Regional mapping of gas uptake by blood and tissue in the human lung using hyperpolarized xenon-129 MRI

PURPOSE

To develop a breathhold acquisition for regional mapping of ventilation and the fractions of hyperpolarized xenon-129 (Xe129) dissolved in tissue (lung parenchyma and plasma) and red blood cells (RBCs), and to perform an exploratory study to characterize data obtained in human subjects.

MATERIALS AND METHODS

A three-dimensional, multi-echo, radial-trajectory pulse sequence was developed to obtain ventilation (gaseous Xe129), tissue, and RBC images in healthy subjects, smokers, and asthmatics. Signal ratios (total dissolved Xe129 to gas, tissue-to-gas, RBC-to-gas, and RBC-to-tissue) were calculated from the images for quantitative comparison.

RESULTS

Healthy subjects demonstrated generally uniform values within coronal slices, and a gradient in values along the anterior-to-posterior direction. In contrast, images and associated ratio maps in smokers and asthmatics were generally heterogeneous and exhibited values mostly lower than those in healthy subjects. Whole-lung values of total dissolved Xe129 to gas, tissue-to-gas, and RBC-to-gas ratios in healthy subjects were significantly larger than those in diseased subjects.

CONCLUSION

Regional maps of tissue and RBC fractions of dissolved Xe129 were obtained from a short breathhold acquisition, well tolerated by healthy volunteers and subjects with obstructive lung disease. Marked differences were observed in spatial distributions and overall amounts of Xe129 dissolved in tissue and RBCs among healthy subjects, smokers and asthmatics.

Bronchioloalveolar carcinoma: focal area of ground-glass attenuation at thin-section CT as an early sign

PURPOSE

To assess an early thin-section computed tomographic (CT) finding of the localized formation of bronchioloalveolar carcinoma (BAC).

MATERIALS AND METHODS

From October 1994 to September 1995, four consecutive patients with biopsy-proved BAC were studied. Thin-section CT (n=4), radiographic (n=4), pathologic (n=4), and positron emission tomographic (n=2) findings were analyzed.

RESULTS

Chest radiographs showed focal areas of poorly defined nodules (n=2) and poorly defined opacity (n=2). At thin-section CT, lesions appeared as isolated areas of ground-glass attenuation (n=2) and mixed areas of ground-glass attenuation and consolidation (n=2). The areas of ground-glass attenuation were 1.8-11 cm in longest diameter. A focal, isolated area of ground-glass attenuation changed into mixed areas with consolidation at serial CT in one patient. Mucinous and nonmucinous BACs were observed in two patients each. Positron emission tomography showed false-negative results for malignancy.

CONCLUSION

Focal areas of ground-glass attenuation at CT could be an early sign of localized BAC.

Evaluation of lymph node metastases in squamous cell carcinoma of the esophagus with positron emission tomography

BACKGROUND

Previous studies suggest positron emission tomography (PET) may improve staging accuracy of esophageal cancer compared with conventional methods, especially in detecting occult distant metastases. We evaluated the accuracy of PET in the detection of lymph node metastasis prospectively with pathologic findings.

METHODS

Fifty-three patients with squamous cell carcinoma underwent whole-body PET scan and chest computed tomography (CT). The findings of PET and chest CT of 50 patients who underwent curative esophagectomy with radical lymph node dissection were compared with the pathologic findings.

RESULTS

Among 53 primary esophageal tumors, PET detected 51 (96.2%) and CT detected 49 (92.5%) tumors correctly. Nodal metastases were present in 108 of 436 dissected lymph node groups. PET detected 56 metastatic node groups (51.9% sensitivity, 94.2% specificity, 83.7% accuracy), compared with CT, which detected 16 (14.8% sensitivity, 96.7% specificity, 76.6% accuracy; sensitivity: p < 0.005).

CONCLUSIONS

PET was more sensitive than CT in the detection of nodal metastases and may improve staging of squamous cell carcinoma of the esophagus.

