CONCLUSION. Fast and more accurate TB testing such as bacterial DNA fingerprinting and whole-blood interferon- assay has been developed. Miliary or disseminated primary pattern or atypical manifestations of pulmonary TB are common in patients with impaired immunity. CT plays an important role in the detection of TB in patients in whom the chest radiograph is normal or inconclusive, in the determination of disease activity, in the detection of complication, and in the management of TB by providing a roadmap for surgical treatment planning. PET scans using ¹⁸F-FDG or ¹¹C-choline can sometimes help differentiate tuberculous granuloma from lung malignancy.

SUBJECTS AND METHODS. Breath sounds (frequency range, 150–250 Hz) recorded from the backs of 151 healthy asymptomatic subjects (96 nonsmokers and 55 smokers) by the VRIxp device were mapped to create a sequence of 2D images. Three raters interpreted and scored the images for predefined static and dynamic features. In addition, quantitative lung data were analyzed for characteristic regional distributions.

RESULTS. The readers of the images had good inter- and intrarater agreement. Image development in 93% of the evaluations showed an inspiratory and expiratory phase with a progressive and regressive stage that developed bilaterally in a vertical and synchronized manner. Characteristic image features of the maximum energy frame included a smooth, rounded, uninterrupted contour and a planar distribution, area size, and intensity that had right–left symmetry. Quantitative lung data expressed as percentages of the total (100%) vibration energy were normally distributed with mean values (± SD) of 55% ± 6% for the left lung and 45% ± 6% for the right lung. Most of the subjects with images, quantitative lung data, or both lacking these typical features were cigarette smokers or had a history of smoking (p < 0.05).

CONCLUSION. Breath sounds in healthy asymptomatic subjects can be recorded and displayed in a dynamic series of images that have predictable and characteristic features recognizable and complemented by quantitative lung data. Identification and description of these characteristic image features in this study will facilitate future studies of vibration imaging in specific pulmonary diseases.

SUBJECTS AND METHODS. In a prospective study, seven patients underwent MDCT according to a low-dose protocol (40 mAs, 120 kVp) before and after stent placement. The positions of the stents in the segmental bronchi were analyzed and compared with the bronchoscopic findings, which were reference standard. Patency versus lack of patency of stents was classified with five levels of confidence, and a definitive diagnosis was assigned to each stent. Prediction of stent dislodgment, follow-up findings, and complications occurring during the observation period were recorded. Consensus reading was performed by two radiologists. Statistical analysis was conducted by receiver operating characteristic analysis or four-field table.

RESULTS. Seven patients underwent implantation of 37 stents (mean, 5 ± 2 [SD] stents per patient; range, 2–8 stents). The area under the curve for differentiating patent from occluded stents was 0.995 with resulting sensitivity and specificity of 86.5% and 98.1%. The correct diagnosis of patency was established with MDCT for all but one stent (sensitivity, 94.7%; specificity, 100%). Sensitivity and specificity for prediction of dislodgment were 80% and 91%. Five stents were not identified during inspection bronchoscopy but were found in a regular position at MDCT. Three instances of minor bleeding and one of pneumothorax resolved spontaneously. The mean effective dose of the scan was 1.3 ± 0.6 mSv.

CONCLUSION. Low-dose MDCT is feasible for radiologic monitoring after airway bypass procedure.

MATERIALS AND METHODS. This study included 54 pulmonary nodules (≥ 5 mm in diameter) in 51 consecutive patients (37 men, 14 women; mean age, 65.7 years; age range, 31–88 years). Thirty-six (67%) of the 54 pulmonary nodules were malignant, and 18 (33%) were benign. Two radiologists independently reviewed the signal intensity of the nodules on DWI with a b factor of 1,000 s/mm² using a 5-point rank scale without knowledge of clinical data. This scale was based on the following scores: 1, nearly no signal intensity; 2, signal intensity between 1 and 3; 3, signal intensity almost equal to that of the thoracic spinal cord; 4, higher signal intensity than that of the spinal cord; and 5, much higher signal intensity than that of the spinal cord. The Mann-Whitney U test and the receiver operating characteristic (ROC) curve were used to calculate the difference between the scores of malignant and benign nodules.

