Dual-source

computed

tomography

in

patients

with

acute

chest

pain

feasibility

and

image

quality

The

aim

of

this

study

was

to

determine

the

feasibility

and

image

quality

of

dual-source

computed

tomography

angiography

-LRB-

DSCTA

-RRB-

in

patients

with

acute

chest

pain

for

the

assessment

of

the

lung

thoracic

aorta

and

for

pulmonary

and

coronary

arteries

Sixty

consecutive

patients

-LRB-

female

male

mean

age

years

-RRB-

with

acute

chest

pain

underwent

contrast-enhanced

electrocardiography-gated

DSCTA

without

prior

beta-blocker

administration

Vessel

attenuation

of

different

thoracic

vascular

territories

was

measured

and

image

quality

was

semi-quantitatively

analyzed

by

two

independent

readers

Image

quality

of

the

thoracic

aorta

was

diagnostic

in

all

patients

image

quality

of

pulmonary

arteries

was

diagnostic

in

and

image

quality

of

coronary

arteries

was

diagnostic

in

patients

Pairwise

intraindividual

comparisons

of

attenuation

values

were

small

and

ranged

between

HU

comparing

right

and

left

coronary

artery

and

HU

comparing

the

pulmonary

trunk

and

left

ventricle

Mean

attenuation

was

HU

in

the

ascending

aorta

HU

in

the

pulmonary

trunk

and

HU

and

HU

in

the

right

and

left

coronary

artery

respectively

DSCTA

is

feasible

and

provides

diagnostic

image

quality

of

the

thoracic

aorta

pulmonary

and

coronary

arteries

in

patients

with

acute

chest

pain

Introduction

Acute

chest

pain

represents

one

of

the

most

difficult

diagnostic

challenges

in

emergency

medicine

Chest

pain

history

alone

often

can

not

identify

a

group

of

patients

who

could

be

treated

without

further

diagnostic

testing

-LSB-

-RSB-

and

triage

decisions

based

on

initial

cardiac

enzyme

levels

-LSB-

-RSB-

and

electrocardiography

-LRB-

ECG

-RRB-

-LSB-

-RSB-

are

often

insufficient

Imaging

may

improve

patient

triage

by

decreasing

delay

in

diagnosis

and

treatment

and

thus

morbidity

and

mortality

-LSB-

-RSB-

Most

studies

-LSB-

-RSB-

have

focused

on

patients

being

suspected

of

having

acute

coronary

syndrome

but

did

not

include

additional

differential

diagnoses

such

as

aortic

dissection

or

pulmonary

embolism

conditions

that

may

clinically

mimic

coronary

syndromes

-LSB-

-RSB-

Multi-detector

row

computed

tomography

-LRB-

CT

-RRB-

angiography

is

widely

accepted

and

routinely

used

as

a

primary

tool

in

the

emergency

assessment

of

pulmonary

embolism

-LSB-

-RSB-

and

aortic

dissection

-LSB-

-RSB-

In

addition

CT

coronary

angiography

has

demonstrated

the

capability

to

diagnose

and

to

rule-out

coronary

artery

disease

-LRB-

CAD

-RRB-

-LSB-

-RSB-

Some

recent

studies

have

shown

that

ECG-gated

multi-detector

row

CT

is

logistically

feasible

-LSB-

-RSB-

and

yields

promising

results

as

a

modality

for

evaluating

chest

pain

patients

with

cardiac

and

non-cardiac

disease

in

the

emergency

setting

-LSB-

-RSB-

Even

though

using

CT

scanner

technology

however

patients

with

elevated

heart

rates

require

medical

heart

rate

control

prior

to

CT

coronary

angiography

by

administering

beta-blockers

and/or

benzodiazepines

-LSB-

-RSB-

Dual-source

CT

-LRB-

DSCT

-RRB-

represents

the

most

recent

scanner

technology

and

is

characterized

by

two

tubes

and

two

detectors

that

are

mounted

in

orthogonal

orientation

onto

the

gantry

As

compared

to

CT

this

scanner

configuration

maintains

a

consistently

high

spatial

resolution

while

enabling

ECG-gated

imaging

with

an

increased

temporal

resolution

of

ms

-LSB-

-RSB-

First

studies

have

shown

robust

results

of

DSCT

angiography

-LRB-

DSCTA

-RRB-

regarding

image

quality

of

cardiac

structures

even

at

high

heart

rates

-LSB-

-RSB-

The

purpose

of

this

study

was

to

investigate

the

feasibility

and

image

quality

of

ECG-gated

DSCTA

of

the

chest

as

a

tool

to

evaluate

cardiac

and

non-cardiac

causes

of

acute

chest

pain

in

patients

presenting

to

the

emergency

department

Materials

and

methods

Patient

population

Sixty

consecutive

patients

-LRB-

females

males

mean

age

years

age

range

years

-RRB-

were

prospectively

included

in

this

study

Intake

was

performed

on

weekdays

from

am

to

pm

from

August

to

October

All

patients

suffered

from

acute

chest

pain

and

were

referred

to

our

department

to

diagnose

or

to

rule

out

pulmonary

embolism

-LRB-

n

-RRB-

or

aortic

dissection

-LRB-

n

-RRB-

Inclusion

criteria

were

acute

chest

pain

min

within

the

previous

h

and/or

elevated

serum

D-dimer

levels

Dyspnea

and

hemodynamic

instability

were

not

considered

exclusion

criteria

Similarly

all

patients

irrespective

of

their

mean

or

regularity

of

heart

rate

and

irrespective

of

their

ability

to

perform

breath-hold

were

included

Exclusion

criteria

included

pregnancy

previous

adverse

reaction

to

iodinated

contrast

agent

nephropathy

-LRB-

serum

creatinine

mg/dl

-RRB-

elevated

troponine-I

or

creatine

kinase-MB

level

in

the

initial

blood

sample

initial

diagnostic

ECG

changes

indicating

an

acute

coronary

syndrome

-LRB-

i.e.

ST

elevation

or

depression

mm

T-wave

inversion

mm

in

anatomically

contagious

leads

-RRB-

and

interference

with

standard

clinical

care

of

patients

The

study

was

approved

by

the

local

ethics

committee

informed

consent

was

obtained

Scan

protocol

and

data

reconstruction

All

CT

examinations

were

performed

on

a

DSCT

scanner

-LRB-

Somatom

Definition

Siemens

Medical

Solutions

Forchheim

Germany

-RRB-

First

a

single

non-enhanced

low-dose

scan

at

the

level

of

the

aortic

root

was

obtained

In

this

slice

a

region

of

interest

-LRB-

ROI

-RRB-

was

set

in

the

lumen

of

the

aorta

for

monitoring

intraluminal

contrast

enhancement

The

delay

from

start

of

contrast

material

injection

to

start

of

scanning

was

planned

using

the

bolus-tracking

technique

A

total

of

ml

iodinated

contrast

material

-LRB-

iodixanol

Visipaque

mg/ml

GE

Healthcare

Buckinghamshire

UK

-RRB-

was

administered

at

a

flow

rate

of

ml/s

via

an

needle

placed

into

a

superficial

vein

in

the

left

antecubital

fossa

followed

by

ml

saline

solution

at

the

same

flow

rate

-LRB-

ml/s

-RRB-

After

reaching

the

preset

contrast

enhancement

level

of

Hounsfield

Units

-LRB-

HU

-RRB-

in

the

ROI

a

breath-hold

signal

was

given

and

the

scan

was

initiated

automatically

after

a

delay

of

s

A

topogram

was

used

for

planning

the

examination

and

determining

the

scan

range

Data

acquisition

was

performed

using

a

dedicated

biphasic

chest

pain

protocol

As

illustrated

in

Fig.

