Delayed Helical CT Acquisition in the Detection of Endoleak [letter]

Experience With Fenestrated Endovascular Repair of Juxtarenal Abdominal Aortic Aneurysms at a Single Center

To present the early and mid-term results of fenestrated endovascular aneurysm repair (FEVAR) using the Zenith fenestrated device for juxtarenal abdominal aortic aneurysms (JAAAs) at our center in China.

DESIGN

Retrospective study.The study included 15 male patients with JAAAs, who underwent FEVAR using the Zenith fenestrated device at our center between February 2011 and June 2015.All custom-made Zenith fenestrated devices were designed according to computed tomography angiography (CTA) images obtained preoperatively. The patients with renal insufficiency underwent duplex ultrasonography, while the patients with normal renal function underwent 3 CT data acquisitions including nonenhanced CT, arterial phase, and venous phase. These examinations and blood examinations were completed at 3, 6, and 12 months after discharge, and annually thereafter.The mean age of the patients was 73.13 ± 9.06 years (range, 57-86 years), and the median follow-up period was 30 months (8-52 months). Small fenestrations were used in 27 renal arteries, scallops were used in 7 superior mesenteric arteries (SMAs) and 2 renal arteries, and large fenestrations were used in 2 SMAs. Conversion to an open procedure was not required in any of the patients, and the technical success rate was 100%. The mean length of hospital stay was 11.33 ± 2.02 days (7-15 days). No patient died within the 1st 30 days after the operation. One patient had a type Ia endoleak, which disappeared at 6 months after the operation, 1 patient had a type Ib endoleak, which was detected at 17 months after the operation, and 2 patients had type II endoleaks. One patient died at 17 months and another patient died at 30 months after the operation. Therefore, the all-cause mortality rate was 13.33% (2/15). The target vessel patency rate was 100% without occlusion.The early and mid-term results of FEVAR using the Zenith fenestrated device were good, demonstrating that this procedure is effective for the treatment of JAAAs.

Multidetector-row computed tomography angiography in abdominal aortic aneurysm treated with endovascular repair: evaluation of optimal timing of delayed phase imaging for the detection of low-flow endoleaks

PURPOSE

To evaluate the optimal timing of delayed phase imaging for detecting low-flow endoleaks.

MATERIALS AND METHODS

Fifty-eight patients with unruptured abdominal aortic aneurysm treated with endovascular repair underwent 1- and 6-month follow-up multidetector row computed tomography (CT) performed during unenhanced, arterial, and delayed phase. At 6-month follow-up, delayed phase imaging, focused on stent graft, was performed with a delay of 60 (early delayed enhanced phase) and 300 seconds (late delayed enhanced phase) after intravenous injection of 120 mL of iodinated nonionic contrast medium (iomeprol 300 mgI/mL, Iomeron), at a flow rate of 3 mL/s via an antecubital vein, with a detector-row configuration of 4 x 1-mm, a 1.25-mm slice width, and a pitch of 6. Six-month follow-up CT images were independently evaluated by 2 readers during 2 different reading sessions: sets A (unenhanced, arterial, and early delayed phase images) and B (unenhanced, arterial, and late delayed phase images). Sensitivity and diagnostic accuracy of both reading sessions were compared. The standard of reference was represented by the combined evaluation of 1- and 6-month CT scans.

RESULTS

At standard of reference, 24 of 58 patients had an endoleak classified as type 1 in 2 cases, type 2 in 21 cases, and type 3 in the last 1 case. Seven of 21 type 2 endoleaks were classified as low-flow endoleaks. Set A reading session, including early delayed enhanced phase, allowed the detection of 19 of 24 endoleaks (5 false-negative cases represented by low-flow endoleaks), whereas all endoleaks were detected during set B reading session, including late delayed enhanced phase. Differences between sets A and B in terms of sensitivity and diagnostic accuracy were statistically significant (P < 0.05).

CONCLUSIONS

For optimal multidetector CT detection of low-flow endoleaks in patients who underwent endovascular repair, delayed phase should be acquired 300 seconds after injection of contrast medium.

Multidetector CT in Abdominal Aortic Aneurysm Treated with Endovascular Repair: Are Unenhanced and Delayed Phase Enhanced Images Effective for Endoleak Detection?

PURPOSE

To retrospectively determine the sensitivity and specificity of unenhanced, delayed enhanced phase (DEP), and arterial enhanced phase (AEP) multi-detector row computed tomography (CT) for depicting endoleaks during follow-up of endovascular aneurysm repair.

MATERIALS AND METHODS

Fifty patients (two women, 48 men; mean age, 72 years) underwent follow-up multi-detector row CT 1, 6, and 12 months after endovascular aneurysm repair. Unenhanced CT was performed with 2.5-mm collimation; 1-mm collimation was used with AEP and DEP examinations. Two independent readers assessed the presence of endoleak in three reading sessions: AEP (session A), unenhanced and AEP (session B), and AEP and DEP (session C). At 6- and 12-month follow-up, a fourth set was included: 1-month unenhanced and AEP (session D). Sensitivity, specificity, and positive predictive value of each session were calculated. Triple-phase multi-detector row CT was the reference standard.

RESULTS

At 1 month, sensitivity, specificity, and positive predictive value, respectively, were 79%, 75%, and 55% for session A; 93%, 97%, and 93% for session B; and 93%, 78%, and 62% for session C. At 6 months, sensitivity, specificity, and positive predictive value, respectively, were 92%, 68%, and 48% for session A; 92%, 100%, and 100% for session B; and 100%, 84%, and 67% for session C. At 12 months, sensitivity, specificity, and positive predictive value, respectively, were 80%, 80%, and 50% for session A; 90%, 98%, and 90% for session B; and 100%, 80%, and 56% for session C. Sensitivity did not significantly differ (P > .05) among reading sessions A, B, and C, whereas specificity and positive predictive values in session B were significantly higher (P < .001). For 6- and 12-month follow-up, no significant differences (P > .05) were found between sessions D and B.

CONCLUSION

The combination of AEP and unenhanced imaging performed at 1-month follow-up offers improved specificity and positive predictive values compared with AEP alone. DEP imaging does not significantly increase sensitivity for detection of endoleaks, but it does depict low-flow endoleaks not seen at AEP.