Synthesis of isomers of 18F-labelled amino acid radiopharmaceutical: position 2- and 3-L-18F-alpha-methyltyrosine using a separation and purification system

To diagnose cancers with radiolabelled amino acid using positron emission tomography, we have constructed a separation and purification system for the production of L-18F-alpha-methyltyrosine (L-18FAmT). This system could provide radioprotection and consistent production of L-18FAmT. L-18FAmT was synthesized and purified and the efficiency of the system was examined. The radiochemical yield of L-18FAmT was 20.3 +/- 5.1% (n = 5) based on the radioactivity trapped in the reaction vessel. The radiochemical purity was greater than 99.4 +/- 0.3% (n = 5). The radiochemical stability in phosphate-buffered saline and human plasma was examined and little decomposition was observed by HPLC analysis. Our results indicate that the separation and purification system gave simple and quick synthesis of L-18FAmT with a large reduction in radiation exposure and consistent production of L-18FAmT.

Contrast enhancement of PC-3 prostate cancer for magnetic resonance imaging: animal studies using tumor-localizing Mn-metalloporphyrin (THF-Mn-Asp)

PURPOSE

The objective of the present study was to test, in nude mouse PC-3 tumors, the contrast enhancement of 2,4-bis(1-tetrahydro-fulfuroxyethyl)-deuteroporphynyl(IX)-6- 7-bisaspartic acid (THF-Mn-ASP), which is a hematoporphyrin derivative and depresses T1 relaxation time on magnetic resonance (MR) imaging.

MATERIALS AND METHODS

THF-Mn-ASP or gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was intravenously administered, and MR imaging of the tumors transplanted into nude mice was performed on T1-weighted images.

RESULTS

After administration of THF-Mn-Asp, the signal intensity of PC-3 tumors increased and the tumor/muscle intensity ratio was highest at about 1 hour. The tumor/muscle intensity ratio, in contrast, was highest at about 5 minutes after administration of Gd-DTPA. The increase in intensity ratio was 32% in THF-Mn-ASP and 28% in Gd-DTPA.

CONCLUSION

The preliminary study suggested that THF-Mn-Asp has a predilection to accumulate in PC-3 tumors, and it seems to provide good contrast enhancement with tumor specificity for MR imaging.

Myocardial infarction in rats: high-resolution single-photon emission tomographic imaging with a pinhole collimator

The purpose of this study was to evaluate the accuracy of myocardial imaging by means of high-resolution single-photon emission tomography (SPET) with a pinhole collimator in rats with experimental infarction. Myocardial infarctions were induced in male Wistar rats by ligation of the left coronary artery for 30 min, followed by reperfusion. Two days after the reperfusion, pinhole SPET was performed after the intravenous administration of 111 MBq of thallium-201 chloride, using a rotating gamma camera equipped with a pinhole insert (2.0-mm aperture) in a low-energy pinhole collimator. SPET projection data were collected at 6 degrees increments over 360 degrees using a 4-cm radius of rotation to reconstruct the short- and long-axis images. Projection data were acquired in 15 or 30 s, the SPET imaging being accomplished within 40 min after the injection of 201Tl. After SPET, the rats were sacrificed to remove the hearts for autoradiography (ARG) and nitroblue tetrazolium (NBT) staining as a visual correlative study. Quantitative correlative studies between pinhole SPET and ARG were performed with linear regression analysis for infarct size and distribution properties (relative counts on SPET images and relative density on autoradiographs) on the short-axis sections. All infarcts (4 mm in minimum diameter) in seven rats were detected by pinhole SPET. The SPET images in rats with or without myocardial infarction were consistent with the findings of ARG and NBT staining. There were significant correlations between pinhole SPET and ARG with respect to the infarct size (r=0.933, P <0.001; n=15) and the relative radiotracer distribution (r=0.931, P <0.001; n=68). This study therefore confirmed the accuracy of myocardial pinhole SPET imaging in rats with myocardial infarction. This method may partially substitute for ARG and prove useful for assessing new myocardial imaging agents in vivo in small laboratory animals.

[Tumor diagnosis using 18F-FDG SPECT]

Fluorine-18-fluorodeoxyglucose (18F-FDG) single photon emission CT(SPECT) imaging was performed in four patients with malignant neoplasms. Acquisition of SPECT was started 40 minutes after intravenous administration of 370MBq of 18F-FDG using dual-headed gamma camera equipped with 511keV collimators. Whole body planar scintigraphy was also obtained after the SPECT study. Tumor uptake of 18F-FDG was detected in three of four patients on both SPECT and planar images, and a 2.5 x 1.5 cm lung tumor was clearly visualized on SPECT image. Excellent SPECT image of 18F-FDG using a conventional gamma camera system is promising for the wide use of this system in cancer diagnosis.

