Fast magnetic resonance imaging of the lung

Hatabu, Hiroto; Chen, Qun; Stock, K.; Gefter, Warren B.; Itoh, Harumi

doi:10.1016/s0720-048x(98)00174-0

Cited by 80 publications

(57 citation statements)

References 59 publications

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“…In contrast, MRI does not rely on ionizing radiation and permits ventilation imaging of the lungs with high spatial and temporal resolution using paramagnetic contrast agents. However, MRI of the lung parenchyma is problematic because of relatively low number of hydrogen protons, cardiac and respiratory motion, and susceptibility effects induced by multiple air and tissue interfaces (10,26,27). These problems can be overcome by the use of pulse sequences with a very short echo time (TE), breath hold imaging, and cardiac gating.…”

Section: Discussionmentioning

confidence: 99%

Aerosol Delivery in Ventilated Newborn Pigs: An MRI Evaluation

et al. 2008

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Pulmonary deposition of inhaled drugs in ventilated neonates has not been studied in vivo. The objective of this study was to evaluate pulmonary delivery of gadopentetate dimeglumine (Gd-DTPA) following nebulization in ventilated piglets using magnetic resonance imaging. Seven ventilated piglets (5 Ϯ 2 d old, weight 1.8 Ϯ 0.5 kg) were scanned in the Bruker/Siemens 4T magnetic resonance scanner using T1 weighted spin-echo sequence. Aerosols of Gd-DTPA were generated continuously using the MiniHeart jet nebulizer. Breath-hold coronal images were obtained before and every 10 min during aerosolized Gd-DTPA for 90 min. Signal intensity (SI) changes over the lungs, kidneys, liver, skeletal muscle, and heart were evaluated. A significant increase in SI was observed in the lungs, kidney, and liver at 10, 20, and 40 min respectively after start of aerosol. At the end of 90 min, the SI increased by 95%, 101%, and 426% over the right lung, left lung, and kidney, respectively. A much smaller increase in SI was observed over the liver. In conclusion, we have demonstrated effective pulmonary aerosol delivery within 10 min of contrast nebulization in ventilated piglets. Contrast visualization in the kidneys within 20 min of aerosol initiation reflects alveolar absorption, glomerular filtration and renal concentration. (Pediatr Res 64: 159-164, 2008)

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Section: Discussionmentioning

confidence: 99%

Aerosol Delivery in Ventilated Newborn Pigs: An MRI Evaluation

et al. 2008

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“…In combination with current MR techniques used to assess pulmonary ventilation (20)(21)(22)(23)(24), regional pulmonary ventilation-perfusion ratios could be determined. These could be used to further understand the control of pulmonary function to maintain effective gas exchange in the lung (25,26).…”

Section: Discussionmentioning

confidence: 99%

Quantitative assessment of pulmonary perfusion with dynamic contrast-enhanced MRI

et al. 1999

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“…However, ultrashort-TE pulse sequences are harder to implement for large fields of view, and the acquisition generally takes several minutes. In the immediate future, standard gradient echo and turbo spin sequences with relatively short TEs are more tenable (22,24).…”

Section: (3)mentioning

confidence: 99%

“…The lungs have a low proton density (22) and short transverse relaxation time (T 2 *) (23,24), compromising available MRI signal. Also, the lungs are mobile and highly vascular, generating motion and flow artifacts, respectively (22).…”

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confidence: 99%

Variable Lung Density Consideration in Attenuation Correction of Whole-Body PET/MRI

Marshall

Prato²,

Deans³

et al. 2012

J Nucl Med

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Present attenuation-correction algorithms in whole-body PET/ MRI do not consider variations in lung density, either within or between patients; this may adversely affect accurate quantification. In this work, a technique to incorporate patient-specific lung density information into MRI-based attenuation maps is developed and compared with an approach that assumes uniform lung density. Methods: Five beagles were scanned with 18 F-FDG PET/CT and MRI. The relationship between MRI and CT signal in the lungs was established, allowing the prediction of attenuation coefficients from MRI. MR images were segmented into air, lung, and soft tissue and converted into attenuation maps, some with constant lung density and some with patient-specific lung densities. The resulting PET images were compared by both global metrics of quantitative fidelity (accuracy, precision, and root mean squared error) and locally with relative error in volumes of interest. Results: A linear relationship was established between MRI and CT signal in the lungs. Constant lung density attenuation maps did not perform as well as patient-specific lung density attenuation maps, regardless of what constant density was chosen. In particular, when attenuation maps with patient-specific lung density were used, precision, accuracy, and root mean square error improved in lung tissue. In volumes of interest placed in the lungs, relative error was significantly reduced from a minimum of 12% to less than 5%. The benefit extended to tissues adjacent to the lungs but became less important as distance from the lungs increased. Conclusion: A means of using MRI to infer patient-specific attenuation coefficients in the lungs was developed and applied to augment whole-body MRI-based attenuation maps. This technique has been shown to improve the quantitative fidelity of PET images in the lungs and nearby tissues, compared with an approach that assumes uniform lung density.Key Words: PET/MRI; attenuation correction; lung density; segmentation; whole-body imaging Aft er a decade and a half of development, human whole-body PET/MRI systems are now a reality (1). It has been widely speculated that PET/MRI will prove useful in several clinical disciplines (2-4), a prediction that is in the nascent stages of realization (5,6). However, without a means of attenuation correction (AC), accurate quantification in PET is not possible.Multiple approaches have been proposed to create MRIbased attenuation maps (m-maps) (7-15). However, none of these approaches measures the attenuation coefficients (m-coefficients) of the lungs, which vary both between individuals (16) and within a given individual (17,18) and are influenced by inflation (16,17,19), gravitational dependency (18,19), and pathology (18,20,21).Visualizing lung parenchyma with MRI is challenging. The lungs have a low proton density (22) and short transverse relaxation time (T 2 *) (23,24), compromising available MRI signal. Also, the lungs are mobile and highly vascular, generating motion and flow artifacts, respectively...

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Fast magnetic resonance imaging of the lung

Cited by 80 publications

References 59 publications

Aerosol Delivery in Ventilated Newborn Pigs: An MRI Evaluation

Aerosol Delivery in Ventilated Newborn Pigs: An MRI Evaluation

Quantitative assessment of pulmonary perfusion with dynamic contrast-enhanced MRI

Variable Lung Density Consideration in Attenuation Correction of Whole-Body PET/MRI

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