A molecular dynamics computer simulation study of room-temperature ionic liquids. II. Equilibrium and nonequilibrium solvation dynamics

The molecular dynamics (MD) simulation study of solvation structure and free energetics in 1-ethyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium hexafluorophosphate using a probe solute in the preceding article [Y. Shim, M. Y. Choi and H. J. Kim, J. Chem. Phys. 122, 044510 (2005)] is extended to investigate dynamic properties of these liquids. Solvent fluctuation dynamics near equilibrium are studied via MD and associated time-dependent friction is analyzed via the generalized Langevin equation. Nonequilibrium solvent relaxation following an instantaneous change in the solute charge distribution and accompanying solvent structure reorganization are also investigated. Both equilibrium and nonequilibrium solvation dynamics are characterized by at least two vastly different time scales--a subpicosecond inertial regime followed by a slow diffusive regime. Solvent regions contributing to the subpicosecond nonequilibrium relaxation are found to vary significantly with initial solvation configurations, especially near the solute. If the solvent density near the solute is sufficiently high at the outset of the relaxation, subpicosecond dynamics are mainly governed by the motions of a few ions close to the solute. By contrast, in the case of a low local density, solvent ions located not only close to but also relatively far from the solute participate in the subpicosecond relaxation. Despite this difference, linear response holds reasonably well in both ionic liquids.

A molecular dynamics computer simulation study of room-temperature ionic liquids. I. Equilibrium solvation structure and free energetics

Solvation in 1-ethyl-3-methylmidazolium chloride and in 1-ethyl-3-methylimidazolium hexafluorophosphate near equilibrium is investigated via molecular dynamics computer simulations with diatomic and benzenelike molecules employed as probe solutes. It is found that electrostriction plays an important role in both solvation structure and free energetics. The angular and radial distributions of cations and anions become more structured and their densities near the solute become enhanced as the solute charge separation grows. Due to the enhancement in structural rigidity induced by electrostriction, the force constant associated with solvent configuration fluctuations relevant to charge shift and transfer processes is also found to increase. The effective polarity and reorganization free energies of these ionic liquids are analyzed and compared with those of highly polar acetonitrile. Their screening behavior of electric charges is also investigated.

Outcomes after repeated resection for recurrent pulmonary metastases from colorectal cancer

BACKGROUND

It remains controversial whether metastasectomy is still feasible in patients with pulmonary recurrence from colorectal cancer, after initial metastasectomy. The aim of this study was to evaluate outcomes of repeated metastasectomy in these patients.

MATERIALS AND METHODS

From 1995 to 2007, 202 patients had received a pulmonary metastasectomy from colorectal cancer at our institution. Over a median follow-up of 28.9 months, 48 patients received second metastasectomy (29 wedge resections, 5 segmentectomies, 13 lobectomies, and 1 completion pneumonectomy). The median disease-free interval was 9.6 months. Among these 48 patients, 28 showed pulmonary recurrence again and of those, 10 patients received third metastasectomy (two wedge resections, two segmentectomies, four lobectomies, and two completion pneumonectomies).

RESULTS

There was no postoperative mortality. Of the 48 patients who underwent second metastasectomy, overall and disease-free 5-year survivals were 79% and 49%, respectively, after second operation. Of the 10 patients who received third metastasectomy, overall survival was 78% at 5 years after last operation.

CONCLUSIONS

Repeated resection after initial metastasectomy can be carried out safely and provides long-term survival in patients with recurrent pulmonary metastasis from colorectal cancer. Our findings indicate that close follow-up for the early detection of recurrence and parenchyma-saving resection can improve the results after repeated resection.

Large cell neuroendocrine carcinoma of the lung: clinical, CT, and pathologic findings in 11 patients

The purpose of this study was to describe the clinical, computed tomographic (CT), and pathologic findings of large cell neuroendocrine carcinoma (LCNEC) of the lung. CT and pathologic findings as well as clinical features of surgically proven LCNEC of the lung were reviewed retrospectively in 11 consecutive patients (eight men and three women; mean age, 63 years; range, 44-77 years). Chest CT showed peripheral mass or nodule (n = 8) and central mass with distal atelectasis (n = 3). Six tumors were accompanied by mediastinal (n = 3) and hilar (n = 3) lymph node enlargement at CT. On pathologic examination, all resected tumors showed necrosis of variable extent (mean: 38%, range; 10-70%). The areas of intrinsic lipoid pneumonia and tumor emboli in two patients appeared at CT as areas of ground-glass opacity surrounding the tumor. Mediastinal nodal metastases were seen in three (27%) patients. Pathologic staging of 11 patients was IB in six, IIA in one, IIB in one, IIIA in two, and IIIB in one. Follow-up data showed extrathoracic metastases in four patients at mean follow-up period of 15 months. One patient died of distant metastasis 5 months after the surgery. CT findings of LCNEC of the lung are nonspecific and similar to those of other non-small cell lung cancers and extrathoracic metastasis is seen in approximately one third of the patients with follow-up study.

