| Abstract |
Objectives: The objectives of the present study were to (i) investigate a potential
correlation between transthoracic lung ultrasound (US) findings and high-resolution
computed tomography (HRCT), (ii) to compare a comprehensive lung US protocol in
two different patient positions (sitting/supine and lateral decubitus) with regard to
feasibility, duration, patient convenience and assessment of B-lines, using HRCT as a
reference standard and (iii) to compare a simplified US protocol in two different
patient positions (sitting and lateral decubitus) with the same-positioned
comprehensive US assessments and HRCT findings, in patients with idiopathic
pulmonary fibrosis (IPF).
Methods: Twenty-five consecutive patients with an established IPF diagnosis
according to international guidelines were prospectively enrolled and examined in two
sessions. During session 1, patients were examined twice with a 56-lung intercostal
space (LIS) US protocol, in the supine/sitting (comprehensive protocol 1) and lateral
decubitus (comprehensive protocol 2) positions. During session 2, patients were
evaluated twice with a 16-LIS US protocol, in sitting (simplified protocol 1) and
left/right lateral decubitus (simplified protocol 2) positions. The 16-LIS were chosen
based on the prevalence of IPF-related changes on HRCT. For each patient, the sum
of B-lines counted in all LIS during comprehensive protocol 1, comprehensive
protocol 2, simplified protocol 1 and simplified protocol 2, formed the comprehensive
US score 1 (cUS score 1), comprehensive US score 2 (cUS score 2), simplified US
score 1 (sUS score 1) and simplified US score 2 (sUS score 2), respectively. HRCTrelated
Warrick scores (WS) were compared to US scores. The duration of each
protocol was recorded in minutes. All patients were questioned about their preference
for comprehensive protocol 1 versus comprehensive protocol 2 and simplifiedprotocol 1 versus simplified protocol 2, in terms of convenience. The interobserver
and intraobserver variability were assessed for comprehensive and simplified
protocols.
Results: Twenty-five patients (19 males, 6 females; mean age ± SD: 69.8 ± 7.56
years; age range: 55-83 years) were included. Mean WS was 18 (SD 4.72). A total of
1.400 LIS was assessed, for each comprehensive US protocol with four exceptions:
the examination of the left 4th LIS along the parasternal line in one patient, the
examination of the left 3rd and 4th LIS along the parasternal line in another patient and
the depiction of the left 11th LIS along the paravertebral line in a third patient. A total
of 400 LIS was evaluated for each simplified US protocol with one exception: the
depiction of the left 11th LIS along the paravertebral line. A significant correlation
was found between all US scores and Warrick scores (P&llllllt;.0001). The cUS scores 2
and sUS scores 2 showed slight higher correlation with Warrick scores compared to
cUS scores 1 and sUS scores 1, respectively. A positive correlation was found
between cUS score 1 and sUS score 1 (r2=0.9; P<0.0001) as well as between cUS
score 2 and sUS score 2 (r2=0.91; P<0.0001). There was no statistically significant
difference between cUS scores 1 and cUS scores 2 (P=0.297) as well as between sUS
score 1 and sUS score 2 (P=0.065); however, the cUS scores 2 and sUS scores 2 were
lower than cUS scores 1 and sUS score 1, respectively, in all patients. Mean duration
of simplified protocols 1 and 2 was 4.76 and 6.2 minutes, respectively (P<0.005) and
mean duration of comprehensive protocols 1 and 2 was 22.8 and 19.2 minutes,
respectively (P<0.0001). Significant differences between the duration of the
simplified protocol 1 and 2 compared to those of comprehensive protocol 1 and 2,
respectively, was found (P<0.0001). For comprehensive protocols 1 and 2, the kappa
values for interobserver/intraobserver variability were 0.809/0.817 and 0.825/0.812, respectively. For simplified protocols 1 and 2, the kappa values for
interobserver/intraobserver variability were 0.794/0.828 and 0.834/0.846,
respectively. Twenty-four out of 25 patients (96%) reported preference for
comprehensive protocol 2 versus 1, while 14 patients (56%) preferred simplified
protocol 2 versus 1.
Conclusions: The degree of pulmonary fibrosis could be assessed by both
comprehensive and simplified US methods, in IPF patients. Comprehensive and
simplified lung US protocols in lateral decubitus position appeared to be faster and
more convenient for the patients, while there was no difference regarding feasibility
compared to the sitting/supine position. The number of B-lines detected during
comprehensive and simplified methods correlated with HRCT findings, while
examination in the lateral decubitus position showed slight higher correlation.
Simplified lung US protocols correlated with comprehensive protocols, regardless of
patient positioning.
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