Biomedical subjects

R Nessi

Publications and source records attributed to R Nessi.

At least 19 recordsLinked to original sources

PubMed1998

[Computer-assisted image postprocessing in intraoral digital radiography].

INTRODUCTION: Computer-assisted postprocessing was performed on selected digital dental radiographs using a professional software for photographic retouching. MATERIALS AND METHODS: The optical characteristics of 22 digital intraoral images (radio-videographies) taken on 18 patients were modified as regards their density and contrast values. Three different kinds of densitometric curves, corresponding to particular changes in post-processing parameters, were preliminary defined as the most effective for the demonstration of root canals and of alveolar bone. They were then applied to each X-ray image and the pictures thus modified were subsequently printed and read on a blind basis by three observers who considered the conspicuity of each structure of interest (root canals and alveolar bone). RESULTS: The results, submitted to statistical analysis, demonstrate that computer-assisted postprocessing can improve the visual yield and the diagnostic effectiveness of digital dental images in 67% of cases for the periapical bone and in 86% of cases for the root canals. CONCLUSIONS: The most effective sets of post-processing parameters established for each structure of interest are proposed together with a pre-programmed function to be introduced into the software of digital radiographic equipments.

Adolescent↗

PubMed1996

[The measurement parameters in dental radiography: a comparison between traditional and digital technics].

Digital and conventional techniques for dental, panoramic and intraoral radiography, were compared to assess measurement accuracy. The study was carried out on two plastic models of maxillary and mandibular arches, each containing 14 teeth extracted and positioned in their anatomical site. The teeth were prepared by opening the pulpal cavity and inserting endodontic wires within the canals. Intraoral x-ray images were taken with long-cone technique using a commercial high-resolution film and with a charge coupled device (CCD) sensor (radiovisiography). The models were then submitted to panoramic tomography with photostimulable phosphor plates. The length of the canals was measured on each image and compared to the length of the inserted wires. For the digital pictures, the measurement was performed directly on the monitor with the aid of electronic calipers. Magnification averages 3.40%, 9.47% and 14.11% for anterior teeth in intraoral radiography, in radiovisiography and panoramic radiography, respectively. The results demonstrate the presence of some degree of magnification for every radiographic procedure. This effect becomes statistically significant for both radiovisiography and digital panoramic techniques, especially in the latter. In spite of their well-known practical and dosimetric advantages, digital techniques in dental radiology must be used carefully whenever a reliable measurement is required.

Analysis of Variance↗

PubMed1996

[Digital radiology in dentistry: experience with direct intraoral techniques (radiovideography)].

The aim of this paper was to discuss the techniques for intraoral digital radiography (radiovisiography) and to compare their accuracy in dental radiographical diagnosis. Emphasis was given to their potential applications in oral radiology. Radiovisiography was compared with intraoral films and electronic magnifications from digital panoramic radiographs in 38 patients, for a total amount of 36 caries, 27 periapical conditions and 58 metal implants. Moreover, the accuracy of the measurements made with the three techniques was assessed on a specimen of mandibular and maxillary arches containing 28 extracted teeth with endodontic files of known length. Radiovisiography was as effective as intraoral films and more effective than digital panoramic radiographs in the diagnosis of caries and periapical lesions. Nevertheless, it produced a significant magnification and yielded unreliable measurements of root canals and metal implants. Radiovisiography is very easy to use and does not require dark room procedures nor chemicals of any kind. In addition, it reduces patient's X-ray exposure by over 50% with respect to film studies. For these reasons, this technique seems to be worthy of widespread use in dental radiography, with the exception of the conditions requiring an exact measurement of working length.

Adult↗

PubMed1995

[A comparison between endoral radiography and electronic magnification of digital orthopantomography].