Indirect labeling of macroaggregated albumin with indium-111 via diethylenetriaminepentaacetic acid

It is ideal to perform a simultaneous pulmonary perfusion and ventilation scan in cases of suspected pulmonary thromboembolism. Indium-111 (111In)-diethylenetriaminepentaacetic acid (DTPA)-macroaggregated albumin (MAA) was designed for this purpose. MAA was conjugated with DTPA at a molar ratio of 1:100 and incubated with 111In-chloride for 30 min at room temperature. DTPA-MAA could be labelled with 111In above a 96% labelling efficiency without MAA particle aggregates making their particles larger than desirable. The obtained 111In-DTPA-MAA was intravenously injected into normal mice and their biodistribution was studied at 15 and 180 min after injection. A gamma camera image was obtained 15 min after injection. 111In-DTPA-MAA was stable in vitro and in vivo, and gave high uptake of murine lung in the biodistribution study and clearly visualized murine lung in the scintigraph. Using 111In-DTPA-MAA as a pulmonary perfusion agent, a simultaneous pulmonary perfusion and ventilation scan with technetium-99m-ventilation agents is able to be performed using the dual-isotope technique. 111In-DTPA-MAA may be a potential pulmonary perfusion agent.

[A basic and clinical evaluation of a new immunoradiometric assay kit for human serum tissue polypeptide antigen (TPA)]

A new immunoradiometric assay kit (IRMA) of human serum tissue polypeptide antigen (TPA) based on combination monoclonal antibodies was evaluated. Using a new TPA-IRMA, the procedure of TPA measurement was faster and the range of measurement was more wide than a conventional TPA-IRMA. 89% (76/85 cases) of patients with malignant tumor and 96.4% (27/28) of patients with metastatic malignant tumor were positively detected. This assay of new TPA-M kit is sensitive to the level of serum TPA which is corresponding to a therapy. It is concluded that a new TPA-IRMA is very useful in monitoring and assessing malignant tumors.

Independent thallium-201 accumulation and fluorine-18-fluorodeoxyglucose metabolism in glioma

SPECT with 201TI is an effective procedure for evaluating the malignancy of glioma. Our goal was to investigate the diagnostic relevance of both 201TI SPECT and [18F]fluorodeoxyglucose (FDG) PET and the relation between 201TI uptake and glucose metabolism in glioma using comparative SPECT and PET studies.

METHODS

Thallium-201 SPECT and FDG dynamic PET studies were performed in 20 patients with untreated glioma (5 with glioblastoma, 5 with anaplastic glioma, 10 with low-grade glioma). Thallium-201 uptake in the tumor was estimated using the 201TI index, defined as the ratio of 201TI uptake in the tumor to that in the contralateral normal brain on SPECT images obtained 15 min after intravenous injection. We measured regional glucose metabolic parameters, including rate constants and regional cerebral metabolic rate of glucose utilization (rCMRgl), in the tumor. We then compared the regional 201TI index and glucose metabolic parameters with the histologic characteristics, malignancy and computed tomographic/ magnetic resonance imaging findings. In addition, we investigated the correlation between the 201TI index and glucose metabolic parameters.

RESULTS

Thallium-201 SPECT showed abnormal 201TI uptake in all patients with glioblastoma and anaplastic glioma. Thallium-201 indices of glioblastoma (202.6 +/- 22.1%) and anaplastic glioma (176.6% +/- 26.6%) were significantly higher than that for low-grade glioma (106.7% +/- 13.8%). The rCMRgl value of glioblastoma (17.6 +/- 3.5 mumole/100 g/min) was also significantly higher than that for low-grade glioma (10.8 +/- 4.5 mumole/100 g/min), although rCMRgl showed a large variability in both high- and low-grade glioma. Rate constants of FDG kinetics had no correlation with histological grade of glioma. Some patients with high-grade glioma, however, showed false-negative results with FDG-PET because of high normal brain uptake of FDG. Conversely, most low-grade glioma could not be localized by 201TI SPECT. There was no correlation between the 201TI index and glucose metabolic parameters.

