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Biomedical subjects

S Delorme

Publications and source records attributed to S Delorme.

16 recordsLinked to original sources
PubMed1996

Imaging of abdominal nodal spread in malignant disease.

This is a review of the role of imaging procedures for the assessment of abdominal and pelvic lymph nodes. The diagnosis of malignant lymphatic spread is rarely the sole purpose of imaging, because it is usually part of a general abdominal examination, most frequently with CT or US, or increasingly with MRI. These studies are often requested in order to obtain information about the situation to be encountered during surgery, or to alert the surgeon to irresectability or to unexpected metastases outside the initially planned area of exploration. In most surgically treated tumours the role of imaging for preoperative staging is limited, due either to its insufficient sensitivity or because the initial treatment is independent of the lymph node stage. Imaging is commonly used to verify treatment response to chemo or radiotherapy and for follow-up.

Abdominal Neoplasms↗
PubMed1996

[Cui bono? Comments on cost-benefit analysis in ultrasound diagnosis].

Despite the low costs of a single examination, the overall expenses for ultrasonography are exceptionally high (1.4 billion DM in 1993), not counting the costs of further examinations because of unclear findings. The advantages of sonography are that it is harmless and yields diagnostically important results. Its clinical benefit is beyond doubt in the case of acute clinical symptoms, but unclear for staging and followup of malignant tumors. It has been shown to be efficient in screening for renal and prostatic cancer. Here, the costs for sonographic screening appear to be potentially outweighed by the reduction in treatment expenses. However, the cost of sonographic examinations can sometimes be avoided: sonography should not be used if there is no clear indication or if the examiner is not really qualified or the equipment is insufficient. There is a conflict of interest when the referring physician performs to sonography himself, leading to unnecessary examinations. To limit costs it would be potentially helpful if sonographic examinations are only performed when the indications are valid. The education of the examining physicians must be improved, better equipment must be used, scanners can be shared, and patients can be referred to colleagues who are more experienced in sonography. The currently reformed reimbursement scheme is of little value because it does not permit a qualified, thorough, cost-efficient examination.

Cost-Benefit Analysis↗
PubMed1995

Quantification of color Doppler for the evaluation of tissue vascularization.

Assessment of tissue vascularization with color Doppler (CD) can improve differential diagnosis of tumors. Until now, measurement of flow velocities is restricted to conventional duplex ultrasound of single vessels or semiquantitative scoring of the vessel distribution in CD. We developed a new method for quantification of CD data in organs or tumors by statistical image analysis. Based on standardized image recording, data is acquired from the video output of any ultrasound scanner using a 24-bit color framegrabber in a personal computer. The digitized colors are recognized according to their position in the CD palette bar resulting in an 8-bit color image (number of identified pixels > 99.9%). Within the region of interest, statistics of the detected flow patterns are calculated. The color pixel density and the mean color value varies between recordings of the same image during subsequent systolic peaks with a SD of 10% and 2%, respectively, and within different sections of the same organ or tumor with 25% and 10-50%. This analysis can be used for comparative or longitudinal studies and an objective evaluation of CD in complex vascular formations such as tumors. Its diagnostic impact has already been demonstrated in clinical studies.

Blood Flow Velocity↗
PubMed1995

[Effects of viscosity, cannula size and temperature in mechanical contrast media administration in CT and magnetic resonance tomography].

PURPOSE: Mechanical contrast media application is used to improve image quality and allow better quantitative assessment of the contrast media kinetics for CT as well as MRI. The pressure within the i.v. line system must be known to enable safe and quantitatively exact application. MATERIAL AND METHODS: Experimental setup to analyse the inline pressure, the storage volume as well as the exactness of delivery within the i.v. line system was prepared. Representative contrast media Ultravist 300, Ultravist 370, Magnevist and Conray 60 as well as 0.9% NaCl were measured with ten different flow rates from 0.1 ml/sec to 5.0 ml/sec using the six most common i.v. cannula sizes (22G-14G). RESULTS: System pressures between 38-60 psi (maximum allowed system pressure = 60 psi) are commonly obtained with standard sizes of i.v. cannulas, such as an 18 G cannula and flow rates > or = 2.5 ml/sec using Ultravist 300 (viscosity 13 mPa.s at 20 degrees C). Higher system pressures (> 25 psi) produce an exponential increase of the storage volume within the i.v. line system. The additional storage volume within the i.v. line tubing (d = 2.9 mm, 76 shore) is at 60 psi and 20 degrees C 5 ml/m, and at 37 degrees C 11 ml/m in addition to the volume of the tubing of 7 ml/m. CONCLUSION: Based on the measured data, both the minimum and the recommended sizes of the i.v. cannulas in respect of flow rate and viscosity of the used contrast media were compiled for system pressures at < or = 60 psi as well as < or = 38 psi.

