Oxygen-enhanced MR Imaging: Correlation with Postsurgical Lung Function in Patients with Lung Cancer

Lung Magnetic Resonance Imaging: Technical Advancements and Clinical Applications

ABSTRACT

Since lung magnetic resonance imaging (MRI) became clinically available, limited clinical utility has been suggested for applying MRI to lung diseases. Moreover, clinical applications of MRI for patients with lung diseases or thoracic oncology may vary from country to country due to clinical indications, type of health insurance, or number of MR units available. Because of this situation, members of the Fleischner Society and of the Japanese Society for Magnetic Resonance in Medicine have published new reports to provide appropriate clinical indications for lung MRI. This review article presents a brief history of lung MRI in terms of its technical aspects and major clinical indications, such as (1) what is currently available, (2) what is promising but requires further validation or evaluation, and (3) which developments warrant research-based evaluations in preclinical or patient studies. We hope this article will provide Investigative Radiology readers with further knowledge of the current status of lung MRI and will assist them with the application of appropriate protocols in routine clinical practice.

Review of oxygen-enhanced lung mri: Pulse sequences for image acquisition and T1 measurement

Oxygen-enhanced MR imaging (OE-MRI) is a special proton imaging technique that can be performed without modifying the scanner hardware. Many fundamental studies have been conducted following the initial reporting of this technique in 1996, illustrating the high potential for its clinical application. This review aims to summarise and analyse current pulse sequences and T1 measurement methods for OE-MRI, including fundamental theories, existing pulse sequences applied to OE-MRI acquisition and T1 mapping. Wash-in and wash-out time identify lung function and are sensitive to ventilation; thus, dynamic OE-MRI is also discussed in this review. We compare OE-MRI with the primary competitive technique, hyperpolarised gas MRI. Finally, an overview of lower-field applications of OE-MRI is highlighted, as relatively recent publications demonstrated positive results. Lower-field OE-MRI, which is lower than 1.5 T, could be an alternative modality for detecting lung diseases. This educational review is aimed at researchers who want a quick summary of the steps needed to perform pulmonary OE-MRI with a particular focus on sequence design, settings, and quantification methods.

State-of-the-art MR Imaging for Thoracic Diseases

Since thoracic MR imaging was first used in a clinical setting, it has been suggested that MR imaging has limited clinical utility for thoracic diseases, especially lung diseases, in comparison with x-ray CT and positron emission tomography (PET)/CT. However, in many countries and states and for specific indications, MR imaging has recently become practicable. In addition, recently developed pulmonary MR imaging with ultra-short TE (UTE) and zero TE (ZTE) has enhanced the utility of MR imaging for thoracic diseases in routine clinical practice. Furthermore, MR imaging has been introduced as being capable of assessing pulmonary function. It should be borne in mind, however, that these applications have so far been academically and clinically used only for healthy volunteers, but not for patients with various pulmonary diseases in Japan or other countries. In 2020, the Fleischner Society published a new report, which provides consensus expert opinions regarding appropriate clinical indications of pulmonary MR imaging for not only oncologic but also pulmonary diseases. This review article presents a brief history of MR imaging for thoracic diseases regarding its technical aspects and major clinical indications in Japan 1) in terms of what is currently available, 2) promising but requiring further validation or evaluation, and 3) developments warranting research investigations in preclinical or patient studies. State-of-the-art MR imaging can non-invasively visualize lung structural and functional abnormalities without ionizing radiation and thus provide an alternative to CT. MR imaging is considered as a tool for providing unique information. Moreover, prospective, randomized, and multi-center trials should be conducted to directly compare MR imaging with conventional methods to determine whether the former has equal or superior clinical relevance. The results of these trials together with continued improvements are expected to update or modify recommendations for the use of MRI in near future.

Pulmonary Functional Imaging: Part 1-State-of-the-Art Technical and Physiologic Underpinnings

Over the past few decades, pulmonary imaging technologies have advanced from chest radiography and nuclear medicine methods to high-spatial-resolution or low-dose chest CT and MRI. It is currently possible to identify and measure pulmonary pathologic changes before these are obvious even to patients or depicted on conventional morphologic images. Here, key technological advances are described, including multiparametric CT image processing methods, inhaled hyperpolarized and fluorinated gas MRI, and four-dimensional free-breathing CT and MRI methods to measure regional ventilation, perfusion, gas exchange, and biomechanics. The basic anatomic and physiologic underpinnings of these pulmonary functional imaging techniques are explained. In addition, advances in image analysis and computational and artificial intelligence (machine learning) methods pertinent to functional lung imaging are discussed. The clinical applications of pulmonary functional imaging, including both the opportunities and challenges for clinical translation and deployment, will be discussed in part 2 of this review. Given the technical advances in these sophisticated imaging methods and the wealth of information they can provide, it is anticipated that pulmonary functional imaging will be increasingly used in the care of patients with lung disease. © RSNA, 2021 Online supplemental material is available for this article.

Overview of MRI for pulmonary functional imaging

Morphological evaluation of the lung is important in the clinical evaluation of pulmonary diseases. However, the disease process, especially in its early phases, may primarily result in changes in pulmonary function without changing the pulmonary structure. In such cases, the traditional imaging approaches to pulmonary morphology may not provide sufficient insight into the underlying pathophysiology. Pulmonary imaging community has therefore tried to assess pulmonary diseases and functions utilizing not only nuclear medicine, but also CT and MR imaging with various technical approaches. In this review, we overview state-of-the art MR methods and the future direction of: (1) ventilation imaging, (2) perfusion imaging and (3) biomechanical evaluation for pulmonary functional imaging.

3D Oxygen-Enhanced MRI at 3T MR System: Comparison With Thin-Section CT of Quantitative Capability for Pulmonary Functional Loss Assessment and Clinical Stage Classification of COPD in Smokers

BACKGROUND

Oxygen (O₂ )-enhanced MRI is mainly performed by a 2D sequence using 1.5T MR systems but trying to be obtained by a 3D sequence using a 3T MR system.

PURPOSE

To compare the capability of 3D O₂ -enhanced MRI and that of thin-section computed tomography (CT) for pulmonary functional loss assessment and clinical stage classification of chronic obstructive pulmonary disease (COPD) in smokers.

STUDY TYPE

Prospective study.

POPULATION

Fifty six smokers were included.

FIELD STRENGTH/ SEQUENCE

3T, 3D O₂ -enhanced MRIs were performed with a 3D T₁ -weighted fast field echo pulse sequence using the multiple flip angles.

ASSESSMENTS

Smokers were classified into four stages ("Without COPD," "Mild COPD," "Moderate COPD," "Severe or very severe COPD"). Maps of regional changes in T₁ values were generated from O₂ -enhanced MR data. Regions of interest (ROIs) were then placed over the lung on all slices and averaged to determine mean T₁ value change (ΔT₁ ). Quantitative CT used the percentage of low attenuation areas within the entire lung (LAA%).