RESULTS. On DWI, the mean score of malignant pulmonary nodules (4.03 ± 1.16 [SD]) was significantly higher (p < 0.01) than that of benign nodules (2.50 ± 1.47), with an area under the ROC curve of 0.796 (95% CI, 0.665–0.927). When a score of 3 was considered as a threshold, the sensitivity, specificity, and accuracy were 88.9% (95% CI, 78.6–99.2%), 61.1% (38.6–83.6%), and 79.6% (68.9–90.3%), respectively. Three small metastatic nodules (13, 16, and 20 mm) and one bronchioloalveolar carcinoma scored 1 or 2 on the 5-point rank scale. Three granulomas, two active inflammatory lung nodules, and one fibrous nodule scored 4 or 5.

CONCLUSION. The signal intensity of pulmonary nodules may be useful for malignant and benign differentiation on DWI. However, the interpretation of small metastatic nodules, nonsolid adenocarcinoma, some granulomas, and active inflammatory nodules should be approached with caution.

MATERIALS AND METHODS. We reviewed a total of 575 CT angiograms obtained to evaluate for PE at a large level 1 trauma teaching hospital from January 2004 through March 2005. Various clinical settings were used for 267 inpatient (46%), 258 emergency department (45%), and 50 outpatient (9%) studies. We excluded CTA performed for other reasons, repeated CTA, and patient records with incomplete clinical data. On the basis of chart review in which the investigators were blinded to final diagnoses, pretest probability of PE according to the Wells criteria was retrospectively assigned to each patient. D-dimer values, when obtained, also were reviewed. The diagnosis of PE was based on final CTA reports.

RESULTS. PE was diagnosed in 9.57% of 575 patients. Positivity rates by location were 32 (12%) of the 267 inpatients, 22 (8.5%) of the 258 emergency department patients, and one (2.0%) of the 50 outpatients. Three (< 1%) of the 575 patients had high probability of PE, even though 351 patients had gone directly to CTA. Of the other 572 patients, 158 (28%) had intermediate and 414 (72%) low probability of PE. In the high, intermediate, and low probability groups, two (67%), 24 (15%), and 29 (7%), respectively, of the patients had PE. A D-dimer assay was performed for 224 (39%) of the 575 patients. Thirty-nine (17%) of the 224 patients had normal results (< 0.5 µg/mL); 107 (48%), intermediate results (0.6–2.0 µg/mL); and 78 (35%), abnormal results (> 2.0 µg/mL). In the emergency department cohort, 151 (59%) of 258 patients underwent a D-dimer assay. Thirty-two (21%) of the 151 patients had normal results; 81 (54%), intermediate results; and 38 (25%), abnormal results. Only one patient with a normal D-dimer level and three patients with intermediate D-dimer levels had PE, the equivalent of 3% of each group. The number of CTA examinations ordered for patients with normal and intermediate D-dimer results was 146 (25% of the 575 total studies). Twenty-two (8%) of the 258 emergency department patients had PE, and clinical suspicion of PE was high for 11 (50%), intermediate for 10 (45%), and low for one (5%) of those patients.

CONCLUSION. Our data showed suboptimal use of the Wells criteria and subjective overestimation of the probability of PE before ordering of CTA. Although a definitive acceptable PE positivity rate for CTA has not been established, the 10% yield represents overuse of CTA as a screening rather than a diagnostic examination.

MATERIALS AND METHODS. Dual-phase FDG PET studies were conducted with imaging 1 and 2 hours after FDG injection, and pulmonary lesions with an initial mean SUV less than 2.5 were identified. Nodules with pathologic reports were included in the study. The differences in mean SUV, maximal SUV, and retention index between benign and malignant pulmonary lesions were analyzed. Receiver operating characteristic analysis was performed to evaluate the discriminating validity of the retention index.

