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R Righetti

Publications and source records attributed to R Righetti.

16 recordsLinked to original sources
PubMed2004

An experimental characterization of elastographic spatial resolution: analysis of the trade-offs between spatial resolution and contrast-to-noise ratio.

An experimental study of the spatial resolution in elastography was conducted. Models that involved two cylindrical inclusions arranged as a wedge were used to characterize the axial and lateral resolution of the axial strain elastograms. A study of the dependence of the spatial resolution on several factors such as the algorithmic parameters, the applied strain and the modulus contrast was performed. The axial resolution was found to show a linear dependence with respect to the algorithmic parameters, namely the window length and the window shift used for strain estimation. The lateral resolution showed a weak dependence on the algorithmic parameters. A weak dependence of the spatial resolution on factors such as the modulus contrast and the applied strain was found. The trade-offs between the spatial resolution and the elastographic contrast-to-noise ratio (CNR(e)) were then analyzed. A nonlinear trade-off between the CNR(e) and the axial and lateral resolution was shown for conventional strain estimation techniques, with the CNR(e) improving at a more than linear rate with respect to a linear degradation in the resolution. This study provided an experimental framework for characterizing the spatial resolution in elastography and facilitating a comparison of the CNR(e) with spatial resolution.

Elasticity↗
PubMed2003

Trade-offs between the axial resolution and the signal-to-noise ratio in elastography.

Elastography involves tracking the ultrasonic A-mode signals before and after mechanical compression of tissue to form a computed image of the local strains undergone by various tissue components. The quality of the strain estimates in elastography is typically quantified using factors such as the elastographic SNR (SNR(e)), contrast-to-noise ratio (CNR(e)), and the spatial resolution. These quality factors depend on the mechanical parameters (such as the applied strain and the boundary conditions), the acoustic parameters (such as the sonographic SNR, the center frequency, and the bandwidth), and the signal-processing parameters (such as the window length and the window separation). Theoretical developments in elastography have established functional relationships between the SNR(e) and CNR(e) and these parameters. Similarly, simulations have established empirical relationships between the axial resolution and the acoustic and signal-processing parameters. We find that a trade-off exists between the achievable SNR(e) (CNR(e)) and the axial resolution in elastography and that the trade-off occurs only with respect to the signal-processing parameters. Theoretical work on the spatial resolution accompanied with simulations and experiments were used to confirm such an observation. The trade-off between the SNR(e) (CNR(e)) and the resolution was found to be nonlinear, with large improvements in the SNR(e) being possible at the expense of small reductions in the axial resolution. All the quality factors improve with the acoustic parameters, which suggests the preferred use of transducers with high absolute bandwidths and center frequencies.

Acoustics↗
PubMed2002

Antegrade scrotal sclerotherapy in the treatment of varicocele: a prospective study.

OBJECTIVE: To assess the results of our experience in correcting primary varicocele using a modified technique of antegrade scrotal sclerotherapy. PATIENTS AND METHODS: From December 1997 to February 2000, 201 patients with primary varicocele underwent antegrade scrotal sclerotherapy. Before treatment all patients were evaluated by a physical examination, colour Doppler ultrasonography of the spermatic cord, and abdominal and scrotal ultrasonography. Sperm samples were analysed only in patients aged > 18 years. The treatment was administered using a special venous catheter system with a Y-adapter. Complications after treatment and the rate of persistence of reflux were assessed 3 and 6 months after the antegrade scrotal treatment, by clinical examination and colour-Doppler ultrasonography of the spermatic cord. RESULTS: The mean operative duration was 15 min; there were no significant complications during treatment and all patients were discharged within 4 h. Complications after treatment occurred in 10 of the 201 patients (5%); four patients had epididymo-orchitis, three a scrotal haematoma, one a surgical wound infection, one persistent scrotal pain and one persistent flank pain on the same side as the surgery. Reflux was persistent in 12 patients (6%). CONCLUSIONS: Antegrade scrotal sclerotherapy is a simple, minimally invasive and highly effective technique for blocking spermatic vein reflux, with a low rate of complications. The technical changes simplified the cannulation of the spermatic vein and facilitated antegrade phlebography and sclerotherapy using the air-block technique.

Adolescent↗
PubMed2001

Primary lymphoma of the epididymis: case report and review of the literature.

