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R Pozzi Mucelli

Publications and source records attributed to R Pozzi Mucelli.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Turbo STIR sequence: optimization and comparison with conventional STIR sequence in bone diseases].

INTRODUCTION: The most common fat-suppressed sequence used to study skeletal conditions is the STIR sequence which has shown high sensitivity in the detection of skeletal lesions and whose main drawback is its long acquisition time. Currently, Turbo-STIR (T-STIR) sequences can shorten the acquisition time. The purpose of this study was therefore to compare the conventional STIR sequence with the new T-STIR sequence in the study of skeletal conditions to compare their diagnostic yield. MATERIAL AND METHODS: Twenty patients with different types of skeletal lesions were examined. MR examinations were performed with a Philips Gyroscan S15/ACS II unit (1.5 T). All the patients underwent a STIR sequence (TR/TE = 1500/20, TI = 180 ms, matrix = 204 x 256, NEX = 2, slice thickness = 5 mm, acquisition time = 9 min 24 s) and a T-STIR sequence (TR/TE = 1500/20, TI = 180 ms, matrix = 204 x 256, NEX = 2, slice thickness = 5 mm, TFL = 3, acquisition time = 3 min 33 s). The images were evaluated by measuring both quantitative parameters--percent contrast (%C), contrast to noise ratio (C/N), signal to noise ratio (S/N)--and qualitative parameters--lesion conspicuity, margins and extension, motion artifacts, image quality. RESULTS: The only statistically significant difference between the two sequences was image quality, which was superior in the conventional STIR sequence (p < .05). No statistically significant difference was demonstrated with the quantitative evaluation. DISCUSSION: In this study, T-STIR sequences were performed with low-high acquisition profile to acquire an actual echo time of 20 ms which permits to obtain optimal S/N with good spatial resolution. Therefore, T-STIR sequences with low-high acquisition profile provides better results than T-STIR sequences with linear acquisition profile which permits to obtain an actual echo time of 40 ms. CONCLUSION: This work shows that T-STIR sequences can replace conventional STIR sequences in the study of skeletal conditions reducing the acquisition time by 60%. This result can be obtained only by an accurate optimization of acquisition parameters.

Adolescent↗
PubMed1997

[A comparison between an ionic paramagnetic contrast agent (Gd-DTPA) and a nonionic one (Gd-DTPA-BMA) in functional kidney evaluation with magnetic resonance].

INTRODUCTION: The combination of TGE sequences with bolus injection of paramagnetic contrast agents permits to study renal function and perfusion. We studied renal function with both an ionic (Gd-DTPA) and a nonionic paramagnetic contrast agent (Gd-DTPA-BMA) to compare their kinetics in normal kidneys. MATERIAL AND METHODS: Twenty MR examinations were performed on 20 subjects with normal renal function. Ten subjects were examined after i.v. injection of Gd-DTPA and the other ten subjects after i.v. injection of Gd-DTPA-BMA. MR examinations were performed on a Philips ACS II unit (1.5 T). Two sequences were acquired in all cases; an SE coronal T1-weighted sequence (TR/TE = 600/19 ms) and a TGE coronal T1-weighted sequence (TR/TE = 12/5 ms, flip angle = 25 degrees) performed after bolus injection of the contrast agent at 0.1 mmol/kg. Signal intensity time curves were obtained in all the cases. The signal intensity of the cortex, corticomedullary junction, medulla and the pyelocaliceal system of each kidney was measured using a region of interest (ROI). Signal intensity curves were analyzed considering some quantitative parameters such as the area under the curve (AUC), the peak (P) and the time to peak (T-P). RESULTS: In the subjects with normal renal function, four phases were demonstrated after the i.v. injection of either Gd-DTPA or Gd-DTPA-BMA, namely the cortical phase, the cortico-medullary junction phase, the medullary phase and the pyelocaliceal system phase. No statistically significant differences between the two agents were demonstrated in signal intensity time curves and quantitative parameters. CONCLUSIONS: Gd-DTPA and Gd-DTPA-BMA showed the same efficacy in renal function studies.

