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Biomedical subjects

G F Gates

Publications and source records attributed to G F Gates.

At least 19 recordsLinked to original sources
PubMed1996

Oblique angle bone SPECT imaging of the lumbar spine, pelvis, and hips. An anatomic study.

Bone SPECT offers advantages over planar imaging in detecting skeletal lesions because of increased contrast enhancement and tomographic effect with the latter, allowing for precise anatomic localization of an uncovered abnormality. However, tomographic sections of curved structures or regions obliquely oriented to the reconstruction plane may have inherent limitations as far as case of image interpretation, which can be overcome by oblique reorientation of the SPECT views. A method for oblique angle presentation of the lumbar spine, pelvis, and hips has been developed with results correlated with radiographic tomograms of a phantom to order to ensure correct anatomic orientation. These oblique SPECT images allow for easier differentiation between facet and pars interarticularis abnormalities, as well as improved imaging of hips and sacrum.

Contrast Media↗
PubMed1996

Bone SPECT imaging of the painful back.

Bone SPECT imaging offers advantages over planar techniques based on improved contrast enhancement plus tomographic effect, with the latter allowing for precise anatomic localization of an abnormality. This is important when evaluating patients with back pain because placement of a lesion in the vertebral body, component of the vertebral arch, or disc space region significantly affects diagnostic possibilities and, in some circumstances, can effectively exclude malignancy in favor of benign disease. Such an approach to SPECT interpretation requires high-quality images capable of precise anatomic placement of a lesion and a systematic method of analysis based on recognition of normal anatomic relationships plus knowledge of the common presentations of bony abnormalities shown on SPECT scanning.

Back Pain↗
PubMed1991

A dose-attenuation shield for use in glomerular filtration rate computations. A method for combined renal scintiangiography and functional quantification.

Renal perfusion and function can be determined by renography using Tc-99m DTPA. However, the high dose of tracer necessary for scintiangiography may result in inaccurate syringe-count determinations when measured by the gamma camera necessary for calculating the glomerular filtration rate by a camera technique. This report describes a syringe shield, constructed at minimal cost, which allows for suitable count attenuation and use of high doses of tracer for assessment of both renal perfusion and function.

Adult↗
PubMed1988

Normal anatomy of the lumbosacral spine and pelvis. A correlation of SPECT and radiographic techniques.

SPECT of the lumbosacral spine and pelvis is an advancement over planar imaging, which allows for improved lesion detection and more precise anatomic localization of an abnormality. Recognition of skeletal anatomy shown by SPECT is paramount for diagnostic accuracy as well as for meaningful consultations with referring physicians and diagnostic radiologists. This is a correlative study of normal anatomy of the lumbosacral spine and pelvis demonstrated by SPECT and radiography in order to assure that morphologic detail resulting from SPECT is recognized and matched with radiographic landmarks in the same area.

Humans↗
PubMed1988

SPECT imaging of the lumbosacral spine and pelvis.

This is a prospective comparison of SPECT versus planar imaging of the lumbosacral spine and pelvis, performed in order to assess which technique was more useful in clinical practice. One hundred adults were studied with both techniques, and abnormalities uncovered by either imaging method were graded 1-4 based on the lesion's relative uptake intensity. SPECT imaging significantly improved lesion detection, especially in conditions resulting in only low grade tracer uptake on planar studies. Precision in anatomic localization furthermore improved the quality and usefulness of diagnostic information resulting from SPECT imaging compared to planar examinations. SPECT is recommended for routine imaging of the lumbosacral spine and pelvis in symptomatic patients, especially when planar examinations are normal or equivocal.

Adolescent↗
PubMed1987

Diagnosis of malignant pericardial effusion during dynamic hepatic scintigraphy.

Three clinically unsuspected malignant pericardial effusions were discovered during routine dynamic hepatic scintigraphy. The only common clinical feature shared by the patients was dyspnea. Static scintigrams alone would not have detected these effusions, which points out again the importance of including dynamic scintigraphy in routine radionuclide evaluations of the liver.

Aged↗
PubMed1986

Bone marrow island vs focal infection. An indium-111 leukocyte imaging dilemma.

An island of bone marrow surrounded by the glue used in securing a hip prosthesis accumulated In-111 leukocytes in a patient being imaged for hip pain. This was shown to be normal marrow uptake of labeled cells and not an abscess by performing bone marrow imaging. The appearance of the leukocyte and bone marrow scans of the area were identical.

Abscess↗
PubMed1986

Splenic "disappearance" during gated exercise nuclear angiocardiography.

Decreasing splenic activity occurred during the maximum exercise phase of gated stress testing in 24 patients who underwent 26 such studies. This event was related to increasing exercise, and correlated with the relative increase in heart rate, pulse-pressure product, and cardiac output, but not ejection fraction. A multiple linear regression analysis showed that the combination of increases in pulse-pressure product and cardiac output had the best correlation with decreasing splenic activity at the conclusion of exercise. Redistribution of cardiac output toward muscle and away from splanchnic viscera is a consequence of exercise, and is graphically demonstrated by decreasing splenic visualization, which in some patients was so marked as to result in disappearance of the organ from the video monitor.

Adolescent↗
PubMed1985

Creatinine clearance estimation from serum creatinine values: an analysis of three mathematical models of glomerular function.