STATISTICAL TESTS

ΔT₁ and LAA% were correlated with pulmonary functional parameters, and compared for four stages using Tukey's Honestly Significant Difference test. Discrimination analyses were performed and McNemar's test was used for a comparison of the accuracy of the indexes.

RESULTS

There were significantly higher correlations between ΔT₁ and pulmonary functional parameters (-0.83 ≤ r ≤ -0.71, P < 0.05) than between LAA% and the same pulmonary functional parameters (-0.76 ≤ r ≤ -0.69, P < 0.05). ΔT₁ and LAA% of the "Mild COPD" and "Moderate COPD" groups were significantly different from those of the "Severe or Very Severe COPD" group (P < 0.05). Discriminatory accuracy of ΔT₁ (62.5%) and ΔT1 with LAA% (67.9%) was significantly greater than that of LAA% (48.2%, P < 0.05).

DATA CONCLUSION

Compared with thin-section CT, 3D O₂ -enhanced MRI has a similar capability for pulmonary functional assessment but better potential for clinical stage classification in smokers.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 1.

Ventilation/Perfusion Relationships and Gas Exchange: Measurement Approaches

Ventilation-perfusion ( V ˙ A / Q ˙ ) matching, the regional matching of the flow of fresh gas to flow of deoxygenated capillary blood, is the most important mechanism affecting the efficiency of pulmonary gas exchange. This article discusses the measurement of V ˙ A / Q ˙ matching with three broad classes of techniques: (i) those based in gas exchange, such as the multiple inert gas elimination technique (MIGET); (ii) those derived from imaging techniques such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), computed tomography (CT), and electrical impedance tomography (EIT); and (iii) fluorescent and radiolabeled microspheres. The focus is on the physiological basis of these techniques that provide quantitative information for research purposes rather than qualitative measurements that are used clinically. The fundamental equations of pulmonary gas exchange are first reviewed to lay the foundation for the gas exchange techniques and some of the imaging applications. The physiological considerations for each of the techniques along with advantages and disadvantages are briefly discussed. © 2020 American Physiological Society. Compr Physiol 10:1155-1205, 2020.

The effect of flow on blood oxygen level dependent (R* 2 ) MRI of orthotopic lung tumors

PURPOSE

Blood oxygen level dependent (BOLD) MRI based on R 2 * measurements can provide insights into tumor vascular oxygenation. However, measurements are susceptible to blood flow, which may vary accompanying a hyperoxic gas challenge. We investigated flow sensitivity by comparing R 2 * measurements with and without flow suppression (fs) in 2 orthotopic lung xenograft tumor models.

METHODS

H460 (n = 20) and A549 (n = 20) human lung tumor xenografts were induced by surgical implantation of cancer cells in the right lung of nude rats. MRI was performed at 4.7T after tumors reached 5 to 8 mm in diameter. A multiecho gradient echo MRI sequence was acquired with and without spatial saturation bands on each side of the imaging plane to evaluate the effect of flow on R 2 * . fs and non-fs R 2 * MRI measurements were interleaved during an oxygen breathing challenge (from air to 100% O₂ ). T 2 * -weighted signal intensity changes (ΔSI(%)) and R 2 * measurements were obtained for regions of interest and on a voxel-by-voxel basis and discrepancies quantified with Bland-Altman analysis.

RESULTS

Flow suppression affected ΔSI(%) and R 2 * measurements in each tumor model. Average discrepancy and limits of agreement from Bland-Altman analyses revealed greater flow-related bias in A549 than H460.

CONCLUSION

The effect of flow on R 2 * , and hence BOLD, was tumor model dependent with measurements being more sensitive in well-perfused A549 tumors.

Gadolinium-Based Blood Volume Mapping From MRI With Ultrashort TE Versus CT and SPECT for Predicting Postoperative Lung Function in Patients With Non-Small Cell Lung Cancer

OBJECTIVE

The purpose of this study is to directly compare the capability of gadolinium-based blood volume (BV) mapping from MRI (BV-MRI) with ultrashort TE (UTE) with that of CT and perfusion SPECT in predicting the postoperative lung function of patients with non-small cell lung cancer (NSCLC).

SUBJECTS AND METHODS

Unenhanced and contrast-enhanced MRI with UTE, thin-section CT, and perfusion SPECT examinations and measurements of the percentage of forced expiratory volume in 1 second (FEV₁) before and after lung resection were performed for 29 patients with NSCLC (16 men [mean age, 66 years] and 13 women [mean age, 66 years]). BV-MRI with UTE was generated as a percentage of the signal change between unenhanced and contrast-enhanced MRI. The postoperative percentage of FEV₁ was predicted from perfusion fractions derived from BV-MRI with UTE and from SPECT. Quantitatively and qualitatively predicted postoperative percentages of FEV₁ from CT were calculated from the functional lung volumes and the number of segments. Each predicted postoperative percentage of FEV₁ was then correlated with the actual postoperative percentage of FEV₁, and the limits of agreement for each actual and predicted postoperative percentage of FEV₁ were evaluated by Bland-Altman analysis.

RESULTS

Correlations between actual and predicted postoperative percentages of FEV₁ for all methods were strong and significant (0.88 ≤ r ≤ 0.95). The limits of agreement (mean ± 1.96 × SD) for BV-MRI with UTE (4.2% ± 6.5%) and quantitatively assessed CT (4.1% ± 6.5%) were smaller than those for qualitatively assessed CT (4.2% ± 9.8%) and perfusion SPECT (5.7% ± 8.7%).

CONCLUSION

BV-MRI with UTE has the potential to predict the postoperative lung function of patients with NSCLC more accurately than qualitatively assessed CT and SPECT, and it can be considered to be at least as useful as quantitatively assessed CT.

Complementary regional heterogeneity information from COPD patients obtained using oxygen-enhanced MRI and chest CT

Background

The heterogeneous distribution of emphysema is a key feature of chronic obstructive pulmonary disease (COPD) patients that typically is evaluated using high-resolution chest computed tomography (HRCT). Oxygen-enhanced pulmonary magnetic resonance imaging (OEMRI) is a new method to obtain information regarding regional ventilation, diffusion, and perfusion in the lung without radiation exposure. We aimed to compare OEMRI with HRCT for the assessment of heterogeneity in COPD patients.

Methods

Forty patients with stable COPD underwent quantitative HRCT, OEMRI, and pulmonary function tests, including arterial blood gas analysis. OEMRI was also performed on nine healthy control subjects. We measured the severity of emphysema (percent low attenuation volume; LAV%) in whole lungs and the standard deviations (SDs) of the LAV% values of 10 isovolumetric partitions (SD-LAV) as an index of cranial-caudal heterogeneity. Similarly, relative enhancement ratios of oxygen (RERs) in whole lungs from OEMRI and SD-RER were analyzed.