Esophageal resection: indications, techniques, and radiologic assessment

Various surgical procedures are performed for benign and malignant esophageal lesions. These procedures include transthoracic esophageal resection through a right or left thoracotomy and transhiatal blunt esophageal resection (esophagectomy) without thoracotomy. The whole stomach, colon, gastric tube, jejunum, and free revascularized grafts may be used as substitutes for the resected esophagus. Bypass procedures including substernal stomach bypass surgery and substernal or subcutaneous colon bypass surgery are performed for tracheoesophageal fistula, previous esophagectomy without reconstruction, or obstruction due to lye ingestion. The mortality rate for esophageal resection depends on the stage of the tumor, the patient's condition, and the surgeon's skill and is quite low when the procedure is performed by a highly skilled surgeon. The most frequent sources of morbidity related to esophageal surgery include pneumothorax, pleural effusion, pneumonia, and respiratory failure. Mediastinitis and sepsis due to disruption at an anastomosis site cause serious postoperative morbidity and mortality; therefore, thoracic anastomotic leaks require aggressive surgical treatment. Familiarity with these surgical options, the resultant anatomic changes associated with each option, and the expected findings at postoperative imaging is essential for evaluating the effectiveness of surgical procedures and for the early detection and management of surgery-related complications.

Spectrum of neurogenic tumors in the thorax: CT and pathologic findings

Neurilemomas and neurofibromas appear as round soft tissue masses at CT. Variable enhancement with either homogeneity or heterogeneity is seen in neurilemomas. Attenuation of the tumors on enhanced CT depends on histology: the extent of Antoni A or B tissue and the amount of myxoid or cystic degeneration or hemorrhage. Neurofibromas are usually homogeneous low attenuation lesions on unenhanced CT. They show homogeneous enhancement or early central blush on enhanced scan. The extent of enhancement depends on the proportions of tumor components: nerve sheath cells, collagen bundles, and areas of myxoid degeneration. Malignant nerve sheath tumors show variable attenuation. Bony destruction, pleural effusion, and metastatic pulmonary nodules may also occur. Ganglioneuromas appear as oblong homogeneous low attenuation lesions on both enhanced and unenhanced CT. This low attenuation is due to their pathologic components, with an abundant amount of myxoid matrices and a relatively small amount of ganglion cells. Neuroblastomas appear as aggressive soft tissue lesions with calcification. Ganglioneuroblastomas may appear with features in between those of ganglioneuromas and neuroblastomas. The typical location of the posterior mediastinum or the aortopulmonary window and high enhancement with administration of contrast medium at CT suggest the diagnosis of paragangliomas.

Consumer misperceptions of diet quality

OBJECTIVE

This study compares consumers' self-perceived diet quality with calculated diet quality to assess the degree of consumer misperception regarding one's own diet quality and to identify factors associated with such misperception.

DESIGN

The perceived diet quality was measured by consumers' self-perception of the overall healthfulness of their diet. The calculated diet quality was measured by the Healthy Eating Index, a 10-component indicator of overall diet quality developed from 3 consecutive days of 1-day 24-hour dietary recall and 2-day diet record.

SUBJECTS/SETTINGS

Measures of perceived and calculated diet quality were obtained for a sample of 2862 household meal planners/preparers from the 1989-90 Continuing Survey of Food Intake by Individuals and the Diet and Health Knowledge Survey.

OUTCOME

Dietary misperception was assessed by classifying respondents based on categories of perceived and calculated diet quality into three groups: optimists, realists, and pessimists.

STATISTICAL ANALYSES

Bivariate statistical tests and multivariate logistic regression were used for comparing the characteristics of optimists with the other two groups.

RESULTS

An estimated 40% of the population of household meal planner/preparers were optimists who perceived the quality of their diets to be better than their calculated diet quality. In multivariate analysis, household size, gender, education, smoking status, perceived health status, importance of nutrition in grocery shopping, and belief about the need for dietary change were found to be significant predictors of being optimistic about diet quality. Nutritionists and health professionals need to be aware of this misperception and alert dietary optimists about their false perceptions of diet quality.

