CT angiography of lower extremity vascular bypass grafts

Over the past several years computed tomography (CT) technology has advanced to such a degree that CT angiography (CTA) has become the study of choice at our institution for imaging lower extremity vascular bypass grafts. CTA quickly provides anatomic information about the state of the graft and identifies virtually all forms of bypass graft failure and related complications. Furthermore, detailed vascular anatomy is seen beyond the graft and affords sufficient anatomic detail for surgical revision without the need for other angiographic studies. Although catheter angiography, duplex-ultrasound, magnetic resonance angiography, and nuclear medicine studies all continue to play some role in the evaluation of vascular grafts, they are more often used as problem solving modalities when CTA findings are equivocal. Whereas it was once essential to catheterize directly through a failing bypass graft or pass catheters into the graft from a distant arterial puncture to obtain an angiogram of a failing bypass graft, CTA produces arteriograms with only intravenous contrast administration, a brief visit to the CT scanner, and return to daily activities without catheterization, discomfort, or risk to the bypass conduit.     

Techniques for color flow sonography of the lower extremity

Color flow sonography permits noninvasive examination of the deep venous system in the lower extremity. In many patients, the modality is sufficiently accurate to serve as the sole diagnostic procedure for suspected deep venous thrombosis. Over 1,500 color flow sonographic examinations of the lower extremity have been performed at our institutions with various scanning techniques. For the inexperienced sonographer, we describe our current technique, which is easy, quick, accurate, and well tolerated by patients.     

Abdominal Takayasu's arteritis: imaging with color duplex sonography

Takayasu's arteritis is a inflammatory process of unknown etiology affecting mainly the thoracic and abdominal aorta and producing steno-occlusive findings of various degrees in different sites. We present a case of Takayasu's disease in a young woman, studied by color duplex sonography and verified by angiography. Received 22 April 1996; Revision received 4 September 1996; Accepted 15 July 1997     

Common hepatic artery aneurysm: diagnosis with duplex sonography and color Doppler.

Hepatic artery aneurysms are uncommon lesions, often with a nonspecific clinical presentation and difficult to diagnose before rupture. The authors report a case which was correctly diagnosed with non-invasive procedures (duplex sonography and color Doppler).     

Percutaneous vascular access guided by color duplex sonography

Color duplex sonography (CDS) is primarily applied as a diagnostic procedure. It has not yet established itself as an aid in punctures or other interventions. The aim of this study was to evaluate the value of CDS in arterial and venous vascular punctures. One hundred and sixty-five CDS-assisted vascular punctures were performed in a prospective study after three unsuccessful palpation-guided vasopunctures or in the absence of a palpable pulse. All CDS-assisted punctures were successful. The duration of each attempted puncture showed no statistically significant difference compared with the palpation-guided puncture technique. In the cases with three unsuccessful palpation-guided vascular punctures, the CDS-assisted technique was successful after 1.66 attempts on the average. It is concluded that CDS-assisted vascular puncture is a fast and safe alternative for puncturing a pulseless vessel or for puncturing under difficult conditions. Received 4 September 1996; Revision received 20 December 1996; Accepted 3 February 1997     

Underassessment of lower extremity deep venous thrombosis using color flow Doppler compared to compression sonography

The aim of this paper is to compare the accuracy of color Doppler to compression sonography in the diagnosis of lower extremity deep vein thrombosis. Longitudinal color flow imaging was performed in 60 lower extremities in patients with clinically suspected deep venous thrombosis (DVT). The study was then repeated by a blinded examiner using transverse compression sonography. The results were then correlated. Thirty-five examinations were negative by both color flow and compression methods. Twenty thrombi were diagnosed on compression sonography, while only 13 were diagnosed by the color flow method. Thirty-five percent of thrombi were missed using color flow imaging alone. We conclude that compression sonography should remain an integral part of the assessment of lower extremity DVT, as a significant number of thrombi might be overlooked using longitudinal color flow imaging alone. This is especially true in non-occlusive thrombi that are adherent to the vessel wall.     

