Resection of a Large Hemorrhagic Mediastinal Lymphangioma in an Adult Patient: A Radiologic-Pathologic Correlation.

Lymphangiomas are rare benign lesions resulting from abnormal proliferation and sequestration of lymphatic tissues that are disconnected from the rest of the lymphatic system. This is a case of a 50-year-old woman with an unusually large mediastinal lymphangioma complicated by hemorrhage. The substantial mass effect and unstable clinical status necessitated urgent operative management. The use of preoperative multimodality radiologic assessment, including CT and MRI, is illustrated throughout this case. Keywords: CT, MR Imaging, Thorax, Lung © RSNA, 2022.

Histogram-based models on non-thin section chest CT predict invasiveness of primary lung adenocarcinoma subsolid nodules.

109 pathologically proven subsolid nodules (SSN) were segmented by 2 readers on non-thin section chest CT with a lung nodule analysis software followed by extraction of CT attenuation histogram and geometric features. Functional data analysis of histograms provided data driven features (FPC1,2,3) used in further model building. Nodules were classified as pre-invasive (P1, atypical adenomatous hyperplasia and adenocarcinoma in situ), minimally invasive (P2) and invasive adenocarcinomas (P3). P1 and P2 were grouped together (T1) versus P3 (T2). Various combinations of features were compared in predictive models for binary nodule classification (T1/T2), using multiple logistic regression and non-linear classifiers. Area under ROC curve (AUC) was used as diagnostic performance criteria. Inter-reader variability was assessed using Cohen's Kappa and intra-class coefficient (ICC). Three models predicting invasiveness of SSN were selected based on AUC. First model included 87.5 percentile of CT lesion attenuation (Q.875), interquartile range (IQR), volume and maximum/minimum diameter ratio (AUC:0.89, 95%CI:[0.75 1]). Second model included FPC1, volume and diameter ratio (AUC:0.91, 95%CI:[0.77 1]). Third model included FPC1, FPC2 and volume (AUC:0.89, 95%CI:[0.73 1]). Inter-reader variability was excellent (Kappa:0.95, ICC:0.98). Parsimonious models using histogram and geometric features differentiated invasive from minimally invasive/pre-invasive SSN with good predictive performance in non-thin section CT.

Follow Up of Incidental High-Risk Pulmonary Nodules on Computed Tomography Pulmonary Angiography at Care Transitions.

BACKGROUND: Computed tomography pulmonary angiography (CTPA) detects incidental findings that require follow-up. In just over 50% of cases, those incidental findings are pulmonary nodules. Fleischner guidelines recommend that patients with nodules that have a high risk of malignancy should undergo CT follow-up within 3-12 months. OBJECTIVE: We examined the proportion of patients with pulmonary nodules requiring follow up who received repeat imaging within six weeks of the time frame recommended by the radiologist. DESIGN: This retrospective cohort study included all patients who underwent CTPA in the emergency department and inpatient settings at three teaching hospitals in Toronto, Canada between September 1, 2014, and August 31, 2015. Natural language processing software was applied to a linked radiology information system to identify all CTPAs that contained pulmonary nodules. Using manual review and prespecified exclusion criteria, we generated a cohort with possible new lung malignancy eligible for follow-up imaging; then we reviewed available health records to determine whether follow-up had occurred. RESULTS: Of the 1,910 CTPAs performed over the study period, 674 (35.3%) contained pulmonary nodules. Of the 259 patients with new nodules eligible for follow-up imaging, 65 received an explicit suggestion for follow-up by radiology (25.1%). Of these 65 patients, 35 (53.8%) did not receive repeat imaging within the recommended time frame. Explicit mention that follow-up was required in the discharge summary (P = .03), attending an outpatient follow-up visit (P < .001), and younger age (P = .03) were associated with receiving timely follow-up imaging. CONCLUSIONS: Over 50% of patients with new high-risk pulmonary nodules detected incidentally on CTPA did not receive timely follow-up imaging.

Metachronous or synchronous primary lung cancer in the era of computed tomography surveillance.