Upper gastrointestinal tract malignant obstruction: initial results of palliation with a flexible covered stent

The authors treated 21 patients with inoperable upper gastrointestinal tract malignant obstruction from the esophagus to the duodenum by means of intubation with a flexible covered stent with fluoroscopic guidance. Stent placement was successful and relief of dysphagia was immediate in 18 (86%) patients, without serious complication. The average dysphagia score decreased from 2.6 (dysphagia to liquids) to 1.0 (dysphagia to normal solid food). Placement of a flexible covered stent provides easy, safe, and effective palliation of upper gastrointestinal malignant obstruction.

Video-assisted thoracic surgery as a primary therapy for primary spontaneous pneumothorax. Decision making by the guideline of high-resolution computed tomography

BACKGROUND

Because blebs are confirmed in most of the patients undergoing thoracotomy, identification of blebs by high-resolution computed tomography (HRCT) can be proposed as a surgical indication in primary spontaneous pneumothorax (PSP). If an apical bleb is identified, we treat the patient by video-assisted thoracic surgery (VATS).

METHODS

From May 1995 to September 1997, 61 patients (21.9 +/- 4.6 years) were seen for initial episodes of PSP. Only seven showed bullae on simple chest radiography. However, by HRCT, 48 had sizable blebs (>5 mm), and 45 were treated surgically by VATS.

RESULTS

The mean duration of chest tube use after surgery was 3.2 +/- 1.9 days, and the mean hospital stay was 4.5 +/- 1.9 days. Only one recurrence developed 5 weeks after VATS.

CONCLUSIONS

Our protocol is effective in controlling an initial episode of PSP. It shortens the observation time before definitive surgical treatment, shortens the hospital stay, and decreases the likelihood of recurrence.

Role of leukotriene A4 hydrolase aminopeptidase in the pathogenesis of emphysema

The leukotriene A4 hydrolase (LTA4H) is a bifunctional enzyme with epoxy hydrolase and aminopeptidase activities. We hypothesize that the LTA4H aminopeptidase activity alleviates neutrophilic inflammation, which contributes to cigarette smoke (CS)-induced emphysema by clearing proline-glycine-proline (PGP), a triamino acid chemokine known to induce chemotaxis of neutrophils. To investigate the biological contributions made by the LTA4H aminopeptidase activity in CS-induced emphysema, we exposed wild-type mice to CS over 5 mo while treating them with a vehicle or a pharmaceutical agent (4MDM) that selectively augments the LTA4H aminopeptidase without affecting the bioproduction of leukotriene B4. Emphysematous phenotypes were assessed by premortem lung physiology with a small animal ventilator and by postmortem histologic morphometry. CS exposure acidified the airspaces and induced localization of the LTA4H protein into the nuclei of the epithelial cells. This resulted in accumulation of PGP in the airspaces by suppressing the LTA4H aminopeptidase activity. When the LTA4H aminopeptidase activity was selectively augmented by 4MDM, the levels of PGP in the bronchoalveolar lavage fluid and infiltration of neutrophils into the lungs were significantly reduced without affecting the levels of leukotriene B4. This protected murine lungs from CS-induced emphysematous alveolar remodeling. In conclusion, CS exposure promotes the development of CS-induced emphysema by suppressing the enzymatic activities of the LTA4H aminopeptidase in lung tissues and accumulating PGP and neutrophils in the airspaces. However, restoring the leukotriene A4 aminopeptidase activity with a pharmaceutical agent protected murine lungs from developing CS-induced emphysema.

AKR1B10 is associated with smoking and smoking-related non-small-cell lung cancer

This prospective study explored the relationship between expression of AKR1B10 mRNA and various clinical parameters in non-small-cell lung cancer (NSCLC) in terms of its validation as a marker for NSCLC. Tumour tissue samples were collected from 229 patients with NSCLC. Tissue samples from adjacent non-malignant lung tissue (> 5 cm from the tumour) of 89 of these patients and samples from 20 patients with benign lung disease were used as controls. Quantitative reverse transcription- polymerase chain reaction showed significantly higher levels of AKR1B10 mRNA expression in NSCLC tumour tissue than in adjacent non-malignant lung tissue and benign lung tissue. Statistically significant factors for AKR1B10 mRNA over-expression were found to be male gender, smoking, squamous cell carcinoma and moderate or poor cell differentiation. It is concluded that AKR1B10 seems to have potential as a prognostic marker for NSCLC and warrants further investigation.

