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Biomedical subjects

A Alavi

Publications and source records attributed to A Alavi.

At least 397 records · Page 22Linked to original sources
PubMed1978

Local cerebral blood volume response to carbon dioxide in man.

We used an emission tomographic brain scanner to investigate the relationship between local cerebral blood volume (LCBV) and arterial blood carbon dioxide tension (PaCO2) in normal awake man. Measurements were made separately in three dimensions in various regions of grey and white matter, and the resting LCBV as well as the difference in sensitivity among these regions were compared. Over the range of PaCO2 studied (20-42 torr), the response of both the grey matter and the white matter to carbon dioxide was linear. The LCBV sensitivity of the grey matter to changes in PaCO2 was 0.053 ml/100 g per torr PaCO2 and in the white matter this sensitivity was 0.046 ml/100 g per torr PaCO2. These sensitivities were found not to be significantly different, yielding a slope of 0.049 ml/100 g per torr PaCO2 for the LCBV-PaCO2 curve for the entire brain. This is in excellent agreement with the other data for the whole brain. The resting cerebral blood volume of the grey matter at a PaCO2 of 34.4 torr, which was the average resting arterial carbon dioxide tension of the subjects, was 5.0 ml/100 g and was significantly higher than for white matter, which was 3.6 ml/100 g. At the local level, the cerebral blood volume of the frontal cortex is significantly less than that of the thalamus, whereas the frontoparietal cortex in the region of the sylvian fissure has a local cerebral blood volume significantly greater than that of the thalamus.

Adolescent↗
PubMed1978

Hepatic hemangiomas: pitfalls in scintigraphic detection.

The evaluation of solitary hepatic lesions detected on scintiscans is a common clinical problem. It is usually assumed that radionuclide rapid sequence flow studies and blood pool images are reliable and accurate methods of demonstrating the vascularity of hepatic lesions. Our recent experience with 3 patients with angiographically proven hepatic hemangiomas indicates that radionuclide techniques may fail to detect the vascularity of hemangiomas. We speculate that blood flow within a hepatic hemangioma may be sluggish and its vascularity may be appreciated only by arteriography. Therefore, we alert the clinician to assess the vascularity of solitary hepatic tumors by angiography before percutaneous liver biopsy and thereby avert the possibility of life-threatening exsanguination, as occurred in one of our patients.

Adult↗
PubMed1978

Technetium-99m stannous phytate as an imaging agent for lymph nodes.

This report describes preliminary results using technetium-99m stannous phytate as a lymph-node imaging agent in animals. After the subcutaneous administration there is good visualization of the draining nodes, best obtained 2-4 hr from the time of injection. There is also visualization of the liver, spleen, kidneys, and bladder. This agent appears suitable for lymph-node imaging in areas where the extranodal concentration does not interfere.

Animals↗
PubMed1977

Chronic synovitis with early cartilage destruction in sickle cell disease.

Two patients with sickle cell disease presented with joint pain and early x-ray evidence of articular cartilage loss. Both later developed increasingly destructive arthritis with chronic synovitis identified in synovial biopsies. One patient developed demonstrable aseptic necrosis. Destructive arthropathy is much less common than the frequent transient effusions in sickle cell disease.

Adult↗
PubMed1977

Scintigraphic detection of acute gastrointestinal bleeding.

In induced bleeding experiments on dogs, 99mTc-sulfur colloid was a suitable agent for detecting the bleeding site in the small intestine, providing that the site was distant from the liver and spleen. Bleeding sites were detectable at rates as low as 0.1 ml/min. When induced in the sigmoid or descending colon, the site was demonstrated by scintigraphy with 99mTc-sulfur colloid. Unsatisfactory images were obtained in the esophagus and stomach, however, when 131I-ortho-iodohippurate or 99mTc-DTPA was used.

Animals↗
PubMed1977

Computed tomography of intracerebral hematomas. II. Radionuclide and transmission CT studies of the perihematoma region.

Transmission CT studies of 40 patients with intracerebral hematomas were used for an analysis of the perihematoma region. Nineteen of these patients had radionuclide studies. In the brain adjacent to an intracerebral hematoma, the patterns of pertechnetate uptake on scintillation scans and contrast enhancement on transmission CT resemble those observed in cerebral infarctions. The healing of the perihematoma region proceeds similarly to that of infarcts. The brain about the hematoma is ischemic tissue which behaves much like cerebral infarction not related to hematomas.

Adolescent↗
PubMed1977

Painful knees in older patients: radionuclide diagnosis of possible osteonecrosis with spontaneous resolution.

