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Biomedical subjects

H Kantor

Publications and source records attributed to H Kantor.

15 recordsLinked to original sources
PubMed1998

Cocaine decreases cortical cerebral blood flow but does not obscure regional activation in functional magnetic resonance imaging in human subjects.

The authors used functional magnetic resonance imaging (fMRI) to determine whether acute intravenous (i.v.) cocaine use would change global cerebral blood flow (CBF) or visual stimulation-induced functional activation. They used flow-sensitive alternating inversion recovery (FAIR) scan sequences to measure CBF and blood oxygen level-dependent (BOLD) sensitive T2* scan sequences during visual stimulation to measure neuronal activation before and after cocaine and saline infusions. Cocaine (0.6 mg/kg i.v. over 30 seconds) increased heart rate and mean blood pressure and decreased end tidal carbon dioxide (CO2). All measures returned to baseline by 2 hours, the interinfusion interval, and were unchanged by saline. Flow-sensitive alternating inversion recovery imaging demonstrated that cortical gray matter CBF was unchanged after saline infusion (-2.4 +/- 6.5%) but decreased (-14.1 +/- 8.5%) after cocaine infusion (n = 8, P < 0.01). No decreases were detected in white matter, nor were changes found comparing BOLD signal intensity in cortical gray matter immediately before cocaine infusion with that measured 10 minutes after infusion. Visual stimulation resulted in comparable BOLD signal increases in visual cortex in all conditions (before and after cocaine and saline infusion). Despite a small (14%) but significant decrease in global cortical gray matter CBF after acute cocaine infusion, specific regional increases in BOLD imaging, mediated by neurons, can be measured reliably.

Adult↗
PubMed1993

Time of flight quantification of coronary flow with echo-planar MRI.

Detection and quantification of flow of the left anterior descending (LAD) coronary artery in healthy volunteers are demonstrated using echo-planar imaging (EPI). A time-of-flight (TOF) model was used to derive coronary flow velocities from wash-in curves, free of cardiac wall motion contamination. Short-axis cardiac studies were performed using a gated, gradient echo EPI technique to limit the effect of cardiac wall motion on coronary vessel imaging. A series of 10 to 20 single or multislice images were acquired within a single breath-hold. Real-time cine series showed the LAD coronary artery with a detectability of 91% (n = 23) and revealed beat-to-beat variability in vessel position of a magnitude equal to or greater than its diameter. Flow velocity was measured in the proximal portion of the artery at rest and during exercise. The data demonstrated the known phasic pattern of LAD flow: Vsystole < or = 5 cm/s and peak Vdiastole = 14 +/- 3 cm/s (n = 11, V = mean laminar flow velocity). During isometric exercise, a LAD flow velocity increase (52 +/- 24%) was detected in eight of nine subjects. The capacity of the EPI TOF method to detect flow velocity changes should prove clinically useful for future assessment of coronary flow reserve.

Coronary Circulation↗
PubMed1987

Bone marrow pressure in osteonecrosis of the femoral condyle (Ahlbäck's disease).

Concerning the clinical, radiographic, and scintigraphic aspects of Ahlbäck's disease, there are similarities with avascular necrosis of the femoral head. In 1980, therefore, we introduced a method of measuring bone marrow pressure which had been used in cases of osteoarthritis and pain in the knee. The measurement is done in the medial and lateral femoral condyle and in the medial part of the tibial head. Our findings were increased values in all stages of the disease, indicating that early (preradiographic) diagnosis and a differential diagnosis between osteoarthritis and osteonecrosis are possible using this method alone. We treat the earliest stages by core biopsy only (the bone cylinder is sent for histological classification) and have had very good results to date.

Aged↗
PubMed1987

Cardiac function: evaluation with fast-echo MR imaging.

Magnetic resonance (MR) imaging of the heart has, to date, been limited in its ability to evaluate cardiac function. The authors have implemented a technique for functional assessment of the heart using shorter echo times than those generally used for conventional spin-echo imaging. With these short echo times, multiple images can be obtained in a multisection mode approximately within the isovolumetric phases of the cardiac cycle. This permits a pair of image stacks to be obtained, one in end systole and the other in end diastole. With the use of a modified Simpson rule, left ventricular volume and ejection fraction were calculated and compared with results obtained from contrast material-enhanced ventriculography. Preliminary results indicate that this method has promise for the evaluation of a variety of functional parameters in the heart. The short acquisition times for this functional study permit it to be combined with a tissue characterization study within the time constraints of a clinical MR imaging session.

