PURPOSE: To study the impact of inversion of soft-copy chest radiographs on the detection of small solitary pulmonary nodules using a high-resolution monitor. MATERIALS AND METHODS: The study group consisted of 80 patients who had undergone posterior chest radiography; 40 had a solitary noncalcified pulmonary nodule approximately 1 cm in diameter, and 40 were control subjects. Standard and inverse digital images using the inversion tool on a PACS system were displayed on high-resolution monitors (2048x2560x8 bit). Ten radiologists were requested to rank each image using a five-point scale (1=definitely negative, 3=equivocal or indeterminate, 5=definite nodule), and the data were interpreted using receiver operating characteristic (ROC) analysis. RESULTS: The area under the ROC curve for pooled data of standard image sets was significantly larger than that of inverse image sets (0.8893 and 0.8095, respectively; p<0.05). Interpretation of both standard and inversion images did not lead to more accurate detection of small pulmonary nodules (area under the ROC curve: 0.8835 and 0.8893, respectively; p>0.05). CONCLUSION: For detecting small solitary pulmonary nodules, inverse digital images were significantly inferior to standard digital images.
Diagnosis* ; Humans ; Radiographic Image Enhancement ; Radiography ; Radiography, Thoracic ; ROC Curve* ; Solitary Pulmonary Nodule* ; Thorax

PURPOSE: To determine whether the maximal enhancement time in dynamic CT is different between benign and malignant solitary pulmonary nodules (SPN)s, and to evaluate the value of densitometry on dynamic CT in predicting the malignancy of SPN. MATERIALS AND METHODS: Fifty-six patients with SPN of less than 4cm in diameter as seen on chest radiograph and SPN without benign pattern of calcification or fat, as seen on pre-enhancement spiral CT scans were included in this study. SPN with small cavitation sufficient to measure CT density, were also included.Thirty-four SPNs were diagnosed pathologically or radiologically as 20 malignant nodules and 14 benign nodules.Dynamic CT was performed by two techniques after injection of 50ml of nonionic contrast media at the rate of 2ml/sec. In 28 patients, incremental dynamic CT was performed before and of 15 seconds, 1 minute, 2 minutes, 3 minutes, and 4 minutes after injection of contrast media during shallow respiration. In 28 patients, double spiral CT was performed 2 minutes and 3 minutes after injection of contrast media during single breath hold. CT readings were taken at the central portion of SPNs, with a circular region of interest. The degree and time of maximal enhancement were recorded. RESULTS: In dynamic CT the maximal enhancement time of SPNs was not significantly different between malignant (2.73+/-1.27 minute) and benign nodules (2.56+/-1.24 minute). The enhancement of malignant nodules was significantly greater (21.42+/-12.17 HU) than of benign nodules (5.15+/-5.25 HU) (p<.0001). CONCLUSION: In dynamic CT of SPNs, there is no difference in maximal enhancement time between benign and malignant nodules ; enhancement of the latter is significantly greater than that of the former. Maximal enhancement greater than 15 HU can be a good predictor of malignancy of SPNs.
Contrast Media ; Densitometry ; Humans ; Radiography, Thoracic ; Reading ; Respiration ; Solitary Pulmonary Nodule* ; Tomography, Spiral Computed

PURPOSE: The aim of this study was to compare the accuracy of the conventional method and Bayesian analysisin estimating the probability of malignancy in solitary pulmonary nodules. MATERIALS AND METHODS: The studyinvolved 83 pathologically proven cases of solitary pulmon ary nodules, 44 of which were malignant, and 39,benign. To estimate the probability of malignancy in solitary pulmonary nodules, chest radiographs and CT scans ofthe 83 patients were interpreted by a team of six ; three of the six used the conventional method of subjectiveinterpretation and the others. Bayesian analysis. The smoking history of 59 of the patients was obtained, and itwas decided whether this would help determine the probability of malignancy. RESULTS: On average, those using theconventional method correctly interpreted 34.7(78.9%) of 44 cases of malignant nodules and 27.7(71%) of 39 benignnodules, while those using Bayesian analysis correctly classified 32.3 cases of malignant nodules(73.4%) and 25.3cases of benign nodules(64.9%). Between the two teams, there was no statistically significant difference in theaccuracy of qualitative assessment(P>.05). In ROC analysis conventional interpretation and Bayesian analysisshowed an accuracy of Az=80.8 and Az=76.7, respectively. Among 59 patients known to have smoked, the conventionalmethod showed an accuracy of Az=79.0 without this knowledge and Az=80.2 with the knowledge for Bayesian analysis,the corresponding figures were Az=77.2 and Az=72.5, respectively. Information relating to smoking history thus didnot significantly improve the accuracy of prediction(p>.05). CONCLUSION: For estimating the probability ofmalignancy in solitary pulmonary nodules, the accuacy of the conventional method of interpretation is notsignificantly different from that of Bayesian analysis; information relating to smoking history significantlyimprove the accuracy of neither method.
Bayes Theorem* ; Humans ; Radiography, Thoracic ; ROC Curve ; Smoke ; Smoking ; Solitary Pulmonary Nodule* ; Tomography, X-Ray Computed

