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Biomedical subjects

T C Hill

Publications and source records attributed to T C Hill.

At least 37 records · Page 2Linked to original sources
PubMed1985

Muscarinic acetylcholine receptors in Alzheimer's disease. In vivo imaging with iodine 123-labeled 3-quinuclidinyl-4-iodobenzilate and emission tomography.

In vivo imaging of muscarinic acetylcholine receptor binding function in a patient with Alzheimer's disease, using single-photon emission computed tomography and iodine 123-labeled 3-quinuclidinyl-4-iodobenzilate (123I-QNB), and perfusion imaging using 123I-N-isopropyl p-iodoamphetamine are described. A profound decrease in perfusion to the posterior temporal and parietal cortex and a more uniform uptake of 123I-QNB throughout the cerebral cortex were observed. The 123I-QNB activity ratio was reduced compared with that of a normal age-matched subject, suggesting a moderate impairment in muscarinic receptor binding function in Alzheimer's disease. Furthermore, and more importantly, our study demonstrates that images of in vivo receptor binding can be obtained easily and nontraumatically using 123I-QNB and single-photon emission computed tomography.

Alzheimer Disease↗
PubMed1985

Clinical brain imaging with isopropyl-iodoamphetamine and SPECT.

In recent years, fierce competition has developed between the new high technology specialties of ultrasound, nuclear medicine, computerized transmission tomography, and most recently, nuclear magnetic resonance. Conventional brain scintigraphy, once the most common nuclear medicine procedure, has fallen victim to this rivalry despite the fact that routine scintigraphy remains a good diagnostic test. The agony of this defeat initially caused self-doubt among nuclear medicine physicians, but out of this gloom has emerged a number of radionuclide tests which have the potential to revolutionize how clinical neurology/psychiatry is practiced.

Amphetamines↗
PubMed1985

Delayed images of glucoheptonate distribution after renal transplant.

Thirteen consecutive patients who had undergone renal transplantation were scanned 24 hours after glucoheptonate injection to document the incidence of gastrointestinal activity mimicking urinary extravasation. In six of the 13 patients, the activity was clearly within the small bowel or the colon but, in seven patients, the activity was noted surrounding the renal allograft. Using scintigraphy alone, it could not be determined whether this appearance represented cecal activity or urinary extravasation.

Adult↗
PubMed1985

Subintimal dissection of peritoneovenous shunt tubing. Demonstration with radionuclide study.

A case report is presented in which malfunction of a peritoneovenous shunt was caused by subintimal dissection of the venous end of the shunt tubing. The radionuclide shunt patency study demonstrated a collection of radioactivity at the venous end of the tubing, representing the abnormal intramural collection of peritoneal fluid. Scintigraphic demonstration of this complication of a peritoneovenous shunt has not been reported previously.

Ascites↗
PubMed1985

Sphincter of Oddi stenosis: diagnosis using hepatobiliary scintigraphy and endoscopic manometry.

To determine the role of radionuclide imaging in diagnosing sphincter of Oddi stenosis, 21 patients with symptoms suggesting this disorder underwent endoscopic retrograde cholangiopancreatography, cholescintigraphy, and, when possible, endoscopic manometry. Those patients with abnormal hepatobiliary scintigraphy results--based on our criteria of delayed biliary intestinal transit, abnormal duct size, and abnormal time-activity dynamics and obstruction--had a mean basal sphincter pressure of 38.5 mm Hg. Sphincter pressures could not be measured in six patients with sphincters too tight to cannulate. Ten patients who underwent hepatobiliary scanning both before and after sphincter surgery had normal scan results on the repeat study. Hepatobiliary imaging appears useful for diagnosis of sphincter of Oddi stenosis in selected patients in whom manometry cannot be performed and for objective assessment of response to therapy.

Adult↗
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

Thyroid nodules: sonographic-pathologic correlation.

Sonographic patterns of thyroid disease were correlated with pathologic findings. Twenty-eight cadaver thyroid glands were prospectively examined with a high-resolution real-time ultrasound scanner. Ultrasound findings were correlated in detail with gross and microscopic findings. Ultrasound is very accurate in detecting architectural variation, adenomatous goiter, and solitary nodules. Ultrasound cannot distinguish benign from malignant nodules, but it can be used to measure changes in nodule size. Glandular asymmetry and multiple solid nodules must be present for confident diagnosis of adenomatous goiter; hemorrhage, necrosis, and calcific spherules may be present in varying amounts. Fibrous septae, dilated follicles, and vascular calcification are found in normal aging thyroid glands. Using these criteria, ultrasonography is very accurate in the diagnosis of adenomatous goiter.

