Tuning of automatic exposure control strength in lumbar spine CT.

OBJECTIVE: To investigate the impact of tuning the automatic exposure control (AEC) strength curve (specific to Care Dose 4D®; Siemens Healthcare, Forchheim, Germany) from "average" to "strong" on image quality, radiation dose and operator dependency during lumbar spine CT examinations. METHODS: Two hospitals (H1, H2), both using the same scanners, were considered for two time periods (P1 and P2). During P1, the AEC curve was "average" and radiographers had to select one of two protocols according to the body mass index (BMI): "standard" if BMI <30.0 kg m(-2) (120 kV-330 mAs) or "large" if BMI >30.0 kg m(-2) (140 kV-280 mAs). During P2, the AEC curve was changed to "strong", and all acquisitions were obtained with one protocol (120 kV and 270 mAs). Image quality was scored and patients' diameters calculated for both periods. RESULTS: 497 examinations were analysed. There was no significant difference in mean diameters according to hospitals and periods (p > 0.801) and in quality scores between periods (p > 0.172). There was a significant difference between hospitals regarding how often the "large" protocol was assigned [13 (10%)/132 patients in H1 vs 37 (28%)/133 in H2] (p < 0.001). During P1, volume CT dose index (CTDIvol) was higher in H2 (+13%; p = 0.050). In both hospitals, CTDIvol was reduced between periods (-19.2% in H1 and -29.4% in H2; p < 0.001). CONCLUSION: An operator dependency in protocol selection, unexplained by patient diameters or highlighted by image quality scores, has been observed. Tuning the AEC curve from average to strong enables suppression of the operator dependency in protocol selection and related dose increase, while preserving image quality. ADVANCES IN KNOWLEDGE: CT acquisition protocols based on weight are responsible for biases in protocol selection. Using an appropriate AEC strength curve reduces the number of protocols to one. Operator dependency of protocol selection is thereby eliminated.

Caustic intoxication.

After a retrospective study of 17 cases of caustic intoxication in the intensive care unit, the epidemiologic, pathophysiologic, clinic and therapeutic aspects are reviewed. The following procedure is suggested: early endoscopies, abstention of any gastric lavage, corticosteroids and empiric antibiotic therapy and the most early possible introduction of a parenteral nutrition.

[Neoplastic invasion of the pulmonary arteries. Evaluation by MRI. Preliminary experience]. / Envahissement néoplasique des artères pulmonaires. Evaluation par IRM. Expérience préliminaire.

Bronchial tumors invading the mediastinum are no longer systematically regarded as inoperable. Curative surgery has produced a significant survival rate and led to the adaptation of the TNM classification. The degree of invasion of the pulmonary artery is a criterion of operability. The authors are trying to assess the role of MRI with regard to CT and DSA for the measurement of invasion. Their study deals with the prospective assessment of ten patients. The MRI examinations have been carried out with a 0.5 and 1.5 T supraconductive magnet (Philips Gyroscan). Cardiac gating has been used for acquisition. The planes of section are axial, transverse or oblique along the greater axis of the pulmonary arteries. CT examinations in 9-mm thick sections with and IV contrast injection demonstrate the contact of the tumor with the mediastinum. The digital angiograms have been taken with an intravenous injection into a vein of the bend of the elbow or into a femoral vein. Six cases have been verified at surgery. In all cases, the invasion predicted with MRI proved to be correctly assessed. In three cases, MRI provides additional information to the combined findings of CT and DSA. MRI is a good complement for the preoperative assessment of patients with large tumors invading the mediastinum but for which curative surgery is indicated.

[Case of acute poisoning by mercuric oxycyanide]. / A propos d'un cas d'intoxication aigue par oxycyanure de mercure.

We report the case of a 25-year-old woman who voluntary swallowed mercuric oxycyanide and presented an anuric acute renal failure. The treatment was classically based upon the use of chelating agents and haemodialysis. Recovery of renal function was excellent. We discuss then more widely the clinical, physiopathologic and therapeutic aspects of acute intoxication with inorganic mercury salts.

Development of controlled Nd:YAG laser for medical applications.

Several medical fields are concerned with applications of thermal lasers such as neodymium-doped, yttrium aluminum garnet (Nd:YAG), argon, and CO2. However, quantification of the necrotic volume of Nd:YAG laser-induced damage is not possible at the time of treatment. Mathematic models and feedback control can help to optimize Nd:YAG laser treatments. We therefore formulated mathematic models for coagulation processes and developed an intelligent Nd:YAG laser system with closed-loop feedback control. Surface temperature evolution proved to be valuable data for real-time control of coagulation and ablation. Infrared thermometry provided the noncontact measurement of temperature. A computer stored the temperature data calculated by the mathematic model. Deviations of surface temperature during the treatment beyond established tolerances causes the Nd:YAG laser system to adjust the laser power automatically.

Thermal effects of lasers on dental tissues.

The thermal effects of Nd:YAG, argon, and CO2 laser beams are observed on enamel, dentin, and dental pulp by means of computerized infrared thermography and thermocouple. This study shows that the Nd:YAG laser beam deeply diffuses through the enamel and dentin to the pulp. The argon laser effects are inconsistent depending on whether the enamel surface is cleaned, but after cleaning, the superficial and deep temperatures are low. With the CO2 laser, the enamel and dentin surfaces reach very high temperatures, but only low temperatures are measured in the pulp chamber.

[Clinical diagnosis of pulmonary embolism]. / Diagnostic clinique de l'embolie pulmonaire.

Pulmonary embolism, a major complication of thromboembolic disease, remains an important cause of mortality, both in surgical and medical practice. In recent literature, one finds two different currents: the first one asserts that pulmonary embolism is overdiagnosed and, therefore, "overtreated" with iatrogenic hemorrhagic complications, when other authors assert that pulmonary embolism is underdiagnosed and "undertreated". It is obvious that clinical diagnosis of non massive, acute pulmonary embolism remains difficult and that the classical triad pleuritic chest pain, hemoptysis and signs of deep venous thrombosis is not frequently found. The clinician should be attentive to the different symptoms and clinical signs which might arouse a suspicion of pulmonary embolism. A large range of investigations is available to confirm the clinical diagnosis. In deep venous thrombosis preceding or accompanying pulmonary embolism, treatment should be instituted at the first signs of venous attack. A precise diagnosis will secondarily be confirmed by phlebography. Any delay in effective early treatment of thromboembolic disease will increase the risk of pulmonary embolism and of the mortality inherent in this dreadful complication.

Changing echocardiographic features of a hydatid cyst of the heart.

A 24 year old woman with pulmonary embolism and a past history of echinococcal disease underwent echocardiography which detected two cysts in the right ventricle which became more solid after treatment with mebendazole. The surgical and pathological findings confirmed the presence of the two cysts and the hydatid nature of the lesion.