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Biomedical subjects

G Simonetti

Publications and source records attributed to G Simonetti.

At least 127 records · Page 7Linked to original sources
PubMed1992

[The stenotic-occlusive anatomy and pathology of the renal arteries. Their evaluation by magnetic resonance angiography].

Magnetic resonance angiography of the renal arteries was performed in 10 healthy subjects, 10 patients with renal artery stenosis and 2 patients with accessory renal artery (1 unilateral, 1 bilateral). All patients selected among 35 subjects with suspected renovascular hypertension had previously undergone digital subtraction angiography. Four patients were studied before and after percutaneous transluminal angioplasty. MRA was performed with time-of-flight technique, with 2D and 3D FISP and 2D FLASH gradient-echo sequences. Digital subtraction angiography demonstrated stenoses ranging 40% to 90% in 10 cases, 7 unilateral (1 transplanted kidney) and 3 bilateral. RA correctly depicted > 90% stenoses in 5 cases, between 50% and 90% stenoses in 2 cases and < 50% in 2 cases. Four stenoses were not properly graded (3 over-graded and 1 not visualized because distal to ostium). Diagnostic accuracy was 71% for unilateral stenoses and 66% for bilateral stenoses (overall accuracy 69.2%).

Adult↗
PubMed1992

[Percutaneous transluminal renal angioplasty of the solitary kidney].

We report on our experience with percutaneous transluminal angioplasty (PTA) of the renal artery in solitary kidney patients. PTA was performed on 31 subjects (mean age: 52 years): 7 had a solitary kidney because of nephrectomy and 24 had a solitary functioning kidney. Patients were selected with clinical and laboratory examinations first and then with angiography. PTA was employed to treat renal artery stenoses 60%-95% of the whole arterial lumen. The procedure has been considered technically successful in 29 cases, with 77%-33% reduction of the mean amount of stenosis. As to the clinical evaluation of the results, blood pressure and creatinine values variations were considered. Of the 25 patients on follow-up, 13 appeared to be treated (52%), 8 improved (32%) and 4 unchanged (18%). On the whole, we observed 5 complications (2 hematomas at the approach site, 1 intimal dissection and 2 segmental infarcts), with a 23.4% rate comparable with PTA complications in non-solitary kidney patients. The good revascularization, the reduction in blood pressure values, the very small percentage of complications point to PTA of the renal artery as the procedure of choice in solitary kidney patients.

Adult↗
PubMed1992

[The use of the single-pulse RARE sequence in the study of the cerebrospinal axis].

The authors describe a fast MR sequence allowing to obtain a myelographic-like, markedly T2-weighted, image quite similar to conventional myelographies. Relative to conventional spin-echo sequences, in which echoes are encoded so as to achieve the same phase, each echo of the sequence here employed is given a different phase encoding. The sequence, called MYUR (myelography-urography) is based on the generation, after a 90 degrees pulse, of a "train" of 256 echoes, each one phase-encoded differently, by multiple 180 degrees pulses, producing a single image. The total duration of such a sequence, with 2 repetitions, is 21 seconds. The MR myelographic sequence allows to univocally study tissues with a very long T2 relaxation time; under normal conditions, only cerebrospinal fluid, urine and bile are demonstrated. A resistive MR unit operating at 0.28 T was employed in the present study. MR myelography is capable of pointing out an eventual dural sac compression or a space-occupying mass, thus allowing an effective scout-view to center the subsequent pulse sequences; all MR-myelographic exams need to be completed with other short and long TR sequences.

Brain↗
PubMed1992

[Vascular radiology and physics of fluids].

In the cardiovascular system, morphology and functionality are closely related. The observation that atherosclerotic lesions appear with different incidence in the various sites and prefer bifurcations, suggested that vascular architecture might be an important pathogenic factor. Vascular geometry deals with the evaluation of the "form" element from a theoretical point of a view, pointing out the angles and diameters which can make the arterial system physiologically more efficient. The key element of the system is the bifurcation: depending on whether bifurcations are considered as a single entity or as a whole, either "local" or "global" geometry is employed. The morphology of the bifurcation directly affects blood flow patterns, influencing both blood flow velocity and wall shear stress. Experimental studies evidenced that high blood flow velocities and low wall shear stress have, respectively, a preventive or favorable role in atheroma development. By observing these altered flow sites, the areas which are most likely to develop atherosclerotic damage have been detected in the various bifurcations; the areas correspond to angiographic and autoptic findings. Based on their experience, the authors discuss the contribution that the different imaging techniques can give to the study of vascular geometry.

