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Verma M, Jagia P, Roy A, Chaturvedi PK, Kumar S, Seth S, Singh V, Ojha V, Pandey NN. Lung water estimation on cardiac magnetic resonance imaging for predicting adverse cardiovascular outcomes in patients with heart failure. Br J Radiol 2023; 96:20220723. [PMID: 37001041 PMCID: PMC10230384 DOI: 10.1259/bjr.20220723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 03/01/2023] [Accepted: 03/13/2023] [Indexed: 04/03/2023] Open
Abstract
OBJECTIVES Pulmonary congestion is a central feature of heart failure (HF) seen in acute decompensated state as well as in chronic stable disease. The present study sought to determine whether simplified cardiac magnetic resonance imaging (CMR)-derived lung water density (LWD) measurement has prognostic relevance in predicting adverse cardiovascular outcomes in patients with HF and left ventricular ejection fraction (LVEF)<50%. METHODS Eighty consecutive patients referred for CMR with HF and LVEF<50% along with 22 healthy age- and sex-matched controls were prospectively recruited. LWD was the lung-to-liver signal intensity ratio multiplied by 70% (estimated hepatic water density). The primary endpoint was composite of all-cause mortality or HF-related hospitalization within 6 months from CMR. RESULTS The mean LWD was significantly higher in HF patients compared to healthy controls (19.78 ± 6.1 vs 13.6 ± 2.3; p < 0.001). The mean LWD was significantly different among patients with NYHA class I/II and NYHA class III/IV (17.88 ± 4.8 vs 21.77 ± 1.08; p = 0.004). At 6 months, the primary endpoint was reached in 12 (15%) patients. Patients with "wet lungs" (LWD > 18.1%) had higher incidence of adverse cardiovascular outcomes compared to patients with "dry lungs". LWD was an independent predictor of adverse cardiovascular outcomes in multivariable analysis. At the optimal cut-off of LWD > 23.38%, the sensitivity and specificity were 91.67 and 91.18%, respectively, to predict adverse cardiovascular outcomes. CONCLUSION LWD on CMR is independently associated with increased risk of mortality and HF-related hospitalization in HF patients with LVEF<50%. ADVANCES IN KNOWLEDGE Non-invasive quantitative estimation of LWD on CMR can improve risk stratification and guide management in HF patients.
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Affiliation(s)
- Mansi Verma
- Department of Cardiovascular Radiology & Endovascular Interventions, All India Institute of Medical Sciences, New Delhi, India
| | - Priya Jagia
- Department of Cardiovascular Radiology & Endovascular Interventions, All India Institute of Medical Sciences, New Delhi, India
| | - Ambuj Roy
- Department of Cardiology, All India Institute of Medical Sciences, New Delhi, India
| | | | - Sanjeev Kumar
- Department of Cardiovascular Radiology & Endovascular Interventions, All India Institute of Medical Sciences, New Delhi, India
| | - Sandeep Seth
- Department of Cardiology, All India Institute of Medical Sciences, New Delhi, India
| | - Vishwajeet Singh
- Department of Geriatric Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Vineeta Ojha
- Department of Cardiovascular Radiology & Endovascular Interventions, All India Institute of Medical Sciences, New Delhi, India
| | - Niraj Nirmal Pandey
- Department of Cardiovascular Radiology & Endovascular Interventions, All India Institute of Medical Sciences, New Delhi, India
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Thompson RB, Chow K, Pagano JJ, Sekowski V, Michelakis ED, Tymchak W, Haykowsky MJ, Ezekowitz JA, Oudit GY, Dyck JRB, Kaul P, Savu A, Paterson DI. Quantification of lung water in heart failure using cardiovascular magnetic resonance imaging. J Cardiovasc Magn Reson 2019; 21:58. [PMID: 31511018 PMCID: PMC6739968 DOI: 10.1186/s12968-019-0567-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 07/23/2019] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Pulmonary edema is a cardinal feature of heart failure but no quantitative tests are available in clinical practice. The goals of this study were to develop a simple cardiovascular magnetic resonance (CMR) approach for lung water quantification, to correlate CMR derived lung water with intra-cardiac pressures and to determine its prognostic significance. METHODS Lung water density (LWD, %) was measured using a widely available single-shot fast spin-echo acquisition in two study cohorts. Validation Cohort: LWD was compared to left ventricular end-diastolic pressure or pulmonary capillary wedge pressure in 19 patients with heart failure undergoing cardiac catheterization. Prospective Cohort: LWD was measured in 256 subjects, including 121 with heart failure, 82 at-risk for heart failure and 53 healthy controls. Clinical outcomes were evaluated up to 1 year. RESULTS Within the validation cohort, CMR LWD correlated to invasively measured left-sided filling pressures (R = 0.8, p < 0.05). In the prospective cohort, mean LWD was 16.6 ± 2.1% in controls, 17.9 ± 3.0% in patients at-risk and 19.3 ± 5.4% in patients with heart failure, p < 0.001. In patients with or at-risk for heart failure, LWD > 20.8% (mean + 2 standard deviations of healthy controls) was an independent predictor of death, hospitalization or emergency department visit within 1 year, hazard ratio 2.4 (1.1-5.1, p = 0.03). CONCLUSIONS In patients with heart failure, increased CMR-derived lung water is associated with increased intra-cardiac filling pressures, and predicts 1 year outcomes. LWD could be incorporated in standard CMR scans.
