Volumetric quantification of type II endoleaks: an indicator for aneurysm sac growth following endovascular abdominal aortic aneurysm repair.
OBJECTIVE
To test the hypothesis that type II endoleak cavity volume (ECV) and endoleak cavity diameter (ECD) measurements are accurate indicators of aneurysm sac volume (ASV) enlargement in patients who undergo endovascular aneurysm repair (EVAR) in the abdominal aorta.


METHODS
The institutional review board approved and waived the need to obtain patient consent for this HIPAA-compliant retrospective study. In 72 patients who underwent EVAR, 160 computed tomographic (CT) angiography studies revealed type II endoleaks. Corresponding to these 160 CT angiography studies, 113 CT follow-up studies (in 52 patients) were available and were included in the analysis. ECV measurements were obtained by two observers in consensus by using arterial enhanced phase (ECVAEP) and 70-second delayed enhanced phase (ECVDEP) CT images. The ECVDEP was also normalized as the ECV/ASV ratio. Maximum (ECDM) and transverse (ECDT) ECDs were determined from delayed enhanced phase images. The outcome was determined as interval increase (>2%) in ASV versus stable or decreasing (≤2%) ASV. Receiver operating characteristic (ROC) analysis was used to compare the accuracy of type II ECV and ECD measurements in indicating interval increase in ASV.


RESULTS
In 56 (49.5%) of 113 CT studies in type II endoleaks, there was an interval increase in ASV. The accuracies of ECVDEP (area under the ROC curve [AUC], 0.85) and normalized ECVDEP (AUC, 0.86) were superior to the accuracies of ECDM (AUC, 0.73), ECDT (AUC, 0.73), and ECVAEP (AUC, 0.66). At ROC curve analysis, the sensitivity, specificity, and positive and negative predictive values for type II endoleak cavities with an ECVDEP of less than 0.5 mL for showing no future sac volume enlargement were 33% (19 of 57), 100% (56 of 56), 100% (19 of 19), and 60% (56 of 94), respectively.


CONCLUSIONS
With use of the delayed enhanced phase of CT angiography, ECV measurement is an accurate indicator of aneurysm sac enlargement.
From the Department of Radiology (J.S., K.K.K., N.W., E.G., M.L.S., F.J.R.), Applied Imaging Science Laboratory (S.D., J.S., K.K.K., N.W., E.G., M.L.S., F.J.R.), and Department of Vascular Surgery (E.C.G.), Brigham and Women's Hospital, Boston, Mass.
Shadpour
S
Demehri
Jason
J
Signorelli
Kanako K
KK
Kumamaru
Nicole
N
Wake
Elizabeth
E
George
Michael
M
Hanley
Michael L
ML
Steigner
Michael L
ML
Steinger
Edwin Charles
EC
Gravereaux
Frank J
FJ
Rybicki
D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D019917:Blood Vessel Prosthesis Implantation; D057867:Endoleak / Q000145:classification / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome