Wolf 2000.

Clinical features and settings	People who received endovascular repair of AAA with bifurcated endograft. Type of stent received: AneuRx (Medtronic). Aneurysm diameter: not reported. Setting: vascular surgery department, Stanford University Hospital.
Participants	100 consecutive participants (age and gender not reported). Comorbidities: not reported. Geography: USA.
Study design	Prospective cross‐sectional study (consecutively selected participants, all received both tests).
Target condition and reference standard(s)	Target condition: endoleak. Definition of endoleak: no definition reported. Endoleak (absolute n): unclear. Prevalence of endoleak: 38.0% (62/163). Reference standard: CTA. Image acquisition: "single detector‐row CT scans were acquired at a pitch 2.0 with a 3.0 mm nominal section thickness from the celiac origin to the infrarenal aorta, followed by a 5.0 mm nominal section thickness to the femoral bifurcation. Multi detector‐row CT scans were acquired at pitch 6.0 with a 2.5 mm nominal section thickness throughout the entire scan. All images were reconstructed at intervals equal to 50% of nominal section thickness and viewed interactively on a workstation. Biphasic enhanced CT was performed on using the same protocol and imager (HiSpeed Advantage, IGE Medical Systems, Slough, UK)." Type of CT scanner: CT scanner (both General Electric Medical Systems, Milwaukee, WI, USA). Use of contrast: yes (type not reported).
Index and comparator tests	Index test: CDUS. Image production: "The protocol included transverse and sagittal imaging and peak systolic diameter measurements at the largest region of the proximal, mid, and distal segments of the abdominal aorta. Visible segments of the iliac arteries were also measured. Close attention was given to the stent device in gray scale and in colour Doppler scanning to rule out endoleak and graft compression." Type of US: Sequoia 512 ultrasound scanning system (Acuson, Mountain View, CA, USA) and sector V4 transducer. Use of contrast: no. Operator: 1 ("the vascular technologist was not aware of the CT scan").
Follow‐up	No apparent loss to follow‐up, missing data, or adverse events.
Notes	"Standardized duplex scanning protocol was used for assessing the abdominal aorta. The protocol included transverse and sagittal imaging and peak systolic diameter measurements at the largest region of the proximal, mid, and distal segments of the abdominal aorta. Visible segments of the iliac arteries were also measured. Close attention was given to the stent device in gray scale and in colour Doppler scanning to rule out endoleak and graft compression. All duplex ultrasound scans were reviewed by a vascular surgeon." "Follow‐up protocol included CT angiography before discharge, duplex scan at 1 month, and CT angiography at 6 months, 1 year, and yearly thereafter. To compare CT and duplex scans, we obtained both studies, whenever possible, within a period of 7 days from each other." "A total of 268 postoperative CT scans (2.7 ± 1.7 scans per patient) and 214 postoperative duplex scans (2.1 ± 1.9 scans per patient) were obtained over 1 to 30 months of follow‐up (mean interval, 9 ± 7 months)."
Table of Methodological Quality
Item	Authors' judgement	Description
Representative spectrum? All tests	Yes	Enrolled participants who "underwent endovascular repair for AAA with the AneuRx (Medtronic) bifurcated endograft at Stanford University Hospital from October 1996 to May 1999. Follow‐up protocol included CT angiography before discharge, duplex scan at 1 month, and CT angiography at 6 months, 1 year, and yearly thereafter."
Acceptable reference standard? All tests	Yes	Reference standard was CT scan.
Acceptable delay between tests? All tests	Unclear	Delay between 2 tests in 24 participants unclear. "To compare CT and duplex scans, we obtained both studies, whenever possible, within a period of 7 days from each other. CT and duplex scans were obtained concurrently (within 7 days of each other) in 166 instances in 76 patients (1‐6 scan pairs per patient). These concurrent scan pairs form the basis for the comparison between the tests."
Partial verification avoided? All tests	Yes	All study participants accounted for and results of reference standard reported for all.
Differential verification avoided? All tests	Yes	All participants who received index test subjected to same reference standard.
Incorporation avoided? All tests	Yes	Index test not part of reference standard.
Reference standard results blinded? All tests	Yes	"During the examination and the reading of the duplex scan, the vascular technologist was not aware of the CT scan results."
Index test results blinded? All tests	Yes	"In addition to a formal reading by a radiologist who was unaware of the duplex scan result, CT angiograms were reviewed by a panel of radiologists and vascular surgeons to confirm the presence or absence of an endoleak."
Relevant clinical information? All tests	Yes	Yes.
Uninterpretable results reported? All tests	Yes	"All CT scans were technically satisfactory. Delayed scans, which were obtained routinely after September 1998, were performed in 57% of CT scans. Sixteen (7%) duplex scans in 10 patients were technically inadequate for determination of aneurysm size and presence of endoleak."
Withdrawals explained? All tests	Unclear	Unclear.