Giant fibrovascular polyp of the esophagus: CT findings

Giant fibrovascular polyp of the esophagus is a rare intraluminal benign tumor that is covered with normal esophageal mucosa, which consists of fibrous tissue, adipose tissue, and vascular structures. We report a case of a giant fibrovascular polyp of the esophagus in which feeding vessels were well visualized within the stalk of the mass at contrast-enhanced helical computed tomography.

Probing Changes in Lung Physiology in COPD Using CT, Perfusion MRI, and Hyperpolarized Xenon-129 MRI

RATIONALE AND OBJECTIVES

Chronic obstructive pulmonary disease (COPD) is highly heterogeneous and not well understood. Hyperpolarized xenon-129 (Xe129) magnetic resonance imaging (MRI) provides a unique way to assess important lung functions such as gas uptake. In this pilot study, we exploited multiple imaging modalities, including computed tomography (CT), gadolinium-enhanced perfusion MRI, and Xe129 MRI, to perform a detailed investigation of changes in lung morphology and functions in COPD. Utility and strengths of Xe129 MRI in assessing COPD were also evaluated against the other imaging modalities.

MATERIALS AND METHODS

Four COPD patients and four age-matched normal subjects participated in this study. Lung tissue density measured by CT, perfusion measures from gadolinium-enhanced MRI, and ventilation and gas uptake measures from Xe129 MRI were calculated for individual lung lobes to assess regional changes in lung morphology and function, and to investigate correlations among the different imaging modalities.

RESULTS

No significant differences were found for all measures among the five lobes in either the COPD or age-matched normal group. Strong correlations (R > 0.5 or < -0.5, p < 0.001) were found between ventilation and perfusion measures. Also gas uptake by blood as measured by Xe129 MRI showed strong correlations with CT tissue density and ventilation measures (R > 0.5 or < -0.5, p < 0.001) and moderate to strong correlations with perfusion measures (R > 0.4 or < -0.5, p < 0.01). Four distinctive patterns of functional abnormalities were found in patients with COPD.

CONCLUSION

Xe129 MRI has high potential to uniquely identify multiple changes in lung physiology in COPD using a single breath-hold acquisition.

T1 lung cancer on CT: frequency of extrathoracic metastases

PURPOSE

To determine the frequency of extrathoracic metastases in T1 non-small-cell lung cancer.

METHOD

Ninety patients with T1 lung cancer identified on CT were included. Extrathoracic metastases were evaluated at the time of initial diagnosis and during a 1-year follow-up study. The frequency of metastases was compared in terms of cell type (squamous or nonsquamous), size (<2 cm or >2 cm), and the initial CT findings of the tumor.

RESULTS

Extrathoracic metastases were identified in 12 (13%) of 90 patients at the time of diagnosis and in 10 patients at the 1-year follow-up study (total, 22 of 90 [24%] patients). Tumors with ground-glass opacity on CT were associated with a significantly lower prevalence of metastases (p = 0.042). The area of ground-glass opacity was seen in 1 of 13 (85%) patients with bronchioloalveolar carcinoma and in 12 of 53 (23%) patients with adenocarcinoma other than bronchioloalveolar carcinoma (p < 0.001). There was no significant difference in the prevalence of metastases between squamous and nonsquamous cell carcinoma, between tumors smaller than 2 cm (n = 17) and larger than 2 cm in diameter (n = 73) and between tumors with or without mediastinal nodal metastases (p>0.05).

CONCLUSION

Extrathoracic metastases were apparent at the initial examination in 13% of patients and at the 1-year follow-up examination in 11% of patients. The prevalence is significantly lower in tumors with ground-glass opacity.

Malignant esophagogastric junction obstruction: palliative treatment with an antireflux valve stent

The authors assessed the efficacy of an antireflux valve stent in the palliation of malignant esophagogastric junction (EGJ) obstruction after in vitro testing of the stent. Seventeen patients with inoperable malignant EGJ obstruction were treated. Antireflux valves, made of three polyurethane leaflets, were attached to the distal part of the stent to prevent reflux. When the flow rate of normal saline was 100 mL/sec in the forward direction, the valve fully opened at a pressure of 10 mm Hg. When the flow rate of normal saline was 0.35 mL/sec in the backward direction, the valve nearly completely closed at a pressure of 10 mm Hg. Stent placement was successful in all patients without complications. The median dysphagia score decreased significantly, from 3.0 (dysphagia to liquids) to 1.0 (dysphagia to normal solid food) (P < .0005). No patients experienced reflux symptoms. There was one case of stent migration. A valve stent that can prevent major reflux is an effective device for the palliation of malignant EGJ obstruction.

