Establishment of diagnostic reference levels in cardiac CT in France: a need for patient dose optimisation.

The objective of this study was to propose diagnostic reference levels (DRLs) for coronary computed tomography angiography (CCTA), in the context of a large variability in patient radiation dose, and the lack of European recommendations. Volume Computed Tomography Dose Index (CTDIvol) and dose-length product (DLP) were collected from 460 CCTAs performed over a 3-month period at eight French hospitals. CCTAs (∼50 per centre) were performed using the routine protocols of the centres, and 64- to 320-detector CT scanners. ECG gating was prospective (n = 199) or retrospective (n = 261). The large gap in dose between these two modes required to propose specific DRLs: 26 and 44 mGy for CTDIvol, and 370 and 970 mGy cm for DLP, respectively. This study confirms the large variability in patient doses during CCTA and underlines the need for the optimisation of cardiac acquisition protocols. Availability of national DRLs should be mandatory in this setting.

[Complications of myocardial infarction]. / Complications de l'infarctus du myocarde.

Most acute complications of myocardial infarction do not need emergency imaging, since they often result in death prior to hospital admission: ventricular fibrillation and tachycardia, papillary muscle or septal rupture, fissuration and tamponade. Imaging can play a role at distance of the acute phase (papillary muscle dysfunction, false aneurysm, development of a mural thrombus associated to left ventricular apical dyskinesis, with potential embolic complications).

Technical developments in cardiac CT: 2000 update.

Preliminary results of the new generation CT scanners in the study of the heart and coronary arteries, are reported, after an overview of basic anatomy, physiology and main technical problems. Comparison is made with the other conventional procedures. The clinical validation of cardiac CT is under way while preliminary results are very encouraging. However, for cardiac CT to become an examination of first choice in the study of the heart and coronary arteries, spatial resolution should be improved and acquisitions of 15 cm volume with less than 15 sec breath-hold should be feasible. The improvement in cardiac synchronization and temporal resolution will allow a kynetic systolic as well as diastolic study. This is going to be possible with the new generation CT scanners able of 16 or 32 sections per second.

Criteria for anatomical compatibility of the total artificial heart: computerized three-dimensional modeling of the cardiovascular anatomy.

A quantitative study of cardiovascular anatomy was performed by obtaining three-dimensional reconstructions from regular computed tomography scan images in 15 patients, all candidates for heart transplantation. Volumetric estimates of the cardiovascular structures were obtained from these three-dimensional reconstructions using data directly related to total artificial heart (TAH) implantations. By using computerized three-dimensional modeling of these structures, reproducible measurements of the parameters defining the shape and the anatomical connections of the intrathoracic space available for TAH implantation could be derived. The results are intended to be used for both technical and clinical applications such as computer-assisted drawing of the pericardial cavity and the anatomical connections (useful for improving the design of TAH) and combined statistical calculations (multiple regressions, cluster algorithm) of the measurement results, which will then enable the best selection to be made among two or three TAH models for each patient.

[Technic for digitalized angiography of the legs by unilateral femoral artery puncture and programmed displacement of the examination table. Apropos of 56 cases]. / Technique d'angiographie numérisée des membres inférieurs par ponction artérielle fémorale unilatérale et déplacement programmé de la table d'examen. A propos de 56 cas.

The authors describe a technique for digital subtraction angiography of vessels of the legs, performed in 56 patients for suspicion or control of peripheral vascular disease. Owing to an unilateral femoral arterial puncture and a programmed moving of the table top, a subtraction arterial mapping of the two legs is obtained with only two injections of contrast medium. On the side of the puncture the arterial opacification is always very satisfactory. On the other side opacified by reflux the popliteotibial region is visualized in 95% of cases. We had no complication with iodine or arterial puncture. Our technique is then characterized by its simplicity and a small trauma owing to the unilateral puncture and the reduction of contrast medium injections.

[Pelvimetry by digitalized radiography]. / Pelvimétrie par radiographie numérisée.

We studied the ability of digital radiographs generated on a computed tomography scanner to replace conventional pelvimetry. Two digital radiograph's and one CT section permit us to measure the maternal pelvis. The anteroposterior digital radiograph allows measurement of the maximum transverse and median transverse diameters of the pelvic inlet. These two distances are corrected for magnification after reference to the lateral digital radiograph and to a graph determined owing to a phantom. The anteroposterior digital radiograph also permits to perform a CT section passing through the ischial spines with direct measurement of the inter spinous diameter. The lateral digital radiograph gives us the true values for the anteroposterior diameter of the pelvic inlet, the low sagittal diameter, the cord and the rise of the sacrum. The dosimetry studies demonstrated that maternal skin doses and fetal gonad doses were very low. Pelvimetry using digital radiography is a simple and rapid to perform procedure which offers the advantage of low radiation exposure to both fetus and mother and a high accuracy of measurement.

Histographic studies in computed tomography of contrast-enhanced cerebral and orbital tumors.

The density distribution inside a pathologic zone before and after contrast enhancement has been studied in the computed tomograms of 88 cases of cerebral and orbital tumors, using histographic analysis. The histograms provided additional diagnostic information, especially for vascular tumors. This method is also useful for experimentation with contrast media.

[The contribution of nephro-urotomography in the diagnosis of unilateral non-functioning kidney in the adult (author's transl)]. / Apport de la néphro-urotomographie au diagnostic des mutités rénales unilatérales de l'adulte

The aetiological diagnosis of a unilateral nonfunctioning kidney is achieved by angiographic or retrograde techniques. Pyelography indicates only that organ is non-functioning. 71 patients were explored by nephro-urotomography carried out using high doses of contrast medium (2 cm3/kg) with rapid injection (10cm3/sec.) and repeated tomographic sections taken during the first minute after injection. These tomographic sections, three in number, made it possible to study the three phases of the nephrogram: cortical nephrography, cortico-medullary nephrography and tubular nephrography. The aim of this study was to assess the contribution of this technique in the aetiological diagnosis of a unilateral non-functioning kidney. In the majority of cases it is possible to suspect the vascular or neoplasic origin of the non-functioning kidney. Obstructive non-functioning kidneys have two distinct nephrographic appearances. Pelvic and retroperitoneal obstructions are visualised chiefly during the phase of cortical nephrography, which shows marked parenchymatous atrophy with the presence of rounded intrarenal lacunae. By contrast, obstruction secondary to pyelo-ureteral junction syndrome results in total destruction of the parenchyma. The phenomenon of total corporeal opacification plays a major role in the visualisation of the fibrous speta which form the limits of the pseudocystic pockets. In these patients, the contribution of study of early nephrograms is less evident. Bacillary non-functioning kidneys have an analogous appearance characterised by the particular frequency of abnormal opacities, calcified ormastic. Thus the aetiological diagnosis of a unilateral nonfunctioning kidney may be obtained in the majority of cases. This permits more judicious selection of those cases requiring angiography or retrograde exploration necessary to pre-operative assessment.