the

lower

chest

including

the

heart

was

scanned

with

a

tube

current

time

of

mAs

while

the

upper

chest

was

scanned

with

a

tube

current

time

product

of

mAs

The

borderline

between

upper

and

lower

scan

range

was

set

at

approximately

cm

below

the

carina

Data

acquisition

was

performed

in

a

cranio-caudal

direction

Acquisition

parameters

were

as

follows

detector

collimation

mm

by

using

a

z-flying

focal

spot

for

the

simultaneous

acquisition

of

overlapping

slices

gantry

rotation

time

ms

and

tube

potential

kV

The

pitch

varied

according

to

the

patient

's

heart

rate

and

ranged

from

with

higher

pitch

at

higher

heart

rates

ECG-pulsing

for

radiation

dose

reduction

-LSB-

-RSB-

was

applied

in

all

patients

At

mean

heart

rates

below

bpm

full

tube

current

was

applied

from

to

at

bpm

from

to

and

at

heart

rates

above

from

to

of

the

R-R

interval

Fig.

topogram

illustrating

planning

of

the

chest

pain

protocol

The

scan

range

covered

the

entire

chest

-LRB-

red

box

-RRB-

Premonitoring

for

bolus

tracking

was

performed

at

the

level

of

the

aortic

root

-LRB-

white

line

-RRB-

The

border

for

full

tube

current

for

the

heart

and

half

tube

current

for

the

upper

lung

is

set

approximately

cm

below

the

tracheal

bifurcation

It

is

delimited

by

a

virtual

horizontal

line

connecting

the

upper

ends

of

the

blue

boxes

on

both

sides

Retrospective

ECG-gating

for

phase

synchronization

was

used

For

the

heart

CT

data

sets

were

reconstructed

at

of

the

R-R

interval

with

a

slice

thickness

of

mm

-LRB-

increment

mm

-RRB-

by

using

a

medium

soft-tissue

convolution

kernel

-LRB-

-RRB-

-LRB-

mean

field

of

view

FoV

mm

image

matrix

-RRB-

If

considered

necessary

additional

images

were

reconstructed

in

steps

using

the

same

parameters

within

the

time

window

of

full

tube

current

Images

of

the

mediastinum

-LRB-

mean

FoV

mm

-RRB-

including

the

aorta

and

pulmonary

arteries

were

reconstructed

with

a

slice

thickness

of

mm

-LRB-

increment

mm

-RRB-

by

using

a

medium

soft-tissue

convolution

kernel

-LRB-

-RRB-

and

images

of

the

lung

were

reconstructed

with

a

slice

thickness

of

mm

-LRB-

increment

mm

-RRB-

by

using

a

sharp

convolution

kernel

-LRB-

same

FoV

as

for

the

mediastinum

-RRB-

All

images

were

transferred

to

a

second

Wizard

-LRB-

Siemens

-RRB-

equipped

with

cardiac

post-processing

software

-LRB-

Syngo

Circulation

Siemens

-RRB-

Data

analysis

All

data

were

qualitatively

evaluated

regarding

image

quality

and

artifacts

of

different

thoracic

structures

by

two

independent

readers

who

are

both

experienced

in

cardiovascular

radiology

This

evaluation

was

performed

on

transverse

source

images

multi-planar

reformations

-LRB-

MPR

-RRB-

curved

MPR

and

thin-slab

maximum

intensity

projections

Image

quality

and

artifacts-lung

parenchyma

Image

quality

of

lung

parenchyma

was

independently

rated

using

a

two-point

scale

adapted

from

a

previous

publication

-LSB-

-RSB-

Lung

parenchyma

allowing

diagnostic

assessment

due

to

distinct

anatomic

details

of

bronchial

and

parenchymal

structures

without

significant

artifacts

and

noise

was

rated

with

a

score

of

-LRB-

diagnostic

-RRB-

Lung

parenchyma

with

artifacts

or

noise

causing

reduction

of

image

quality

and

diagnostic

value

was

rated

with

a

score

of

-LRB-

non-diagnostic

-RRB-

Artifacts

were

rated

to

quantify

the

cranio-caudal

distribution

of

artifacts

within

the

lung

parenchyma

for

the

right

and

left

lung

separately

in

coronal

MPR

Because

of

the

different

tube

current

at

upper

and

lower

parts

along

the

z-axis

-LRB-

see

Fig.

-RRB-

the

following

scores

were

separately

applied

for

the

apex

and

the

basis

of

the

lung

respectively

no

artifacts

breathing

artifacts

-LRB-

stair

step

artifacts

-RRB-

ECG-gating

-LRB-

i.e.

synchronization

or

interpolation

artifacts

-RRB-

and

noise

artifacts

If

breathing

and

ECG-gating

artifacts

appeared

at

the

same

time

in

one

patient

the

artifact

with

the

worst

impact

on

image

quality

was

noted

Image

quality

and

artifacts-vascular

structures

Image

quality

of

thoracic

vascular

structures

was

independently

rated

using

the

same

two-point

scale

-LSB-

-RSB-

as

used

for

the

rating

of

the

lung

parenchyma

Regarding

the

thoracic

aorta

a

score

of

-LRB-

diagnostic

-RRB-

indicated

confident

evaluation

of

the

ascending

aorta

the

aortic

arch

and

descending

aorta

Regarding

pulmonary

arteries

a

score

of

indicated

confident

evaluation

of

central

lobar

segmental

or

subsegmental

pulmonary

arteries

Regarding

coronary

arteries

a

score

of

represented

confident

depiction

-LRB-

homogenous

attenuation

no

artifacts

decreasing

coronary

analysis

-RRB-

of

the

right

coronary

artery

-LRB-

RCA

-RRB-

left

main

artery

-LRB-

LMA

-RRB-

left

anterior

descending

artery

-LRB-

LAD

-RRB-

left

circumflex

artery

-LRB-

LCX

-RRB-

and

their

side

branches

A

score

of

indicated

decreased

image

quality

of

thoracic

vascular

structures

with

severe

impairment

of

diagnostic

value

-LRB-

non-diagnostic

-RRB-

due

to

breathing

motion

or

ECG-gating

artifacts

Image

noise

and

attenuation-vascular

structures

Image

noise

was

determined

as

the

standard

deviation

of

attenuation

in

a

ROI

placed

in

the

ascending

aorta

-LSB-

-RSB-

Contrast

attenuation

was

measured

in

each

patient

in

the

ascending

aorta

pulmonary

trunk

LMA

proximal

segment

of

the

RCA

and

right

and

left

ventricle

Image

noise

and

contrast

attenuation

were

assessed

using

a

circular

ROI

positioned

exactly

within

the

vessel

or

ventricular

lumen

while

avoiding

superimposition

or

partial

volume

effects

from

the

vessel

wall

or

myocardium

Measurements

of

the

ascending

aorta

and

pulmonary

trunk

as

well

as

of

the

right

and

left

ventricle

were

performed

on

the

same

transverse

image

while

the

ROI

in

the

coronary

arteries

was

individually

placed

on

separate

transverse

images

Imaging

findings

Imaging

findings

indicating

the

possible

underlying

cause

of

acute

chest

pain

were

documented

in

each

patient

by

both

readers

in

consensus

Statistical

analysis

Statistical

analysis

was

performed

using

commercially

available

software

-LRB-

SPSS

SPSS

Inc.