PURPOSE: The purpose of this study was to compare the diagnostic accuracies of chest radiographs and chest CTin the diagnosis of a solitary pulmonary nodule(SPN), and to determine the role of CT and CT findings which aid inthe differential diagnosis of nodules. MATERIALS AND METHODS: A retrospective study was done on 54 patients inwhom SPN was found on chest radiographs and chest CT was carried out. The study involved 25 benign and 29 malignant nodules, confirmed histopathologically and clinically. Chest radiographs and CT scans were reviewed separately in randomized order by two chest radiologists who for each film listed the three most likely diagnose sin descending order. The radiologists recorded the confidence value of the most probable diagnosis, and also the marginal and internal characteristics of nodules and their size, as nodules seen on chest CT scans. RESULTS: Diagnostic rates in the differential diagnosis of benign and malignant nodules were 65.7% by radiography and 77.8% by CT. Correct first-choice diagnosis was by radiography in 30.6 % of cases, and by CT in 41.7%. Using radiographs, and the correct diagnosis was among the top-three choices in 61.1% of cases ; with CT, the corresponding figure was 76.8%. Overall, a confident diagnosis was reached more often with the CT(41.7%) than with the chest radiograph(21.4%) ; diagnaotic accuracy was 60.0% and 52.2%, respectively. CT findings which imply abenign nodule include smooth margins and diffuse internal calcifications, whereas marginal lobulations, air-bronchograms, internal low density without cavitation, eccentric calcifications, and large size suggest malignancy. We faund that CT findings such as well-defined margins, spiculations, pleural tail or internal homogeneity did not contribute in the differentiation between benign and malignant nodules. CONCLUSION: CT issuperior to chest radiography in the differential diagnosis of the solitary pulmonary nodule. Using CT, diagnosis was accurate and made with a high level of confidence, especially with the application of CT findings which aid inthe differential diagnosis of nodules.
Diagnosis ; Diagnosis, Differential* ; Humans ; Radiography* ; Radiography, Thoracic ; Retrospective Studies ; Solitary Pulmonary Nodule* ; Thorax* ; Tomography, X-Ray Computed

OBJECTIVE: To evaluate the influence of high-pitch mode (HPM) in dual-source computed tomography (DSCT) on the accuracy of three-dimensional (3D) volumetry for solid pulmonary nodules. MATERIALS AND METHODS: A lung phantom implanted with 45 solid pulmonary nodules (n = 15 for each of 4-mm, 6-mm, and 8-mm in diameter) was scanned twice, first in conventional pitch mode (CPM) and then in HPM using DSCT. The relative percentage volume errors (RPEs) of 3D volumetry were compared between the HPM and CPM. In addition, the intermode volume variability (IVV) of 3D volumetry was calculated. RESULTS: In the measurement of the 6-mm and 8-mm nodules, there was no significant difference in RPE (p > 0.05, respectively) between the CPM and HPM (IVVs of 1.2 +/- 0.9%, and 1.7 +/- 1.5%, respectively). In the measurement of the 4-mm nodules, the mean RPE in the HPM (35.1 +/- 7.4%) was significantly greater (p < 0.01) than that in the CPM (18.4 +/- 5.3%), with an IVV of 13.1 +/- 6.6%. However, the IVVs were in an acceptable range (< 25%), regardless of nodule size. CONCLUSION: The accuracy of 3D volumetry with HPM for solid pulmonary nodule is comparable to that with CPM. However, the use of HPM may adversely affect the accuracy of 3D volumetry for smaller (< 5 mm in diameter) nodule.
Humans ; Imaging, Three-Dimensional/instrumentation/*methods ; Lung/radiography ; Lung Neoplasms/*radiography ; Multiple Pulmonary Nodules/*radiography ; Phantoms, Imaging ; Solitary Pulmonary Nodule/*radiography ; Tomography, X-Ray Computed/instrumentation/*methods

