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Biomedical subjects

P Vock

Publications and source records attributed to P Vock.

At least 109 records · Page 6Linked to original sources
PubMed1986

Cardiophrenic angle adenopathy: update of causes and significance.

Of 21 cases of cardiophrenic angle adenopathy (CAA) detected on computed tomography (CT) examination, 12 were due to malignant lymphomas, seven to carcinomas, and two to mesotheliomas. Of the nine lesions that were not malignant lymphomas, four were of supradiaphragmatic and five of infradiaphragmatic origin. On average, CAA was detected 4.6 years after the primary neoplasm was diagnosed. Only 29% of the patients were alive 14 months after CAA was detected on CT scans. Radiography was inferior to CT in the detection of CAA, with only 35% of radiography results clearly positive. Malignant lymphoma is a major but not exclusive cause of CAA, and it must be differentiated from lymphatic seeding of supradiaphragmatic and infradiaphragmatic malignancies. Unilateral CAA may point to supradiaphragmatic neoplasms or, if right-sided, to ovarian carcinoma, and bilateral CAA may indicate another neoplasm of infradiaphragmatic origin.

Adult↗
PubMed1985

Combined use of magnetic resonance imaging (MRI) and spectroscopy (MRS) by whole body magnets in studying skeletal muscle morphology and metabolism.

As a pilot study, 31-P-spectra of the quadriceps femoris muscle (1.5T) and proton images of the right thigh (.5T) were performed in two cyclists (T) and two untrained (UT) subjects. During ischemia, while MRI did not show any change, phosphocreatine (PCr) concentration decreased and inorganic phosphate (Pi) increased. Recovery occurred within 3 minutes. Ergometric bicycle tests were performed outside the magnet. Submaximal workload (UT 150W/T 260W, 3.5 minutes) caused transient minimal changes in phosphorus metabolites. Supramaximal, partially anaerobic exercise (UT 320W/T 350W, 3.5 minutes) induced similar changes in heart rate, oxygen uptake rate, and plasma lactate in both groups. Decrease of the PCr/Pi ratio, however, was more pronounced in UT subjects and clearly lasted longer. If methodical problems can be resolved, combined MRS and MRI in whole body magnets may become a standard noninvasive modality, adding unique information on morphology (organ volume) and local metabolism to classic mechanical and global physiologic data.

Adult↗
PubMed1985

Endurance training in humans: aerobic capacity and structure of skeletal muscle.

The adaptation of muscle structure, power output, and mass-specific rate of maximal O2 consumption (VO2max/Mb) with endurance training on bicycle ergometers was studied for five male and five female subjects. Biopsies of vastus lateralis muscle and VO2max determinations were made at the start and end of 6 wk of training. The power output maintained on the ergometer daily for 30 min was adjusted to achieve a heart rate exceeding 85% of the maximum for two-thirds of the training session. It is proposed that the observed preferential proliferation of subsarcolemmal vs. interfibrillar mitochondria and the increase in intracellular lipid deposits are two possible mechanisms by which muscle cells adapt to an increased use of fat as a fuel. The relative increase of VO2max/Mb (14%) with training was found to be smaller by more than twofold than the relative increase in maximal maintained power (33%) and the relative change in the volume density of total mitochondria (+40%). However, the calculated VO2 required at an efficiency of 0.25 to produce the observed mass-specific increase in maximal maintained power matched the actual increase in VO2max/Mb (8.0 and 6.5 ml O2 X min-1 X kg-1, respectively). These results indicate that despite disparate relative changes the absolute change in aerobic capacity at the local level (maintained power) can account for the increase in aerobic capacity observed at the general level (VO2max).

Adipose Tissue↗
PubMed1984

Appearance of gas-containing gallstones on sonography and computed tomography.

