Page 194 - 2019_01-Haematologica-web

C. Tromeur et al.
Table 4. Overview of studies on radiation exposure from CTPA or V-Q lung scanning in real-life patients. Radiation exposure: real-life studies
Study
Browne et al.2014 Jordan et al.20151
Moradi et al. 2015 Ridge et al.20112
Richard e et al.2015
Astani et al. 2014
Revel et al. 2011
Litmanovicth et al. 2009
Armstrong et al. 2017
Mitchell et al. 2017
Halpenny et al. 2017
Number of imaging tests
70 CTPA
34 CTPA
27 CTPA
28 CTPA
20 CTPA
77 V-Q lung scanning
23 V-Q lung scans 30 CTPA
94 V-Q lung scans 46 CTPA
26 CTPA
769 V-Q lung scans 269 CTPA
84 CTPA 120 kV 15 CTPA 80 kV
69A 135B
CTPA radiation exposure
V-Q lung scanning radiation exposure DLP
1st 2nd
9.0 9.5
mSv mSv
21.07 21.26
3rd Average
7.15 mSv*
9.7 9.4
mSv mSv
5.46 mSv*
4.8 mSv**
Q lung scanning
V-Q lung scanning
mGy/cm
397.54±100.4
NP
303.55±98.74
NP
NP NP
1st
2nd 3rd
Average
1st
2nd
3rd
Average
NP
NP
NP
NP
MMED mSv**** BAD mGy FAB mGy
Maternal
effective dose mSV**** BAD mGy UFAD mGy
MMED mSv
MMED
mSv BAD mGy
UFAD mGy
MED mSv
BAD mGy MMED mSv BAD mGy
Mean effective mSv
Mean
effective dose mSv
NP
0.27 1.24
5.6 mSV**
NP 2.18 5.82
0.19 0.24 0.19
1.04 1.00 1.07 0.28 0.27 0.29
0.24 0.27 0.24
0.21
1.04 0.28
0.25
NP 0.81 0.76 0.7 0.76 NP
43.36
0.47
43.14
0.51
20.74 21.02 46.55 44.35
0.38 0.46 7.3 mSv*
1.79 mSv
2-14
0.002-0.02
0.23 2.24 0.04 0.25
1.66 0.97
1.22 1.32 1.34 1.29 NP 0.35 0.37 0.39 0.37 NP
0.40 0.42 0.38 0.40 NP 0.9 mSv† NP
NP 105.65±39.77
0.28 NP
0.2 NP
NP NP NP NP NP
NP 118.48±20.05
NP 69.34±10.95
CTPA: computed tomography pulmonary angiography;V-Q lung scanning: ventilation-perfusion lung scanning; Q: perfusion; MMED: mean maternal effective dose; BA: breast absorbed dose; FAD: fetal absorbed dose; UFAD: uterus/fetal absorbed dose. NP: not provided. *DLP :dose length product (image noise) ; mSv =DLP mGy/cm *0.018(standard conversion). ** The mean effective dose per patient. †88MBq*11*10-3 ;eachinjectedmegabecquerelrepresentsaneffectivedoseof11*10-3 mSv.1AverageradiationexposureinmilliSieverts(k=18mSv/mGycm),Radiationdoseinpregnantpatients.2Two different CTPA protocols were assessed. **** dose calculation method not provided.
CTPA partly explains the recommendation of V-Q lung scans by international guidelines for pregnant patients with suspected PE. The Society of Thoracic Radiology clinical practice guidelines have presented comparable radiation exposure doses to our findings.74 However, since the studies in our review did not provide all imaging pro- tocol details or full disclosure of the mathematical formu- las used, the reported radiation doses in Table 5 are nei- ther comparable between studies nor reproducible. Moreover, mathematical body phantoms (Monte Carlo simulation) of pregnant patients were used instead of realistic physical phantoms in three of the CTPA phan- tom studies.65,66,68 The presented radiation exposure doses in both phantom and human studies should therefore be interpreted with great caution. Moreover, the risk of early breast cancer seems similar after VQ lung scanning and CTPA.75
State-of-the-art imaging techniques
For the diagnosis of acute PE, accuracy and pulmonary arterial opacification are significantly improved by opti- mizing the CTPA protocol for the pregnant patient. This optimization includes a high flow rate (6 instead of 4 mL/s), a high volume (an approximately 25% increase) fol- lowed by saline flush, a high concentration of contrast medium (370 mg I/mL), and shallow held inspiration (to avoid the Valsalva maneuver).24 In the Leiden University Medical Center, the contrast volume and speed are titrated according to the patient’s weight. Advised measures to reduce radiation dose include using a 100 kV protocol76 and reduced z-axis technique with limited scan volume from just above the aorta to the basal lung fields (excluding the upper and lower marginal zones).77 For the diagnosis of acute PE with lung scintigraphy in pregnancy, a two-step protocol is suggested to minimize radiation. Initially, per-
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