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Biomedical subjects

A Goddi

Publications and source records attributed to A Goddi.

12 recordsLinked to original sources
PubMed2002

A new method to assess the fluidodynamic behaviour of an angiographic contrast agent.

PURPOSE: To propose a new method for the assessment of the fluidodynamic behaviour of angiographic contrast agents. The method enables measurement of the spatial distribution and time dependence of the contrast agent along a pseudo-vessel on images obtained with an X-ray image intensifier. MATERIAL AND METHODS: A particular phantom was devised consisting of a plexiglas box with an insert into which a latex tube with a 0.4 cm in diameter was placed in order to simulate the tortuous flow of a blood vessel. The box, which is filled with water to simulate the thickness of a normal patient, is connected to an injection and pumping system which serve to keep the contrast agent flowing in the pseudo-vessel tube. The pseudo-vessel tube was filled with plain water in one case and with saline solution in another case to assess their different dilution capabilities. The phantom and the flow of contrast agent were imaged with a conventional X-ray image intensifier system and the images were stored in digital format during 35 second acquisitions at a speed of 4 frames per second; for any frame it is possible to measure the mathematical contrast in any position in the image. Further, a diagram showing the time dependence of the spatial distribution of the mathematical contrast is proposed. The X axis shows the spatial distribution of the mathematical contrast, whereas the Y axis shows its temporal variation with a gray level proportional to the mathematical contrast value. By building an horizontal profile of this diagram one can obtain the spatial distribution at a fixed time, while by building a vertical profile one can obtain the temporal variation at a fixed point. Several different contrast agents were so tested. RESULTS: The proposed method allows different fluido-dynamic behaviour patterns of contrast agents and flowing media to be shown. Owing to the different chemical characteristics of water and saline solution these media have different dilution capabilities (higher for water) and this is well demonstrated by the diagram profiles obtained for each. The system has also allowed the detection of a particular behaviour of some contrast agents, whose spatial distribution was non uniform even in the last frames, thus showing a tendency to maintain their bolus-nature over time. An interesting feature which can be noticed in all the temporal profiles is the presence of a "pre-bolus", i.e. the contrast is higher at the very beginning of the flow, then decreases and after some time starts to increase again. Though the initial contrast value obviously depends on the iodine concentration employed, the method shows the contrast variation as a function of time is different for different contrast agents. CONCLUSIONS: The method and the equipment proposed provide a good description of the fluidodynamic behaviour of different contrast agents, but do not constitute a reference method for testing haemodynamic behaviour which, "in vivo", is obviously affected by several other chemical and metabolic factors. However, the method allows evaluation of the contrast agents from a physical and fluidodynamic point of view, showing that the iodine content is not the only feature affecting their behaviour. The method can be used in quality control to test the constancy of the physical behaviour of different contrast agents.

Angiography↗
PubMed2000

[Feasibility of the use of elastographic techniques with ultrasound in the diferentiation of different tissues].

PURPOSE: To investigate the feasibility of distinguishing different tissues by detecting their different elastic properties when mechanically stimulated with an ultrasound wide beam. MATERIAL AND METHODS: A tissue-mimicking material phantom was placed in a water filled box. Two devices (Teuco Hydrosonic) emitting two US beams (3.2 MHz) were placed on two opposite walls of the box. The US beams had a circular diameter of about 10 cm; their intensity could be set by varying the power voltage applied to the device from 0 to 12 V. The US beams caused a mechanical stimulation of both the phantom and the water surrounding it. An ATL HDI 5000 scanner was used in order to acquire tissue Color Doppler images using the fundamental frequency (Tissue Doppler Imaging, TDI), and the second harmonic (Harmonic Tissue Doppler Imaging, HTDI). The images allowed to visualize, using a color scale, the vibrational status of both the phantom and the water surrounding it. Both fundamental and second harmonic images were taken using different power values supplied to the stimulation device, with the voltage ranging from 0 to 12 V. In order to quantify the vibrational status of the water and of the tissue-mimicking phantom two Regions Of Interest (ROI) were taken on the images. A parameter describing the "color amount" in each ROI and defined by an appropriate mathematical function was proposed. RESULTS: Differences between the values of the "color amount" parameter in the phantom and in water were statistically significant both at the fundamental frequency and at second harmonic imaging, and for each positive value of the voltage of the power supplied to the device for the stimulation. Also the differences between the parameter "color amount" at the fundamental frequency and second harmonic imaging were statistically significant; the differences were found for both water and phantom and for any positive voltage. The correlation between the intensity of the stimulation (voltage) and the "color amount" parameter is statistically significant with the second harmonic technique in the phantom, nearly significant with the second harmonic technique in water and not significant in the other cases. CONCLUSIONS: It is possible to try to characterize a tissue by analyzing its elastic properties when an ultrasound wide beam mechanically stimulates it. The most promising technique consists in acquiring images using Harmonic Tissue Doppler Imaging, (HTDI) and measuring the vibrational status by using the "color amount" parameter proposed.

