Browsing by Author "Mammarappallil, Joseph"

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    Generalized Linear Binning to Compare Hyperpolarized 129Xe Ventilation Maps Derived from 3D Radial Gas Exchange Versus Dedicated Multislice Gradient Echo MRI.
    (Academic radiology, 2019-11-27) He, Mu; Wang, Ziyi; Rankine, Leith; Luo, Sheng; Nouls, John; Virgincar, Rohan; Mammarappallil, Joseph; Driehuys, Bastiaan
    RATIONALE:Hyperpolarized 129Xe ventilation MRI is typically acquired using multislice fast gradient recalled echo (GRE), but interleaved 3D radial 129Xe gas transfer MRI now provides dissolved-phase and ventilation images from a single breath. To investigate whether these ventilation images provide equivalent quantitative metrics, we introduce generalized linear binning analysis. METHODS:This study included 36 patients who had undergone both multislice GRE ventilation and 3D radial gas exchange imaging. Images were then quantified by linear binning to classify voxels into one of four clusters: ventilation defect percentage (VDP), Low-, Medium- or High-ventilation percentage (LVP, MVP, HVP). For 3D radial images, linear binning thresholds were generalized using a Box-Cox rescaled reference histogram. We compared the cluster populations from the two ventilation acquisitions both numerically and spatially. RESULTS:Interacquisition Bland-Altman limits of agreement for the clusters between 3D radial vs GRE were (-7% to 5%) for VDP, (-10% to 14%) for LVP, and (-8% to 8%) for HVP. While binning maps were qualitatively similar between acquisitions, their spatial overlap was modest for VDP (Dice = 0.5 ± 0.2), and relatively poor for LVP (0.3 ± 0.1) and HVP (0.2 ± 0.1). CONCLUSION:Both acquisitions yield reasonably concordant VDP and qualitatively similar maps. However, poor regional agreement (Dice) suggests that the two acquisitions cannot yet be used interchangeably. However, further improvements in 3D radial resolution and reconciliation of bias field correction may well obviate the need for a dedicated ventilation scan in many cases.
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    ItemOpen Access
    Pulmonary Delivery of Therapeutic and Diagnostic Gases.
    (Journal of aerosol medicine and pulmonary drug delivery, 2018-04) Zapol, Warren M; Charles, H Cecil; Martin, Andrew R; Sá, Rui C; Yu, Binglan; Ichinose, Fumito; MacIntyre, Neil; Mammarappallil, Joseph; Moon, Richard; Chen, John Z; Geier, Eric T; Darquenne, Chantal; Prisk, G Kim; Katz, Ira
    The 21st Congress for the International Society for Aerosols in Medicine included, for the first time, a session on Pulmonary Delivery of Therapeutic and Diagnostic Gases. The rationale for such a session within ISAM is that the pulmonary delivery of gaseous drugs in many cases targets the same therapeutic areas as aerosol drug delivery, and is in many scientific and technical aspects similar to aerosol drug delivery. This article serves as a report on the recent ISAM congress session providing a synopsis of each of the presentations. The topics covered are the conception, testing, and development of the use of nitric oxide to treat pulmonary hypertension; the use of realistic adult nasal replicas to evaluate the performance of pulsed oxygen delivery devices; an overview of several diagnostic gas modalities; and the use of inhaled oxygen as a proton magnetic resonance imaging (MRI) contrast agent for imaging temporal changes in the distribution of specific ventilation during recovery from bronchoconstriction. Themes common to these diverse applications of inhaled gases in medicine are discussed, along with future perspectives on development of therapeutic and diagnostic gases.