a.
Patient data
This retrospective multi-center study was approved by our institutional review board.
One hundred sixty-seven patients with ICD or LVAD implantation underwent to neuroemergency CT examinations (head CT,
head and neck CT angiography) between January 2014 and October 2018 were included in this study.
Patients were classified into two groups towards the type of implanted cardiac devices as LVAD and ICD groups.
LVAD group included 75 patients (120 male,
55 female,
mean age: 54±11) and ICD group included 92 patients (46 male,
46 female,
mean age: 67±12).
b.
CT technique and dose analysis
The study data was obtained from three different medical centers using a preformatted data form.
The contents of the preformatted data form included demographic characteristics of patients (age,
sex,
type of cardiac device,
diagnosis on (imaging findings) CT,
number of repetitive CT scans and the CT acquisition parameters including scanning type (sequence or spiral scanning),
kV,
tube rotation time (TI),
slice collimation (cSL) and CT dose products including computed tomography dose index volume (CTDIvol,
total dose length product (DLP).
The participating blinded radiologists obtained the parameters relevant to radiation dose from the scan protocol generated by the seven different CT (2 GE Medical Systems
,
4 Siemens,
1 Toshiba) systems from the three centers after each cranial CT and head and neck CT angiography.
The cumulative radiation dose of patients with ICD and LVAD were compared and the variability of CT acquisition parameters were interrogated.
c.
Statistical analysis
Results are expressed as counts (or proportions in %) or as minimum,
median and maximum values (interquartile range [IQR]).
Continuous and categorical variables were analyzed with a Wilcoxon rank sum and Mann-Whitney U test.
P values less than 0.001 were considered statistically significant.
d.
Results
A total of 1206 CT examinations (1152 head CT,
54 head and neck CTA) were performed in 168 patients.
Mean number of CT examination per patient was 8.
The mean number of cranial CT scans in ICD and LVAD group was 2 (min:1,
max:15) and 13 (min:1,
max:37),
respectively. 64 patients (%38.9) received one,
42 patients (%25.1) received 2-5,
11 patients (%6.5) received 5-10 and 48 patients (%28.7) received more > 10 cranial CT scans between 2014 and 2018.
The minimum,
mean and maximum overall DLP (mGy) and CTDIvol in ICD and LVAD groups are given in Table 1.
There was a significant difference in cumulative radiation exposure between LVAD and ICD group (p<0.001).
CT acquisition parameters that influence radiation dose varied between the centers and the CT equipments in the same center.
Table 1: The overall DLP and CTDIvol in a patient with LVAD and ICD.
|
Type of device
|
Minimum overall DLP (mGy-cm)
|
Mean overall DLP (mGy-cm)
|
Maximum overall DLP (mGy)
|
Minimum CTDIvol
|
Mean CTDIvol
|
Maximum CTDIvol
|
|
LVAD
|
4831
|
6847
|
20207
|
12.65
|
44.75
|
184
|
|
ICD
|
284
|
1129
|
9628
|
10.25
|
44.15
|
62.01
|
Table 2: Variability of CT acquisition parameters used in different vendors of three different centers are summarized.
|
CT acquisition parameters
|
Subgroups
|
|
|
|
Scanning type
|
Spiral
|
Sequence
|
|
|
|
kV
|
110
31 (N)
|
120
503 (N)
|
130
450 (N)
|
|
|
TI (s)
|
0,5
109 (N)
|
1
102 (N)
|
1,5
249 (N)
|
|
|
Slice collimation (mm)
|
0,6
52(N)
|
1
23 (N)
|
1,2
47 (N)
|
5
399 (N)
|
Cranial CT examinations revealed unremarkable findings in 51 (30.50%) patients,
acute ischemia in 13 (7.78%) patients,
chronic ischemia in 62 (37.12%) patients,
acute hemorrhage in 37 (22.15%) patients,
prominent arterial stenosis in 2 (1.19%) patients and non-neurological event in 2 (1.19%) patients.
Out of 85 patients presenting with an initial diagnosis of acute cerebrovascular accident,
the final diagnosis was chronic ischemia in 43 (50.58%) patients,
acute ischemia in 10 (11.76%) patients,
parenchymal hematoma in 32 (37.64%) patients and normal findings in 10 (11.76%) patients.