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Affiliation(s)
- Richard B. Thompson
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
| | - Kelvin Chow
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
| | - Joseph J. Pagano
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
| | - Viktor Sekowski
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
| | - Evangelos D. Michelakis
- Division of Cardiology, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Wayne Tymchak
- Division of Cardiology, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Mark J. Haykowsky
- College of Nursing and Health Innovation, The University of Texas Arlington, Arlington, TX USA
| | - Justin A. Ezekowitz
- Division of Cardiology, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
- Canadian Vigour Centre, University of Alberta, Edmonton, Canada
| | - Gavin Y. Oudit
- Division of Cardiology, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Jason R. B. Dyck
- Department of Pediatrics, University of Alberta, Edmonton, Canada
| | - Padma Kaul
- Division of Cardiology, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Anamaria Savu
- Canadian Vigour Centre, University of Alberta, Edmonton, Canada
| | - D. Ian Paterson
- Division of Cardiology, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
- University of Alberta Hospital, MacKenzie Health Sciences Centre, 8440–112 street, 2C2.43 Walter C, Edmonton, Alberta T6G2B7 Canada
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Jagadale BN, Udupa JK, Tong Y, Wu C, McDonough J, Torigian DA, Campbell RM. Lung Parenchymal Analysis on Dynamic MRI in Thoracic Insufficiency Syndrome to Assess Changes Following Surgical Intervention. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2018; 10575. [PMID: 30899130 DOI: 10.1117/12.2295012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
General surgeons, orthopedists, and pulmonologists individually treat patients with thoracic insufficiency syndrome (TIS). The benefits of growth-sparing procedures such as Vertical Expandable Prosthetic Titanium Rib (VEPTR)insertionfor treating patients with TIS have been demonstrated. However, at present there is no objective assessment metricto examine different thoracic structural components individually as to their roles in the syndrome, in contributing to dynamics and function, and in influencing treatment outcome. Using thoracic dynamic MRI (dMRI), we have been developing a methodology to overcome this problem. In this paper, we extend this methodology from our previous structural analysis approaches to examining lung tissue properties. We process the T2-weighted dMRI images through a series of steps involving 4D image construction of the acquired dMRI images, intensity non-uniformity correction and standardization of the 4D image, lung segmentation, and estimation of the parameters describing lung tissue intensity distributions in the 4D image. Based on pre- and post-operative dMRI data sets from 25 TIS patients (predominantly neuromuscular and congenital conditions), we demonstrate how lung tissue can be characterized by the estimated distribution parameters. Our results show that standardized T2-weighted image intensity values decrease from the pre- to post-operative condition, likely reflecting improved lung aeration post-operatively. In both pre- and post-operative conditions, the intensity values decrease also from end-expiration to end-inspiration, supporting the basic premise of our results.