OBJECTIVES: The purpose of this study was to determine the frequency, characteristics, and survival of second primary lung cancer initially identified as an indeterminate lesion on the original computed tomography scan and then diagnosed during the surveillance period in a prospective study. METHODS: A prospective database of 271 patients enrolled in a surveillance study was updated. Indeterminate lesions present on the original computed tomography at the time of initial primary lung cancer diagnosis that subsequently grew and were diagnosed as cancer were termed "synchronous primary lung cancer." Lesions that were not present on the original computed tomography scan and subsequently diagnosed on surveillance were termed "metachronous primary lung cancer." RESULTS: Thirty patients (11.1%) developed 37 second primary lung cancers over a median surveillance period of 84.7 (range, 15.9-147.6) months. Of these, 15 of 37 (40.5%) were identified as synchronous primary lung cancer, and 22 of 37 (59.5%) were identified as metachronous primary lung cancer. At first identification, ground-glass lesions were identified in 9 of 15 (60%) synchronous primary lung cancers compared with only 5 of 22 (22.7%) of metachronous primary lung cancers (P = .034). Compared with metachronous primary lung cancer, from first identification to diagnosis, synchronous primary lung cancer developed over a longer interval (33.6 vs 7.2 months, P = .001) and had a slower growth rate (0.17 vs 0.45 mm/month, P = .027). The 5-year overall survival from second lung cancer was 73.0%. No significant differences were observed between the synchronous primary lung cancer and metachronous primary lung cancer cohorts in overall survival from initial primary lung cancer (P = .583) or from second lung cancer (P = .966). CONCLUSIONS: Computed tomography surveillance identifies 2 types of curable second lung cancers leading to excellent overall survival.

Chest CT scans are frequently abnormal in asymptomatic patients with newly diagnosed acute myeloid leukemia.

Chest computed tomography (CT) findings of nodules, ground glass opacities, and consolidations are often interpreted as representing invasive fungal infection in individuals with febrile neutropenia. We assessed whether these CT findings were present in asymptomatic individuals with acute myeloid leukemia (AML) at low risk of invasive fungal disease. A retrospective study of consecutive asymptomatic adult patients with newly diagnosed AML over a 2-year period was performed at a tertiary care oncology center. Radiology reports of baseline chest CTs were reviewed. Of 145 CT scans, the majority (88%) had pulmonary abnormalities. Many (70%) had one or both of unspecified opacities (52%) and nodules (49%). Ground glass opacities (18%) and consolidations (12%) occurred less frequently. Radiologists suggested pneumonia as a possible diagnosis in 32% (n = 47) of scans. Chest CT may result in over-diagnosis of invasive fungal disease in individuals with febrile neutropenia if interpreted without correlation to the patients' clinical status.

Randomized controlled trial of relaxation music to reduce heart rate in patients undergoing cardiac CT.

OBJECTIVES: To evaluate the heart rate lowering effect of relaxation music in patients undergoing coronary CT angiography (CCTA), pulmonary vein CT (PVCT) and coronary calcium score CT (CCS). METHODS: Patients were randomised to a control group (i.e. standard of care protocol) or to a relaxation music group (ie. standard of care protocol with music). The groups were compared for heart rate, radiation dose, image quality and dose of IV metoprolol. Both groups completed State-Trait Anxiety Inventory anxiety questionnaires to assess patient experience. RESULTS: One hundred and ninety-seven patients were recruited (61.9 % males); mean age 56y (19-86 y); 127 CCTA, 17 PVCT, 53 CCS. No significant difference in heart rate, radiation dose, image quality, metoprolol dose and anxiety scores. 86 % of patients enjoyed the music. 90 % of patients in the music group expressed a strong preference to have music for future examinations. The patient cohort demonstrated low anxiety levels prior to CT. CONCLUSION: Relaxation music in CCTA, PVCT and CCS does not reduce heart rate or IV metoprolol use. Patients showed low levels of anxiety indicating that anxiolytics may not have a significant role in lowering heart rate. Music can be used in cardiac CT to improve patient experience. KEY POINTS: • Relaxation music does not reduce heart rate in cardiac CT • Relaxation music does not reduce beta-blocker use in cardiac CT • Relaxation music has no effect on cardiac CT image quality • Low levels of anxiety are present in patients prior to cardiac CT • Patients enjoyed the relaxation music and this results in improved patient experience.

