo study participants and to compare estimates from an existing lung cancer simulation model with estimates from a different modeling approach that used the same data., Materials and Methods: The study was approved by institutional review boards and was HIPAA compliant. Deidentified individual-level data from participants (1520 current or former smokers aged 50-85 years) in the Mayo Clinic helical CT screening study were used to populate the Lung Cancer Policy Model, a comprehensive microsimulation model of lung cancer development, screening findings, treatment results, and long-term outcomes. The model predicted diagnosed cases of lung cancer and deaths per simulated study arm (five annual screening examinations vs no screening). Main outcome measures were predicted changes in lung cancer-specific and all-cause mortality as functions of follow-up time after simulated enrollment and randomization., Results: At 6-year follow-up, the screening arm had an estimated 37% relative increase in lung cancer detection, compared with the control arm. At 15-year follow-up, five annual screening examinations yielded a 9% relative increase in lung cancer detection. The relative reduction in cumulative lung cancer-specific mortality from five annual screening examinations was 28% at 6-year follow-up (15% at 15 years). The relative reduction in cumulative all-cause mortality from five annual screening examinations was 4% at 6-year follow-up (2% at 15 years)., Conclusion: Screening may reduce lung cancer-specific mortality but may offer a smaller reduction in overall mortality because of increased competing mortality risks associated with smoking., ((c) RSNA, 2008.)

Purpose: To retrospectively evaluate the computed tomography (CT)-determined size, morphology, location, morphologic change, and growth rate of incidence and prevalence lung cancers detected in high-risk individuals who underwent annual chest CT screening for 5 years and to evaluate the histologic features and stages of these cancers., Materials and Methods: The study was institutional review board approved and HIPAA compliant. Informed consent was waived. CT scans of 61 cancers (24 in men, 37 in women; age range, 53-79 years; mean, 65 years) were retrospectively reviewed for cancer size, morphology, and location. Forty-eight cancers were assessed for morphologic change and volume doubling time (VDT), which was calculated by using a modified Schwartz equation. Histologic sections were retrospectively reviewed., Results: Mean tumor size was 16.4 mm (range, 5.5-52.5 mm). Most common CT morphologic features were as follows: for bronchioloalveolar carcinoma (BAC) (n = 9), ground-glass attenuation (n = 6, 67%) and smooth (n = 3, 33%), irregular (n = 3, 33%), or spiculated (n = 3, 33%) margin; for non-BAC adenocarcinomas (n = 25), semisolid (n = 11, 44%) or solid (n = 12, 48%) attenuation and irregular margin (n = 14, 56%); for squamous cell carcinoma (n = 14), solid attenuation (n = 12, 86%) and irregular margin (n = 10, 71%); for small cell or mixed small and large cell neuroendocrine carcinoma (n = 7), solid attenuation (n = 6, 86%) and irregular margin (n = 5, 71%); for non-small cell carcinoma not otherwise specified (n = 5), solid attenuation (n = 4, 80%) and irregular margin (n = 3, 60%); and for large cell carcinoma (n = 1), solid attenuation and spiculated shape (n = 1, 100%). Attenuation most often (in 12 of 21 cases) increased. Margins most often (in 16 of 20 cases) became more irregular or spiculated. Mean VDT was 518 days. Thirteen of 48 cancers had a VDT longer than 400 days; 11 of these 13 cancers were in women., Conclusion: Overdiagnosis, especially in women, may be a substantial concern in lung cancer screening., ((c) RSNA, 2007.)

Purpose: To report results of a 5-year prospective low-dose helical chest computed tomographic (CT) study of a cohort at high risk for lung cancer., Materials and Methods: After informed written consent was obtained, 1520 individuals were enrolled. Protocol was approved by institutional review board and National Cancer Institute and was compliant with Health Insurance Portability and Accountability Act, or HIPAA. Participants were aged 50 years and older and had smoked for more than 20 pack-years. Participants underwent five annual (one initial and four subsequent) CT examinations. A significant downward shift was evaluated in non-small cell lung cancers detected initially from advanced stage down to stage I by using a one-sided binomial test of proportions. Poisson regression and Fisher exact tests were used for comparisons with Mayo Lung Project., Results: In 788 (52%) men and 732 (48%) women, 61% (927 of 1520) were current smokers, and 39% were former smokers. After five annual CT examinations, 3356 uncalcified lung nodules were identified in 1118 (74%) participants. Sixty-eight lung cancers were diagnosed (31 initial, 34 subsequent, three interval cancers) in 66 participants. Twenty-eight subsequent cases of non-small cell cancers were detected, of which 17 (61%; 95% confidence interval: 41%, 79%) were stage I tumors. Diameter of cancers detected subsequently was 5-50 mm (mean, 14.4 mm; median, 10.0 mm). Analysis for a more than 50% shift in proportion of stage I non-small cell cancer detection did not show statistical significance. Forty-eight participants died of various causes since enrollment. Lung cancer mortality rate for incidence portion of trial was 1.6 per 1000 person-years. There was no significant difference in lung cancer mortality rates of cancers detected in subsequent examinations between this trial and Mayo Lung Project after separation of participants into subsets (2.8 vs 2.0 per 1000 person-years, P = .43)., Conclusion: CT allows detection of early-stage lung cancers. Benign nodule detection rate is high. Results suggest no stage shift., ((c) RSNA, 2005.)

