Biomedical subjects

S Mussurakis

Publications and source records attributed to S Mussurakis.

24 records · Page 2Linked to original sources

PubMed1990

Compression ultrasonography as a reliable imaging monitor in deep venous thrombosis.

Our experience at Hippokration Athens Hospital with high-resolution real-time ultrasonography of the deep veins of the lower extremities is described, drawn from the results of a prospective comparative study of 65 patients. We used a combination of sonography and contrast venography for the detection of deep venous thrombosis (DVT). Of the study group, 33 had clinically suspected DVT, 20 were asymptomatic high-risk patients, while 12 with varicosities of the leg and scheduled for saphenectomy were examined preoperatively for deep venous patency confirmation. For all patients, venography, the reference method, was performed within 12 hours of the ultrasound scan. Since 29 of the examinations were bilateral, the total number of extremities studied was 94. The sonographic criteria analyzed were the intraluminal echogenicity and the venous compressibility with the ultrasound transducer probe. In addition, the response of the common femoral vein to the Valsalva maneuver was studied. Among these three criteria, compressibility was by far the most accurate. Noncompressible abnormal veins were noted in all of the 24 extremities with proximal thrombosis and in six of the 12 with thrombosis limited to the calf veins. Thus, the sensitivity of the compressibility criterion was 100 per cent for proximal and 50 per cent for isolated calf venous thrombosis (83 per cent). All venographically patent veins were fully compressible (specificity, 100 per cent). Abnormal intraluminal echoes were found in 18 of the 36 extremities with thrombosis but not in those with negative findings on venography. Sensitivity of intraluminal echogenicity was, therefore, 50 per cent and specificity, 100 per cent. For the Valsalva criterion, the standard lower normal limit of 10 per cent was applied, leading to 40 per cent sensitivity and 93 per cent specificity rates. In comparison with venography, ultrasonography underestimated the extent of thrombosis in 60 per cent of the true-positive examinations, although never to a clinically significant degree. In conclusion, compression ultrasonography, a technique based upon the unique criterion of venous compressibility, is a highly accurate and objective noninvasive diagnostic method, and is also suitable as a screening test. We urge clinicians to support their therapeutic decisions concerning the management of DVT with it.

Adult↗

PubMedDate not supplied

Microvessel density of invasive breast cancer assessed by dynamic Gd-DTPA enhanced MRI.

It has been postulated that the rapid enhancement demonstrated by breast carcinomas after administration of contrast media is a direct result of tumor angiogenesis. However, to date, little quantitative data have been published to support this view. A retrospective study has been undertaken to compare dynamic contrast-enhanced data obtained from 40 patients with microvessel density (MVD) evaluated in specimens immunohistochemically stained with a factor VIII related antigen. The dynamic data were analyzed quantitatively using both simple indices of enhancement and a two-compartment kinetic model. A moderate but significant correlation was demonstrated between initial enhancement and MVD, and this correlation strengthened when node-positive tumors were considered in isolation (r = .77, P < .0005). However, the data showed considerable variability. The enhancement characteristics of the tumors could not be explained solely by their MVD; therefore, MRI cannot be used to predict MVD in vivo. Further work is required to address the exact relationship between contrast-enhanced MRI and tumor angiogenesis.

Adult↗

PubMedDate not supplied

Combined superficial peroneal and saphenous nerve block for ascending venography.

Needle insertions into the veins of the dorsum of the foot are an overlooked source of pain and discomfort during ascending venography. As a solution to this problem a regional anaesthetic technique is presented, the combined superficial peroneal and saphenous nerve block, after being studied prospectively on 42 patients referred for bilateral venography. The nerve blocks were always performed unilaterally. At the end of each bilateral study patients were asked to express a preference for one of the two venograms, on the basis of pain and discomfort from the needle insertions. Of the 42 patients, 27 (64.3%) opted for venography with regional anaesthesia, 9 (21.4%) for venography without regional anaesthesia, while 6 (14.3%) did not state a definite preference. As shown by the sign test, preference for venography with venography with regional anaesthesia was highly significant. By observing the reactions of the patients during the needle insertions, the radiologist classified arbitrarily the pain produced in each individual venogram as minimal, moderate or severe. The statistical significance of these observations was verified with the chi-squared test for trend and the sign test. In addition to diminishing effectively the pain from the venography needle, this simple technique proved to be safe and causing negligible discomfort. It is recommended for all patients who are apprehensive or have already experienced considerable pain on a first unsuccessful venipuncture attempt, or when multiple punctures are expected because of lack of suitable veins or presence of oedema.