Low-dose computed tomography volumetry for subtyping chronic lung allograft dysfunction.

BACKGROUND: The long-term success of lung transplantation is challenged by the development of chronic lung allograft dysfunction (CLAD) and its distinct subtypes of bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). However, the current diagnostic criteria for CLAD subtypes rely on total lung capacity (TLC), which is not always measured during routine post-transplant assessment. Our aim was to investigate the utility of low-dose 3-dimensional computed tomography (CT) lung volumetry for differentiating RAS from BOS. METHODS: This study was a retrospective evaluation of 63 patients who had developed CLAD after bilateral lung or heart‒lung transplantation between 2006 and 2011, including 44 BOS and 19 RAS cases. Median post-transplant follow-up was 65 months in BOS and 27 months in RAS. The median interval between baseline and the disease-onset time-point for CT volumetry was 11 months in both BOS and RAS. Chronologic changes and diagnostic accuracy of CT lung volume (measured as percent of baseline) were investigated. RESULTS: RAS showed a significant decrease in CT lung volume at disease onset compared with baseline (mean 3,916 ml vs 3,055 ml when excluding opacities, p < 0.0001), whereas BOS showed no significant post-transplant change (mean 4,318 ml vs 4,396 ml, p = 0.214). The area under the receiver operating characteristic curve of CT lung volume for differentiating RAS from BOS was 0.959 (95% confidence interval 0.912 to 1.01, p < 0.0001) and the calculated accuracy was 0.938 at a threshold of 85%. CONCLUSION: In bilateral lung or heart‒lung transplant patients with CLAD, low-dose CT volumetry is a useful tool to differentiate patients who develop RAS from those who develop BOS.

Safety and Efficacy of Modified Preoperative Lung Nodule Microcoil Localization Without Pleural Marking: A Pilot Study.

PURPOSE: The purpose of this pilot study was to evaluate the safety and efficacy of preoperative computed tomography (CT)-guided percutaneous microcoil lung nodule localization without pleural marking compared with the established technique with pleural marking. MATERIALS AND METHODS: Sixty-three consecutive patients (66.7% female, mean age 61.6±11.4 y) with 64 lung nodules resected between October 2008 and January 2014 were retrospectively evaluated. Of the nodules, 29.7% (n=19) had microcoil deployment with pleural marking (control group) and 70.3% (n=45) had microcoil deployment without pleural marking (pilot group). Clinical, pathologic, and imaging characteristics, radiation dose, CT procedure and operating room time, and complete resection and complication rates were compared between the pilot and control groups. RESULTS: There was no significant difference in nodule size (P=0.552) or distance from the pleural surface (P=0.222) between the pilot and control groups. However, mean procedure duration (53.6±18.3 vs. 72.8±25.3 min, P=0.001) and total effective radiation dose (5.1±2.6 vs. 7.1±4.9 mSv, P=0.039) were significantly lower in the pilot group compared with the control group. CT procedure-related complications (P=0.483) [including pneumothoraces (P=0.769) and pulmonary hemorrhage (P=1.000)], operating room time (P=0.926), complete resection rates (P=0.520), intraoperative complications (P=0.549), and postoperative complications (P=1.000) were similar between the pilot and control groups. CONCLUSIONS: Preoperative CT-guided lung nodule microcoil localization performed without visceral pleural marking appears to decrease the CT procedure time and radiation dose while maintaining equivalent complete resection rates and procedural and surgical complications, when compared with microcoil localization performed with pleural marking.

Optimal image reconstruction for detection and characterization of small pulmonary nodules during low-dose CT.

