In addition, compared to planar images, the SPECT method improves lesion contrast and anatomical clarity by the removal of superimposed radioactivity [ 38 ].
Mansberg et al. Similarly, Tehranipour et al. As such, a potential good response to therapy can be predicted. Conversely, a poor correlation could be due to small metastatic lesions undetectable in BS images because of an inherently low spatial resolution. Furthermore, the distribution of particles could be affected during intra-arterial injections by vessel selection, the flow in a selected vessel, or the size and amount of the injected particles.
Discordant findings can also be related to technical errors such as a superselective intra-arterial injection during the RE, or poor vascularized hepatic tumors, thereby leading to the accumulation of radiotracers in normal tissues [ 26 , 33 , 41 ].
In contrast to concordance cases, the therapeutic response will not be ideal in discordant cases because of inadequate radiation to the target [ 26 ]. We will, however, evaluate the clinical applications of the anticipated grading system in an ongoing study.
The potential advantage of 32 P scintigraphy is its ability to depict the vascularity of viable tumor cells rather than the necrotic tissue of a tumor mass Figure 5. Therefore, BS imaging of P after the RE of the hepatic tumors can be reflective of vascularized and viable tumoral tissues [ 33 ]. The extrahepatic deposition of radiotracers is an important finding, which can assist physicians in subsequent treatment planning.
The extrahepatic activity in the spleen Figure 4 , lung, and GI tract can have probable unwanted complications. In addition, because of the lower delivered radiation dose to the target, failure in the treatment can be predicted. Ahmadzadehfar et al. Sebastian et al. It should be mentioned that the current study had some limitations.
One of the most important drawbacks is its small sample size. Another limitation is that we did not perform an angiogram with Tc-MAA to rule out a possible high lung shunt; however, further evidence needs to be acquired.
Despite the shortcomings of BS imaging, good quality images can be obtained by the optimization of the energy window and collimator type.
BS imaging of 32 P, after the RE of hepatic tumors, can confirm the hepatic and extrahepatic distribution of radiotracers to predict the patient's response to RE therapy. The authors declare that there is no conflict of interests regarding the publication of this paper.
National Center for Biotechnology Information , U. Journal List Radiol Res Pract v. Radiol Res Pract. Published online Mar Author information Article notes Copyright and License information Disclaimer. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This article has been cited by other articles in PMC.
Abstract Background. Introduction Radioembolization RE is a promising therapeutic modality for patients with unresectable hepatic tumors. Materials and Methods A total of 39 patients with unresectable hepatic or metastatic tumors of any origin, which were candidates for RE [ 17 ] with 32 P particles, were included in this study. Anatomical Imaging Cross-sectional imaging with a CT or MRI was accomplished for all patients in order to determine the size and location of the lesions as numerical segments consistent with the physiological division of Couinaud [ 19 ].
Radioembolization Procedure The standard angiographic method for the assessment of the femoral artery was used [ 20 ]. Bremsstrahlung Imaging Imaging was conducted 24—72 hours after the RE of the hepatic tumors.
Results Thirty-nine patients with a variety of hepatic tumoral lesions were treated with RE and evaluated Table 1. Open in a separate window. Figure 1. Table 1 Characteristics of patients treated with RE. Figure 2. Figure 3. Figure 4. Figure 5. Conclusion Despite the shortcomings of BS imaging, good quality images can be obtained by the optimization of the energy window and collimator type. Conflict of Interests The authors declare that there is no conflict of interests regarding the publication of this paper.
References 1. Yttrium labelled resin microspheres for treatment of primary and secondary malignant liver tumors. Transcatheter intraarterial therapies: rationale and overview. EANM procedure guideline for the treatment of liver cancer and liver metastases with intra-arterial radioactive compounds. Dose delivery estimated by bremsstrahlung imaging and partition model correlated with response following intra-arterial radioembolization with 32p-glass microspheres for the treatment of hepatocellular carcinoma.
Journal of Gastrointestinal Surgery. Radioembolization of liver tumors with yttrium microspheres. Accumulation of the radiolabeled prophyrins in tumour is dependent on various parameters such as porphyrin structure, choice of radioisotope, pH, the presence of inflammation and many other factors. However, the balance between hydrophilicity and lipophilicity is also recognized as an important factor in tumour accumulation.