Purpose: To evaluate a large cohort of patients at high risk for lung cancer by using screening with low-dose spiral computed tomography (CT) of the chest., Materials and Methods: A prospective cohort study was performed with 1,520 individuals aged 50 years or older who had smoked 20 pack-years or more. Participants underwent three annual low-dose CT examinations of the chest and upper abdomen. Characteristics of pulmonary nodules and additional findings were tabulated and analyzed., Results: Two years after baseline CT scanning, 2,832 uncalcified pulmonary nodules were identified in 1,049 participants (69%). Forty cases of lung cancer were diagnosed: 26 at baseline (prevalence) CT examinations and 10 at subsequent annual (incidence) CT examinations. CT alone depicted 36 cases; sputum cytologic examination alone, two. There were two interval cancers. Cell types were as follows: squamous cell tumor, seven; adenocarcinoma or bronchioloalveolar carcinoma, 24; large cell tumor, two; non-small cell tumor, three; small cell tumor, four. The mean size of the non-small cell cancers detected at CT was 15.0 mm. The stages were as follows: IA, 22; IB, three; IIA, four; IIB, one; IIIA, five; IV, one; limited small cell tumor, four. Twenty-one (60%) of the 35 non-small cell cancers detected at CT were stage IA at diagnosis. Six hundred ninety-six additional findings of clinical importance were identified., Conclusion: CT can depict early-stage lung cancers. The rate of benign nodule detection is high.

Purpose: To describe the computed tomographic (CT) findings in patients with nonspecific interstitial pneumonia (NSIP) and to compare these with the CT findings of other chronic infiltrative lung diseases., Materials and Methods: Findings in 50 patients with biopsy-proved NSIP and a CT scan were reviewed by two thoracic radiologists in consensus. After the findings were described, the observers judged whether the findings were compatible with previously published descriptions of NSIP or whether the findings would support the diagnosis of a different chronic infiltrative lung disease., Results: Eleven (22%) of the 50 patients had CT findings that were compatible with previous descriptions of NSIP. Sixteen (32%) patients had CT findings that were more compatible with usual interstitial pneumonia. The other 23 (46%) patients had findings that were nondiagnostic or most compatible with the diagnosis of another chronic infiltrative lung disease., Conclusion: Contrary to previously published articles, there are a wide variety of CT findings in cases of NSIP.

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.

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.

Purpose: To estimate the incidence of occult metastases to the brain and skeleton in patients suspected of having non-small cell lung cancer (NSCLC) (stage higher than T1Nomo) with surgically resectable disease, to assess the accuracy of screening magnetic resonance (MR) imaging and radionuclide bone scanning for help in identifying occult metastases, and to determine the effectiveness of a high dose of MR contrast material., Materials and Methods: Twenty-nine patients suspected of having NSCLC localized to the lung or to the lung and regional nodes underwent preoperative MR imaging with contrast material enhancement and radionuclide bone scanning for detection of brain or skeletal metastases. Patients were followed up for 12 months to determine the incidence of clinical metastatic disease., Results: Eight (28%) patients had occult metastatic disease to the brain or skeleton. Brain metastases were identified on MR images in five of six patients. Bone metastases were identified on MR images in four of five patients and on bone scans in three of five patients. MR imaging was no more accurate than bone scanning for skeletal evaluation. A high dose of MR contrast material allowed detection of more metastases and of small lesions., Conclusion: Contrast-enhanced MR imaging of the brain is indicated for the exclusion of brain metastases in patients with clinically operable known or possible NSCLC and a large (> 3-cm) lung mass. Skeletal imaging may be indicated if an isolated brain metastasis is detected.