OBJECTIVES: To optimize the slice thickness/overlap parameters for image reconstruction and to study the effect of iterative reconstruction (IR) on detectability and characterization of small non-calcified pulmonary nodules during low-dose thoracic CT. MATERIALS AND METHODS: Data was obtained from computer simulations, phantom, and patient CTs. Simulations and phantom CTs were performed with 9 nodules (5, 8, and 10 mm with 100, -630, and -800 HU). Patient data were based on 11 ground glass opacities (GGO) and 9 solid nodules. For each analysis the nodules were reconstructed with filtered back projection and IR algorithms using 10 different combinations of slice thickness/overlap (0.5-5 mm). The attenuation (CT#) and the contrast to noise ratio (CNR) were measured. Spearman's coefficient was used to correlate the error in CT# measurements and slice thickness. Paired Student's t test was used to measure the significance of the errors. RESULTS: CNR measurements: CNR increases with increasing slice thickness/overlap for large nodules and peaks at 4.0/2.0 mm for smaller ones. Use of IR increases the CNR of GGOs by 60 %. CT# measurements: Increasing slice thickness/overlap above 3.0/1.5 mm results in decreased CT# measurement accuracy. CONCLUSION: Optimal detection of small pulmonary nodules requires slice thickness/overlap of 4.0/2.0 mm. Slice thickness/overlap of 2.0/2.0 mm is required for optimal nodule characterization. IR improves conspicuity of small ground glass nodules through a significant increase in nodule CNR. KEY POINTS: • Slice thickness/overlap affects the accuracy of pulmonary nodule detection and characterization. • Slice thickness ≥3 mm increases the risk of misclassifying small nodules. • Optimal nodule detection during low-dose CT requires 4.0/2.0-mm reconstructions. • Optimal nodule characterization during low-dose CT requires 2.0/2.0-mm reconstructions. • Iterative reconstruction improves the CNR of ground glass nodules by 60 %.

Minimal-dose computed tomography is superior to chest x-ray for the follow-up and treatment of patients with resected lung cancer.

OBJECTIVES: A minimal-dose computed tomography scan of the thorax (MnDCT) delivers a radiation dose comparable with a chest x-ray (CXR). We hypothesized that in patients with completely resected lung cancer, surveillance with MnDCT, when compared with CXR, leads to earlier detection and a higher rate of treatment of new or recurrent lung cancer. METHODS: After lung cancer resection, patients prospectively were enrolled for surveillance with MnDCT and CXR at 3, 6, 12, 18, 24, 36, 48, and 60 months. Images were interpreted by different blinded radiologists. When new or recurrent cancer was suspected, standard-dose CT and/or a tissue biopsy were performed for confirmation. RESULTS: Between 2007 and 2012, 271 patients were included and 1137 pairs of CXR and MnDCT were analyzed. MnDCT was more sensitive (94% vs 21%; P < .0001) and had a higher negative predictive value (99% vs 96%; P = .007) than CXR for the diagnosis of new or recurrent lung cancer. The prevalence of new or recurrent lung cancer was 23.2% (63 of 271), of whom 78% (49 of 63) had asymptomatic disease. The majority of asymptomatic patients (75%; 37 of 49) were treated with curative intent and had a median survival of 69 months. The remainder of patients received palliative treatment (24%; 12 of 49) and had a median survival of 25 months (P < .0001). CONCLUSIONS: After curative resection of lung cancer, MnDCT is superior to CXR for the detection of new or recurrent lung cancer. The majority of new or recurrent cancer was detected by MnDCT at an asymptomatic phase, allowing for curative treatment, leading to a long survival.

Beyond lung cancer: a strategic approach to interpreting screening computed tomography scans on the basis of mortality data from the National Lung Screening Trial.

Low-dose computed tomography screening in older patients with a heavy-smoking history can be viewed as an opportunity to screen for smoking-related illnesses and not just for lung cancer. Within the National Lung Screening Trial, 24.1% of all deaths were attributed to lung cancer, but there were significant competing causes of mortality in this patient population. Cardiovascular illness caused 24.8% of deaths. Other neoplasms were listed as the cause of death in 22.3%, and respiratory illness was the cause of death in 10.4%. All of these illnesses might be attributed to smoking. Low-dose computed tomography of the thorax may provide information about these diseases, which could be used to guide therapeutic intervention and, hopefully, alter the courses of these diseases. Information about coronary artery calcification, chronic obstructive pulmonary disease, and potential extrapulmonary malignancy should be provided in the report of the screening examination. This must be balanced against the risk of the burden of false-positive findings and the costs, both psychological and financial, associated with additional investigative evaluations.