Results

COPD patients showed a lower mean RER than control subjects (12.6% vs 22.0%, p<0.01). The regional heterogeneity of the RERs was not always consistent with the LAV distribution. Both the HRCT (LAV% and SD-LAV) and the OEMRI (RER and SD-RER) indices were significantly associated with the diffusion capacity (DL_CO) and partial pressure of oxygen in arterial blood (PaO₂). The PaO₂ was associated only with the heterogeneity index of HRCT (SD-LAV) (R² = 0.39); however, the PaO₂ was associated with both the mean RER and heterogeneity (SD-RER) in the multivariate analysis (R² = 0.38).

Conclusions

OEMRI-derived parameters were directly associated with oxygen uptake in COPD patients. Although the OEMRI-derived parameters were not identical to the HRCT-derived parameters, the cranial-caudal heterogeneity in HRCT or OEMRI was complementary to that in evaluations of oxygen uptake in the lungs. Functional imaging seems to provide new insights into COPD pathophysiology without radiation exposure.

Protective Effect of Ginkgo biloba and Magnetized Water on Nephropathy in Induced Type 2 Diabetes in Rat

We aimed in our current study to explore the protective effect of Ginkgo biloba (GB) and magnetized water (MW) against nephrotoxicity associating induced type 2 diabetes mellitus in rat. Here, we induced diabetes by feeding our lab rats on a high fat-containing diet (4 weeks) and after that injecting them with streptozotocin (STZ). We randomly divided forty rats into four different groups: nontreated control (Ctrl), nontreated diabetic (Diabetic), Diabetic+GB (4-week treatment), and Diabetic+MW (4-week treatment). After the experiment was finished, serum and kidney tissue samples were gathered. Blood levels of glucose, triglycerides, cholesterol, creatinine, and urea were markedly elevated in the diabetic group than in the control group. In all animals treated with GB and MW, the levels of urea, creatinine, and glucose were significantly reduced (all P < 0.01). GB and MW attenuated glomerular and tubular injury as well as the histological score. Furthermore, they normalized the contents of glutathione reductase and SOD2. In summary, our data showed that GB and MW treatment protected type 2 diabetic rat kidneys from nephrotoxic damages by reducing the hyperlipidemia, uremia, oxidative stress, and renal dysfunction.

Contribution of magnetic resonance imaging in lung cancer imaging

Lung cancer is the leading cause of cancer death worldwide. Prognosis and treatment outcomes are known to be related to the disease stage at the time of diagnosis. Therefore, an accurate assessment of the extent of disease is critical to determine the most appropriate therapy. Currently available imaging modalities for diagnosis and follow-up consist of morphological and functional imaging. Morphological investigations are mainly performed with CT-scan and in some cases with MRI. In this review, we describe the contribution of MRI in lung cancer staging focusing on solid pulmonary nodule characterization and TNM staging assessment using chest and whole-body MRI examinations, detailing in each chapter current recommendations and future developments.

Functional imaging of the lungs with gas agents

This review focuses on the state-of-the-art of the three major classes of gas contrast agents used in magnetic resonance imaging (MRI)-hyperpolarized (HP) gas, molecular oxygen, and fluorinated gas--and their application to clinical pulmonary research. During the past several years there has been accelerated development of pulmonary MRI. This has been driven in part by concerns regarding ionizing radiation using multidetector computed tomography (CT). However, MRI also offers capabilities for fast multispectral and functional imaging using gas agents that are not technically feasible with CT. Recent improvements in gradient performance and radial acquisition methods using ultrashort echo time (UTE) have contributed to advances in these functional pulmonary MRI techniques. The relative strengths and weaknesses of the main functional imaging methods and gas agents are compared and applications to measures of ventilation, diffusion, and gas exchange are presented. Functional lung MRI methods using these gas agents are improving our understanding of a wide range of chronic lung diseases, including chronic obstructive pulmonary disease, asthma, and cystic fibrosis in both adults and children.

Measurement of preoperative lobar lung function with computed tomography ventilation imaging: progress towards rapid stratification of lung cancer lobectomy patients with abnormal lung function

OBJECTIVES

In lung cancer preoperative evaluation, functional lung imaging is commonly used to assess lobar function. Computed tomography ventilation (CT-V) imaging is an emerging lung function imaging modality. We compared CT-V imaging assessment of lobar function and its prediction of postoperative lung function to that achieved by (i) positron emission tomography ventilation (PET-V) imaging and (ii) the standard anatomical segment counting (ASC) method. We hypothesized (i) that CT-V and PET-V have similar relative lobar function and (ii) that functional imaging and anatomic assessment (ASC) yield different predicted postoperative (ppo) lung function and therefore could change clinical management.

METHODS

In this proof-of-concept study, 11 patients were subjected to pulmonary function tests, CT-V and PET-V imaging. The Bland-Altman plot, Pearson's correlation and linear regression analysis were used to assess the agreement between the CT-V-, PET-V- and ASC-based quantification of lobar function and in the ppo lung function.

RESULTS

CT-V and PET-V imaging demonstrated strong correlations in quantifying relative lobar function (r = 0.96; P < 0.001). A Wilcoxon-signed rank test showed no significant difference in the lobar function estimates between the two imaging modalities (P = 0.83). The Bland-Altman plot also showed no significant differences. The correlation between ASC-based lobar function estimates with ventilation imaging was low, r < 0.45; however, the predictions of postoperative lung function correlated strongly between all three methods.

CONCLUSIONS

The assessment of lobar function from CT-V imaging correlated strongly with PET-V imaging, but had low correlations with ASC. CT-V imaging may be a useful alternative method in preoperative evaluation for lung cancer patients.

[Study on cine view of relative enhancement ratio map in O2-enhanced MRI]

Magnetic resonance imaging (MRI) enables the evaluation of organ structure and function. Oxygen-enhanced MRI (O2-enhanced MRI) is a method for evaluating the pulmonary ventilation function using oxygen as a contrast agent. We created the Cine View of Relative Enhancement Ratio Map (Cine RER map) in O2-enhanced MRI to easily observe the contrast effect for clinical use. Relative enhancement ratio (RER) was determined as the pixel values of the Cine RER map. Moreover, six healthy volunteers underwent O2-enhanced MRI to determine the appropriate scale width of the Cine RER map. We calculated each RER and set 0 to 1.27 as the scale width of the Cine RER map based on the results. The Cine RER map made it possible to observe the contrast effect over time and thus is a convenient tool for evaluating the pulmonary ventilation function in O2-enhanced MRI.