CONCLUSION

Thallium-201 indices and rCMRgl values for glioblastoma were higher than those for low-grade glioma. Thallium-201 uptake in the tumor may be independent of increased glucose transport or metabolism. Thallium-201 SPECT and FDG-PET are complementary in the diagnosis of glioma, although 201TI SPECT is more significantly correlated with the malignancy of glioma.

A "changing stripe sign" in serial pulmonary perfusion imaging

A stripe sign in pulmonary perfusion imaging is reported to be predictive of the absence of pulmonary embolism in the specific area of the stripe sign, and generally does not change on serial pulmonary perfusion imaging. The authors present the case of a patient with a stripe sign that disappeared on serial perfusion imaging without a ventilation abnormality. A "changing stripe sign" may raise suspicion for the possible existence of acute pulmonary embolism.

Positron emission tomography with 4-[18F]fluoro-L-m-tyrosine in MPTP-induced hemiparkinsonian monkeys

PET imaging studies with 4-[18F]fluoro-L-m-tyrosine (FMT) in normal macaca monkeys showed selective accumulations of radioactivity in the striatum with time. In monkeys rendered hemiparkinsonian by intracarotid infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), FMT uptake was eliminated in the lesioned striatum. FMT-PET studies were able to detect dopaminergic terminals in both normal and hemiparkinsonian monkeys, and clearly showed a reduction in aromatic L-amino acid decarboxylase (AAAD) activities in the MPTP-lesioned striatum. These results show that FMT is promising as a PET tracer for the evaluation of central dopaminergic systems in parkinsonism.

[Measurement of serum TSH receptor antibodies in thyroid patients using TRAb Dade kits]

TRAb Dade kit is a radioreceptor assay that detects autoantibodies in serum of patients with thyroid diseases which interfere with the binding of 125I labeled TSH to its receptor. In this paper we examined the basic and clinical usefulness of newly developed TRAb assay kits. The intra and inter assay coefficients of variation were 7.9% and 8.4%, respectively. There was no significant effect of temperature and incubation time on TRAb values. The influence of conjugated, unconjugated bilirubin, hemoglobin and turbidity was not so significant on TRAb values. TRAb values in serum of 68 untreated Graves' disease were above the normal range, but most (78%) treated Graves' patients who became euthyroid after receiving antithyroid drug, showed the normal range. In patients with chronic renal failure TRAb values were also within the normal range. A significant correlation (y = 1.0x-0.88, r = 0.95) was observed between this TRAb kit and TRAb Cosmic values in various thyroid conditions. This new assay for TRAb was simple, rapid and reproducible. The measurement of serum TRAb values was useful for the evaluation of physiological and pathological function and seemed to be helpful in the management of patients with thyroid disease.

Bilateral subclavian vein thromboses presenting as a superior vena cava syndrome demonstrated by radionuclide blood flow and In-111 WBC imaging

A superior vena cava syndrome was caused by venous thrombosis of both proximal subclavian veins. Collateral pathways were clearly demonstrated by radioisotope venography. Indium-111 labeled platelet thrombography was useful in localizing thrombotic lesions.

[Clinical evaluation of safety, pharmacokinetics and dosimetry of the somatostatin analog 111In-DTPA-D-Phe-octreotide--report of the phase 1 study]

The safety, pharmacokinetics and dosimetry of the somatostatin analog 111In-DTPA-D-Phe-octreotide (111In-octreotide) were investigated in four young normal volunteers as phase 1 study in Japan. Neither adverse reactions nor significant changes of vital signs and clinical laboratory data were observed after intravenous injection of 111 MBq of 111In octreotide. The plasma clearance curve consisted of fast and slow exponential components with mean half life of 9.2 minutes and 2.2 hours, respectively. Seventy three percent of the injected dose were excreted in the urine by 24 hours after the injection of 111In-octreotide. With respect to the radiation dose to normal tissue, the most important organs were the urinary bladder, the kidney, the spleen and the liver. The effective dose equivalent was calculated as 3.26 +/- 0.43 mSv/37 MBq (mean +/- s.d.). This phase 1 study demonstrated the safety of scintigraphy with 111In-octreotide.