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Affiliation(s)
- Basavaraj N Jagadale
- Medical Image Processing Group, Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104,United States
| | - Jayaram K Udupa
- Medical Image Processing Group, Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104,United States
| | - Yubing Tong
- Medical Image Processing Group, Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104,United States
| | - Caiyun Wu
- Medical Image Processing Group, Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104,United States
| | - Joseph McDonough
- Center for Thoracic Insufficiency Syndrome, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, United States
| | - Drew A Torigian
- Center for Thoracic Insufficiency Syndrome, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, United States
| | - Robert M Campbell
- Center for Thoracic Insufficiency Syndrome, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, United States
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Owrangi AM, Wang JX, Wheatley A, McCormack DG, Parraga G. Quantitative 1H and hyperpolarized 3He magnetic resonance imaging: Comparison in chronic obstructive pulmonary disease and healthy never-smokers. Eur J Radiol 2014; 83:64-72. [DOI: 10.1016/j.ejrad.2012.02.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 02/27/2012] [Indexed: 10/28/2022]
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Weick S, Breuer FA, Ehses P, Völker M, Hintze C, Biederer J, Jakob PM. DC-gated high resolution three-dimensional lung imaging during free-breathing. J Magn Reson Imaging 2012; 37:727-32. [PMID: 22987283 DOI: 10.1002/jmri.23798] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 08/02/2012] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To use the acquisition of the k-space center signal (DC signal) implemented into a Cartesian three-dimensional (3D) FLASH sequence for retrospective respiratory self-gating and, thus, for the examination of the whole human lung in high spatial resolution during free breathing. MATERIALS AND METHODS Volunteer as well as patient measurements were performed under free breathing conditions. The DC signal is acquired after the actual image data acquisition within each excitation of a 3D FLASH sequence. The DC signal is then used to track respiratory motion for retrospective respiratory gating. RESULTS It is shown that the acquisition of the DC signal after the imaging module can be used in a 3D FLASH sequence to extract respiratory motion information for retrospective respiratory self-gating and allows for shorter echo times (TE) and therefore increased lung parenchyma SNR. CONCLUSION The acquisition of the DC signal after image signal acquisition allows successful retrospective gating, enabling the reconstruction of high resolution images of the whole human lung under free breathing conditions.
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Affiliation(s)
- Stefan Weick
- Department of Experimental Physics 5, University of Wuerzburg, Germany.
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Molinari F, Eichinger M, Risse F, Plathow C, Puderbach M, Ley S, Herth F, Bonomo L, Kauczor HU, Fink C. Navigator-triggered oxygen-enhanced MRI with simultaneous cardiac and respiratory synchronization for the assessment of interstitial lung disease. J Magn Reson Imaging 2008; 26:1523-9. [PMID: 17968900 DOI: 10.1002/jmri.21043] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
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.
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Affiliation(s)
- Francesco Molinari
- Department of Bioimaging and Radiological Sciences, Catholic University of Rome, Rome, Italy
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Bankier AA, Storey P, Mai VM, Edelman RR, Chen Q. Gravity-dependent signal gradients on MR images of the lung in supine and prone positions: a comparison with isogravitational signal variability. J Magn Reson Imaging 2006; 23:115-22. [PMID: 16400636 DOI: 10.1002/jmri.20478] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To investigate the tendency of proton MR signal intensity (SI) gradients to be steeper in the supine than in the prone body position, and to quantify the relation between gravity-related and isogravitational changes of SI on proton MR images of the lung. MATERIALS AND METHODS In eight healthy volunteers, MR images were obtained in the supine and prone positions using a multiple inversion recovery turbo spin-echo (TSE) sequence. The variation in SI along the gravity-dependent direction and within isogravitational planes was measured on a pixel-by-pixel basis. Ratios of slopes were calculated for comparisons among volunteers. Comparisons of ratios were made using Fisher's exact test. Isogravitational variability was compared with the mean SI, the signal-to-noise ratio (SNR), and the image noise. RESULTS The average ratios of slopes showed that the overall SI gradient was steeper in the supine than the prone position, with a substantial difference in the supine/prone ratios between inspiration (1.21) and expiration (1.72). In both the supine and prone positions, gravity-dependent gradients were steeper in expiration than in inspiration (P = 0.001). The SI variability along the gravitational direction was larger than the isogravitational variability. The isogravitational variability in turn was larger than the image noise but smaller than the mean SI of the MR images. CONCLUSION Gravity-dependent gradients in proton MR SI are steeper in the supine than in the prone position. The magnitudes of these gradients were larger than the isogravitational signal variability, showing that MRI is sensitive to gravitationally induced effects.