Elasticity↗
PubMed1999

[Study of ultrasonographic image textures with second-order statistical methods].

BACKGROUND: We report the sonographic image texture of the neonatal heart in different stages of development by calculating numerical parameters extracted from the gray scale cooccurrence matrix. To show pixel values differences and enhance texture structure, images were equalized, and then the gray level range was reduced to 16 to allow for sufficiently high occupancy frequency of the cooccurrence matrix. MATERIALS AND METHODS: We measured B-mode US images, all acquired with the same unit, using the same setup (gain, frequency, constant TGC). For each case measurements were made on 3 diastolic images by selecting a 32 x 64 pixel on the interventricular septum ROI. This procedure was applied to 3 different examinations made at birth, at 3 days, and after a month of life. For each 8 bit image we obtained a coocurrence matrix by sampling adjacent pixels at 0 degree, from which we calculated entropy; then the images were equalized and converted to 4 bit format; on these processed images we calculated 4 gray scale coocurrence matrix samplings adjacent pixels at angles of 0 degree, 45 degrees, 90 degrees, and 180 degrees. Parameters obtained from different angles cooccurrence matrix were averaged to get a numerical parameter independent of sampling angles. RESULTS: The one-way analysis of variance and Student's "t"-test were performed on the parameters obtained from 3 different examinations and the differences among different developmental stages are 95% significant. No significance was obtained comparing images at birth with those at 3 days. CONCLUSIONS: Differences are so little significant that they may be due to different factors affecting image texture and the variability introduced by manual ROI positioning; therefore no definitive conclusions can be drawn as to considering this kind of analysis capable of discriminating different stages of myocardial development. To apply this analysis to routine US examinations, different correction factors for range, azimuth, and focal dependence of texture must be considered.

Mathematics↗
PubMed1995

Diagnosis of pelvic masses with transabdominal color Doppler, CA 125 and ultrasonography.

BACKGROUND: The objective of this study was to test the accuracy of transabdominal color Doppler imaging in the prediction of malignancy of adnexal tumors when integrated in combination with CA 125 levels and two-dimensional ultrasound. METHODS: We considered 129 consecutive patients with a suspected adnexal mass at clinical examination and transabdominal and transvaginal two-dimensional ultrasound. Serum CA 125 was measured in all cases. All the patients underwent color Doppler imaging to measure the Resistance index of the tumor associated blood flow profile and then surgery and histologic diagnosis. RESULTS: The median age of the patients was 44 years (range 12-91), 64.3% were premenopausal and the prevalence of malignancy was 28.7%. The sensitivity of color Doppler mapping was 75.7%, specificity 71.7%, positive predictive value 68.3% and negative predictive value 93.0%, compared with 75.7%, 68.5%, 49.1% and 87.5% for CA 125 and 83.8%, 83.7%, 67.4% and 92.8% for two-dimensional ultrasound. Blood flow was undetectable by color Doppler imaging in 17 of the 129 cases (13.2%). In 55 patients with three concordant tests, the positive and negative predictive values were 100%. When CA 125 values and two dimensional ultrasound results were discordant (35 patients), the color Doppler diagnosis was correct in 88.6% of the cases (93% in premenopausal women). CONCLUSION: Color Doppler imaging alone is not better than two-dimensional ultrasound in predicting malignancy of pelvic masses. Its use together with CA 125 and two-dimensional ultrasound may improve the accuracy of predictions when the three tests are concordant or when the other two are discordant.

