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Biomedical subjects

H D Royal

Publications and source records attributed to H D Royal.

At least 73 records · Page 4Linked to original sources
PubMed1985

Cerebrospinal fluid anion transport: studies of pertechnetate in unanesthetized sheep.

Perfusion of the ventriculocisternal system in unanesthetized sheep was used to quantify the pathways by which the pertechnetate anion (TcO4-) may leave the cerebrospinal fluid space. The largest fraction (about 89%) was removed from the fluid before it reached the cisterna magna; this extraction was significantly inhibited by iodide ion in the perfusion fluid. One-fifth of the extracted pertechnetate remained in the head of the animal for over 3 hours. Only about 3% of the infused pertechnetate was resorbed with the bulk flow of cerebrospinal fluid through the arachnoid villi. These results are consistent with the concept of a specific brain channel for removal of anions. As pertechnetate and iodide ion are thought to be transported by the same mechanisms, the physiological role of this channel may be maintenance of a very low iodide concentration in the extracellular fluid of the brain.

Animals↗
PubMed1984

Cerebral perfusion imaging with iodine 123-labeled amines.

Two amines, N-isopropyl p-iodoamphetamine and N,N,N'-trimethyl-N'-[2-hydroxyl-3-methyl-5-iodobenzyl]-1,3-prop anediamine, have been labeled with iodine 123. The brain uptake of these radioactive tracers is proportional to cerebral blood flow. These tracers are retained in the brain for a sufficiently long time so that imaging can be performed with standard, readily available instrumentation. Transaxial tomography with amines is useful in acute cerebral infarction, in which the x-ray computed tomographic scan may be normal for several days after onset of symptoms while the uptake of radioisotope-labeled amines will be altered immediately after the onset of the stroke. It is also useful in examining patients with cerebral vascular disease and in the preoperative examination of patients with partial epilepsy.

Amines↗
PubMed1984

Radionuclide plethysmography and Tc-99m red blood cell venography in venous thrombosis: comparison with contrast venography.

Radionuclide plethysmography (RPG) is a new technique that uses Tc-99m labelled red blood cells to ascertain changes in venous volumes by detecting the change in counts in response to the inflation and deflation of proximal thigh cuffs. Diagnosis of ileofemoral venous occlusion is possible using this technique, which also provides kinetic data of venous outflow. A range of normal values was defined in 19 subjects for per cent change in venous capacitance and venous outflow. Twenty-one patients with suspected deep venous thrombosis were studied prospectively using RPG, radionuclide venography (RV), and contrast venography (CV) to establish the usefulness of RPG alone and in combination with RV in the diagnosis of deep venous thrombosis. RPG proved to be a reliable technique for the diagnosis of ileofemoral venous thrombosis (sensitivity, 91%; specificity, 100%). RV was less sensitive (73%) and less specific (93%) in diagnosing that condition. When RPG is used as the criterion for the detection of ileofemoral vein thrombosis and RV is used as the criterion for the detection of calf vein thrombosis, the combined techniques show improved sensitivity (92%) and specificity (93%) for the detection of all deep venous thromboses.

Adult↗
PubMed1984

Thallium-201 myocardial imaging in patients on chronic hemodialysis.

10 long-term hemodialysis patients had immediate and redistribution thallium-201 myocardial imaging performed after a course of hemodialysis. Subjects had EKGs done on the same day before and after dialysis. 3 of the 10 subjects had resting thallium-201 myocardial imaging obtained on non-dialysis days. 60% of the electrocardiograms showed changes with dialysis. All 13 thallium studies were abnormal, showing multiple transient filling defects at rest. Most subjects had permanent filling defects as well. It is concluded that hemodialysis patients have a high frequency of abnormal thallium-201 myocardial images at rest. The cause of these abnormal studies is uncertain.

Adult↗
PubMed1984

Instantaneous measurement of left and right ventricular stroke volume and pressure-volume relationships with an impedance catheter.

