Extraction of [99mTc]-d,l-HM-PAO across the blood-brain barrier.

The initial extraction (E) across the blood-brain barrier (BBB) of [99mTc]-d,l-HM-PAO after intracarotid injection was measured in 14 Wistar rats and 6 patients using the double indicator, single injection method with Na-24 as the cotracer. In both series, cerebral blood flow (CBF) was measured using the initial slope of the xenon-133 washout curve after intracarotid bolus injection. In rats, bolus size (20 or 120 microliters), bolus type (saline or 10% albumin), or CBF were changed.

The retention mechanism of technetium-99m-HM-PAO: intracellular reaction with glutathione.

Preparations of d,l- and meso-hexamethylpropyleneamine oxime (HM-PAO) labeled with technetium-99m were added to rat brain homogenates diluted with phosphate buffer (1:10). The conversion of d,l-HM-PAO to hydrophilic forms took place with an initial rate constant of 0.12 min-1.

Assessment of the arterial input curve for [99mTc]-d,l-HM-PAO by rapid octanol extraction.

The in vitro conversion of the lipophilic molecule [99mTc]-d,l-hexamethylpropyleneamine oxime [( 99mTc]-d,l-HM-PAO) to a hydrophilic form was studied in saline, plasma, and blood at 37 degrees C by paper chromatography and by octanol extraction. The octanol:saline ratio was 79.9.

Osteomyelitis.

The use of 111In-labelled granulocyte scintigraphy is recognized as a reliable method for detecting osteomyelitis and has similar sensitivity and significantly increased specificity compared to bone scintigraphy and 67Ga studies. Recent published work using pure granulocytes labelled with 111In tropolonate to detect osteomyelitis resulted in sensitivity of 100% and specificity of 92%. 99Tcm as an alternative granulocyte label offers advantages of convenience, lower radiation dose and higher image resolution.

Inflammation: imaging with Tc-99m HMPAO-labeled leukocytes.

Leukocytes labeled with technetium-99m hexamethylpropyleneamine oxime (HMPAO) were used in 100 patients: 32 with suspected inflammatory bowel disease, 17 with fever of unknown origin, 21 with suspected abdominal sepsis, 20 with suspected bone sepsis, seven with bronchiectasis, and three with recent myocardial infarction. The distribution of activity in patients subsequently shown not to have inflammatory bowel disease was similar to that previously described for indium-111-labeled leukocytes. However, in this study, activity was also seen in the kidneys and bladder and occasionally the gallbladder on both early (1-3 hours) and late (24 hours) views, and in the colon in late views.

Initial experience with technetium-99m HM-PAO brain SPECT.

Technetium-99m hexamethylpropyleneamineoxime ([99mTc]HM-PAO) brain single photon emission computed tomography (SPECT) was performed with a dual head rotating scintillation camera. Normal tracer distribution and side/side differences of counting rates were obtained in 11 healthy volunteers. Almost stable gray/white matter ratios were found (1.

Serial studies of cerebral blood flow using 99Tcm-HMPAO: a comparison with 133Xe.

We have compared the regional distribution of 99Tcm-HMPAO with regional cerebral blood flow (rCBF). CBF was measured by single photon emission computerized tomography (SPECT) using a TOMOMATIC 64 after 133Xe inhalation in 41 patients. With the same SPECT device the distribution of 99Tcm-HMPAO was measured after i.

Technetium-99m d,l-HM-PAO: a new radiopharmaceutical for SPECT imaging of regional cerebral blood perfusion.

Following investigation of a large number of new ligands based upon propylene amine oxime (PnAO) the d,l-diastereoisomer of hexamethyl propyleneamine oxime (HM-PAO) was selected as the preferred ligand for 99mTc as a tracer for cerebral perfusion imaging. The neutral, lipophilic 99mTc complex of d,l-HM-PAO was formed in high yield by stannous reduction of 99Mo/99mTc generator eluate using a kit formulation of the ligand. Two minutes following i.

Evaluation of regional cerebral blood flow with 99mTc-d, 1 HM-PAO and SPECT.

The imaging of regional cerebral blood flow (rCBF) by 99mTc-d, 1 HM-PAO and SPECT is described. Its relevance to clinical syndromes, such as stroke, transient ischemic attacks, various forms of dementia, epilepsy, and subarachnoid hemorrhage, is reported.

Technetium-99m-d, 1-HM-PAO: a new radiopharmaceutical for imaging regional brain perfusion using SPECT--a comparison with iodine-123 HIPDM.

A new radiopharmaceutical, technetium-99m hexamethylpropyleneamine oxime (99mTc-d, 1-HM-PAO), has been reported to cross the blood-brain-barrier and to distribute in brain in proportion to regional blood flow. This study reports brain imaging obtained with 99mTc-d,1 HM-PAO in 20 subjects; seven without evidence of cerebral disease and 13 with cerebrovascular disorders. In 16 patients comparative data were available with N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-iodobenzyl)-1,3-propanediamine ([123I]HIPDM).