Purpose: To determine whether infiltrative lung, airway, or vascular disease can be differentiated as the cause of mosaic attenuation on thin-section computed tomographic (CT) scans of the lung., Materials and Methods: Thin-section CT scans were reviewed in 70 patients examined at three institutions. A mosaic attenuation pattern and pathologic or clinical proof of a specific type of disease were demonstrated. Causes of the mosaic pattern included infiltrative lung disease (n = 37), airway disease (n = 22), and vascular disease (n = 11). Thin-section CT findings were assessed independently by two observers blinded to clinical findings., Results: The type of disease was identified correctly at CT in 58 (83%) of 70 patients by observer 1 and 57 (81%) of 70 patients by observer 2. Infiltrative lung disease was diagnosed correctly by both observers in 34 (92%) of 37 cases. Observer 1 identified 21 (95%) of 22 cases of airway disease and three (27%) of 11 cases of vascular disease. Observer 2 identified 19 (86%) of 22 cases of airway disease and four (36%) of 11 cases of vascular disease., Conclusion: Infiltrative lung disease and airway disease may be differentiated reliably as the cause of mosaic attenuation on lung CT scans, whereas vascular disease is often misinterpreted as infiltrative lung disease or airway disease.

Purpose: To determine if there is a subset of patients undergoing surgical biopsy for diffuse lung disease in whom accurate diagnosis can be made with computed tomography (CT) only., Materials and Methods: Two chest radiologists retrospectively reviewed the CT scans of 85 patients in whom surgical biopsy for diffuse lung disease was performed. Thin-section CT images were available in 58 (68%) of the 85 cases. By consensus, the radiologists listed the three most likely diagnoses in order of probability and rated their level of confidence in the first choice., Results: Each of 85 patients with diffuse lung disease had one of 16 diseases. In 79 (93%) cases, the correct diagnosis was one of the three choices. In 54 (64%) cases, the correct diagnosis was the radiologists' first choice. A high level of confidence in the first choice was reached in 20 (24%) cases; all 20 cases were forms of chronic lung disease. In 18 (90%) of these 20 cases, the first choice was correct., Conclusion: In a subset of patients with diffuse lung disease who undergo surgical biopsy, accurate diagnosis can be made with CT findings only.

Purpose: To determine if lung nodule enhancement measured with computed tomography (CT) is directly related to the likelihood of malignancy and to nodule vascularity., Materials and Methods: Radiologically indeterminate 7-30-mm pulmonary nodules were studied in 107 patients with malignant neoplasms (n = 52), granulomas (n = 51), and benign neoplasms (n = 4). Attenuation was recorded from serial thin-section CT scans before and after injection of contrast material. Twenty-four histologic specimens were graded after immunoperoxidase vascular staining with antibody to factor VIII-associated antigen., Results: Malignant neoplasms were enhanced (median, 46.5 HU; range, 11-110 HU) statistically significantly more than granulomas and benign neoplasms (median, 8 HU; range, -10 to 94 HU) (P < .001). With 20 HU as the threshold for a positive test result, the sensitivity was 98%, specificity was 73%, and accuracy was 85% (prevalence of malignancy, 49% ¿52 of 107 nodules]). The degree of enhancement was statistically significantly related to the amount of central vascular staining (P < .001)., Conclusion: Enhancement appears to be an indicator of malignancy and vascularity. These prospective findings corroborate previously reported results.

Purpose: To test a neural network in differentiation of benign from malignant solitary pulmonary nodules., Materials and Methods: Neural networks were trained and tested on the characteristics of 318 nodules. Predictive accuracy of the network was judged for calibration and discrimination. Network results were compared with those with a simpler Bayesian method., Results: The Brier score was 0.142 (calibration, 0.003; discrimination, 0.139) for the neural network and 0.133 for the Bayesian analysis (calibration, 0.012; discrimination, 0.121). Analysis of the calibration curve revealed no significant difference (P < .05) between the slope (b = 1.09) and the line of identity (b = 1) for the neural network or the Bayesian analysis. The area under the receiver operating characteristic curve was 0.871 for the neural network and 0.894 for the Bayesian analysis (P < .05). There were 23 and 21 false-positive predictions and 18 and six false-negative predictions for the neural network and Bayesian analysis, respectively., Conclusion: The Bayesian method was better than the neural network in prediction of probability of malignancy in solitary pulmonary nodules.

Purpose: To determine if the degree of enhancement of pulmonary nodules is directly related to the likelihood of malignancy and to the vascularity of the nodule., Materials and Methods: Uncalcified 6-40-mm-diameter pulmonary nodules were studied in 163 patients with malignant neoplasm (n = 111), granuloma (n = 43), and benign neoplasm (n = 9). Serial thin-section computed tomography (CT) was performed before and after injection of 100 mL of nonionic contrast material at 2 mL/sec. The maximum level of enhancement was recorded. Eighteen histologic specimens were graded after vascular staining., Results: Malignant neoplasms enhanced (median, 40.0 HU; range, 20-108 HU) significantly more than granulomas and benign neoplasms (median, 12.0 HU; range, -4 to 58 HU) (P < .001). With 20 HU as the threshold for a positive test, sensitivity was 100%; specificity, 76.9%; positive predictive value, 90.2%; negative predictive value, 100%; and accuracy, 92.6% (prevalence of malignancy, 68.1%). Degree of enhancement was significantly related to amount of central vascular staining (P = .003)., Conclusion: Enhancement is an indicator of malignancy and vascularity.