Il

-RRB-

Quantitative

variables

are

expressed

as

mean

standard

deviation

-LRB-

SD

-RRB-

including

confidence

intervals

-LRB-

CI

-RRB-

or

range

when

appropriate

Categorical

data

were

expressed

as

frequencies

or

percentages

Inter-observer

agreement

-LRB-

kappa

statistics

-RRB-

for

image

quality

ratings

was

calculated

Two-tailed

Student

's

t

test

for

paired

samples

was

used

to

explore

significant

differences

in

vessel

attenuation

among

the

ascending

aorta

RCA

LMA

pulmonary

trunk

and

right

and

left

ventricle

Intra-individual

differences

regarding

vessel

attenuation

among

the

different

vascular

territories

were

performed

using

pairwise

comparisons

Bonferroni

correction

for

multiple

comparisons

was

made

and

a

P-value

was

considered

statistically

significant

Results

All

CT

scans

were

well

tolerated

and

were

successfully

performed

in

all

patients

without

complications

All

patients

had

a

sinus

rhythm

and

the

average

heart

rate

during

data

acquisition

was

beats

per

minute

-LRB-

bpm

-RRB-

-LRB-

range

bpm

-RRB-

No

beta

receptor

antagonists

or

benzodiazepines

were

administered

prior

to

CT

patients

-LRB-

-RRB-

took

oral

beta

blockers

as

part

of

their

baseline

medication

at

the

time

of

the

scan

Mean

scan

time

was

s

-LRB-

range

s

-RRB-

and

mean

scan

length

was

cm

-LRB-

range

cm

-RRB-

The

reconstruction

interval

used

for

image

reading

was

of

the

R-R

interval

In

seven

patients

it

was

considered

necessary

to

reconstruct

additional

data

sets

in

intervals

within

the

window

of

full

tube

current

to

obtain

images

with

diagnostic

quality

Image

quality

and

artifacts-lung

parenchyma

Image

quality

of

lung

parenchyma

was

rated

as

being

diagnostic

-LRB-

score

-RRB-

by

both

readers

in

all

patients

-LRB-

excellent

inter-observer

agreement

kappa

-RRB-

and

pathology

both

at

upper

and

lower

lung

parts

could

be

diagnosed

or

excluded

in

all

patients

Lung

parenchyma

was

rated

by

both

readers

as

being

artifact-free

in

patients

-LRB-

-RRB-

Breathing

artifacts

causing

stair-step

artifacts

were

encountered

in

nine

patients

-LRB-

-RRB-

by

one

reader

and

eight

-LRB-

-RRB-

of

these

nine

patients

by

the

other

reader

-LRB-

excellent

inter-observer

agreement

kappa

-RRB-

Breathing

artifacts

were

exclusively

found

at

the

lung

base

i.e.

at

the

end

of

the

breath-hold

period

ECG-gating-related

artifacts

were

found

in

ten

patients

-LRB-

-RRB-

by

one

reader

and

in

nine

-LRB-

-RRB-

of

these

ten

patients

by

the

other

reader

-LRB-

excellent

inter-observer

agreement

kappa

-RRB-

The

two

types

of

artifacts

were

not

encountered

in

the

same

patient

and

image

quality

was

diagnostic

despite

the

artifacts

Image

quality

and

artifacts-vascular

structures

Image

quality

of

the

thoracic

aorta

was

rated

by

both

readers

as

being

diagnostic

-LRB-

score

-RRB-

in

all

patients

-LRB-

excellent

inter-observer

agreement

kappa

-RRB-

and

pathologies

of

the

thoracic

aorta

could

be

diagnosed

or

excluded

by

both

readers

in

all

patients

Both

readers

rated

image

quality

of

the

pulmonary

arteries

in

the

one

-LRB-

i.e.

the

same

-RRB-

patient

-LRB-

-RRB-

as

being

non-diagnostic

-LRB-

score

-RRB-

due

to

insufficient

attenuation

of

segmental

and

subsegmental

pulmonary

arteries

In

this

patient

attenuation

did

not

allow

excluding

segmental

or

subsegmental

pulmonary

embolism

while

attenuation

in

the

pulmonary

trunk

and

right

and

left

lobar

artery

was

considered

sufficient

for

diagnosis

or

exclusion

of

central

and

lobar

pulmonary

embolism

In

this

patient

image

quality

of

the

coronary

arteries

was

considered

as

being

diagnostic

by

both

readers

Image

quality

of

coronary

arteries

was

rated

by

both

readers

as

being

diagnostic

-LRB-

score

-RRB-

in

the

same

patients

-LRB-

excellent

inter-observer

agreement

kappa

-RRB-

In

the

remaining

two

patients

-LRB-

-RRB-

image

quality

of

the

coronary

arteries

was

considered

by

both

readers

as

being

non-diagnostic

-LRB-

score

-RRB-

due

to

ECG-gating-related

artifacts

-LRB-

mean

heart

rate

bpm

ranging

from

to

bpm

during

scanning

-RRB-

in

one

and

severe

image

noise

due

to

obesity

-LRB-

body

mass

index

-RRB-

in

the

other

In

both

patients

both

readers

rated

image

quality

of

the

pulmonary

arteries

as

being

diagnostic

Image

noise

and

attenuation-vascular

structures

Mean

image

noise

in

the

ascending

aorta

-LRB-

mean

ROI

size

-RRB-

was

Mean

attenuation

in

the

ascending

aorta

-LRB-

same

ROI

and

same

ROI

size

as

for

measurements

of

image

noise

-RRB-

was

HU

-LRB-

CI

HU

-RRB-

mean

attenuation

in

the

pulmonary

trunk

-LRB-

mean

ROI

size

-RRB-

was

HU

-LRB-

CI

HU

-RRB-

mean

attenuation

in

the

proximal

RCA

-LRB-

mean

ROI

size

-RRB-

was

HU

-LRB-

CI

HU

-RRB-

and

mean

attenuation

in

the

LMA

-LRB-

mean

ROI

size

-RRB-

was

HU

-LRB-

CI

HU

-RRB-

Mean

attenuation

in

the

right

ventricle

-LRB-

mean

ROI

size

-RRB-

was

HU

-LRB-

CI

HU

-RRB-

and

mean

attenuation

in

the

left

ventricle

-LRB-

mean

ROI

size

-RRB-

was

HU

-LRB-

CI

HU

-RRB-

-LRB-

Fig.

-RRB-

Fig.

attenuation

values

-LRB-

HU

-RRB-

within

different

vessels

indicating

a

relatively

homogenous

contrast

distribution

between

the

different

thoracic

vascular

territories

RCA

right

coronary

artery

LMA

left

main

coronary

artery

No

significant

differences

regarding

attenuation

were

found

between

the

RCA

and

LMA

-LRB-

P

n.s.

-RRB-

and

between

the

ascending

aorta

and

both

coronary

arteries

-LRB-

P

n.s.

-RRB-

No

significant

differences

in

attenuation

were

present

between

the

right

and

left

ventricle

-LRB-

P

n.s.

-RRB-

between

the

right

ventricle

and

ascending

aorta

-LRB-

P

n.s.

