Interventional radiological treatment of renal transplant complications: a pictorial review.

Renal transplantation is the treatment of choice for patients with chronic renal failure, which produces a dramatic improvement in the quality of life and survival rates, in comparison to long-term dialysis. Nowadays, new imaging modalities allow early diagnosis of complications, and thanks to the recent developments of interventional techniques, surgery may be avoided in most cases. Knowledge in the types of renal transplant complications is fundamental for a correct pre-operative planning. In this article, we described the most common or clinically relevant renal transplant complications and explained their interventional management.

Diagnostic accuracy of CT angiography in the evaluation of stenosis in lower limbs: comparison between visual score and quantitative analysis using a semiautomated 3D software.

OBJECTIVE: To assess the accuracy of a semiautomated 3-dimensional (3D) computed tomographic angiography software in the evaluation of lower limb stenoses compared to reader evaluation, using digital subtraction angiography (DSA) as standard of reference. MATERIALS AND METHODS: Forty patients with peripheral vascular occlusive disease underwent both DSA and computed tomographic angiography. The vascular tree was divided into 6 segments from distal aorta to popliteal artery. Each district was evaluated for significant stenosis by one experienced vascular radiologist (on axial as well as 3D images) and by a semiautomated 3D software analysis, independently. Evaluation of the vessel evaluation was then repeated by a poorly experienced radiologist twice, first without 3D software analysis and then supported by 3D software analysis. RESULTS: Both experienced radiologist and automated evaluations obtained high statistical results when compared to DSA. The analysis by poorly experienced radiologist obtained lower statistical results, which significantly improved when supported by 3D software analysis. CONCLUSIONS: Three-dimensional analysis software should be feasible to identify significant vascular stenoses and may help a poorly experienced radiologist to significantly improve diagnostic accuracy.

Low-dose multidetector CT angiography in the evaluation of infrarenal aorta and peripheral arterial occlusive disease.

PURPOSE: To investigate the ionizing radiation dose, image quality, and diagnostic performance of computed tomographic (CT) angiography of the peripheral arteries with three different CT angiographic acquisition protocols, with use of pretreatment digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: The study was approved by the institutional review board and performed in agreement with the 1990 Declaration of Helsinki and subsequent amendments. Each patient provided informed consent before undergoing CT. The authors performed a prospective, single-center, randomized comparison of three different x-ray exposure CT acquisition protocols in 60 randomized patients with peripheral arterial occlusive disease referred for 64-section multidetector CT angiography of the lower limb (0.625-mm collimation, intravenous administration of 100 mL of iomeprol [400 mg iodine per milliliter] at 4 mL/sec). The acquisition protocols were performed with (a) 120 kVp and a noise index of 26 (moderate noise reduction [MNR]), referred to as the 120-kVp MNR group; (b) 80 kVp and a noise index of 26, referred to as the 80-kVp MNR group; and (c) 80 kVp and a noise index of 30 (high noise reduction [HNR]), referred to as the 80-kVp HNR group. Axial and three-dimensional (3D) images were qualitatively and quantitatively compared by using the overall F test and pairwise comparisons. The X(2) test was used to compare the three protocols in terms of diagnostic performance in patients who also underwent DSA before an interventional procedure. RESULTS: Significantly higher attenuation values were obtained in the vessels with the 80-kVp MNR and 80-kVp HNR acquisition protocols. No significant differences were noted in terms of image quality with either axial source images or 3D reconstructions. Likewise, no significant differences were found among the three protocols in terms of noise throughout the peripheral vasculature. Finally, no significant differences were found among the three groups with regard to diagnostic performance. Overall dose reductions of 48% and 61% were obtained for the 80-kVp MNR and 80-kVp HNR protocols, respectively. CONCLUSION: Substantial reductions of radiation dose are achievable at multidetector CT angiography of the peripheral arteries without compromising image quality and diagnostic performance if acquisition protocols are modified appropriately and used in conjunction with a contrast material containing a high concentration of iodine.

Proximal aneurysmal neck: dynamic ECG-gated CT angiography--conformational pulsatile changes with possible consequences for endograft sizing.

