Evaluation of postoperative lung volume and perfusion changes by dual-energy computed tomography in patients with lung cancer

PurposeThe aim of our study was to retrospectively evaluate postoperative physiologic changes in lung cancer patients using dual-energy CT (DECT), and develop modified methods reflecting postoperative change for predicting pulmonary function.Methods and materials88 patients (M:F = 64:24; mean age, 63.5 years) with lung cancer who underwent DECT and pulmonary function tests before and after operation were included. Volume and iodine values for perfusion of each lobe were quantified. The predicted postoperative FEV1 using the current method was calculated by multiplying the preoperative FEV1 by the fractional contribution of perfusion of the remaining lung. The modified method reflecting postoperative volume change was compared to the current method.ResultsPostoperative lung volume showed compensatory increases in the contralateral and remaining ipsilateral lobes, with a significantly greater increase in the ipsilateral lobe than contralateral lobe (21.8% ± 46.2% vs. 10.0% ± 20.8%, P = 0.031). Perfusion analysis showed blood volume increases in both ipsilateral and contralateral lobes without statistical differences (blood volume ratio difference, 29.2% ± 26.7 vs. 24.6% ± 16.5, P = 0.368). The performance of the modified method considering postoperative lung volume change was comparable to that of the current method in the development and validation datasets (95% CI, −24.5% to 37.1% vs. −33.3% to 22.2% and −23.6% to 32.0% vs. −31.9% to 16.0%, respectively).ConclusionsPostoperative compensatory increases in lung volume and perfusion occur in different ways. Our modified method incorporating postoperative lung volume changes can be considered a comparable method for prediction of postoperative lung function.     

The safety of dipyridamole in patients undergoing myocardial perfusion scintigraphy prior to lung volume reduction surgery

Patients with end-stage chronic obstructive pulmonary disease (COPD) undergoing lung volume reduction surgery (LVRS) are at high risk of peri-operative cardiac complications, and myocardial perfusion scintigraphy (MPS) is commonly used for risk stratification. This study prospectively assessed the safety of dipyridamole in these patients and compared the incidence of side-effects (particularly dyspnoea) with that in patients undergoing dipyridamole MPS prior to elective non-cardiothoracic surgery. Fifty patients were enrolled: 25 in the LVRS cohort (13 males, 12 females), with a mean age of 65 years and a mean FEV₁ of 0.79 l, and 25 (with no history of asthma or COPD) in the control cohort (14 males, 11 females), with a mean age of 66 years. Fourteen patients (56%) in each group developed side-effects. Dyspnoea was reported by five patients (20%) in the LVRS and two patients (8%) in the control cohort (P=NS). One patient in each cohort developed severe hypotension and bradycardia. Eight (32%) other patients developed minor side-effects in the LVRS cohort compared with 11 (44%) in the control group. All side-effects responded promptly to intravenous aminophylline. In summary, there was a statistically non-significant increase in the incidence of dyspnoea in patients with end-stage COPD and all side-effects responded to aminophylline. Thus, dipyridamole can be used safely in these patients.     

The safety of dipyridamole in patients undergoing myocardial perfusion scintigraphy prior to lung volume reduction surgery

Patients with end-stage chronic obstructive pulmonary disease (COPD) undergoing lung volume reduction surgery (LVRS) are at high risk of peri-operative cardiac complications, and myocardial perfusion scintigraphy (MPS) is commonly used for risk stratification. This study prospectively assessed the safety of dipyridamole in these patients and compared the incidence of side-effects (particularly dyspnoea) with that in patients undergoing dipyridamole MPS prior to elective non-cardiothoracic surgery. Fifty patients were enrolled: 25 in the LVRS cohort (13 males, 12 females), with a mean age of 65 years and a mean FEV1 of 0.791, and 25 (with no history of asthma or COPD) in the control cohort (14 males, 11 females), with a mean age of 66 years. Fourteen patients (56%) in each group developed side-effects. Dyspnoea was reported by five patients (20%) in the LVRS and two patients (8%) in the control cohort (P=NS). One patient in each cohort developed severe hypotension and bradycardia. Eight (32%) other patients developed minor side-effects in the LVRS cohort compared with 11 (44%) in the control group. All side-effects responded promptly to intravenous aminophylline. In summary, there was a statistically non-significant increase in the incidence of dyspnoea in patients with end-stage COPD and all side-effects responded to aminophylline. Thus, dipyridamole can be used safely in these patients.     