Physiorack: an integrated MRI safe/conditional, gas delivery, respiratory gating, and subject monitoring solution for structural and functional assessments of pulmonary function

PURPOSE

To evaluate the use of a modular MRI conditional respiratory monitoring and gating solution, designed to facilitate proper monitoring of subjects' vital signals and their respiratory efforts, during free-breathing and breathheld 19F, oxygen-enhanced, and Fourier-decomposition MRI-based acquisitions.

MATERIALS AND METHODS

All Imaging was performed on a Siemens TIM Trio 3 Tesla MRI scanner, following Institutional Review Board approval. Gas delivery is accomplished through the use of an MR compatible pneumotachometer, in conjunction with two three-way pneumatically controlled Hans Rudolph Valves. The pneumatic valves are connected to Douglas bags used as the gas source. A mouthpiece (+nose clip) or an oro-nasal Hans Rudolph disposable mask is connected following the pneumatic valve to minimize dead-space and provide an airtight seal. Continuous monitoring/sampling of inspiratory and expiratory oxygen and carbon dioxide levels at the mouthpiece/mask is achieved through the use of an Oxigraf gas analyzer.

RESULTS

Forty-four imaging sessions were successfully monitored, during Fourier-decomposition (n=3), fluorine-enhanced (n=29), oxygen-enhanced, and ultra short echo (n=12) acquisitions. The collected waveforms, facilitated proper monitoring and coaching of the subjects.

CONCLUSION

We demonstrate an inexpensive, off-the-shelf solution for monitoring these signals, facilitating assessments of lung function. Monitoring of respiratory efforts and exhaled gas concentrations assists in understanding the heterogeneity of lung function visualized by gas imaging.

Magnetic resonance imaging of pediatric lung parenchyma, airways, vasculature, ventilation, and perfusion: state of the art

Magnetic resonance (MR) imaging is a noninvasive imaging modality, particularly attractive for pediatric patients given its lack of ionizing radiation. Despite many advantages, the physical properties of the lung (inherent low signal-to-noise ratio, magnetic susceptibility differences at lung-air interfaces, and respiratory and cardiac motion) have posed technical challenges that have limited the use of MR imaging in the evaluation of thoracic disease in the past. However, recent advances in MR imaging techniques have overcome many of these challenges. This article discusses these advances in MR imaging techniques and their potential role in the evaluation of thoracic disorders in pediatric patients.

Thoracic magnetic resonance imaging for the evaluation of pulmonary emphysema

Pulmonary emphysema is a pathologic condition characterized by permanently enlarged airspaces distal to the terminal bronchiole with destruction of the alveolar walls. Functional information of the lungs is important to understand the pathophysiology of emphysema and that of chronic obstructive pulmonary disease. With the recent developments in magnetic resonance imaging (MRI) techniques, functional MRI with variable MR sequences can be used for the evaluation of different physiological and anatomic changes seen in cases of pulmonary emphysema. In this review article, we will focus on a brief description of each method, results of some of the most recent work, and the clinical application of such knowledge.

Oxygen-enhanced MRI, thin-section MDCT, and perfusion SPECT/CT: comparison of clinical implications to patient care for lung volume reduction surgery

OBJECTIVE

The purpose of our study was to prospectively and directly compare capability of O2-enhanced MRI, MDCT, and perfusion SPECT/CT to clinical outcome measurements in candidates for lung volume reduction surgery (LVRS).

SUBJECTS AND METHODS

Twenty-five consecutive candidates for LVRS (20 men and five women; age range, 45-76 years) underwent MDCT, O2-enhanced MRI, and perfusion SPECT/CT before and after LVRS. Clinical outcomes for each candidate were evaluated in terms of differences between pre- and postoperative percentage forced expiratory volume in 1 second (%FEV1), Pao2, and 6-minute walking distance. Quantitatively assessed upper/lower lung ratios on O2-enhanced MRI, MDCT, and SPECT/CT were calculated from regional relative enhancement ratios, functional lung volumes, and radioisotope uptakes between upper and lower lungs. Qualitatively assessed upper/lower lung ratios on O2-enhanced MRI, MDCT, and SPECT/CT were estimated using visual scoring systems. To evaluate the correlation for individual upper/lower lung ratios and clinical outcomes, all upper/lower lung ratios were correlated with clinical outcomes. Improvements in mean relative enhancement ratio were directly correlated with clinical outcomes to assess the capability of O2-enhanced MRI to assess therapeutic effect.

RESULTS

All quantitatively (-0.63≤r≤-0.47, p<0.05) and qualitatively (0.41≤r≤0.57, p<0.05) assessed upper/lower lung ratios showed moderate and statistically significant correlation with clinical outcomes, and improvement in mean relative enhancement ratio showed moderate or good correlation, both statistically significant (-0.44≤r≤0.71, p<0.05).

CONCLUSION

O2-enhanced MRI shows potential for more accurate evaluation of postoperative clinical outcome for LVRS candidates than SPECT/CT and can be considered at least as reliable as MDCT.

Three-dimensional airway lumen volumetry: comparison with bronchial wall area and parenchymal densitometry in assessment of airway obstruction in pulmonary emphysema

OBJECTIVES

The purpose of this study was to compare three-dimensional airway lumen volumetry with bronchial wall area and parenchymal densitometry in the assessment of airway obstruction in pulmonary emphysema.

METHODS

56 patients, who were smokers, underwent CT examination and pulmonary function tests (PFTs). For quantitative assessments, the following parameters were computationally calculated: (1) percentage of voxels -950, -960 and -970 HU in the lung (%LAA(-950), %LAA(-960) and %LAA(-970), respectively); (2) percentage of partial bronchi luminal volumes per total luminal volumes (LV(main), main and distal bronchial volume/total luminal volume; LV(lobe), lobar and distal bronchial volume/total luminal volume); and (3) mean wall area percentages of segmental bronchi of the right apical and left apicoposterior segment (WA%(seg)) and of subsegmental bronchi (WA%(sub)) in the upper lobes. These parameters were correlated with PFTs and statistically compared between a chronic obstructive pulmonary disease (COPD) group [forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC)<70] and a non-COPD group.

RESULTS

FEV1, maximum mid-expiratory flow rate and forced expiratory flow at 25% vital capacity had significant correlation with LV(main) (r>0.53, p<0.0001), LV(lobe) (r>0.52, p<0.0001), WA%(seg) (|r|>0.29, p<0.05) and WA%(sub) (|r|>0.31, p<0.05). FEV1/FVC had significant correlation with all parameters (0.27<|r|<0.52, p<0.05). LV(main) and LV(lobe) and WA%(seg) and WA%(sub) were significantly different between the two groups (LV(main) and LV(lobe); p<0.0001, WA%(seg) and WA%(sub); p<0.05).