We compared the electronic magnifications obtained from digital panoramic radiographs with intraoral radiographs with a new high resolution film. Fifty-two patients were submitted to both examinations--76 comparative studies and 217 teeth studied in all. The two techniques appeared substantially comparable in terms of diagnostic effectiveness. The measurement of the alveolar ridge was strictly equivalent for the two examinations (< 1 mm disagreement in 80% of cases). The profile of lamina dura and the image of the radicular canal were better depicted with intraoral films. A useful advantage offered by digital images was the possibility of recognizing the soft tissues. In dental caries intraoral films was more effective than digital images and were correctly depicted small carious cavities (< 2 mm depth, 87 vs 74%). Digital panoramic radiography can be considered a promising alternative to panoramic film. Its electronic magnification may be a valuable diagnostic complement to intraoral films for the study of periodontal disease, but it cannot replace intraoral films for the assessment of fine dental details, small caries in particular. The new intraoral film was substantially equivalent to digital images for the assessment of bone lesions and of periodontal disease.

Adult↗

PubMed1995

[The spatial resolution of the digital storage phosphor system. The monitor and film compared].

The physical characteristics of radiographic images, namely spatial resolution and contrast, have obvious effects upon diagnostic image usefulness. We investigated the spatial resolution of both radiographs and magnified digital obtained with a storage phosphor system, in comparison with a film-screen combination. This study was carried out on the conventional radiographs of a phantom grid 0.5 mm thick, with resolution ranging from 0.5 to 10 lp/mm. Each examination was compared at naked eye and with the electronic evaluation of a region of interest on both standard and magnified views or by digitization with a charge coupled detector (CCD) television camera followed by the computing of the modulation transfer function curve. Our results demonstrate a higher spatial resolution of direct magnification, on both digital and film-screen pictures (over 5 lp/mm). On the contrary, the electronic magnification on the monitor yields the same spatial resolution as non-magnified digital images (up to 4.3 lp/mm). By selecting appropriate regions of interest, we could demonstrate the compression of the non-magnified images on the monitor. The modulation transfer curves show that direct magnification yields higher spatial resolution than electronic magnification and non-magnified views. Viewing electronically magnified images on the monitor yields the same resolution as contact radiographs: the monitor offers the advantage of an easier study of the regions of interest.

Evaluation Studies as Topic↗

PubMed1995

[Photo Compact Disc: proposal for the electronic storage of images].

We applied the Photo-CD technology to create an electronic image file easy and quick to use to optimize the retrieval of medical images for teaching purposes. We digitized 1,500 slides of diagnostic examinations from the archive of our Institution: the corresponding electronic files were stored on Photo-CD disks. The data relevant to every image were collected and recorded with the help of a relational data-base program. Thus, each user could retrieve the suitable images from the optical disks by a multiple and flexible key-word search. We compared the use of the electronic archive with a traditional hand-based file with the help of 3 teachers committed to prepare a lesson containing 5 slides on different subjects. The use of the electronic image archive corresponded to markedly shorter searching and file updating times. We tried also to assess the capabilites of this filing procedure for image post-processing and for the build-up of self-assessment programs.

CD-ROM↗

PubMed1995

[Dosimetric evaluations in dental radiology: comparison of the digital system and the conventional system].

The dosimetric values measured on digital dental examinations (panoramic radiography and cephalography) were compared with those obtained with screen-film combinations. The X-ray dose was measured at the critical organs (lens, thyroid, cervical cord) on an anthropomorphic phantom, using thermoluminescence dosimeters and an ionization chamber: the radiographic unit was set at the same exposure values used for standard human studies in adults and children. The mean thyroid dose for screen-film panoramic radiographs was 0.037 mGy in the child and 0.053 in the adult; the lens and the cord doses were 0.009-0.012 mGy and 0.096-0.135 mGy, respectively. Digital panoramic radiography gave the thyroid a dose of 0.013 mGy in the child and 0.016 mGy in the adult: such a marked dose reduction was observed for the lens and the cervical cord too (0.0044-0.0052 mGy and 0.035-0.042 mGy, respectively). With conventional film cephalography the thyroid was given a mean dose of 0.042-0.072 mGy according to age and to patient's size; the lens received higher doses (0.420-0.720 mGy). These values were markedly reduced with the digital technique; 0.032-0.034 mGy to the thyroid gland and 0.320-0.340 mGy to the lens; spinal cord doses became negligible with digital exposures (0.009-0.010 mGy). The overall analysis of dosimetric values demonstrated a mean dose reduction averaging 40-60% with respect to standard film exposure. This difference is more apparent in the adult, since the linear dose-response pattern of the digital system allows good images to be acquired in "thicker" people without markedly increasing exposure values.