Angiography↗
PubMed1992

[Oral contrast media in the study of the esophagus with magnetic resonance. Proposal of a new preparation].

The major problem in MRI of the esophagus is the lack of a reliable oral contrast agent. To determine the value of Gd-DTPA as an oral contrast medium for the esophagus as a part of phase III clinical trial, 17 patients (10 esophageal neoplasms, 4 neoplasms of the pharyngo-laryngeal tract, 3 Zenker's diverticula) underwent MRI. The oral contrast medium is proposed in a new preparation: 5 cc of oral Gd-DTPA were emulsionated with 30 g of a low-density barium paste for esophageal CT (3% p/v). High signal intensity in the esophageal lumen was observed in all patients and in all sequences. In neoplastic lesions, the c.m. improved the definition of both the level of stenosis and the longitudinal extent of the lesion. In diverticula, the real and the false lumen could be demonstrated. In one patient the exam could not be completed. No adverse reactions were observed.

Administration, Oral↗
PubMed1992

[Role of MR in characterizing expansive lesions of the adrenal gland].

Five patients with adrenal tumors (20 metastases, 12 adenomas, 8 myelolipomas, 6 primary tumors, 4 pheochromocytomas, and 1 hyperplasia) were studied by means of MRI with SE sequences. Twenty of them underwent dynamic study with GE sequences after i.v. injection of paramagnetic contrast media. Sixteen of 20 metastases exhibited low signal intensity on T1 and high signal on T2. One patient had low signal on both T1 and T2. Two lesions in patients with melanoma showed high signal in T1; in 1 case, the lesion exhibited a hemorrhagic area. Signal from adenomas was low in T1- and T2-weighted pulse sequences in 10/12 patients, while in the extant 2 cases signal was higher in T2. Myelolipomas had hyperintense signal on T1-weighted images in 5 cases and isointense signal with the renal cortex in the extant 3 cases. Pheochromocytomas and primary tumors appeared hypointense on T1 and hyperintense on T2. In 3 CT questionable cases, MRI showed the adrenal origin of the lesion. Dynamic study with GE sequences after Gd-DTPA injection showed low enhancement and fast washout in adenomas, while malignant lesions had higher enhancement and slower washout. In our study, MRI allowed to correctly characterize 11/12 adenomas, with only 1 false negative in a metastatic lesion.

Adrenal Gland Neoplasms↗
PubMed1992

[Magnetic resonance angiography in the study of abdominal neoplasms. Preliminary experience].

This study was designed to evaluate MRA imaging as a potential non-invasive method to study vascular infiltration in patients with abdominal neoplasms. Forty-three patients with abdominal tumors proven by CT and/or MRI were examined with MRA and subsequently with angiography. Of 15 cases of liver tumor, MRA allowed poor intratumoral vascularization to be demonstrated in 1 patient only, but it always provided a characteristic sign--i.e., the complete absence of flow in the hepatic segments infiltrated by the tumor and the evidence of pericapsular neovascularization. In 8 cases portal vein involvement was observed (4 cases of compression/dislocation, 2 cases of infiltration and 2 of thrombosis). In all cases MRA allowed the relationship between tumor and venous structures to be evaluated. It also demonstrated collateral vessel formations in 8 patients with cancrocirrhosis. Two cases of thrombosis and 3 infiltrations of the vena cava were demonstrated. Neither hepatic artery nor intrahepatic arterial vascularization could be correctly evaluated. Of 10 cases of renal tumors and in 3 of adrenal tumors, renal vein infiltration was seen in 4 cases and compression in 3, with only 1 false-positive finding. In these patients and in those with retroperitoneal masses, MRA provided valuable information on the relationship between tumor and vascular structures and was useful in detecting collateral vessels. In our experience, MRA is to be considered as a complementary technique to be performed after CT or MRI when additional information is needed as to the relationship between tumor and vascular structures. In the preoperative evaluation of abdominal neoplasm, angiography remains the gold standard, in spite of its invasiveness.

Abdominal Neoplasms↗
PubMed1992

[Preoperative staging and recurrence of rectal tumors. Comparison of transrectal ultrasonography and magnetic resonance].

