Right main pulmonary artery distensibility on dynamic ventilation CT and its association with respiratory function.

BACKGROUND: Heartbeat-based cross-sectional area (CSA) changes in the right main pulmonary artery (MPA), which reflects its distensibility associated with pulmonary hypertension, can be measured using dynamic ventilation computed tomography (DVCT) in patients with and without chronic obstructive pulmonary disease (COPD) during respiratory dynamics. We investigated the relationship between MPA distensibility (MPAD) and respiratory function and how heartbeat-based CSA is related to spirometry, mean lung density (MLD), and patient characteristics. METHODS: We retrospectively analyzed DVCT performed preoperatively in 37 patients (20 female and 17 males) with lung cancer aged 70.6 ± 7.9 years (mean ± standard deviation), 18 with COPD and 19 without. MPA-CSA was separated into respiratory and heartbeat waves by discrete Fourier transformation. For the cardiac pulse-derived waves, CSA change (CSAC) and CSA change ratio (CSACR) were calculated separately during inhalation and exhalation. Spearman rank correlation was computed. RESULT: In the group without COPD as well as all cases, CSACR exhalation was inversely correlated with percent residual lung volume (%RV) and RV/total lung capacity (r = -0.68, p = 0.003 and r = -0.58, p = 0.014). In contrast, in the group with COPD, CSAC inhalation was correlated with MLDmax and MLD change rate (MLDmax/MLDmin) (r = 0.54, p = 0.020 and r = 0.64, p = 0.004) as well as CSAC exhalation and CSACR exhalation. CONCLUSION: In patients with insufficient exhalation, right MPAD during exhalation was decreased. Also, in COPD patients with insufficient exhalation, right MPAD was reduced during inhalation as well as exhalation, which implied that exhalation impairment is a contributing factor to pulmonary hypertension complicated with COPD. RELEVANCE STATEMENT: Assessment of MPAD in different respiratory phases on DVCT has the potential to be utilized as a non-invasive assessment for pulmonary hypertension due to lung disease and/or hypoxia and elucidation of its pathogenesis. KEY POINTS: • There are no previous studies analyzing all respiratory phases of right main pulmonary artery distensibility (MPAD). • Patients with exhalation impairment decreased their right MPAD. • Analysis of MPAD on dynamic ventilation computed tomography contributes to understanding the pathogenesis of pulmonary hypertension due to lung disease and/or hypoxia in patients with expiratory impairment.

Applicability Evaluation of Full-Reference Image Quality Assessment Methods for Computed Tomography Images.

Image quality assessments (IQA) are an important task for providing appropriate medical care. Full-reference IQA (FR-IQA) methods, such as peak signal-to-noise ratio (PSNR) and structural similarity (SSIM), are often used to evaluate imaging conditions, reconstruction conditions, and image processing algorithms, including noise reduction and super-resolution technology. However, these IQA methods may be inapplicable for medical images because they were designed for natural images. Therefore, this study aimed to investigate the correlation between objective assessment by some FR-IQA methods and human subjective assessment for computed tomography (CT) images. For evaluation, 210 distorted images were created from six original images using two types of degradation: noise and blur. We employed nine widely used FR-IQA methods for natural images: PSNR, SSIM, feature similarity (FSIM), information fidelity criterion (IFC), visual information fidelity (VIF), noise quality measure (NQM), visual signal-to-noise ratio (VSNR), multi-scale SSIM (MSSSIM), and information content-weighted SSIM (IWSSIM). Six observers performed subjective assessments using the double stimulus continuous quality scale (DSCQS) method. The performance of IQA methods was quantified using Pearson's linear correlation coefficient (PLCC), Spearman rank order correlation coefficient (SROCC), and root-mean-square error (RMSE). Nine FR-IQA methods developed for natural images were all strongly correlated with the subjective assessment (PLCC and SROCC > 0.8), indicating that these methods can apply to CT images. Particularly, VIF had the best values for all three items, PLCC, SROCC, and RMSE. These results suggest that VIF provides the most accurate alternative measure to subjective assessments for CT images.

