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Biomedical subjects

N D Greyson

Publications and source records attributed to N D Greyson.

At least 19 recordsLinked to original sources
PubMed1992

Patients with symptomatic ischemia have larger thallium perfusion abnormalities and more adverse prognosis than patients with silent ischemia.

OBJECTIVE: To evaluate the mechanism for silent ischemia and the effect on prognosis. DESIGN: To test the hypothesis that patients with silent (compared with symptomatic) ischemia have less severe ischemia and a more favorable prognosis, the authors prospectively evaluated 152 consecutive patients with a positive exercise electrocardiogram with exercise thallium scintigraphy and followed them for two years. SETTING: Tertiary care university-based hospital. RESULTS: Asymptomatic patients during the exercise test had a greater exercise duration (9.4 +/- 3.1 versus 6.3 +/- 2.5 mins, P < 0.01), maximal heart rate (155 +/- 20 versus 136 +/- 20 beats/min, P < 0.01), systolic blood pressure (184 +/- 21 versus 176 +/- 23 mmHg, P < 0.05) and double product than patients who were symptomatic with chest pain. Although there was no difference in the magnitude of ST depression, time to ST depression was greater in the asymptomatic (5.6 +/- 2.7 mins), compared with symptomatic (4.6 +/- 2.6 mins), group (P < 0.01). Thallium ischemic score was smaller during asymptomatic ischemia (2.1 +/- 2.7) compared with symptomatic ischemia (3.9 +/- 3.1, P < 0.01). These findings were also demonstrated in a subgroup of 107 patients with both a positive exercise electrocardiogram and positive thallium scan. The patients with asymptomatic ischemia had a two-year cardiac event rate of 5.1% compared with 13.8% in the symptomatic patients (P = 0.065). CONCLUSIONS: Patients with asymptomatic ischemia have less severe myocardial ischemia and a better prognosis than patients with symptomatic myocardial ischemia during exercise testing.

Angina Pectoris↗
PubMed1991

A bullseye display of regional perfusion of the brain.

The authors submit a method of viewing Tc-99m HMPAO SPECT images of the brain based on the principles of the myocardial bullseye or polar mapping. Commercially available software for the production of a myocardial bullseye display is suitable for the preparation of a bullseye display of regional perfusion image of the brain. This display facilitates the detection of cerebral cortical perfusion defects by displaying all SPECT oblique slices concentrically from base to vertex in a single image.

Brain↗
PubMed1990

Long-term results of bipolar arthroplasty in osteoarthritis of the hip.

Bipolar arthroplasty of the hip was introduced by the first author in 1974. From that time until 1988, this type of arthroplasty has been carried out in 1213 hips at the authors' institution. Included is a group of 760 osteoarthritic hips on which follow-up studies have been done at six months, five years, ten years, and 15 years. Studies of the acetabulum show healthy bone preservation as long as 15 years after surgery. A process of floor reinforcement in certain states has also been identified. The relatively simple operative technique has resulted in few postoperative complications. Clinical results as long as 15 years postsurgery compare favorably with two-piece replacement techniques.

Acetabulum↗
PubMed1989

Role of resting thallium201 perfusion in predicting coronary anatomy, left ventricular wall motion, and hospital outcome in unstable angina pectoris.

We performed quantitative thallium scintigraphy in 66 unstable angina patients, 5.6 +/- 5.1 hours after rest pain, to predict coronary anatomy, left ventricular wall motion, and hospital outcome. Thallium defects and/or washout abnormalities were present in 5 of 10 (50%) patients with coronary stenoses less than 50%, 27 of 33 (82%) patients with coronary stenosis greater than or equal to 50% and no history of previous myocardial infarction, and in 23 of 23 patients (100%) with histories of previous infarction. Defects were uncommon in the territory of vessels with less than 50% (13 of 61, 21%), but significantly more common in the territory of vessels with greater than or equal to 50% stenosis (57 of 137, 42%), p less than 0.005. With the addition of washout abnormalities to defect analysis, sensitivity for detection of coronary stenoses improved to 67% (92 of 137), p less than or equal to 0.005, but specificity fell to 59% (36 of 61), p less than 0.01. Segmental wall motion abnormalities were less common in segments with normal perfusion (21%) or in those with washout abnormalities alone (19%), than in segments with thallium defects (45%, p less than 0.005). Defects in patients with previous infarction were common in both segments, with normal (26 of 66, 40%) or abnormal (24 of 45, 53%) wall motion. Eleven of 18 patients with in-hospital cardiac events, but no history of myocardial infarction, had resting thallium defects, whereas only 8 of 25 patients without cardiac event had thallium defect (p = 0.056).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Clinical and laboratory features of acute sulfur dioxide inhalation poisoning: two-year follow-up.