OBJECTIVE: To report an extremely rare clinical pathological observation of a case of primary lymphoma of the epididymis, without testicular or systemic involvement, and to update the relevant literature. MATERIALS AND METHODS: A 25-year-old white male patient complaining of right scrotal pain was referred to our department. Clinical examination detected a hard painful mass at the right epididymal head. Epididymitis was diagnosed and conservative therapy with antibiotics and anti-inflammatory drugs was given. After 2 months of therapy the patient was admitted to our department because a tumor was suspected. Tumor markers were normal. Right scrotal exploration was performed through a standard inguinal incision. The epididymal head was completely replaced by a hard white mass. Fresh frozen sections indicated a malignant tumor. Right radical orchiectomy was performed. RESULTS: High-grade primary epididymal non-Hodgkin's lymphoma with diffuse large cells (group G according to the Working Formulation) was diagnosed. Clinical pathological staging detected stage IE (extranodal) primary epididymal lymphoma. The patient was referred to the Hematologic Unit for combined chemotherapy, according to the VACOP-B protocol. After an 18-month follow-up the patient is well and disease free. CONCLUSIONS: When an epididymal mass does not benefit from medical treatment, scrotal exploration and fresh frozen sections of the lesion should be done. The possible bilateral involvement by primary epididymal lymphoma has to be kept in mind. Radical orchiectomy is the treatment of choice for primary lymphoma of the epididymis. Adjuvant chemotherapy is indicated in high-grade malignant lymphoma. Prognostic parameters of the disease may be the grade of malignancy and the size of the tumor.

Adult↗
PubMed2001

Prognostic value of renal cell carcinoma nuclear grading: multivariate analysis of 333 cases.

OBJECTIVE: To evaluate the independent predictive value of the nuclear grading system according to Fuhrman in relation to the disease-specific survival of patients with renal clear cell carcinoma. MATERIAL AND METHODS: 333 patients who underwent radical nephrectomy for renal clear cell carcinoma between 1983 and 1999 were evaluated. In all patients we retrospectively studied nuclear grading, average tumor size, multifocality, pathologic stage of primary tumor, vein invasion, lymph node involvement and distant metastases. The Kaplan-Meier method was applied to evaluate disease-specific survival rates. The log rank test was used to compare survival curves and for univariate analysis. The Cox proportional hazards model was used for the multivariate analysis. RESULTS: Histologic grade was G1 in 83 cases (25%), G2 in 117 cases (35%), G3 in 110 cases (33%) and G4 in 23 cases (7%). Our data showed that nuclear grading according to Fuhrman is related to medium tumor size (p < 0.0001), pathologic stage of cancer (p < 0.001), venous system invasion (p < 0.001), lymph node involvement (p < 0.001) and distant metastases (p < 0.001). The disease-specific survival after 5 and 10 years was 94 and 88%, respectively, in patients with G1, 86 and 75% in patients with G2, 59 and 40% in patients with G3 and 31% in patients with G4 (log rank p value < 0.0001). Multivariate analysis showed that nuclear grading by Fuhrman has a prognostic independent predictive value (hazard ratio = 1.8461, p = 0.002). CONCLUSIONS: Nuclear grading is an important independent predictive factor of disease-specific survival in patients with renal cell carcinoma.

Adult↗
PubMed2001

Renal vein and vena cava involvement does not affect prognosis in patients with renal cell carcinoma.

OBJECTIVES: The prognostic value of tumor extension into the renal vein or vena cava is still a controversial issue. The aim of this study is to report our experience with radical surgery in patients with renal cell carcinoma (RCC) extending into the renal vein or subdiaphragmatic vena cava. METHODS: We evaluated 142 patients with RCC involving the renal vein or inferior subdiaphragmatic vena cava. RCC had extended into the renal vein in 118 patients and into the inferior vena cava in the remaining 24. Radical nephrectomy was performed in all cases with renal vein invasion. Radical nephrectomy with cavotomy and tumor thrombus removal was carried out in all cases with inferior subdiaphragmatic vena caval invasion. Cause-specific survival was calculated by means of the Kaplan-Meier method. The log rank test was used for survival comparisons and univariate analysis. RESULTS: The 5- and 10-year cause-specific survival rates were 51.5 and 39%, respectively, in the group of patients with tumor extension into the renal vein and 33.4% in those with inferior vena caval involvement. In 52 patients (44%), RCC extended only into the renal vein. In the remaining 66 patients, renal vein invasion was associated with other adverse prognostic factors. Life expectancy was lower for patients with other concurrent adverse prognostic factors than for those affected by renal vein involvement alone (p < 0.0001). In the latter group, survival expectancy was similar to those with stage T2N0M0 tumor. In 7 cases (29%), inferior vena caval invasion was not associated with other adverse prognostic factors. In the remaining 15 patients (71%), vena caval involvement was associated with other adverse prognostic factors. Concurrence of other adverse prognostic factors with vena caval invasion significantly decreased the disease-specific survival expectancy in comparison with the patients in whom vena caval involvement was the main prognostic factor (p = 0.008). In these patients, disease-specific survival was similar to those with stage T2N0M0 tumor. CONCLUSION: Renal vein or inferior subdiaphragmatic vena caval involvement does not significantly affect prognosis in patients with RCC.