Usefulness of preset count acquisition in pediatric 99m Tc-DMSA planar imaging.

OBJECTIVE: This study was aimed at determining the minimum acquisition count to provide diagnosable image quality (DIQ) and investigating the usefulness of preset count acquisition (PCA) for planar images of pediatric 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy. METHODS: First, we calculated a coefficient of variation (CV) for DIQ with the shortest acquisition time through visual evaluation in 12 pediatric patients who underwent 99mTc-DMSA scintigraphy. Second, a minimum acquisition count to achieve the CV for DIQ was determined with the single regression analysis using CV as an explanatory variable and the total acquisition count as an objective variable in 81 pediatric patients. Finally, we compared PCA images based on the minimum acquisition count and preset time acquisition (PTA) images for 5 min in terms of the acquisition time, CV, and renal uptake ratio in another 23 pediatric patients. RESULTS: The visual evaluation showed that the CV corresponding to DIQ with the shortest acquisition time was 27.1%. The total acquisition count corresponding to DIQ was revealed to be 299,764 in the single regression analysis and was determined to be 300,000 after rounding. The CV and its standard deviation in PCA at 300,000 counts and PTA for 5 min were 26.4 ± 0.6% and 24.8 ± 1.3%, respectively. The standard deviation of CV in PCA at 300,000 counts was smaller than that in PTA for 5 min, indicating little variation in image quality between cases. The acquisition time in PCA at 300,000 counts (3.1 ± 0.7 min) was shorter than that in PTA for 5 min (5.0 ± 0.0 min). The intraclass correlation coefficient between renal uptake ratios for PCA and PTA was 0.98, indicating an extremely high concordance. CONCLUSIONS: The minimum acquisition count required for the DIQ was 300,000. In addition, PCA at 300,000 counts was demonstrated to be useful by providing stable image quality at the shortest acquisition time.

Association of Respiratory Functional Indices and Smoking with Pleural Movement and Mean Lung Density Assessed Using Four-Dimensional Dynamic-Ventilation Computed Tomography in Smokers and Patients with COPD.

Purpose: To correlate the ratio of the non-dependent to dependent aspects of the maximal pleural movement vector (MPMVND/D) and gravity-oriented collapse ratio (GCRND/D), and the mean lung field density (MLD) obtained using four-dimensional (4D) dynamic-ventilation computed tomography (DVCT) with airflow limitation parameters and the Brinkman index. Materials and Methods: Forty-seven patients, including 22 patients with COPD, 13 non-COPD smokers, and 12 non-smokers, with no/slight pleural adhesion confirmed using a thoracoscope, underwent 4D-DVCT with 16 cm coverage. Coordinates for the lung field center, as well as ventral and dorsal pleural points, set on the central trans-axial levels in the median and para-median sagittal planes at end-inspiration, were automatically measured (13-17 frame images, 0.35 seconds/frame). MPMVND/D and GCRND/D were calculated based on MPMV and GCR values for all the included points and the lung field center. MLD was automatically measured in each of the time frames, and the maximal change ratio of MLD (MLDCR) was calculated. These measured values were compared among COPD patients, non-COPD smokers, and non-smokers, and were correlated with the Brinkman index, FEV1/FVC, FEV1 predicted, RV/TLC, and FEF25-75% using Spearman's rank coefficients. Results: MPMVND/D was highest in non-smokers (0.819±0.464), followed by non-COPD smokers (0.405±0.131) and patients with COPD (-0.219±0.900). GCRND/D in non-smokers (1.003±1.384) was higher than that in patients with COPD (-0.164±1.199). MLDCR in non-COPD smokers (0.105±0.028) was higher than that in patients with COPD (0.078±0.027). MPMVND/D showed positive correlations with FEV1 predicted (r=0.397, p=0.006), FEV1/FVC (r=0.501, p<0.001), and FEF25-75% (r=0.368, p=0.012). GCRND/D also demonstrated positive correlations with FEV1 (r=0.397, p=0.006), FEV1/FVC (r=0.445, p=0.002), and FEF25-75% (r=0.371, p=0.011). MPMVND/D showed a negative correlation with the Brinkman index (r=-0.398, p=0.006). Conclusion: We demonstrated that reduced MPMVND/D and GCRND/D were associated with respiratory functional indices, in addition to a negative association of MPMVND/D with the Brinkman index, which should be recognized when assessing local pleural adhesion on DVCT, especially for ventral pleural aspects.