CONCLUSIONS

Bronchial luminal volumetric assessment better reflected the airflow limitation parameters.

ADVANCES IN KNOWLEDGE

Bronchial luminal volumetric assessment can potentially be used to gauge airflow limitation in pulmonary emphysema.

Pulmonary magnetic resonance imaging for airway diseases

Pulmonary magnetic resonance (MR) imaging has been put forward as a new research and diagnostic tool mainly to overcome the limitations of computed tomography and nuclear medicine studies. However, pulmonary MR imaging has been difficult to use because of inherently low proton density, a multitude of air-tissue interfaces, which create significant magnetic field distortions and are commonly referred to as susceptibility artifacts; diminishing signal in the lung; and respiratory and/or cardiac motion artifacts. To overcome these drawbacks of pulmonary MR imaging, technical advances made during the last decade in sequencing, scanner and coil, adaptation of parallel imaging techniques, and utilization of contrast media have been reported as being useful for functional and morphologic assessment of various pulmonary diseases including airway diseases. This review article covers (1) pulmonary MR techniques for morphologic and functional assessment of airway diseases, and (2) pulmonary MR imaging for cystic fibrosis, asthma, and chronic obstructive pulmonary disease. Pulmonary MR imaging provides not only morphology-related but also pulmonary function-related information. It has the potential to replace nuclear medicine studies for the identification of regional pulmonary function and may perform a complementary role in airway disease assessment instead of nuclear medicine study. We believe that the findings of further basic studies as well as clinical applications of this new technique will validate the real significance of pulmonary MR imaging for the future of airway disease assessment and its usefulness for diagnostic radiology and pulmonary medicine.

Quantitative bronchial luminal volumetric assessment of pulmonary function loss by thin-section MDCT in pulmonary emphysema patients

OBJECTIVES

To determine the capability of quantitative bronchial luminal volume to assess pulmonary function loss and disease severity in pulmonary emphysema patients.

METHODS

Thirty-seven smokers (mean age, 68.1 years) underwent CT examinations and pulmonary function tests. For the quantitative assessment, luminal voxels of trachea and bronchi were computationally counted and the ratio of the following luminal voxels to all luminal voxels was obtained: (1) the lobe bronchi and the peripheral bronchi (Ratio(lobe)), and (2) the main bronchi and the peripheral bronchi (Ratio(main)). To determine the capability of these assessments to predict pulmonary function loss, these ratios were correlated with pulmonary function tests. To determine the capability for predicting disease severity, these ratios were compared between clinical groups.

RESULTS

These ratios were no significant correlated with vital capacity and forced vital capacity (FVC) (p > 0.05), however significantly correlated with forced expiratory volume in 1s (FEV1) (Ratio(lobe): r = 0.61, p < 0.0001, Ratio(main): r = 0.58, p < 0.0005) and FEV1/FVC (Ratio(lobe): r = 0.36, p < 0.05, Ratio(main): r = 0.33, p < 0.05). The Ratio(lobe) of smokers without COPD was significantly different from those of moderate COPD and severe or very severe COPD (p < 0.05), while that of mild COPD was significantly different from that of severe or very severe COPD (p < 0.01). The Ratio(main) of severe or very severe COPD patients was significantly different from those of other groups (p < 0.05).

CONCLUSIONS

Quantitative bronchial luminal volumes were reflected the airflow limitation parameters and was corresponded to clinical groups in emphysema patients.

Analysis of signal dynamics in oxygen-enhanced magnetic resonance imaging

OBJECTIVES

Oxygen-enhanced MRI (O2-MRI) is frequently based on a block paradigm consisting of a series of consecutive T1-weighted scans acquired during alternating blocks with inhalation of room air and of pure oxygen. This design results in a complex signal-time course for each pixel, which displays the oxygen wash-in and wash-out processes and provides spatially resolved information about the lung function. The purpose of the present study was to optimize the signal-time-course analysis to extract (pixelwise) the maximum amount of information from the acquired data, and to introduce an appropriate cross-correlation approach for data sets containing the oxygen wash-in and wash-out periods.

MATERIALS AND METHODS

O2-MRI data of 11 healthy volunteers were acquired with a multislice inversion-recovery single-shot turbo-spin-echo sequence at 1.5 Tesla; lung and spleen were manually segmented on all 44 acquired slices. Six different model functions were pixelwise fitted to the data and compared using the Akaike information criterion. Four different reference functions were compared for cross-correlation analysis.

RESULTS

The optimal model function is a piecewise exponential function (median enhancement in lung/spleen: 16.3%/14.8%) with different time constants for wash-in (29.4 seconds/72.7 seconds) and wash-out (25.1 seconds/29.6 seconds). As a new parameter, it contains the delay between switching the gas supply and the onset of the signal change (4.8 seconds/24.5 seconds). Optimal cross-correlation results were obtained with a piecewise exponential reference function, which was temporally shifted to maximize the correlation, yielding median correlation coefficients of 0.694 and 0.878, median time delays of 7.5 seconds and 38.6 seconds, and median fractions of oxygen-activated pixels of 83.6% and 92.2% in the lung and the spleen, respectively.

CONCLUSIONS

It was demonstrated that the pixelwise assessment of O2-MRI data are optimally performed with piecewise exponential functions. Cross-correlation analysis with a piecewise exponential reference function results in significantly higher fractions of oxygen-activated pixels than with rectangular functions.

Quantitative and qualitative assessments of lung destruction and pulmonary functional loss from reduced-dose thin-section CT in pulmonary emphysema patients

RATIONALE AND OBJECTIVES

Academic and clinical interest in reducing radiation from computed tomography (CT) examinations has increased, and the purpose of this study was to determine the capabilities of reduced-dose multidetector-row CT (MDCT) in assessing lung destruction and pulmonary functional loss in pulmonary emphysema patients.

MATERIALS AND METHODS

Twenty-five consecutive smokers (15 men and 10 women; mean age 67.9 years; age range 49-86 years) underwent MDCT examinations using two different effective tube currents (standard-dose protocol [150 mAs] and reduced-dose protocol [50 mAs]). For quantitative and qualitative assessments of lung destruction in each subject, percentage of low attenuation emphysematous destruction areas (%LAAs) were computationally calculated, and visual emphysema scores (ESs) were determined for both protocols. To determine the capabilities for quantitative and qualitative assessments of lung destruction by using reduced-dose protocol, %LAAs and ESs of both protocols were compared statistically. To compare the capabilities for quantitative and qualitative assessments of pulmonary functional loss, %LAAs and ESs of both protocols were correlated with forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC).

