Contrast enhancement as an aid to interpretation in digital subtraction radiography.

An initial study was performed to demonstrate the feasibility of pseudocolor contrast enhancement technique in digital subtraction radiography (DSR). DSR is an electronic image processing technique that has been shown to be of greater diagnostic value in the detection of small periodontal bone lesions than conventional radiography. Pseudocolor enhancement involves selectively assigning a unique color to each shade of gray present in a black-and-white subtracted image. Two image enhancement techniques were developed and tested in a phantom system consisting of extracted teeth set in blocks of plaster mixed with sawdust to simulate trabecular bone. It was found that experimentally induced periodontal lesions were more readily detected by the average clinician in both types of enhanced subtraction images than unenhanced subtractions. Furthermore, both enhancement techniques were of significantly greater diagnostic value for lesions smaller than 1.0 mm (p less than 0.001). The technique that colored an isolated area of interest was significantly more diagnostic at all depths tested (p less than 0.001 at 0.5 and 1.0 mm, and p less than 0.05 at 0.5 mm). Contrast enhancement may be a significant aid to the average clinician for the interpretation of DSR and the detection of small periodontal defects.

[The dangerous blood clot in orthopaedic surgery (author's transl)]. / Le caillot dangereux en chirurgie orthopédique. Résultats d'une enquête par phlébographie pré- et post-opératoire des membres inférieurs.

104 patients who had been subjected to an orthopaedic procedure such as total hip prosthesis, knee prosthesis, or upper femoral osteotomy, have been studied by pre- and post-operative phlebographs. Calcium heparinate was given systematically after operation. It was noted that despite this regime, half of the patients showed thrombosis. The "dangerous" clot was situated in a main venous trunk and was unattached. Out of 79, 40 clots were said "dangerous". Four emboli were observed, of which one was fatal. Total hip prostheses were less dangerous than knee prostheses or osteotomies. A popliteal clot was more dangerous if traction was used post-operatively, and if the dose of heparin was only a preventive dose. Curative doses limited the extent of clots formed and decreased the likelihood of migration provided medication was started early. Pre-operative injection of heparin 2 hours before operation did not decrease the number of clots. Some other risks were also analysed. It was noted that early re-operation was accompanied by a very high risk. In such cases, preventive occlusion of the inferior vena cava may be justified.

[The relationship between synovial plicae and patellar chondropathy (author's transl)]. / Pli synovial interne et chondropathie rotulienne. A propos de 13 cas opérés.

The authors describe the possibility of an anomaly of the plica synovialis in cases of patellar pain and disturbance of function on the medial sides of the knee. A diagnosis is bases on the study of arthrography, associated with patello-femoral views. Thirteen knees have been operated on; the types of lesions of the synovial plicae and possible associated lesions of the patellar cartilage are described.

[A nerve root anomaly with lumbar disc prolapse. Report of a case (author's transl)]. / Sciatique paralysante bilatérale par hernie discale et anomalie radiculaire. A propos d'un cas.

A case of sciatica with partial paralysis of both lower limbs is reported. At operation a prolapse of the L4/5 intervertebral disc on the right side was associated with an anomaly of the left fifth lumbar root which was lower and more horizontal than normal. The authors give a short review of the literature.