-RRB-

between

the

right

ventricle

and

pulmonary

trunk

-LRB-

P

n.s.

-RRB-

and

between

the

right

ventricle

and

the

RCA

-LRB-

P

n.s.

-RRB-

and

LMA

-LRB-

P

n.s.

-RRB-

Similarly

there

were

no

significant

differences

in

attenuation

between

the

left

ventricle

and

ascending

aorta

-LRB-

P

n.s.

-RRB-

and

between

left

ventricle

and

LMA

-LRB-

P

n.s.

-RRB-

and

RCA

-LRB-

P

n.s.

-RRB-

Significant

differences

were

only

found

between

the

pulmonary

trunk

and

ascending

aorta

-LRB-

P

-RRB-

between

the

pulmonary

trunk

and

the

RCA

and

LMA

-LRB-

P

-RRB-

respectively

and

between

the

left

ventricle

and

pulmonary

trunk

-LRB-

P

-RRB-

Pairwise

comparisons

of

mean

intra-individual

differences

regarding

vessel

attenuation

were

small

and

ranged

between

HU

comparing

the

right

and

left

coronary

artery

and

HU

comparing

the

pulmonary

trunk

and

left

ventricle

-LRB-

Table

-RRB-

Table

intra-individual

comparisons

between

different

thoracic

vascular

territories

Mean

differenceStandard

confidence

intervalLower

boundaryUpper

boundaryAortaPulmonary

trunk-4311-75-11AortaRCA65-1022AortaLCA54-817AortaRight

trunkRight

trunkLeft

right

coronary

artery

LCA

left

coronary

artery

Imaging

findings

No

pathologic

findings

were

found

in

patients

-LRB-

-RRB-

whereas

various

pathologies

of

the

aorta

pulmonary

and

coronary

arteries

lung

and

mediastinum

were

present

in

patients

-LRB-

-RRB-

-LRB-

Table

Figs.

