Biomedical subjects
Publications and source records attributed to P Aerts.
Three cases of avascular necrosis of the scaphoid are reported. One patient, who was using corticosteroids on a regular basis, had other areas of bone necrosis. None of the patients had a history of trauma. All three patients were treated with proximal row carpectomy with satisfactory results.
We report a case of pulmonary lymphangiomyomatosis in a young female. CT--and especially high resolution CT--is more specific and sensitive than chest radiography in showing the lung abnormalities. Pathognomonic CT findings are the presence of thin walled cystic air spaces spread throughout the lung parenchyma without nodules and without regional predominance and mostly surrounded by normal parenchyma. The superposition of the multiple thin walls of the cysts is responsible for the reticular interstitial pattern observed at chest radiography.
Flow in high-resistance peripheral vessels of the extremities is characterized by a short period of positive flow during systole and almost no flow during diastole. Hence, time-of-flight sequences for MR angiography in high-resistance peripheral vessels are successful only when applied in a plane perpendicular to the vessel course. When applied in a plane parallel to the vessel, the method suffers from the rapid saturation of the inflowing spins. Gadopentetate dimeglumine-polylysine is a new T1 relaxation agent with blood-pooling capability that can be used to prevent blood saturation. In the present study it produced excellent angiograms in rabbits at a dose of 0.01-0.08 mmol/kg injected IV. Time-of-flight angiograms were acquired in a 1.5-T superconducting magnet with a three-dimensional fast imaging with steady precession sequence, 20,40/10/20 degrees (TR/TE/flip angle), with an acquisition volume of 200 x 200 x 60 mm, 64 partitions, and velocity compensation in the slice-selection and frequency-encoding directions. Arteries and veins smaller than 1 mm were visualized over the entire length of the posterior limbs. If ongoing studies confirm the low toxicity of this new agent, gadopentetate dimeglumine-polylysine could offer a totally new approach to MR angiography.
Thirty nine patients with one or more focal hepatic lesions were examined by contrast enhanced computed tomography (CE-CT) and magnetic resonance imaging (MRI). A variety of pulse sequences--spin echo (SE), gradient echo (GE) and inversion recovery (IR)--have been reported in the literature on MRI concerning the detection and characterization of liver tumors. Multiple studies have compared MRI at different field strengths to CT. As controversy still exists concerning the optimal pulse sequence on MRI, CE-CT has been compared to T2 weighted SE sequence in this study. CT, as well as MRI, identified abnormalities in liver parenchyma in all patients. As far as detection of hepatic lesions is concerned, MRI and CE-CT were equal in 35 cases and MRI was superior in the other four cases. However, CT remains the examination of choice for detection of focal lesions, due to the short examination time, the low cost and the superiority in detection of extrahepatic pathology.
A case of chondroblastoma with invasion of the joint via the attachment of the posterior cruciate ligament is reported. The importance of careful interpretation of early radiological signs and the usefulness of conventional tomographic and computerized axial tomographic examination is demonstrated, and a method for reconstruction of the defect using an AO buttress plate and bone chips is presented. There was no sign of recurrence two and a half years postoperatively.
An algorithm for hidden-line removal in graphical reconstructions of serially sectioned biological objects is developed for PC-like computer configurations. The aim is to handle complicated structures defined by vast numbers of coordinate pairs and intersections between contours, without requiring excessive computing time. The procedure depends upon a fast searching routine for the localization of intersections and visibility.
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The presented software package fulfills the need for processing serial sections with a microcomputer configuration, enabling three-dimensional reconstruction with hidden line removal. The language used is an interpreted BASIC-dialect (HPL). The input is performed via an interactive program. The object can be rotated in space. The Hidden Line algorithm does not depend upon a raster technique. Points of intersection of successive contours are calculated and inserted, thus providing drawings of high resolution and quality. The handling time can be said to be short, especially when considering the capacities of the microcomputer configuration used.
The determinants of opsonic defense to Staphylococcus epidermidis were studied in 47 premature newborns. Opsonic activity for S. epidermidis in serum from premature newborns proved to be proportional to gestational age (r = .664, P less than .001). The level of IgG antibodies to staphylococcal peptidoglycan in neonatal sera was similarly proportional to gestational age (r = .604, P less than .001). However, all opsonic activity of premature neonatal serum proved to be heat labile, i.e., dependent on activation of complement. Thus, no heat-stable, IgG-dependent opsonic activity to S. epidermidis was detected in any of the preterm sera, despite the presence of IgG antibodies to peptidoglycan. Further studies with purified IgG isolated from paired sera from term neonates and their mothers revealed that at similar concentrations the opsonic activity to S. epidermidis of neonatal, transplacentally derived IgG was only 26% of the activity of maternal IgG, a finding that may explain the absence of heat-stable opsonic activity in preterm newborns.
Most MR angiography (MRA) techniques use macroscopic blood motion to characterize the flowing spins. A different approach is represented by the use of contrast enhancement of blood pooling agents. The intravenous injection of one of these agents, namely Gd-DTPA polylysine, produces a shortening of the blood T1 below the T1 values of fat and soft tissues. In this study on experimental MRA in rabbits, we used an imaging sequence with a 90 degrees saturation pulse and a 180 degrees inversion recovery pulse. Both the saturation and inversion recovery times were adjusted to suppress the signals of soft tissues and fat. The remaining ultrashort T1 blood was imaged with a projective velocity refocused spin echo or gradient echo sequence. Magnetic resonance angiography provided excellent vessel detail with a 30-60 s acquisition time. In addition, there was no need for further processing after image acquisition because the projection was obtained immediately. The disadvantages of the technique are the need for contrast medium injection and the nonselectivity of MRA.
The case of an 11-year-old boy with an ischemic contracture of the forearm and hand, initiated by a minor injury, is reported. Awareness of the syndrome, careful examination, and observation are emphasized. The decompression must include opening of all the tight fascial envelopes.