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A De Agostini

Publications and source records attributed to A De Agostini.

10 recordsLinked to original sources
PubMed1992

A motion correction algorithm for an image realignment programme useful for sequential radionuclide renography.

The correction of organ movements in sequential radionuclide renography was done using an iterative algorithm that, by means of a set of rectangular regions of interest (ROIs), did not require any anatomical marker or manual elaboration of frames. The realignment programme here proposed is quite independent of the spatial and temporal distribution of activity and analyses the rotational movement in a simplified but reliable way. The position of the object inside a frame is evaluated by choosing the best ROI in a set of ROIs shifted 1 pixel around the central one. Statistical tests have to be ful-filled by the algorithm in order to activate the realignment procedure. Validation of the algorithm was done for different acquisition set-ups and organ movements. Results, summarized in Table 1, show that in about 90% of the simulated experiments the algorithm is able to correct the movements of the object with a maximum error less or equal to 1 pixel limit. The usefulness of the realignment programme was demonstrated with sequential radionuclide renography as a typical clinical application. The algorithm-corrected curves of a 1-year-old patient were completely different from those obtained without a motion correction procedure. The algorithm may be applicable also to other types of scintigraphic examinations, besides functional imaging in which the realignment of frames of the dynamic sequence was an intrinsic demand.

Algorithms↗
PubMed1988

Unusual CT features in ruptures of abdominal aortic aneurysms.

The authors present two cases of impending rupture of abdominal aortic aneurysms correctly diagnosed by means of some unusual CT findings. The clinical signs were not clear. On CT examination, despite the absence of haematomas, minor, but precise, changes allowed the correct diagnosis: loss of definite contours of the aneurysm, non-homogeneous peri-aortic and peri- and para-renal adipose tissue, thickening of the renal fascia and a thin fluid collection over the psoas muscles.

Acute Disease↗
PubMed1988

[Ovarian dermoid cysts. Radiographic fat floating sign and CT diagnosis of chronic rupture].

Unsuspected chronic rupture was discovered during surgical removal of a very large ovarian dermoid cyst. Abdomen X-ray, US and CT examinations were preoperatively performed. Standing X-ray projection of the abdomen allowed the appearing of a new radiographic finding of dermoid cyst, the "fat floating" as the equivalent of the "gravity dependent layering" in US and CT features. This radiographic sign appears as an horizontal line between two soft tissues of different opacity; it is caused by oily and sebaceous fluid floating over serous fluid and over intracystic debris. Literature was reviewed and radiographic findings in dermoid cysts were reconsidered; the sign of "fat floating" could enhance the diagnostic accuracy of abdomen X-ray. So when a pelvic or an abdominal-pelvic mass is discovered in a young woman, standing projection is required for abdomen X-ray. Rupture of a dermoid cyst may happen without notice and chronically; CT has been more accurate than US in evaluating rupture, in particular the peritoneal spread of oily pseudocyst.

Adult↗
PubMed1987

[Thrombosis of the false lumen in acute aortic dissection. CT diagnosis].

Three cases are reported of acute aortic dissection with complete thrombosis of the false channel, which is a very uncommon event in De Bakey's I and II type aortic dissections. The 3 patients entered hospital because of severe thoracic pain without any ECG sign of myocardial infarction. Emergency CT showed evidence of pericardial effusion suggesting hemopericardium, enlargement of the ascending aorta and a peripheral semilunar filling defect which caused a slight deformation of the true channel. On precontrast scans, only one case showed inward displacement of peripheral intimal calcifications and high-density aortic wall. No typical signs of aortic dissection were reported, except in the first patient--where a double contrast filled lumen, separated by an intimal flap was seen. CT findings are individually discussed. It is emphasized that in all patients more than one CT sign was present at a time. The correct evaluation of these signs together with the clinical data could lead to the right diagnosis of aortic dissection in spite of the lack of a filled false channel.

Acute Disease↗
PubMedDate not supplied

[Proposal for a quality control procedure for rotating gamma camera tomographic systems].

Single photon emission computerized tomography using a rotating gamma camera needs accurate calibration of electromechanical components, detection system and reconstruction software. A complete group of quality control procedures, developed on the basis of experience and experimental data acquired using a series of widely used gamma camera SPECT systems is presented. The procedures are divided into controls related to the rotational movement. of the detector and controls on the principal physical parameters characterizing a tomographic image. All quality controls here presented were performed with commercial phantoms.

Quality Control↗