RESULTS. A total of 31 lesions (15 benign, 16 malignant) were included in the study. Among the benign lesions, 12 were granulomatous inflammation, including 10 tuberculosis lesions and two cryptococcosis lesions, and three were focal fibrosis. A retention index greater than 0% was observed in 87% of the benign lesions; 60% of the benign lesions had a retention index greater than 10%. Among the malignant lesions, 75% had a retention index greater than 0%, and 62% had a retention index greater than 10%. We found no significant differences in mean SUV, maximal SUV, and retention index between benign and malignant lesions. The area under the receiver operating characteristic curve did not differ from 0.5.

CONCLUSION. Delayed FDG PET is not useful for differentiating benign and malignant pulmonary nodules with an initial mean SUV less than 2.5 in geographic regions with epidemic granulomatous disease such as tuberculosis or in patients at high risk of granulomatous inflammation.

MATERIALS AND METHODS. Twenty images were compressed reversibly and irreversibly to 6:1–30:1. To analyze the two regions separately (lungs; and chest wall and mediastinum), the compressed pixels outside each tested region were replaced with the original pixels. By comparing the compressed and original images, three radiologists independently rated the compression artifacts as grade 0, none, indistinguishable; 1, barely perceptible; 2, subtle; or 3, significant. At each compression level, the two regions were compared for the readers' responses, peak signal-to-noise ratio (PSNR), and HDR-VDP results. Wilcoxon's signed rank tests and exact tests for paired proportions were used with a p value threshold of 0.05.

RESULTS. Artifacts were rated as lower grades in the lungs than in the chest wall and mediastinum, showing statistical significances at 10:1–20:1 for reader 1, 8:1–15:1 for reader 2, and 8:1–20:1 for reader 3. Grade 0 was more frequent in the lungs, showing statistical significances at 10:1 for reader 1 and at 8:1–10:1 for readers 2 and 3. The results of PSNR indicated greater artifacts in the lungs (p < 0.001), whereas HDR-VDP results indicated fewer artifacts in the lungs (p < 0.001).

CONCLUSION. Although compression artifacts are mathematically greater in the lungs than in the chest wall and mediastinum, radiologists' artifact perceptions are the opposite, which can be successfully reproduced by HDR-VDP.

MATERIALS AND METHODS. Thirty-five thin-section (1 mm) and 35 corresponding thick-section (5 mm) images were compressed to reversible and irreversible 4:1, 6:1, 8:1, 10:1, and 15:1. In each compressed image, pixels outside the lung were replaced with those from the original image. By comparing the compressed and original images, three radiologists independently rated the compression artifacts using grades of 0 (none, the two images were indistinguishable), 1 (image differences were barely perceptible), 2 (image differences were subtle), or 3 (image differences were significant). At each compression level, thin and thick sections were compared for peak signal-to-noise ratio (PSNR) using paired t tests and for the readers' responses using Wilcoxon's signed rank tests and exact tests for paired proportions.

RESULTS. Thin sections had smaller PSNR (p < 0.0001). Thin sections had higher grades of artifacts than thick sections, showing significant differences at compression levels of 10:1 (mean score, 0.8 vs 0.4, 0.9 vs 0.1, 0.3 vs 0.0; p < 0.009 for the three readers) and 15:1 (1.9 vs 1.0, 1.9 vs 1.1, 1.5 vs 0.6; p < 0.0001). The percentages of distinguishable pairs (grades 1–3) were greater for thin sections than for thick sections, showing a statistically significant difference at 10:1 for two readers (31% vs 3% and 74% vs 37%; p < 0.006).

CONCLUSION. The lung shows more compression artifacts on thin sections than on thick sections. Section thickness should be taken into consideration when adjusting the compression level for lung CT images.