We present clinical and laboratory results (including nuclear imaging) obtained over a period of two years in two nonsmoking miners who were exposed to high concentrations of sulfur dioxide (SO2) after a mine explosion. Within 3 wk of the accident, both miners had evidence of severe airways obstruction, hypoxemia, markedly reduced exercise tolerance, ventilation-perfusion mismatch, and evidence of active inflammation as documented by positive gallium lung scan. Serial ventilation-perfusion scans over the first 12 months showed progressive improvement without returning to normal. After the initial recovery, there has been no significant change over the subsequent two years postinjury. Pulmonary function and exercise tests also displayed a similar pattern of initial improvement. We conclude that (1) acute exposure to high concentrations of SO2 results in severe airways obstruction, (2) pulmonary function abnormalities are partially reversible, and (3) most of the improvement occurs within 12 months after the initial injury.

Accidents, Occupational↗
PubMed1989

"Kirlian photography" film artifacts.

A film artifact due to static discharges from the fingers is described. These are similar to Kirlian photographs, ostensibly representing the radiant spiritual aura.

Diagnostic Imaging↗
PubMed1987

Cardiovascular effects of positive pressure ventilation in humans.

Pulsus paradoxus is the pathological exaggeration of the normal transient decrease in arterial blood pressure that occurs during spontaneous inspiration. The transient increase in arterial pressure associated with positive pressure inspiration is termed reversed pulsus paradoxus (RPP). Cardiorespiratory interactions and the mechanism of these effects have been studied extensively in animals, and to a lesser extent, in humans. In this clinical investigation pulsus paradoxus and RPP were studied in 10 postoperative cardiac patients with invasive monitoring and mediastinal pressure catheters placed intraoperatively. From end-expiration to end-inspiration, RPP was accompanied by decreased transmural pressures in the right atrium, left atrium, and aorta. Left ventricular end-systolic volume measured by radionuclide studies diminished during a positive pressure inspiration, without a significant change in end-diastolic volume. These results are consistent with decreased left ventricular afterload as the major mechanism of RPP. During spontaneous breathing, inspiration was associated with converse effects, a fall in arterial pressure and an increase in transmural right atrial, left atrial, and aortic pressures from end-expiration to end-inspiration. End-systolic volume was significantly larger at end-expiration than end-inspiration, with no change in end-diastolic volume. These findings suggest that an increase in left ventricular afterload during inspiration is responsible for the observed pulsus paradoxus.

Blood Pressure↗
PubMed1987

Acute unilateral pulmonary nonventilation due to mucous plugs.

Acute bronchial obstruction by mucous plugs may be manifested clinically by dyspnea, hypoxemia, and respiratory alkalosis mimicking pulmonary thromboembolism. In eight cases with complete interruption of ventilation to an entire lung, chest radiography failed to reveal the extent of the obstruction. Perfusion was substantially less affected than ventilation. Routine ventilation-perfusion scintigraphy with technetium-99m DTPA aerosol aids in the diagnosis of acute major bronchial obstruction in patients with suspected pulmonary thromboembolism.

Acute Disease↗
PubMed1984

The clinical significance of radionuclide bone and gallium scanning in osteomyelitis of the head and neck.

Osteomyelitis of the head and neck remains a difficult clinical problem both in diagnosis and treatment evaluation. The purpose of this manuscript is to review our clinical experience with 25 cases of osteomyelitis distributed evenly among the temporal bone and skull base, the paranasal sinuses, and the mandible. Radionuclide bone and gallium scan images accurately depicted the biologic activity of the disease process and permitted accurate treatment evaluation and patient monitoring. This work demonstrates the potentials and limitations of radionuclide imaging with bone and gallium scan agents and attempts to define a role for their contemporary use in the management of osteomyelitis of the head and neck.

Adult↗
PubMed1984

Reflex sympathetic dystrophy in hemiplegia.