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Molinari F, Gaudino S, Fink C, Corbo GM, Valente S, Pirronti T, Bonomo L. Simultaneous Cardiac and Respiratory Synchronization in Oxygen-Enhanced Magnetic Resonance Imaging of the Lung Using a Pneumotachograph for Respiratory Monitoring. Invest Radiol 2006; 41:476-85. [PMID: 16625111 DOI: 10.1097/01.rli.0000208240.08299.5d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES We sought to evaluate an optimized method for oxygen-enhanced magnetic resonance imaging of the lung, using electrocardiogram-trigger and a pneumotachograph for simultaneous cardiac and respiratory synchronization. MATERIALS AND METHODS Five series of IR-SSFSE images (echo time = 28.2 milliseconds; inversion time = 1,200 milliseconds) were obtained in 6 volunteers during the ventilation-paradigm room-air/oxygen/room-air: series 1, respiratory-triggered; series 2, cardiac-triggered; series 3, cardiac-triggered and respiratory-synchronized using the signal of the pneumatic belt; series 4, cardiac-triggered and respiratory-synchronized using the external signal of the pneumotachograph; and series 5, not cardiac-triggered and respiratory-synchronized using the signal of the pneumotachograph. Standard deviations of the lung (SI(var)) and diaphragm mismatch (DM) were measured. The relative SI change (DeltaSI) was computed from room-air and oxygen-enhanced images. Parametric maps were obtained from cross-correlation analysis of the ventilation paradigm. Mean correlation coefficients (cc) and the percentage of activated pixels over the lung (Act%) were calculated from these maps. All 5 parameters were compared among the 5 series (Friedman-analysis of variance, Dunn's posthoc test). RESULTS In series 4, DM and SI(var) were significantly lower than in respiratory and cardiac-triggered series (DM = 4.7 vs. 14.3 and 18.4; SI(var) = 4.9 vs. 10 and 11). In the same series cc and Act% also were significantly higher than in series 1 and 2 (cc = 0.86 vs. 0.7 and 0.6; Act% = 71.3 vs. 44.7 and 41.2). DeltaSI was not significantly different among all series. CONCLUSIONS Effective respiratory and cardiac synchronization can be achieved in oxygen-enhanced magnetic resonance imaging of the lung, using a pneumotachograph for real-time targeting of end-expiration.
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Affiliation(s)
- Francesco Molinari
- Department of Radiological Sciences, Catholic University of Rome, Rome, Italy.
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Dietrich O, Losert C, Attenberger U, Reuter C, Fasol U, Peller M, Nikolaou K, Reiser MF, Schoenberg SO. Sauerstoff-MRT der Lunge: Optimierte Berechnung von Differenzbildern. Radiologe 2006; 46:300-2, 304-8. [PMID: 16437238 DOI: 10.1007/s00117-005-1324-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND In oxygen-enhanced lung MRI, difference maps of acquisitions during inhalation of room air and pure oxygen are calculated to assess lung function. The purpose of this study was to analyze how the calculation of these difference maps depends on the delayed signal change after switching the gas supply. METHODS Ten healthy volunteers were examined with an ECG and respiratory-triggered T1-weighting inversion recovery HASTE sequence with parallel imaging. Four blocks with 20 repetitions of up to 6 coronal slices were continuously acquired; in blocks 1 and 3 room air was supplied, in blocks 2 and 4 oxygen. Data were postprocessed, discarding between 0 and 19 repetitions after each change of gas supply before calculating the relative signal difference. RESULTS The averaged relative signal difference increases from 9.4 to 17.4% when the number of discarded acquisitions increases; the ratio of signal difference and spatial standard deviation reaches a maximum at 5-8 discarded acquisitions. CONCLUSIONS An optimized ratio of signal difference and statistical error is found if about 5-8 of 20 respiratory-triggered repetitions are discarded after each change of gas supply for the calculation of difference maps.
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Affiliation(s)
- O Dietrich
- Institut für Klinische Radiologie - Grosshadern, Klinikum der Ludwig-Maximilians-Universität, München.