-RRB-

Table

findings

in

the

study

populationDiagnosisNumber

of

patients

-LRB-

n

-RRB-

No

pathology

Dissection

type

Pseudoaneurysm

of

the

aortic

Plaque

pathology

Significant

stenosis

of

the

Occlusion

of

the

cell

lung

cell

left

anterior

descending

artery

RCA

right

coronary

arteryFig

female

patient

admitted

to

the

emergency

department

with

acute

chest

pain

-LRB-

a

-RRB-

Curved

multiplanar

reformations

along

the

centerline

of

the

right

coronary

-LRB-

RCA

-RRB-

left

anterior

descending

-LRB-

LAD

-RRB-

and

the

left

circumflex

artery

-LRB-

RCX

-RRB-

allow

excluding

significant

coronary

stenosis

in

this

patient

Mean

heart

rate

during

DSCTA

was

bpm

-LRB-

b

-RRB-

Thin-slab

transverse

maximum

intensity

projection

shows

no

evidence

of

pulmonary

embolism

-LRB-

c

-RRB-

Transverse

image

at

the

level

of

the

pulmonary

trunk

demonstrates

acute

aortic

dissection

type

B

-LRB-

arrow

-RRB-

with

mild

left-sided

pleural

effusionFig

female

patient

admitted

to

the

emergency

department

with

acute

chest

pain

-LRB-

a

-RRB-

Curved

multiplanar

reformations

along

the

centerline

of

the

right

coronary

-LRB-

RCA

-RRB-

left

anterior

descending

-LRB-

LAD

-RRB-

and

the

left

circumflex

artery

-LRB-

LCX

-RRB-

demonstrate

normal

coronary

arteries

and

no

evidence

of

stenosis

Mean

heart

rate

during

DSCTA

was

bpm

-LRB-

b

-RRB-

Thin-slab

transverse

maximum

intensity

projection

show

bilateral

pulmonary

embolism

-LRB-

arrows

-RRB-

-LRB-

c

-RRB-

Oblique-sagittal

thin-slab

maximum

intensity

projection

demonstrates

the

thoracic

aorta

without

evidence

of

diseaseFig

male

patient

admitted

to

the

emergency

department

with

acute

chest

pain

-LRB-

a

-RRB-

Curved

multiplanar

reformations

along

the

centerline

of

the

right

coronary

-LRB-

RCA

-RRB-

left

anterior

descending

-LRB-

LAD

-RRB-

and

the

left

circumflex

artery

-LRB-

LCX

-RRB-

show

occlusion

of

the

proximal

RCA

-LRB-

long

arrow

-RRB-

and

vessel

wall

calcifications

without

significant

stenosis

in

the

proximal

and

middle

segment

of

the

LAD

and

LCX

-LRB-

short

arrows

-RRB-

Mean

heart

rate

during

DSCTA

was

bpm

-LRB-

b

-RRB-

Thin-slab

transverse

maximum

intensity

projection

demonstrates

normal

opacification

of

pulmonary

arteries

with

no

evidence

of

embolism

-LRB-

c

-RRB-

Oblique-sagittal

thin-slab

maximum

intensity

projection

demonstrates

the

thoracic

aorta

with

minimal

atherosclerotic

wall

changes

but

with

no

evidence

of

potential

causes

for

acute

chest

pain

Discussion

Our

study

demonstrates

that

DSCT

allows

performing

an

ECG-gated

chest

examination

for

visualizing

the

different

thoracic

vascular

territories

at

the

same

time-by

employing

an

adjusted

contrast

media

protocol-within

a

reasonable

breath-hold

period

and

thus

provides

a

diagnostic

image

quality

in

almost

all

patients

One

of

the

most

important

findings

of

this

study

is

that

diagnostic

data

of

coronary

arteries

could

be

obtained

without

foregoing

heart

rate

control

Contrast

media

protocol

and

scan

time

With

increasing

gantry

rotation

times

and

faster

volume

coverage

of

newer

CT

scanners

scan

times

successively

shorten

and

higher

injection

rates

are

required

to

achieve

sufficient

contrast

in

the

vascular

territory

of

interest

Similar

to

a

previous

CT

study

-LSB-

-RSB-

we

have

set

the

ROI

for

bolus

tracking

in

the

ascending

aorta

With

a

relatively

low

threshold

of

HU

above

which

the

scan

was

initiated

a

homogenous

attenuation

in

both

aortic/coronary

and

pulmonary

arteries

could

be

achieved

By

doing

so

we

aimed

at

the

time

interval

where

the

contrast

enhancement

curve

of

the

pulmonary

circulation

overlaps

with

enhancement

of

the

aorta

-LSB-

-RSB-

This

has

also

resulted

in

comparable

attenuation

in

left

and

right

cardiac

cavities

Recommended

mean

attenuation

values

for

diagnostic

image

quality

are

approximately

HU

for

the

pulmonary

arteries

-LSB-

-RSB-

and

HU

in

the

ascending

aorta

and

coronary

arteries

-LSB-

-RSB-

We

obtained

a

mean

attenuation

of

HU

in

the

ascending

aorta

HU

in

the

pulmonary

trunk

HU

in

the

RCA

and

HU

in

the

LMA

with

only

small

intra

and

inter-individual

variations

These

attenuation

values

were

considered

diagnostic

in

of

our

patients

and

are

comparable

to

previously

published

data

-LSB-

-RSB-

We

encountered

only

one

patient

with

non-diagnostic

attenuation

of

segmental

and

subsegmental

pulmonary

arteries

However

this

may

have

been

also

caused

by

other

reasons

negatively

affecting

contrast

attenuation

in

pulmonary

arteries

such

as

Valsalva

maneuver

-LSB-

-RSB-

The

other

major

issue

for

CT

in

acute

chest

pain

represents

the

issue

of

scan

duration

As

ECG-gated

CT

requires

low

pitch

-LSB-

-RSB-

scan

time

is

increased

as

compared

to

non-gated

chest

CT

examinations

This

however

negatively

affects

image

quality

by

making

examinations

more

prone

to

breathing

artifacts

This

holds

particularly

true

for

patients

with

acute

chest

pain

who

often

suffer

from

dyspnea

In

our

study

mean

scan

time

was

approximately

s

which

represents

a

further

improvement

as

compared

to

a

mean

scan

time

of

s

with

CT

-LSB-

-RSB-

Role

of

CT

in

the

diagnostic

pathway

of

acute

chest

pain

Figure

represents

a

simplified

flow-chart

of

a

generally

accepted

clinical

pathway

for

patients

with

cardiac

and

non-cardiac

causes

of

acute

chest

pain

-LSB-

-RSB-

While

CT

is

the

accepted

reference

modality

for

the

diagnosis

and

exclusion

of

pulmonary

embolism

and

aortic

dissection

-LSB-

-RSB-

the

role

of

CT

in

patients

with

a

suspected

cardiac

cause

for

chest

pain

is

currently

under

investigation

Gallagher

and

colleagues

-LSB-

-RSB-

have

shown

that

CT

has

accuracy

that

is

comparable

to

that

of

stress

nuclear

imaging

for

the

detection

of

acute

coronary

syndrome

in

low-risk

patients

with

negative

serial

ECG

and

biomarker

results

Hoffmann

and

coworkers

-LSB-

-RSB-

have

demonstrated

that

CT

has

good

performance

characteristics

for

ruling

out

acute

coronary

syndromes

in

patients

presenting

to

the

emergency

department

with

acute

chest

pain

The

authors

demonstrated

in

patients

in

whom

initial

triage

was

inconclusive

that

the

absence

of

coronary

artery

plaque

or

significant

stenosis

on

CT

angiography

had

an

excellent

negative

predictive

value

for

the

subsequent

diagnosis

of

acute

coronary

syndrome

Furthermore

in

those

patients

with

CAD

on

CT

the

extent

of

coronary

atherosclerotic

plaque

provided

incremental

information

to

standard

baseline

patient

variables

and

clinical

risk

assessment

Goldstein

and

colleagues

-LSB-

-RSB-

have

shown

that

CT

coronary

angiography

is

able

to

definitely

establish

or

exclude

CAD

as

the

cause

of

acute

chest

pain

The

high

negative

predictive

value

of

the

studies

suggests

that

CT

coronary

angiography

may

be

useful

for

facilitating

and

optimizing

triage

of

patients

with

acute

chest

pain

and/or

inconclusive

initial

emergency

department

evaluation

-LSB-

-RSB-

Fig.

chart

of

a

generally

accepted

clinical

pathway

for

patients

with

cardiac

and

non-cardiac

causes

of

acute

chest

pain

CT

represents

the

standard

of

reference

in

patients

with

suspicion

of

acute

aortic

syndromes

or

pulmonary

embolism

-LRB-

light

gray

boxes

-RRB-

The

added

value

of

CT

in

the

evaluation

of

acute

coronary

syndrome

has

been

already

demonstrated

-LSB-

-RSB-

-LRB-

moderate

gray

box

-RRB-

The

potential

future

role

of

CT

in

patients

with

acute

chest

pain

might

be

at

an

even

earlier

point

of

diagnostic

work-up

-LRB-

dark

gray

boxes

-RRB-

to

rule

out

life-threatening

coronary

pulmonary

and

aortic

disease

and

to

guide

adequate

therapeutic

interventions

Study

limitations

We

included

only

a

relatively

small

number

of

patients

and

thus

a

small

number

of

pathologies

Second

our

study

lacks

a

standard

end-point

to

assess

the

final

diagnosis

and

misses

comparison

with

the

reference

standard

invasive

coronary

angiography

for

investigating

CAD

for

which

diagnostic

accuracy

could

be

calculated

However

only

a

minority

of

our

patients

underwent

invasive

coronary

angiography

because

in

our

emergency

department

standard

management

in

patients

with

suspected

acute

coronary

syndrome

directly

undergoing

invasive

coronary

angiography

without

prior

CT.