Adult↗

PubMed1994

[Radiographic enlargement in the study of hand diseases. Digital versus conventional techniques].

The electronic magnification of digital images was compared with direct digital magnification and with plain radiograph magnification. A whole-body computed radiographic system with photostimulable phosphor plates contained inside standard X-ray cassettes was used. The small bones of the hands and wrists of 18 patients with traumatic (10 cases) or degenerative (8 cases) bone conditions mainly due to chronic renal failure were studied. Each patient was examined with all three techniques: the images were retrospectively reviewed by four observers relative to resolution, contrast, visibility of the lesions and diagnostic value of each method. The statistical analysis of our results demonstrated better yield of direct digital magnification than of plain radiograph (p = 0.00043) and of electronic (p = 7.5 10(-13) magnification. This finding was mainly due to density and contrast optimization of digital images, in spite of their low spatial resolution. This feature allows good simultaneous representation of structures with different radiographic densities, as it happens in the hand and wrist. Electronic magnification yielded less brilliant results, even if compared with plain radiographic studies (p = 0.0032). However, this limitation was compensated for by the fact that this technique is easier and quicker to perform and that it does not require any additional X-ray exposure.

Adult↗

PubMed1993

[Amyloid osteoarthropathy in dialyzed patients: integrated imaging].

We studied with US both the knees of 32 long-term dialysis patients (mean dialysis age: 69.7 months), 7 of whom exhibited palpable joint swelling. In 29/32 patients, US scans were combined with knee X-ray films, patellar views included. In one case, opaque arthrography was performed too. US demonstrated the presence of fluid collections within both joint space and synovial cavities in 19/32 patients (59%). Their content was transonic or mildly hypoechoic. X-ray films were positive for amyloid bone involvement in 19/29 cases (66%), with evidence of intra-osseous cysts and cortical erosions. There was a good general agreement between the results obtained with the two techniques: therefore, in some cases only one examination was positive. Needle aspiration of synovial fluid was performed in 18/32 patients (56%). The 2 cases of diffusely hypoechoic collections yielded very dense jelly material, that was highly positive for beta-2-microglobulin. US is proposed, combined with conventional X-ray films, as a simple and reliable method for the diagnosis of articular amyloidosis in dialysis patients and for the follow-up of this disease.

Amyloid↗

PubMed1993

[Digital cephalometric teleradiography with storage phosphors. Comparative study].

Digital cephalometric radiography with light-emitting phosphors was performed on 15 patients during an orthodontic survey. Lateral views were performed; digital post-processing was carried out according to 3 different sets of characteristic variables (analogic-like, Xeroradiography-like and custom-made). Comparative cephalometric film radiographs were performed on another group of 15 patients matched for age and clinical problems. All the digital and conventional images were evaluated by 3 independent observers, who scored 0-2 the visibility of 16 cephalometric landmarks. Digital cephalometric radiography always provided good and clear images, which were easy to read by every observer, thanks to contrast optimization in the digital technique and to the possibility of interactive post-processing that could improve the lowest-quality images. The visibility study of 16 cephalometric landmarks resulted in a moderately higher score for film cephalography than for the digital technique (79.6/96 versus 78.1/96). Among digital post-processing variables, the customized curve gave the best results (mean score: 78.8/96). Digital cephalometric radiography allowed marked reduction in radiation dose (approximately 30-40% of conventional radiographs). This is a major factor when considering the widespread use of this technique and the young age of most patients.

Cephalometry↗

PubMed1992

[The use of digital techniques with storage phosphors for orthopantomography. Preliminary note].