The feasibility of using continuous on-line recording of intraventricular electrical impedance to measure ventricular stroke volume was assessed in 12 patients at cardiac catheterization with a multielectrode impedance catheter and a 1.3 kHz measuring current of 4 microA. Stroke volumes determined by electrical impedance were compared with stroke volumes determined by the thermodilution technique in 10 patients and correlated with an r value of .95. Directional changes in impedance recordings throughout the cardiac cycle were also compared with volume curves obtained from six patients by radionuclide ventriculography, and in all instances the agreement between the two volume recordings was excellent. For all patients, on-line measurements of impedance showed a beat-by-beat decrease in stroke volume with the Valsalva maneuver and the administration of amyl nitrite, as well as an immediate increase in stroke volume in the contraction following an extra-systolic beat. Similar directional changes in stroke volume were recorded in both left and right ventricles. Left ventricular pressure-volume relationships were assessed with simultaneous left ventricular pressure recordings and volume signals recorded from the impedance catheter to determine if impedance measurements of volume can be used clinically. Pressure-volume diagrams were subsequently plotted, and for all patients these diagrams showed characteristic isovolumetric contraction and relaxation phases as well as typical ejection and filling periods. Moreover, beat-by-beat sequential pressure-volume diagrams constructed for patients during the administration of amyl nitrite revealed a linear end-systolic pressure-volume relationship.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1984

Improvement in indexes of diastolic performance in patients with congestive heart failure treated with milrinone.

To elucidate the mechanisms by which the new bipyridine inotropic agent milrinone improves cardiac function, we examined multiple indexes of left ventricular diastolic function before and after administration of milrinone to patients with advanced (NYHA class III or IV) congestive heart failure. In 13 patients left ventricular pressure measurements were made with a micromanometer to permit assessment of peak negative dP/dt and the time constant of left ventricular isovolumic relaxation, T, before and after milrinone. In nine patients radionuclide ventriculographic studies were performed during left heart catheterization, allowing calculation of left ventricular peak filling rate, volumes, and the diastolic pressure-volume relationship before and after milrinone. After intravenous administration of milrinone, peak negative dP/dt increased (+ 18%; p less than .01) and T decreased (-30%; p less than .01), while heart rate increased by only 8% (87 +/- 12 to 94 +/- 15 beats/min; p less than .01), left ventricular systolic pressure did not change, and mean aortic pressure fell by 11% (p less than .01). Left ventricular peak filling rate increased (1.2 +/- 0.6 to 1.7 +/- 0.7 end-diastolic volumes/sec; p less than or equal to .02) despite a decrease in left ventricular filling pressure (mean pulmonary wedge pressure 27 +/- 7 to 18 +/- 9 mm Hg; p less than .01). There was a fall in left ventricular end-diastolic pressure (28.6 +/- 6 to 19 +/- 7 mm Hg; p less than or equal to .01), with no significant change in left ventricular end-diastolic volume. This was associated with a downward shift in the left ventricular diastolic pressure-volume relationship in most cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Predictive value of perfusion defect size using N-isopropyl-(I-123)-p-iodoamphetamine emission tomography in acute stroke.

Sixteen patients with acute cerebral infarction who were studied with N-isopropyl-I-123-p-iodoamphetamine (IMP) brain scans were followed to determine if the extent of perfusion abnormality was predictive of the clinical course. Lesion size and diminished density on the scans appeared to correlate well with presenting symptoms, but were not predictive of outcome. When evaluated by IMP scanning in conjunction with computerized tomography, however, a group of patients could be identified in whom therapy may improve prognosis.

Acute Disease↗
PubMed1983

Single-photon emission computed tomography. A method of measuring cerebral blood flow in three dimensions (preliminary results of studies in patients with epilepsy and stroke).

The recent development of single-photon emitting radiopharmaceuticals that reflect cerebral blood flow has introduced a new era for the useful application of nuclear medicine to the investigation of neurological disease. Using 123I labelled N-isopropyl-p-iodoamphetamine, we have performed emission-computed tomographic scans of the brain in several clinical settings. These studies display cross-sectional maps of cerebral blood flow and promise significant clinical utility in a variety of brain diseases. In the eight patients with epilepsy, the scans showed good localization of the abnormal foci, and correlated well with the findings at operation in the five patients who were submitted to surgery. All 10 patients with stroke had abnormal scans, and the abnormalities in cerebral blood flow were frequently more extensive than the lesions seen on the transmission-computed tomographic scan. This initial experience leads us to anticipate an increasing role in clinical neurology for single-photon emission computed tomographic scans of cerebral blood flow.