Assessment of right ventricular volumes and function using cardiovascular magnetic resonance cine imaging after atrial redirection surgery for complete transposition of the great arteries.

Cardiovascular magnetic resonance (CMR) imaging is the reference standard for measurement of right ventricular (RV) volumes and function. To date, no study has compared methods of data acquisition and analysis by CMR for adults with a systemic RV. Our objective was to evaluate RV size and function using axial and short axis views in adults post atrial switch (Mustard) surgery. A total of 34 adults (20 male, mean age at CMR 32 ± 6 years) were identified at our centre. Volumes, RV end-diastolic (EDV) and end-systolic (ESV) were measured in short axis and axial orientations by two independent experienced readers, blinded to clinical and CMR data. Intra and interobserver measurements in each view were compared using Bland-Altman plots and intraclass correlation coefficients (ICC). Although mean volumes were larger in the axial as compared with the short axis view [RVEDV 247 ± 67 vs. 233 ± 54 ml (p = 0.002) and RVESV 148 ± 54 vs. 136 ± 50 ml (p = 0.001)], mean RV ejection fractions (EF) were similar [41 ± 9 % vs. 43 ± 12 % (p = 0.13)]. Bland-Altman plots demonstrated better agreement for axial measures of RVEDV and right ventricular ejection fraction (RVEF) within and between observers. Similarly, ICC values were stronger for axial as compared with short axis volumes and function-intraobserver RVEDV 0.99 (0.98-0.99) versus 0.96 (0.92-0.98) and RVEF 0.96 (0.93-0.98) versus 0.90 (0.82-0.95); interobserver RVEDV 0.97 (0.94-0.98) versus 0.90 (0.73-0.95) and RVEF 0.85 (0.53-0.94) versus 0.82 (0.67-0.90). Axially derived measurements of RV volumes and function have better agreement and reproducibility as compared with short axis values; whereas axial volumes tend to be larger, RVEF is not significantly different between the two methods.

Failed heart rate control with oral metoprolol prior to coronary CT angiography: effect of additional intravenous metoprolol on heart rate, image quality and radiation dose.

The purpose of this study was to evaluate the effect of intravenous (i.v.) metoprolol after a suboptimal heart rate (HR) response to oral metoprolol (75-150 mg) on HR control, image quality (IQ) and radiation dose during coronary CTA using 320-MDCT. Fifty-three consecutive patients who failed to achieve a target HR of < 60 bpm after an oral dose of metoprolol and required supplementary i.v. metoprolol (5-20 mg) prior to coronary CTA were evaluated. Patients with HR < 60 bpm during image acquisition were defined as responders (R) and those with HR ≥ 60 bpm as non-responders (NR). Two observers assessed IQ using a 3-point scale (1-2, diagnostic and 3, non-diagnostic). Effective dose (ED) was estimated using dose-length product and a 0.014 mSV/mGy.cm conversion factor. Baseline characteristics and HR on arrival were similar in the two groups. 58% of patients didn't achieve the target HR after receiving i.v. metoprolol (NR). R had a significantly higher HR reduction after oral (mean HR 63.9 ± 4.5 bpm vs. 69.6 ± 5.6 bpm) (p < 0.005) and i.v. (mean HR 55.4 ± 3.9 bpm vs. 67.4 ± 5.3 bpm) (p < 0.005) doses of metoprolol. Studies from NR showed a significantly higher ED in comparison to R (8.0 ± 2.9 vs. 6.1 ± 2.2 mSv) (p = 0.016) and a significantly higher proportion of non-diagnostic coronary segments (9.2 vs. 2.5%) (p < 0.001). 58% of patients who do not achieve a HR of <60 bpm prior to coronary CTA with oral fail to respond to additional i.v. metoprolol and have studies with higher radiation dose and worse image quality.

Image quality and radiation dose of pulmonary CT angiography performed using 100 and 120 kVp.