Thrombosis of upper extremity thoracic inlet veins: diagnosis with duplex Doppler sonography

Duplex Doppler sonography of the axillary, subclavian, internal jugular, and brachiocephalic veins was performed in 20 normal volunteers and in a series of 22 consecutive patients with suspected venous thrombosis. When normal, these vessels had hypoechoic or anechoic lumina, sharply echogenic walls, and characteristic Doppler flow patterns that varied with changes in intrathoracic pressure. Most thrombosed vessels had poorly defined walls and echogenic lumina. All had absent flow on Doppler analysis. Duplex Doppler sonography was positive in all 10 patients subsequently shown to have venous thrombosis by venography or CT. One false-positive result occurred in a technically limited study. Sonography has the advantages of portability, ease of performance, and high patient acceptance. Duplex Doppler has advantages over either continuous-wave Doppler or imaging sonography alone. Our experience suggests that duplex Doppler sonography should be the initial diagnostic study in evaluating suspected thrombosis of the upper extremity thoracic inlet veins.     

Evaluation of topography and vascularization of cervical paragangliomas by magnetic resonance imaging and color duplex sonography

The management of cervical paragangliomas (PGs) depends on their specific type and their relation to adjacent vessels. The purpose of this study was to evaluate the potential of magnetic resonance imaging (MRI) and color duplex sonography (CDS) to classify PGs according to topography and vascularization. Sixteen patients harboring 22 PGs were studied retrospectively. With digital subtraction angiography as reference, the topographic relation of the tumors to the carotid arteries and the internal jugular vein and the patterns of vascularization were assessed. On MRI and CDS the typical feature of 15 carotid PGs was splaying of the carotid bifurcation, with the external carotid displaced anteriorly and the internal carotid artery and internal jugular vein located posteriorly. In five vagal PGs both modalities showed unidirectional anterior displacement of the external and internal carotid arteries. Two jugular PGs were found to extend within the lumen of the internal jugular vein. CDS completely depicted carotid body tumors but failed to delineate the high cervical portion of vagal and jugular PGs. MRI allowed us to assess the entire extent of all PGs. Nineteen lesions showed flow voids corresponding to abundant flow signal on CDS: three carotid body tumors appeared hypovascular on CDS and MRI. On CDS, intratumoral flow was directed cranially in carotid and inferiorly in vagal and jugular PGs. CDS and MRI are suitable for classification of cervical PGs as carotid, vagal or jugular PGs based on the topographic relation to the carotid arteries and internal jugular vein. Visualization of the intrinsic tumor vasculature proved an additional distinguishing criterion on CDS.     

Evaluation of coronary bypass grafts

Coronary artery bypass graft (CABG) surgery is in widespread use. Bypass graft angiography continues to be an integral part of the evaluation of the post-CABG patient. Future methods may include computed tomography and digital subtraction angiography to assist in this evaluation.     

Thoracic outlet syndrome: evaluation of the subclavian vessels by color duplex sonography.

Changes in flow in the subclavian artery and vein resulting from the use of a hyperabduction maneuver during Doppler sonography in 20 volunteers were compared with retrospective findings in 16 patients clinically suspected of having thoracic outlet syndrome. Significant compression of the subclavian artery showed in the Doppler waveform as at least a doubling of peak systolic velocity or complete cessation of flow with hyperabduction; significant compression of the subclavian vein was diagnosed by complete cessation of blood flow or loss of atrial and respiratory dynamics in the waveform of the subclavian vein with hyperabduction. In volunteers, asymptomatic compression of the subclavian vein with arm abduction was seen in two (10%) and asymptomatic compression of the subclavian artery was seen in four (20%). Of the 16 patients, thrombosis of the subclavian vein was found in seven, compression of the subclavian vein with hyperabduction was found in six, and diagnoses other than thoracic outlet syndrome were established as the cause of pain in three. When duplex sonography was compared with venography, which was performed in 10 patients, one false-negative case was found because a subclavian vein thrombus had not been detected. The subclavian artery was examined in five of the six patients with positional compression of the subclavian vein; compression of the subclavian artery was found in three. The clinical significance of compression of the subclavian artery cannot be determined from our data because of the small number of patients involved. When the sonographic criteria of subclavian vein clot or compression resulting in a complete loss of normal venous phasicity with arm abduction and the clinical criterion of subsequent improvement in symptoms after curative surgery are used, color Doppler sonography is 92% sensitive and 95% specific for the diagnosis of thoracic outlet syndrome. This preliminary study shows that Doppler sonography has potential in the evaluation of thoracic outlet syndrome.     