Eighty-five consecutive post-CVA hemiplegic patients were assessed prospectively for radionuclide and clinical features of reflex sympathetic dystrophy (RSD). Scintigraphy, a safe and relatively noninvasive procedure, has proved to be more sensitive than clinical evaluation for early diagnosis of RSD. RSD was found to be more prevalent in the post-CVA hemiplegic patient than previously reported. Twenty-one patients (25%) exhibited radionuclide evidence of RSD based on delayed scan criteria of increased uptake in the hemiplegic wrist, metacarpal-phalangeal (MCP) and interphalangeal (IP) joints. Two patterns of soft tissue blood flow were observed. Eight scan-positive RSD patients presented a low flow pattern identical to the non-RSD hemiplegic patients while the remaining thirteen exhibited a high flow pattern. Neither demographic characteristics, co-morbid conditions, etiology of CVA, nor site of lesion had any bearing on RSD development. There was no clinical or radionuclide evidence of bilateral involvement commonly described in other heterogeneous RSD populations. Clinical diagnosis was difficult, as various features of the syndrome were often present for other reasons and the presentation was frequently incomplete. MCP tenderness to compression proved to be the most valuable clinical sign of RSD, with a predictive value, sensitivity, and specificity rates of 100%, 85.7%, and 100% respectively.

Age Factors↗
PubMed1984

Three-phase bone studies in hemiplegia with reflex sympathetic dystrophy and the effect of disuse.

Eighty-five patients with cerebral vascular accidents were assessed with three-phase bone scintigraphy of the hands and with whole-body delayed bone imaging. Nine patients (10%) had normal three-phase bone images. Fifty-five patients (65%) showed decreased blood flow and blood-pool images of the hands and wrists with normal delayed bone scintigrams, indicating the effect of paralysis or disuse. Twenty-one patients (25%) had diffuse increased uptake with periarticular accentuation, felt to be bone-scintigraphic evidence of reflex sympathetic dystrophy of the hands and wrists; in two patients this occurred before its clinical appearance. Thirteen of the 21 reflex sympathetic dystrophy syndromes (RDS)-involved limbs (62%) had increased blood flow, whereas 8 (38%) had decreased flow. Gross limb blood flow appears to be related to the degree of muscle activity, but flow may be altered by the presence of sympathetic changes. A possible dissociation between whole-limb flow and bone blood flow in paralyzed limbs involved with RDS is discussed. The elbow was involved in only one case, and a true "shoulder-hand" distribution was seen in only 11 of 21 cases (52%). Five patients (6%) had leg involvement on whole-body imaging. Traumatic synovitis of the wrist, and trauma to subluxed shoulders, could be recognized on the delayed study.

Adult↗
PubMed1983

Thyroid tumor imaging.

Clinical assessment of a patient with a focal or diffuse thyroid tumor is but the first step in diagnostic evaluation. The diagnostic imaging process augments information obtained by the inspecting eye and the palpating hand; it allows the qualification (for example, cystic v solid) and the quantification (for example, size, extension, and assessment of physiologic function) of the thyroid tumor mass. This diagnostic input allows the establishment of a more realistic provisional diagnosis and directs a rational treatment approach to the patient. This presentation reviews the major imaging modalities available for thyroid tumor evaluation: diagnostic ultrasound, radionuclide scans, and conventional radiology and computed tomography. The applications of these various modalities and their critical potentials and limitations are placed in a contemporary clinical setting. It is hoped that an increasing familiarity with these imaging modalities will give better direction to the specialist in otolaryngology--head and neck surgery and greater surgical benefit to his or her patients.

Adenocarcinoma↗
PubMed1983

Predicting nodal metastases in breast cancer by lymphoscintigraphy.

In a prospective trial, 89 women with breast lumps underwent bilateral axillary and internal mammary lymphoscintigraphy preoperatively, using technetium-99m antimony sulfide colloid. All scans were interpreted blindly by three separate observers. Breast biopsy was then performed; if the biopsy specimen showed malignant tumour, definitive therapy was performed with axillary dissection. The interpretation of the axillary and internal mammary lymphoscintigrams was subsequently compared with the histologic assessment of the axillary nodes. Of the 89 women, 54 had benign disease and 35 had cancer. The internal mammary lymphoscintigram was considered to show abnormality in only 1 of the 54 patients with benign disease. One patient with cancer was eliminated from the review. Sixteen of the remaining 34 patients had axillary node metastases. Of these, 8 had an abnormal internal mammary lymphoscintigram. Only 2 of the 18 patients with cancer but no axillary metastases had an abnormal internal mammary lymphoscintigram. One bilateral axillary lymphoscintigram in the 54 patients with benign disease was discarded for technical reasons. The axillary lymphoscintigram was accurate in 52 of the remaining 53 patients. Two such scintigrams in the 35 patients with breast cancer were discarded for technical reasons. The axillary lymphoscintigram indicated abnormalities in 12 of 16 patients with axillary nodal metastases but appeared normal in 13 of 17 patients without axillary metastases. Lymphoscintigraphy may play a valuable role in the staging of breast cancer in the future.

Antimony↗