The logarithmic relationship of serum creatinine and creatinine clearance was analyzed in 100 adult patient studies using a geometric regression technique. Each sex was independently analyzed, and the subsequently derived regression formulae were age corrected resulting in mathematical models useful in estimating creatinine clearance from serum creatinine concentrations. These formulae were tested prospectively in another group of 100 patient studies in which creatinine clearance had been determined, and the results compared to values derived by use of two other published formulae. This newer method resulted in a closer distribution of data around a line of identity compared to other formulae and allowed for a good "bedside" estimation of creatinine clearance from serum creatinine concentration.

Adolescent↗
PubMed1984

Computation of glomerular filtration rate with Tc-99m DTPA: an in-house computer program.

The glomerular filtration rate (GFR) can be computed from the scintigraphic determination of Tc-99m DTPA (diethylenetriaminepentaacetic acid) uptake within the kidneys. The required computations are straightforward and can easily be included in the software of various computers, including a hospital's existing data-processing system. This report presents a complete operational program based on extensive experience with this method. The program is easy to use, allows for adjustments to be made for unusual clinical conditions, and produces a permanent record that can be issued as part of the final report.

Computers↗
PubMed1983

Transient reduction in renal function following arteriography: a radionuclide study.

The effects of iodinated contrast agents upon renal function were determined in 11 patients undergoing arteriography. Serial radionuclide renograms were performed to calculate the glomerular filtration rate, effective renal plasma flow and filtration fraction before and after arteriography. The effective renal plasma flow was the parameter most adversely affected. The magnitude of renal dysfunction depended upon the amount of contrast medium administered, as well as probably pre-existing renal disease and site of injection.

Adult↗
PubMed1983

Split renal function testing using Tc-99m DTPA. A rapid technique for determining differential glomerular filtration.

The fractional renal uptake of intravenously administered Tc-99m DTPA, within 2 to 3 minutes following radiotracer arrival in the kidneys, is proportional to the glomerular filtration rate (GFR). Thus it is possible to determine total, as well as individual kidney, GFR by a radionuclide technique which needs only six minutes of patient time and requires neither blood nor urine samples. The radionuclide computed GFR correlates extremely well with 24-hour creatinine clearance determinations, and is highly reproducible. This method has been used in nearly 500 split renal function determinations and has provided valuable, accurate information.

Adolescent↗
PubMed1982

Assessment of cerebral perfusion in childhood strokes.

Thirty-three children who had strokes were studied by dynamic and static scintigraphy, 29 by CT scanning, and 10 by cerebral angiography. The accuracy of dynamic scintigraphy in stroke detection during the first week of clinical symptoms was 94% while CT scanning was 60% accurate and static scintigraphy 11% accurate. During the second week the accuracy of CT scanning increased to 100%, but static scintigraphy improved to only 50%. Fifty percent of scintiangiograms performed during the first week showed either luxuriant perfusion or flip-flop patterns. In some patients these two flow patterns changed to that of cerebral hemispheric ischemia after going through a phase during which perfusion appeared to be equal in the two hemispheres. Dynamic scintigraphy is believed to be the test of choice for stroke detection in children during the first week.

Adolescent↗
PubMed1982

Glomerular filtration rate: estimation from fractional renal accumulation of 99mTc-DTPA (stannous).

99mTc diethylenetriaminepentaacetic acid (stannous) is cleared from the blood by glomerular filtration. However, calculation of the glomerular filtration rate has required analysis of serial blood samples drawn over intervals of several hours in order to determine the radionuclide clearance rate. This lengthy procedure can be circumvented by the direct scintigraphic determination of fractional radionuclide accumulation within each kidney, occurring at a specified time interval after radionuclide administration. This value has been correlated with 24 hr creatinine clearance values in a group of hospitalized patients. From these data, a formula was derived allowing for estimation of total glomerular filtration rate, as well as individually for each kidney, without requiring blood samples. This procedure needs only 6 min of patient time.

Adolescent↗
PubMed1980

Necrosis of Wilms tumors.

Gray scale ultrasonography, arteriography and excretory urography were done in 17 children with Wilms tumor. The results of these studies were correlated with the pathological specimen. At the time of operation 71 per cent of the tumors were necrotic. Ultrasonography predicted correctly the internal consistency of Wilms tumors in 94 per cent of the cases, while arteriography was 64 per cent and excretory urography was 41 per cent accurate. This information regarding neoplastic degeneration added to the completeness of the radiographic examination and forewarned the surgeon of a potentially difficult resection.

Adolescent↗
PubMed1980

Cholestatic syndromes in infancy and childhood.

Of 33 children with various cholestatic syndromes who were studies with sonography, 19 also had 131I rose bengal scintigraphy, and 12 also had 99mTc sulfur colloid scintigraphy. Patients were categorized into intra- or extrahepatic etiologies for their cholestasis. Of 19 children in the extrahepatic category, 17 had abnormal sonographic studies; two with biliary atresia appeared normal. All 14 patients in the intrahepatic category had normal sonographic studies. Rose bengal was most useful when demonstrating biliary patency. Some cases of biliary atresia with normal sonography and lack of rose bengal excretion into the intestinal tract could not be separated from cases of neonatal hepatitis using a similar combination of studies. Radiocolloid studies were less valuable than other examinations except when demonstrating diffuse hepatic reticuloendothelial dysfunction as found in two cases of congenital syphilitic hepatitis.

Bile Duct Diseases↗