Analysis of Variance↗
PubMed1997

[Virtual endoscopy with computed tomography of the anatomical structures of the middle ear].

INTRODUCTION: We applied the new technique of virtual endoscopy to the middle ear because this anatomical area is characterized by favorable contrast. MATERIALS AND METHODS: CT examinations of the petrous bone were obtained using 1.5 mm thick 1 coronal axis slices, with 1 mm or 1.5 mm table feed, 120 kV, 140-170 mA and 2 s scan time. The images were reconstructed with the high resolution algorithm for bony structures and a small field of view (9.6 cm), separately for the right and left petrous bone. The images were then transferred on a workstation and processed with the Navigator virtual endoscopic software (General Electric). A threshold value ranging -350 to -600 HU was applied. RESULTS: A series of images is acquired as the virtual endoscope moves from the external auditory canal to the middle ear cavity. Images of the anterior, medial, and posterior surfaces of the middle ear are presented. Different views of the ossicles are also presented. High quality images were always obtained for the middle ear structures, including the ossicles. CT endoscopy of the middle ear provides a new view of the anatomy of this complex area. It has some advantages and disadvantages; the former can be summarized as follows: -demonstration of areas which are difficult to show with endoscopy because of the presence of membrana tympani; -the virtual endoscope can be placed in several positions and therefore it can be inserted in all sites and tortuous places of anatomical cavity; -nice and effective demonstration of the ossicular chain including the stapes. The disadvantages are related to the fact that the endoscopic reconstruction (such as any other three-dimensional reconstruction) is a representation of surfaces where different densities are necessarily homogenized. CONCLUSIONS: CT virtual endoscopy of the middle ear can currently be considered a complementary technique to conventional CT because it permits better anatomical detailing of this complex region.

Ear, Middle↗
PubMed1996

Three-dimensional reconstructions of carotid bifurcation from CT images: evaluation of different rendering methods.

Three-dimensional computed tomographic angiography (3D-CTA) and digital subtraction angiography of the cervical carotid artery were performed bilaterally in 15 patients with suspected stenoses. A new semi-automatic segmentation and new rendering methods were used. The degree of stenosis of internal carotid arteries, as determined both by axial slices and 3D images (surface, integral, maximum-intensity-projection, and raysum-rendered images), was compared qualitatively and quantitatively to angiographic findings. In correlation to angiography, the accuracy in determining the stenosis classification of internal carotid arteries was of 97% for axial slices and 59-90% for 3D images, respectively. Raysum (pseudoradiograph) rendering was found to be the most reliable rendering method and gave the most similar results to angiography. The accuracy of all rendering methods was improved by applying calcification removing algorithm, with a statistically significant difference between surface rendering without plaque removal and raysum rendering using the removing algorithm.

Adult↗
PubMed1995

[Optimization of scanning and processing parameters for the three-dimensional reconstruction in computerized tomography of the facial bones].

The evolution of computer technology has significantly improved the performances of three-dimensional reconstructions from Computed Tomographic images. The authors discuss the examination technique and the modalities of three-dimensional reconstruction based upon a new advanced workstation. This unit is based on a Sun Sparkstation linked with the main computer of the CT scanner. The workstation is extremely fast, the processing time for a high resolution three-dimensional image of the maxillofacial region being about 3 minutes. The scanning parameters, image reconstruction and visualization were investigated on cases of maxillofacial (mainly posttraumatic) conditions. The most important scanning parameters are slice thickness, table incrementation, dose, scan plane. Slice thickness and table incrementation are the parameters bearing the greatest influence on the quality of the three-dimensional images. Dose is also important but bears no influence on image quality: therefore it can be kept as low as possible to reduce patient exposure. The scanning plane has some minor effect; coronal images have some advantages over axial images but in many cases only axial images can be acquired. The reconstruction parameters are the threshold and the matrix. The threshold may range 70 to 300 HU but in most cases ranges 120 to 200 HU. An advantage offered by this system is that it allows threshold values to be changed after the reconstruction has been completed, without performing a new reconstruction. The visualization parameters include four rendering methods, i.e. the surface mode, the integral mode, the maximum intensity projection and the ray sum. The surface mode is the one yielding the best results for bones while the others are used for the reconstruction of soft tissues and vessels. The workstation enables the three-dimensional images to be processed with shading parameters, and to be modified with cut planes, disarticulation methods and other interactive methods.

