Aortic dissection: CT features that distinguish true lumen from false lumen.

OBJECTIVE: The purpose of this study was to determine which CT findings are reliable indicators of the true or false lumen in an aortic dissection. CONCLUSION: The beak sign and a larger cross-sectional area were the most useful indicators of the false lumen for both acute and chronic dissections. Features generally indicative of the true lumen included outer wall calcification and eccentric flap calcification. In cases showing one lumen wrapping around the other lumen in the aortic arch, the inner lumen was invariably the true lumen.     

Intimomedial rupture: a new CT finding to distinguish true from false lumen in aortic dissection

OBJECTIVE: The purpose of our study is to describe a new imaging finding observed on contrast-enhanced MDCT of discontinuity in the intimomedial flap seen with aortic dissection that may identify the level of intimomedial entrance tear and distinguish true from false lumen. CONCLUSION: Direct visualization of an intimomedial rupture on MDCT is a valuable cross-sectional imaging sign indicating direction of the intimomedial entrance tear from true to false lumen in cases of aortic dissection. The presence of this finding enables reliable distinction of the true lumen, where the tear is broad-based and erupts into the false lumen, which receives the evaginating tear. Improved scanning techniques through MDCT may have enabled recognition of this relatively infrequent, yet highly specific, finding.     

Simultaneous presentation of both true and false aneurysm in the infrarenal aorta

Interventional radiology has resulted in a reduced need for bypass procedures for aorto-occlusive disease. However, there are still indications for surgery of this type, which carries with it a small but significant morbidity and mortality. False aneurysms are well described following such procedures but with the development of inert, strong and non-absorbable materials they are becoming less common. This paper describes the acute presentation of a false aneurysm of the aorta following an aorto-iliac bypass where true aneurysmal change had taken place in the area of the anastomosis.     

Thrombosis of the false lumen in acute aortic dissection. CT diagnosis

Three cases are reported of acute aortic dissection with complete thrombosis of the false channel, which is a very uncommon event in De Bakey's I and II type aortic dissections. The 3 patients entered hospital because of severe thoracic pain without any ECG sign of myocardial infarction. Emergency CT showed evidence of pericardial effusion suggesting hemopericardium, enlargement of the ascending aorta and a peripheral semilunar filling defect which caused a slight deformation of the true channel. On precontrast scans, only one case showed inward displacement of peripheral intimal calcifications and high-density aortic wall. No typical signs of aortic dissection were reported, except in the first patient--where a double contrast filled lumen, separated by an intimal flap was seen. CT findings are individually discussed. It is emphasized that in all patients more than one CT sign was present at a time. The correct evaluation of these signs together with the clinical data could lead to the right diagnosis of aortic dissection in spite of the lack of a filled false channel.     

Differentiation between dissection and a true aneurysm of the descending thoracic aorta using magnetic resonance tomography

The case reviewed here demonstrates that magnetic resonance imaging in contrast to CT and i.v. DSA can differentiate between aortic dissection with partially thrombosed false lumen and a true aneurysm using the spin-echo and the gradient-echo technique. The gradient-echo technique was able to depict the moving intimal flap as well as the higher blood flow velocity in the true lumen.     

Differentiation of benign from malignant superficial lymphadenopathy: the role of high-resolution US.

Ultrasonography has proved a valuable tool for the detection of enlarged lymph nodes; however, differentiation between benign and malignant nodal disease remains a problem. High-frequency probes with improved spatial and contrast resolution display superficial nodes to advantage and also show the internal structure of the nodes. Ninety-four superficial nodes in patients with suspected nodal disease were examined by using 7.5-MHz probes to evaluate longitudinal-transverse diameter ratio (L/T), the central hilus, cortical widening, and size. Histologic diagnosis was obtained after sonographic examination in 73 nodes (five reactive nodes, 35 primary nodal malignancies, and 33 nodal metastases). The remaining 21 nodes regressed after either antibiotic or no therapy. Marked differences were observed among the proportions of benign and malignant nodes in terms of L/T, hilus, and cortex; the latter two structures, however, must be interpreted together. Eccentric cortical widening was seen in only malignant nodes. The distribution of nodal size was not significantly (P greater than .1) different for benign and malignant nodes. No differences were observed between primary and secondary nodal malignancies. The sonographic criteria evaluated in this study assist in the differentiation of benign from malignant superficial lymph nodes.     

Fate of the false lumen following surgical repair of aortic dissections: an angiographic study.

Postoperative angiography was performed in 27 patients who had surgical repair for aortic dissections. The ascending aorta was involved in 22 dissections (Type A), while in five dissections it was uninvolved (Type B). Findings were assessed between two weeks and 13 years postoperatively. Despite the primary surgical objective to abolish flow in the false lumen, the majority of patients, whether symptomatic or not, continued to harbor patent distal false channels. In certain cases, one or more vital aortic branches were perfused solely by the false lumen. Initial postoperative angiography is indicated for determined surgical results as well as the functional significance of late angiographic findings, should symptoms recur. Further extension of the initial dissection, redissection, or enlargement of localized saccular aneurysms may mandate late reoperation. These conditions manifest themselves by pain, aortic regurgitation, neurological sequelae, or compromise of blood flow to a vital organ or extremity.     