CYFRA 21-1 as a tumor marker used in measuring the serum fragment of cytokeratin subunit 19 by immunoradiometric assay

Serum levels of cytokeratin subunit 19 (CYFRA 21-1) were measured in 42 healthy volunteers, 104 cases of malignant diseases, 30 patients with chronic renal failure and 13 patients with nonmalignant and infectious diseases. The reliability of the method was demonstrated after dilution of serum samples and intra- and inter-assay reproducibility. Serum CYFRA-21-1 concentrations were less than 2.00 ng/ml in all healthy controls and 86% of the malignant cases had high serum CYFRA 21-1 levels. However slightly elevated values of CYFRA 21-1 were observed in most chronic renal failure patients. High correlation was observed between serum CYFRA 21-1 and Tissue Polypeptide Antigen (TPA) values (r = 0.90, n = 10) but not with serum alpha-feto protein (AFP) concentrations. Furthermore, cross binding tests with the CYFRA 21-1 tracer/CYFRA 21-1 antibody-coated beads and CYFRA 21-1 tracer/TPA antibody-coated beads also gave an almost linear graph. These results indicate that CYFRA 21-1 and TPA share similar type of antigens.

Reversible functional asplenia. Autoimmune hemolytic anemia with thrombocytopenia in chronic lymphocytic leukemia

An enlarged spleen failed to accumulate Tc-99m-labeled phytate, but it showed normal perfusion and uptake of labeled and heat-denatured red blood cells. A blood cell count demonstrated moderately low hemoglobin and hematocrit levels and a markedly low platelet count, and results of direct Coombs' and antiplatelet-antibody (IgG) tests were positive. Steroid therapy resulted in normal splenic function. This case demonstrates reversible functional asplenia caused by reticuloendothelial dysfunction secondary to pure splenic chronic lymphocytic leukemia.

Tissue lipid quantification using narrow bandwidth magnetic resonance imaging with a presaturation pulse

RATIONALE AND OBJECTIVES

Chemical-shift artifact occurs within tissues when band-like presaturation pulses are applied perpendicular to the frequency-encoding axis in narrow band-width magnetic resonance imaging. This phenomenon was used to quantify the lipid fraction in phantoms used to simulate tissue.

METHODS

Twenty phantoms with various lipid/water ratios were imaged on spin-echo sequence (repetition time/echo time, 2,000/20 msec) using a 1.5-T magnet. A narrow bandwidth that caused 6-mm chemical shift and a presaturation pulse 6-mm in width were used in the imagining. The lipid fraction values calculated from the resulting images were compared with values determined by a spectrometer.

RESULTS

The image-derived values (LI) correlated strongly with the values determined by spectrometry (LS) (LI = 0.97 + 0.99 LS, r = .998).

CONCLUSIONS

Chemical-shift artifact around the presaturation-applied areas should provide a simple and efficient method for the accurate quantification of tissue lipid fractions.

Preparation and clinical evaluation of technetium-99m dimercaptosuccinic acid for tumour scintigraphy

We describe a simple method of pentavalent technetium-99m dimercaptosuccinic acid [99mTc(V)-DMSA] preparation for the imaging of medullary carcinoma of the thyroid using commercially available kits. 99mTc(V)-DMSA is available at high pH (approximately 7.5) by adding NaHCO3 solution in the presence of a small amount of reducing agent (SnCl2). On the other hand, trivalent 99mTc-DMSA [99mTc(III)-DMSA] can be obtained at low pH (below 3) in the presence of an excess amount of reducing agent. In the clinical evaluation of a patient with a medullary carcinoma of the thyroid, only 99mTc(V)-DMSA revealed an area of intense accumulation.

Visualization of dopamine nerve terminals in monkey by positron emission tomography using 4-[18F]fluoro-L-m-tyrosine

4-[18F]Fluoro-L-m-tyrosine (FMT) is an L-Dopa analog that essentially follows the L-Dopa metabolic pathway, but without 3-O-methylation or extensive peripheral metabolism. As such, FMT may serve as a useful probe of striatal dopaminergic function with positron emission tomography (PET). FMT was synthesized, as previously described by Perlmutter et al. [Appl Radiat Isot 1990;41:801-807]. Scanning was undertaken with the SHR2000 positron tomograph (image spatial resolution, 3.5 x 4.5 x 6.5 mm). Two Macaca monkeys were anesthetized with ketamine (10 mg/kg) and pentobarbital (20 mg/kg). FMT was administered intravenously (5-6 mCi; specific activity 1-2 Ci/mmol) following carbidopa pretreatment (5 mg/kg i.v., 60 min before FMT administration). Dynamic image acquisition was done for 2 h immediately after tracer injection. This emission acquisition involved twelve 2-min frames followed by nine 4-min frames, and six 10-min images. Arterial blood samples were collected according to a schedule for assay of plasma [18F] radioactivity. Specific uptake of FMT in aromatic L-amino-acid-decarboxylase-rich areas of the monkey striatum was observed with PET imaging. The striatum-to-cerebellum ratio of the accumulation increased over time to 3.0 at 2 h. These results show the promise of FMT as a PET tracer in evaluating the CNS dopaminergic system.