Digital panoramic tomographies with light-emitting phosphors were obtained in 39 patients, during a study on the clinical applications of digital imaging. Performing digital panoramic radiographies required the preliminary adaptation of the imaging plates to the cassette holder of the radiographic equipment. The digital images were post-processed according to two different protocols, both of which were recorded for each patient. The former image was quite similar to standard X-ray films and was called "analogic-like". The latter, called "xeroradiographic-like", featured a flattening of the overall contrast together with detail contrast enhancement due to the presence of an edge effect, as it occurs in xeroradiography. Digital panoramic tomography allows a marked reduction in patient's exposure to X-rays. In addition, this technique offers constant high-quality results, due to the possibility of recovering over- or under-exposed images during post-processing. Xeroradiographic-like digital films may reduce the sharp contrast that is often present between the anterior and the lateral portions of the maxillary and mandibular arches, thus improving the diagnostic reliability of the examination. Other modalities of digital post-processing may be helpful to depict gingival soft tissues, with obvious advantages for the study of periodontal diseases.

Adolescent↗

PubMed1991

Skin ultrasound in dermatologic surgical planning.

High-resolution ultrasonography was performed on 55 patients with palpable skin lesions, all submitted to surgical excision and to histologic diagnosis. In all the cases, the ultrasound picture was confirmed by the surgical appearance of the lesions. The sonographic structure was characteristic in the case of cysts and angiomas, lymphangiomas in particular. Ultrasonography is considered a simple and reliable technique for the pre-operative evaluation of skin nodules, as it gives a clear picture of their size, depth, and outline. However, sonography cannot substitute for the clinical dermatologic approach and the need for an histologic diagnosis.

Adult↗

PubMed1991

Bronchial carcinoid tumors: radiologic observations in 49 cases.

A retrospective evaluation was performed of radiographs obtained in 49 cases of bronchial carcinoid at presentation and during a follow-up period of 12 years. Histologic diagnosis from the surgical specimen was available in all cases. Carcinoids appeared most frequently (77%) as round or oval opacities with sharp and often notched margins. They often induced airway compression with pulmonary atelectasis; enlarged hilar lymph nodes from metastasis were rare. Recurrence after surgical removal was not frequent; the recurrent masses had the same radiographic features as the original tumor. The diagnosis of bronchial carcinoid must be taken into consideration when a slowly growing radiopaque mass with well-defined margins is discovered on chest films. The radiologist must remember that these tumors can be resected with a fairly good prognosis even when they are large.

Bronchial Neoplasms↗

PubMed1991

[Use of echography for the diagnosis of joint amyloidosis in dialyzed patients].

Amyloid arthropathy is an important complication of long-term hemodialysis. This condition may lead to destructive bone lesions and to severe functional impairment. We studied with sonography of both knees 32 long-term dialysis patients (mean dialytic age: 69.7 months), whose 7 were carrying palpable joint swellings. In 29/32 patients, ultrasound scans were associated with knee X-rays films, patellar views included. In one case, opaque arthrography was performed too. Sonography demonstrated the presence of fluid collections within the articular space and the synovial cavities in 19/32 patients (59%). Their content was transonic or mildly hypoechoic. X-ray films were positive for amyloid bone involvement in 19/29 cases (66%), with intra-osseous cysts and cortical erosions. There was a good general agreement between the results obtained with the two techniques: therefore, in some cases only one examination was positive. Sonography is proposed, in association with standard X-ray films, as a simple and reliable method for the diagnosis of articular amyloidosis in dialysis patients and for the follow-up of this disease.

Amyloidosis↗

PubMed1990

Ultrasonography of nodular and infiltrative lesions of the skin and subcutaneous tissues.