OBJECTIVE: The objective of our study was to compare image quality and radiation dose of pulmonary CT angiography (CTA) performed in the same patient cohort using tube potentials of 100 and 120 kVp. MATERIALS AND METHODS: The study group for this retrospective study was 32 patients (22 women, 10 men) with a mean age of 57 years (age range, 28-83 years; body weight < 100 kg). Patients underwent pulmonary CTA studies performed using 120 and 100 kVp while other scanning parameters were kept constant. Two observers measured image signal and image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), and SNR dose and CNR dose. Two additional observers performed qualitative image quality analysis using a 5-point grading scale (5 = excellent). RESULTS: The reduction in tube potential caused image signal to increase by 29% (p < 0.0001), image noise to increase by 68% (p < 0.0001), CNR dose to decrease by 0.8% (p = 0.91) and SNR to decrease by 24% (p = 0.0002) and CNR by 20% (p = 0.0019). Radiation dose (dose-length product) was decreased by 37% to 379.26 mGy × cm at 100 kVp from 604.46 mGy × cm at 120 kVp (p < 0.0001). The median pulmonary arteries image quality scores for observers 1 and 2, respectively, were as follows at 100 kVp: main, 5 and 5; lobar, 5 and 4.5; and segmental, 5 and 4. At 120 kVp, the median image quality scores for observers 1 and 2 were as follows: main, 5 and 5; lobar, 5 and 5; segmental, 4 and 4. A Wilcoxon test analysis indicated no significant difference in image quality between the studies (main, p = 0.59; lobar, p = 0.88; segmental, p = 0.79). CONCLUSION: Pulmonary CTA can be performed using a tube potential of 100 kVp in patients who weigh less than 100 kg (220 lb). Reducing the tube potential from 120 to 100 kVp results in a 37% reduction in radiation dose without a significant impact on diagnostic image quality.

Optimal imaging protocols for lung cancer staging: CT, PET, MR imaging, and the role of imaging.

Chest radiography, the most commonly performed imaging technique for the detection of lung disease, is limited in accurately detecting early lung cancer. The main imaging modality for the staging of lung cancer is computed tomography (CT), supplemented by positron emission tomography (PET), usually as a hybrid technique in conjunction with CT (PET/CT). Magnetic resonance (MR) imaging is a useful diagnostic tool for specific indications and has the advantage of not using ionizing radiation. This article discusses the optimal imaging protocols for lung cancer staging using CT, PET (PET/CT), and MR imaging, and the role of imaging in patient management.

CT screening for lung cancer: implication of lung biopsy recommendations.

OBJECTIVE: The purpose of this article is to address the implications of invasive diagnostic procedures recommended by a lung cancer screening protocol. In particular, we assess how many invasive procedures were recommended for benign nodules. MATERIALS AND METHODS: Between 2003 and 2009, 4782 high-risk current and former smokers were enrolled in a lung cancer screening study. A helical low-dose CT of the chest was performed. Morphologic features targeted were parenchymal nodules. The indication for biopsy was made according to the diagnostic algorithm provided by the International Early Lung Cancer Action Program. We recorded the time points of biopsy recommendation; shape, size, and growth of nodules; types of diagnostic procedures; complication rates; and final pathologic diagnosis. RESULTS: A total of 128 diagnostic biopsies were recommended for suspicious nodules, and 127 biopsies were performed, including 110 percutaneous CT-guided fine-needle aspiration biopsies (FNABs), nine video-assisted thoracoscopic surgery (VATS) resections, seven bronchoscopies, and one ultrasound-guided biopsy of a lymph node. Of 110 FNABs, 24 had unsatisfactory results, 13 of which were referred for secondary diagnostic VATS resection. The indication for biopsy was made on the basis of shape in 48% of cases (62/128), growth on follow-up in 40% of cases (51/128), and the appearance of new nodules in 12% of cases (15/128). In total, 104 of 124 biopsies (84%) were correctly indicated (true-positive recommendation) for malignancy, 20 were benign (false-positive) (16%), and final results are pending for four cases. The overall false-positive recommendation rate was 0.42% (20/4782); 11.6% of FNABs (16/128) and 3.6% of VATS (5/128) revealed benign nodules, corresponding to an overall false-positive rate of 0.33% for FNAB (16/4782) and 0.10% for VATS (5/4782). CONCLUSION: The recommended biopsy procedures for screen-detected suspicious pulmonary nodules resulted in a low intervention rate for benign nodules. This rate is minimal when we followed a research protocol that relies on shape and growth.