Clinical experience with 99mTc-hexamethylpropylene-amineoxime for labelling leucocytes and imaging inflammation.

Hexamethylpropylene-amineoxime (HMPAO) forms a lipid-soluble neutral complex with 99mTc which is rapidly incorporated into leucocytes in vitro. In six patients with suspected or known inflammatory disease, a "mixed" leucocyte suspension isolated from 85 ml blood anticoagulated with acid-citrate-dextrose was labelled by 99mTc-HMPAO with a mean efficiency of 47% (SE2%), of which 78% (3) was taken up by granulocytes. Activity eluted more rapidly from other cell types in vitro than from granulocytes, which remained firmly labelled.

A comparative study of the brain uptake and early kinetics of 99mTc-dl HM-PAO and other PnAO derivatives in baboons.

Derivatives of propylene-amine-oxime (PnAO) have been synthesized which form a neutral lipid-soluble complex with 96mTc and can be supplied as freeze-dried kits. The complexes cross the intact blood-brain barrier. This report shows the brain uptake, early kinetics and biodistribution in normal adult baboons of 5 99mTc-PnAO derivatives and 2 isomers of one of the tested derivatives (HM-PAO).

Technetium-99m HM-PAO stereoisomers as potential agents for imaging regional cerebral blood flow: human volunteer studies.

A total of nine normal volunteer subjects were studied with three forms of [99mTc] hexamethylpropyleneamineoxime (HM-PAO), a potential cerebral blood flow imaging agent. One, the d,l isomer, showed 4.1% uptake in the brain which remained constant over 8 hr.

Evaluation of a 99Tcm bound brain scanning agent for single photon emission computed tomography.

D,L HM-PAO-99Tcm (PAO) is a lipophilic tracer complex which is avidly taken up by the brain. We have compared the regional distribution of PAO with regional cerebral blood flow (CBF). CBF was measured by single photon emission computed tomography (SPECT) by Tomomatic 64 after 133Xe inhalation in 41 patients.

A 99Tcm-labelled radiotracer for the investigation of cerebral vascular disease.

The first clinical data is given on 99Tcm-hexamethylpropyleneamine oxime (HM-PAO) in normal subjects and patients with established stroke. Regional cerebral blood flow maps (rCBF) have been recorded and displayed in tomographic mode with this new radiopharmaceutical. Good images were obtained, comparable to those achieved with 123I-isopropylamphetamine (IMP).

In vivo 19F NMR imaging of liver, tumor, and abscess in rats. Preliminary results.

In vivo magnetic resonance imaging (MRI) has employed almost exclusively the proton because of its high gyromagnetic ratio and natural abundance relative to other nuclei. Recent research has focused on imaging using nuclei other than 1H, but has been limited by the decreased sensitivity and/or low biologic concentrations of the nuclei. Fluorine (19F), with a gyromagnetic ratio second only to that of hydrogen, is a theoretically attractive nucleus for MRI, but fluorine is present in only minute amounts in most tissues.

Astatine-211--tellurium radiocolloid cures experimental malignant ascites.

An investigation of the efficacy of astatine-211--tellurium colloid for the treatment of experimental malignant ascites in mice reveals that this alpha-emitting radiocolloid can be curative without causing undue toxicity to normal tissue. By comparison, negatron-emitting phosphorus-32 as colloidal chromic phosphate had no antineoplastic activity. The most compelling explanation for this striking difference is the dense ionization and short range of action associated with alpha-emission.

Potential column chromatography for ionic Ga-68. II: Organic ion exchangers as chromatographic supports.

A potential Ge-68 leads to Ga-68 generator system, based on the adsorption of Ge-68 from a dilute hydrofluoric acid eluent onto a commercially available organic anionexchange resin, is described. The distribution coefficients between the resin and dilute hydrofluoric acid were measured for germanium and gallium, and the breakthrough of germanium from a generator column determined. Using 0.

Tantalum-178-labeled agents for lung and liver imaging.

Despite its 9.3-min half-life, Ta-178 can be used to produce radiopharmaceuticals for lung and liver imaging. A variety of human serum albumin microspheres and other particulate radiopharmaceuticals were labeled with Ta-178.

Potential column chromatography generators for ionic Ga-68. I. Inorganic substrates.

Chemical separations for Ga-68 from Ge-68 using adsorption chromatography on inorganic materials are described. The adsorbents used were TiO2, ZrO2, and SiO2. Distribution coefficients for Ge and Ga on these absorbents were determined as a function of reagent concentration and duration of equilibration.

Scintigraphic imaging with tantalum-178 and the Anger scintillation camera: concise communication.

Tantalum-178 is a short-liver radionuclide (T 1/2 = 9.3 min.) and emits primarily 56- to 64-keV characteristic x-rays.

Cardiac imaging with tantalum-178.

Tantalum-178 is a potential tracer for the first transit studies of the heart. It has a short physical half-life (9.3 minutes) and is obtained as a generator product from its long-lived (21.