Direct radiographic magnification in combination with digital radiography for bone imaging

The usefulness of direct radiological magnification is inversely related to the resolution of film-screen systems when very small focal spots are used. Thus, spatial resolution of digital luminescence radiography (DLR) may closely approximate that of high-detail screens at the expense of a more restricted field of view. Apart from the major drawback of limited spatial resolution, DLR makes it possible to take full advantage of image-processing techniques and an unmatched dynamic range.     

Direct radiographic magnification in dental radiology

Panography using small focal spots was an accepted radiodiagnostic method in dentistry before it was replaced by pantomography. Meanwhile, a new microfocus X-ray tube with a much smaller focal size is available. In comparison with the former focal system no new aspects are discernible. On the other hand, the new tube will be especially helpful for preparative diagnostic work before histological evaluations.     

Direct radiographic magnification in experimental medicine

Some aspects of direct radiological magnification in experimental medicine are shown by teratological investigations of the fetal rat skeleton and by indirect lymphadenography in rabbits. A combination of microfocal radiography and high-resolution non-screen films or digital image processing allows the evaluation of structures with a minimum size of 5 microns. Pseudo-3D images correlate directly with scanning electron micrographs of equivalent casts. Therefore radiography with direct magnification can make difficult preparations and time-consuming staining processes unnecessary. Besides saving time, the main advantage of this method is the amount of new information it yields. For the first time, for example, the filling mechanism becomes visible even in minute vessels, such as the intranodal sinuses, which measure about 10 microns. Hitherto, we have only been able to infer this mechanism from histological specimens. A further benefit of direct radiological magnification over the conventional microscopical method is the smaller number of experimental animals needed.     

Direct radiographic magnification with computed radiography

Computed radiography was combined with a 0.1-mm microfocus radiographic tube to obtain radiographic magnification of a x3 to x5. Gray-scale image processing compensated for the loss of radiographic contrast associated with the high-kilovoltage, short-exposure technique. The high-pass spatial frequency filtering capability of the computed radiography resulted in enhanced edges and increased displayed latitude. The improved image quality obtained by magnification computed radiography allowed delineation of subtle abnormalities and small anatomic structures not apparent on conventional screen-film contact or magnification radiographs.     

Direct radiographic magnification and radiation exposure

The advantage of microfocal X-ray units is the production of high-resolution magnification radiographs. Up to a magnification of x 4 the exposure equals that of a conventional radiograph. Some filter materials have been tested, aluminium filtration was found to be the best choice.     

Direct radiographic magnification: a contribution to the study of bone pathology

Direct magnification radiography was evaluated on 46 patients with skeletal disorders. The equipment employed was based on a microfocus tube and it gave a magnification factor of 3 X. This technique was judged to be more useful than standard X-ray films in 35/46 cases (76%). The size of the part examined played an important role in the effectiveness of this technique, since the most useful and impressive results were obtained in thin anatomic sites, like the extremities. The highest value of direct magnification radiography was found to be in uraemic osteodistrophy, in particular for the study of the hands. This technique appeared to be very useful also in bone tumours, since it allowed a detailed evaluation of the trabecular structure and of the cortical outline.     

Direct radiographic magnification in experimental research on the stomatognathic system

A new X-ray tube with a less than 10 microns microfocus enables investigations supported by direct radiological magnification. It allows the nondestructive examination of mineralized structures up to microscopic dimensions. For experimental research on bony tissue, teeth and in the field of dental material science, new and interesting areas have been opened. Examples demonstrate possibilities of this special radiographic method.     

Direct radiographic magnification of the hands. A critical analysis

The value of direct magnification radiography of the hand and the wrist has been studied in 128 patients affected by rheumatic diseases. Only in a small group (3.17%) magnification determined a higher percentage of correct diagnosis; in the 17.06% of cases direct magnification radiography provided useful increase in information but did not change the diagnosis correctly reached by conventional techniques. In most cases (79.76%) magnification provided only a better image quality but no more information helpful for the diagnosis, because of the high level achieved by conventional techniques. Therefore direct magnification radiography must be used only in selected cases and not as routine radiographic technique.     

Direct radiographic magnification: evaluation of three microfocus x-ray tubes

Three microfocus x-ray tubes (RSI, Siemens, and Eimac) were evaluated for their focal and imaging characteristics. The RSI and Siemens focal spots had similar homogeneous radiation intensity distributions. The Eimac tube had an asymmetric intensity distribution. Because of their focal spot characteristics, the RSI and Siemens tubes provided superior magnification radiographs for small objects. The Siemens and Eimac tubes were preferable for magnification of thick objects because their larger object-film air gap reduced scattered radiation reaching the film.     

Direct radiographic magnification of the hand: study of erosions in rheumatoid arthritis

Plain films and direct magnification radiographs of the hands were performed in 34 patients affected by rheumatoid arthritis, using mammographic x-ray tube, achieved with 0.1 mm microfocus, and 1.85 X magnification factor. Direct magnification radiography has provided essential or useful diagnostic data in 44% of cases, particularly in recognizing early skeletal erosions. Nevertheless direct magnification radiography must be used only in those cases in which traditional mammographic techniques do not supply satisfactory results.     

Direct magnification radiography in pediatric radiology

Some indications in which direct magnification radiography might be useful in the diagnosis of newborns and infants are illustrated. We believe direct magnification radiography is useful especially in respiratory distress syndrome, suspected aspiration of amniotic fluid and meconium, suspected pneumonia, mediastinal pathology, in newborns and infants and metabolic and inflammatory diseases of the skeletal system in older children.     

Pulmonary infections after bone marrow transplantation: clinical and radiographic findings

PURPOSE: To assess the clinical and radiographic findings of pulmonary infections diagnosed by using invasive means. MATERIALS AND METHODS: Fifty-nine episodes of pulmonary infection were diagnosed in 52 (7.2%) of a consecutive series of 725 adult bone marrow transplant recipients. Causative organisms, time of diagnoses, radiographic patterns, and mortality rates were reviewed. RESULTS: Cytomegalovirus and Aspergillus species were the two most common pathogens, accounting for 22 and 17 episodes, respectively. During the first 30 days after bone marrow transplantation, fungi caused the majority (nine [82%] of 11 episodes) of pulmonary infections; from days 31 to 100, viruses predominated (21 [62%] of 34 episodes). Recipients of allogeneic transplants had a higher probability of developing Cytomegalovirus pneumonitis than did the recipients of autologous and syngeneic transplants (P < .001). Radiographic findings of Cytomegalovirus pneumonia consisted of parenchymal opacification (90%) and innumerable nodules smaller than 5 mm (29%); in two patients, radiographs were normal. Nodules, masses, or nodules and masses, present in nine (69%) of the 13 patients with Aspergillus infection, were the most common radiographic findings in invasive aspergillosis. Bone marrow transplant recipients with a documented pulmonary infection were found to have a lower event-free survival than recipients without infection (P < .001). CONCLUSION: Opportunistic pathogens account for the majority of pulmonary infections requiring invasive diagnosis and tend to manifest at predictable times in the course of events following recovery from bone marrow transplantation. Cytomegalovirus, the most common pathogen, causes a spectrum of radiographic findings that includes normal findings. Occurrence of a pulmonary infection is associated with an increased mortality rate.