That

is

in

line

with

most

studies

involving

patients

referred

to

the

emergency

department

-LSB-

-RSB-

Third

we

did

not

investigate

the

optimal

contrast

media

technique

for

obtaining

homogenous

contrast

attenuation

of

different

thoracic

vascular

territories

It

remains

to

be

determined

if

the

use

of

the

test

bolus

technique

would

yield

better

results

with

regard

to

vessel

opacification

Finally

it

needs

to

be

assessed

whether

caudo-cranial

or

caudo-cranial

scan

direction

will

result

in

better

image

quality

Conclusion

First

experience

indicates

that

DSCTA

is

feasible

in

patients

with

acute

chest

pain

and

provides

diagnostic

image

quality

of

the

aorta

pulmonary

arteries

and

coronary

artery

system

as

well

as

of

the

lung

parenchyma

and

mediastinum

in

a

patient

population

without

foregoing

heart

rate

control

A

dedicated

contrast

media

protocol

allows

for

homogenous

attenuation

of

the

different

thoracic

vascular

territories

O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O B I I O O O O O O O O O O O O B I O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Risk factors for severe RSV-induced lower respiratory tract infection over four consecutive epidemics Variability in severity among different respiratory syncytial virus -LRB- RSV -RRB- seasons may influence hospital admission rates for RSV-induced lower respiratory tract infection -LRB- LRTI -RRB- in young children . The aim of the present study was to identify through logistic regression analysis , risk factors associated with higher likelihood to acquire RSV-induced LRTI , in children with symptoms severe enough to lead to hospital admission . Over four consecutive RSV seasons -LRB- 2000 -- 2004 -RRB- , records from children < 4 years of age admitted for RSV-induced LRTI -LRB- `` cases '' -RRB- were compared with those from children with LRTI not due to RSV and not requiring hospitalization -LRB- `` controls '' -RRB- . 145 `` case-patients '' and 295 `` control-patients '' were evaluated . Independent from the severity of the four epidemic seasons , seven predictors for hospitalization for RSV infection were found in the bivariate analysis : number of children in the family , chronological age at the onset of RSV season , birth weight and gestational age , birth order , daycare attendance , previous RSV infections . In the logistic regression analysis , only three predictors were detected : chronological age at the beginning of RSV season -LSB- aOR = 8.46 ; 95 % CI : 3.09 -- 23.18 -RSB- ; birth weight category -LSB- aOR = 7.70 ; 95 % CI : 1.29 -- 45.91 -RSB- ; birth order -LRB- aOR = 1.92 ; 95 % CI : 1.21 -- 3.06 -RRB- . Conclusions : Independent from the RSV seasonality , specific host/environmental factors can be used to identify children at greatest risk for hospitalization for RSV infection . Introduction Lower respiratory tract infection -LRB- LRTI -RRB- due to respiratory syncytial virus -LRB- RSV -RRB- is a major cause of morbidity in infants and young children -LSB- 21 -RSB- . Although certain risk factors have been traditionally associated with a higher likelihood to develop severe RSV-induced LRTI , the vast majority of children hospitalized for this condition are previously normal babies -LSB- 3 , 21 -RSB- . Solid epidemiologic data indicate that prematurity is a consistently proven risk factor for severe LTRI induced by RSV -LSB- 3 , 21 -RSB- . However , there are other independent risk factors , which show a significant variability among studies performed in different countries and even among different RSV seasons within the same country with alternation of minor and major epidemics -LSB- 1 , 3 , 4 , 21 -RSB- . This was recently demonstrated in the `` Osservatorio study '' , which was designed to collect epidemiological data on RSV infection in two consecutive winter epidemics -LRB- 2000 -- 2002 -RRB- in Italy -LSB- 16 -RSB- . This study showed that , because of differences in severity of the two RSV seasons , some of the risk factors were significant in one but not in the subsequent epidemics -LSB- 15 -RSB- . To further expand the RSV surveillance , the `` Osservatorio study '' was extended for two additional winter epidemics -LRB- 2002 -- 2004 -RRB- . The aim of the present study was to use the data collected to identify , by means of logistic regression analysis , risk factors associated with higher likelihood to acquire RSV-induced LRTI in children with symptoms severe enough to lead to hospital admission . Materials and methods Study design A case-control study was used to evaluate the risk factors associated with higher likelihood to acquire RSV-induced LRTI , severe enough to lead to hospital admission , over four consecutive winter epidemics in Italy -LRB- 2000 -- 2004 -RRB- . The pediatric centres involved -LRB- scattered over the Italian national territory -RRB- , the study population , the surveillance , and the laboratory methods have been described elsewhere -LSB- 13 -RSB- . Briefly , all consecutive children , aged ≤ 4 years , referred to emergency departments for acute respiratory infection on one day of the week -LRB- Tuesday -RRB- , between 8 a.m. and 2 p.m. , during the `` expected '' epidemiological seasons -LRB- October -- April -RRB- were enrolled and tested for RSV determination . Children who had received immunoprophylaxis with palivizumab -LRB- ≤ 7 , each year -RRB- were excluded . We expanded the age limit of the children to be enrolled over the `` classic '' 24 months , to also evaluate possible predictors of RSV-induced LRTI in an older age group . Each study site determined the date of onset and the end of the local RSV season according to a definition previously developed by the Pediatric Investigators Collaborative Network on Infections in Canada -LRB- PICNIC -RRB- group -LSB- 20 -RSB- . The study protocol was approved by the local ethics board of each hospital and written informed consent was sought from parents or guardians of all children evaluated . Medical history and physical examination were recorded and evaluated and clinical assessment , including nasal secretion specimens for RSV detection , were obtained according to the usual protocol at each hospital . Nasal secretion samples were sent to the microbiology laboratory of each hospital to check for RSV by an immunoenzymatic test -LRB- TestPack RSV , Abbott , Italy -RRB- within 24 hours . Other respiratory viruses were not tested . All children were treated according to standardized protocols and the decision to admit a child to hospital for a respiratory illness was made by local non-study physicians responsible for each child 's care and was not influenced by the child 's participation in the study . Case definition and control selection During a given study year , children were considered eligible for the case-control study on the base of his/her first LRTI during that year . `` Case of disease '' was defined as LRTI due to RSV , occurring in a child ≤ 4 years of age and requiring hospital admission . From the cases we excluded patients with LRTI induced by agents other than RSV or RSV-positive but not severe enough to require hospitalization . `` Controls '' were selected from children who had LRTI which was with certainty not due to RSV -LRB- negativity on immunoenzymatic test performed on nasal secretions -RRB- and who did not require hospitalization . This control population was selected to determine both predictors of acquiring RSV infection and developing severe disease . All controls should have come from the same residence areas as case-patients . Since case patients ranged from 0 to 30 months of age , control patients aged ≥ 31 months were excluded from the total control population -LRB- N = 1064 -RRB- . Within the remaining group of controls -LRB- N = 729 -RRB- , a sample -LRB- N = 295 -RRB- was randomly selected -LRB- simple random selection procedure via SPSS software -RRB- and included in the study to obtain a case-control ratio of 1:2 . For both case patients and controls evaluated in the four epidemic seasons , data related to the characteristics of the family -LRB- e.g. mother 's age , number of children in the family , father 's and mother 's educational level and social condition score -RRB- and of the children -LRB- e.g. chronological age of the child at the beginning of RSV season , birth weight , birth order , gestational age , length of breast feeding -RRB- were categorized according to cut-offs partially derived from literature -LSB- 5 , 10 , 12 -RSB- and