Adnexa Uteri↗
PubMed1994

Percutaneous cervical diskectomy: preliminary experience.

We assessed the feasibility of percutaneous treatment of a cervical herniated disc. In the lumbar region, the surgical instrument for percutaneous diskectomy passes only through the paravertebral muscles, while in the cervical region there is considerable risk of nervous, parenchymal and vascular lesions. Moreover, open surgery for cervical herniated nucleus pulposus is a well-established, low-risk procedure, with little risk of epidural fibrosis, the main complication of lumbar open surgery; a percutaneous procedure should therefore have a low morbidity rate. A safe percutaneous approach to cervical discs could be useful for biopsy and for treatment of high-risk patients for general anaesthesia. We treated 15 patients with cervical herniated nucleus pulposus; all gave informed consent and refused or were not eligible for open surgery. We used the Nucleotome described for treatment of lumbar herniated discs; except for the first three cases, we used colour Doppler sonography to detect hazardous structures in the path of the probe. We had one complication, a cervical haematoma due to damage to the inferior thyroid artery, prior to the use of ultrasound.

Cervical Vertebrae↗
PubMed1994

[Color Doppler ultrasonography versus angiography in leg aneurysms].

The authors compared color-Doppler US with angiographic findings in the study of peripheral lower limbs aneurysms. Twelve cases were observed over a 2-year period of time. In each case, the combination of B-mode and color-Doppler US permitted the accurate evaluation of the aneurysm and of the possible compression of adjacent vessels. Angiography, which was considered the gold standard, detected only 8 of 12 cases; in 3 of 8 cases, the actual diameter of the aneurysm was under estimated. The simultaneous visualization of vessel wall and of intraluminal blood flow proved color-Doppler US to be superior to the gold standard in these cases. The authors conclude that color-Doppler US may become the new reference standard in the diagnosis and follow-up of peripheral aneurysms.

Aged↗
PubMed1989

[Echo-guided renal biopsy in patients with a medical nephropathy].

Ninety-five percutaneous renal biopsies under ultrasound guidance were performed on 89 patients with nephrologic diseases. Accurate diagnosis was reached in 93% of cases at the first biopsy, and the figure increased to 100% after a second biopsy. The use of 18 and 16 gauge needles allowed correct histological diagnosis in 95% of patients, and satisfactory histology in the extant 5%. US guidance and the use of 18 and 16 gauge needles reduced the complications related to renal biopsy: in fact, severe hematuria occurred in 2 cases only.

Adolescent↗
PubMedDate not supplied

[Differential diagnosis of hematoma, pulsating hematoma and pseudoaneurysm of the femoral artery using color Doppler].

Color Doppler and Duplex Doppler US were employed on 4 patients with clinically suspected pseudoaneurysms as a complication of femoral artery puncture after cardiac catheterization. Pseudoaneurysms were identified with Color Doppler US and their typical appearance was confirmed. The grey-scale findings did not allow an adequate differentiation between hematoma and pulsed hematoma without fibrous encapsulation: only Color Doppler US easily detected the track between damaged artery and blood collection and allowed a sample to be obtained for pulsed Doppler examination. Color Doppler US allowed an accurate and non-invasive diagnosis of groin masses after femoral artery catheterization.

Aneurysm↗
PubMedDate not supplied

[Role of echography in the diagnosis of ovarian tumors].

The role of sonography is evaluated in the diagnosis of ovarian tumors. Real-time US proves more sensitive than gynecological examination in the diagnosis of ovarian diseases. As yet, however, no correlation has been found between histological findings and US appearance. An accurate review of the relative literature and of our results lead us to the conclusion that sonography does not significantly affect the early diagnosis of ovarian tumors.

Cystadenoma↗