Stanislao Fichele

Combined helium-3/proton magnetic resonance imaging measurement of ventilated lung volumes in smokers compared to never-smokers.

To use a combination of helium‐3 (3‐He) magnetic resonance imaging (MRI) and proton single‐shot fast spin echo (SSFSE) to compare ventilated lung volumes in groups of “healthy” smokers, smokers diagnosed with moderate chronic obstructive pulmonary disease (COPD), and never‐smokers.

MRI of Helium-3 Gas in Healthy Lungs: Posture Related Variations of Alveolar Size

To probe the variation of alveolar size in healthy lung tissue as a function of posture using diffusion‐weighted helium‐3 hyperpolarized gas imaging.

Finite‐difference simulations of 3He diffusion in 3D alveolar ducts: Comparison with the “cylinder model”

Time‐dependent measurements of 3He diffusion in the lung could provide an accurate method to quantify alveolar length scales and the progression of diseases such as emphysema. However, the apparent diffusion coefficient (ADC) presents a complex problem to model and solve analytically. Here, finite‐difference methods were used to simulate diffusion in 3D alveolar ducts. The results were compared to the only available analytical model—the “cylinder model”—from which it is possible to estimate the average radii of the alveolar ducts from in vivo data. The trend in data observed from simulations was found to agree well with the cylinder model. However, the cylinder model always overestimated the average radii of the simulated alveolar ducts. The simulations also demonstrated that the measurement of the longitudinal ADC (along the alveolar ducts) should be sensitive to early emphysematous changes, whereas the measured radii should be far less sensitive. Magn Reson Med 52:917–920, 2004.

MR imaging of the lungs with hyperpolarized helium-3 gas transported by air

Hyperpolarized noble gas MRI shows promise in the functional imaging of the pulmonary air spaces. The production of hyperpolarized (HP) gas requires specialized laser optical pumping apparatus, which is not likely to be home built in the majority of clinical MRI radiology centres. There are two routes through which HP gas will be made available to hospitals for clinical use: either the apparatus will be installed locally at a considerable expense to the centre, or a central facility will produce the gas and then deliver it to remote MRI sites as and when required. In this study, the feasibility of transporting large quantities of HP gas for in vivo MR imaging from a remote production facility in Mainz, Germany, by airfreight to Sheffield, UK, was successfully demonstrated.

B1AC‐MAMBA: B1 array combined with multiple‐acquisition micro B0 array parallel magnetic resonance imaging

The combination of an in‐plane B1 sensitivity encoding (SENSE) technique with a simultaneous multiple‐slice B0 field step technique (multiple‐acquisition micro B0 array (MAMBA)) has produced high scan time reduction factors (R ≤ 8). In this study, two slices were acquired simultaneously in combination with ×2 and ×4 SENSE in‐plane encoding using a MAMBA stepped B0 field coil inside a four‐channel phased‐array coil system. Experiments were performed on a 1.5 T Infinion system (Philips Medical Systems, Cleveland, OH). The signal‐to‐noise ratio (SNR) was reduced with higher R factors, as was expected from the reduced number of acquisitions used to create the unaliased images. The combination of SENSE and MAMBA offers great promise for reducing scan times through parallel acquisition while at the same time reducing the number of RF channels required by a factor equal to the number of field steps employed. The B1 array combined with MAMBA (B1AC‐MAMBA) technique is applicable when the length of an object is much greater than its diameter, as in scanning limbs or in whole‐body screening for disease. Magn Reson Med 49:1196–1200, 2003.