Immune-related aseptic meningitis diagnosed by Cube FLAIR on enhanced magnetic resonance imaging for a lung cancer patient administered atezolizumab: A case report.

Immune checkpoint inhibitors (ICIs) can cause immune-related adverse events (irAEs), such as neurological toxicity. A 46-year-old man was diagnosed with squamous cell lung cancer. Lung cancer recurred 3 years after he experienced left segmental lung rejection. Therefore, he received atezolizumab as fourth-line chemotherapy. He experienced fever, headache, and decreased consciousness 10 days after the first dose of atezolizumab. Plain head computed tomography and cerebrospinal fluid examination showed no significant findings. Magnetic resonance imaging (MRI) with a Gadolinium (Gd)-enhanced Cube fluid-attenuated inversion recovery (FLAIR) sequence showed nodular abnormalities with contrast enhancement. Thus, aseptic meningitis caused by ICIs was suspected. His consciousness level gradually improved with glucocorticoid therapy. Moreover, most nodular abnormalities observed on cerebral MRI disappeared concurrently. Thus, Gd-enhanced Cube FLAIR sequence has the unique ability to reveal immune-related aseptic meningitis.

Computed tomography imaging findings of nivolumab-induced thyroid dysfunction.

The thyroid gland is most frequently involved in immune-related adverse events (irAEs) by nivolumab. We reviewed the thyroid function and thyroid gland volume and volume change ratio between baseline and follow-up CT (volume follow-up/volume baseline) in 24 patients treated with nivolumab for lung cancer and renal cell carcinoma. Among them, four (16.7%) demonstrated nivolumab-induced thyroid dysfunction that shows either hypothyroidism or hyperthyroidism. Three and one cases were treated with nivolumab for lung cancer and renal cell carcinoma, respectively. Two patients with hypothyroidism (cases 1 and 2) showed reduced thyroid volume (volume change ratio: 0.80 and 0.84) on computed tomography (CT) images. Besides, remarkably diminished CT attenuation of the thyroid gland was observed in a patient with hypothyroidism (case 2). One of the two patients with hyperthyroidism showed increased thyroid volume (volume change ratio: 1.32) (case 3), whereas no difference in the thyroid gland volume was observed between the previous and follow-up CT in another patient with hyperthyroidism (case 4). Thyroid volume change ratio >0.1 was observed even in 6 of 20 (30%) patients without thyroid dysfunction. Considering the wide use of nivolumab in cancer treatment, radiologists should be aware that changes in the thyroid volume and attenuation on CT are associated with thyroid dysfunction caused by nivolumab, as well as thyroid volume may change even in patients with normal thyroid function during nivolumab therapy.

Ex-vivo aortic root and coronary artery cast measurement to validate the accuracy of virtual imaging.

BACKGROUND AND AIM OF THE STUDY: To investigate the accuracy of two methods of measuring features in cardiac anatomy, using an objective standard cast model. METHODS: We made a silicone cast using a swine heart. Computerized tomography data of the solidified cast were processed through virtual reality (VR) software and through two-dimensional multiplanar-reconstruction (2D-MPR), and all measurements were compared against physical measurements of the cast. RESULTS: The cast perfectly demonstrated the fine detail of the aortic valve and the proximal parts of coronary arteries. Anatomical features were measured by 3D-VR, 2D-MPR, and directly on the cast. Measurement differences between 2D-MPR and the cast were on average at least 3.6 times larger than those between 3D-VR and the cast. CONCLUSIONS: Based on the observed accuracy, 3D-VR measurements seem considerably more accurate than the current standard 2D-MPR, and 3D-VR may be considered as the next gold standard for 3D measurement of cardiac anatomy in vivo.

