Antonio Raffaele Cotroneo

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.

Delayed MR imaging of hepatocellular carcinoma enhanced by Gadobenate Dimeglumine (Gd-BOPTA).

The purpose of this study was to determine the efficacy of gadobenate dimeglumine (Gd‐BOPTA)‐enhanced magnetic resonance (MR) imaging for evaluation of hepatocellular carcinoma HCC. MR images were obtained in 14 patients with 31 HCC nodules as a part of a phase III clinical trial. T1‐ and T2‐weighted images were obtained before and after iv administration of 0.1 mmol/kg of Gd‐BOPTA. Two blinded readers evaluated pre‐ and delayed postcontrast images separately for detection of tumor nodules. Quantitative measurements of signal‐to‐noise (SNR) and tumor/liver contrast‐to‐noise (CNR) ratios were also performed. A signal/intensity ratio was calculated. Tumor enhancement was correlated with histologic findings. Consensus agreement of precontrast T1‐ and T2‐weighted images revealed 23/31 HCC nodules in 14 patients; postcontrast T1‐weighted images demonstrated 24/31 HCC nodules in the same number of patients. Combining both pre‐ and postcontrast images, 27/31 lesions were detected. Four patients had four well‐differentiated HCC nodules detected only on postcontrast images, while three well‐differentiated lesions in two patients were only seen on precontrast images. Quantitative evaluation showed an SNR ratio increase in both liver parenchyma and HCC nodules, as well as a significant increase in the absolute CNR ratio on postcontrast T1‐weighted gradient‐recalled images (P < 0.05). Well‐differentiated HCC lesions showed a greater enhancement than poorly differentiated HCC lesions. J. Magn. Reson. Imaging 1999;9:704–710.

Color Doppler sonography in the diagnosis and monitoring of arterial complications after liver transplantation

We assessed the usefulness of color Doppler imaging in the diagnosis and monitoring of arterial complications after liver transplantation.

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.

Diffusion-weighted magnetic resonance for prediction of response after neoadjuvant chemoradiation therapy for locally advanced rectal cancer: preliminary results of a monoinstitutional prospective study.

PURPOSE To evaluate diffusion-weighted imaging (DWI) for assessment of treatment response in locally advanced rectal cancer (LARC) 8 weeks after neoadjuvant chemoradiotherapy (CRT). METHODS AND MATERIALS A total of 28 patients with LARC underwent magnetic resonance imaging (MRI) prior to and 8 weeks after CRT. Tumor volume (TV) was calculated on T2-weighted MRI scans as well as the apparent diffusion coefficient (ADC) was calculated using Echo-planar DWI-sequences. All data were correlated to surgical results and histopathologic tumor regression grade (TRG), according to Mandards classification. Post-treatment difference ADC (%ΔADC) and TV (%ΔTV) changes at 8 weeks were compared complete response (CR; TRG1) and non-complete response tumors (non-CR; TRG2-5). RESULTS The mean % ADC increase of CR group was significantly higher compared to non-CR group (77.2 ± 54.63% vs. 36.0 ± 29.44%; p = 0.05). Conversely, the mean % TV reduction did not significantly differ in CR group from non-CR group (73.7% vs. 63.77%; p = 0.21). Accordingly, the diagnostic accuracy of the mean % ADC increase to discriminate CR from non-CR group was significantly higher than that of the mean % TV reduction (0.913 vs. 0.658; p = 0.022). No correlation was found between mean % TV reduction and TRG (rho = 0.22; p = 0.3037), whereas a negative correlation between mean % ADC increase and TRG was recorded (r = -0.69; p = 0.006). CONCLUSION The mean % ADC increase appears to be a reliable tool to differentiate CR from non-CR after CRT in patients with LARC.

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.

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.

Obscure and occult gastrointestinal bleeding: comparison of different imaging modalities.

Patients with persistent, recurrent, or intermittent bleeding from the gastrointestinal (GI) tract for which no definite cause has been identified by initial esophagogastroduodenoscopy, colonoscopy, or conventional radiologic evaluation are considered to have an obscure GI bleeding (OGIB). The diagnosis and management of patients with OGIB is challenging, often requiring extensive and expensive workups. The main objective is the identification of the etiology and site of bleeding, which should be as rapidly accomplished as possible, in order to establish the most appropriate therapy. The introduction of capsule endoscopy and double balloon enteroscopy and the recent improvements in CT and MRI techniques have revolutionized the approach to patients with OGIB, allowing the visualization of the entire GI tract, particularly the small bowel, until now considered as the “dark continent” . In this article we review and compare the radiologic and endoscopic examinations currently used in occult and OGIB, focusing on diagnostic patterns, pitfalls, strengths, weaknesses, and value in patients’ management.

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.