Bone Diseases↗
PubMed1995

[Tridimensional reconstructions of intra- and extracranial arteries using computerized tomography].

Three-dimensional Computed Tomographic Angiography (3D CTA) is a new imaging technique for vascular structures. This study was aimed at investigating the diagnostic role of 3D CTA in the intracranial and extracranial arteries. Fifteen patients with intracranial artery disease (thirteen with aneurysms and two with arteriovenous malformations) and fifteen patients with stenosis of the common, internal or external carotid arteries underwent 3D CTA. All patients had been examined with intraarterial angiography. The CT examinations were performed with dynamic scanning during intravenous contrast agent administration. Three-millimeter thick contiguous slices were obtained in the cervical region and 1.5-mm contiguous slices in the intracranial region. CT findings were processed to produce 3D views on an independent workstation. 3D CTA results were compared with those of intraarterial DSA in all cases. Agreement was found in 13 of 15 cases of intracranial vascular abnormalities, and in 26 of the 30 carotid arteries in classifying the severity of the stenosis. The 3D views, which exhibit an excellent image quality, seem to be comparable to angiography in the intracranial and extracranial arteries. The main advantages of this technique are: 1) its low invasivity since only an intravenous contrast agent injection is required; 2) its easy and fast acquisition (2-3 minutes are needed if a non-spiral CT unit is used and less than one minute with spiral CT); 3) good demonstration of the calcified plaques which can be also removed with the softwares available at the workstation, to show the overall vessel lumen; 4) thanks to its simplicity the examination can also be performed in emergency (i.e. in patients with subarachnoid hemorrhage, if plain CT is positive for subarachnoid bleeding). Its main limitations are: 1) the need of an adequate concentration of contrast agent in the vessels; 2) artifacts due to calcified and bone structures; 3) no information about vessel inflow; 4) limited discrimination between arteries and veins in some areas (cavernous sinus); 5) limited field of view compared to angiography.

Carotid Arteries↗
PubMed1995

[Comparative evaluation of ultrasonography, computerized tomography, angiography and lipiodol CT in defining extent of hepatocarcinoma. A multicenter study].

The authors report the results of a multicentric trial on hepatocellular carcinoma (HCC) patients, whose lesions were confirmed with biopsy or by high (> 400 ng/ml) alpha-fetoprotein levels. The series consisted of 149 patients examined in 8 different centers and submitted to ultrasonography (US), Computed Tomography (CT) before and after contrast agent administration, angiography and Lipiodol CT. According to lesion size and number, the patients were divided with each imaging modality into three groups: a) group 1: unifocal HCC < 5 cm diameter; b) group 2: multifocal HCC with 2-3 nodules and/or tumor mass < 80 ml; c) multifocal HCC with more than 3 nodules (with total tumor mass not exceeding 40% of liver volume) or with total tumor mass > 80 ml. In 77 patients all the examinations were available for comparison. US and CT diagnosed more patients as belonging to group 1 than angiography and Lipiodol CT, while more patients were classified as groups 2 and 3 with angiography and Lipiodol CT, meaning that US and CT may understage some HCC cases (about 15%) because they show a lower number of nodules. This observation was confirmed by the direct comparison between US and Lipiodol CT (in 114 patients), CT and Lipiodol CT (in 103 patients) and angiography and Lipiodol CT (in 116 patients). US and Lipiodol CT were in disagreement in 18 cases, CT and Lipiodol CT in 16 cases and angiography and Lipiodol CT in 13 cases. In most of these cases, Lipiodol CT showed more lesions than the other techniques. The size of the undetected lesions was small, ranging few mm to 2 cm in nearly all cases. To conclude, the results of this multicentric trial show that Lipiodol CT is a fundamental tool to evaluate HCC extent. In contrast, conventional CT appeared not to add any significant piece of information and can therefore be excluded from the diagnostic protocol of HCC.

Angiography↗
PubMed1994

Fibromuscular dysplasia. A case report with multivessel vascular involvement.