Risk factors for pneumonitis in advanced extrapulmonary cancer patients treated with immune checkpoint inhibitors.

BACKGROUND: Immune-mediated pneumonitis has a high mortality rate; however, information regarding the related risk factors remains limited. This study aimed to analyze risk factors for pneumonitis, including smoking and lung metastasis (LM), in patients with extrapulmonary primary tumors. METHODS: Data of 110 patients treated with immune checkpoint inhibitors (ICIs) (nivolumab/pembrolizumab) for treating extrapulmonary primary tumors at the Shiga University of Medical Science Hospital between January 2015 and December 2019 were retrospectively collected. The association between the onset of pneumonitis and treatment-related factors was analyzed by logistic regression. The severity of pneumonitis was graded according to the Common Terminology Criteria for Adverse Events version 5.0. Risk factors, such as the absence or presence of interstitial lung disease (ILD) and LM, or other clinical factors, including smoking status before ICI administration, were analyzed. RESULTS: Multivariate analyses indicated that the amount of smoking was significantly associated with an increase in the development of all-grade pneumonitis types (odds ratio (OR) = 20.33, 95% confidence interval (CI) = 20.03-20.66; p = 0.029). LM and ILD were significantly related to an increase in the development of symptomatic pneumonitis (≥ Grade 2) (OR = 10.08, 95% CI = 1.69-199.81; p = 0.076, and OR = 6.76, 95% CI = 1.13-40.63; p = 0.037, respectively). CONCLUSIONS: Pre-screening for ILD and LM and recognizing patients' smoking history is important for determining the risk of ICI-induced pneumonitis and allowing safe ICI administration.

[A Novel Virtual-reality Imaging System in Cardiovascular Surgery:a Potentially Promising Technology for Surgeons].

Adequate preoperative planning may facilitate successful procedures in cardiovascular surgery. We have developed a system named the Vesalius 3D suite, combining three-dimensional (3D) image-processing software with an optic-tracking spatial navigation, allowing quick, accessible 3D image interpretation for virtual reality (VR) exploration and measurement from one or more of a range of imaging modalities. We present a novel method of virtual imaging analysis for preoperative planning and simulation in cardiovascular surgery using this 3D-VR system. Based on unimodal or multimodal medical imaging data, digital imaging and communication in medicine (DICOM) data sets can be reconstructed for 3D visualization. Virtually reconstructed images can be viewed on flat-screen or stereoscopic display, revealing each patient's specific anatomy and the internal structures in exquisite detail. Highly accessible 3D interpretation promptly permits precise measurements of repair-relevant anatomical parameters including geometrically complex shapes. This technology may promote understanding of form and function in the cardiovascular system, and facilitate operative procedures in more challenging cases, and it seems especially valuable for any surgeon to gain experience in practicing for rarely-performed procedures or uncommon patient-specific preoperative surgical rehearsal.

Validation of Virtual Imaging of a Dynamic, Functioning Aortic Valve Using an Ex Vivo Porcine Heart.

PURPOSE: To investigate a virtual reality imaging system in terms of visualization accuracy and appropriate orientation when displaying cardiac anatomy, we used an ex vivo model enabling direct comparison between reconstructed 3-dimensional visualization of intracardiac structures and real-time visual images. DESCRIPTION: We established a systole-diastole platform using a swine heart activated by an external mechanical pump and reservoir, allowing simultaneous acquisition of endoscopic visual and computed tomography images of the aortic valve. Virtual images were processed from computed tomography data using 3-dimensional software (the Vesalius 3D suite; PS Medtech, Amsterdam, Netherlands) and compared with visual images seen through a fiberoptic scope. EVALUATION: An endoscope gave a fine view of the aortic valve, whereas the virtual images elucidated the valve structures. Superimposition of the images from the 2 different modalities showed the virtual reality images precisely matching the visual images in both systole and diastole, confirming the validity of this virtual reality application. CONCLUSION: In view of this demonstrated fidelity of virtual imaging, this technology may be of sufficiently high quality to be considered a gold standard for cardiac anatomy.