The diagnostic features of gas-containing gallstones on sonography and CT in 6 patients and the in vitro findings in 30 gas-containing gallstones are analyzed. On plain abdominal radiography, the stellate appearance of gas collections, though infrequent, is quite characteristic. On real-time sonography, gas-containing calculi can be observed to float within bile. Furthermore, larger gas collections within gallstones can be identified since they produce high-level echoes in the acoustic shadow of the stone, probably due to sound reverberation. These phenomena, although interesting, do not interfere with the high accuracy of sonography in the detection of gallstones. CT detects gallstones when their density differs from that of bile. Due to high-density resolution, even minute gas collections are displayed and can reveal gallstones with an isodense matrix. However, under routine abdominal scanning conditions (8 mm collimation), the gas collections often appear round or ovoid, because spatial resolution is inferior to that on plain radiography. This fact should be considered in the differential diagnosis of gas collections in the gallbladder region found on CT.

Adult↗
PubMed1984

CT assessment of the adult intrathoracic cross section of the trachea.

After phantom validation of the method, normal tracheal morphology of 25 women and 25 men was studied retrospectively at level 1, the thoracic inlet; level 2, the supracarinal level, and level 3, halfway between. In no case was the minimal cross-sectional area less than 68% of the maximum of the three levels. Areas at the same level were different depending on sex, but not on other body parameters, and so were the means of the three levels: 194 mm2 (SD 35) in women and 272 mm2 (SD 33) in men. Mean tracheal area correlated with mean tracheal diameter (r = 0.98). Average configuration of the trachea was sagittal at the thoracic inlet and transverse supracarinally. Absolute tracheal cross sections of less than 120 mm2 in women and 190 mm2 in men and relative values of less than two-thirds compared with other levels should suggest an abnormality. Although static and not in competition with functional tests, noninvasive CT area calculation may be useful in demonstrating and quantifying tracheal obstruction when mediastinal neoplasms are staged or as a complementary morphological test when ventilatory studies do not afford enough information to localize the lesion and to decide about treatment.

Adult↗
PubMed1984

CT identification of bronchopulmonary segments: 50 normal subjects.

A systematic evaluation of the fissures, segmental bronchi and arteries, bronchopulmonary segments, and peripheral pulmonary parenchyma was made from computed tomographic (CT) scans of 50 patients with normal chest radiographs. Seventy percent of the segmental bronchi and 76% of the segmental arteries were identified. Arteries could be traced to their sixth- and seventh-order branches; their orientation to the plane of the CT section allowed gross identification and localization of bronchopulmonary segments.

Adolescent↗
PubMed1983

Measurement of liver volume by ultrasound and computed tomography.

A morphometric method to calculate liver volumes from transverse sections is evaluated (point-integrating method). In the first part of the study, 10 liver specimens were investigated by computed tomography (CT) and ultrasound (US); the calculated volumes were compared to the volumes obtained by water displacement of the organs. While CT showed an ideal agreement (r = 0.994), volumes calculated from US sections correlated less well (percentage differences from +12.5% to -9%, r = 0.915). In the second part of the study, the livers of 10 randomly selected patients were investigated by CT and US. Liver volumes were calculated using the point-integration method. Compared to the CT examination, US results show a good correlation with a correlation coefficient of r = 0.977. The point-integration method is very valuable to measure organ volumes from transverse sections. The method can be applied "offline" to photographic films, data do not have to be recorded electronically. The time required to calculate the volume of an organ is comparable to other methods.

Humans↗
PubMed1983

Peripheral middle lobe syndrome.

Classically, the middle lobe syndrome has been described as being caused by a central obstruction. Clinical records and radiologic findings were reviewed in 129 patients examined between 1955-1981 who had chronic disease in the right middle lobe and/or lingula. Fifty-eight patients (45%) had no evidence of a central obstructive lesion. The majority were middle-aged women with histories of chronic cough and chest pain. Bronchoscopic and radiologic evaluation served to exclude central lesions. Surgical confirmation was available in 38 patients. Pathologic study showed varying degrees of chronic inflammation, pneumonia, and bronchiectasis. Surgical results were excellent in isolated disease. Chronic atelectasis and pneumonitis of the right middle lobe and/or lingula do not always imply central obstruction. A lack of collateral ventilation is a plausible theory to explain the pathophysiology in such patients.

Bronchiectasis↗
PubMed1983

Tracheal cross-sectional area in children: CT determination.

