M. Stickel

Imaging of aortic abnormalities with contrast-enhanced ultrasound. A pictorial comparison with CT

Aortic abnormalities are commonly encountered and may represent a diagnostic challenge in patients with acute or chronic clinical symptoms. Contrast-enhanced ultrasound (CEUS) with low mechanical index (low MI) is a new promising method in the diagnosis and follow-up of pathological aortic lesions. CEUS with SonoVue allows a more rapid and noninvasive diagnosis, especially in critical patients because of its bedside availability. This review compares CEUS findings with those documented on computed tomography angiography (CTA), allowing the reader to appreciate the usefulness of CEUS in this clinical situation.

Contrast-enhanced ultrasound versus MS-CT in blunt abdominal trauma

To evaluate the effectiveness of contrast-enhanced ultrasound (CEUS) in the diagnosis and characterization of hepatic, renal and splenic traumatic injuries versus conventional ultrasound (US) and multislice computed tomography (MS-CT). Between January 2005 and January 2007, 78 patients (48 males, 30 females, mean age 56 years) with blunt abdominal trauma were examined by conventional US, CEUS and MS-CT. CEUS employed a low-MI technique using 1.2 to 2.4 ml of SonoVue (Bracco, Italy) i.v. and a multifrequency transducer (2-4 MHz, Siemens, Sequoia, Acuson). CT examinations were performed on a 64 detector CT scanner (Somatom Sensation 16 or 64, Siemens Medical Systems, Forchheim, Germany) before and after administration of 120 ml intravenous contrast agent (Solutrast, Bracco, Milan, Italy) followed by 50 ml saline. The presence of hepatic, renal and splenic injuries was analyzed and the conspicuousness of findings was assessed. In 15 of the 78 patients conventional US identified solid organ injuries: 8 hepatic, 2 renal and 5 splenic injuries. CEUS identified 3 more injuries (2 hepatic and 1 splenic) that had been missed by conventional US. CEUS identified traumatic lesions in 18/78 patients. In one of the 18 patients even active bleeding could be identified by CEUS. In CEUS solid organ injuries appeared hypoechoic. MS-CT identified 18 solid organ injuries in 78 patients, corroborating the CEUS results.CEUS greatly improves the visualization and characterization of hepatic, renal and splenic injuries compared to conventional ultrasound and correlates well with MS-CT. The imaging technique detects even minor blood flow and is able to depict vascular structures in detail. At our institution it is used as an additional examination technique which supplements MS-CT in unclear cases. Owing to its bedside availability, CEUS provides a good alternative to MS-CT, especially in patients with contraindications to CT contrast agents (e.g. due to renal failure or severe allergy) and in hemodynamically compromised patients.

Contrast-Enhanced Ultrasound in Detection and Follow-Up of an Infrarenal Abdominal Aortic Aneurysm with Aorto-Caval Fistula and Endovascular Treatment

An aorto-caval fistula is a rare complication of a symptomatic or ruptured infrarenal aortic aneurysm having a frequency of 3–6%. Patients typically present with clinical signs of diffuse abdominal pain associated with increasing venous congestion and tachycardia, rapid cardiopulmonary decompensation with acute dyspnea, and an audible machinerylike bruit. Perioperative mortality is high, ranging from 20% to 60%. We report a case of an endovascular aortic repair in a patient with a symptomatic infrarenal aortic aneurysm and an aorto-caval fistula. Contrast-enhanced ultrasound seems to be a promising new diagnostic option for the diagnosis and preoperative treatment planning for patients with abdominal aortic aneurysms with rupture into the inferior vena cava. It is in addition to computed tomography angiography. It might allow a more rapid and noninvasive diagnosis, especially for patients in intensive care because of its bedside availability. Because the examination is dynamic, additional information about blood flow between the aorta and inferior cava vein can be evaluated.