Embolization of a prosthetic mitral valve leaflet: localization with intravascular US.

The authors describe a case in which a leaflet from a mitral valve prosthesis embolized to the right external iliac artery. Intravascular ultrasound proved useful in locating the valve fragment prior to and during surgery, allowing for its removal.     

Evaluation of the inferior vena cava with intravascular US after Greenfield filter placement.

An animal model was used to evaluate the utility of intravascular ultrasound (US) imaging of the inferior vena cava (IVC) following Greenfield filter placement. Ten Greenfield filters were placed in the IVCs of five sheep and three dogs. Experimentally induced thrombi were injected into four filters at the time of placement. Intravascular US and cavography were performed 4 weeks after filter implant. The imaging studies were evaluated for demonstration of filter position, orientation, and leg distribution, as well as prediction of caval wall penetration by filter hooks. Experimentally induced and spontaneous intrafilter thrombi were also imaged. Findings were compared with those of postmortem examination. Exact filter position and orientation were most simply and accurately demonstrated on radiographs. Filter leg distribution and extent of intrafilter thrombus were best evaluated on intravascular US images. The prevalence of caval wall penetration was underestimated with both studies. The results of this animal study suggest that the information about the IVC provided at cavography and intravascular US following Greenfield filter placement may be complementary.     

冠状动脉CTA自动三维定量非钙化性斑块:与血管内超声的对比研究

目的评价先前研发的自动算法[AUTOPLAQ(APQ)]对冠状动脉CT血管成像中非钙化性斑块和钙化性斑块的快速容积定量的准确性,并与血管内超声进行对照。     

Virtual CT intravascular endoscopy of the aorta: pierced surface and floating shape thresholding artifacts.

Two types of artifacts may appear in virtual computed tomographic endoscopic views of the aorta rendered at different threshold levels: pierced surface and floating shape artifacts. A positive correlation was found between mean attenuation of the aorta and the threshold levels at which these artifacts appeared. The correlation was statistically significant (0.71 < or = r < or = 0.86) for floating shape. An artifact-free threshold range can be predicted on the basis of aortic enhancement.     

Chronic aortic dissection: Stenting of aortic true lumen obliteration with late dynamic variations of both lumens

Percutaneous endovascular techniques were used to treat an arteriovenous fistula (AVF) associated with pancreatic transplantation. A pancreatic transplant superior mesenteric artery-to-superior mesenteric-vein AVF was successfully embolized while flow to the pancreas transplant was preserved. The embolization was aided by the use of Guglielmi detachable coils and a detachable balloon. No complications were encountered. At 23 months follow-up, the patient is doing well with no recurrence.     

Human coronary and peripheral arteries: on-line three-dimensional reconstruction from two-dimensional intravascular US scans. Work in progress.

To explore the feasibility of computer-based, on-line three-dimensional reconstruction, timed manual withdrawal (pullback) recordings were obtained with two-dimensional intravascular ultrasound (US) in 42 patients who underwent percutaneous revascularization. Three-dimensional processing was performed with commercial software that stacked serially obtained intravascular US scans and created a new set of data points in four steps: interpolation, segmentation, boundary encoding, and surface rendering. In all 42 patients, satisfactory on-line three-dimensional reconstruction was accomplished. In the first three patients, 70-90 seconds was required for three-dimensional processing, and display was limited to the sagittal format. In the next six patients, a sagittal display was rendered in 45-60 seconds, and on-line reconstruction in the cylindrical format was achieved within 30 additional seconds. In the last 33 patients, an unlimited number of sagittal views could be produced in 30-40 seconds, the extra time required for cylindrical display was shortened to 15-20 seconds, and a luminal cast display was added to the on-line menu.     

Opacification of the aorta in arteritis of the legs. Dilemma or false problem?

Recent advances in therapy: angioluminal dilatation, fibrinolysis, microsurgery, require precise arterial visualization, to include the aorta, to prevent lack of recognition of an embolus of aortic origin. The new techniques for vascular visualization have modified the algorithm of exploration of an arteritis of lower limbs. Ultrasound and CT scan imaging are effective but do not exclude the use of angiography before deciding therapy. Digital subtraction venous angiography is insufficiently precise for aortic exploration but is a good method for diagnosis of peripheral artery lesions. Digital subtraction arterial angiography is perhaps the method for the future but it requires multiple injections. A place still exists for traditional aortoarteriography for exploration of lower limb arteritis, at least for patients under 65 years of age and in good general condition.