Computer-aided classification of visual ventilation patterns in patients with chronic obstructive pulmonary disease at two-phase xenon-enhanced CT.

OBJECTIVE: To evaluate the technical feasibility, performance, and interobserver agreement of a computer-aided classification (CAC) system for regional ventilation at two-phase xenon-enhanced CT in patients with chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: Thirty-eight patients with COPD underwent two-phase xenon ventilation CT with resulting wash-in (WI) and wash-out (WO) xenon images. The regional ventilation in structural abnormalities was visually categorized into four patterns by consensus of two experienced radiologists who compared the xenon attenuation of structural abnormalities with that of adjacent normal parenchyma in the WI and WO images, and it served as the reference. Two series of image datasets of structural abnormalities were randomly extracted for optimization and validation. The proportion of agreement on a per-lesion basis and receiver operating characteristics on a per-pixel basis between CAC and reference were analyzed for optimization. Thereafter, six readers independently categorized the regional ventilation in structural abnormalities in the validation set without and with a CAC map. Interobserver agreement was also compared between assessments without and with CAC maps using multirater κ statistics. RESULTS: Computer-aided classification maps were successfully generated in 31 patients (81.5%). The proportion of agreement and the average area under the curve of optimized CAC maps were 94% (75/80) and 0.994, respectively. Multirater κ value was improved from moderate (κ = 0.59; 95% confidence interval [CI], 0.56-0.62) at the initial assessment to excellent (κ = 0.82; 95% CI, 0.79-0.85) with the CAC map. CONCLUSION: Our proposed CAC system demonstrated the potential for regional ventilation pattern analysis and enhanced interobserver agreement on visual classification of regional ventilation.

Percutaneous transthoracic needle biopsy of small (≤ 1 cm) lung nodules under C-arm cone-beam CT virtual navigation guidance.

OBJECTIVES: To describe our initial experience with percutaneous transthoracic needle biopsy (PCNB) of small (≤1 cm) lung nodules using a cone-beam computed tomography (CBCT) virtual navigation guidance system in 105 consecutive patients. METHODS: One hundred and five consecutive patients (55 male, 50 female; mean age, 62 years) with 107 small (≤1 cm) lung nodules (mean size, 0.85 cm ± 0.14) underwent PCNBs under CBCT virtual-navigation guidance system and constituted our study population. Procedural details-including radiation dose, sensitivity, specificity, diagnostic accuracy and complication rates of CBCT virtual navigation guided PCNBs-were described. RESULTS: The mean number of pleural passages with the coaxial needle, biopsies, CT acquisitions, total procedure time, coaxial introducer dwelling time, and estimated radiation exposure during PCNBs were 1.03 ± 0.21, 3.1 ± 0.7, 3.4 ± 1.3, 10.5 min ± 3.2 and 7.2 min ± 2.5, and 5.72 mSv ± 4.19, respectively. Sixty nodules (56.1 %) were diagnosed as malignant, 38 (35.5 %) as benign and nine (8.4 %) as indeterminate. The sensitivity, specificity, and diagnostic accuracy of CBCT virtual-navigation-guided PCNB for small (≤1 cm) nodules were 96.7 % (58/60), 100 % (38/38) and 98.0 % (96/98), respectively. Complications occurred in 13 (12.1 %) cases; pneumothorax in seven (6.5 %) and haemoptysis in six (5.6 %). CONCLUSION: CBCT virtual-navigation-guided PCNB is a highly accurate and safe diagnostic method for small (≤1 cm) nodules.

CT-guided percutaneous transthoracic localization of pulmonary nodules prior to video-assisted thoracoscopic surgery using barium suspension.

OBJECTIVE: To describe our initial experience with CT-guided percutaneous barium marking for the localization of small pulmonary nodules prior to video-assisted thoracoscopic surgery (VATS). MATERIALS AND METHODS: From October 2010 to April 2011, 10 consecutive patients (4 men and 6 women; mean age, 60 years) underwent CT-guided percutaneous barium marking for the localization of 10 small pulmonary nodules (mean size, 7.6 mm; range, 3-14 mm): 6 pure ground-glass nodules, 3 part-solid nodules, and 1 solid nodule. A 140% barium sulfate suspension (mean amount, 0.2 mL; range, 0.15-0.25 mL) was injected around the nodules with a 21-gauge needle. The technical details, surgical findings and pathologic features associated with barium localizations were evaluated. RESULTS: All nodules were marked within 3 mm (mean distance, 1.1 mm; range, 0-3 mm) from the barium ball (mean diameter, 9.6 mm; range, 8-16 mm) formed by the injected barium suspension. Pneumothorax occurred in two cases, for which one needed aspiration. However, there were no other complications. All barium balls were palpable during VATS and visible on intraoperative fluoroscopy, and were completely resected. Both the whitish barium balls and target nodules were identifiable in the frozen specimens. Pathology revealed one invasive adenocarcinoma, five adenocarcinoma-in-situ, two atypical adenomatous hyperplasias, and two benign lesions. In all cases, there were acute inflammations around the barium balls which did not hamper the histological diagnosis of the nodules. CONCLUSION: CT-guided percutaneous barium marking can be an effective, convenient and safe pre-operative localization procedure prior to VATS, enabling accurate resection and diagnosis of small or faint pulmonary nodules.

Low-dose computed tomography of the chest using iterative reconstruction versus filtered back projection: comparison of image quality.