Catheterization↗
PubMed1994

Breast tumors: computer-assisted quantitative assessment with color Doppler US.

PURPOSE: To compare quantified measurements with color Doppler ultrasonography (US) with those obtained with conventional duplex US in the differential diagnosis of suspect lesions in the breast. MATERIALS AND METHODS: A computer-assisted protocol was used to calculate the color pixel density (CPD) and the mean color value (MCV) in US images of breast lesions. These results were compared with conventional results in the examination of 25 patients (aged 29-78 years) with carcinomas and 32 patients (aged 23-73 years) with benign lesions of the breast. RESULTS: The sensitivity of maximum flow velocity in helping identify carcinomas was 60% and the specificity was 70%. In color Doppler US, the sensitivity for MCV in helping identify carcinomas was 92% and the specificity was 78%; for CPD the sensitivity was 64% and the specificity was 91%. Combining MCV and CPD did not improve differentiation. CONCLUSION: Computer-assisted image analysis may be superior to conventional duplex US in helping differentiate between carcinomas and benign lesions.

Adult↗
PubMed1994

[Comparison of computerized tomography and B-image ultrasound in imaging diagnosis of the mediastinum].

40 patients with suspected mediastinal tumors were independently examined with computed tomography (CT) and sonography. The findings were confirmed by bronchoscopy, mediastinoscopy or surgery. In the assessment of the upper and middle mediastinum, sonography reaches a high sensitivity. On the contrary, in the evaluation of the anterior and posterior mediastinum, sonography is clearly inferior to CT. 90% of the tumors demonstrated by CT could be assessed with sonography. The most frequent tumors can be diagnosed with ultrasound. The evaluation of tumors in the paravertebral and retrosternal space is limited. Sonography of the mediastinum is a noninvasive, well-reproducible and cost-effective imaging modality that provides important information in cases of unclear X-ray and CT findings. The preliminary results encourage to a more frequent use of mediastinal sonography.

Adult↗
PubMed1993

[Sonography of enlarged cervical lymph nodes].

In this article, the current role of ultrasonography in the evaluation of enlarged lymph nodes of the neck is reviewed with particular regard to the identification of malignant changes. Morphological changes in malignant lymph node involvement are discussed. The differentiation of benign and malignant changes is based mainly on criteria like size, shape, capsule penetration and vessel infiltration. New methods like color Doppler sonography and computer-aided tissue characterization will be discussed.

Biopsy, Needle↗
PubMed1993

[Doppler sonography of breast cancer].

The article gives a review of the pathophysiology of tumour vascularity and currently available methods of Doppler sonography. The advantages and limitations of continuous wave Doppler, duplex Doppler and colour-coded Doppler sonography are discussed. Current results, including our own personal experience, show that Doppler sonography does not yet provide sufficient proof of malignancy or benignity. The quantification of tumour vascularity for prognostic reasons or for therapy planning and monitoring may be another potential application of Doppler sonography. New methods are now available for quantitative evaluation. Their validity, however, remains to be determined.

Breast Neoplasms↗
PubMed1992

[Recurrence paralysis: computed tomographic analysis of intrathoracic findings].

The long and singular course of the inferior (recurrent) laryngeal nerve makes it very vulnerable to infiltration by tumors of various locations. In particular, mediastinal and pulmonary lesions must be considered in the case of left vocal chord palsy. Recurrent nerve paralysis caused by a tumor indicates advanced disease. We retrospectively reviewed the computed tomography (CT) findings in 29 patients with bronchogenic carcinoma or mediastinal tumors and recurrent nerve paralysis with respect to the site, size and extent of the tumor and the lymph node status. The review revealed a marked predominance of left upper lobe tumors with extensive lymph node metastases to the anterior mediastinum and the aortopulmonary window. The extent of mediastinal involvement exceeded the average involvement in a control group of 30 randomly selected patients with bronchogenic carcinoma at the time of presentation. In all patients CT demonstrated tumor tissue which could have caused the paralysis at one or more sites along the anatomical course of the recurrent nerve. In most cases the tumor was located at the aortic arch. The left paratracheal region, right paratracheal region and right pulmonary apex were affected in one case each. We conclude that in patients with cancer, CT is a suitable method for localizing a recurrent nerve lesion.