partially imposed from the original categorization recorded in the `` Osservatorio '' database . In addition , children were considered to be small for gestational age -LRB- SGA -RRB- if their weight at birth fell below the 10th percentile based on gestational age and sex according to Oken 's method -LSB- 15 -RSB- and using the United States of America national reference . Statistical analysis and data definitions Descriptive statistics of the characteristics of the patients were performed and reported in terms of mean and standard deviation -LRB- SD -RRB- for the quantitative variables -LRB- chronological age , birth weight , gestational age , etc. -RRB- and in terms of absolute frequencies and percentages for the qualitative variables . Firstly , a bivariate analysis was performed and the comparison of quantitative variables between two groups of subjects -LRB- i.e. cases vs controls -RRB- was made calculating the likelihood ratio test -LRB- LR test -RRB- , and reporting the bivariate odds ratio -LRB- OR -RRB- and 95 % confidence interval -LRB- CI -RRB- . Comparison of frequency data was performed by the chi-square test or by the Fisher 's exact test in case of expected frequencies less than five . In order to evaluate the role of different predictors in the association with the outcome -LRB- hospitalization for RSV infection -RRB- , multiple logistic regression analysis -LRB- step-down strategy -RRB- was performed . Variables that were statistically significant in the bivariate analysis or that were considered a priori important for the outcome were entered in the model . The following predictors were considered : epidemic season , father 's educational level , chronological age category at the beginning of RSV season , birth order , birth weight category , small for gestational age , daycare attendance , and previous RSV infections . The effect was expressed in terms of adjusted -LRB- a -RRB- OR and 95 % CI and the LR test was performed . The models ' predictive ability has been investigated by calculating the area under the ROC curve of the model -LRB- AUC -RRB- . All tests were two-sided and a P value less than 0.05 was considered statistically significant . The statistical packages used were the `` Statistica release 6 '' -LRB- StatSoft Corp. , Tulsa , OK , USA -RRB- for bivariate analyses and the `` Stata release 7 '' -LRB- Stata Corporation , College Station , TX , USA -RRB- for multivariate analyses . Results Patient populations There were 145 case-patients included in the study -LRB- plus three cases not evaluated because of missing values -RRB- . There were 61 males -LRB- 42.1 % -RRB- and 84 females -LRB- 57.9 % -RRB- , with a median age of 3.5 months and a median birth weight of 3,050 grams . Seventeen of the 145 -LRB- 11.7 % -RRB- were born preterm -LRB- at less than 36 weeks of gestational age -RRB- , two had congenital heart conditions and five had a previous history of chronic lung disease . There were 292 control-patients -LRB- plus three cases not evaluated because of missing values -RRB- . There were 124 males -LRB- 42.5 % -RRB- and 168 females -LRB- 57.5 % -RRB- , with a median age of 5 months . Eighteen were preterm infants -LRB- 6.2 % -RRB- and their birth weight was greater but not significantly different -LRB- mean = 2,310 ; median = 2,175 grams -RRB- from the preterm case-patients ' birth weight -LRB- mean = 1,993 ; median = 1,817.5 -RRB- -LRB- P = 0.21 -RRB- . Risk factors associated with a higher likelihood to acquire RSV-induced LRTI , severe enough to lead to hospital admission In the bivariate analysis we considered several risk factors that could be associated with a higher likelihood to acquire RSV-induced LRTI , severe enough to lead to hospital admission . In Table 1 only the statistically significant risk factors associated with a higher likelihood to acquire RSV-induced LRTI , severe enough to lead to hospital admission , are reported . The bivariate analysis showed that , although the severity of RSV-induced LRTI with hospital admission was different during the four epidemics , a variety of other risk factors could be detected . The only demographic-social characteristic associated with severe RSV-induced LRTI requiring hospitalization was the number of children in the family ≥ 2 . Geographical area , social condition level and mother 's age category were not significant risk factors -LRB- not shown -RRB- . The major predictors were the characteristics of the child itself as follows : low chronological age at the beginning of RSV season , being at least the second baby in the family , having a low birth weight -LRB- 1,500 -- 2,499 g -RRB- , and a low gestational age -LRB- < 33 weeks -RRB- . In addition , the absence of daycare attendance was also a risk factor and higher risks could be seen in children without previous exposure to RSV infections . Having a birth weight small for the gestational age was also a risk factor but the role of the birth weight uncorrected for gestational age was a stronger predictor . Breast feeding had no significant role due to the small number of data available -LRB- n = 138 -RRB- . Mother 's educational level was available only in a very small subset of patients -LRB- n = 80 -RRB- -LRB- not shown -RRB- and because of the strong association with father 's educational level -LRB- not shown -RRB- -LRB- P < 0.0001 -RRB- only this latter variable was considered in subsequent analysis . Table 1Distribution of risk factors associated with a higher likelihood to acquire RSV-induced LRTI , severe enough to lead to hospital admission Cases -LRB- N = 145 -RRB- N -LRB- % -RRB- Controls -LRB- N = 292 -RRB- N -LRB- % -RRB- P valueOR -LRB- 95 % CI -RRB- Epidemic season 2003 -- 200429 -LRB- 20.0 % -RRB- 56 -LRB- 19.2 % -RRB- Reference 2002 -- 200350 -LRB- 34.5 % -RRB- 68 -LRB- 23.3 % -RRB- 1.42 -LRB- 0.80 -- 2.53 -RRB- 2001 -- 200241 -LRB- 28.3 % -RRB- 122 -LRB- 41.8 % -RRB- 0.65 -LRB- 0.37 -- 1 -- 15 -RRB- 2000 -- 200125 -LRB- 17.2 % -RRB- 46 -LRB- 15.7 % -RRB- P = 0.0241.05 -LRB- 0.54 -- 2.03 -RRB- Epidemic period -LRB- October to April -RRB- : Yes137 -LRB- 94.6 % -RRB- 247 -LRB- 84.6 % -RRB- P = 0.0033.12 -LRB- 1.43 -- 6.81 -RRB- Sex : Female84 -LRB- 57.9 % -RRB- 168 -LRB- 57.5 % -RRB- P = 0.941.02 -LRB- 0.68 -- 1.52 -RRB- Exposure to cigarette smoking : Yes -LRB- N = 432 -RRB- 74 -LRB- 51.7 % -RRB- 165 -LRB- 57.1 % -RRB- P = 0.290.81 -LRB- 0.54 -- 1.21 -RRB- Family history of allergy : Yes -LRB- N = 333 -RRB- 50 -LRB- 44.6 % -RRB- 75 -LRB- 33.9 % -RRB- P = 0.061.57 -LRB- 0.99 -- 2.50 -RRB- No . of children in the family : ≥ 2 -LRB- N = 393 -RRB- 97 -LRB- 72.9 % -RRB- 155 -LRB- 59.6 % -RRB- P = 0.0091.83 -LRB- 1.16 -- 2.88 -RRB- Chronological age at the beginning of RSV season ≥ 12 months6 -LRB- 4.1 % -RRB- 48 -LRB- 16.4 % -RRB- P < 0.0001 Reference 6 -- 11 months31 -LRB- 21.4 % -RRB- 98 -LRB- 33.6 % -RRB- 2.53 -LRB- 0.99 -- 6.48 -RRB- 3 -- 5 months48 -LRB- 33.1 % -RRB- 85 -LRB- 29.1 % -RRB- 4.52 -LRB- 1.80 -- 11.33 -RRB- < 3 months60 -LRB- 41.4 % -RRB- 61 -LRB- 20.9 % -RRB- 7.87 -LRB- 3.13 -- 19.75 -RRB- Birth order : ≥ 2nd -LRB- N = 420 -RRB- 95 -LRB- 69.3 % -RRB- 151 -LRB- 53.4 % -RRB- P = 0.0021.98 -LRB- 1.28 -- 3.05 -RRB- Birth weight category -LRB- N = 430 -RRB- ≥ 2500 grams113 -LRB- 80.1 % -RRB- 259 -LRB- 92.2 % -RRB- P = 0.013 aReference 1500 -- 2499 grams24 -LRB- 17.0 % -RRB- 28 -LRB- 7.2 % -RRB- 1.96 -LRB- 1.09 -- 3.54 -RRB- < 1500 grams4 -LRB- 2.8 % -RRB- 2 -LRB- 0.6 % -RRB- 4.58 -LRB- 0.83 -- 25.39 -RRB- Gestational age category -LRB- N = 430 -RRB- ≥ 36 weeks126 -LRB- 88.1 % -RRB- 269 -LRB- 93.7 % -RRB- P = 0.023 aReference 33 -- 35 weeks8 -LRB- 5.6 % -RRB- 14 -LRB- 4.9 % -RRB- 1.22 -LRB- 0.50 -- 2.98 -RRB- < 33 weeks9 -LRB- 6.3 % -RRB- 4 -LRB- 1.4 % -RRB- 5.35 -LRB- 1.45 -- 15.89 -RRB- SGA : Yes -LRB- N = 426 -RRB- 36 -LRB- 25.7 % -RRB- 63 -LRB- 22.0 % -RRB- P = 0.401.23 -LRB- 0.76 -- 1.96 -RRB- Breast feeding -LRB- N = 138 -RRB- None or < 3 months25 -LRB- 71.4 % -RRB- 68 -LRB- 66.0 % -RRB- P = 0.14 aReference 3 -- 6 months9 -LRB- 25.7 % -RRB- 20 -LRB- 19.4 % -RRB- 1.22 -LRB- 0.49 -- 3.04 -RRB- ≥ 7 months1 -LRB- 2.9 % -RRB- 15 -LRB- 14.6 % -RRB- 0.18 -LRB- 0.02 -- 1.44 -RRB- Daycare attendance : No -LRB- N = 430 -RRB- 138 -LRB- 97.9 % -RRB- 265 -LRB- 78.0 % -RRB- P = 0.0134.17 -LRB- 1.23 -- 14.08 -RRB- Previous RSV infections : No -LRB- N = 426 -RRB- 126 -LRB- 88.7 % -RRB- 230 -LRB- 81.0 % -RRB- P = 0.0421.85 -LRB- 1.02 -- 3.36 -RRB- P values in the table refer to chi-square test , unless otherwise specifieda Fisher 's exact test In the logistic regression analysis variables that were statistically significant