Computerized estimation of the lung volume removed during lung volume reduction surgery

RATIONALE AND OBJECTIVES: This study was designed to develop an automated method for estimating lung volume removed during lung volume reduction surgery (LVRS) using computed tomography (CT). MATERIALS AND METHODS: The CT examinations of six patients who underwent bilateral LVRS were analyzed in this study. The resected lung tissue (right and left) was weighed during pathologic examination. An automated computer scheme was developed to estimate the lung volume removed using the CT voxel values and lung specimen weight. The computed fraction of lung volume removed was evaluated across a range of simulated surgical planes (ie, other than parallel to the CT image plane) and CT reconstruction kernels, and it was compared with the surgeons' postsurgical estimates. RESULTS: The computed fraction of the lung volume removed during LVRS was linearly correlated with the resected lung tissue weight (Pearson correlation = 0.697, P = .012). The computed fraction of lung volume removed ranged from 12.9% to 51.7% of the total lung volume. The surgeons' postsurgical estimates of lung volume removed ranged from 30% to 33%. The percent difference between the surgeons' estimates and the computed lung volume removed as a percentage of the surgeons' estimates ranged from -72.3% to 57.0% with mean absolute difference of 29.7% (+/-20.7). CONCLUSION: The preliminary findings of this study suggest that the proposed quantitative model should provide an objective measure of lung volume removed during LVRS that may be used to investigate the relationship between lung volume removed and outcome.     

3D computerized segmentation of lung volume with computed tomography

Three-dimensional (3D)-based detection and diagnosis has an important role for significantly improving the detection and diagnosis of lung cancer upon computed tomography (CT). This report presents a 3D-based method for segmenting and visualizing lung volume by using CT images. An anisotropic filtering method was developed on CT slices to enhance the signal-to-noise ratio, and a wavelet transform-based interpolation method was used combined with volume rendering to construct the 3D volumetric data based on entire CT slices. Then an adaptive 3D region-growing algorithm was designed to segment lung volume, incorporated by automatic seed-locating methods through fuzzy logic algorithms and 3D morphological closing approaches. In addition, a 3D visualization tool was designed to view volumetric data, projections, or intersections of the lung volume at any view angle. This segmentation method was tested on single-detector CT images by percentage of volume overlap and percentage of volume difference. The experiment results show that the developed 3D-based segmentation method is effective and robust. This study lays the groundwork for 3D-based computerized detection and diagnosis of lung cancer with CT imaging. In addition, this approach can be integrated into a picture archiving and communication system serving as a visualization tool for radiologists' reading and interpretation.     

Evaluation of the mediastinal-thoracic volume ratio on postmortem computed tomography

International Journal of Legal Medicine - The aim of this study was to measure the mediastinal-thoracic volume ratio (CTR_VOL) on PMCT as a more accurate version of traditional CTR, in order to...     

Imaging of patients with severe emphysema considered for lung volume reduction surgery.

Lung volume reduction surgery has recently been reintroduced as a palliative treatment for patients with severe emphysema. Selection criteria vary between centres and imaging is extensively used, but the exact role of individual techniques in the selection process is still emerging.     

Preoperative risk stratification by adenosine thallium 201 single-photon emission computed tomography in patients undergoing vascular surgery

Background

Adenosine perfusion scintigraphy is a powerful technique for diagnosing coronary artery disease and risk stratifying patients with recent myocardial infarction.