MATERIALS AND METHODS. We retrospectively reviewed the clinical and CT findings of 49 patients with anthracofibrosis and 35 patients with endobronchial TB diagnosed on the basis of bronchoscopic, microbiologic, and pathologic findings. Forty-five patients with anthracofibrosis and 32 patients with endobronchial TB had bronchostenosis on CT and were enrolled in the analysis. Nine (20%) of 45 patients with anthracofibrosis had coexistent active TB (two, endobronchial TB; six, pulmonary TB; one, TB pleurisy), and 13 (29%) had pulmonary infections other than TB. Two patients with anthracofibrosis and coexistent endobronchial TB were excluded from the analysis. The CT findings were analyzed with emphasis on the pattern, distribution, and location of bronchostenosis and the number of pulmonary lobes involved.

RESULTS. Anthracofibrosis was more common than endobronchial TB among elderly patients (p < 0.05). Statistically significant findings on CT were the pattern of bronchostenosis, presence of main bronchus involvement, and number of pulmonary lobes involved (p < 0.05). Bronchostenosis with anthracofibrosis usually involves multiple lobar or segmental bronchi. The main bronchus, however, tends to be preserved in anthracofibrosis. Most cases of endobronchial TB involve one lobar bronchus and the ipsilateral main bronchus with contiguity in extent.

CONCLUSION. Anthracofibrosis can be differentiated from endobronchial TB on CT. Furthermore, CT is helpful in the diagnosis of anthracofibrosis before bronchoscopy is performed.

SUBJECTS AND METHODS. Sixty-eight patients with 68 pathologically proven SPNs (diameter ≤ 30 mm) underwent dynamic 1.5-T MRI. On time–signal intensity curves generated after bolus injection of contrast material, steepest slope, peak height, and enhancement ratios of signal intensity at the first, second, and fourth minutes were calculated. The relation between dynamic MRI values and microvessel density was analyzed. The morphologic differences between malignant SPNs and active inflammatory SPNs also were analyzed. Threshold dynamic MRI values for differential diagnosis were determined.

RESULTS. The dynamic MRI values of benign SPNs were significantly lower than those of the other SPNs (p < 0.01). The enhancement ratio at the fourth minute for active inflammatory SPNs was significantly higher than that of malignant SPNs (p < 0.01). A high correlation coefficient (r = 0.87, p < 0.001) was found between steepest slope and microvessel density. With steepest slope 1.5%/s or less, benign SPNs were clearly differentiated from other SPNs. With enhancement ratio at the fourth minute 65% or less, malignant SPNs were differentiated from active inflammatory SPNs with high sensitivity (93%) and high specificity (100%).

CONCLUSION. Dynamic MRI values reflect the quantitative and morphologic characteristics of microvessels in SPNs and are a useful tool for differentiating SPNs with little overlap.

MATERIALS AND METHODS. We evaluated posteroanterior and lateral chest images of 21 patients with vertebral fractures, 31 patients with lung nodules, and 10 persons acting as controls. The total number of subjects was 60 because both lesions were present in four patients. Eighteen radiologists were asked to detect vertebral fractures and nodules simultaneously on posteroanterior and lateral images. The radiologists indicated their confidence level ratings regarding the presence or absence of lesions and the most likely location of each lesion on either posteroanterior or lateral images, first without and then with CAD output. The observers' performance was evaluated with use of receiver operating characteristic (ROC) and jackknife free-response ROC curves.

RESULTS. With the CAD scheme, the average area under the ROC curve for detection of vertebral fractures improved from 0.906 to 0.951 (p = 0.002). That for lung nodules also improved, but the improvement was not statistically significant (0.804–0.816, p = 0.297). The figure-of-merit values obtained with the jackknife free-response ROC program improved from 0.585 to 0.680 (p < 0.001) for vertebral fractures and from 0.622 to 0.650 (p = 0.017) for nodules, both results having statistical significance. Average sensitivity in the detection of lesions improved from 59.8% to 69.3% for vertebral fractures and from 64.9% to 67.6% for nodules.

CONCLUSION. In the detection of vertebral fractures and lung nodules on chest images, diagnostic accuracy among radiologists improves with the use of CAD.