Adult↗

PubMedDate not supplied

Dynamic MRI of invasive breast cancer: assessment of three region-of-interest analysis methods.

PURPOSE: In this study, three region-of-interest (ROI) analysis methods based on operator-defined and semiautomated sampling of pharmacokinetic breast maps of contrast uptake are described. The observer variability and impact of the methods on the estimated enhancement characteristics of invasive cancer are also presented. METHOD: Fifty-four women with invasive breast cancer underwent dynamic Gd-DTPA-enhanced MRI. ROIs were drawn by two observers on parametric images obtained from compartmental modeling of the dynamic data. Three methods were used: (a) An irregular ROI was drawn to include as much of the enhancing part of the tumor as possible (large ROI); (b) a 12 pixel circular ROI was placed at the most rapidly enhancing part of the large region (small ROI); and (c) a computer algorithm interrogated the large region pixel by pixel using a 9 pixel square mask and selected the region with the highest mean parameter value (semiautomated ROI). RESULTS: Significant observer variability and bias were found in the enhancement measurements using the large ROI method. There was no observer bias associated with the other methods, but the variability of the small ROI method was substantial. An almost perfect observer agreement was achieved using the semiautomated method. The small and semiautomated ROI methods produced significantly higher enhancement ratios than the large ROI method, especially in grade III carcinomas. CONCLUSION: Variability is inherent in subjective ROI analysis, but the semiautomated method of ROI selection and sampling of parameter images of the breast is an efficient and reliable alternative that may allow better standardization of the MR technique.

Adult↗

PubMedDate not supplied

Peripheral enhancement and spatial contrast uptake heterogeneity of primary breast tumours: quantitative assessment with dynamic MRI.

PURPOSE: The purpose of our study was to determine if quantitative analysis of peripheral enhancement and spatial contrast uptake heterogeneity is useful in the characterisation of abnormalities seen at breast MRI. METHOD: Ninety-one women underwent dynamic gadolinium-enhanced breast MRI. Regions of interest were processed by a parallel thinning algorithm to define central and peripheral subregions of lesions. Peripheral enhancement was quantified at every time point of the dynamic sequence as a signal difference-to-noise ratio. Moreover, a radiologist assessed the images for the presence of peripheral enhancement and classified the regional and subregional time-intensity profiles of each lesion. RESULTS: Sixty-four invasive carcinomas and 30 benign lesions were analysed. Significant differences were found between benign and malignant lesions in peripheral enhancement as determined from the dynamic images (p = 0.0002; sensitivity, 0.34; specificity, 1.00) in time-intensity profiles (p < 0.000005; sensitivity, 0.67; specificity, 0.93) and in peripheral percentage signal changes at 1 min postcontrast (p = 0.001). There was a much higher relative signal increase centrally than peripherally (p < 0.0005), but peripheral signal changes had greater diagnostic value than central ones (Az = 0.72 vs. 0.63; p = 0.02). Carcinomas showed higher peripheral enhancement than benign lesions (p = 0.001). Peripheral enhancement reached maximum diagnostic value at 4 min postcontrast (Az = 0.80) and performed best as a highly sensitive but moderately specific diagnostic index. CONCLUSION: Quantification of peripheral enhancement is diagnostically useful and offers insight into the enhancement mechanisms encountered in breast MRI. Primary breast tumours show substantial spatial contrast uptake heterogeneity. Lesion differentiation based on percentage signal changes is improved by restricting sampling to the periphery of tumours.

Adult↗

PubMedDate not supplied

Effect of temporal resolution on the diagnostic efficacy of contrast-enhanced MRI in the conservatively treated breast.

PURPOSE: Our goal was to assess the effect of image acquisition rate on the diagnostic efficacy of contrast-enhanced MRI in the conservatively treated breast. METHOD: Sixty-seven women, treated with breast-conserving surgery and radiotherapy for early-stage breast cancer, were imaged at 1.5 T using a dynamic contrast-enhanced sequence with a temporal resolution of 12 s. Enhancement was recorded over time for the dominant lesion in each patient. Data were subsequently removed to simulate various acquisition rates and the enhancement indexes of benign and malignant lesions were compared. RESULTS: Seventeen patients had confirmed local recurrence and 50 remained disease-free. There were significant differences in the enhancement indexes of benign and malignant lesions 24-264 s after contrast agent administration. Acquisition rate had a negligible effect upon diagnostic efficacy. CONCLUSION: Two image data sets collected before contrast agent administration and between 1.5 and 3.5 min afterward may be sufficient to differentiate recurrent and benign disease.

Adult↗