RESULTS

%LAAs and ESs had significant correlations between both protocols (%LAAs: r = 0.95, P < .001; ESs: r = 0.97, P < .001). The limits of agreement of %LAAs were -1.8 + or - 9.2%. The agreement of ESs between both protocols was substantial (kappa = 0.70). %LAAs and ESs of both protocols had significant correlations with FEV1/FVC (%LAAs of 150 mAs: r = -0.49, P < .05; %LAAs of 50 mAs: r = -0.44, P < .05; ESs of 150 mAs: r = -0.67, P < .001; ESs of 50 mAs: r = -0.66, P < .001).

CONCLUSION

Reduced-dose MDCT had a potential of substitution for standard-dose MDCT on the both assessments in pulmonary emphysema patients.

Oxygen-enhanced MRI vs. quantitatively assessed thin-section CT: pulmonary functional loss assessment and clinical stage classification of asthmatics

PURPOSE

The purpose of this study was to prospectively compare the efficacy of oxygen-enhanced MR imaging (O(2)-enhanced MRI) and CT for pulmonary functional loss assessment and clinical stage classification of asthmatics.

MATERIALS AND METHODS

O(2)-enhanced MRI, CT and %FEV(1) measurement were used 34 consecutive asthmatics classified into four stages ('Mild Intermittent [n=7]', 'Mild Persistent [n=8], 'Moderate Persistent [n=14]' and 'Severe Persistent [n=5]'). Relative enhancement ratio maps for every subject were generated, and determine mean relative enhancement ratios (MRERs). Mean lung density (MLD) and the airway wall area (WA) corrected by body surface area (WA/BSA) were also measured on CT. To compare the efficacy of the two methods for pulmonary functional loss assessment, all indexes were correlated with %FEV(1). To determine the efficacy of the two methods for clinical stage classification, all parameters for the four clinical stages were statistically compared.

RESULTS

%FEV(1) showed fair or moderate correlation with all parameters (0.15≤r(2)≤0.30, p<0.05). WA, WA/BSA and MRER of the 'Severe Persistent' group were significantly larger than those of 'Mild Intermittent' and 'Mild Persistent' groups (p<0.05), and MRER of the 'Moderate Persistent' group significantly lower than that of the 'Mild Intermittent' group (p<0.05).

CONCLUSION

O(2)-enhanced MRI is as effective as CT for pulmonary functional loss assessment and clinical stage classification of asthmatics.

Preoperative evaluation for thoracic surgery

The goal of the preoperative evaluation for thoracic surgery is to assess and implement measures to decrease perioperative complications and prepare high-risk patients for surgery. Major respiratory complications, such as atelectasis, pneumonia, and respiratory failure, occur in 15% to 20% of patients and account for most of the 3% to 4% mortality rate. Development of pulmonary complications has been associated with higher postoperative mortality rates. Strategies aimed at preventing postoperative difficulties have the potential to reduce morbidity and mortality, decrease hospital stay, and improve resource use. One lung ventilation leads to a significant derangement of gas exchange, and hypoxemia can develop due to increased intrapulmonary shunting. Recent advances in anesthetic management, monitoring devices, improved lung isolation techniques, and improved critical care management have increased the number of patients who were previously considered inoperable. In addition, there is a growing tendency to offer surgery to patients with significant lung function impairment; hence a higher incidence of intraoperative gas-exchange abnormalities can be expected. The anesthesiologist must also consider the risks of denying or postponing a potentially curative operation in patients with lung cancer. Detailed consideration of the information provided by preoperative testing is essential to successful outcomes following thoracic surgery.

Oxygen-enhanced magnetic resonance imaging: influence of different gas delivery methods on the T1-changes of the lungs

OBJECTIVE

The clinical feasibility of oxygen-enhanced magnetic resonance imaging (MRI) of the lung may benefit from the use of a simple gas delivery method. In this study, the oxygen-induced T1 change of the lung obtained using a closed O(2) delivery system was compared with that obtained by a conventional nontight face mask.

MATERIAL AND METHODS

Twenty-three healthy subjects (15 men, 8 women, mean age = 25 years, age range = 20-35 years) underwent oxygen-enhanced MRI of the lung using a closed O(2) delivery system composed by a tightly fitting face mask and a 60-L reservoir bag (equipment type A: n = 13, 9 men, 4 women, mean age = 24.4 years, age range = 20-32 years), or a clinically available nontight face mask (equipment type B: n = 10; 6 men, 4 women, mean age = 25.8 years, age range = 20-35 years). The effect of 100%-oxygen inhalation was assessed using a Snapshot FLASH T1-mapping technique (repetition time/echo time = 1.5-1.6/0.56 milliseconds; matrix = 128 x 90; acquisition time = 3.3-3.7 seconds; slice thickness = 15-20 mm; number of images = 40). By nonlinear curve fitting, the mean T1 values of the left and right lung at room air and 100%-oxygen ventilation were calculated (T1(room air, right); T1(oxygen, right); T1(room air, left); T1(oxygen, left)). The average T1 differences (DeltaT1 = T1(room air) - T1(oxygen)) of the 2 volunteer groups were compared (Wilcoxon signed rank test, Mann-Whitney U test).

RESULTS

The mean T1 values obtained using the 2 respiratory equipments at room air or oxygen ventilation were not significantly different (A vs. B at room air ventilation: P = 0.85 for the right lung, P = 0.27 for the left lung; A vs. B at oxygen ventilation: P = 0.55 for the left lung, P = 0.29 for the right lung). With both systems, the mean T1 values decreased significantly after oxygen inhalation (P = 0.03-0.0002). For both lungs, the DeltaT1 obtained using the equipment type A was statistically equivalent to that obtained using the equipment type B: DeltaT1A, right = 96 +/- 19 milliseconds versus DeltaT1B, right = 97 +/- 34 milliseconds (P = 0.82); DeltaT1A, left = 74 +/- 47 milliseconds versus DeltaT1B, left = 68 +/- 63 milliseconds (P = 0.85).

CONCLUSION

Gas delivery in oxygen-enhanced MRI of the lung can be performed with a clinically available standard face mask, without the need for closed sophisticated equipments.

Functional MR imaging of the lung

Recent development of MR techniques has overcome many problems, such as susceptibility artifacts or motion artifact, allowing both static and dynamic MR lung imaging and providing quantitative information of pulmonary function, including perfusion, ventilation, and respiratory motion. Dynamic contrast-enhanced MR perfusion imaging is suitable for the evaluation of angiogenesis of pulmonary solitary nodules. (129)Xe MR imaging is potentially a robust technique for the evaluation of various pulmonary function and may replace (3)He. The information provided by these new MR imaging methods is proving useful in research and in clinical applications in various lung diseases.

