Roberto Iezzi

Contrast-enhanced ultrasound versus color duplex ultrasound imaging in the follow-up of patients after endovascular abdominal aortic aneurysm repair

PURPOSE This study assessed the negative predictive value, sensitivity, specificity, and diagnostic accuracy of real-time contrast-enhanced ultrasound imaging (CEUS) in the detection of endoleaks in patients with abdominal aortic aneurysm (AAA) who underwent endovascular repair (EVAR) compared with unenhanced ultrasound imaging. Computed tomography angiography (CTA) was the gold standard. The secondary objective was to define the optimal dose of the second-generation contrast agent to routinely use in the CEUS examinations for endoleak detection. METHODS The study enrolled 84 patients with unruptured AAA who were treated with EVAR and underwent CTA follow-up. In the same day, CTA (4- x 1-mm collimation, 1.25-mm slice width), unenhanced US imaging and CEUS imaging was performed in all patients. The CEUS studies were performed after an intravenous bolus injection of 1.2 mL and 2.4 mL of a second-generation contrast agent with continuous low-mechanical index (range, 0.01-0.04) real-time tissue harmonic imaging. The unenhanced US and CEUS studies were interpreted separately by two independent experienced readers to detect the presence of endoleaks by viewing recorded videotapes according to a five-point confidence scale. The standard of reference was represented by the consensus reading of CTA performed by two experienced radiologists not involved in the image analysis. Qualitative analysis as well as sensitivity, specificity, negative predictive value, and diagnostic accuracy in detecting endoleaks of each reading session were compared. RESULTS CEUS imaging significantly improved the diagnostic performance of unenhanced US studies in the detection of endoleaks in terms of sensitivity (97.5% vs 62.5%), negative predictive value (97.3% vs 65.1%), accuracy (89.3% vs 63.1%), and specificity (81.8% vs 63.6%). The optimal dose of contrast agent to detect and characterize endoleaks was 2.4 mL. No adverse events were recorded during the study. CONCLUSIONS The results showed CEUS imaging is a fast, noninvasive, reliable, and valid alternative to multislice CTA for endoleak detection in endovascular aortic stent graft patients, and is superior to unenhanced US imaging. Contrast-enhanced ultrasound imaging should be performed using a recommended contrast medium dose of 2.4 mL.

Multidetector-row CT angiographic imaging of the celiac trunk: anatomy and normal variants.

PurposeTo evaluate the ability of MDCT reformations in describing the celiac trunk vascular anatomy and variations.Materials and methodsA total of 555 MDCT angiographies of the abdominal aorta performed between January 2002 and July 2005 were retrospectively reviewed to assess the celiac trunk vascular anatomy and variations. All the patients with pathological condition likely to affect normal vascular anatomy as well as CT exams technically inadequate were excluded from our study.ResultsA total of 524 MDCT angiographies of abdominal aorta were included in our study. The classical configuration of the celiac trunk was detected in 72.1%. The hepato-splenic trunk was detected in 50.4% of cases; the hepato-gastro-splenic trunk was detected in 19.4% of cases; the gastro-splenic trunk was detected in 2.3% of cases. The hepato-spleno-gastric trunk associated with hepatic arteries variants were found in 15.4%. The hepato-splenic trunk, the hepato-gastric trunk, the hepato-splenic-mesenteric trunk, and the spleno-gastric trunk were found in 2.7, 5, 0.4, and 3.6%, respectively. In 0.6%, we found an absent celiac trunk.ConclusionThe knowledge of the type of anatomical variants and their subtypes is fundamental for a correct pre-operative vascular planning in surgical or radiological abdominal procedures. Multidetector-row CT (MDCT) provides high-quality 3D-reconstructed images and allows non-invasive assessment of normal anatomy and anatomic variants of celiac trunk.

Bridging and downstaging treatments for hepatocellular carcinoma in patients on the waiting list for liver transplantation