Screen-detected lung cancer: a retrospective analysis of CT appearance.

RATIONALE AND OBJECTIVES: The aim of this study was to retrospectively evaluate characteristics of lung cancers diagnosed in a low-dose computed tomographic lung cancer screening study. MATERIALS AND METHODS: As part of the International Early Lung Cancer Action Program, a cohort of 4782 at-risk participants were screened. A total of 86 cancers in 84 individuals were detected and evaluated for location, morphology (density, border), size, histology, stage at diagnosis, treatment, and survival. Follow-up imaging for computation of growth rates was available in 41 cases. RESULTS: Eighty-six cancers were detected in 84 individuals (60 women, 24 men). Of these, seven (8%) were incidence cancers. Most cancers were radiologically described as solid (n = 52 [61%]). The median tumor size was 18 × 13 mm (range, 6-56 mm). Histopathologic diagnoses revealed 10 (11.6%) bronchoalveolar carcinomas, 55 (64%) adenocarcinomas, 11 (12.8%) squamous-cell carcinomas, two (2.3%) large-cell carcinomas, three (3.5%) carcinoids, and five (5.8%) small-cell lung cancers. Of the 41 cases with follow-up computed tomographic scans, 36 nodules had increased in size. The mean doubling time for all cancers was 259 days (median, 154 days). In women (n = 25), the mean doubling time was 313 days (median, 156 days), while in men (n = 11), the mean doubling time was 137 days (median, 92 days). Overall, 55 lung cancers (68%) were stage I. Most cancers (n = 62 [73%]) were surgically resected. CONCLUSIONS: In this cohort, screening detected lung cancer in early treatable stages, and women had more slow-growing adenocarcinomas than men. Most screen-detected lung cancers were surgically resectable.

Assessing the impact of incidental findings in a lung cancer screening study by using low-dose computed tomography.

PURPOSE: To assess the prevalence and nature of incidental findings (IF) seen in low-dose computed tomographies (LDCT) from a lung cancer screening study for at-risk individuals. MATERIALS AND METHODS: Radiology reports from LDCTs of 4073 participants of a lung cancer screening study were retrospectively reviewed for findings other than lung nodules, that is, IFs, which were regarded as actionable. The frequency, nature, and expected cost of these IFs, and their anticipated follow-up were estimated. RESULTS: There were 880 IFs described in 782 study participants (19%); the median age of the participants was 62 years (range, 46-80 years). More IFs were found in men (55%) than in women. The majority of these findings were noncardiovascular (76%), for which imaging was suggested for 74%. There were 7 severe IFs (0.8%) that merited immediate attention. Seven known cancers were diagnosed from follow-ups of the IFs. The majority of IFs (n = 486 [55%]) would require imaging follow-up if clinically indicated, with an estimated total a cost of CAN$45,500 to CAN$51,000 to provide initial diagnostic workup. CONCLUSION: IFs on lung cancer screening studies are not uncommon and frequently require imaging or other follow-up for definitive diagnoses and to assess their clinical relevance. The implication of IFs has to be considered when determining a cost-effective and ethical protocol for the utilisation of LDCT in a high-risk population.

Diagnostic performance of a prototype dual-energy chest imaging system ROC analysis.