Detailed short-term follow-up high-resolution CT series of differentiation syndrome.

A 57-year-old man with acute promyelocytic leukaemia (APML) received induction therapy including all-trans-retinoic acid (ATRA). At day 15, he developed dyspnoea, haemoptysis and hypoxia. Thorax CT demonstrated diffuse ground-glass opacity and consolidation predominantly in dorsal regions, which may reflect increased vascular permeability. He was diagnosed with differentiation syndrome. After dexamethasone was administered and chemotherapy suspended, his symptoms improved and abnormal lesions mostly disappeared on follow-up CT examinations. We report a short-term high-resolution CT series of differentiation syndrome.

A novel strategy to develop deep learning for image super-resolution using original ultra-high-resolution computed tomography images of lung as training dataset.

PURPOSE: To improve the image quality of inflated fixed cadaveric human lungs by utilizing ultra-high-resolution computed tomography (U-HRCT) as a training dataset for super-resolution processing using deep learning (SR-DL). MATERIALS AND METHODS: Image data of nine cadaveric human lungs were acquired using U-HRCT. Three different matrix images of U-HRCT images were obtained with two acquisition modes: normal mode (512-matrix image) and super-high-resolution mode (1024- and 2048-matrix image). SR-DL used 512- and 1024-matrix images as training data for deep learning. The virtual 2048-matrix images were acquired by applying SR-DL to the 1024-matrix images. Three independent observers scored normal anatomical structures and abnormal computed tomography (CT) findings of both types of 2048-matrix images on a 3-point scale compared to 1024-matrix images. The image noise values were quantitatively calculated. Moreover, the edge rise distance (ERD) and edge rise slope (ERS) were also calculated using the CT attenuation profile to evaluate margin sharpness. RESULTS: The virtual 2048-matrix images significantly improved visualization of normal anatomical structures and abnormal CT findings, except for consolidation and nodules, compared with the conventional 2048-matrix images (p < 0.01). Quantitative noise values were significantly lower in the virtual 2048-matrix images than in the conventional 2048-matrix images (p < 0.001). ERD was significantly shorter in the virtual 2048-matrix images than in the conventional 2048-matrix images (p < 0.01). ERS was significantly higher in the virtual 2048-matrix images than in the conventional 2048-matrix images (p < 0.01). CONCLUSION: SR-DL using original U-HRCT images as a training dataset might be a promising tool for image enhancement in terms of margin sharpness and image noise reduction. By applying trained SR-DL to U-HRCT SHR mode images, virtual ultra-high-resolution images were obtained which surpassed the image quality of unmodified SHR mode images.

18F-fluorodeoxyglucose uptake in advanced gastric cancer correlates with histopathological subtypes and volume of tumor stroma.

PURPOSE: The aim of this study was to investigate the correlation between preoperative 18F-fluorodeoxyglucose (FDG) uptake and histological subtypes, amount of tumor stroma in advanced gastric cancer (GC), and clinical outcomes. METHODS: We evaluated 56 patients (male/female, 42:14; mean age, 69 years) with advanced GC who underwent surgical resection at our institution and positron emission tomography-computed tomography with 18F-FDG prior to surgery. We used the maximum standardized uptake value (SUVmax) of the tumor and the tumor-to-liver ratio (TLR) of the SUVmax for the analysis. The SUVmax and TLR correlated with histological subtypes, immunohistochemistry (IHC) for CD34, and recurrence-free survival (RFS). Tumor stroma in GC was evaluated by CD34 expression. GCs were classified according to the Lauren and World Health Organization (WHO) classifications. RESULTS: The average FDG uptakes (SUVmax) were 4.17% and 14.04% in diffuse and intestinal type GCs, respectively, according to the Lauren classification, and 4.17%, 13.87%, 7.70%, 9.71%, and 19.45% in the poorly cohesive, tubular, mucinous, and papillary adenocarcinomas, respectively, according to the WHO classification. The FDG uptake in diffuse type was significantly lower than that in the intestinal type (p = 0.000). The SUVmax and TLR of the CD34(+) group (mean SUVmax, 5.50; TLR, 1.56) were significantly lower than those of the CD34(-) group (mean SUVmax, 14.09; TLR, 4.09). RFS was not associated with TLR or CD34 expression. CONCLUSION: GC, which has abundant tumor stroma characterized by high CD34 expression on IHC, shows low FDG uptake.

