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S Pani

Publications and source records attributed to S Pani.

At least 19 recordsLinked to original sources
PubMed2005

High resolution Ca/P maps of bone architecture in 3D synchrotron radiation microtomographic images.

The Ca/P ratio was measured in cortical bone samples from the femoral neck and tibia of different animal species, using synchrotron radiation microtomography. Use of a monoenergetic X-ray beam, as provided by the synchrotron facility, generates accurate 3D maps of the linear attenuation coefficient within the sample and hence gives the ability to map different chemical components. Also, by comparing normal and abnormal bones, i.e. osteoporotic (induced by inflammation), changes in the Ca/P ratio brought about by bone diseases can be detected. MicroCT data sets were collected at 20 and 28 keV for each bone sample and two calibration phantoms. From the 3D data sets, multiple 2D slices were reconstructed with a slice thickness of approximately 30 microm. Regions of interest were defined around suitable sites and were converted to Ca/P ratios using the data collected from the test phantoms. A significant difference (p<0.001) between osteoporotics and age-matched normals at both energies was detected. Differences between different bone sites from the same animal are not significant (p>0.5) while those between the same bone sites from different animals are highly significant (p<0.001). Differences between estimates made at 20 and 28 keV are not significant (p>0.5). An important aspect is the ability to map the spatial distribution of the Ca/P ratio.

Animals↗
PubMed2005

The effects of the imaging system on the validity limits of the ray-optical approach to phase contrast imaging.

A theoretical analysis of the x-ray phase contrast imaging and its validation via synchrotron radiation imaging is here presented. Two different mathematical models have been followed: the simpler ray-optical approach and the more rigorous Fresnel-Kirchoff diffraction theory. Subsequently, the conditions upon which the x-ray optical approximation can be used to describe the image formation mechanism have been analyzed, taking into account also the effects due to the finite source size and detector resolution. It is possible to demonstrate that the ray-optics results can also be obtained by opportunely developing the diffraction formalism only with some restrictions on the spatial frequencies present in the final image, without any limitation on the maximum phase shift. The conditions allowing the use of the simplified ray-optical approach to describe the phase contrast images have been here defined and their validation has been proved by means of computer simulations and phantom experiments.

Biophysical Phenomena↗
PubMed2002

Signal-to-noise ratio evaluation in dual-energy radiography with synchrotron radiation.

Dual-energy radiography is an effective technique that allows removal of contrast between pairs of materials in order to display details of interest on a uniform background. In mammographic images the detection of small nodules is often impeded by obscuring background 'clutter' resulting from the contrast between normal tissues (glandular and adipose) in their neighbourhood. We consider whether it could be possible to apply dual-energy radiography to the breast, which is hypothetically principally composed of three tissues, glandular, adipose and cancerous, in order to remove the contrast due to the distribution of normal tissues and, as a consequence, to enhance the intrinsic contrast of the pathology. The purpose of this work is to test the limitations of dual-energy radiography on a three-component phantom under optimum conditions of the source and detector. We use a synchrotron monochromatic beam, produced at the ELETTRA synchrotron facility (Trieste, Italy), and an imaging plate detector, in order to acquire two images at low and high energies of a phantom composed of polyethylene, plexiglas and water. For evaluation of the potential of this procedure we studied the signal-to-noise ratio (SNR) of polyethylene and water on a set of images obtained by applying the dual-energy procedure. We found that the SNR of polyethylene and water is around the detectability threshold (according to Rose's criteria) at the contrast cancellation angles. Finally we evaluated the air entrance dose required for this double exposure, resulting in 0.81 mGy for the low-energy image and 0.01 mGy for the high-energy image. To obtain the same image quality for a standard breast of 5.5 cm, mean glandular doses of 3.50 mGy and 0.03 mGy at 17 keV and at 34 keV, respectively, are required.

Algorithms↗
PubMed2002

Preliminary study on extremely small angle x-ray scatter imaging with synchrotron radiation.

Among the medical physics community, there is nowadays a great interest in the possible implementation of scatter imaging techniques, especially in the field of breast imaging. It is well known that malignant lesions and normal tissue differ in their scattering signatures, and thus scattered radiation can provide a powerful tool to distinguish between the two cases. Up to now, most of the proposed techniques rely on the detection of radiation scattered at angles of the order of a few degrees, which in most cases results in very high contrast values. On the other hand, at those relatively large angles the scattered flux is relatively low with respect to the primary, which often implies the necessity of increasing the dose delivered to the sample in order to achieve sufficient statistics. Furthermore, most of these techniques are based on pencil beam set-ups, which results in an increase of the overall duration of the examination. We propose here an alternative approach based on the detection of radiation scattered at extremely small angles, of the order of approximately 100-200 microrad. This results in a relatively high scattered flux (5-10% of the primary) and in the possibility of utilizing a fan beam geometry, which reduces the acquisition times with respect to pencil beam set-ups. Images of several samples have been acquired, demonstrating that the proposed technique results in an increased contrast with respect to absorption imaging. Possible in vivo implementations of the technique at no dose expense are finally discussed.