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Hirsch W, Sorge I, Schlüter A, Eichler G, Wenkel R. Assessment of pulmonary air trapping and obstruction in expiration: an experimental MRI study. Magn Reson Imaging 2005; 23:991-4. [PMID: 16376182 DOI: 10.1016/j.mri.2005.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2004] [Revised: 10/04/2005] [Accepted: 10/04/2005] [Indexed: 11/29/2022]
Abstract
PURPOSE The aim of this experimental study was to evaluate the potential of a simple expiration technique by means of magnetic resonance imaging (MRI) in an animal model to detect pulmonary air-trapping areas after artificial bronchial obstruction. MATERIAL AND METHODS Sixteen pigs were evaluated by means of a modified T1-weighted FLASH with fat saturation in respiratory arrest (TR=4.6 ms, TE=1.8 ms, alpha=10 degrees, S.D.=3-5 mm). A measurement of the signal intensity (SI) in the peripheral lung tissue was made in both inspiration and expiration before and after inhalation of 2 ml of 0.5% acetylcholine to simulate a bronchial obstruction. A final measurement of the lung SI was also made after bronchospasmolytic induction through salbutamol (beta2-mimetic bronchodilator). RESULTS In expiration, a mean SI increase in peripheral lung tissue of about 183% was seen in comparison to inspiration (mean SI increase of 11-32). After inhalation of 0.5% acetylcholine, the expirational signal increase in peripheral lung tissue was only 114% of the original SI. The expirational signal homogeneity decreased after inhalation of acetylcholine. After inhalation of salbutamol, the lung tissue signal elevation in expiration was 193%. CONCLUSION We interpret the low expiratory signal elevation after acetylcholine inhalation as a result of an air-trapped bronchial constriction in certain areas. The simple expiratory technique in an animal model showed that it is suitable to demonstrate obstructive air trapping using MRI.
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Affiliation(s)
- Wolfgang Hirsch
- Department of Diagnostic Radiology, University Hospital Leipzig, D-04317 Leipzig, Germany.
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Dietrich O, Losert C, Attenberger U, Fasol U, Peller M, Nikolaou K, Reiser MF, Schoenberg SO. Fast oxygen-enhanced multislice imaging of the lung using parallel acquisition techniques. Magn Reson Med 2005; 53:1317-25. [PMID: 15906280 DOI: 10.1002/mrm.20495] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The purpose of this study was to evaluate an optimized multislice acquisition technique for oxygen-enhanced MRI of the lung using slice-selective inversion and refocusing pulses in combination with parallel imaging. An inversion recovery HASTE sequence was implemented with respiratory triggering to perform imaging in end-expiration and with ECG triggering to avoid image acquisition during the systolic phase. Inversion pulses and the readout of echo trains could be interleaved to decrease acquisition time. The sequence was evaluated in 15 healthy volunteers, comparing three acquisition schemes: (1) acquisition of four slices without parallel imaging; (2) acquisition of four slices with parallel imaging; (3) acquisition of six slices with parallel imaging. These multislice acquisitions were repeated 80 times with alternating inhalation of room air and oxygen. The oxygen-induced signal increase showed no significant difference with and without parallel imaging. However, only with parallel imaging did the interleaved acquisition of six or more slices become possible, thus enabling a more complete anatomic coverage of the lung. The average required end-expiration time per repetition to acquire six slices could be significantly reduced from 4112 ms without to 2727 ms with parallel imaging. Total acquisition time varied between 8 and 13 min depending on the respiratory frequency.
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Affiliation(s)
- Olaf Dietrich
- Department of Clinical Radiology-Grosshadern, Ludwig Maximilian University of Munich, 81377 Munich, Germany.
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Bankier AA, O'Donnell CR, Mai VM, Storey P, De Maertelaer V, Edelman RR, Chen Q. Impact of lung volume on MR signal intensity changes of the lung parenchyma. J Magn Reson Imaging 2005; 20:961-6. [PMID: 15558552 DOI: 10.1002/jmri.20198] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To test the hypothesis that, in magnetic resonance (MR) imaging of healthy individuals, equal relative changes in lung volume cause equal relative changes in MR signal intensity of the lung parenchyma. MATERIALS AND METHODS In two experimental runs, 10 volunteers underwent spirometrically monitored MR imaging of the lungs, with MR images acquired at 10 incremental lung volumes ranging from total lung capacity to 10% above residual volume. Average signal intensity, signal variability, and signal intensity integrals were calculated for each volunteer and for each lung volume. The effect of lung volume on signal intensity was quantified using linear regression analysis complemented by the runs test. Slopes and intercepts of regression lines were compared with an analysis of covariance. Slopes of the lines of best fit for lung volumes and signal intensities from the two runs were compared to the slope of the line of identity. Comparisons between the two runs were visualized using Bland and Altman plots. RESULTS The slopes of the 10 individual regression lines yielded no significant differences (F = 1.703, P = 0.101; F = 1.321, P = 0.239). The common slopes were -0.556 +/- 0.027 (P = 0.0001) for the first and -0.597 +/- 0.0031 (P = 0.0001) for the second experimental run. Both slopes displayed no significant nonlinearity (P = 0.419 and P = 0.067). There was a strong association between changes in lung volumes (rs = 0.991, P = 0.0001) and changes in signal intensity (rs = 0.889, P = 0.0001) in the two experimental runs. Lines of best fit for lung volume and signal intensities were not significantly different from the slope of the line of identity (P = 0.321 and P = 0.212, respectively). CONCLUSION Equal changes in lung volume cause equal changes in MR signal intensity of the lung parenchyma. This linear and reproducible phenomenon could be helpful in comparing pulmonary MR signal intensity between individuals.