Several therapeutic procedures have been proposed as bridging treatments for patients with hepatocellular carcinoma (HCC) awaiting liver transplantation (LT). The most used treatments include transarterial chemoembolization and radiofrequency ablation. Surgical resection has also been successfully used as a bridging procedure, and LT should be considered a rescue treatment in patients with previous HCC resection who experience tumor recurrence or post-treatment severe decompensation of liver function. The aims of bridging treatments include decreasing the waiting list dropout rate before transplantation, reducing HCC recurrence after transplantation, and improving post-transplant overall survival. To date, no data from prospective randomized studies are available; however, for HCC patients listed for LT within the Milan criteria, prolonging the waiting time over 6-12 mo is a risk factor for tumor spread. Bridging treatments are useful in containing tumor progression and decreasing dropout. Furthermore, the response to pre-LT treatments may represent a surrogate marker of tumor biological aggressiveness and could therefore be evaluated to prioritize HCC candidates for LT. Lastly, although a definitive conclusion can not be reached, the experiences reported to date suggest a positive impact of these treatments on both tumor recurrence and post-transplant patient survival. Advanced HCC may be downstaged to achieve and maintain the current conventional criteria for inclusion in the waiting list for LT. Recent studies have demonstrated that successfully downstaged patients can achieve a 5-year survival rate comparable to that of patients meeting the conventional criteria without requiring downstaging.

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.

Endovascular abdominal aortic aneurysm repair: how many patients are eligible for endovascular repair?

Purpose.The purpose of this study was to determine how many patients with abdominal aortic aneurysm (AAA) are eligible for endovascular abdominal aortic aneurysm repair (EVAR).Materials and methods.We retrospectively reviewed computed tomography (CT) angiograms obtained between January 2002 and June 2003 in 182 patients with suspected AAA. Indication for surgical or endovascular treatment was based on clinical and radiological criteria. The percentage of patients eligible for EVAR was evaluated.Results.Out of a total of 182 patients with suspected AAA studied by CT angiography, after combined radiological–surgical assessment, 130 were considered eligible for surgical or endovascular treatment (71.4%). EVAR was indicated in 51 patients (39.3%, group A) and surgical repair was indicated in 79 patients (60.7%, group B). The reasons for ineligibility for EVAR were the following: unfavourable anatomy of the proximal neck in 41 patients (51.9%), diameter of the aneurysm sac >7 cm in 13 patients (16.4%), markedly tortuous/dilated iliac axis in six patients (7.6%), age <65 years in 17 patients (21.5%) and patient refusal in two cases (2.5%). There were no statistically significant differences in aneurysm diameter (52.7±0.8 versus 49.8±1.2 mm, p=ns), patients’ age (73.2±1.2 versus 70.6±2.02 years, p=ns) or proximal neck length (2.95±1 versus 3.03±1.2 cm, p=ns) between groups A and B.Conclusions.Endovascular repair of abdominal aortic aneurysms through the placement of aortic stent–grafts has now become a viable alternative to open surgery. In recent years, the number of patients treated with EVAR has steadily risen as a result of increased physician experience, availability of new and more versatile devices and improvements in noninvasive imaging techniques. Unfavourable neck anatomy is the primary factor for exclusion from endovascular repair.

Diagnostic Performance of Gadobenate Dimeglumine–Enhanced MR Angiography of the Iliofemoral and Calf Arteries: A Large-Scale Multicenter Trial

OBJECTIVE The purpose of this study was to compare gadobenate dimeglumine-enhanced MR angiography and unenhanced time-of-flight MR angiography for the detection of significant peripheral arterial occlusive disease using digital subtraction angiography as our reference standard. SUBJECTS AND METHODS Two hundred seventy-two patients underwent MR angiography and digital subtraction angiography of the iliofemoral arteries. MR angiography was performed before (2D time-of-flight acquisitions) and after (spoiled gradient-echo acquisitions) the administration of 0.1 mmol/kg of gadobenate dimeglumine at 1-2 mL/s. Contrast-enhanced MR angiography and digital subtraction angiography of the calf arteries were performed in 241 of 272 participants. Images were evaluated on-site and by four blinded reviewers (three for MR angiography, one for digital subtraction angiography). Comparative diagnostic performance for the detection of significant (> or = 51% vessel lumen narrowing) disease was evaluated using the McNemar test and generalized estimating equations. Interobserver agreement was assessed with generalized kappa statistics. The chi-square test was used to compare technical failure rates. RESULTS Digital subtraction angiography confirmed significant disease (597 stenoses, 386 occlusions) in 983 iliofemoral segments. The sensitivity (54-80.9%), specificity (89.7-95.3%), and accuracy (85-87.5%) of contrast-enhanced MR angiography for the detection of significant iliofemoral disease were significantly (p < 0.001, all reviewers) better than those of time-of-flight MR angiography (33.2-62.8%, 74.3-88.9%, and 68-77.3%, respectively). Similar diagnostic performance was obtained for the calf arteries. The technical failure rate with contrast-enhanced MR angiography (2.5-3.4%) was similar to that of digital subtraction angiography (1.4%) and significantly (p < 0.001) lower than that of time-of-flight MR angiography (6.2-18.0%). Significantly better reproducibility (p < 0.001) was obtained with contrast-enhanced MR angiography (82% vs 65.2% agreement; kappa = 0.66 vs 0.45). CONCLUSION Improved diagnostic performance and reproducibility are achievable with gadobenate dimeglumine-enhanced MR angiography in patients with peripheral arterial occlusive disease.

