Biomedical subjects
Publications and source records attributed to G Macis.
An accurate analysis of the rectal anatomy and of its "setting" is carried out. The various anatomical structures are defined by the available imaging procedures to supply information on a reasoned combined modality imaging of rectal anatomy.
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Information technology is at present an integrating part of the department of radiology. The applications to radiology involve the new imaging procedures as CT and MRI as well as exams which to-date are performed with analog methods. Besides off-line digital conversion of images by video camera or scanner, on-line systems are available with which conventional images are directly converted to digital images. Digital radiography using photostimulable phosphors is based on the capability of barium fluorohaldeide plates to emit light when stimulated by a laser beam. Digital spot fluorography is a dedicated system which enables the digital acquisition of dynamic images. The diffusion and evolution of digital systems dedicated to conventional exams will permit in a near future a fully digital radiology department.
Thromboembolism is presently the third most frequent cardiovascular disease, with an incidence of deep venous thrombosis of 800,000 cases a year in the USA. The clinical diagnosis of the condition is difficult and noninvasive procedures are poorly reliable, which makes the diagnosis and treatment of deep venous thrombosis appropriate in the patient with clinically suspected pulmonary embolism. Color-Doppler US is now replacing phlebography in the diagnosis of deep venous thrombosis. Proximal deep venous thrombosis is always at high risk for embolism (50%). Isolated calf thrombi may spread into proximal veins and thus cause severe embolism. Therefore, the early detection of thrombus site and extent and a timely treatment before embolism are of the utmost importance. Color-Doppler US is a noninvasive technique which can show deep venous thrombosis with 95% sensitivity in the proximal and 55% sensitivity in the distal districts in asymptomatic patients. This examination must be used not only to confirm a diagnostic suspicion of deep venous thrombosis, but also to screen high-risk patient and to monitor distal thrombosis. In the secondary prophylaxis of pulmonary embolism, the radiologist must perform a mechanical interruption of inferior vena cava by positioning a caval filter. Caval filters can be temporary or definitive; standard indications for caval filter positioning are a contraindication to anticoagulant therapy and the onset of pulmonary embolism in spite of anticoagulant drugs. A further indication is the presence of floating thrombi in the femoroiliac-caval trunk. Multidisciplinary groups including the hematologist, the radiologist and the clinician should plan the diagnostic and therapeutic approach and participate in the decision-making process. In our department, from January, 1992, to June, 1995, sixty-five caval filters were positioned in 62 patients selected out of 260 candidates. Three complications only were observed; one patient had recurrent pulmonary embolism and three patient had caval thrombosis spreading beyond the filter. In 198 patients in whom no caval filter was implanted, pulmonary embolism did not recur. At present, the role of the radiologist is markedly changing, especially in the management of this condition. On the one hand, radiologists must diagnose thromboembolism as a whole and not only its pulmonary evidence; on the other hand, they play a major operational and interventional role in the treatment of thromboembolism patients.
Venous thromboembolism is a relevant social and health care problem for its high incidence, pulmonary embolism-related mortality, and long-term sequels which may be disabling. In the United States, there are at least 100,000 deaths per year from pulmonary embolism, found in over 10% non selected autopsy findings. The use of noninvasive diagnostic procedures has improved our knowledge on venous thromboembolism, with reference to surgery in particular. Deep vein thrombosis represents one of most common postoperative complications. Fatal pulmonary embolism is observed at least in one over thousand operated patients. From data of literature and in the authors' experience, the incidence of pulmonary embolism is decreasing in last years. Deep vein thrombosis is caused by several factors associated with Virchow's triad. Its evolution is site-related. While deep vein thrombosis of the calf can be considered a "benign" pathological condition for the incidence and severity of the embolic complication, as well as for the long-term outcomes, when the proximal venous trunks are involved, it is related to a high incidence of severe pulmonary embolism and relevant postphlebitic sequels. Pulmonary embolism is often the first manifestation of thromboembolism. Mobilization of thrombi is easier in the first phases, when they do not adhere as yet to the venous wall. Of 52 consecutive cases of pulmonary embolism, 21% occurred in the absence of signs or symptoms of deep vein thrombosis. In rare cases, thrombosis may be massive with total block of venous return flow and onset of ischemia. These forms have a severe prognosis apart from the embolic complication.
