2004 OPEN FORUM Abstracts
ELECTRICAL IMPEDANCE TOMOGRAPHY COMPARED TO COMPUTERIZED TOMOGRAPHY IMAGING OF RADIOLOGIST-CONFIRMED PULMONARY PATHOLOGY.
Amir Ghiassi MD, Alexander Adams RRT, MPH, Ives De
Chazal MD, Dana Simonson BS, John Marini MD.
HealthPartners/Regions Hospital, St.Paul, MN.
Background:
Computerized Tomography (CT) provides high-resolution images of
static pulmonary pathoanatomy. Knowledge of dynamic respiratory
activity such as regional ventilation can only be inferred by CT
images. Electrical impedance tomography (EIT) is a portable (bedside)
monitor that produces active, 2-dimensional video imaging of
ventilation by displaying a color grid via impedance changes of
aerated vs. non-aerated tissue. Our goal was to compare the impedance
change measurements by EIT with pulmonary pathology confirmed from
CT imaging.
Methods: Fourteen (14) patients with
radiologist-confirmed distinct regions of pulmonary pathology were
identified for EIT interrogation.
EIT was recorded at the
patients' bedsides by applying 16 electrodes affixed
circumferentially at the axilla level and obtaining 5-10 minutes of
video imaging.
Results: The mean impedance
change for
regions of interest were: normal: 0.45, effusion: 0.002, infiltrate:
0.05, fibrosis: 0.011, mass: 0.0001.
Differences in impedance
changes between normal and CT-identified pathology were significant
(p<0.01). Note the CT and EIT images (below) illustrating
unilateral pathology with ventilation seen in the contralateral lung
field.
Conclusions: For regions of pulmonary pathology where
ventilation should be diminished according to CT, EIT imaging
verifies that impedance change (ventilation) is minimal. EIT is a
bedside device that can monitor regional lung ventilation.
Limitations included compromised image quality in patients with
excessive adipose tissue and less resolution than CT imaging.