Methods and Results

We investigated the use of adenosine ²⁰¹Tl tomography to risk stratify 106 patients undergoing vascular arterial reconstruction consisting of lower limb arterial grafting in 44, aortic aneurysmectomy in 36, and carotid endarterectomy in 26 patients. Abnormal tomograms occurred in 57 patients (54%), 47 (82%) of whom had reversible perfusion defects. There were three postoperative deaths, all in the group that underwent aortic aneurysmectomy. Another patient with an aortic aneurysm had unstable angina and one patient who underwent lower limb arterial surgery had pulmonary edema after surgery. No patient without transient defects had an event (negative predictive value 100%). Cardiac events occurred only in patients with transient perfusion defects. However, only 5 of 47 such patients had events (positive predictive value 11%). The perfusion defect size (23%±14% vs 8.9%±135; p=0.034) and the ischemic fraction (20%±16% vs 5.6%±8.9%; p=0.009) were 2.5- and 3.5-fold larger, respectively, in patients with than in those without events. A history of diabetes mellius or previous infarction did not enhance the predictive value of the test.

Conclusion

Thus absence of reversible hypoperfusion during adenosine scintigraphy ensures virtual absence of postoperative cardiac events. Patients undergoing aortic aneurysmectomy may be targeted preferentially for risk-stratification strategies in the future.     

Lung perfusion scintigraphy prior to lung volume reduction surgery

PURPOSE: The aim of this study was to evaluate whether lung perfusion scintigraphy (LPS) contributes to the preoperative classification of emphysema heterogeneity in patients undergoing LVRS (lung volume reduction surgery) compared to classification based only on computed tomography (CT). MATERIAL AND METHODS: Forty-five potential candidates for LVRS were examined with CT and LPS. The distribution of emphysema within the lungs was visually classified into three categories: markedly heterogeneous, intermediately heterogeneous, or homogeneous. The results of the two imaging techniques were compared to an objective, CT-based computerized classification of heterogeneity. RESULTS: Visual evaluation of all 90 lungs resulted in 50 correct classifications based on CT, in 40 based on LPS and in 68 correct classifications based on the combination of CT and LPS. The combination was superior to CT alone (p<0.01) in classification of emphysema heterogeneity. There was no significant difference between the evaluations based on either CT or LPS. CONCLUSION: The combined information from CT and LPS are superior in assessing emphysema heterogeneity prior to LVRS.     

Left ventricular volume determination from single-photon emission computed tomography

To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterization for coronary artery or valvular heart disease were first evaluated scintigraphically. A simple, count-corrected voxel counting technique was used to derive left ventricular end-diastolic volume from transaxial SPECT slices. SPECT volume values showed a high degree of correlation with those determined by angiography (r = 0.969), with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting.     

Repeatability of quantitative CT indexes of emphysema in patients evaluated for lung volume reduction surgery

PURPOSE: To evaluate the repeatability of quantitative computed tomographic (CT) indexes of emphysema and the effect of spirometric gating of lung volume during CT in candidates for lung volume reduction surgery (LVRS). MATERIALS AND METHODS: Initial and same-day repeat routine inspiratory spiral chest CT studies were performed in 29 LVRS candidates (group 1, routine study vs repeat study). In a separate cohort of 29 LVRS candidates, spiral chest CT studies were performed both without and with spirometric gating by using a spirometer to trigger scanning at 90% of vital capacity (group 2, spirometric gating study). In each study, Pearson and intraclass correlation coefficients were calculated to determine the agreement between multiple pairs of whole-lung quantitative CT indexes of emphysema, and mean values were compared with two-tailed paired t tests. RESULTS: Pearson and intraclass correlation coefficients were high for all quantitative CT indexes (all > or = 0.92). No significant differences were found between mean values of quantitative CT indexes in group 1. Variation in quantitative CT results was small but more prominent in group 2 than in group 1. The variation in quantitative CT results was primarily related to differences in lung volume (r(2) as great as 0.83). CONCLUSION: Repeatability of quantitative CT test results in LVRS candidates is high and unlikely to improve by using spirometric gating.     