A Virtual-Reality Imaging Analysis of the Dynamic Aortic Root Anatomy.

PURPOSE: To measure and explore complex cardiac anatomy in research and preoperative simulation, a virtual imaging technology-the Vesalius 3D suite (PS Medtech, Amsterdam, Netherlands)-combines Vesalius three-dimensional (3D) image-processing software with an optic-tracking navigation system running PST-Client software. We present a novel method of evaluating dynamic aortic root geometry in vivo using this visualization system. DESCRIPTION: Based on electrocardiography-gated cardiac computed tomography data in systole and diastole, images of the aortic root in a healthy adult were reconstructed for 3D visualization. Virtual interaction tools were used to explore and measure the aortic root structures. EVALUATION: Virtually reconstructed images revealed the aortic root internal structures in exquisite detail. Highly accessible 3D interpretation promptly permitted precise measurements of repair-relevant anatomic parameters, including geometrically complex curves of the aortic root wall and dynamic changes in the aortic valves. Measurement accuracy examined against a known prosthesis showed within 1 mm of error (less than 0.5%). CONCLUSIONS: This technology may promote understanding of aortic root form and function, and facilitate valve-sparing surgery, and seems valuable for 3D exploration and measurement of cardiac anatomy in vivo.

Effective Control of Brain Metastases Irrespective of Distance from Isocenter in Single-isocenter Multitarget Stereotactic Radiosurgery.

BACKGROUND/AIM: Few previous studies have evaluated the effectiveness of single-isocenter multitarget (SIMT) stereotactic radiosurgery (SRS) in clinical practice. PATIENTS AND METHODS: Gross tumor volumes of 113 metastases in 13 patients were measured by contrast-enhanced magnetic resonance imaging. Prescribed doses were set at 20-24 Gy. Based on tumor reduction rates (TRRs) measured before and after SIMT SRS, tumor shrinkage effect was categorized into four grades; almost disappeared: TRR=1, decreased: 0.3≤TRR<1, stable: -0.2

Increased 18F-FDG accumulation in less-affected lung area in patients with non-small cell lung cancer and postoperative acute exacerbation of interstitial lung disease.

PURPOSE: To investigate whether or not 18F-FDG accumulation in normal or less-affected lung fields increased in non-small cell lung cancer (NSCLC) patients with postoperative acute exacerbation (PAE) of interstitial lung disease (ILD) MATERIAL AND METHODS: Thirty-six NSCLC patients with ILD and 50 patients without ILD (non-ILD patients) underwent pre-operative 18F-FDG-PET/CT at 2 institutions. Volume-of-interest (VOI) was placed to measure the mean standardized uptake value (SUVmean) in normal or less-affected lung fields at pre-defined 12 areas on ventral and dorsal locations of both lungs. SUVtissue fraction (TF) was defined as corrected SUVmean by using TF and mean computed tomography density on PET/CT. Harmonized SUVmean (hSUVmean) and SUVTF (hSUVTF) were calculated based on results of phantom study, which was performed to optimize the measured SUV difference among 2 institutions. Both the h-SUVmean and the h-SUVTF were compared between 8 patients with PAE of ILD (PAE group) or remaining 28 patients without PAE of ILD (non-PAE group) and non-ILD patients in each of the 12 areas. RESULTS: The hSUVmean in PAE group was higher in 9 out of 12 locations as compared with non-ILD patients, whereas the hSUVmean was mostly similar between non-PAE group and non-ILD patients. In contrast, the hSUVTF in non-PAE group was similar to that in PAE group, and higher than in non-ILD patients in most locations. CONCLUSION: 18F-FDG-PET/CT demonstrated increased SUVmean along with elevated SUVTF in normal or less-affected lung fields for NSCLC patients with PAE of ILD, which may reflect regional invisible fibrosis and inflammatory change.