Contrast-enhanced ultrasound in liver transplant: First results and potential for complications in the postoperative period

PURPOSE This study compared the efficacy of contrast-enhanced ultrasound (CEUS) using a second generation contrast medium versus CT or MRA in the assessment of vascular and biliary complications in postoperative follow-up of liver transplantation. METHODS AND MATERIALS The study group consisted of 36 consecutive liver transplant recipients who underwent post-transplantation CEUS examination after developing ascites and/or unclear liver function tests. Real time CEUS was performed after a bolus injection of SonoVue (1.6-2.4 ml, Bracco, Imaging Germany) followed by 10 ml of saline solution. Using contrast harmonic imaging (CHI) technique (Logiq 9, GE) with a 2.5-4-MHz transducer, a low mechanical index was chosen to avoid early destruction of the microbubbles (MI 0.1-0.2). In order to confirm the results, the patients underwent contrast-enhanced MRI or CT. RESULTS Complications were identified in 16 of 36 patients (44.4%). Five transplants (14%) had hepatic artery thrombosis (n=2) or significant stenosis (n=3). Six transplants (16%) developed portal vein stenosis (n=4) or portal vein thrombosis (n=2). MRI or CT confirmed the findings of the CEUS in all 11 cases. Biliary stricture at the anastomotic site was detected in 5 patients. MR-CP confirmed the findings of all strictures. CONCLUSION Due to advances in contrast-enhanced US, vascular and biliary complications in the postoperative period following liver transplantation can be reliably diagnosed non-invasively on the intensive care unit. CEUS shows vascular as well as biliary complications in the postoperative patient with a high degree of accuracy.

Imaging of endoleaks after endovascular aneurysm repair (EVAR) with contrast-enhanced ultrasound (CEUS). A pictorial comparison with CTA

Endoleaks following endovascular aneurysm repair (EVAR) are common and present a diagnostic challenge in the follow-up after EVAR. Contrast-enhanced ultrasound (CEUS) with low mechanical index (low MI) is a promising new method for the diagnosis and follow-up of endoleaks. CEUS with SonoVue allows a more rapid and noninvasive diagnosis, especially in critical patients owing to its bedside availability. This review describes the etiology, classification and importance of different types of endoleaks and compares CEUS findings with computed tomography angiography (CTA), allowing the reader to appreciate the usefulness of CEUS in this clinical situation.

Value of ultrasound in the diagnosis of aneurysms of the extracranial internal carotid arteries

Aneurysms of the extracranial carotid arteries are a rare abnormalitiy and may represent a diagnostic challenge in examination of the patients. B-flow is a new digital vascular ultrasound technique and is an especially reliable method in the diagnosis of the extracranial portion of the internal carotid arteries as it shows less flow artifacts than color-coded Doppler sonography (CCDS) and power Doppler (PD). This review compares color-coded Doppler sonography, power Doppler and B-flow findings in extracranial ICA and CA aneurysm to emphasize the usefulness of B-flow in this clinical condition.

Contrast-enhanced ultrasound versus CT and operative findings in evaluation of renal vein aneurysm with AV fistula

We report the case of a 61-year-old patient admitted to our hospital owing to recent nonspecific abdominal pain. Five years earlier he had been treated with a graft owing to thoracic and abdominal aortic aneurysm with dissection. He now showed a left renal vein aneurysm with a diameter of 11x7.5 cm. This case demonstrates that contrast enhanced ultrasound (CEUS), employed in addition to computed tomography angiography, offers a promising new option for diagnosis and preoperative treatment planning in patients with abdominal vascular diseases. The results were compared with operative findings.

Value of vascular ultrasound in the evaluation of hemodialysis fistulas

ZusammenfassungDer vaskuläre Ultraschall ist eine etablierte Technik in der Shuntdiagnostik und ermöglicht eine nichtinvasive Diagnostik der Gefäßmorphologie und Hämodynamik. Möglichst frühzeitig sollen stenosierende Gefäßwandveränderungen eines Dialyseshunts erkannt werden, um einen thrombotischen Verschluss zu vermeiden. Das sichere Erkennen auch echoarmer Wandveränderungen und die Beurteilung des lokalen Stenosegrades erleichtern eine Interventionsentscheidung. Hierbei rechtfertigen hohe Verschlussraten bei vermindertem Durchflussvolumen von bis zu 45% innerhalb eines Jahres eine sonographische Verlaufsuntersuchung. Das Risiko hämodynamisch relevanter Shuntstenosen wird durch häufige Punktionen im Rahmen perkutaner Interventionen gesteigert. Durch die Einführung neuer Ultraschallverfahren wie B-Flow und Advanced Dynamic Flow (ADF) kann eine direkte Darstellung des Flusses im Anastomosenbereich erleichtert werden. Darüber hinaus eröffnen sich durch eine hochauflösende Ultraschalldiagnostik neue Möglichkeiten einer verbesserten Flussdetektion ohne Gefäßüberzeichung oder Aliasing. In der vorliegenden Arbeit wird auch auf Untersuchungsstrategien, mögliche Komplikationen und deren Behandlungsmöglichkeit durch die perkutane Interventionstechnik eingegangen.AbstractVascular ultrasound has been proven to be effective in the assessment of hemodialysis fistulas providing noninvasive diagnostic work-up of vascular morphology and hemodynamics. The most common reason for hemodialysis fistula failure is thrombosis due to stenosis. Therefore, early identification of stenosis is essential to avoid complications. Ultrasound-based identification of hypoechoic plaques and intimal proliferation helps to reach therapeutic decisions. An estimation of the grade of stenosis is also feasible. An occlusion rate of up to 45% due to reduced blood flow justifies follow-up examinations. Due to frequent puncture of the fistula the risk of hemodynamically relevant stenoses is increased. Establishment of new ultrasound methods like B-flow and advanced dynamic flow (ADF) enable direct visualization of the flow in the area of the anastomosis. In addition, high-resolution ultrasound techniques allow improved flow detection without aliasing. Our report addresses the topics of examination strategy, possible complications, and treatment like percutaneous intervention techniques.