Navigator-triggered oxygen-enhanced MRI with simultaneous cardiac and respiratory synchronization for the assessment of interstitial lung disease

PURPOSE

To evaluate an optimized method for oxygen-enhanced MRI of the lung, using simultaneous electrocardiograph (ECG) and navigator triggering. To correlate oxygen-enhanced MRI with lung function tests assessing alveolar-capillary gas exchange.

MATERIALS AND METHODS

A total of 12 healthy volunteers (aged 20-32 years) and 10 patients (aged 37-87 years) with interstitial lung diseases (ILD) underwent oxygen-enhanced MRI and pulmonary functional tests (PFTs) assessing alveolar-capillary gas exchange. The paradigm room-air-oxygen-room-air was acquired with a nonselective inversion-recovery half-Fourier single-shot turbo spin-echo sequence (inversion time = 1200 msec; acquisition time = 134.5 msec; slice thickness = 20 mm; matrix size = 128 x 128), using simultaneous double triggering (navigator plus ECG trigger). Cross-correlation was performed in regions of interest (ROIs) encompassing both lungs. The number of oxygen-activated pixels over the total number of pixels in the ROIs (OAP%) of volunteers and patients was compared. OAP%s were correlated with PFTs.

RESULTS

The mean OAP% of patients was significantly lower than that of volunteers (36.7 vs. 81.7, P = 0.001). OAP% correlated with the transfer lung factor for carbon monoxide (Tlco) (r = 0.64; P = 0.002), the transfer coefficient (Kco) (r = 0.75; P = 0.001), the arterial partial pressure (r = 0.77; P < 0.001), and the saturation (r = 0.70; P < 0.001) of oxygen.

CONCLUSION

Navigator-triggered oxygen-enhanced MRI of the lung may have a potential role in the quantitative assessment of lung function in ILD.

Oxygen-enhanced magnetic resonance imaging versus computed tomography: multicenter study for clinical stage classification of smoking-related chronic obstructive pulmonary disease

RATIONALE

Oxygen-enhanced magnetic resonance imaging (MRI) has been proposed as a useful tool for assessing regional morphological and functional changes in chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To prospectively and directly compare the efficacy of O(2)-enhanced MRI and quantitative computed tomography (CT) for smoking-related pulmonary functional loss assessment and clinical stage classification of smoking-related COPD.

METHODS

One hundred sixty smokers were classified into four age- and gender-matched groups by using the GOLD criteria for smokers: Smokers without COPD (n = 40), Mild COPD (n = 40), Moderate COPD (n = 40), and Severe or Very Severe COPD (n = 40). All smokers underwent O(2)-enhanced MRI, multidetector-row CT, and pulmonary function test. Mean relative enhancement ratio on O(2)-enhanced MRI and CT-based functional lung volume (FLV) on quantitative CT were calculated. To compare the efficacy of O(2)-enhanced MRI and quantitative CT for pulmonary functional loss assessment, both indexes were correlated with pulmonary functional parameters. To determine the efficacy of two methods for clinical stage classification, the four clinical groups' mean relative enhancement ratio and CT-based FLV were statistically compared.

MEASUREMENTS AND MAIN RESULTS

Correlations of both indexes with pulmonary functional parameters were significant (P < 0.0001). Pulmonary functional parameters and mean relative enhancement ratio for the four clinical groups showed significant differences (P < 0.05). CT-based FLVs of smokers without COPD and mild COPD were significantly different from those for moderate COPD and severe or very severe COPD (P < 0.05).

CONCLUSIONS

O(2)-enhanced MRI is effective for pulmonary functional loss assessment and clinical stage classification of smoking-related COPD and quantitative CT.

Dynamic oxygen-enhanced MRI versus quantitative CT: pulmonary functional loss assessment and clinical stage classification of smoking-related COPD

OBJECTIVE

The purpose of the present study is to prospectively compare the capability of dynamic oxygen-enhanced MRI and quantitative CT for pulmonary functional loss assessment and clinical stage classification of smoking-related chronic obstructive pulmonary disease (COPD).

SUBJECTS AND METHODS

Ten nonsmoking and 61 consecutive smoking-related COPD subjects underwent dynamic oxygen-enhanced MRI, CT, and pulmonary function tests. COPD subjects were classified into four clinical stages on the basis of the ATS-ERS guidelines. Wash-in time and relative enhancement ratio maps were generated by pixel-by-pixel analyses. Mean wash-in time and relative enhancement ratio were determined as averages of region of interest (ROI) measurements. CT-based functional lung volumes were measured on quantitative CT using the density-masked CT technique. For comparison of assessment capability for smoking-related functional loss, the three parameters were correlated with the percentage predicted forced expiratory volume in 1 second (%FEV1) and the percentage predicted diffusing capacity of the lung for carbon monoxide corrected for alveolar volume (%DL(CO)/VA). To determine the clinical stage classification capability, these parameters were statistically compared for nonsmoking subjects and all clinical stages of smoking-related COPD subjects.

RESULTS

Correlation between mean wash-in time and %FEV1 (r = -0.74, p < 0.0001) and between mean relative enhancement ratio and %DL(CO)/VA (r = 0.66, p < 0.0001) was better than that between CT-based functional lung volume and either %FEV1 (r = 0.61, p < 0.0001) or %DL(CO)/VA (r = 0.56, p < 0.0001). Mean wash-in time showed a significant difference between nonsmoking and smoking-related COPD subjects at all clinical stages (p < 0.05).

CONCLUSION

Dynamic oxygen-enhanced MRI has potential for pulmonary functional loss assessment and clinical stage classification of smoking-related COPD as does quantitative CT.

Basics concepts and clinical applications of oxygen-enhanced MR imaging

Oxygen-enhanced MR imaging is a new technique, and its physiological significance has not yet been fully elucidated. This review article covers (1) the theory of oxygen enhancement and its relationship with respiratory physiology; (2) design for oxygen-enhanced MR imaging sequencing; (3) a basic study of oxygen-enhanced MR imaging in animal models and humans; (4) a clinical study of oxygen-enhanced MR imaging; and (5) a comparison of advantages and disadvantages of this technique with those of hyperpolarized noble gas MR ventilation imaging. Oxygen-enhanced MR imaging provides not only the ventilation-related, but also respiration-related information. Oxygen-enhanced MR imaging has the potential to replace nuclear medicine studies for the identification of regional pulmonary function, and many investigators are now attempting to adapt this technique for routine clinical studies. We believe that further basic studies as well as clinical applications of this new technique will define the real significance of oxygen-enhanced MR imaging for the future of pulmonary functional imaging and its usefulness for diagnostic radiology and pulmonary medicine.

Physiologic evaluation of the patient with lung cancer being considered for resectional surgery: ACCP evidenced-based clinical practice guidelines (2nd edition)

BACKGROUND

This section of the guidelines is intended to provide an evidence-based approach to the preoperative physiologic assessment of a patient being considered for surgical resection of lung cancer.