Usability of the lateral decubitus position on four-dimensional ultra-low-dose computed tomography for the detection of localized pleural adhesion in the pulmonary apical region.

BACKGROUND: Localized pleural adhesion (LPA) evaluation in the apical region is difficult even with four-dimensional ultra-low-dose computed tomography (4D-ULDCT) in the supine position due to smaller pleural movements. PURPOSE: To assess usability of 4D-ULDCT in the lateral decubitus (LD) position for LPA detection in the apical region. MATERIAL AND METHODS: Forty-seven patients underwent 4D-ULDCT of a single respiration cycle with 16-cm coverage of body axis in supine and LD positions with the affected lung uppermost. Intraoperative thoracoscopic findings confirmed LPA presence. A pleural point and a corresponding point on costal outer edge were placed in identical axial planes at end-inspiration. Pleuro-chest wall distance between two points (PCD) was calculated at each respiratory phase. In the affected lung, average change in amount of PCD (PCDACA) was compared between patients with and without LPA in total and two sub-groups (non-COPD and COPD, non-emphysematous and emphysematous patients) in supine and non-dependent (ND) LD positions. Receiver operating characteristic (ROC) curve analysis was performed to determine optimal thresholds in PCDACA for differentiating patients with LPA from those without. RESULTS: In COPD/emphysematous patients and total population, PCDACA with LPA was smaller than in those without in the supine and NDLD positions for overall, lateral, and dorsal regions. For the lateral region in COPD patients, area under ROC curve (AUC) increased from supine (0.64) to NDLD position (0.81). For the dorsal region in emphysematous patients, AUC increased from supine (0.76) to NDLD position (0.96). CONCLUSION: 4D-ULDCT in LD position may be useful for LPA detection in apical regions for COPD and/or emphysematous patients.

Preoperative assessment of localized pleural adhesion: Utility of software-assisted analysis on dynamic-ventilation computed tomography.

PURPOSE: To assess the usefulness of software analysis using dynamic-ventilation CT for localized pleural adhesion (LPA). MATERIALS AND METHODS: Fifty-one patients scheduled to undergo surgery underwent both dynamic-ventilation CT and static chest CT as preoperative assessments. Five observers independently evaluated the presence and severity of LPA on a three-point scale (non, mild, and severe LPA) for 9 pleural regions (upper, middle, and lower pleural aspects on ventral, lateral, and dorsal areas) on the chest CT by three different methods by observing images from: static high-resolution CT (static image); dynamic-ventilation CT (movie image), and dynamic-ventilation CT while referring to the adhesion map (movie image with color map), which was created using research software to visualize movement differences between the lung surface and chest wall. The presence and severity of LPA was confirmed by intraoperative thoracoscopic findings. Parameters of diagnostic accuracy for LPA presence and severity were assessed among the three methods using Wilcoxon signed rank test in total and for each of the three pleural aspects. RESULTS: Mild and severe LPA were confirmed in 14 and 8 patients. Movie image with color map had higher sensitivity (56.9 ±â€¯10.7 %) and negative predictive value (NPV) (91.4 ±â€¯1.7 %) in LPA detection than both movie image and static image. Additionally, for severe LPA, detection sensitivity was the highest with movie image with color map (82.5 ±â€¯6.1 %), followed by movie image (58.8 ±â€¯17.0 %) and static image (38.8 ±â€¯13.9 %). For LPA severity, movie image with color map was similar to movie image and superior to static image in accuracy as well as underestimation and overestimation, with a mean value of 80.2 %. CONCLUSION: Software-assisted dynamic-ventilation CT may be a useful novel imaging approach to improve the detection performance of LPA.