Chest radiograph plays a major role in patients with suspected pulmonary embolism because it frequently allows the visualization of the radiologic signs of pulmonary embolism without or with infarct while at the same time the presence of other diseases which mimic it, can be detected. Combined with other investigations this finding allows the precise diagnosis of a higher number of diseases while other diagnostic exams can be selected. Numerous radiologic signs are visualized. They involve the vascularization, the parenchyma, the pleura and diaphragms. They allow to distinguish between embolism with infarct from embolism without infarct. They require a global interpretation to attribute a diagnostic role to chest radiograph. This should be carefully performed to represent a valid support to the diagnostic approach.
Venous thromboembolism shows a high incidence and a significant mortality. Even if valid methods are available, thromboembolism is underdiagnosed. There are a number of diagnostic difficulties. They concern the time of the diagnostic suspicion, the patient selection for the various procedures and their combination. These difficulties may be overcome by team work where specialists of different disciplines (surgeons, internists, experts in nuclear medicine, radiologists) integrate their competence to attain the established objectives. The integration results in "synergism", namely an added value greater than the sum of competences of the team components. Thus, an operational unit active 24 hours over 24 must be formed to diagnose and treat the largest number of cases of thromboembolism. To establish the clinical suspicion of thromboembolism is the first indispensable step for patient selection. Thromboembolism should be investigated in all patients with chest pain, dyspnea and tachypnea in the absence of preexisting cardiorespiratory disease. The team should evaluate the impact of signs and symptoms to establish a definitive clinical probability which can direct towards the suitable, least invasive imaging procedure. Perfusion scanning, when highly suggestive or normal, is conclusive. However in 70% of cases it is indeterminate. Thus it should be combined with other procedures and with the clinical assessment. In practice, many dubious cases remain unsolved. The team work represents an organizational response to this diagnostic and therapeutic inadequacy. The real change in strategy which has revolutionized the diagnosis of thromboembolism was the widespread use of color Doppler US in the diagnosis of deep vein thrombosis. Since pulmonary embolism as well as deep vein thrombosis are treated with the same therapy, it is adequate to document the thrombosis also in the absence of a definitive demonstration of embolism. The old-fashioned approach should be reversed and the investigation should be centered on the assessment of deep vein thrombosis: site, emboligenic potential, floating extremity and extension. The integration of the clinical assessment, scanning finding and color Doppler US lowers by about 20% the number of indeterminate cases and indicates the patients for whom pulmonary spiral CT or pulmonary angiography is required. In all patients with cardiorespiratory insufficiency still unsolved after the combination of noninvasive exams, pulmonary angiography or spiral CT is mandatory because of the high risk for death. The remaining ones can be followed with serial color Doppler US exams. The cost/benefit ratio shows that the noninvasive strategy is the least expensive, the least hazardous and the most effective. At present, effective therapies are available for thromboembolism. Standard heparin and low molecular weight heparin fractions, fibrinolytic agents, surgery and recently caval filters are playing a major role in secondary prophylaxis of pulmonary embolism. The therapeutic approach is conditioned by various factors: the features of thrombosis, the presence and entity of pulmonary embolism, the patient cardiorespiratory condition, possible contraindications for anticoagulant and fibrinolytic agents. The presence of such a number of variables makes the use of a therapeutic algorithm, difficult. In this phase, based on our experience we believe that the present solution lies in the activity of an operational team of experts who establish the treatment to be performed.
In functional radiology of the lung, the depiction of subtle details of circulatory and bronchial anatomy, is very important. At present, the evolution of the radiographic techniques allows to overcome the difficulty in imaging, essentially related to the marked difference in density of chest structures, producing radiographs optimized to the concomitant representation of the parenchyma and higher absorption structures. Main quality factors related to radiation beam optimization on one hand and to imaging systems on the other hand, are considered with an analysis of the evolution of methods and techniques of thoracic radiology.
Pulmonary tuberculosis in its primary and postprimary form is a widespread disease. Radiologic and CT findings in the acute phase of the disease, its many different aspects, as well as the alterations observed following the outcomes of tuberculosis at the parenchymal and pleural level, are examined.