Formen und Komplikationen des Hämodialyseshunts – Stellenwert der Sonographie

ZusammenfassungDer vaskuläre Ultraschall ist eine etablierte Technik in der Shuntdiagnostik und ermöglicht eine nichtinvasive Diagnostik der Gefäßmorphologie und Hämodynamik. Möglichst frühzeitig sollen stenosierende Gefäßwandveränderungen eines Dialyseshunts erkannt werden, um einen thrombotischen Verschluss zu vermeiden. Das sichere Erkennen auch echoarmer Wandveränderungen und die Beurteilung des lokalen Stenosegrades erleichtern eine Interventionsentscheidung. Hierbei rechtfertigen hohe Verschlussraten bei vermindertem Durchflussvolumen von bis zu 45% innerhalb eines Jahres eine sonographische Verlaufsuntersuchung. Das Risiko hämodynamisch relevanter Shuntstenosen wird durch häufige Punktionen im Rahmen perkutaner Interventionen gesteigert. Durch die Einführung neuer Ultraschallverfahren wie B-Flow und Advanced Dynamic Flow (ADF) kann eine direkte Darstellung des Flusses im Anastomosenbereich erleichtert werden. Darüber hinaus eröffnen sich durch eine hochauflösende Ultraschalldiagnostik neue Möglichkeiten einer verbesserten Flussdetektion ohne Gefäßüberzeichung oder Aliasing. In der vorliegenden Arbeit wird auch auf Untersuchungsstrategien, mögliche Komplikationen und deren Behandlungsmöglichkeit durch die perkutane Interventionstechnik eingegangen.AbstractVascular ultrasound has been proven to be effective in the assessment of hemodialysis fistulas providing noninvasive diagnostic work-up of vascular morphology and hemodynamics. The most common reason for hemodialysis fistula failure is thrombosis due to stenosis. Therefore, early identification of stenosis is essential to avoid complications. Ultrasound-based identification of hypoechoic plaques and intimal proliferation helps to reach therapeutic decisions. An estimation of the grade of stenosis is also feasible. An occlusion rate of up to 45% due to reduced blood flow justifies follow-up examinations. Due to frequent puncture of the fistula the risk of hemodynamically relevant stenoses is increased. Establishment of new ultrasound methods like B-flow and advanced dynamic flow (ADF) enable direct visualization of the flow in the area of the anastomosis. In addition, high-resolution ultrasound techniques allow improved flow detection without aliasing. Our report addresses the topics of examination strategy, possible complications, and treatment like percutaneous intervention techniques.

Treatment of Secondary Stent-Graft Collapse After Endovascular Stent-Grafting for Iliac Artery Pseudoaneurysms

We report the case of a patient who developed an asymptomatic pseudoaneurysm in the left external iliac artery after transplant nephrectomy. The pseudoaneurysm most probably arose as a suture aneurysm from the external iliac artery after removal of the graft renal artery. Obviously we can not exclude the possibility it was a true aneurysm, although this seems much less likely. The pseudoaneurysm was detected during a routine CT scan and was treated interventionally with a stent-graft. One month later the asymptomatic patient underwent a vascular ultrasound examination including color Doppler, power Doppler, and B-flow as a routine control. An endoleak with collapse of the stent-graft was diagnosed. There was no evidence of stent infection. At a reintervention, the pseudoaneurysm was successfully treated using two uncovered Palmaz stents at the proximal and distal edge of the stent graft. Peri- and post-interventional ultrasound and CT angiography confirmed the exclusion of the aneurysm without an endoleak.