A case of multivessel fibromuscular dysplasia involving the cervico-cephalic arteries, the right renal artery and the iliac arteries is reported. It was associated with reversible bilateral internal carotid arteries and vertebral arteries dissection, left thalamic infarct, right hemorrhagic cerebellar infarct, renovascular hypertension and intermittent claudication of the right lower limb. This report indicates that fibromuscular dysplasia is a systemic angiopathy. Renovascular hypertension may foster the appearance of complication such as dissection of the arteries affected by fibromuscular dysplasia. In the case investigated the dissection of cervico-cephalic arteries was followed by spontaneous healing and a favourable neurological outcome whereas at the iliac arteries a rapid deterioration was observed.

Adult↗
PubMed1994

[Anatomic characteristics of pelvic fascia and ligaments in computerized tomography].

The pelvic fascia consists of two layers, the parietal and the visceral layers I whose appendages represented by various septa and ligaments subdivide the pelvis in intra- and extraperitoneal spaces. These structures are extremely thin but can be demonstrated thanks to the high-quality images obtained with the latest CT scanners and to the good natural contrast of pelvic fat. To assess the visibility of the anatomic features of these structures, 50 patients with no pelvic conditions which could affect the thickness of the pelvic fasciae and ligaments were examined with CT. The pelvic visceral fascia was clearly demonstrated in 60% of cases, the rectovesical and rectovaginal septa and the medial umbilical ligaments were demonstrated in 100% and 92% of cases, respectively. The umbilico-prevesical fascia and the lateral umbilical ligaments were poorly demonstrated. The depiction of these structures improves the knowledge of pelvic anatomy and yields major pieces of information to better understand several pelvic conditions.

Adult↗
PubMed1994

[Pelvic fascia, ligaments, and spaces in neoplastic disease in computerized tomography].

The fasciae and ligaments which are visible on CT images as extremely thin structures in normal conditions tend to appear thicker in such abnormal conditions as pelvic neoplasms and are therefore easily demonstrated on axial scans. To assess the CT patterns and the meaning of fascial thickening, the CT images of 40 patients with pelvic tumors (25 rectal, 7 uterine, 6 ovarian and 2 bladder lesions) were examined. Ten cases of peritoneal carcinomatosis with ascitis were also studied. The umbilico-prevesical fascia was demonstrated in 60% of cases, while the medial umbilical ligaments, the pelvic visceral fascia and the rectovesical and rectovaginal septa were detected in 90, 96 and 100% of cases, respectively. Fascial thickening is not a specific sign of neoplastic disease since it can be due to neoplastic infiltration or be the response to an irritative stimulus. Moreover, fascial thickening can be observed also in inflammatory conditions of the pelvis and following major traumas. Thickened fasciae and ligaments make the demonstration of paravesical, intra- and extraperitoneal spaces easier, which is useful to distinguish both etiology and site of pelvic fluid collections. All these pieces of information lead to better understanding pelvic abnormalities.

Adult↗
PubMed1994

[Magnetic resonance of the cartilages of the large joints].

MRI of the articular cartilage requires a careful technical approach since this structure is very thin, with a peculiar internal architecture between the supporting matrix and the cell component. On MR images the normal articular cartilage has a zonal appearance. To optimize the variables for best visualization of the internal architecture of the hyaline articular cartilage, an ex vivo and in vivo study was carried out. Accurate T1 and T2 relaxation times of the articular cartilage were obtained with a particular mixed sequence and then used to create isocontrast intensity graphs. The latter allowed, in all pulse sequences (SE and GRE), the best combination of TR, TE and FA to optimize signal differences between cartilage areas. A trilaminar pattern was demonstrated, with a superficial and a deep hypointense areas, in all sequences, together with an intermediate area which was moderately hyperintense on SE images and markedly hyperintense on GRE images. In the current literature, MRI appears to have been widely used to investigate hyaline cartilage conditions. In many series, the technique proved its efficacy in assessing both acute (traumatic cartilage fractures, osteochondritis dissecans, arthritis) and chronic (arthrosis, chondromalacia patellae, Hoffa's disease, synovial plica syndrome) conditions of the articular cartilage. T2-weighted sequences (both SE and GRE) are widely known as the most accurate in assessing cartilage conditions, which depends mainly on the arthrographic effect of synovial fluid on T2-weighted images. Of late, also MR arthrography, especially MR arthrography after the i.v. administration of Gadolinium, has emerged as an outstanding technique to investigate articular cartilage conditions. On the basis of MR arthrography findings, some authors suggested a classification of osteochondritis dissecans, arthrosis and chondromalacia patellae on MR images. MR stages seem to be closely correlated with the histologic classification suggested for these conditions.