Adenocarcinoma↗
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↗
PubMed1984

A comparison of two cerebral perfusion tracers, N-isopropyl I-123 p-iodoamphetamine and I-123 HIPDM, in the human.

Both N-isopropyl I-123 p-iodoamphetamine (IMP) and I-123 HIPDM have been advocated as radiotracers for assessing regional cerebral perfusion. We compared the biodistribution of the two tracers in 19 patients without evidence of neurological disease. Following intravenous injection, both tracers accumulated initially in the lung. Early after injection the fraction of the total brain uptake was higher for I-123 HIPDM than for I-123 IMP. The peak brain activity for I-123 IMP was higher than for I-123 HIPDM . Brain activity was unchanged with both tracers between 30 and 60 min after injection. Tomographic images were similar in appearance for both tracers. No eye uptake greater than background was observed with either tracer in any patient at 2, 24, and 48 hr. I-123 IMP is superior for tomographic imaging because of its higher brain uptake, whereas I-123 HIPDM may be superior for studies performed during rapid changes in blood flow.

Amphetamines↗
PubMed1984

The relationship of the eye uptake of N-isopropyl-p-[123I]iodoamphetamine to melanin production.

Eye uptake has been a potential concern with N-isopropyl-p-[123I]iodoamphetamine (I-123 IMP) because it has been observed in certain animal species. We have investigated the cause of the eye uptake and its relationship to melanin synthesis. In a 1-yr-old cynomolgus monkey, high concentration of the tracer was seen in the eyes regardless of the type of anesthesia (pentobarbital or ketamine) or the oral administration of Lugol's solution. The eye uptake at 24 hr after injection of I-123 IMP was equally high in an 8-yr-old rhesus monkey. The ratio of radioactivity in the eye of black compared with white albino mice was 10:1 at 30 min, 18:1 at 2 hr and 36:1 at 24 hr after injection of I- 123 IMP. No eye uptake above soft-tissue background was seen in five patients at 2, 24, and 48 hr after injection. I-123 IMP is avidly incorporated into melanocytes actively producing melanin, but substantially less in melanocytes where production of melanin has ceased as in the human eye.

Amphetamines↗
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

Biodistribution and dosimetry of N-isopropyl-p-[123I]iodoamphetamine in the primate.

The biodistribution of N-isopropyl-p-[123I]iodoamphetamine (I-123 IMP) in the Macaca fascicularis monkey was determined at 15 min and at 1, 4, 24, and 48 hr after intravenous injection. Brain uptake was 7.8% of the injected dose at 1 hr, with little change in concentration between 15 min and 1 hr, falling thereafter. Eye uptake reached a maximum of 0.23% of injected dose at 24 hr, with activity primarily in the pigmented layers. The human absorbed radiation dose was calculated on the basis of biodistribution data. The critical organ is the eye (0.407 rad/mCi of I-123 IMP). The eye dose increased to 1.11 rad/mCi with 4% contamination from I-124 IMP and to 0.535 rad/mCi with 0.4% contamination from I-125 IMP. The absorbed dose to the liver was 0.127 rad/mCi for pure I-123 IMP and the thyroid dose was 0.120 rad/mCi, both increasing with either I-124 or I-125 contamination. While delayed eye uptake has not yet been reported in the human, care should be exercised in limiting the amount of contaminating I-124 or I-125 to the lowest practical level.

Absorption↗
PubMed1982

Comparison of N-isopropyl (I-123) p-iodoamphetamine brain scans using Anger camera scintigraphy and single-photon emission tomography.

N-isopropyl (I-123) p-iodoamphetamine (IMP), which is extracted by the brain in proportion to regional blood flow, has been shown to be useful with single-photon emission tomography (SPECT) in the assessment of pathologic states related to blood flow. Because emission tomographic equipment is not yet available at most hospitals, the authors compared IMP brain images obtained with an Anger camera with those obtained by SPECT to determine the usefulness of IMP scintigraphy. Thirty-nine pairs of studies were performed on 12 control patients, 14 patients with stroke, three patients with tumors, and a miscellaneous group of eight patients. Planar scintigraphy showed good correlation with SPECT in determining the presence or absence of abnormality in all patients except one with a very small brain stem infarction that was not detected by planar imaging. Anger images showed poor contrast resolution compared with SPECT images. It is thus expected that SPECT will result in better lesion detection when smaller lesions are studied. Planar scintigraphy is not capable of providing quantitative measurement of regional cerebral blood flow.

Amphetamines↗