The accuracy of transrectal US (TRUS) and of MRI was evaluated in the preoperative staging and in local recurrences of rectal cancers. Fifty-four patients were examined: 45, with known rectal cancer, for preoperative staging, and 9 for the evaluation of local recurrences. Nineteen patients were examined with MRI in basal conditions, 21 after rectal air enema and 5 after paramagnetic contrast enema (Gd-DTPA). The following parameters were evaluated for preoperative staging: wall infiltration, invasion of perirectal fat and adjacent structures, lymph node involvement. Morphologic and signal intensity (on MRI) changes were evaluated for the diagnosis of local recurrences. TRUS provided 2 false positives. In the same patients, basal MRI results were poor, owing to difficult demonstration of the different wall layers, while in the patients studied after air enema, the lesion was hyperintense. In 20 patients with a fat-infiltrating tumor, TRUS provided 3 false negatives and 2 false positives; basal MRI yielded poor results, while air enema and paramagnetic contrast enema clearly demonstrated all fat-infiltrating lesions, with only one false positive.

Air↗
PubMed1991

Phase I study of spiroplatin.

Spiroplatin was investigated in a multicentre phase I study. 67 patients with advanced solid tumours received 151 cycles either by short-term or prolonged infusion, repeated every 3 weeks, at 2.5-40 mg/m2. Myelosuppression and renal toxicity were dose-limiting. Proteinuria, which was dose- and schedule-dependent, indicated glomerular and tubular damage. The maximum tolerated doses (MTD) for poor-risk and good-risk patients were 35 and 40 mg/m2, respectively. The area under the curve (AUC) at the MTD did not correspond with the AUC at the LD10 in mice with ratios of 0.3 for free platinum and 2.6 for total platinum; these were not suitable for predicting the MTD. 1 complete response was observed in a patient with breast cancer and lung metastases and 1 partial response in a patient with adenocarcinoma of the lung. The recommended dose for phase II studies was 30 mg/m2 by 4 h infusion every 3 weeks.

Adult↗
PubMed1991

[Interventional radiology of the digestive system].

The authors report on the use of interventional radiology modalities in the treatment of some gastrointestinal diseases (intussusception, stenosis, hemorrhage, etc). The results are compared with literature data relative to both interventional radiology and conventional therapeutic procedures. In our series, hydrostatic reduction of ileocolic intussusception was successful in 60% of cases. Transluminal dilatation with a balloon catheter was attempted in 108 patients with alimentary tract stenosis and was successful in 93. Hemorrhage and ischemia can be treated by means of transcatheter therapy (vasopressin, embolization) and percutaneous angioplasty. Percutaneous gastrostomy appears to be an effective alternative to surgical gastrostomy. Tapeworm infections can be cured by intraduodenal injection of "Gastrografin" (Schering). The success achieved in the different applications is such as to suggest a wider use of interventional radiology procedures, for they offer a more favorable cost/benefit ratio and often yield better results than conventional techniques.

Digestive System↗
PubMed1991

[The radiological study of afferent and efferent loop syndromes].

The authors report on the diagnostic role of radiological imaging in the study of the patients who underwent gastric surgery. This kind of intervention is often followed by postoperative complications, so that accurate clinical-instrumental investigations are required. Routine controls both in the immediate postoperative period and during follow-up are useful especially when a neoplastic lesion was the underlying condition leading to surgery. Radiological imaging plays a fundamental role especially in evaluating such postoperative conditions as afferent and efferent loop syndromes. Radiology is thought to be essential to demonstrate the syndrome and to identify the mechanical/functional nature of the factors causing the disease, all of which are essential to an appropriate and safe therapy. Both the duration of follow-up (early and late controls) and the choice of contrast (water-soluble contrast medium or double contrast enema) are very important factors depending on the time of surgery and the clinical indication.

Afferent Loop Syndrome↗
PubMed1991

[The presurgical staging of soft-tissue sarcomas of the extremities: imaging diagnosis].

The authors studied 43 patients affected with soft tissue sarcomas to evaluate the accuracy of different imaging modalities in predicting resectability. Locations included lower (30) and upper (11) limbs, axillary (2) and gluteal (2) regions. MR imaging was performed on 37 patients, CT on 35 and US on 30. All patients were preliminarily subjected to conventional radiographic examination. MR imaging proved to be the most reliable modality because it allowed the lesion site to be correctly determined relative to both anatomical compartments and lesion spread; its relationships to joints and vascular structures were also depicted. Intravenous administration of Gd-DTPA (to 9 patients) allowed important information to be gained as to identifying and quantifying tumoral necrosis, and made it possible to discriminate tumoral component from perilesional edema. In our experience, CT was shown to overstage the T parameter--due to difficult distinction of edemigen component, even with a careful use of angio-CT. On the contrary, CT was the modality of choice in recognizing bone cortical infiltrations, even small ones, and in identifying pulmonary metastases. US played a role in the staging of these neoplasms thanks to its recognizing even small lesions and, in case of suspected vascular involvement, it allowed even small infiltrations of the vascular wall to be demonstrated.