Measurement of lung gas volume and regional density by computed tomography in dogs

To determine if computed tomography (CT) can accurately measure lung volume, we compared lung gas volume measured by helium dilution with the equivalent volume calculated from CT total lung volume and density in 13 supine dogs. CT lung gas volume underestimated helium volume by 34% (range: -63 to 0%). Studies of wooden lung phantoms varying in density from 0.082g/cc to 0.776g/cc showed that only 15% of this error could be mimicked by the phantoms. The rest of the discrepancy is attributed to the lung's irregular borders, and the sharp density gradients surrounding and within the lung that result in x-ray beam hardening, sampling limitations, and partial volume measurement errors. Serial biweekly measurements in three dogs for 14 weeks showed CT gas volume to be highly reproducible with less scatter than seen in the helium measurements. Density in the lungs of all dogs showed a uniform gradual decrease from approximately 0.60g/cc at the dependent surface to 0.20g/cc at the superior surface with relatively constant density at any horizontal level. These studies show that whereas CT underestimates gas volume in the lungs, serial measurements are highly reproducible in experimental studies and are a promising technique to monitor diseases or response to therapy. Density gradients in the lungs were sufficiently uniform so that disruption of the normal gradient may be an indicator of early lung disease.     

Dynamic computed tomography of the neonatal lung: volume calculations and validation in an animal model

PURPOSE: The purpose of this study was to evaluate and validate dynamic volume calculation by respiratory-gated multislice computed tomography (CT) in small neonatal animals. MATERIALS AND METHODS: Six mechanically ventilated newborn piglets were imaged in a multislice CT with 0.5-mm slice thickness (4:16 pitch, 0.5-second rotation time, 120 kV). The respirator was connected to the CT unit for recording the respiratory signal. Simultaneously, tidal volume was measured by the respirator and functional residual capacity (FRC) using a multiple-breath washin-washout technique (MBW) with heptafluoropropane (HFP) as tracer gas. Complete volume datasets were reconstructed throughout the respiratory cycle in increments of 10% using retrospective half-scan gating. All animals were scanned in 3 different ventilator settings. Dynamic lung volumes (tidal volumes) were calculated by means of segmentation of the lung parenchyma during the respiratory cycle using work-in-progress software. RESULTS: The mean (+/-standard deviation) FRC determined by CT was 24.7+/-8.6 mL versus 24.8+/-7.3 mL for the MBW technique. There was no statistically significant difference (P=0.555). Pearson's correlation coefficient showed a strong correlation between the data obtained with CT and that obtained with the MBW technique (r=0.886). After exclusion of one outlier, tidal volumes showed a similar correlation (r=0.837) without significant differences in the mean values (CT: 8.9+/-2.4 mL and respirator: 8.7+/-2.4 mL, P=0.566). CONCLUSION: Dynamic multislice CT with respiratory gating allows for calculation of lung volumes and may be useful for future CT applications in human neonatal lung imaging.     

Preliminary application of dynamic pulmonary xenon-133 single-photon emission tomography in the evaluation of patients with pulmonary emphysema for thoracoscopic lung volume reduction surgery