PURPOSE: Differential diagnosis of solitary pulmonary nodule with cavity includes lung abscess, tuberculoma, bronchogenic carcinoma, metastasis and trauma, etc. We analyzed the CT appearance of tubercuioma presenting as a solitary pulmonary nodule with cavity and describe the findings which suggest tuberculoma in the differential dignosis of soliary pulmonary nodule with cavity. MATERIALS AND METHODS: 25 patients with solitary pulmonary nodule(diameter less than 4 cm) without surrounding parenchymal consolidation on chest radiograph, who had a cavity within the nodule on CT, were included in our study. Density of the nodule, maximal wall thickness, the character of inner and outer wall margin, location of cavity within the nodule, location of the nodule, presence or absence of satellite lesions and calcification were analyzed. RESULTS: Solitary tuberculoma with cavity showed maximal wall thickness more than 15 mm in 40%(10/25) and 5-14 mm in 56%(14/25), eccentric cavitation in 84%(21/25) and concentric cavitation in 16%(4/25), spiculated outer wall margin in 56%(14/15) and Iobulated margin in 32%(8/25), smooth inner wall margin in 60%(15/25) and nodular margin in 40%(10/25). CT density of the cavity wall compared with the chest wall muscle was low in 84%(21/25) and isodense in 16%(4/25). Accompanying satellite lesions were seen in 84% (21/25) and calcification was visible in 28%(7/25). CONCLUSION: The CT findings of solitary tuberculoma with cavity are relative peripheral location, eccentric cavitation, finely spiculated outer wall margin, and mean maximal wall thickness of 13.2 mm, which are also the common features of malignant nodule. However, relative low density of the nodule compared to the chest wall muscle and surrounding satellite lesions can be additional clues favoring solitary tuberculoma with cavity on CT.
Carcinoma, Bronchogenic ; Diagnosis, Differential ; Humans ; Lung Abscess ; Neoplasm Metastasis ; Radiography, Thoracic ; Solitary Pulmonary Nodule ; Thoracic Wall ; Tuberculoma*

OBJECTIVE: This study was designed to evaluate follow-up results in terms of patient prognosis for malignant pulmonary nodules depicted as pure ground-glass opacity (GGO) lesion observed at high-resolution CT (HRCT). MATERIALS AND METHODS: Surgical removal for malignant GGO nodules was accomplished in 58 patients (26 men, 32 women; mean age, 57 years; age range, 29-78 years). Patient prognoses were assessed by patient clinical status and the presence of changes in nodule size determined after a follow-up HRCT examination. Differences in patient prognoses were compared for nodule number, size, surgical method, change in size before surgical removal, and histopathological diagnosis by use of Fisher's exact test and Pearson's chi-squared test. RESULTS: Of the 58 patients, 40 patients (69%) were confirmed to have a bronchioloalveolar carcinoma (BAC) and 18 patients (31%) were confirmed to have an adenocarcinoma with a predominant BAC component. Irrespective of nodule size, number, treatment method, change in size before surgical removal and histopathological diagnosis, neither local recurrence nor a metastasis occurred in any of these patients as determined at a follow-up period of 24 months (range; 12-65 months). Of 14 patients with multiple GGO nodules, all of the nodules were resected without recurrence in six patients. In the remaining eight patients, the remaining nodules showed no change in size in seven cases and a decrease in size in one case as determined after a follow-up CT examination. CONCLUSION: Prognoses in patients with pure GGO malignant pulmonary nodules are excellent, and not significantly different in terms of nodule number, size, surgical method, presence of size change before surgical removal and histopathological diagnosis.
Adenocarcinoma/pathology/radiography/surgery ; Adenocarcinoma, Bronchiolo-Alveolar/pathology/radiography/surgery ; Adult ; Female ; Humans ; Lung Neoplasms/pathology/*radiography/surgery ; Male ; Middle Aged ; Multiple Pulmonary Nodules/pathology/*radiography/surgery ; Prognosis ; Solitary Pulmonary Nodule/pathology/*radiography/surgery ; *Tomography, X-Ray Computed ; Young Adult

OBJECTIVE: We wanted to evaluate the usefulness of the computer-aided detection (CAD) system for detecting pulmonary nodules in real clinical practice by using the CT images. MATERIALS AND METHODS: Our Institutional Review Board approved our retrospective study with a waiver of informed consent. This study included 166 CT examinations that were performed for the evaluation of pulmonary metastasis in 166 patients with colorectal cancer. All the CT examinations were interpreted by radiologists and they were also evaluated by the CAD system. All the nodules detected by the CAD system were evaluated with regard to whether or not they were true nodules, and they were classified into micronodules (MN, diameter < 4 mm) and significant nodules (SN, 4 < or = diameter < or = 10 mm). The radiologic reports and CAD results were compared. RESULTS: The CAD system helped detect 426 nodules; 115 (27%) of the 426 nodules were classified as true nodules and 35 (30%) of the 115 nodules were SNs, and 83 (72%) of the 115 were not mentioned in the radiologists' reports and three (4%) of the 83 nodules were non-calcified SNs. One of three non-calcified SNs was confirmed as a metastatic nodule. According to the radiologists' reports, 60 true nodules were detected, and 28 of the 60 were not detected by the CAD system. CONCLUSION: Although the CAD system missed many SNs that are detected by radiologists, it helps detect additional nodules that are missed by the radiologists in real clinical practice. Therefore, the CAD system can be useful to support a radiologist's detection performance.
Colorectal Neoplasms/*pathology ; *Diagnosis, Computer-Assisted ; Female ; Humans ; Lung Neoplasms/*radiography/secondary ; Male ; Middle Aged ; Retrospective Studies ; Solitary Pulmonary Nodule/*radiography/secondary ; *Tomography, X-Ray Computed