Algorithms↗
PubMed2001

An innovative digital imaging set-up allowing a low-dose approach to phase contrast applications in the medical field.

Recently, new imaging modalities based on the detection of weak phase perturbations effects, among which are phase contrast and diffraction imaging, have been developed by several researchers. Due to their high sensitivity to weakly absorbing details, these techniques seem to be very promising for applications in the medical field. On the other hand, digital radiology is undergoing a wide diffusion, and its benefits are presently very well understood. Up to now, however, the strong pixel size constraints associated with phase contrast pattern detection limited the possibility of exploiting the advantages of phase contrast in digital radiology applications. In this paper, an innovative setup capable of removing the pixel size constraints, and thus opening the way to low dose digital phase contrast imaging, is described. Furthermore, we introduce an imaging technique based on the detection of radiation scattered at small angles: the information extracted from the sample is increased at no dose expense. We believe that several radiological fields, mammography being the first important example, may benefit from the herein described innovative imaging techniques.

Diagnostic Imaging↗
PubMed2000

Experimental evaluation of a simple algorithm to enhance the spatial resolution in scanned radiographic systems.

In order to ensure an early diagnosis of breast cancer, an imaging system must fulfil extremely stringent requirements in terms of dynamic range, contrast resolution and spatial resolution. Furthermore, in order to reduce the dose delivered to the patient, a high efficiency of the detector device should be provided. In this paper the SYRMEP/FRONTRAD (SYnchrotron Radiation for MEdical Physics/FRONTier RADiology) mammography project, based on synchroton radiation and a novel solid state pixel detector, is briefly described. Particular relevance is given to the fact that the radiographic image is obtained by means of a scanning technique, which allows the possibility of utilizing a scanning step smaller than the pixel size. With this procedure, a convolution between the real image and the detector point spread function (PSF) is actually acquired: by carefully measuring the detector PSF, it is possible to apply a post-processing procedure (filtered deconvolution), which reconstructs images with enhanced spatial resolution. The image acquisition modality and the deconvolution algorithm are herein described, and some test object images, with spatial resolution enhanced by means of the filtered deconvolution procedure, are presented. As discussed in detail in this paper, this procedure allows us to obtain a spatial resolution determined by the scanning step, rather than by the pixel size.

Algorithms↗
PubMed2000

Mammography with synchrotron radiation: phase-detection techniques.

The authors evaluated the effect on mammographic examinations of the use of synchrotron radiation to detect phase-perturbation effects, which are higher than absorption effects for soft tissue in the energy range of 15-25 keV. Detection of phase-perturbation effects was possible because of the high degree of coherence of synchrotron radiation sources. Synchrotron radiation images were obtained of a mammographic phantom and in vitro breast tissue specimens and compared with conventional mammographic studies. On the basis of grades assigned by three reviewers, image quality of the former was considerably higher, and the delivered dose was fully compatible.

Absorption↗
PubMed1999

Bacteriological studies of blood, tissue fluid, lymph and lymph nodes in patients with acute dermatolymphangioadenitis (DLA) in course of 'filarial' lymphedema.

Filarial lymphedema is complicated by frequent episodes of dermatolymphangioadenitis (DLA). Severe systemic symptoms during attacks of DLA resemble those of septicemia. The question we asked was whether bacterial isolates can be found in the peripheral blood of patients during the episodes of DLA. Out of 100 patients referred to us with 'filarial' lymphedema 14 displayed acute and five subacute symptoms of DLA. All were on admission blood microfilariae negative but had a positive test in the past. Blood bacterial isolates were found in nine cases, four acute (21%) and five subacute (26%). In 10 acute cases blood cultures were found negative. Six blood isolates belonged to Bacilli, four to Cocci and one was Sarcina. To identify the sites of origin of bacterial dissemination, swabs taken from the calf skin biopsy wounds and tissue fluid, lymph and lymph node specimens were cultured. Swabs from the calf skin biopsy wound contained isolates in nine (47%) cases. They were Bacilli in nine, Cocci in three, Acinetobacter and Erwinia in two cases. Tissue fluid was collected from 10 patients and contained Bacilli in four (40%) and Staphylococci in three (30%). Lymph was drained in four patients and contained isolates in all samples (100%). They were Staphylococcus epidermis, xylosus and aureus, Acinetobacter, Bacillus subtilis and Sarcina. Three lymph nodes were biopsied and contained Staphylococcus chromogenes, xylosus, Enterococcus and Bacillus cereus. In six cases the same phenotypically defined species of bacteria were found in blood and limb tissues or fluids. In the 'control' group of patients with lymphedema without acute or subacute changes all blood cultures were negative. Interestingly, swabs from biopsy wound of these patients contained isolates in 80%, tissue fluid in 68%, lymph in 70% and lymph nodes in 58% of cases. In healthy controls, tissue fluid did not contain bacteria, and lymph isolates were found only in 12% of cases. This study demonstrates that patients with acute episodes of DLA reveal bacteremia in a high percentage of cases. Diversity of blood and tissue bacterial isolates in these patients points to a breakdown of the skin immune barrier in lymphedema and subsequently indiscriminate bacterial colonization of deep tissues and spread to an blood circulation.