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 × 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.

Low-dose multidetector-row CT-angiography of abdominal aortic aneurysm after endovascular repair

PURPOSE To investigate the possibility of reducing radiation dose exposure while maintaining image quality using multidetector computed tomography angiography (MDCTA) with high-concentration contrast media in patients undergoing follow-up after endovascular aortic repair (EVAR) to treat abdominal aortic aneurysm. MATERIALS AND METHODS In this prospective, single center, intra-individual study, patients underwent two consecutive MDCTA scans 6 months apart, one with a standard acquisition protocol (130 mAs/120 kV) and 120 mL of iomeprol 300, and one using a low dose protocol (100 mAs/80 kV) and 90 mL of iomeprol 400. Images acquired during the arterial phase of contrast enhancement were evaluated both qualitatively and quantitatively for image noise and intraluminal contrast enhancement. RESULTS Thirty adult patients were prospectively enrolled. Statistically significantly higher attenuation values were measured in the low-dose acquisition protocol compared to the standard protocol, from the suprarenal abdominal aorta to the common femoral artery (p<0.0001; all vascular segments). Qualitatively, image quality was judged significantly (p=0.0002) better with the standard protocol than with the low-dose protocol. However, no significant differences were found between the two protocols in terms of contrast-to-noise ratio (CNR) (13.63±6.97 vs. 11.48±8.13; p=0.1058). An overall dose reduction of up to 74% was observed for the low-dose protocol compared with the standard protocol. CONCLUSION In repeat follow-up examinations of patients undergoing EVAR for abdominal aortic aneurysm, a low-dose radiation exposure acquisition protocol provides substantially reduced radiation exposure while maintaining a constant CNR and good image quality.

EVAR: Benefits of CEUS for monitoring stent-graft status

Endo vascular aortic repair [EVAR] is performed with low peri-operative morbidity and mortality rate and short hospital stay. However, EVAR needs a close and lifelong imagining surveillance for a timely detection of possible complications including endoleaks, graft migration, fractures, and enlargement of aneurysm sac size with eventual rupture. Contrast enhanced computed tomography [CTA] is actually considered the gold-standard in EVAR follow-up, but it is accompanied with radiation burden and renal injury due to the use of contrast media. In the last two decades several studies have shown the role of contrast enhanced ultrasound [CEUS] in post-EVAR surveillance, with very good diagnostic performance, absence of renal impairment, and no radiation, accompanied by low costs, in comparison with CTA. In numerous prospective studies and meta-analyses the detection and characterization of endoleaks with CEUS is comparable to that of CTA imaging. Nowadays, in the EVAR surveillance novel strategies which involve CEUS with a central role, are suggested by several authors and applied in many institutions. In this review article we will present a comprehensive overview and analyses of the literature on the CEUS state-of-art imagining of EVAR follow-up, with its technique, findings, diagnostic accuracy, and its role in the follow up program.

Endoleaks after endovascular repair of abdominal aortic aneurysm: value of CEUS

Endovascular repair (EVAR) is playing an increasingly role in the treatment of abdominal aortic aneurysm. A successful procedure depends on the complete sealing of the aneurysm sac from blood flow to achieve general pressure relief and avoid aneurysm rupture, with a shrinkage of the aneurysm sac. The most common complication of EVAR is endoleak that is the persistence of perigraft flow within the aneurysm sac, which has to be considered the major cause of enlargement and rupture of the aneurysm, and the main indication for surgical late conversion. For this reason, strict surveillance of these patients is mandatory for the early detection of endoleaks and the preferred method of follow-up is represented by CT angiography. However, CTA has limitations. The investigation is repeated several times, making radiation exposure a necessary concern. Therefore, it would be useful to have another reliable diagnostic examination during follow-up. Color duplex ultrasound is non-invasive, does not use radiation or contrast medium, is less expensive, easy to perform and widely available. However, this technique obtained poor results in terms of sensitivity in the detection of endoleaks. In the last years, the introduction of ultrasound contrast agents and contrast-specific imaging has, however, rekindled interest in this modality and its potential for replacing of CTA in routine surveillance. The purpose of this review is to highlight the diagnostic value of CEUS in the post-EVAR endoleaks detection.