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Biomedical subjects

A P Yudd

Publications and source records attributed to A P Yudd.

15 recordsLinked to original sources
PubMed1992

Hepatic SPECT imaging in the detection and clinical assessment of hepatocellular disease.

A total of 95 patients, including 45 people with no evidence of liver disease and 50 documented hepatocellular disease patients, were studied to assess the value of planar and SPECT scintigraphy in the evaluation of hepatocellular disease. The accuracy and concordance between techniques was assessed using two criteria. Criterion 1, heterogeneity of the tracer in liver, yielded a concordance of 64%, whereas with criterion 2, liver and spleen tracer pattern, concordance was 78%. SPECT was significantly more accurate than planar imaging (P < 0.01), using both criteria. The clinical severity of the hepatocellular disease was further assessed in 72 of the patients and correlated with a liver scan severity rating scale. The SPECT technique showed a good correlation (r = 0.89) with the composite clinical severity score; however, no significant relationship with planar imaging was noted. The results of this study suggest that liver SPECT is a reliable technique for the assessment of hepatocellular disease.

Aged↗
PubMed1991

Interventions and functional brain imaging.

Assessment of regional cerebral blood flow (rCBF) is useful in the evaluation of cerebral vascular disease. However, a single resting study has limitations in that a normal rCBF may be present with diminished cerebral vascular flow reserve and regions of decreased rCBF may be seen with diaschisis or selective neuronal loss and an intact vascular supply. To help differentiate these conditions a stress rCBF study can be obtained following the administration of vasodilatory stimulus. The topic of this review is the discussion of single photon emission computed tomography (SPECT) and vascular intervention, primarily, acetazolamide (Diamox, Lederle Laboratory Division, Pearl River, NY) augmented SPECT in the evaluation of cerebral vascular disease.

Acetazolamide↗
PubMed1989

The potential value of serial cerebral SPECT scanning in the evaluation of psychiatric illness.

Cerebral SPECT imaging has the potential to make an important contribution to clinical psychiatry. Cerebral SPECT scanning, stimulated by the work with PET, is readily available and much less expensive than PET. This paper reports a case demonstrating the potential value of cerebral SPECT scanning with I-123 IMP, specifically in the serial evaluation of a schizophrenic patient with auditory hallucinations. The initial scan revealed focal areas of increased uptake in the caudate nuclei of the basal ganglia, and in the right temporal lobe. After pharmacological treatment with clinical improvement, the follow-up SPECT scan demonstrated significant improvement in the distribution of the radiopharmaceutical.

Adult↗
PubMed1988

Single photon emission computed tomography and transmission computed tomography in the evaluation of liver disease.

To assess the relative strengths of hepatic SPECT and transmission computed tomography (TCT), a comparison of these methods was made in 88 patients during a 20-month period. The scans were classified into four categories: normal, solitary focal, multifocal, or diffuse hepatocellular patterns. The final disease category was determined by histologic evaluation-biopsy/autopsy, surgery, or a combination of ultrasound, laboratory, and clinical follow-up for a minimum of 6 months. Both SPECT and TCT were normal in the 47 patients classified as normal. Of the 16 patients with diffuse hepatocellular disease, SPECT correctly identified 16 and TCT identified two patients. Eleven patients had solitary focal disease; 11 were detected by SPECT and 10 by TCT. Fourteen patients were in the multifocal disease group; 13 were detected by SPECT and 10 by TCT. Overall, SPECT and TCT findings were in agreement in 68 (77%) of the cases. This study demonstrates that SPECT is equal to TCT in the assessment of the liver parenchyma in normal and focal disease states and that SPECT is superior in the assessment of diffuse disease.

Adult↗
PubMed1988

The value of SPECT imaging in the diagnosis of hepatic hemangioma.

Radionuclide flow studies, planar, and SPECT hepatic blood pool imaging were performed in 23 patients with 39 hepatic hemangiomas, 23 patients with primary and secondary liver tumors, 12 patients with hepatocellular disease, two patients with hepatic cysts, and 10 patients with no evidence of liver disease. The hepatic SPECT imaging identified all 39 hemangiomas as having a sequestration pattern compared with a yield of 69% (27 of 39 cases) for the planar imaging. None of the 47 other patients demonstrated this pattern. The SPECT approach is considered superior to planar blood pool imaging because of improved diagnostic yield, reduced patient imaging time, and greater ease of correlation with other cross-sectional imaging modalities.

Adult↗
PubMed1987

Abdominal SPECT imaging.

Over the past several years, abdominal single photon emission computed tomography (SPECT) imaging has evolved from a research tool to an important clinical imaging modality that is helpful in the diagnostic assessment of a wide variety of disorders involving the abdominal viscera. Although liver-spleen imaging is the most popular of the abdominal SPECT procedures, blood pool imaging is becoming much more widely utilized for the evaluation of cavernous hemangiomas of the liver as well as other vascular abnormalities in the abdomen. Adjunctive indium leukocyte and gallium SPECT studies are also proving to be of value in the assessment of a variety of infectious and neoplastic diseases. As more experience is acquired in this area, SPECT should become the primary imaging modality for both gallium and indium white blood cells in many institutions. Renal SPECT, on the other hand, has only recently been used as a clinical imaging modality for the assessment of such parameters as renal depth and volume. The exact role of renal SPECT as a clinical tool is, therefore, yet to be determined.

Gallium↗
PubMed1987

Quantitative autoradiography of parathyroid glands in rats with carbon-14-labeled amino acids.

We have utilized a quantitative autoradiographic method as a means of evaluating amino acid uptake of the rat parathyroid gland for the ultimate purpose of finding agents potentially suitable for position emission tomographic scanning of parathyroid glands. L-[1-14C]leucine and L-[guanido-14C]arginine were evaluated because of their relatively high content in the synthetic products of the parathyroid glands compared with other neck tissues, thyroid gland, and muscle. Carbon-14 leucine disappeared rapidly from plasma following intravenous injection and there was relatively selective uptake of the [14C]leucine and [14C]arginine by the parathyroid glands when compared with uptake by the thyroid gland and neck muscle. These data suggest that both agents warrant further investigation for their potential utility in positron emission tomographic scanning of the parathyroid gland.

Amino Acids↗
PubMed1977

Identification of retinal isomers isolated from bacteriorhodopsin.

The purple membrane of Halobacterium halobium contains the protein bacteriorhodopsin which resembles the visual pigment, rhodopsin, in many aspects. The isomeric configurations of its chromophore, retinal, were studied by a combination of methylene chloride extraction and analysis by high-pressure liquid chromatography. The light-adapted form bR570LA yields solely all-trans-retinal, while the dark-adapted form of bacteriorhodopsin, bR560DA, yields a mixture of 13-cis and all-trans with a ratio of similar to 1;1. The photointermediate M412 in a membrane modified by ether at high NaCl concentration also yields an approximately 1:1 mixture of 13-cis-and all-trans-retinals, while a similar M405 species produced by illumination in 2 M guanidine hydrochloride at high pH yields mainly 13-cis-retinal. These results indicate that the photochemical cycle of bR570LA may involve an isomerization of the retinal chromophore from the all-trans to the 13-cis form.

Bacteriorhodopsins↗