Dynamic pulmonary xenon-133 single-photon emission tomography (SPET) with three-dimensional (3D) displays was preliminarily applied to select resection targets for thoracoscopic lung volume reduction surgery (LVRS) and to assess regional ventilatory changes following surgery. Dynamic SPET was performed using a triple-detector SPET system in 14 patients with pulmonary emphysema before and after LVRS. After reconstructing colour-illuminated, surface-rendered 3D images of equilibrium (EQ) and 3-min washout (WO₃), a single 3D fusion display was created from these two different time-course image sets, in which the 3D WO₃ image indicating ¹³³Xe retention was visible through the overlying 3D EQ image delineating lung contours. Volumetric extent of retention on this display was quantified by a ¹³³Xe retention index, defined as the ratio (%) of total pixel numbers of segmented 3-min WO data to those of EQ data. ¹³³Xe SPET and appropriately thresholded 3D displays efficiently localized a total of 36 retention sites; 19 (52.7%) of these sites were not localized by CT because they were within the widely or homogeneously spreading non-bullous emphysematous lung tissues. The 3D displays enhanced the perception of anatomical configurations and the extent of ¹³³Xe retention compared with multislice tomograms. Postoperatively, 3D fusion display visualized the details of regional changes in retention, and changes in the retention index on the 3D display with a standardized threshold correlated well with changes in ¹³³Xe clearance time (T _1/2) and %FEV₁ (r = 0.881 and 0.856, respectively; P<0.0001). This preliminary study indicates that ¹³³Xe SPET and appropriately thresholded, topographic 3D displays are of potential use in selecting resection targets for LVRS, and in evaluating the treatment effects on regional ventilation. Received 23 September and in revised form 11 November     

CT薄层扫描对于周围型小肺癌的诊断价值

目的 研究周围型小肺癌于CT薄层扫描的表现，并确定提示其诊断的某些继发征象之发生率。方法 48例可疑周围型小肺癌患均经CT薄层（2-3mm)扫描，并预期地分析了其CT征象。结果 48例周围型小肺癌中，细支气管肺泡癌24例，腺癌11例，鳞癌6例，小细胞癌5例，以及未发分化癌2例。周围型小肺癌的主要CT征象有：深分叶征见于43例（90%），边缘毛刺征36例（75%），空泡征27例（56%）。胸膜凹陷征38例（79%），以及血管集束征33例（69%）。结论 在周围型小肺癌诊断中，CT征象起着重要作用。尤其薄层扫描能够更加清晰地显示上述诸征象，因而能够提高小肺癌的确诊率。     

Urachal carcinoma: Evaluation with computed tomography

The computed tomographic (CT) findings in 7 patients with urachal carcinoma were reviewed. Computed tomography was useful in establishing an initial diagnosis, determining the tumor extent, and visualizing tumor recurrence. The embryology, histology, and clinical course of urachal carcinoma are reviewed.     

多层螺旋CT三维重组对肺减容术前的形态学评估

目的探讨多层螺旋CT（MSCT）容积再现技术（VRT）显示肺气肿组织最佳的重组阈值区间，及其作为肺减容术（LVRS）靶区（拟行切除的肺气肿组织）显示手段的价值。方法对56例拟行LVRS的肺气肿患者行呼气相肺部扫描，按照CT检查时间的先后将患者分为A组和B组。以-1024～-960HU、-1024～-910HU分别作为LVRS手术靶区的重组阈值区间，对A组的原始薄层图像行VRT重组，并将2种重组阈值的VRT图像分别与轴面图像、多平面重组（MPR）图像对比，确定显示LVRS靶区的最佳重组阈值区间。B组根据A组选定的重组阈值区间进行VRT重组，计数并对比VRT与二维图像中直径≥3cm的肺大泡在各肺叶的分布，应用配对t检验验证2种计数结果。结果A组中以-1024 — -960HU作为肺气肿重组阈值区间的VRT图像对LVRS手术靶区显示较佳，与相对正常肺组织对比较鲜明，病变的程度、范围与二维图像符合程度高。B组中VRT图像与原始图像分析结果一致，对肺大泡的定位及计数结果与原始图像基本一致，肺右上、右中、右下、左上、左下叶计数对比，二维图像分别显示：（4．22±2．09）、（4、44±2．59）、（2．18±0．92）、（3．54±2．03）和（4．40±2．42）个；VRT分别显示：（4．12±2．12）、（4．44±2．59）、（2．18±0．87）、（3．50±1．99）和（4．28±2．28）个（t值分别为1．98、0．00、1．77、1．76、1．81，P值均〉0．05）。结论以-1024～-960HU作为肺气肿组织的重组阈值，VRT成像可以准确显示肺气肿的分布类型，立体直观的显示LVRS手术靶区，为术前形态评估和术后效果预测提供了新方法。