Adolescent↗
PubMed1983

Detection of bleeding from angiodysplasia of the jejunum by blood pool scintigraphy.

Bleeding from angiodysplasia of the gastrointestinal tract has become widely recognized. In most patients there is a single focal lesion in the colon. Small bowel involvement is rare and usually associated with colonic lesions. There have been no reports of bleeding angiodysplasia affecting the small bowel only. We were able to detect bleeding from an isolated angiodysplasia of the jejunum and correctly localize it. Our diagnosis was greatly aided by the use of dynamic data collection and by the cinematic display of the data.

Aged↗
PubMed1983

An all-digital nuclear medicine department.

An all-digital nuclear medicine department is described. Nuclear medicine images are acquired by a separate computer interfaced to each camera. The digital images are viewed, manipulated, and interpreted from remote display stations in an interpretation area. The interpretation is dictated into a Rapid Telephone Access System (RTAS), where the voice is digitized and stored. By dialing the patient's identification number, the referring physician can hear the interpretation over any telephone. The images are filed on large storage discs. The digital scans can be rapidly and easily accessed for later review by the use of several directory programs. This system has brought not only efficiency and cost savings, but the ability for remote viewing elsewhere in the hospital and telephone transmission of nuclear cardiology studies from community hospitals for interpretation in the digital nuclear medicine department.

Computers↗
PubMed1983

Telephone transfer of nuclear cardiology studies.

Data of nuclear cardiology studies are acquired on a computer and transmitted by telephone from a community hospital to a computer at a teaching hospital for analysis. Interpretations of the studies are dictated into a RTAS radiology reporting system. The referring physician and transcriptionists from the sending hospital may hear the interpretations by calling into RTAS on the same day as the studies were performed.

Diagnosis, Computer-Assisted↗
PubMed1983

Cost effectiveness of the all-digital nuclear medicine department.

The costs of an all-digital nuclear medicine department are compared to a nuclear medicine department using and storing conventional photographic images. The digital format results in a savings of $1.27 per study or an annual savings of $7,620.00 for a department which does 6,000 examinations each year.

Computers↗
PubMed1982

An evaluation of 99mTc-labeled red blood cell scintigraphy for the detection and localization of gastrointestinal bleeding sites.

99mTechnetium-labeled red blood cell scintigraphy was performed upon 39 patients with clinical evidence for acute lower gastrointestinal bleeding from an unknown source. Seventeen of 39 patients (44%) had a scan became positive 6 or more h after injection, consistent with intermittent bleeding, in 8 of 17 patients (47%). In the 11 patients in whom the bleeding site was definitely identified by arteriography, surgery, or colonoscopy, scintigraphy correctly localized the bleeding site in 10 of 11 patients (91%). Four of 11 patients (36%) had an active bleeding site identified by arteriography. Ten of 17 patients (58%) with a positive scan required either gelfoam embolization (4 patients) or surgery (6 patients) to control the bleeding, whereas only 1 of 22 patients (5%) required surgery when the scan was negative. Six deaths occurred in the scan-positive patients compared with no deaths in the scan-negative patients. None of the 8 patients who had arteriography and no active bleeding site by scintigraphy had arteriographically demonstrable active bleeding. Scintigraphy provides a reliable noninvasive test to screen patients in whom arteriography is being considered to localize active bleeding sites. If the arteriogram is negative, the scintigraphic findings alone may guide the surgical or arteriographic intervention. In addition, scintigraphy identifies two patient populations which have considerably different morbidity and mortality.

Adult↗
PubMed1981

Scintigraphy of hepatic hemangiomas: the value of Tc-99m-labeled red blood cells: concise communication.

Fourteen patients with hepatic hemangiomas were evaluated by Tc-99m colloid scintigraphy and Tc-99m RBC angiography, including flow studies and early and delayed static studies. On colloid scintigraphy, the liver appeared enlarged, with single or multiple focal defects. During the flow and early static Tc-99m RBC studies, the lesions showed poor perfusion and were filled only partially or not at all. Delayed Tc-99m RBC studies demonstrated the whole extent of the lesion and all the lesions when multiple hemangiomas were present. A flow study showing decreased perfusion and a late blood-pool study showing increased local blood volume appear characteristic of hemangiomas. Liver biopsy should not be attempted in such cases.

Angiography↗