Evaluation of peripheral arterial bypass grafts with multi-detector row CT angiography: comparison with duplex US and digital subtraction angiography

PURPOSE: To assess the technical feasibility of multi-detector row computed tomographic (CT) angiography in the assessment of peripheral arterial bypass grafts and to evaluate its accuracy and reliability in the detection of graft-related complications, including graft stenosis, aneurysmal changes, and arteriovenous fistulas. MATERIALS AND METHODS: Four-channel multi-detector row CT angiography was performed in 65 consecutive patients with 85 peripheral arterial bypass grafts. Each bypass graft was divided into three segments (proximal anastomosis, course of the graft body, and distal anastomosis), resulting in 255 segments. Two readers evaluated all CT angiograms with regard to image quality and the presence of bypass graft-related abnormalities, including graft stenosis, aneurysmal changes, and arteriovenous fistulas. The results were compared with McNemar test with Bonferroni correction. CT attenuation values were recorded at five different locations from the inflow artery to the outflow artery of the bypass graft. These findings were compared with the findings at duplex ultrasonography (US) in 65 patients and the findings at conventional digital subtraction angiography (DSA) in 27. RESULTS: Image quality was rated as good or excellent in 250 (98%) and in 252 (99%) of 255 bypass segments, respectively. There was excellent agreement both between readers and between CT angiography and duplex US in the detection of graft stenosis, aneurysmal changes, and arteriovenous fistulas (kappa = 0.86-0.99). CT angiography and duplex US were compared with conventional DSA, and there was no statistically significant difference (P >.25) in sensitivity or specificity between CT angiography and duplex US for both readers for detection of hemodynamically significant bypass stenosis or occlusion, aneurysmal changes, or arteriovenous fistulas. Mean CT attenuation values ranged from 232 HU in the inflow artery to 281 HU in the outflow artery of the bypass graft. CONCLUSION: Multi-detector row CT angiography may be an accurate and reliable technique after duplex US in the assessment of peripheral arterial bypass grafts and detection of graft-related complications, including stenosis, aneurysmal changes, and arteriovenous fistulas.     

Role of color coded duplex sonography in the study of thyroid pathology. Personal experience

The authors examined 110 patients with suspected pathologic conditions of the thyroid by means of color-coded duplex US. In addition to the information yielded by conventional US, this technique allows organ vascularization to be demonstrated. Five normal patients were considered as a control group: no tissue vascularization was demonstrated in these cases. In 8 patients presenting with carcinoma or recurrences, vascularization was markedly increased both peripheral and central to the nodule. A few doubts are still to be solved as to the diagnostic value of color-coded duplex US in the evaluation of non-carcinomatous nodular pathologic conditions. As a matter of fact, non-functioning avascular adenomas can be demonstrated only in a very low percentage of cases (66%). Color-coded duplex US proved extremely sensitive and specific in depicting malignant neoplasms. Moreover, the use of fine-needle biopsy could be optimized and subsequently reduced. Color-coded duplex US proved to be markedly superior to other methods and techniques in the study of thyroid diseases, especially thyroiditis and multiple pathologic conditions. The simultaneous presence of hypocapture at scintigraphy and peripheral and central vascularization in a single nodule or within multinodular struma at color-Doppler was highly suggestive of malignant thyroid neoplasm. Color-coded duplex US is a low-cost technique, which can be performed on an outpatient basis. Moreover, it is not invasive, nor does it damage the thyroid. That is why its use is almost mandatory in the study of pathologic conditions of the thyroid.     