Adolescent↗
PubMed1998

Low-dose phase contrast x-ray medical imaging.

Phase contrast x-ray imaging is a powerful technique for the detection of low-contrast details in weakly absorbing objects. This method is of possible relevance in the field of diagnostic radiology. In fact, imaging low-contrast details within soft tissue does not give satisfactory results in conventional x-ray absorption radiology, mammography being a typical example. Nevertheless, up to now all applications of the phase contrast technique, carried out on thin samples, have required radiation doses substantially higher than those delivered in conventional radiological examinations. To demonstrate the applicability of the method to mammography we produced phase contrast images of objects a few centimetres thick while delivering radiation doses lower than or comparable to doses needed in standard mammographic examinations (typically approximately 1 mGy mean glandular dose (MGD)). We show images of a custom mammographic phantom and of two specimens of human breast tissue obtained at the SYRMEP bending magnet beamline at Elettra, the Trieste synchrotron radiation facility. The introduction of an intensifier screen enabled us to obtain phase contrast images of these thick samples with radiation doses comparable to those used in mammography. Low absorbing details such as 50 microm thick nylon wires or thin calcium deposits (approximately 50 microm) within breast tissue, invisible with conventional techniques, are detected by means of the proposed method. We also find that the use of a bending magnet radiation source relaxes the previously reported requirements on source size for phase contrast imaging. Finally, the consistency of the results has been checked by theoretical simulations carried out for the purposes of this experiment.

Biopsy↗
PubMed1998

Mammography of a phantom and breast tissue with synchrotron radiation and a linear-array silicon detector.

A linear-array, silicon pixel detector, capable of counting single photons, was applied to mammography by using a synchrotron radiation beam. Images were obtained of both a mammographic phantom and a breast-tissue sample. The phantom image was acquired with a mean glandular dose of 0.32 mGy. This detector combined with a synchrotron radiation beam allows acquisition of high-contrast, low-dose images of soft tissues.

Breast↗
PubMed1997

A linear array silicon pixel detector: images of a mammographic test object and evaluation of delivered doses.

We present images of a mammographic test object obtained using a linear array silicon pixel detector capable of single-photon counting. The detector pixel size was 200 x 300 microns2 and images were acquired by scanning the test object between the laminar detector and the x-ray source with a scanning step of 100 microns. A molybdenum anode tube was used with two different filtrations: 2 mm aluminium and 25 microns molybdenum. Conventional film-screen images were also obtained in order to compare spatial and contrast resolution. In our digital images it is possible to recognize low-contrast details having dimensions smaller than or equal to the dimensions of details visible by means of a clinical mammographic unit. The detection of microcalcifications smaller than 150 microns was possible only when using the Mo filtration. However a copper wire of 50 microns diameter was detectable when embedded in a simulated tissue. We discuss in detail the mean glandular doses (MGDs) delivered during the image acquisition. The MGDs necessary to obtain good-quality images are always smaller than at a conventional mammographic unit. Since MGDs depend on the x-ray spectrum, the dose reduction becomes larger when the applied spectrum is harder than in film-screen acquisition (Al filtration and 35 kVp).

Female↗
PubMed1997

Bacteriologic studies of skin, tissue fluid, lymph, and lymph nodes in patients with filarial lymphedema.