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Stadler A, Jakob PM, Griswold M, Barth M, Bankier AA. T1 mapping of the entire lung parenchyma: Influence of the respiratory phase in healthy individuals. J Magn Reson Imaging 2005; 21:759-64. [PMID: 15906333 DOI: 10.1002/jmri.20319] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To determine the effect of respiratory phase on the T1 values of the entire lung. MATERIALS AND METHODS We calculated T1 relaxation time on a pixel-by-pixel analysis of a series of Snapshot FLASH tomograms acquired after a single inversion pulse. Two sets of coronal T1 maps were acquired, one in full suspended inspiration and one in suspended expiration. RESULTS The average of the mean T1 values over the entire lung in inspiration was 1199+/-117 msec, the average of the mean T1 values in expiration was 1333+/-167 msec. This difference was statistically significant, at P=0.005. In inspiration the average coefficient of variation was 182+/-56 msec, in expiration it was 153+/-41 msec. This difference was not statistically significant. CONCLUSION T1 measurements of the entire lung are feasible. Our findings underline the need for a close monitoring of the inspirational status during MR examinations of the thorax, notably when T1 measurements of the lung are performed.
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Affiliation(s)
- Alfred Stadler
- Department of Radiology, Medical University of Vienna, Vienna, Austria.
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Jakob PM, Wang T, Schultz G, Hebestreit H, Hebestreit A, Elfeber M, Hahn D, Haase A. Magnetization transfer short inversion time inversion recovery enhanced 1H MRI of the human lung. MAGMA (NEW YORK, N.Y.) 2002; 15:10-7. [PMID: 12413560 DOI: 10.1007/bf02693839] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The unique characteristics of the human lung arising from low proton density and multiple air-tissue interfaces of the alveoli cause difficulty in 1H lung magnetic resonance imaging. In addition, the dominating signal from sources such as the thoracic muscle and subcutaneous fat hampers the visualization of the lung parenchyma. In this contribution, an efficient tissue suppression technique is presented which allows one to significantly enhance lung parenchyma visibility. A short inversion time inversion recovery (STIR) experiment combined with a magnetization transfer (MT) experiment was used for magnetization preparation in order to suppress the signal from muscle. A half-Fourier single-shot turbo spin-echo sequence was used as acquisition module. This approach was used to perform lung anatomical imaging in eight healthy human subjects and five patients with cystic fibrosis. The results obtained demonstrate that with MT-STIR approach high quality human lung images can be obtained and that this approach has the potential for the evaluation of lung pathologies.
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Affiliation(s)
- Peter M Jakob
- Department of Physics, Physikalisches Institut, EP 5, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany.
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Knight-Scott J, Keilholz-George SD, Mai VM, Christopher JM. Temporal dynamics of blood flow effects in half-Fourier fast spin echo (1)H magnetic resonance imaging of the human lungs. J Magn Reson Imaging 2001; 14:411-8. [PMID: 11599065 DOI: 10.1002/jmri.1201] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A cardiac-triggered half-Fourier single-shot turbo spin echo (HASTE) technique is currently the method of choice for MR imaging of the lung parenchyma without the use of exogenous contrast agents. In this study, we specifically examined the effects of the cardiac cycle on the HASTE signal intensity of the lungs. Images were obtained from six healthy human volunteers at an end expiration breath-hold using a HASTE sequence and a variable cardiac-triggered delay time. Analysis of the data sets showed a 30% decrease in the lung signal intensity during systole, and a 15% decrease during mid-diastole. These decreases correlate with phases of the cardiac cycle when the blood flow in the lungs is expected to be greatest. Misregistration artifacts, particularly from the pulmonary arteries and aorta, are worse during these periods of signal decrease. To minimize cardiac dependent signal losses, HASTE lung imaging should be performed after systole but before rapid filling of the ventricles.
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Affiliation(s)
- J Knight-Scott
- Department of Biomedical Engineering, University of Virginia Health System, 1105 W. Main St., Charlottesville, VA 22903, USA.
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