The syndrome of osteonecrosis of the femur at the knee presents as sudden onset of knee pain in elderly patients. It is classically associated with a subchondral radiolucency and a positive radionuclide bone scan. The lesion may progress to collapse of the bone. In this report, twelve cases are described in which the clinical entity of osteonecrosis of the femoral condyle was diagnosed because the patients had a clinical picture identical to that of osteonecrosis and also had positive bone scans. However, roentgenographic changes supposedly diagnostic of the condition were not seen. In twelve patients, arthrotomy was avoided. They became asymptomatic and their bone scans returned to normal in a few months.

Age Factors↗
PubMed1977

Early detction of avascular necrosis of the femoral head by 99m technetium diphosphonate bone scan: a preliminary report.

Since roentgenographic changes characteristic of avascular necrosis of the femoral head frequently do not appear for several months after onset of symptoms, it may be difficult to diagnose this condition in its early stages and then institute therapeutic measures designed to prevent collapse of the femoral head and to enhance repair. Bone scans made after intravenous injection of 99mTc DP revealed increased activity over the femoral head in 5 patients with avascular necrosis 2 to 5 months before changes appeared on conventional roentgenograms. Although increased activity at the site of the lesion is not specific for avascular necrosis, the correct diagnosis can usually be established by taking into account other clinical, roentegenographic, and laboratory findings. Bone scanning with 99mTc DP is safe, even for high-risk patients, and relatively simple to perform.

Adolescent↗
PubMed1976

Bone and marrow imaging in sickle cell disease: diagnosis of infarction.

Sickling of erythrocytes in patients with S-hemoglobin causes marrow and bone infarction. The former can be demonstrated as a lack of 99mTc-sulfur colloid uptake on marrow imaging examination. These defects may resolve or persist long after the acute episode. If the bone is involved in the acute episode, imaging within the first few days of onset of symptoms can show lack of 99mTc-labeled phosphate uptake, usually in a smaller area than that shown by marrow scanning. Follow-up bone imaging shows increased activity, particularly along the circumference of the bone where periosteal reaction can be demonstrated radiographically. Magnification by use of the pinhole collimator provides better definition of the uptake defect and the distribution of the increased reactive uptake. Timing of examination is important. If marrow imaging is performed in an asymptomatic period, the repeat examination during a painful crisis permits differentiation of old and acute marrow infarction. If 99mTc-phosphate imaging is performed after about 2 days of symptoms, acute infarction can be differentiated from osteomyelitis, which it may mimic clinically. Although osteomyelitis may cause no increased activity in the first 48 hr after onset of symptoms, it is characterized by intense focal activity thereafter (see article by Handmaker in this issue). To assist in differentiating bone infection in a site of marrow infarction demonstrated by marrow imaging, serial bone imaging with magnification may be useful. The uptake defect, followed in several days to 2 weeks, by circumferential increased activity, is a different pattern than the homogeneously intense activity of osteomyelitis, but the peripheral distribution may not be apparent on routine imaging. It is hoped that the utilization of these techniques can decrease the emotional and economic costs of prolonged hospitalization for suspected infection and can also expand our knowledge of the complex pathophysiologic changes of sickle cell bone disease.

Adult↗
PubMed1976

The Mark IV system for radionuclide computed tomography of the brain.

The Mark IV scanning system is a simple four-sided arrangement of 32 independent detectors which rotate continously as a unit, detecting, processing, and displaying the reconstructed data while the study progresses. Detection is by single photon counting and is compatible with commercially available radionuclides. An empirical correction is applied for attenuation, difference in detector response, and scatter. It is a high-sensitivity device with approximately uniform resolution throughout the section plane. There is good reproducibility and accuracy for absolute quantification of radionuclide concentration in the brain. Clinical applications include scans of 99mTcO4, 99mTc-RBC, 123I-iodoantipyrine, 99mTc-diphosphonate, and 111In-DTPA.

Adolescent↗
PubMed1976

Gallium-67 scans in children with solid tumors.

Twenty pediatric patients with malignant disease were studied by whole body gallium scans. Seven had Hodgkin's disease, five had soft tissue sarcomas, three had neuroblastomas, two had Wilm's tumors, and one each had a hepatoblastoma, embryonal cell carcinoma, and sacrococcygeal teratoma. Of 50 sites studied, there was a true positive result in 17%, and in 58% there were false negative results. The method served best in patients with Hodgkin's disease, where the true positive rate was 64%. In no instance did the gallium scan affect the clinical management of a patient.

Adolescent↗
PubMed1976

Calcified intraperitoneal metastases from ovarian carcinoma.

Three cases of calcified ovarian metastatic carcinoma are reported in order to illustrate their principal forms and distribution. These cases also demonstrate unusual features of serosal, colonic, and gastric invasion; ureteral obstruction by a calcified metastasis; and active uptake of technetium diphosphonate by the metastatic lesions. Plain films often simulate retained colonic barium.

Adult↗