OBJECTIVE: To determine the optimum low dose (LD) digital tomosynthesis (DT) setting, and to compared the image quality of the LD DT with that of the standard default (SD) DT. MATERIALS AND METHODS: Nine DT settings, by changing tube voltage, copper filter, and dose ratio, were performed for determining the LD setting. Among combinations of DT setting, a condition providing the lowest radiation dose was determined. Eighty artificial nodules less than 1 cm in diameter (subcentimeter nodules: 40, micronodules less than 4 mm: 40) were attached to a Styrofoam and a diaphragm of the phantom. Among these, 38 nodules were located at the periphery of the lung (thin area) and 42 nodules were located at the paravertebral or sub-diaphragmatic area (thick area). Four observers counted the number of nodules detected in the thick and thin areas. The detection sensitivity in SD and LD settings were calculated separately. Data were analyzed statistically. RESULTS: The lowest LD setting was a combination of 100 kVp, 0.3 mm additional copper filter, and a 1 : 5 dose ratio. The effective dose for the LD and SD settings were 62 microSv and 140 microSv, separately. A 56.7% dose reduction was achieved in the LD setting compared with the SD setting. Detection sensitivities were not different between the SD and the LD settings except between observers 1 and 2 for the detection of micronodules in the thick area. CONCLUSION: LD DT can be effective in nodule detection bigger than 4 mm without a significant decrease in image quality compared with SD DT.
Diagnosis, Computer-Assisted/*methods ; Humans ; Lung Neoplasms/radiography ; *Phantoms, Imaging ; *Radiation Dosage ; Radiographic Image Enhancement/*methods ; Sensitivity and Specificity ; Solitary Pulmonary Nodule/radiography

OBJECTIVETo assess inter-observer variations of pulmonary nodule marking in routine clinical chest digital radiograph (DR) softcopy reading by using a lung nodule computer toolkit.

METHODSA total of 601 chest posterior-anterior DR images were randomly selected from routine outpatient screening in Peking Union Medical College Hospital. Two chest radiologists with experience more than ten years were first asked to read the images and mark all suspicious nodules independently by using computer toolkit IQQA-Chest, and to indicate the likelihood for each nodule detected. They were also asked to draw the boundary of the identified nodule manually on an enlarged region of interest, which was instantly analyzed by IQQA-Chest. Two sets of diagnostic reports, including the marked nodules, likelihood, manually drawn boundaries, quantitative measurements, and radiologists' names, were automatically generated and stored by the computer system. One week later, the two radiologists read the same images together by using the same computer toolkit without referring to their previous reading results. Marking procedure was the same except that consensus was reached for each suspicious region. Statistical analysis tools provided in the IQQA-Chest were used to compare all the three sets of reading results.

RESULTSIn the independent readings, Reader 1 detected 409 nodules with a mean diameter of 12.4 mm in 241 patients, and Reader 2 detected 401 nodules with a mean diameter of 12.6 mm in 253 patients. In the consensus reading, a total of 352 nodules with a mean diameter of 12.4 mm were detected in 220 patients. Totally, 42.3% of Reader 1's and 45.1% of Reader 2's marks were confirmed by the consensus reading. About 40% of each reader's marks agreed with the other. There were only 130 (14.4%) out of the total 904 unique nodules were confirmed by both readers and the consensus reading. Moreover, 5.6% (51/904) of the marked regions were rated identical likelihood in all three readings. Statistical analysis showed significant differences between Readers 1 and 2, and between consensus and Reader 2 in determining the likelihood of the marks (P < 0.01), but not between consensus and Reader 1. No significant difference in terms of size was observed in nodule segmentation between either two of the three readings.

CONCLUSIONLarge variations in nodule marking and nodule-likelihood determination but not in nodule size were observed between experts as well as between single-person reading and consensus reading.

Adult ; Aged ; Computers ; Female ; Humans ; Lung Neoplasms ; diagnostic imaging ; Male ; Middle Aged ; Multiple Pulmonary Nodules ; diagnostic imaging ; Observer Variation ; Radiography ; Solitary Pulmonary Nodule ; diagnostic imaging