A computer method that calculates tracheal cross-sectional area by compensating for partial volume averaging was developed and validated in a study with phantoms. The program was then used to determine the tracheal cross-sectional area of 30 normal children who ranged in age from four months to 18 years. CT-derived cross sections were correlated with age, height, weight, and body-surface area, and they were compared with findings of published clinical and post-mortem studies. CT cross-sectional areas ranged from 20-275 mm2, varied by as much as 22% at the three different tracheal levels studied, and appeared to correlate most closely with body height. CT-derived tracheal cross-sectional areas are quite similar to those in published reports of postmortem and clinical studies. Measurement of tracheal cross section by CT may prove useful in quantitating tracheal compromise by intrinsic or extrinsic causes.

Adolescent↗
PubMed1983

CT of the pulmonary ligament.

Most computed tomographic (CT) scans of the chest show the inferior pulmonary ligament and an associated septum in the lower lobe, although CT descriptions of these structures have not been reported. Conventional radiography of the ligament has relied on indirect signs: the position of the lower lobe in the presence of pneumothorax or pleural effusion, soft-tissue peaks along the upper surface of the diaphragm, and the rare traumatic paramediastinal pneumatocele (attributed to air in the ligament). CT clarifies the anatomic relations of the ligament and alterations caused by pleural effusion and pneumothorax. The ligament is probably responsible for some long linear shadows at the lung bases, and CT helps to distinguish these from scars, walls of bullae, and normal structures such as the phrenic nerve and the interlobar fissures.

Cystic Fibrosis↗
PubMed1983

Tracheal compression by mediastinal masses in children: CT evaluation.

Chest computed tomography (CT) was valuable in detecting extrinsic tracheal compression by mediastinal masses in two pediatric patients. This prompted an independent evaluation by CT of 14 children with masses involving the middle mediastinum and possible intrathoracic tracheal narrowing. Computer programs permit precise calculation of tracheal cross-sectional areas. Any apparent decrease in tracheal area may be compared with CT-derived data in normal children. Chest CT not only demonstrates the presence of extrinsic airway compression in pediatric patients with mediastinal masses, but also is capable of precisely measuring the extent of this narrowing. This method identifies children at potential risk for respiratory compromise and may aid in subsequent therapy.

Adolescent↗
PubMed1983

Computed tomography of the lung. Densitometric studies.

This discussion summarizes the physical basis for CT densitometry, the methods used for extracting density information from CT scans, and how the CT scanner has been used to noninvasively monitor the changes in the major mass and volume components that determine lung density (gas, vascular, and extravascular volumes).

Absorptiometry, Photon↗
PubMed1982

[The problem of metal clip artefacts in computerized tomography].

Ligature clips have proved to exhibit increasing radiodensity from titanium up to silver, steel and tantalum, according to the atomic number. clips of titanium, steel and tantalum attached to the patient's abdominal wall confirmed these findings in a plain film (n = 5), a digital scout view (n = 10) and a transverse CT scan (n = 10). The extent of the radial artefacts caused by the clips is directly related to their imaged intensity, being high for tantalum and low for steel and titanium. Because of the poor visualization of the titanium clips on the plain film, the authors recommend steel clips for the clinical test which appears to be necessary in view of the possible concomitant artefacts that could appear due to vascular pulsation.

Silver↗
PubMed1982

Computed tomography in staging of carcinoma of the urinary bladder.

Seventy-seven patients with carcinoma of the urinary bladder were investigated by computed tomography (CT) and the results compared with those of pathological staging. The overall accuracy rate was 81% for the estimation of local tumour extension. Perivesical tumour extension was overestimated by CT owing to previous bladder surgery or radiotherapy in about half of the cases. Nevertheless, CT gives unrivalled diagnostic information in advanced tumour invasion. The diagnostic accuracy rate of CT in the detection of lymph node metastases was 89%, compared with 73% for lymphography.

Adult↗
PubMed1982

Computed tomography of the normal and pathological thoracic inlet.

The thoracic inlet is insufficiently investigated by conventional radiographic techniques. CT clearly demonstrates this area free of superimposition. Thorough knowledge of cross sectional anatomy is essential for CT interpretation. There is a wide spectrum of pathology involving the thoracic inlet because its visceral, lymphatic, vascular and nervous structures are connected with many parts of the body. An overview is given on the indispensable role of CT in the investigation of the various pathological entities involving the thoracic inlet.

Evaluation Studies as Topic↗