Peripheral bronchial luminal conspicuity on dynamic-ventilation computed tomography: association with radiation doses and temporal resolution by using an ex vivo porcine lung phantom.

BACKGROUND: It is still unclear which image reconstruction algorithm is appropriate for peripheral bronchial luminal conspicuity (PBLC) on dynamic-ventilation computed tomography (DVCT). PURPOSE: To assess the influence of radiation doses and temporal resolution (TR) on the association between movement velocity (MV) and PBLC on DVCT. MATERIAL AND METHODS: An ex vivo porcine lung phantom with simulated respiratory movement was scanned by 320-row CT at 240 mA and 10 mA. Peak and dip CT density and luminal area adjusted by values at end-inspiration (CTDpeak and CTDdip, luminal area ratio [LAR]) for PBLC and MVs were measured and visual scores (VS) were obtained at 12 measurement points on 13 frame images obtained at half and full reconstructions (TR 340 and 190 ms) during expiration. Size-specific dose estimate (SSDE) was applied to presume radiation dose. VS, CTDpeak, CTDdip, LAR, and their cross-correlation coefficients with MV (CCC) were compared among four methods with combinations of two reconstruction algorithms and two doses. RESULTS: The dose at 10 mA was presumed as 26 mA by SSDE for standard proportion adults. VS, CTDdip, CTDpeak, and LAR with half reconstruction at 10 mA (2.52 ± 0.59, 1.016 ± 0.221, 0.948 ± 0.103, and 0.990 ± 0.527) were similar to those at 240 mA except for VS, and different from those with full reconstruction at both doses (2.24 ± 0.85, 0.830 ± 0.209, 0.986 ± 0.065, and 1.012 ± 0.438 at 240 mA) (P < 0.05). CCC for CTDdip with half reconstruction (-0.024 ± 0.552) at 10 mA was higher compared with full reconstruction (-0.503 ± 0.291) (P < 0.05). CONCLUSION: PBLC with half reconstruction at 10 mA was comparable to that at 240 mA and better than those with full reconstruction on DVCT.

Preoperative assessment of parietal pleural invasion/adhesion of subpleural lung cancer: advantage of software-assisted analysis of 4-dimensional dynamic-ventilation computed tomography.

OBJECTIVE: To evaluate the accuracy of four-dimensional (4D) dynamic-ventilation computed tomography (CT) scanning coupled with our novel image analysis software to diagnose parietal pleural invasion/adhesion of peripheral (subpleural) lung cancer. METHODS: Eighteen patients with subpleural lung cancer underwent both 4D dynamic-ventilation CT during free breathing and conventional (static) chest CT during preoperative assessment. The absence of parietal pleural invasion/adhesion was surgically confirmed in 13 patients, while the presence of parietal pleural invasion/adhesion was confirmed in 5 patients. Two chest radiologists, who were blinded to patient status, cooperatively evaluated the presence of pleural invasion/adhesion using two different imaging modalities: (i) conventional high-resolution CT images, reconstructed in the axial, coronal, and sagittal directions, and (ii) 4D dynamic-ventilation CT images combined with a color map created by image analysis software to visualize movement differences between the lung surface and chest wall. Parameters of diagnostic accuracy were assessed, including a receiver operating characteristic analysis. RESULTS: Software-assisted 4D dynamic-ventilation CT images achieved perfect diagnostic accuracy for pleural invasion/adhesion (sensitivity, 100%; specificity, 100%; area under the curve [AUC], 1.000) compared to conventional chest CT (sensitivity, 60%; specificity, 77%; AUC, 0.846). CONCLUSION: Software-assisted 4D dynamic-ventilation CT can be considered as a novel imaging approach for accurate preoperative analysis of pleural invasion/adhesion of peripheral lung cancer. KEY POINTS: • 4D dynamic-ventilation CT can correctly assess parietal pleural invasion/adhesion of peripheral lung cancer. • A unique color map clearly demonstrates parietal pleural invasion/adhesion. • Our technique can be expanded to diagnose "benign" pleural adhesions for safer thoracoscopic surgery.