Filarial lymphedema is complicated by frequent episodes of dermatolymphangioadenitis (DLA). It is not certain whether DLA is of filarial or bacterial etiology. The frequency of episodic DLA does not depend on the presence or absence of microfilariae. Antibiotic therapy is effective in prevention and treatment of DLA. These observations point to the bacterial rather than filarial etiology of DLA. Skin and lymph node biopsies, tissue fluid, lymph, and blood from patients with chronic filarial lymphedema, and during acute episodes of DLA, were cultured for detection of bacteria. A high prevalence of bacterial isolates from the tissue fluid (64%), lymph (75%), and inguinal lymph nodes (66%) of limbs with filarial lymphedema was found. Bacillus cereus, Staphylococcus epidermidis, S. hominis, S. capitis, S. xylosus, and Micrococcus spp. were the most common isolates. Bacteria were also isolated from the blood of patients with recent episodes of DLA, with strains of the same phenotype and antibiotic sensitivity in all specimens from patients with DLA. Bacterial strains of the same phenotype and antibiotic sensitivity were documented on the toe web surface and in tissue fluid (25%), lymph (26%), or lymph nodes (41%). Increasing prevalence of bacterial isolates in tissue fluid, lymph, and lymph nodes was observed in advanced stages of lymphedema. Bacilli and cocci were sensitive to gentamicin, tetracyline, rifampicin, vancomycin, kanamycin and cotrimoxazole, and least sensitive to penicillin. Blood cultures of patients in the periods between DLA attacks were negative. In healthy controls without edema and episodes of DLA, tissue fluid did not contain bacteria. In lymph, only single colonies of Micrococcus and Acinetobacter were cultured in 12% of the cases. Impaired lymph drainage and lack of elimination of penetrating bacteria may be responsible for progression of lymphedema and recurrent attacks of DLA.

Adolescent↗
PubMed1995

Primary lingual tuberculosis caused by M. bovis infection.

Although tuberculosis of tongue has been previously reported, its infrequent clinical presentation and increased chance of being overlooked during routine examination of the oral cavity, make it worthy of documentation. Lingual tuberculosis is usually associated with tuberculosis of the oropharynx, lungs, lymph nodes, and miliary tuberculosis. Primary tuberculosis of the tongue is extremely rare and is seldom reported. Early diagnosis of tuberculosis elsewhere in body and its effective treatment by antituberculous drugs may be the reason for its uncommon presentation. The relationship between consumption of raw or unboiled milk and tuberculosis of the tongue is ill-understood and has evidently not been reported. We take this opportunity to present the first case of primary lingual tuberculosis caused by Mycobacterium bovis related to consumption of unboiled cow milk.

Adult↗
PubMed1994

Turpentine poisoning: a case report.

The use of turpentine oil for suicidal and homicidal purposes has become quite infrequent with the increased availability of pesticides and toxic substances. Available literature exhibits few case reports of turpentine poisoning. Such a case is reported here which presented as status epilepticus, unresponsive to the usual line of treatment. Detailed clinical examination and inquiry into the case history revealed turpentine poisoning.

Adolescent↗
PubMed1994

Pulse oximetry during lumbar epidural anesthesia: reliability of values measured at the hand and the foot.

Pulse oximetry is dependent upon the presence of a pulsating vascular bed. The signal detection will be impaired in the presence of vasoconstriction or venous congestion, conditions which may occur readily in clinical practice. We compared the oximetric measurements (SpO2) at the hand and the foot with arterial hemoglobin saturation (SaO2) during lumbar epidural anesthesia. After administration of a crystalloid solution (20 mL/kg body weight lactated Ringer's solution), 40 adult male patients, scheduled for inguinal hernioplasty, received 15 mL of 0.50% plain bupivacaine into the lumbar epidural space. Two pulse oximeter probes were applied to the index finger and toe of the patients, and the SpO2 values were recorded continuously. Arterial hemoglobin saturation (SaO2) was measured using a co-oximeter 5 min before and 30 min after the onset of sensory block. No significant differences were detected between SaO2 (97.7%, SD 0.4%) and SpO2 basal values recorded from the hand (97.8%, SD 0.8%) and the foot (98.1%, SD 0.4%). After the onset of epidural anesthesia, a progressive decrease of SpO2 value recorded from the hand was observed: at 30 min it was 92.3% +/- 1.3% (P < 0.01 compared with baseline). At the same time, the SaO2 value was 97.5% +/- 0.9% (P < 0.01 compared with SpO2 from the hand). On the contrary, no significant difference from both basal value and SaO2 was detected in SpO2 measurements from the toe during the epidural block. In all patients intraoperative decrease of heart rate and arterial blood pressure was < or = 15% from baseline.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Dapsone agranulocytosis in a leprosy patient.

Dapsone-induced agranulocytosis is a rare adverse effect. There are various reports of agranulocytosis in patients treated with dapsone for malaria prophylaxis and other dermatological diseases. However, this adverse reaction in leprosy is not often encountered. We describe agranulocytosis in a young patient who was taking dapsone (100 mg) for borderline-tuberculoid leprosy in a rural environment.

Adult↗