Adult↗
PubMed2001

Nephrogenic adenoma of the urinary bladder: our experience and review of the literature.

OBJECTIVE: To assess our experience in the treatment and clinical outcome of bladder nephrogenic adenoma (NA) updating and reviewing the literature concerning this issue. PATIENTS AND METHODS: From September 1976 to June 1999, bladder NA was diagnosed in 8 patients: 6 men and 2 women with a 3:1 male ratio, aged 26-80 (mean 58.3) years. Follow-up ranged from 4 to 194 (mean 93.5) months. RESULTS: NA was associated with transitional cell carcinoma in 3 cases. Predisposing factors were assessed in all patients. Previous surgery of the lower urinary tract was detected in 5 cases: ureterocystoneostomy in 2, partial cystectomy in 1, repair of vesicouterine fistula in 1, and multiple urethroplasties in 1. Previous endoscopic treatments were carried out in 2 patients, transurethral resection of the prostate in 1 and repeated transurethral resection of the vesicle in the other. A history of intravesical instillation of bacillus Calmette-Guérin was assessed in 1 case. Patients complained of irritative voiding symptoms in 6 cases and hematuria in 2. Endoscopically, the lesions appeared polypoid and multifocal in 5 patients, and flat and single in 3. The lesions were removed endoscopically, providing relief of symptoms in all cases. Histopathology assessed the diagnosis of nephrogenic adenoma, detecting focal atypic cells in 1 case only. Five patients (63%) relapsed 2-24 months after management. Recurrences were also treated endoscopically. CONCLUSIONS: Clinical and endoscopic features of bladder NA are not specific, simulating urothelial carcinoma or chronic cystitis. Endoscopic management allows accurate histological diagnosis and provides long-lasting relief of symptoms. NA needs careful and long-term follow-up, because of the high risk of recurrences and the potential neoplastic degeneration of the metaplastic urothelium.

Adenoma↗
PubMed2001

Tradeoffs in elastographic imaging.

This paper presents the tradeoffs in elastographic imaging. Elastography is viewed as a new imaging modality and presented in terms of three fundamental concepts that constitute the basis for the elastographic imaging process. These are the tissue elastic deformation process, the statistical analysis of strain estimation and the image characterization. The first concept involves the use of the contrast transfer efficiency (CTE) that describes the mapping of a distribution of local tissue elastic moduli into a distribution of local longitudinal tissue strains. The second concept defines the elastographic system and the relationship between ultrasonic and signal processing parameters. This process is described in terms of a stochastic framework (the strain filter) that provides upper and practical performance bounds and their dependence on the various system parameters. Finally, the output image, the elastogram, is characterized by its image parameters, such as signal-to-noise ratio, contrast-to-noise ratio, dynamic range and resolution. Finite-element simulations are used to generate examples of elastograms that are confirmed by the theoretical prediction tools.

Acoustics↗
PubMed2001

[Exogenous risk factors for parenchymal carcinoma of the kidney].

In the last decades incidence rates for renal cell carcinoma have been constantly increasing, especially in western European and Scandinavian countries and North America. Several epidemiological studies observed an increased relative risk of this tumour linked with some exogenous and/or environmental factors. The following exposures have been more consistently associated with renal cell carcinoma: tobacco smoking; occupational exposures (asbestos, aromatic hydrocarbons, chemical solvents); dietetic factors such as high energy intake, consumption of fried meats and poultry, and reduced intake of fruit and vegetables; iatrogenic factors such as analgesics and amphetamines; common diseases like obesity and hypertension. An effective preventive strategy for renal cancer could be carried out reducing the exposure to such risk factors.

Carcinoma, Renal Cell↗
PubMed2000

General state of health and psychological well-being in patients after surgery for urological malignant neoplasms.