Clinical evaluation of thallium-201 SPECT in supratentorial gliomas: relationship to histologic grade, prognosis and proliferative activities

We performed 201Tl SPECT and cell kinetic studies on 28 presurgical patients with supratentorial gliomas by administering bromodeoxyuridine (BUdR). All patients had surgery and had follow-up for more than 25 mo. In patients with grade IV glioma (198.1% +/- 32.8%, n = 10), the 201Tl index, expressed as the count rate of the tumor site to the count rate over the contralateral normal region, was significantly higher than that in patients with grade III glioma (140.5% +/- 15.1%, n = 4, p < 0.01) or low-grade glioma (104.1% +/- 22.6%, n = 14, p < 0.001). A significant correlation was observed between the 201Tl index and BUdR-positive cells in excised tumor specimens (r = 0.67, p < 0.001). The 201Tl index of the 12 patients who died was higher than those who survived (173.2% versus 122.4%, p < 0.01). These results show the clinical utility of 201Tl brain SPECT in imaging supratentorial glioma and that the 201Tl index is representative of proliferative activity of the tumor.

[Basic study of CA125 measurement using a newly developed "SD-8729" IRMA kit]

"SD-8729" is a one-step IRMA kit employing OC125 antibody as 125I-labeled tracer and M-11 antibody as an immunoadsorbent. Higher bound-radioactivity to beads was observed with shorter incubation time than that of a currently used CA125 IRMA kit which employed OC125 antibody both as 125I-labeled ligand and immunoadsorbent attached to beads. Almost identical CA125 values were obtained by using two kits. The antigenic nature recognized by the M-11 antibody seems substantially different from those of 130-22 or 145-9 antibodies recognizing CA130 antigen.

[Basic and clinical studies of serum CA195 antigen assay with "BL-CA195" kit]

We performed basic and clinical studies of IRMA "BL-CA195" kit in which monoclonal antibody CC3C195 was used as 125I-labeled tracer and solid phase antibody. The reproducibility of the assay results and dilution curves were satisfactory. There was a close correlation between serum CA195 and CA19-9 values, and many patients with pancreatic and colorectal cancer had elevated serum CA195 concentrations. Unlabeled CC3C195 antibody dose-dependently and completely inhibited the binding of 125I-labeled anti-CA19-9 antibody to its corresponding antigen. These findings suggest that CA195 and CA19-9 share common antigenic determinants.

[Basic study of CA549, a new tumor marker for breast cancer, and evaluation of its clinical usefulness]

We performed basic and clinical studies of IRMA kits for serum CA549 antigen and examined the immunological correlation between CA549 and CA15-3 antigens. Satisfactory results were obtained in the basic studies of CA549 assays, such as the reproducibility and the dilution test. Many patients with breast cancer had elevated serum CA549 concentrations and significant correlation was observed between serum CA549 and CA15-3 values. Anti-CA549 antibody completely inhibited the binding of 125I-labeled anti-CA15-3 antibody to its antigens. These results suggest that CA549 and CA15-3 antigens have similar immunological characteristics.

[Clinical evaluation of 99mTc ethyl cysteinate dimer SPECT in patients with spinocerebellar degeneration; comparison with cerebral blood flow determined by PET]

Technetium-99m ethyl cysteinate dimer (99mTc-ECD) is regarded as a promising radiopharmaceutical for imaging regional cerebral blood flow (rCBF). We evaluated 99mTc-ECD SPECT comparing with rCBF images obtained by PET in 12 patients with spinocerebellar degeneration (SCD). SPECT images of 99mTc-ECD demonstrated characteristic findings of decreased rCBF in bilateral cerebellar hemisphere and almost identical with PET rCBF images in all patients based on the visual inspection. Semiquantitative analysis by drawing 14 intracranial regions of interest on SPECT and PET images revealed linear correlation between 99mTc-ECD count and rCBF measured by PET even in relatively high rCBF regions. In summary, 99mTc-ECD is a promising tracer for evaluating rCBF in patients with SCD and distribution of it correlates well with rCBF measured by PET.