Diagnostic sensitivity of multidetector-row spiral computed tomography angiography in the evaluation of type-II endoleaks and their source: comparison between axial scans and reformatting techniques.
BACKGROUND
After endovascular stent-graft placement, several complications may occur. Retrograde filling of the aneurysm (type-II endoleak) is the most common.


OBJECTIVE
To evaluate the accuracy, image quality, and interobserver agreement of multidetector-row spiral computed tomography angiography (MDCTA) in the diagnosis of type-II endoleak, by using various types of reformatting techniques in comparison to regular axial images.


METHODS
Twenty-four patients who had had endovascular repair of an infrarenal abdominal aortic aneurysm with stent graft were retrospectively studied. In 12 of 24 patients, a type-II endoleak was found. CT scans were obtained after intravenous administration of 130 ml of nonionic contrast material using a 4-6-ml/s flow rate. All patients were investigated with axial scans, multiplanar reconstruction (MPR), maximum intensity projection (MIP), shaded-surface display (SSD), and volume-rendering (VR) techniques. For each patient and for each reconstruction method, the image quality of the scans was scored as 0 for bad quality, 1 for poor quality, 2 for good quality, and 3 for excellent quality images. Two radiologists reviewed the CT images independently. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each reconstruction method, with the axial images as the reference method. Interobserver agreement and kappa value were also recorded.


RESULTS
MPR showed the highest sensitivity (83% and 67% for observers 1 and 2, respectively), PPV (91% and 80% for observers 1 and 2, respectively), and NPV (85% and 71% for observers 1 and 2, respectively), whereas VR showed the highest specificity (92% for both observer 1 and 2).


CONCLUSIONS
Reformatting techniques provide good-quality images; nevertheless, their efficacy in the study of type-II endoleak was found to be suboptimal in comparison to regular axial images. The MPR technique is probably the best choice in conjunction with axial images.
Saba
L
L
Department of Radiology, Azienda Ospedaliero-Universitaria di Cagliari, Polo di Monserrato, Monserrato, Cagliari, Italy.
Pascalis
L
L
Montisci
R
R
Sanfilippo
R
R
Mallarini
G
G
D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000295:instrumentation* / Q000379:methods; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging; D017544:Aortic Aneurysm, Abdominal / Q000601:surgery; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011183:Postoperative Complications / Q000175:diagnosis; D011856:Radiographic Image Enhancement / Q000379:methods; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D015607:Stents / Q000009:adverse effects*; D036542:Tomography, Spiral Computed / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome
D003287:Contrast Media; D007472:Iohexol; C038192:iopromide