OBJECTIVE: To evaluate the general state of health and the psychological well-being in a group of 155 patients after surgery for urological malignant neoplasms. MATERIALS AND METHODS: Surgery was performed in 55 patients for renal cell carcinoma, in 54 for invasive bladder carcinoma, in 30 for adenocarcinoma of the prostate, and in 16 for squamous penile carcinoma. All patients were invited to self-compile the General Health Questionnaire (GHQ) - 12 items according to Goldberg and the Hospital Anxiety and Depression Scale. Results were compared with those in a group of patients who underwent retropubic prostatectomy for benign prostatic hyperplasia. RESULTS AND CONCLUSION: The general state of health was significantly more impaired in neoplastic patients than in the control group. Levels of anxiety were significantly higher but depression levels were similar in both groups. As far as the type of tumor is concerned, patients who underwent radical cystectomy for bladder carcinoma and those treated with partial penectomy for squamous penile carcinoma showed a significant impairment of the general state of health compared with controls. Higher levels of anxiety were observed in patients who underwent ileal conduit after radical cystectomy, in those treated with radical prostatectomy for prostate cancer and in those who underwent partial penectomy. Significantly higher levels of depression than in the control group were observed only in patients with ileal conduit.

Adaptation, Psychological↗
PubMed2000

Modern imaging methods and preoperative management of pheochromocytoma: review of the literature and case report.

OBJECTIVES: To discuss the modern imaging techniques and preoperative management of pheochromocytoma and to report on one additional case. METHODS: A 66-year-old male with an incidentally discovered left adrenal mass is described. The adrenal medulla strongly accumulate 131 I-metaiodobenzylguanidine (MIBG). The patient underwent left adrenalectomy after preoperative therapy with alpha and beta-blockers. The recent literature on pheochromocytoma modern imaging techniques and preoperative management is reviewed. RESULTS: MIBG scintigraphy diagnosed a benign functioning adrenal pheochromocytoma, allowing preoperative medical management. Postoperative workup was unremarkable. Diagnosis of pheochromocytoma was confirmed by immunohistopathology. At 18 months follow-up, the patient is alive and disease-free. CONCLUSIONS: Incidentally discovered adrenal masses have to be investigated to detect malignancy and subtle hormonal overproduction. MIBG scintigraphy has a high specificity (100%) in detecting pheochromocytoma, metastasis, surgical residual tumor, local relapse and other adrenal crest tumors. Positive results of octreotide scintigraphy in detecting malignant pheochromocytoma have been reported. Currently, pheochromocytoma removal is a safe operation with mortality rates ranging from 0 to less than 3%. Preoperative alpha adrenergic blockage with phenoxybenzamine or prazosin is important in decreasing the operative risk. Beta-blockers may be necessary for cardiac arrhythmia. Intraoperative invasive monitoring of hemodynamic variables may be both diagnostic and therapeutic of inadequate preoperative management. Lifelong follow-up for patients with pheochromocytoma is important.

3-Iodobenzylguanidine↗
PubMed1999

The feasibility of elastographic visualization of HIFU-induced thermal lesions in soft tissues. Image-guided high-intensity focused ultrasound.

The potential for visualizing high-intensity focused ultrasound (HIFU)-induced thermal lesions in biological soft tissues in vitro using elastography was investigated. Thermal lesions were created in rabbit paraspinal skeletal muscle in vivo. The rabbits were sacrificed 60 h following the treatment and lesioned tissues were excised. The tissues were cast in a block of clear gel and elastographic images of the lesions were acquired. Gross pathology of the tissue samples confirmed the characteristics of the lesions.

Animals↗
PubMed1999

Elastographic characterization of HIFU-induced lesions in canine livers.

The elastographic visualization and evaluation of high-intensity focused ultrasound (HIFU)-induced lesions were investigated. The lesions were induced in vitro in freshly excised canine livers. The use of different treatment intensity levels and exposure times resulted in lesions of different sizes. Each lesion was clearly depicted by the corresponding elastogram as being an area harder than the background. The strain contrast of the lesion/background was found to be dependent on the level of energy deposition. A lesion/background strain contrast between -2.5 dB and -3.5 dB was found to completely define the entire zone of tissue damage. The area of tissue damage was automatically estimated from the elastograms by evaluating the number of pixels enclosed inside the isointensity contour lines corresponding to a strain contrast of -2.5, -3 and -3.5 dB. The area of the lesion was measured from a tissue photograph obtained at approximately the same plane where elastographic data were collected. The estimated lesion areas ranged between approximately 10 mm2 and 110 mm2. A high correlation between the damaged areas as depicted by the elastograms and the corresponding areas as measured from the gross pathology photographs was found (r2 = 0.93, p value < 0.0004, n = 16). This statistically significant high correlation demonstrates that elastography has the potential to become a reliable and accurate modality for HIFU therapy monitoring.

Animals↗
PubMed1998

[Primary dilated cardiomyopathy].

Recent advances in etiopathogenesis and natural history of idiopathic dilated cardiomyopathy are presented. The clinical and instrumental diagnosis and therapy are also reported.

Cardiomyopathy, Dilated↗