Role of LTB₄ in the pathogenesis of elastase-induced murine pulmonary emphysema

Exaggerated levels of the leukotriene B₄ (LTB₄) frequently coexist at sites of inflammation and tissue remodeling. Therefore, we hypothesize that the LTB₄ pathway plays an important role in the pathogenesis of neutrophilic inflammation that contributes to pulmonary emphysema. In this study, significant levels of LTB₄ were detected in human lung tissues with emphysema compared with lungs without emphysema (9,497 ± 2,839 vs. 4,142 ± 1,173 pg/ml, n = 9 vs. 10, P = 0.04). To further determine the biological role of LTB₄ in the pathogenesis of emphysema, we compared the lungs of wild-type (WT) and LTA₄ hydrolase-/- mice (LTB₄ deficient, LTA₄H-/-) exposed to intranasal elastase or vehicle control. We found that intranasal elastase induced accumulation of LTB₄ in the lungs and caused progressively worsening emphysema between 14 and 28 days after elastase exposure in WT mice but not in LTA₄H-/- mice. Premortem physiology documented increased lung compliance in elastase-exposed WT mice compared with elastase-exposed LTA₄H-/- mice as measured by Flexivent (0.058 ± 0.005 vs. 0.041 ± 0.002 ml/cmH₂O pressure). Postmortem morphometry documented increased total lung volume and alveolar sizes in elastase-exposed WT mice compared with elastase-exposed LTA₄H-/- mice as measured by volume displacement and alveolar chord length assessment. Furthermore, elastase-exposed LTA₄H-/- mice were found to have significantly delayed influx of the CD45(high)CD11b(high)Ly6G(high) leukocytes compatible with neutrophils compared with elastase-exposed WT mice. Mechanistic insights to these phenotypes were provided by demonstrating protection from elastase-induced murine emphysema with neutrophil depletion in the elastase-exposed WT mice and by demonstrating time-dependent modulation of cysteinyl leukotriene biosynthesis in the elastase-exposed LTA₄H-/- mice compared with elastase-exposed WT mice. Together, these findings demonstrated that LTB₄ played an important role in promoting the pathogenesis of pulmonary emphysema associated with neutrophilic pulmonary inflammation.

Arterial windkessel parameter estimation: a new time-domain method

We developed and validated a new, more accurate, and easily applied method for calculating the parameters of the three-element Windkessel to quantitate arterial properties and to investigate ventriculoarterial coupling. This method is based on integrating the governing differential equation of the three-element Windkessel and solving for arterial compliance. It accounts for the interaction between characteristic impedance and compliance, an important phenomenon that has been ignored by previously implemented methods. The new integral method was compared with four previously published methods as well as a new independent linear least-squares analysis, using ascending aortic micromanometric and volumetric flow measurements from eight dogs. The parameters calculated by the new integral method were found to be significantly different from those obtained by the previous methods but did not differ significantly from maximum likelihood estimators obtained by a linear least-squares approach. To assess the accuracy of parameter estimation, pressure and flow waveforms were reconstructed in the time domain by numerically solving the governing differential equation of the three-element Windkessel model. Standard deviations of reconstructed waveforms from the experimental ensemble-averaged waveforms, which solely reflect the relative accuracy of the Windkessel parameters given by the various methods, were calculated. The new integral method invariably yielded the smallest error. These results demonstrate the improved accuracy of our new integral method in estimating arterial parameters of the three-element Windkessel.