Whereas, lipophilicity of the agent plays an important role in tumor accumulation, hydrophilicity is a significant key in the clearance of the agent from the non-target organs. Therefore, a balance between these two properties is necessary for developing a suitable agent and for contributing to the challenge in designing suitable derivatives of porphyrin Das et al.
A novel Lu-labeled porphyrin for possible use in targeted tumor therapy. Due to these good physical characteristics as well as the feasibility of large-scale production in adequate specific activity and radionuclidic purity using a moderate flux reactor, Lu has been considered as a promising radionuclide for developing therapeutic radiopharmaceuticals due to its suitable half-life.
Peptide receptor therapies in neuroendocrine tumors. Preparation and preliminary biological evaluation of Lu-labeled hydroxyapatite as a promising agent for radiation synovectomy of small joints. Preparation and preliminary studies on Lu-labeled hydroxyapatite particles for possible use in the therapy of liver cancer. Porohyrins and metalloporphyrins. New York: Elsevier Science Publishing, TPPH 2 was investigated Figure 1. Figure 1. Structure of TPPH2. As for the amount of energy uptake in any organs by ionizing radiation, the absorbed dose, plays an important role in evaluating the risks associated with the administration of radiopharmaceuticals and thus the maximum amount of activity that should be undertaken Stabin et al.
Radiation dosimetry in nuclear medicine. MIRD primer for absorbed dose calculations. New York: Society of Nuclear Medicine, In this work, we endeavour to report, synthesis, radiolabeling, quality control and biodistribution studies of Lu-TPP in wild-type rats.
Also the partition coefficient of the complex was calculated and the absorbed dose to each organ of human was evaluated by biodistribution studies in rats by MIRD method. Chemicals were purchased from the Aldrich Chemical Co.
Infrared spectrum was measured on a Perkin-Elmer spectrometer by means of a KBr disc. Normal saline and sodium acetate used for labeling were of high purity and had been filtered through 0. Radionuclidic purity was checked with the same detector. All calculations as well as tissue count were based on the keV peak of Lu. The mixture was filtered through a 0. For radionuclidic purity determination, the sample was checked by gamma-ray spectroscopy on an HPGe detector for 5 h based on two major photons of Lu 6.
This compound was prepared according to the reported method using freshly distilled benzaldehyde, pyrrole and propionic acid followed by oxidation Adler et al. IR KBr , , , The final solution was then passed through a 0.
A mixture of 1 mLof 1-octanol and 1 mL of isotonic acetate-buffered saline pH 7 containing approximately 3. The reported log P values are the average of the second and third extractions from three to four independent measurements.
The stability of the complex was checked according to the conventional ITLC method. A sample of [ Lu]-TPP 37 MBq was kept at room temperature for 2 days while being checked by ITLC at time intervals in order to check stability in final product using above chromatography system.
For serum stability studies, to The distribution of Lucl 3 and the radiolabeled complex among tissues were determined for wild-type rats. The total amount of radioactivity injected into each rat was measured by counting the 1 mL syringe before and after injection in a dose calibrator with fixed geometry. The animals were sacrificed by CO 2 asphyxiation at selected times after injection 2, 4, 24, 48, and h.
The tissues blood, heart, lung, brain, intestine, feces, skin, stomach, kidneys, liver, muscle and bone were weighed and rinsed with normal saline and their specific activities were determined with an HPGe detector equipped with a sample holder device as percent of injected dose per gram of tissues.
The absorbed dose of each human organ was calculated by MIRD method based on biodistribution data in wild-type rats. The accumulated activity in animals was extrapolated to the accumulated activity in humans by the proposed method of Sparks et al. Comparison of the effectiveness of some common animal data scaling techniques in estimating human radiation dose Sixth International Radiopharmaceutical Dosimetry Symposium.
The accumulated source activity for each organ of animals was calculated by plotting the percentage-injected dose versus time for each organ and computing the area under the curves. For this purpose, the data points which represent the percentage-injected dose were created.
The curves were extrapolated to infinity by fitting the tail of each curve to a monoexponential curve with the exponential coefficient equal to physical decay constant of Lu. Then the area under the curve was calculated. In order to extrapolate this accumulated activity to human, the mean weights of each organ for standard human were used Table I. Thumbnail Table I. Jake R. University of Toronto.
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