Ultrasonography with high-frequency probes was performed on 80 dermatological patients carrying palpable lesions of the skin. The case list included hemo- and lymphangiomas (16 cases), cysts (13 cases), Kaposi sarcomas (9 cases), and panniculitis (20 cases). All lesions underwent open biopsy and histological examination. Ultrasound yielded technically adequate images in 74/80 cases (93%). Angiomas appeared as multiple transonic cavities separated by hyperechoic septa; cysts were usually echo free or weakly echogenic, with smooth outlines. Kaposi sarcomas corresponded to superficial hypoechoic nodules with blurred margins, while panniculitis appeared as a diffuse thickening of the subcutaneous space. When acute inflammation was present, as in most cases of erythema nodosum, a nonhomogeneous hypoechoic pattern was found.

Cysts↗

PubMed1990

Ultrasound in degenerative cystic meniscal disease of the knee.

Ultrasonography of the knee joint using small-parts probes was performed on 27 patients with clinical findings suggestive of meniscal cystic degeneration. Surgical or arthroscopic confirmation of sonographic findings was obtained in all cases. Sonography delineated the shape and structure of the meniscal profile and any degenerative changes. In the initial stage (6/27 patients, 22%), minor structural irregularities could be observed. Small, round, transonic cysts were found in 8 patients (30%); these lay mainly within the meniscus and were movable during stress flexion of the leg. In more advanced cases (8/27, 30%), larger cysts sometimes protruded on the skin surface. In 3 patients (12%), the soft tissue swelling was associated with a normal sonographic aspect of the menisci, but sonography could demonstrate an effusion of extra-articular origin. Ultrasound is a simple and effective method for the assessment of degenerative cysts of the menisci. It allows a reliable differential diagnosis between meniscal cysts and other causes of soft tissue swelling, and it is well suited for monitoring the course of the disease.

Cartilage Diseases↗

PubMed1990

Ultrasonography of proliferative vascular lesions of the skin.

High-resolution ultrasonography with small part probes was performed on 20 proliferative vascular lesions of the skin (3 lymphangiomas, 9 hemangiomas, 8 Kaposi sarcomas). All the lesions were submitted to histological examination. The histological cuts were made in the same planes as the ultrasound scans in order to obtain a direct comparison. The sonographic pattern of each histotype is characteristic and correlated with the corresponding histological picture. Lymphangiomas appear as large anechoic communicating cavities; hemangiomas have small hypoechoic areas separated by thin hyperechoic septa. Kaposi sarcomas possess a mixed sonographic structure with ill-defined margins. Ultrasound is proposed as a simple and harmless diagnostic aid to clinical examination of proliferative vascular lesions of the skin.

Adult↗

PubMed1990

[Pure and diluted contrast media in the visualization of the portal venous system using digital angiography].

We report the results of intra-arterial digital subtraction angiography (DSA) in 100 patients with portal hypertension. The portal venous system was evaluated; all patients underwent angiography of the celiac and superior mesenteric arteries before surgery. Forty-four of them were also examined after Warren splenorenal shunts. Therefore, a total of 144 exams was evaluated. The authors always employed low-osmolality ionic and non-ionic contrast media (iodine concentration: 300-350 mg/ml). In 70 cases pure contrast medium was injected (20-25 ml); in the extant 74 cases it was diluted with an equal volume of saline solution (osmolality and iodine concentration reduced by 50%). Intra-arterial DSA always visualized portal venous system, collateral circulation, shunt location and postoperative changes. The major advantage of intra-arterial DSA is the smaller amount of contrast medium injected, so that local and systemic side effects are rare. According to our experience, it is best to dilute the contrast medium and inject the same amount as in conventional angiography, at the same rate. Other well-known advantages of intra-arterial DSA are quicker execution, less injury to arteries using smaller-caliber catheters, and low cost. The major disadvantage of intra-arterial DSA, as it appeared also in our study, is the field size of the intensifier, which in our case was limited to 6-9 inches. This is an insufficient coverage for the whole portal system to be studied, and some contrast medium injections become therefore necessary. An average of 3 injections were given to each patient. This problem reduces the advantage of less contrast medium per injection. At any rate, even though intra-arterial DSA exhibits this limitation, it can nevertheless yield important information in the pre- and postoperative evaluation of patients with portal hypertension.

Adult↗