Heart Function Tests↗
PubMed1979

[Medialisation or lateralisation in intertrochanteric osteotomies (author's transl)].

The problem of displacement of the lower fragment in intertrochanteric osteotomies is discussed. The necessity derives from alterations of the so called "mechanical axis of the limb". Ceometrical drawing and measuring of special X-ray pictures are necessary for getting exact dates for the displacement in the "frontal plain". The dependence from various biomechanical facts is shown.

Biomechanical Phenomena↗
PubMed1978

[Osteomyelitis. First experiences with P.M.M.A. chains and balls (author's transl)].

A new therapeutic principle in the treatment of osteomyelitis is introduced-as an alternative to "Suction Drainage"-, i.e. "Gentamycine P.M.M.A. chains". After exact surgical debridement a local therapy with high concentrations of antibiotic is possible. Results of the performed operations on 51 patients are encouraging after 14 months. Long term results are as yet not known.

Debridement↗
PubMedDate not supplied

[Preradiologic stage of idiopathic femur head necrosis demonstrated by intraosseous pressure measurement].

Early identification is the focal point of efforts aimed toward efficient diagnosis and treatment of osteonecrosis. With the intraosseous pressure measurement method of Ficat and Arlet it is possible to determine the onset of this disease at the preradiological stage. At the Vienna-Speising Orthopedic Clinic 11 out of a total of 66 cases of idiopathic necroses of the femoral head were diagnosed at the preradiological stage. The only treatment given in these cases was decompression by removal of a bone cylinder. The follow-up examination after an average of 22 months revealed very good results in all cases, both subjectively and roentgenologically (stage deterioration did not occur in a single case).

Blood Pressure Determination↗
PubMedDate not supplied

[Coccygodynia--a diagnostic and therapeutic problem in orthopedics].

Coccygodynia means a lot of complaints with the most important of them, namely the spontaneous pain in the coccyx, in the top of the coccyx respectively. One can differ posttraumatic coccygodynias from others, which are the symptom of other diseases like lumbar pain, sciatica, tumors in the spinal canal, visceral diseases, that means disturbances in the gynaecologic system. By the mean of 19 predominantly female patients remarkable facts of the history, of the x-ray and clinical findings are listed up and compared in three different groups. To this examination the results of longtime-results of eleven patients who have been operated are united. The resection of the "os coccygis" doesn't seem to be a satisfying possibility to influence coccygodynias caused by traumas for a long time.

Adult↗
PubMedDate not supplied

Factors influencing choice between tracheostomy and prolonged translaryngeal intubation in acute respiratory failure: a prospective study.

One of the problems of prolonged ventilatory therapy in acute respiratory failure (ARF) is the need to choose between tracheostomy after 48 to 72 hours of translaryngeal (TL) tracheal intubation or the continuous use of the TL tube for a period of 10 days. Too often the choice has been based on retrospective studies or personal preference. To investigate this problem prospectively, 52 adults in ARF were divided sequentially into 2 groups on their 3rd day of TL intubation. Patients in group I (G-I) retained the TL tube for a total of 11 days; those in group II (G-II) were tracheostomized on the 3rd day. The following factors ere used to evaluate the efficiency and complications in each group: patient's epidemiologic variables, daily pulmonary functions, severity of respiratory infections, and scores of post-intubation airway lesions. No consistent statistically significant differences between the two procedures were seen in the pulmonary functions or the range of individual patient variables. However, with an early tracheostomy, there was an eightfold greater incidence of contamination of the airway by new organisms, airway lesions were more frequent and severe, and the need for the tracheal tube was extended. To identify the epidemiologic variables and the pulmonary functions that discriminate between patients with serious airway lesions and those with mild lesions, and to evaluate the ability of these variables to differentiate the patients who died from those who survived, the distribution of all factors was compared in the two categories. The epidemiologic variables separated the patients according to their airway lesions only, while the difference in pulmonary functions was statistically significant only between the patients who died and those who survived.

Acute Disease↗