Emphysema Index Based on Hyperpolarized 3He or 129Xe Diffusion MRI: Performance and Comparison with Quantitative CT and Pulmonary Function Tests

Background Apparent diffusion coefficient (ADC) maps of inhaled hyperpolarized gases have shown promise in the characterization of emphysema in patients with chronic obstructive pulmonary disease (COPD), yet an easily interpreted quantitative metric beyond mean and standard deviation has not been established. Purpose To introduce a quantitative framework with which to characterize emphysema burden based on hyperpolarized helium 3 (3He) and xenon 129 (129Xe) ADC maps and compare its diagnostic performance with CT-based emphysema metrics and pulmonary function tests (PFTs). Materials and Methods Twenty-seven patients with mild, moderate, or severe COPD and 13 age-matched healthy control subjects participated in this retrospective study. Participants underwent CT and multiple b value diffusion-weighted 3He and 129Xe MRI examinations and standard PFTs between August 2014 and November 2017. ADC-based emphysema index was computed separately for each gas and b value as the fraction of lung voxels with ADC values greater than in the healthy group 99th percentile. The resulting values were compared with quantitative CT results (relative lung area <-950 HU) as the reference standard. Diagnostic performance metrics included area under the receiver operating characteristic curve (AUC). Spearman rank correlations and Wilcoxon rank sum tests were performed between ADC-, CT-, and PFT-based metrics, and intraclass correlation was performed between repeated measurements. Results Thirty-six participants were evaluated (mean age, 60 years ± 6 [standard deviation]; 20 women). ADC-based emphysema index was highly repeatable (intraclass correlation coefficient > 0.99) and strongly correlated with quantitative CT (r = 0.86, P < .001 for 3He; r = 0.85, P < .001 for 129Xe) with high AUC (≥0.93; 95% confidence interval [CI]: 0.85, 1.00). ADC emphysema indices were also correlated with percentage of predicted diffusing capacity of lung for carbon monoxide (r = -0.81, P < .001 for 3He; r = -0.80, P < .001 for 129Xe) and percentage of predicted residual lung volume divided by total lung capacity (r = 0.65, P < .001 for 3He; r = 0.61, P < .001 for 129Xe). Conclusion Emphysema index based on hyperpolarized helium 3 or xenon 129 diffusion MRI provides a repeatable measure of emphysema burden, independent of gas or b value, with similar diagnostic performance as quantitative CT or pulmonary function metrics. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Schiebler and Fain in this issue.

A single institutional experience of thymic epithelial tumours over 11 years: clinical features and outcome and implications for future management

Thymic epithelial tumours (TETs), the most common tumour of the anterior mediastinum, are epithelial neoplasms of the thymus with a wide spectrum of morphologic features. We retrospectively analysed clinical features of TET and the correlation of World Health Organisation (WHO) histologic classification and Masaoka staging system with different treatment modalities in 195 patients, from 1995 to 2005. According to the Masaoka's staging system, there were 78 (40.0 %) patients with stage I, 38 (19.5%) with stage II, 41 (21.0%) with stage III, 38 (19.5%) with stage IV. All patients were reclassified according to the WHO criteria as follows: Type A (n=9, 4.6%), AB (n=37, 18.9%), B1 (n=29, 14.8%), B2 (n=48, 24.6%), B3 (n=40, 20.5%), C (n=32, 16.4%). There was a fairly good correlation between Masaoka staging and WHO histotype (P<0.05). However, in multivariate analysis, the tumour stage and WHO histotype were two independent factors separately for predicting overall survival (P<0.001, P<0.001, respectively). Thus, both Masaoka stage and WHO histotype should be considered in risk stratification of therapy for TET patients. Patients with completely resected types B2, B3 and C and adjuvant radiotherapy (n=57) had more favourable disease-free and overall survival as compared with those without adjuvant treatment (n=20) (P=0.015, 0.015, respectively). Given that the predominant sites of recurrence after surgery was pleura/pericardium and lung, and the fact that complete resection was a significant influential factor for survival at log–rank test, an active investigation of newer treatment strategies such as neoadjuvant treatment to improve the resectability and development of optimal adjuvant treatment modality is a high priority especially for those with high-risk for recurrence or in patients with advanced stage disease.

Recurrence of squamous cell carcinoma of the oesophagus after curative surgery: rates and patterns on imaging studies correlated with tumour location and pathological stage

Many factors have been related to recurrence after resection of squamous cell carcinoma of the oesophagus. These include age, gender, location and local stage of tumours, cell differentiation, lymph node metastasis and vascular involvement. The recurrence rates of squamous cell carcinoma after curative surgery are high (34-79%). Tumour recurrence is categorized as locoregional or distant. Lymph node recurrence and haematogenous metastasis to solid organs (commonly to the lung) are the usual patterns of recurrence. Awareness of recurrence patterns, particularly on imaging studies, is essential for the diagnosis of recurrent tumours on follow-up examinations.