The value of pre-operative ultrasound mapping of the greater saphenous vein prior to 'closed' in situ bypass operations

Objective: The aim of this study was to test pre-operative ultrasound mapping for the detection of duplications and narrow vein segments of the greater saphenous vein (GSV) used as bypass for occlusive arterial disease surgery. Patients and methods: In 44 patients pre-operative ultrasound findings of duplications and lumen assessment of the GSV were compared to the per-operative findings. Results: In nine patients (20%) the pre-operative ultrasound examination showed a duplication. Pre-operative ultrasound had missed a duplication in two cases but had instead shown a narrow segment in both. The pre-operative ultrasound assessment of lumen diameter showed a narrow lumen segment in 10 of the 44 patients. In one patient a per-operatively narrow lumen had not been seen on pre-operative ultrasound. Conclusion: Pre-operative ultrasound mapping of the GSV is a sensitive tool for detection of duplications and narrow vein segments. Since these anatomical variations provide important information for the vascular surgeon, before performing a 'closed' in situ bypass operation, pre-operative vein mapping should be considered when planning such a procedure

Temporal averaging for quantification of lumen dimensions in intravascular ultrasound images

Quantitative analysis of arterial dimensions from high frequency intravascular ultrasound images (30 MHz) may be hampered by strong blood scattering. Replacement of blood by saline is one method to provide a clear view of the arterial lumen; another method is that of temporal averaging of successive ultrasound images. The accuracy of this latter method was tested by comparing the lumen area measurements on the temporal-averaged image, with the data of the same cross-section obtained from the single-frame and saline-filled images. The mean lumen area measured on the temporal-averaged images was similar to that measured on the single-frame images (mean difference: −0.02 ± 1.16 mm2; p = ns). The mean lumen a

Detection of vascular morphology by high frequency intravascular ultrasonic imaging

This study was designed to validate the potential clinical utility of intravascular ultrasonic imaging in vitro and in vivo. In vitro studies were performed to assess the accuracy of dimensional and morphological information. In vitro images of human vessels (n = 75) demonstrated that lesion thickness determined echographically closely related with histological samples (r = 0.83). Morphologically, muscular and elastic arteries could be distinguished echographically based on the echogenicity of the arterial media. Close relation was also found in the morphological subtypes of atherosclerosis. Subsequently, intravascular ultrasound was used percutaneously in vivo in 20 patients to obtain images of the iliac and superficial femoral artery. High quality real-time images were obtained. Normal vessels were seen showing pulsatile circular images with a hypoechoic muscular media resulting in a typical three-layered appearance. Diseased arteries revealed non-obstructive and obstructive lumen. At the site of obstruction thinning of the muscular media was evident. Pulsation was not always present. Following dilatation of the obstructive lesion using balloon angioplasty the ultrasonic cross-sections changed drastically revealing plaque rupture, dissection, plaque-free wall rupture, rest stenosis and oedema. We conclude that intravascular ultrasonic imaging is a promising technique to document accurate dimensional and morphological characteristics of human vascular disease for guidance of therapeutic interventions

Discrimination of intravascular lumen and dissections in single intravascular ultrasound images using subtraction, conventional averaging and saline flush

With current 30-MHz intravascular ultrasound systems, flowing blood may cause considerable backscatter which in real-time images is characterized by dynamic speckle. However, in a single intravascular ultrasound image (still-frame) the discrimination between arterial lumen and wall may be difficult due to the frozen intraluminal speckle, particularly in the presence of dissections. We compared subtraction, averaging and saline flush as methods to improve the discrimination between arterial lumen and wall in a single image. The real-time images served as gold standard. In 22 patients who underwent peripheral balloon angioplasty, ultrasound images obtained from 84 sites were examined. The sensitivity and specificity of detecting dissections were in the subtraction image 85% and 100%, in the averaged image 57% and 96%, and in the saline flush image 58% and 86%, respectively. Subtraction is a promising method to outline the irregular lumen in a single image

Intravascular ultrasound predictors of outcome after peripheral balloon angioplasty