Adolescent↗
PubMed1991

[Experience with more than 200 cases of breast biopsy after preoperative spatial localization without radiostereotaxic equipment].

The use of mammography as a screening examination has considerably increased our ability to detect non-palpable breast lesions less than 1 cm phi. A conclusive diagnosis frequently requires surgical biopsy. However, breast lesions can be localized prior to surgical biopsy by placing a wire in the lesion, with/without the use of stereotaxic equipment. Our method for lesion localization consisted in acquiring two orthogonal radiographs (cranio-caudal and latero-lateral) centered on the nipple. We used 20-21 G needles, 6-10 cm long, with curved-end wire. Mammographic findings possibly suggesting cancer were: microcalcifications, nodules, spiculated opacities, and architectural distortions. From January 1987 to January 1990, 223 patients were submitted to needle localization of breast lesions under mammographic guidance and without stereotaxic equipment. Sixty-seven cases (30%) were positive for malignancy, with a 2.3:1 benign/malignant ratio. Patients' age ranged 30-70 years, but most of them were 50-60 years old. No significant complications were observed: in one case only the hook wire broke, within breast parenchyma, which was at any rate resected together with the surgical specimen.

Adult↗
PubMed1990

Phase I study of Brequinar sodium (NSC 368390) in patients with solid malignancies.

Brequinar sodium (DUP 785, NSC 368390) is a novel quinoline-carboxylic acid derivative that has been selected for clinical evaluation because of its broad spectrum of antitumor activity in animal models and its novel chemical structure. This compound inhibits the mitochondrial enzyme dihydroorotate dehydrogenase (DHO-DH), which catalyzes the conversion of dihydroorotate to orotate, leading to a blockage in the pyrimidine de novo biosynthesis. A total of 43 patients received 110 courses of Brequinar sodium by short-term intravenous (i.v.) infusion, which was repeated every 3 weeks. Dose escalation was initially based on a modified Fibonacci scheme. After pharmacokinetic data from mice and man became available, a pharmacologically guided dose escalation was used; at toxic levels, dose escalation was applied on the basis of clinical judgement. The dose-limiting toxicities were myelosuppression, mucositis, skin rash, nausea and vomiting. The maximum tolerable doses for poor- and good-risk patients were 1,500 and 2,250 mg/m2, respectively. One mixed response was observed in a patient with papillary carcinoma of the thyroid. The recommended doses for phase II studies are 1,200 and 1,800 mg/m2 Brequinar sodium, given by a 1-h i.v. infusion every 3 weeks to poor- and good-risk patients, respectively.

Adult↗
PubMed1990

Phase I study of mitozolomide on a once daily for 5 days schedule.

In a phase I study mitozolomide was given on a once daily for 5 days schedule to 18 patients with a variety of malignancies. Non-hematological toxicity was negligible. Significant myelosuppression occurred at a total dose as low as 62.5 mg/m2 per course. In particular, thrombocytopenia, which was unpredictable, precluded dose increments beyond 15 mg/m2 per day (or a total of 75 mg/m2). Antitumor effects were not observed. The 5-day schedule of mitozolomide appears to have no advantage over administration once every 3-4 weeks, and may even be more dangerous than the latter schedule.

Adult↗
PubMed1990

A phase II trial of sequential MTx and 5-FU alternated with 4-epidoxorubicin and cisplatin in advanced gastric cancer.

Twenty-one patients with advanced gastric adenocarcinoma were treated with a combination chemotherapy schedule of sequential methotrexate and 5-fluorouracil alternated with 4-epidoxorubicin and cisplatin. This scheme was active, with 7 partial responses leading to a response rate of 33% (+/- 20%). In two cases the tumor became operable. No severe toxicity developed and the treatment was usually well tolerated.

Adolescent↗
PubMed1990

TWAR: a new chlamydial species?

In 1986 Grayston and coworkers termed TWAR (or Taiwan Acute Respiratory) a new strain of Chlamydia which has still not received an exact taxonomic classification. In fact, whereas initially the TWAR strain was classified as C. psittaci because of its oval-shaped, glycogen free, dense inclusions, recent studies on the immunological analysis, DNA analysis and ultrastructural morphology, would seem to indicate that TWAR is a new Chlamydial species, whose proposed name as C. pneumonia. TWAR is mainly responsible for respiratory syndrome varying in gravity from a slight form to pneumonia, and is liable to give rise to epidemic forms; in addition, more recently, certain Authors have postulated its involvement in the pathogenesis of ischemic cardiopathy.

Chlamydia↗