in the bivariate analysis or that were considered a priori important for the outcome were entered in the model -LRB- see Table 1 -RRB- . As reported in Table 2 only three independent predictors were associated with severe RSV infection with hospitalization : a lower age category of the child , a lower birth weight category -LRB- < 1500 grams -RRB- , and birth order -LRB- being at least the second child in the family -RRB- . The number of children in the family and gestational age were not entered in the logistic model because of the strong autocorrelation , respectively , with the variables birth order and birth weight . Indeed , the vast majority of children -LRB- 84.6 % -RRB- belonging to the lowest gestational age category -LRB- < 33 weeks -RRB- and more than 60 % of those belonging to the intermediate gestational age category -LRB- 33 -- 35 weeks -RRB- had a birth weight < 2,500 grams . Table 2Best fitting logistic regression model for independent predictors of severe RSV infection with hospitalization -LRB- N = 419 -RRB- Explanatory variables aOR95 % CIP valueaChronological age at the beginning of RSV season -LRB- reference category : ≥ 12 months -RRB- 6 -- 11 months2 .4670.879 -- 6.925 P < 0.00013 -- 5 months4 .1531.506 -- 11.451 < 3 months8 .4623.088 -- 23.185 Birth weight category -LRB- reference category : ≥ 2,500 grams -RRB- 1,500 -- 2,499 grams2 .4331.289 -- 4.595 P = 0.0023 < 1,500 grams7 .7011.292 -- 45.907 Birth order -LRB- reference category : first -RRB- ≥ second1 .9241.210 -- 3.058 P = 0.0049 a Likelihood ratio testThe area under the ROC curve of the model was 0.712 Discussion Evaluating data collected over four consecutive years in Italy , we found that , in addition to the severity of the RSV epidemics in a specific year , a variety of risk factors were associated with a higher likelihood to acquire RSV-induced LRTI , severe enough to lead to hospital admission . The only condition related to demographic and social characteristics of the family was the number of children in the family -LRB- being at least the second baby was a `` risk-factor '' -RRB- . Among factors related to the characteristics of the children , major predictors were chronological age of the child at the onset of RSV season , birth weight and gestational age category , birth order , daycare attendance and previous episodes of RSV infections . However , in the logistic regression analysis , only three predictors turned out to be significant : chronological age at the beginning of RSV season , birth weight category , and birth order . These results only partially confirm previous observations regarding risk factors for severe RSV infection -LSB- 1 , 2 , 8 , 11 , 14 , 17 -RSB- . Chronological age of the child at the beginning of RSV season is a known factor for severe RSV-induced LRTI -LSB- 1 , 10 , 17 -- 19 -RSB- . Indeed , in our study population only six children -LRB- 4.1 % -RRB- with a chronological age at the beginning of the season > 12 months -LRB- and none between 2 to 4 years -RRB- had RSV-induced LRTI severe enough to lead to hospital admission . Aside from the incomplete development of the lung structure and the small size of the conducting airways related to the young age , data also suggest that such infants are less likely to have RSV-neutralizing maternal antibody as compared with infants born after the peak of the RSV season -LSB- 6 -RSB- . Birth weight was also an important risk factor in our study population . Low birth weight is often linked to low gestational age and there is no question that premature birth is , in general , associated with acute and chronic pulmonary morbidity -LSB- 3 , 5 , 7 -- 10 , 14 , 22 -RSB- . Prematurity , in RSV-induced LRTI , can lead to increased need for and lengthened duration of hospital admission , intensive care , mechanical ventilation and supplemental oxygen , as well as increased mortality -LSB- 1 , 21 -RSB- . Increased risk to develop severe RSV-induced LRTI may also be observed in the `` less premature '' infants , i.e. those with a gestational age of 32 weeks or greater , in the presence of other concomitant host/environmental unfavourable conditions , such as day-care attendance , low chronological age at the onset of RSV season , presence of preschool age sibling -LRB- s -RRB- , and low birth weight -LSB- 3 , 5 , 10 , 21 -RSB- . In the present study , gestational age , a strong risk factor in the bivariate analysis , was not included in the logistic model because of the strong autocorrelation with birth weight . Indeed , a great proportion of children belonging to two lower gestational age categories -LRB- < 33 weeks and 33 -- 35 weeks -RRB- had a birth weight < 2,500 grams . SGA has been only recently examined as an independent risk factor for hospitalization for RSV infection and , in agreement with the result of the present study , was found to be significant in a population of infants born at 33 through 35 weeks of gestation -LSB- 10 -RSB- . An interesting finding of the present report is that a low birth weight , corrected or uncorrected for gestational age , was a strong predictor for severe RSV-induced LRTI . The third important predictor in our study population was birth order , i.e. being at least the second child in the family was found to be a risk factor for severe RSV-induced LRTI . A variety of studies demonstrated a trend toward higher numbers of RSV hospitalization rates in infants with any older siblings , including preschool age siblings -LRB- younger than 6 years old -RRB- who attend daycare and school age siblings -LRB- older than 3 years -RRB- -LSB- 1 , 3 , 5 -- 7 , 10 , 18 , 19 , 21 -RSB- . In agreement with the majority of reports , other conditions related to demographic and social characteristics of the family -LRB- the number of children in the family -RRB- or of the environment -LRB- daycare attendance -RRB- were found in the bivariate analysis to be able to increase the likelihood to be hospitalized for RSV-induced LRTI -LSB- 1 , 3 , 5 -- 7 , 10 , 18 , 19 , 21 -RSB- . While the number of children in the family was not entered in the logistic model because of the strong autocorrelation with the variable birth order , daycare attendance did not reach a significant value in the logistic regression analysis , probably because of the small number of children attending daycare in our study population -LSB- 3 -LRB- 2.1 % -RRB- in the `` case '' group and 24 -LRB- 22.0 % -RRB- in the `` control '' group -RSB- . Despite other conditions , such as father 's and mother 's educational level , mother 's age category , social conditions , breast feeding , family history of allergy and gender and exposure to cigarette smoking , that were not statistically relevant in our study population , we can not exclude that other socio-economical and environmental factors might be important -LSB- 1 , 3 , 5 -- 7 , 10 , 18 , 19 , 21 -RSB- . As shown for other Mediterranean countries -LSB- 5 -RSB- , exposure to tobacco smoke at home has decreased during recent years in Italy as a result of anti-smoking campaigns and better health education , and this may explain our surprising results . Due to the low number of children with specific characteristics , other risk factors such as presence of chronic lung diseases or of congenital heart diseases , immunodeficiency , haematological malignancies , bone-marrow or organ transplants , and cystic fibrosis were not analysed . Moreover , since only in the second , third and fourth RSV season a limited number of children had received immunoprophylaxis with palivizumab , its protective effect could not be evaluated . In summary , evaluating four RSV seasons , characterized by inter-annual alternation of minor and major epidemics , we found , in addition to prematurity , a limited number of other conditions which appear to influence the severity of RSV-induced LTRI in infants and young children . However , before translating to clinical practice these indications , other similar studies performed in different countries are required , including a broader number of children and covering other RSV epidemic seasons . This information should be valuable to better determine hospital resource management and individualize RSV prophylaxis programs in preterm and term infants .

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 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O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 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O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O

respiratory syncytial virus infections
emergency rooms