Objective:This study investigates the potential role of intravascular ultrasound (IVUS) in the outcome in patients undergoing percutaneous transluminal angioplasty (PTA) of the superficial femoral artery.Materials:Angiographic and the qualitative and quantitative IVUS data obtained at the narrowest site derived from 39 patients before and after PTA were analysed.Results:Angiographically the diameter of the remaining stenosis seen after PTA was classified as < 50% in 31 patients (success); in eight patients a failure was encountered. Evaluating at 6 months the functional and anatomic results of the PTA in 31 patients, the intervention was a success in 14 patients (Group I) and a failure in 17 patients (Group II). The remaining eight patients defined as angiographic failure following PTA comprised Group III. Neither qualitative nor quantitative IVUS data obtained before PTA could predict outcome. Conversely, after PTA, the extent of dissection was significantly more severe in Groups II and III than in Group I. Similarly, significant differences were found between Groups I and II for mean free lumen area (13.2 vs. 9.7 mm2, respectively) and mean free lumen diameter (4.1 vs. 3.5 mm, respectively). Quantitative data obtained in Group II were similar to those in Group III.Conclusion:This preliminary study demonstrates that following PTA the extent of dissection, free lumen area and diameter seen with IVUS are predictive factors of patency. Future studies with more patients are mandatory to further highlight the sensitivity of these observations

Validation of quantitative analysis of intravascular ultrasound images

This study investigated the accuracy and reproducibility of a computer-aided method for quantification of intravascular ultrasound. The computer analysis system was developed on an IBM compatible PC/AT equipped with a framegrabber. The quantitative assessment of lumen area, lesion area and percent area obstruction was performed by tracing the boundaries of the free lumen and original lumen. Accuracy of the analysis system was tested in a phantom study. Echographic measurements of lumen and lesion area derived from 16 arterial specimens were compared with data obtained by histology. The differences in lesion area measurements between histology and ultrasound were minimal (mean ± SD: -0.27±1.79 mm2, p>0.05). Lumen area measurements from histology were significantly smaller than those with ultrasound due to mechanical deformation of histologic specimens (-5.38±5.09 mm2, p0.05). Finally, intra- and interobserver variability of our quantitative method was evaluated in measurements of 100 in vivo ultrasound images. The results showed that variations in lumen area measurements were low (5%) whereas variations in lesion area and percent area obstruction were relatively high (13%, 10%, respectively). Results of this study indicate that our quantitative method provides accurate and reproducible measurements of lumen and lesion area. Thus, intravascular ultrasound can be used for clinical investigation, including assessment of vascular stenosis and evaluation of therapeutic intervention

Effect of balloon angioplasty in femoropopliteal arteries assessed by intravascular ultrasound

Objective: To study the effects of balloon angioplasty (PTA) of the femoropopliteal artery with intravascular ultrasound (IVUS). Materials and methods: Corresponding IVUS cross-sections (n = 1033) obtained before and after PTA from 115 procedures were analysed. Vascular damage including plaque rupture, dissection and media rupture was assessed. Free lumen area (FLA), media-bounded area (MBA) and plaque area (PLA) were measured. Results: After PTA vascular damage was seen at the target site in 83 (72%) arteries: plaque rupture in 30 (26%), dissection in 66 (57%) and media rupture in 20 (17%) arteries. The FLA increased from 5.4 ± 3.4 mm2 to 14.1 ± 5.0 mm2 (p < 0.001), MBA increased from 26.9 ± 10.0 mm2 to 32.9 ± 10.7 mm2 (p < 0.001) and PLA decreased from 21.6 ± 8.5 mm2 to 18.8 ± 8.0 mm2 (p < 0.001). The increase in MBA accounted for 68% of lumen gain. The frequency of vascular damage and the relative contribution of MBA increase and PLA decrease to luminal gain were not different in procedures with balloon diameter ≤ 5 mm and ≤ 6 mm. Conclusions: Vascular damage is common following PTA. Lumen gain is mainly due to vessel expansion and, to a lesser extent, to a decrease in plaque area