Cartilage Diseases↗
PubMed1994

[Thin-section computerized tomography of the kidney in the differential diagnosis of small tumor and cystic hypodensities].

Small hypodense renal lesions with a round shape are frequently detected on CT scans of the upper abdomen after contrast medium administration. In nearly all cases these round hypodensities are simple small cysts with no clinical significance. However, the fluid density of these cysts cannot be always defined, due to the partial volume averaging which occurs on CT when 10-mm-thick slices and contrast enhancement are used. Therefore, a malignant tumor--i.e., small renal tumors or metastatic lesions--cannot be ruled out in some cases. Since the limitations of CT are related to partial volume averaging, the authors used both 5-mm and 10-mm slices to reduce this artifact. Forty-eight small hypodensities (< 15 mm) were studied after contrast agent administration: 42 of them were simple cysts and 5 were tumoral lesions--i.e., 3 renal cell carcinomas and 2 lymphomatous lesions. The results showed that, with 5-mm slices, the density of the fluid hypodensities decreased in nearly all cases and in 81.3% of cases it was below 30 HU. The difference in densities between 10-mm and 5-mm slices was about 50 HU (75 +/- 30 to 21 +/- 16 HU). In the 5 tumoral hypodensities, lesion density was still in the soft tissue range also with 5-mm slices, with no major decrease. These results show that this technique is simple and effective in the differential diagnosis of small renal hypodensities since it requires only a short additional examination time.

Adult↗
PubMed1993

[Arterial anatomy of the celiac trunk and the superior mesenteric artery with computerized tomography].

A hundred patients with different conditions underwent CT and the results were retrospectively reviewed to evaluate the visibility of the celiac trunk, of its branches and of the superior mesenteric artery. Thirty-six patients underwent angiography too, which allowed the anatomical variants suspected on CT to be demonstrated, according to Kuhns' criteria. The other 64 patients were consecutively selected and only aneurysmal changes were not included. All examinations were performed using a General Electric 9800 Advantage scanner, with 2 second scanning time and 10 mm-thick contiguous scans. In 20 patients 5 mm contiguous scans were performed. All examinations followed i.v. injections of contrast agents which were given with an automatic injector. The cases with suspected anatomical variants on CT but with no angiographic confirmation were not considered. A hundred CT exams were retrospectively reviewed: the celiac trunk and the common hepatic artery were demonstrated in all of them. Visibility of the other branches was 40% for the hepatic artery, 53% for the right branch of the hepatic artery and 39% for its left branch, 70% for the gastroduodenal artery, 82% for the left gastric artery, 97% for the splenic artery and 100% for the superior mesenteric artery. As for the 36 patients who underwent both CT and angiography, right hepatic artery from the superior mesenteric artery was seen in 19% of cases with both modalities; common hepatic artery arising from the superior mesenteric artery was detected in 2% of cases. In both instances, these anatomical variants appeared as a vessel running posterior to the portal vein. The careful investigation of axial CT scans showed the level of origin of the artery from the superior mesenteric artery. These results are in agreement with the angiographic data reported in the literature. Our study demonstrated that the celiac trunk and its variants are always depicted by the new CT scanner. The knowledge of these variants may be useful in the patients to submit to liver surgery. The celiac trunk and its variants are demonstrated with conventional 10 mm slices. The use of 5 mm slices improves the visibility of thin anatomical branches but is not essential to recognize the major vessels and anatomical variants.

Celiac Artery↗
PubMed1993

[Comparative evaluation of the SPIR sequence with gadolinium and other sequences in bone diseases].