Carcinoma, Bronchogenic↗
PubMed1992

[Sonography of renal cell carcinoma].

The value of routine abdominal ultrasonography in the detection and the staging of renal cell carcinoma is described. The sonomorphologic criteria of small and large renal cell carcinomas and the potential and the limitations of pulse and colour Doppler in the evaluation of malignancy are presented. An overview of the most important conditions that need to be considered in the differential diagnosis is given. The possibilities of ultrasonic staging and follow-up after nephrectomy are mentioned. The results of multiple different studies dealing with the increased frequency of serendipitous detection of renal cell carcinoma are listed, and the consequent importance of renal ultrasonography for screening is discussed.

Carcinoma, Renal Cell↗
PubMed1991

[Computed tomography of the upper mediastinum. Optimized contrast media application by the use of an infusion pump].

The aim of this study is to show the advantages of a power injector for contrast media application in comparison to manual bolus injection. The evaluation of 144 studies showed significant improvements for the examinations using the power injector based on densitometry in selected vessels (average enhancement 348 vs 280%) as well as subjective evaluation of contrast quality (3.4 pts vs 2.3 pts on a subjective scale) and contrast-induced artifacts (1.8 vs 2.3 on a subjective intensity scale). All parameters show that an increased, more reliable, and homogeneous enhancement can be obtained by application of the power injector compared to manual bolus injection technique using the same amount of contrast media (100 cc). Due to the possible standardisation of this technique, the results are reproducible. Increased reliability in expected diagnostic gain can be obtained using our technique for intravenous contrast application. This introduced technique requires no additional monetary or time expense and is therefore applicable for clinical routine work.

Contrast Media↗
PubMedDate not supplied

Quantitative characterization of color Doppler images: reproducibility, accuracy, and limitations.

A computer-based quantitative analysis for color Doppler images of complex vascular formations is presented. The red-green-blue-signal from an Acuson XP10 is frame-grabbed and digitized. By matching each image pixel with the color bar, color pixels are identified and assigned to the corresponding flow velocity (color value). Data analysis consists of delineation of a region of interest and calculation of the relative number of color pixels in this region (color pixel density) as well as the mean color value. The mean color value was compared to flow velocities in a flow phantom. The thyroid and carotid artery in a volunteer were repeatedly examined by a single examiner to assess intra-observer variability. The thyroids in five healthy controls were examined by three experienced physicians to assess the extent of inter-observer variability and observer bias. The correlation between the mean color value and flow velocity ranged from 0.94 to 0.96 for a range of velocities determined by pulse repetition frequency. The average deviation of the mean color value from the flow velocity was 22% to 41%, depending on the selected pulse repetition frequency (range of deviations, -46% to +66%). Flow velocity was underestimated with inadequately low pulse repetition frequency, or inadequately high reject threshold. An overestimation occurred with inadequately high pulse repetition frequency. The highest intra-observer variability was 22% (relative standard deviation) for the color pixel density, and 9.1% for the mean color value. The inter-observer variation was approximately 30% for the color pixel density, and 20% for the mean color value. In conclusion, computer assisted image analysis permits an objective description of color Doppler images. However, the user must be aware that image acquisition under in vivo conditions as well as physical and instrumental factors may considerably influence the results.

Algorithms↗
PubMedDate not supplied

An optimized examination protocol for contrast-enhanced cervical and mediastinal CT.

We compared an optimized contrast-enhanced CT technique for the neck and upper mediastinum with a conventional technique and with nonenhanced images, using densitometric measurements. The optimized protocol included slice thickness, infusion rate, postural maneuvers, and manipulation of the gantry tilt. Densitometric evaluation showed significantly higher enhancement values in vessels and metastases with the optimized protocol than with conventional technique, without significant enhancement in muscle. Semiquantitative assessment demonstrated significantly better image quality with the optimized protocol. The optimized technique has been implemented into routine use.

Absorptiometry, Photon↗