BACKGROUND
METHODS
• Increasing use of advanced radiology in the
Emergency Department (ED) has been shown
to increase ED length of stay and healthcare
costs.
• CT utilization has been studied more
extensively than MRI, however all data
suggests that both are increasing.
• Very few ED’s in the United States contain MRI
within their department. Consequently, there is
no data regarding changes in utilization when
the MRI is physically located in the ED.
RESULTS
• This is a retrospective cohort investigating MRI
utilization during a one-year period pre-MRI
acquisition and a one-year period post-MRI
acquisition in the ED at a Level 1 Trauma
Center and Comprehensive Stroke Center.
• Overall, MRI’s performed in the ED increased by
104%. ED volume increased by 13.4%, NC
patients increased by 29.5%, and ROS patients
increased by 33.9% during the same time period.
• Data was excluded for a three-month period
following MRI acquisition to account for
changes in physician practice patterns.
• The percent of ROS patients who underwent MRI
increased from 30.5% to 45.5% (p<0.01) and the
percent of NC patients who underwent MRI
increased from 30.36% to 47.37% (p<0.01) after
placement of an MRI in the ED.
• De-identified data for all NC patients and ROS
patients from the two study periods were
compared using z-tests and paired t-tests)
OBJECTIVES
Table 1: ROS Patients
• This study will determine whether there has been
an increase in emergency MRI utilization
following the placement of an MRI in the ED in
April 2012.
• This study will further investigate the effects of ED
MRI on ED and hospital length of stay and
hospital admission rates for rule out stroke (ROS)
and neurology consult (NC) patients in the ED.
• Keywords: advanced radiology, resource
utilization
Pre
Post
P-Value
Total ROS Patients
289
387
n/a
ROS Pts who had
MRI
88 (30.5%)
176 (45.5%)
p<0.01
MRI’s per patient
274/88=3.0
562/176=3.2
p=0.1
ROS pts admitted
208 (72%)
227 (58.7%)
p<0.001
Admitted pts <1 day
LOS
62
60
p=0.4
Admitted ROS
hospital LOS (days)
4.67
4.87
p=0.4
Minutes to ED Dispo
257.24
319.45
p<0.001
ROS – rule out stroke; MRI – magnetic resonance imaging; LOS – length of stay;
ED – Emergency Department
1426
433
Table 2: NC Patients
NC
845
Pre
Post
P-value
Total NC Patients
1426
1812
n/a
NC pts who had MRI
433 (30.36%)
866 (47.79%)
p<0.01
MRI’s per patient
1423/433=3.3
2898/866=3.3
p=1
NC Patients Admitted
845 (59.3%)
1048 (57.8%)
p=0.4
Minutes to ED dispo
562.92
640.28
p<0.001
1812
Post
866
1048
289
Pre
ROS
88
208
387
Post
176
227
0
200
400
600
Total Volume
Figure 1: Patient Volumes
800
1000
Pts who had MRI
1200
1400
Total Admitted Pts
1600
1800
2000
• For NC patients, the admission rate was
unchanged (59.3% vs. 58.1%; p=0.5).
• Both groups experienced an increase in ED LOS.
ROS patients’ ED LOS increased from 257.24
min to 319.45 min (p<0.001) and NC patients’ ED
LOS increased from 562.92 to 638.51 (p<0.001).
CONCLUSIONS
• Overall our study shows an increase in MRI
utilization in the ED for both groups.
Patient Volumes
Pre
• For ROS patients, the admission rate decreased
from 72% to 59% (p<0.001), however, the
number of one-day admissions was unchanged
(62 vs. 60; p=0.4) and the inpatient LOS was
unchanged (4.67 vs. 4.87 days; p=0.4).
NC – neurology consult; MRI – magnetic resonance imaging; LOS – length of stay;
ED – Emergency Department
• While this decreased the admission rate for
ROS patients, the ED LOS for both groups
increased.
• Limitations: retrospective, unadjusted length of
stay, single site
• This is one of the first ED’s in the country to
have an MRI in the ED and the resulting
utilization and throughput changes should be a
consideration for future ED’s considering MRI
acquisition.