PMID- 33440020
OWN - NLM
STAT- MEDLINE
DCOM- 20210430
LR  - 20210430
IS  - 2473-4209 (Electronic)
IS  - 0094-2405 (Linking)
VI  - 48
IP  - 3
DP  - 2021 Mar
TI  - Effect of contrast agent administration on water equivalent diameter in CT.
PG  - 1117-1124
LID - 10.1002/mp.14721 [doi]
AB  - PURPOSE: Water equivalent diameter (WED) is the preferred surrogate for patient 
      size in computed tomography (CT). It is better than geometric size surrogates and 
      patient weight/height/BMI/age because it correlates the best with x-ray 
      attenuation. The administration of oral/IV contrast agents increases a patient's 
      attenuation and should therefore increase WED. Here we study the clinically 
      relevant effect of oral and IV contrast agent on WED. METHODS: We pulled 1703 
      routine adult abdominal/pelvis cases acquired at 100, 120, and 140 kV from our 
      PACS under retrospective IRB approval. One hundred and forty cases cases had no 
      oral or IV contrast (NONCON), 285 had just IV contrast (IV), 107 had just oral 
      contrast (ORAL), and 1171 had both oral and IV contrast (BOTH). For each case, we 
      measured the water equivalent and effective diameter (ED) from axial CT images. 
      We plotted the WED versus the ED for each class of contrast. We used a linear 
      regression model and omnibus F-test to determine if significant differences 
      between WED distributions existed between the contrast groups for each kV. We 
      then performed a post hoc analysis to determine if any significant differences 
      existed in pairwise comparisons of the different contrast groups. Bonferroni 
      correction was used to account for multiple comparisons. RESULTS: We found 
      statistically significant changes at 100 and 120 kV with a maximum change of 
      2.1 mm. We measured a ~25 mm spread (i.e., prediction interval) of WEDs within 
      all four contrast groups. CONCLUSIONS: While our sample size was large enough to 
      detect statistically significant differences between some of the contrast groups, 
      the differences were clinically irrelevant when one considers that the change in 
      size-specific dose estimate (SSDE) caused by our observations is roughly 1%.
CI  - (c) 2021 American Association of Physicists in Medicine.
FAU - Viggiano, Benjamin
AU  - Viggiano B
AD  - Department of Radiology, University of Wisconsin Madison, Madison, WI, USA.
FAU - Rose, Sean
AU  - Rose S
AD  - Department of Medical Physics, University of Wisconsin Madison, Madison, WI, USA.
FAU - Szczykutowicz, Timothy P
AU  - Szczykutowicz TP
AD  - Departments of Radiology, Medical Physics, and Biomedical Engineering, University 
      of Wisconsin Madison, 1111 Highland Avenue, Madison, WI, 1005 WIMR, USA.
LA  - eng
PT  - Journal Article
DEP - 20210211
PL  - United States
TA  - Med Phys
JT  - Medical physics
JID - 0425746
RN  - 0 (Contrast Media)
RN  - 059QF0KO0R (Water)
SB  - IM
MH  - Adult
MH  - *Contrast Media
MH  - Humans
MH  - Radiation Dosage
MH  - Retrospective Studies
MH  - *Tomography, X-Ray Computed
MH  - *Water
OTO - NOTNLM
OT  - AEC
OT  - SSDE
OT  - WED
EDAT- 2021/01/14 06:00
MHDA- 2021/05/01 06:00
CRDT- 2021/01/13 17:11
PHST- 2020/12/17 00:00 [revised]
PHST- 2020/08/03 00:00 [received]
PHST- 2021/01/06 00:00 [accepted]
PHST- 2021/01/14 06:00 [pubmed]
PHST- 2021/05/01 06:00 [medline]
PHST- 2021/01/13 17:11 [entrez]
AID - 10.1002/mp.14721 [doi]
PST - ppublish
SO  - Med Phys. 2021 Mar;48(3):1117-1124. doi: 10.1002/mp.14721. Epub 2021 Feb 11.