Purpose: To evaluate the indications for and complications, accuracy, and techniques of percutaneous adrenal biopsy performed from 1982 through 1991 at the authors' institution., Materials and Methods: Two hundred seventy-seven percutaneous adrenal biopsies were performed in 270 patients (175 male and 102 female patients, aged 31-84 years). Imaging studies and histories were reviewed, and each patient's case was followed up for at least 1 year after the biopsy. A patient was excluded from the study only if follow-up data could not be obtained., Results: The accuracy of percutaneous adrenal biopsy was 90% (249 of 277 biopsies). In the first 5 years of the study, the accuracy was 85% (87 of 102 biopsies); in the latter 5 years it was 93% (163 of 175 biopsies). The sensitivity was 81%, and the specificity was 99%. The positive predictive value was 99%, and the negative predictive value was 80%. The complication rate was 2.8%., Conclusion: Percutaneous biopsy is a safe, accurate procedure for the diagnosis of pathologic conditions of the adrenal glands. The most common indication for a biopsy is the presence of an adrenal mass in a patient with lung cancer.

The authors compared asymmetric and conventional screen-film systems for chest radiography. The new imaging system, with asymmetric construction of the screens and film, has image quality characteristics substantially different from those of available screen-film combinations. This asymmetric screen-film system consists of a thin (high-resolution) front screen and a high-contrast emulsion, a thick (lower-resolution) back screen and a low-contrast emulsion, and technology that reduces the crossover exposure and prevents light from the front screen from exposing the back emulsion and vice versa. With this system, density, contrast, and resolution can be increased in selected regions while maintaining density and contrast in the rest of the image. Also, the resolution of this system varies as a function of density. Preliminary image quality and sensitometric studies indicate the new system is superior for chest radiography because it provides better visualization of mediastinal, retrocardiac, and diaphragmatic regions while yielding better contrast and resolution in lung parenchyma.

To evaluate the findings on thin-section computed tomographic (CT) scans in desquamative interstitial pneumonia (DIP), the CT scans from 22 patients aged 22-71 years (mean age, 43 years) were reviewed. In all patients, DIP was proved with open-lung biopsy performed 1 day to 17 months before or after examination with CT (median interval, 1.5 months). The lungs were divided into three zones (upper, middle, and lower); each zone was evaluated separately. The predominant finding was the presence of areas of ground-glass attenuation that involved the middle and lower lung zones in all patients and the upper lung zones in 18 patients (82%). Such areas had a lower lung zone predominance in 16 patients (73%) and a predominantly peripheral distribution in 13 patients (59%). Irregular lines of attenuation suggestive of fibrosis were seen in 11 patients (50%) and cystic changes, in seven patients (32%). The distribution of abnormalities in DIP is similar to that seen in usual interstitial pneumonia (UIP), but the greater extent of ground-glass attenuation and the paucity of cystic changes in DIP should enable distinction from UIP in most patients.

Pulmonary Mycobacterium avium-intracellulare (MAI) complex has been reported with increasing frequency, but computed tomographic (CT) evaluation of pulmonary MAI complex has been seldom reported. The authors retrospectively reviewed chest CT examinations performed in 62 patients with positive MAI cultures within 1 month of CT. Of the 62 patients, 40 had bronchiectasis and 60 had infiltrates, usually of the nodular variety (39 patients). All 35 patients with small nodular infiltrates had bronchiectasis. These 35 patients did not have concurrent malignancy or clinical evidence of immunocompromise, and 29 (83%) of them were women (mean age, 66 years). Of the 27 patients without small nodular infiltrates and bronchiectasis, 25 had underlying malignancy or immunocompromise. The predominance of older women without underlying malignancy or immunocompromise but with findings of small nodular infiltrates and bronchiectasis at chest CT may indicate such patients to be a subtype of patients with pulmonary MAI complex.

The authors hypothesized that the degree of contrast material enhancement of a pulmonary nodule, measured with computed tomography (CT), may indicate the likelihood of malignancy. Fifty-two patients with uncalcified solitary pulmonary nodules (diameter, 6-30 mm) were studied. Five single serial thin-section CT scans were obtained at 1-minute intervals after injection of 100 mL of nonionic contrast material. Twenty-two patients were excluded because the diagnosis was not clearly established: The observation period was less than 2 years, or the examination was technically inadequate. Malignant nodules were identified in 23 of the 30 remaining patients, and benign nodules were identified in seven. Within the first 2 minutes after the injection, all the malignant nodules had enhanced by 20 HU or greater (only one benign nodule had that degree of enhancement). The authors conclude that the degree of contrast material enhancement of pulmonary nodules as measured with CT may indicate the likelihood of malignancy.