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Detection of longitudinal lung structural and functional changes after diagnosis of radiation‐induced lung injury using hyperpolarized He 3 magnetic resonance imaging
Author(s) -
Mathew Lindsay,
Gaede Stewart,
Wheatley Andrew,
EtemadRezai Roya,
Rodrigues George B.,
Parraga Grace
Publication year - 2010
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3263616
Subject(s) - medicine , lung , magnetic resonance imaging , spirometry , lung volumes , effective diffusion coefficient , radiology , nuclear medicine , pulmonary function testing , radiation therapy , asthma
Purpose Therapeutic radiation doses for thoracic tumors are significantly restricted to decrease the risk of nontumor tissue damage, yet radiation‐induced lung injury (RILI) still occurs in over 1 ∕ 3 of thoracic radiation treatment cases. Although RILI can be clinically monitored using pulmonary function measurements, the regional functional effects of the injury are not well understood. Hyperpolarized He3 magnetic resonance imaging provides measurements of regional lung function and structure with high spatial and temporal resolution; the authors use this tool longitudinally for the first time in seven subjects after clinical diagnosis of RILI in order to better understand regional changes in lung function and structure post‐RILI. Methods All subjects underwent spirometry, plethysmography, and MRI at3 . 0T35 . 1 ± 12 . 2weeks after radiation therapy commenced. Thoracic H1 , static He3 ventilation, and He3 diffusion‐weighted images were acquired to generate the He3 apparent diffusion coefficient (ADC) and He3 percent ventilated volume (PVV). Four subjects returned22 . 0 ± 0 . 8weeks after baseline imaging for follow‐up spirometry and He3 MRI measurements of ADC and PVV. Results At baseline, PVV was significantly different ( p = 0 . 025 ) and lower in the ipsilateral diseased lung ( 55 ± 29 % ) compared to the contralateral nondiseased lung ( 88 ± 5 % ) . Longitudinally, significant increases were observed for He3 MRI PVV ( 16 % ± 6 % , p = 0 . 012 ) and He3 MRI ADC ( 0 . 02 ± 0 . 01cm 2 ∕ s , p = 0 . 003 ) in the contralateral lung only, in the four subjects who returned for follow‐up, while no changes in the ipsilateral lung were reported. Conclusions Hyperpolarized He3 MRI was well tolerated in all subjects with moderate to severe RILI. Functional improvements and microstructural changes were observed in the contralateral lung, while the ipsilateral lung remained stable, suggesting that functional compensatory changes may have occurred in the contralateral lung due to ipsilateral lung radiation‐induced injury.