METHODS

Current guidelines and medical literature applicable to this issue were identified by computerized search and evaluated using standardized methods. Recommendations were framed using the approach described by the Health and Science Policy Committee.

RESULTS

The preoperative physiologic assessment should begin with a cardiovascular evaluation and spirometry to measure the FEV(1). If diffuse parenchymal lung disease is evident on radiographic studies or if there is dyspnea on exertion that is clinically out of proportion to the FEV(1), the diffusing capacity of the lung for carbon monoxide (Dlco) should also be measured. In patients with either an FEV(1) or Dlco < 80% predicted, the likely postoperative pulmonary reserve should be estimated by either the perfusion scan method for pneumonectomy or the anatomic method, based on counting the number of segments to be removed, for lobectomy. An estimated postoperative FEV(1) or Dlco < 40% predicted indicates an increased risk for perioperative complications, including death, from a standard lung cancer resection (lobectomy or greater removal of lung tissue). Cardiopulmonary exercise testing (CPET) to measure maximal oxygen consumption (Vo(2)max) should be performed to further define the perioperative risk of surgery; a Vo(2)max of < 15 mL/kg/min indicates an increased risk of perioperative complications. Alternative types of exercise testing, such as stair climbing, the shuttle walk, and the 6-min walk, should be considered if CPET is not available. Although often not performed in a standardized manner, patients who cannot climb one flight of stairs are expected to have a Vo(2)max of < 10 mL/kg/min. Data on the shuttle walk and 6-min walk are limited, but patients who cannot complete 25 shuttles on two occasions will likely have a Vo(2)max of < 10 mL/kg/min. Desaturation during an exercise test has not clearly been associated with an increased risk for perioperative complications. Lung volume reduction surgery (LVRS) improves survival in selected patients with severe emphysema. Accumulating experience suggests that patients with extremely poor lung function who are deemed inoperable by conventional criteria might tolerate combined LVRS and curative-intent resection of lung cancer with an acceptable mortality rate and good postoperative outcomes. Combining LVRS and lung cancer resection should be considered in patients with a cancer in an area of upper lobe emphysema, an FEV(1) of > 20% predicted, and a Dlco of > 20% predicted.

CONCLUSIONS

A careful preoperative physiologic assessment will be useful to identify those patients who are at increased risk with standard lung cancer resection and to enable an informed decision by the patient about the appropriate therapeutic approach to treating their lung cancer. This preoperative risk assessment must be placed in the context that surgery for early-stage lung cancer is the most effective currently available treatment for this disease.

Postoperative Lung Function in Lung Cancer Patients: Comparative Analysis of Predictive Capability of MRI, CT, and SPECT

OBJECTIVE

The purpose of this study was to prospectively compare the utility of dynamic contrast-enhanced perfusion MRI in the prediction of postoperative lung function in patients with lung cancer with the utility of quantitative and qualitative assessment of CT and perfusion SPECT.

SUBJECTS AND METHODS

One hundred fifty lung cancer patients (87 men, 63 women) underwent dynamic perfusion MRI, MDCT, perfusion SPECT, and measurement of preoperative and postoperative forced expiratory volume in the first second of expiration (FEV1) expressed as percentage of predicted value. Postoperative FEV1 was predicted with dynamic perfusion MRI by semiquantitative assessment of the perfusion of whole lungs and resected segments of lungs, with quantitative assessment of functional lung volume on CT with commercially available software, with qualitative assessment of CT on the basis of the number of segments of total and resected lung, and with perfusion SPECT by assessment of uptake of microaggregated albumin particles in whole lungs and resected segments of lungs. Correlation and limits of agreement between actual and predicted postoperative FEV1 values were statistically evaluated.

RESULTS

Actual postoperative FEV1 had stronger correlation with postoperative FEV1 predicted from perfusion MRI (r = 0.87, p < 0.0001) and quantitative CT (r = 0.88, p < 0.0001) than with postoperative FEV1 predicted from qualitative CT (r = 0.83, p < 0.0001) and perfusion SPECT (r = 0.83, p < 0.0001). The limits of agreement between the actual postoperative FEV1 and postoperative FEV1 predicted from perfusion MRI (5.3% +/- 11.8% [mean +/- 2 SD]) were smaller than the values for postoperative FEV1 predicted from qualitative CT (6.8% +/- 14.4%) and perfusion SPECT (5.1% +/- 14.0%) and was almost equal to the value for postoperative FEV1 predicted from quantitative CT (5.0% +/- 11.6%).

CONCLUSION

Dynamic perfusion MRI is more accurate in prediction of the postoperative lung function of patients with lung cancer than are qualitative CT and perfusion SPECT and may be at least as accurate as quantitative CT.

Coregistered ventilation and perfusion SPECT using krypton-81m and Tc-99m-labeled macroaggregated albumin with multislice CT utility for prediction of postoperative lung function in non-small cell lung cancer patients

RATIONALE AND OBJECTIVE

Co-registered SPECT and CT imaging (SPECT-CT) has potential for more precise evaluation of regional pulmonary function and may be useful for prediction of postoperative lung function in non-small cell lung cancer (NSCLC) patients. The purpose of the present study was to prospectively assess the capability of co-registered SPECT-CT using krypton-81m (Kr-81m) and technetium-99m-labeled macroaggregated albumin (Tc-99m MAA) for prediction of postoperative lung function of NSCLC patients compared with SPECT and planar imaging.

MATERIALS AND METHODS

Sixty consecutive patients considered candidates for lung resection underwent 16-slice CT, ventilation and perfusion scintigraphy with SPECT examinations, and preoperative and postoperative measurement of FEV(1)%. In each subject, SPECT and CT data were automatically fused by using commercially available software. Each postoperative FEV(1)% value was predicted from uptakes of Kr-81m and Tc-99m MAA within total and resected lungs. Then, reproducibility coefficients and the limits of agreement between actual and each predicted postoperative lung function were statistically assessed.

RESULTS

Reproducibility coefficients of SPECT-CT (Kr-81m: 5.1%, Tc-99m MAA: 5.2%) were smaller than those of SPECT and planar image using Kr-81m (SPECT: 7.4%, planar image: 12.1%) and using Tc-99m MAA (SPECT: 7.2%, planar image: 11.8%). The limits of agreement for SPECT-CT (Kr-81m: 3.3 +/- 10.5%, Tc-99m MAA: 5.4 +/- 11.0%) were also smaller than that of SPECT and planar image and small enough for clinical purposes.

CONCLUSIONS

Co-registered SPECT-CT using Kr-81m and Tc-99m MAA was able to more reproducibly and accurately predict postoperative lung function compared with SPECT and planar imaging.