Perfusion imaging of the human lung using flow-sensitive alternating inversion recovery with an extra radiofrequency pulse (FAIRER)

Purpose: To investigate the optimal oxygen flow rate for oxygen-enhanced MR ventilation imaging. Materials and Methods:Using a cardiac-triggered nonselective inversion recovery (IR) half Fourier single-shot fast spin echo sequence, series of images were acquired with the subject alternately inhaling room air and 100% oxygen. Oxygen flow rates of 5 L/min, 10 L/min, 15 L/min, 20 L/min, and 25 L/min were studied, and signal intensity from the oxygen-enhanced ventilation images and T 1 of the lung were measured. OXYGEN-ENHANCED MAGNETIC RESONANCE IMAG-ING has been used to assess regional ventilation of the lung in patients with pulmonary diseases and in animal models (1-4). Although oxygen is weakly paramagnetic, its overall effect on the lung is considerable given the large surface area of the lung and the large difference in partial pressures between room air and 100% oxygen. ResultsRelative to breathing room air, inhaling 100% oxygen increases concentration of dissolved oxygen in blood and lung tissue as more oxygen diffuses across the lung parenchyma and dissolves into blood and lung tissues. Consequently, increased concentration of dissolved oxygen in the lung will shorten its longitudinal relaxation time (T 1 ), enabling the detection of signal change if T 1 -weighted sequences such as inversion recovery (IR) or multiple IR are used for image acquisition (1-8). Generally, the procedure of the oxygen-enhanced ventilation imaging technique involves the acquisition of series of images with the subject alternately inhaling room air and 100% oxygen. The difference between the average images of the two states yields the oxygenenhanced ventilation image.To date, oxygen-enhanced ventilation imaging has been performed using different flow rates (1-7,9,10), while no study thus far has been conducted to determine the influence of oxygen flow rate on the signal and T 1 changes in the lung. Logically, if more oxygen dissolves in blood plasma in the lung, a larger detected signal change will result. However, the solubility of oxygen in blood plasma is poor, and therefore a low saturation point would be quickly established. Thus, there should exist an optimal point for changes in signal intensity and T 1 of the lung. The purpose of this study was to investigate the effect of oxygen flow rate for ventilation imaging of the lung with inhalation of 100% oxygen. More specifically, we sought to determine the oxygen flow rate at which optimal changes in signal intensity and T 1 of the lung occur. MATERIALS AND METHODSAll imaging experiments were performed on a CV/i 1.5 T system (GE Medical Systems, Milwaukee, WI) equipped with 40 mT/m gradients and a slew rate of 150 T/m/second. A four-element, receiver phased-array coil was used. Six healthy human volunteers (three males and three females, 25-48 years old, average age 33.7 Ϯ 6.5 years) were imaged. Written informed consent was obtained from each volunteer before experimentation.A series of 60 images at TI of 1200 msec were acquired at each flow rate while the subjects alternately...

Section: Discussionsupporting

confidence: 92%

Influence of oxygen flow rate on signal and T₁ changes in oxygen‐enhanced ventilation imaging

Liu

et al. 2002

“…The obtained perfusion rates are in good agreement with recent publications (7,(22)(23)(24). If one considers a total lung volume in deep expiration of 2-3 L and a total circulation volume of 5-6 L/min, one obtains perfusion rates of Ϸ2 mL/min/mL.…”

Section: Discussionsupporting

confidence: 90%

“…Quantification with ASL has been shown recently (6), but this method is at the moment more commonly used to obtain perfusion qualitatively. Furthermore, it is possible to acquire tag and control images in a single breath-hold (6,7), but for most patients who suffer from severe lung damage a breath-hold time of Ϸ20 seconds is not possible. This disadvantage holds for contrast-enhanced MR as well.…”

mentioning

confidence: 99%

Assessment of pulmonary perfusion in a single shot using SEEPAGE

Fischer¹,

Pracht²,

Arnold³

et al. 2007

Purpose: To present a single-shot perfusion imaging sequence that does not require contrast agents or a subtraction of a tag and a control image to create the perfusionweighted contrast. The proposed method is based on SEEPAGE. Materials and Methods:Experiments with healthy volunteers were performed to qualitatively and quantitatively obtain pulmonary perfusion values in coronal as well as sagittal orientation. In addition, a first experiment with a lung cancer patient was performed to explore the potentials of SEEPAGE in a clinical application. Results:All experiments clearly showed a perfusionweighted contrast, providing clinical quality images with high spatial resolution. The quantified perfusion rates were consistent in the different imaging orientations and covered the interval of 1.00 -4.00 mL/min/mL. In addition, the gravitational dependence of pulmonary perfusion, the influence of adiabatic pulse duration on signal intensity, and the tracer saturation effect were examined. In the patient examination the presented technique provided additional information of the lung deficiency compared to a conventional anatomical image.Conclusion: SEEPAGE has proved to be a robust and reproducible technique for obtaining perfusion-weighted images in a single measurement and for quantifying pulmonary perfusion using an additional reference scan. Furthermore, the proposed method shows promise for future clinical application.

“…An arterial spin labeling technique called FAIRER was used (23,24). Inflowing blood was labeled by inverting its magnetization.…”

Section: Perfusion Imagingmentioning

confidence: 99%

“…Arterial spin labeling, originally proposed to measure cerebral blood flow (19 -21), uses blood water as an endogenous, freely diffusible tracer, and has been successfully demonstrated to image pulmonary perfusion (23)(24)(25). In this study, we present a V/Q imaging scheme by combining oxygen-enhanced and an arterial spin labeling technique called flow-sensitive alternating inversion recovery with an extra radiofrequency pulse (FAIRER), which has been previously described (23,24).…”

mentioning

confidence: 99%

MR ventilation‐perfusion imaging of human lung using oxygen‐enhanced and arterial spin labeling techniques

Bankier

Prasad

et al. 2001

Magnetic resonance ventilation-perfusion (V/Q) imaging has been demonstrated using oxygen and arterial spin labeling techniques. Inhaled oxygen is used as a paramagnetic contrast agent in ventilation imaging using a multiple inversion recovery (MIR) approach. Pulmonary perfusion imaging is conducted using a flow-sensitive alternating inversion recovery with an extra radiofrequency pulse (FAIRER) technique. A half Fourier single-short turbo spin echo (HASTE) sequence is used for data acquisition in both techniques. V/Q imaging was performed in ten of the twenty volunteers, while either ventilation or perfusion was imaged in the other ten. This V/Q imaging scheme is completely noninvasive, does not involve ionized radiation, and shows promising potential for clinical use in the diagnosis of lung diseases such as pulmonary embolism. J. Magn. Reson. Imaging 2001;14: 574 -579.