Cost-effectiveness of colour duplex sonography compared with angiography of the pelvis and lower limb

The present investigation was performed to assess the clinical consequences, utility and efficacy of colour duplex sonography (CDS) compared with angiography as a preoperative examination in aorta, pelvis and lower limb, and thus to estimate the cost-effectiveness of CDS. CDS was additionally performed in 53 consecutive patients referred for preoperative angiography of the lower limb. The results for 49 patients were reviewed and compared to assess the technique's clinical utility. The costs of the two methods and the consequences of inappropriate treatment were assessed. In 15 patients inadequate diagnoses were obtained at CDS. If surgery had been performed solely on the basis of the ultrasonographic diagnosis, repeat surgery would have been necessary in 9 patients. In a further 3 patients necessary surgery would not have been performed. Two patients would have been overtreated (unnecessary surgery instead of percutaneous transluminal balloon angioplasty). To correct the initial incorrect diagnosis the estimated yearly cost would be approximately 1.3 million Swedish crowns. In addition, complications and discomfort could be anticipated for the patients. Because of its low sensitivity CDS ist not cost-effective as a preoperative investigation of arteries of the pelvis and lower limb. Correspondence to: J. T. Geitung     

Lower-extremity vascular grafts placed for peripheral vascular disease: prospective evaluation with duplex Doppler sonography

Eighty-five men with 92 vascular grafts placed for peripheral vascular disease of the lower extremity underwent a total of 264 examinations with duplex Doppler over a 2.5-year period. In 64 patients who underwent more than one examination, the total follow-up encompassed 740 months. In 220 native femoral arteries (96.0%) the peak systolic velocity (PSV) was higher than that in the graft. Arteriovenous shunting was associated with a normal PSV and a markedly elevated diastolic component at spectral analysis. Focal fluid collections were common initially near the graft and usually disappeared uneventfully. An average PSV of 32 cm/sec or less was always associated with impending occlusion. The sensitivity of an average PSV of 40 cm/sec or less to indicate impending graft occlusion by the next visit was only 33%; the specificity, 94%. At initial examination, stenoses were associated with high PSV focally in the graft or low PSV with absent diastolic flow.     

Role of color duplex sonography in pre-operative internal mammary artery perforators assessment for breast reconstruction using contralateral lower pole flap

Reconstruction of a breast after mastectomy using the contralateral lower pole breast flap is an appealing procedure because it uses the tissues that were going to be excised during reduction of the sound breast to achieve symmetry. The literature mentioned that these flaps are supplied by the lower internal mammary artery perforators (IMAPs) with no further details.     

Evaluation of normal erectile function with color flow Doppler sonography

To understand better the vascular events that occur during normal erection, we used color flow Doppler sonography to examine the erectile process in seven normal subjects. The relationship of systolic/diastolic velocities and spectral waveform changes in the penile arteries was studied in response to increasing pressure within the corpora cavernosa (tumescence) before and after the intracorporal administration of drugs to induce erection. A characteristic spectral waveform pattern was identified throughout the erectile cycle, and the pattern was correlated with increasing pressure. Both systolic and diastolic velocities were elevated during the initiation of erection, at which time the pressure within the corpora cavernosa was low (11-25 mm Hg). Systolic velocities remained elevated until the last phase of erection (83-106 mm Hg). Diastolic velocity decreased as the intracorporal pressure increased from 25 to 40 mm Hg. Between 40 and 63 mm Hg, diastolic velocity approximated zero. With increasing pressure (63-83 mm Hg), diastolic flow reversed. As the corpora cavernosa approached full erection (83-105 mm Hg), both the forward systolic and reverse diastolic flow components diminished. At approximately 106 mm Hg (systolic occlusion pressure), flow ceased. Systolic/diastolic velocity and waveform phase relationships could be used to define the integrity of both the cavernosal artery inflow and the venous sinusoidal outflow occlusion mechanisms. Color flow Doppler sonography enhanced our ability to observe and quantify dynamic erectile events and provided new insights into understanding normal erectile function.     

Duplex sonography in the diagnosis of ischemic disease of the lower extremity. Comparative study with angiography

The aim was to study possibilities of duplex sonography in evaluation of ischemic diseases of the lower extremities. The results obtained were compared with angiographic findings and high correlation of the results was obtained. Duplex sonography is a simple, safe, noninvasive method in diagnosing the site and degree of stenotic changes on the arteries of the lower extremities.