PURPOSE: To assess the magnitude of variations in size of the proximal neck of the abdominal aortic aneurysm (AAA) in patients selected to undergo endovascular abdominal aortic aneurysm repair (EVAR) and the potential effect on choice of endograft diameter by using 64-section dynamic electrocardiographically (ECG)-gated computed tomographic (CT) angiography. MATERIALS AND METHODS: A prospective single-center study was performed in 40 patients with AAA who underwent both static and dynamic ECG-gated CT angiography. The ethical conduct of the study was approved by the departmental review board, and all patients provided written informed consent. Dynamic ECG-gated data sets were acquired with a low-dose acquisition protocol (100 kV) by using a 0.625-mm-section collimation (40 mL iomeprol [400 mg of iodine per milliliter] versus 80 mL). Pulsatility measurements were taken at suprarenal, juxtarenal, and infrarenal levels within the aneurysmal neck. Manual CT angiographic measurements were performed on modified axial images. On static axial images, one vascular surgeon and one interventional radiologist selected the diameter of the main body of the potential infrarenal stent-graft to implant. The diameter of the main body of the stent-graft selected was compared with the dynamic measurements obtained to calculate the potential relative oversizing performed. RESULTS: A total of 40 patients were enrolled. Significant aortic pulsatility was demonstrated within the aneurysmal neck (mean variation, 9.01% ± 4.81 [standard deviation]; absolute change, 1.83 mm ± 1.01; P < .05). When compared with dynamic measurements, the diameter of the endograft selected on the basis of static images would be potentially changed in 12 of 40 (30%) patients. Comparing the minimum or maximum diameter of the aneurysmal neck with the diameter of the endograft selected on the basis of static images, the relative oversizing performed was considered inadequate in seven of 40 (18%) patients. CONCLUSION: Dynamic ECG-gated CT may provide information in regard to pulsatile motion that could change the diameter of the endograft selected on the basis of static imaging measurements.

CT angiography in stent-graft sizing: impact of using inner vs. outer wall measurements of aortic neck diameters.

PURPOSE: To assess the impact of using inner wall vs. outer wall measurements on stent-graft sizing for endovascular repair of abdominal aortic aneurysm (AAA). METHODS: Preoperative static and electrocardiographically-gated 64-slice computed tomographic angiography (CTA) datasets were acquired on 40 consecutive AAA patients (29 men; mean age 78.9 ± 6 years, range 75-89). On static images, the aortic neck diameters were manually measured twice by 2 readers at 3 clinically relevant levels (supra-, juxta-, and infrarenal). The measurements were obtained from intima-to-intima (inner wall) and from adventitia-to-adventitia (outer wall). Dynamically reconstructed scans were also reviewed in each phase of the cardiac cycle to identify inner and outer minimum/maximum diameters. Using inner and outer wall measurements performed on static images, readers selected the size of a stent-graft that required inner neck diameter measurements and then one that required outer wall diameters. To calculate the relative oversizing, each selected stent-graft size was compared to that obtained using dynamic measurements. Oversizing <4% or >30% was considered inadequate. RESULTS: Mean variations for the inner and outer wall diameters of 9.75% ± 4.01% and 8.66% ± 3.71%, respectively, were recorded on static CTAs; the absolute changes in diameters were 1.82 ± 0.63 mm and 1.91 ± 0.64 mm, respectively. No statistically significant differences were found relative to aortic pulsatility at the 3 levels in the neck for the inner or outer wall diameters. Significant variability was seen between inner (mean 20.8 ± 3.4 mm) vs. outer (mean 23.7 ± 4.3 mm; p < 0.05) wall diameters. Stent-graft sizes significantly changed on the basis of the measurement method and device; for example, using the outer diameter to size a stent-graft that requires an inner diameter reference changed 36% of the selected stent-graft sizes, with ~20% being excessively oversized. Conversely, using the inner diameter to size an outer-diameter-based stent-graft resulted in nearly 40% of the sizes being altered. Based on dynamic measurements, the changes were more dramatic: the oversizing was considered excessive in up to 90% of patients if the measurement method did not match the stent-graft's stipulated reference. CONCLUSIONS: These data suggest that stent-graft sizing should follow the manufacturer's recommendations for using inner or outer diameter references based on dynamic patterns (mean value between diastolic and systolic diameters suggested).