OBJECTIVE: The purpose of this study was to compare image quality of iterative reconstruction (IR) to filtered back projection (FBP) in low-dose computed tomography of the chest. METHODS: Forty-three consecutive patients were retrospectively enrolled. Eight series of images were reconstructed using FBP and 7 levels of IR in each subject. Image noise, signal-to-noise ratio (SNR), and SNR improvement were measured. Two radiologists evaluated subjective artifact, image artificiality, and subjective overall image quality with 4- or 5-point scales. RESULTS: Iterative reconstruction showed significantly lower image noise (135.5 ± 36.6 vs 219.9 ± 40.9) and higher SNR (0.36 ± 0.12 vs 0.21 ± 0.05) than FBP (P < 0.001). Signal-to-noise ratio improvement was 72.4% ± 44.9%. Subjective artifact of FBP was significantly higher than IR images (P < 0.001). Image artificiality of IR was significantly higher than that of FBP (P < 0.001). Overall, subjective image quality was poor in FBP and acceptable or good in IR. CONCLUSIONS: With the use of IR, low-dose computed tomography of the chest would achieve less image noise and better image quality compared to the FBP.

Impact of sputum gross appearance and volume on smear positivity of pulmonary tuberculosis: a prospective cohort study.

BACKGROUND: Although checking specimen quality upon sputum collection for acid-fast smear of suspected tuberculosis (TB) cases is recommended, this procedure is based on expert opinion. The purpose of this study was to elucidate the impact of sputum gross appearance and volume on smear positivity among patients with suspected pulmonary TB, according to sex. METHODS: From November 2010 through June 2011, we enrolled consecutive patients suspected to have active pulmonary TB. The association of sputum gross appearance and volume with smear positivity, along with other variables possibly affecting smear positivity such as symptoms, disease extent, and cavity on chest radiograph, were investigated. RESULTS: Among 2,439 patients undergoing TB examination, 170 (113 men, 57 women) with active pulmonary TB were enrolled. They submitted 492 sputa. There were 73 smear-positive patients (42.9%) and 164 smear-positive sputa (33.3%). While gross appearance was associated with smear positivity in both sexes (purulent or blood-tinged sputum (rather than mucoid sputum or saliva); odds ratio (OR), 2.05, 95% confidence interval (CI), 1.21-3.47 in men; OR, 2.78, 95% CI, 1.23-6.26 in women), the amount of sputum specimens was associated with smear positivity in only female patients (≥4 ml versus <4 ml; OR, 4.96, 95% CI, 1.98-12.37). CONCLUSIONS: Sputum gross appearance and volume were associated with smear positivity. A volume of 4 ml seems to be the the minimum sputum volume acceptable for smear microscopy in females suspected of TB. Those suspected of TB should be encouraged to expectorate grossly qualified sputum specimens.

Computer-aided nodule detection and volumetry to reduce variability between radiologists in the interpretation of lung nodules at low-dose screening computed tomography.

OBJECTIVE: The aim of this study was to evaluate whether a computer-aided diagnosis (CAD) system improves interobserver agreement in the interpretation of lung nodules at low-dose computed tomography (CT) screening for lung cancer. MATERIALS AND METHODS: Baseline low-dose screening CT examinations from 134 participants enrolled in the National Lung Screening Trial were reviewed by 7 chest radiologists. All participants consented to the use of their deidentified images for research purposes. Screening results were classified as positive when noncalcified nodules larger than 4 mm in diameter were present. Follow-up evaluation was recommended according to the nodule diameter: 4 mm or smaller, more than 4 to 8 mm, and larger than 8 mm. When multiple nodules were present, recommendations were based on the largest nodule. Readers initially assessed the nodule presence visually and measured the average nodule diameter manually. Revision of their decisions after reviewing the CAD marks and size measurement was allowed. Interobserver agreement evaluated using multirater κ statistics was compared between initial assessment and that with CAD. RESULTS: Multirater κ values for the positivity of the screening results and follow-up recommendations were improved from moderate (κ = 0.53-0.54) at initial assessment to good (κ = 0.66-0.67) after reviewing CAD results. The average percentage of agreement between reader pairs on the positivity of screening results and follow-up recommendations per case was also increased from 77% and 72% at initial assessment to 84% and 80% with CAD, respectively. CONCLUSION: Computer-aided diagnosis may improve the reader agreement on the positivity of screening results and follow-up recommendations in the assessment of low-dose screening CT.

Serial computed tomography and magnetic resonance imaging findings of biphasic acute hemorrhagic leukoencephalitis localized to the brain stem and cerebellum.

Acute hemorrhagic leukoencephalitis (AHL) is a rare and usually fatal disease characterized by an acute onset of neurological abnormalities. We describe the case of a 37-year-old man with biphasic AHL with a focus on the rare involvement of the brain stem and cerebellum. Initial computed tomography (CT) and magnetic resonance imaging revealed two hemorrhagic foci in the left middle cerebellar peduncle. After 15 days multifocal hematomas in the contralateral cerebellar hemisphere were imaged using CT. The pathological diagnosis was AHL. Following high-dose steroid treatment, the patient recovered with minor neurological sequelae.

Findings from CT, MRI, and PET/CT of a primary malignant melanoma arising in a spinal nerve root.

Primary spinal malignant melanoma is an extremely rare condition. We here describe a case of a 71-year-old Asian female presenting with left upper extremity tingling sensation. Computed tomography (CT) showed a homogeneously enhanced mass occupying the left neural foramen at the C6-7 level. Magnetic resonance imaging revealed enhanced mass in intra- and extradural space compressing the spinal cord at this level. It also widened the neural foramen mimicking neurofibroma or schwannoma. Partial resection of the mass was performed. Pathologic diagnosis of the mass was malignant melanoma. Postoperative whole body positron emission tomography/CT scan demonstrated an intense (18)F-FDG uptake at the residual mass site without abnormal uptake at other sites in the body.