In order to assess the value of the SPIR (Spectral Presaturation with Inversion Recovery) sequence (a fat-suppression technique) with Gd-DTPA in the investigation of skeletal diseases, 50 patients were examined with conventional SE T1- and T2-weighted sequences, as well as with SE T1 and SPIR sequences after the i.v. injection of Gd-DTPA. Twenty patients were affected with a skeletal infection (11 spondylodiscites and 9 osteomyelitis) and 5 with a primary tumor; 15 had metastases and 10 a hemolymphopoietic disorder (6 myelomas and 4 non-Hodgkin's lymphomas). In the four groups of patients, the mean visibility of skeletal lesions was higher on SPIR images with Gd-DTPA than on the other images, even though a statistically significant difference was observed only in the group of infections (p < 0.002) and in myelomas and lymphomas (p < 0.001). In 13 cases with extraosseous spread, visibility was higher on contrast-SPIR images than on the other sequences, even though high sensitivity was also exhibited by SE T2-weighted sequences. Even though the SPIR sequence still exhibits some technical limitations, our study assesses the value of this sequences with Gd-DTPA in the investigation of skeletal lesions. The major advantages of contrast-SPIR imaging follow: 1) it shows skeletal lesions, which are isointense on enhanced SE T1-weighted images, 2) it provides better visibility of the lesion than the other sequences, more accurately defining their borders, 3) it provides better anatomical detailing than SE T2-weighted images and 4) its sensitivity is higher.

Adult↗
PubMed1992

[The anatomical assessment of the renal fascia in the normal subject by using computed tomographic equipment with advanced technology].

One hundred patients, affected with diseases not involving the peri-renal and pararenal spaces, have been examined in order to evaluate the visibility of the renal fasciae, using a CT scanner provided with high spatial and contrast resolution. The anterior renal fascia has been recognized in 71% of cases on the right side and in 88% on the left. The posterior renal fascia had 96% of positive bilateral detectability. The latero-conal fascia was detected in 83% of cases on the right and in 91% on the left. The inter-renal fascia was recognized in 25% of cases, at the pancreas or, more frequently, on caudal planes. The peri-renal septa were seen in 58% of cases, mainly on the left side. Compared to previous data reported by other authors, the visibility of the renal fasciae has been increased by the greater spatial and contrast resolution offered by the new CT scanner, thus allowing better anatomical evaluation of peri and para-renal spaces.

Adult↗
PubMed1988

[Evaluation of expansive myelo-vertebral pathology using different radiologic modalities, magnetic resonance excluded].

The authors review their personal experience in tumors of the spine and the spinal cord, based on 30 cases evaluated with plain x-ray film of the spine, plain Computed Tomography (CT), myelography and myelo-CT. The value of both plain film of the spine and CT in tumoral lesions involving the skeleton is assessed; however, as far as nervous structures are concerned myelography and myelo-CT are necessary. Both myelography and myelo-CT showed high sensitivity (96%), thus allowing the definition of intra- extra-thecal extension of the tumor, and its relationships with the spinal cord and surrounding structures. Myelo-CT turned out to be extremely useful in myelographic stop: the upper extension of the lesion could be defined in 85% of cases. However, the contribution of myelography and myelo-CT was relatively limited when positive findings were present at CT. The evaluation of the density of the lesions proved to be of limited value since no significant differences could be recognized in different tumors. Finally, a diagnostic protocol is proposed for patients with spinal neurologic symptoms, based upon the clinical level of the lesion.

Adult↗
PubMed1985

[Computed tomography of the femur head. Normal aspects and appearance in aseptic necrosis].

The diagnostic value of Computed Tomography (CT) in the diagnosis of the aseptic necrosis of the femoral head is discussed. The CT findings in the different evolutive stages are reported and the respective diagnostic value of Conventional Radiology and CT are discussed. The CT findings of femoral head necrosis in the early phases are emphasized. The capability of CT to demonstrate structural changes in femoral heads with regular morphology allows to consider this technique when there exists a clinical doubt of osteonecrosis of the femoral head and in risk patients.

Adult↗