RATIONALE AND OBJECTIVES: To assess the performance of an experimental prototype dual-energy (DE) chest imaging system in comparison to digital radiography (DR) in detection and characterization of lung lesions using receiver-operating characteristic (ROC) tests. MATERIALS AND METHODS: A cohort of 129 patients (80 M, 49 F; mean age, 64.8 years) was drawn from a trial of patients referred for percutaneous biopsy of a lung lesion. DR and DE images were acquired of each patient (posteroanterior view) before biopsy using a prototype system developed in our laboratory. The system incorporated a flat-panel detector and previously reported imaging techniques optimized such that the total dose for the DE image was equivalent to that of a DR acquisition. Each DE image was decomposed to three components (soft-tissue, bone, and composite "equivalent radiograph") by log subtraction with optimized noise reduction techniques. ROC tests were performed to evaluate the diagnostic performance of DR imaging in comparison to DE for nodule detection, with 258 left/right "half-chest" images derived from the 129 cases to give a roughly equal number of disease and normal cases. Five chest radiologists scored 258 half-chest DE and 258 half-chest DR (516 in total) images on a 5-point scale, and results (including ROC and area under the curve [AUC]) were analyzed using the ROCkit toolkit. Statistical significance in the observed differences was evaluated in terms of P values determined by a z test. Performance was analyzed for all cases pooled (258 DE vs. 258 DR images) and by retrospective stratification of the data according to nodule size, density, gender, lung region, and chest thickness. RESULTS: For results pooled over the entire cohort, there was no significant difference in ROC performance between DE and DR (AUC(DE) = 0.795 AUC(DR) = 0.789; P = .696). This finding is believed to be due to a large portion of lesions that were fairly conspicuous in either modality. In retrospective analysis of subgroups, a significant advantage was measured for DE imaging of small nodules (<1 cm diameter; AUC(DE) = 0.778; AUC(DR) = 0.706; P = .056), for nodules located in the right upper lobe (AUC(DE) = 0.836; AUC(DR) = 0.779; P = .003), and nodules located in right lower lobe (AUC(DE) = 0.804; AUC(DR) = 0.752; P = .054). DE imaging provided a clinically significant differential diagnosis in approximately one third of patients (49/158) (ie, disease cases in which the lesion was correctly identified in DE [(ROC rating > or =3], but missed in DR [ROC rating < or =2]). DE imaging also appeared to provide more definitive diagnosis (ie, a greater proportion of ROC ratings = 5 and 1 for identification of disease and normal cases, respectively), which presumably translates to increased confidence and a steeper ROC curve (even if the AUC are the same). CONCLUSIONS: DE imaging at dose equivalent to DR exhibited similar overall ROC performance to DR, although the radiologists noted qualitatively improved visualization (eg, improved characterization of lesion margins, visibility of calcifications and rib fractures). DE imaging demonstrated significant improvement in diagnostic performance for specific subgroups, including subcentimeter lung lesions and lesions in the right upper lobe, each of which is a potentially important factor in detecting early-stage malignancy.

Dynamic airway evaluation with volume CT: initial experience.

PURPOSE: The purpose of the study was to prospectively establish the use of a novel multidetector computed tomography unit (MDCT) with 320 x 0.5 detector rows for the evaluation of tracheomalacia by using a dynamic expiratory low-dose technique. METHODS: Six adult patients (5 men, 1 woman; mean age, 53.7 years [37-70 years]) referred for a clinical suspicion of tracheomalacia were studied on a 320-row MDCT unit by using the following parameters: 120 kVp, 40-50 mA, 0.5-second gantry rotation, and z-axis coverage of 160 mm sufficient to cover the thoracic trachea to the proximal bronchi. Image acquisition occurred during a forceful exhalation. The image data set was subject to the following analyses: cross-sectional area of airway lumen at 4 predefined locations (thoracic inlet, aortic arch, carina, and bronchus intermedius) and measurement of airway volume. RESULTS: All 6 patients had evidence of tracheomalacia, the proximal trachea collapsed at a later phase of expiration (3-4 seconds) than the distal trachea (2-3 seconds). The most common region of airway collapse occurred at the level of the aortic arch (5/6 [83%]), Three patients (50%) had diffuse segmental luminal narrowing that involved the tracheobronchial tree. The radiation dose (estimated dose length product, computed tomography console) measured 293.9 mGy in 1 subject and 483.5 mGy in 5 patients. CONCLUSIONS: Four-dimensional true isophasic and isovolumetric imaging of the central airways by using 320-row MDCT is a viable technique for the diagnosis of tracheomalacia; it provides a comprehensive assessment of airways dynamic.