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1.
Artigo em Inglês | MEDLINE | ID: mdl-32296882

RESUMO

PURPOSE: The purpose of this study was to investigate the prognostic value of whole-body metabolic tumor volume (MTV) and other metabolic tumor parameters, obtained from baseline and first restaging 18F-FDG PET/CT scans in melanoma patients treated with immune checkpoint inhibitors (ICIs). METHODS: Eighty-five consecutive melanoma patients (M, 57; F, 28) treated with ICIs who underwent PET/CT scans before and approximately 3 months after the start of immunotherapy were retrospectively enrolled. Metabolic tumor parameters including MTV for all melanoma lesions were measured on each scan. A Cox proportional hazards model was used for univariate and multivariate analyses of metabolic parameters combined with known clinical prognostic factors associated with overall survival (OS). Kaplan-Meier curves for patients dichotomized based on median values of imaging parameters were generated. RESULTS: The median OS time in all patients was 45 months (95% CI 24-45 months). Univariate analysis demonstrated that MTV obtained from first restaging PET/CT scans (MTVpost) was the strongest prognostic factor for OS among PET/CT parameters (P < 0.0001). The median OS in patients with high MTVpost (≥ 23.44) was 16 months (95% CI 12-32 months) as compared with more than 60 months in patients with low MTVpost (< 23.44) (P = 0.0003). A multivariate model including PET/CT parameters and known clinical prognostic factors revealed that MTVpost and the presence of central nervous system lesions were independent prognostic factors for OS (P = 0.0004, 0.0167, respectively). One pseudoprogression case (1.2%) was seen in this population and classified into the high MTVpost group. CONCLUSION: Whole-body metabolic tumor volume from PET scan acquired approximately 3 months following initiation of immunotherapy (MTVpost) is a strong prognostic indicator of OS in melanoma patients. Although the possibility of pseudoprogression must be considered whenever evaluating first restaging PET imaging, it only occurred in 1 patient in our cohort.

2.
Clin Nucl Med ; 45(2): e88-e91, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31652159

RESUMO

F-FDG PET/CT for a 74-year-old man with elevated serum soluble interleukin 2 receptor showed multiple intense uptake in the liver, spleen, and bone. A surgical biopsy from 2 of liver tumors confirmed hepatosplenic αß T-cell lymphoma. One and a half months after biopsy, FDG PET scan was performed again for staging before starting chemotherapy, and it showed the complete disappearance of all of the lesions. The excisional biopsy could be a possible trigger of his spontaneous regression.


Assuntos
Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/cirurgia , Linfoma de Células T/patologia , Linfoma de Células T/cirurgia , Regressão Neoplásica Espontânea , Baço/patologia , Idoso , Biópsia , Fluordesoxiglucose F18 , Humanos , Neoplasias Hepáticas/diagnóstico por imagem , Linfoma de Células T/diagnóstico por imagem , Masculino , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons
3.
Ann Nucl Med ; 34(3): 182-191, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31820261

RESUMO

OBJECTIVE: False-positive bone lesions (bone pseudometastases) have been often reported in patients with esophageal cancer (EsoC). This study aimed to evaluate the vertebral 2-deoxy-2-[18F] fluoro-D-glucose (FDG) accumulation pattern in patients with newly diagnosed esophageal cancers and other malignancies (OtherT) to elucidate the possible mechanism that causes bone pseudometastasis. METHODS: FDG positron emission tomography/computed tomography performed for 90 patients with EsoC, and 112 patients with OtherT was retrospectively evaluated. The uptake pattern in the thoracic (Th) and lumbar (L) vertebrae was visually assessed regarding predominance (TL, Th ≒ L; Td, Th > L; Ld, L > Th), main intensity compared with the uptake in the blood pool (BP) (Grade 1 < BP, Grade 2 ≒ BP, or Grade 3 > BP), and homogeneity (homogeneous, heterogeneous, marginal, or spotty). The patterns between EsoC and OtherT and between Th and L were compared. RESULTS: TL, Td, and Ld patterns were observed in 51.1%, 48.9%, and 0% in EsoC and 79.7%, 20.3%, and 0% in OtherT. Though Grade 2 was most frequently observed in both groups, the ratio of Grade 3 in Th and Grade 1 in L was significantly higher in EsoC than in OtherT. Heterogeneous and spotty patterns were more frequently observed in L and in EsoC, and these were strongly associated with Td pattern. CONCLUSION: Td pattern was frequently seen, especially in EsoC, and was strongly associated with a heterogeneous or marginal pattern in the L. Heterogeneous marrow distribution with declined lumbar uptake is suspected as the mechanism of bone pseudometastasis.

4.
Mol Imaging Biol ; 22(2): 416, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31290051

RESUMO

This article was updated to correct the "greater than or equal to" (≥) symbols in Tables 4 and 5, which incorrectly appeared as "greater than" (>) symbols.

5.
Mol Imaging Biol ; 22(2): 407-415, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31222564

RESUMO

PURPOSE: A mobile positron emission tomography (PET) scanner called flexible PET (fxPET), designed to fit existing magnetic resonance imaging (MRI) or computed tomography (CT) system, has been developed. The purpose of this study was to evaluate the image quality, lesion detection rate, and quantitative values of fxPET compared with conventional bismuth germanium oxide (BGO)-based PET/CT without time-of-flight capability. PROCEDURES: Fifty-nine patients underwent whole-body (WB) PET/CT scans approximately 1 h after injection of 2-deoxy-2-[18F]fluoro-D-glucose, followed by the fxPET scans with detectors located above and below the patients (layout A) and with detectors closer to the patients (layout B). Two readers assessed the image quality using a 4-point grade for each layout and reached a consensus. We evaluated the differences and/or correlations between fxPET and WB PET/CT, including the lesion detection rates, the standardized uptake value (SUV), the metabolic tumor volume (MTV), the total lesion glycolysis (TLG), the tumor-to-normal liver ratio (TLR), and the background liver signal-to-noise ratio (SNR). RESULTS: The image quality of layout B was better than layout A (p < 0.0001). Of 184 lesions, the detection rate of layout B was significantly higher than WB PET/CT (p = 0.041), while the detection rate of layout A was comparable to WB PET/CT. The SUVmax/mean/peak were larger, and the MTVs were smaller in fxPET than WB PET/CT, especially in the lesions smaller than 2 cm (p < 0.01). The SUVmax/mean/peak, the MTVs and the TLGs of fxPET had significant positive correlations with WB PET/CT (p < 0.0001). The TLRs were significantly larger (p < 0.0001), but the background SNRs were significantly lower in fxPET than WB PET/CT (p < 0.05). CONCLUSIONS: The fxPET system yielded reasonable image quality and quantitative accuracy. Bringing the detectors closer to the patient yielded improved results.

6.
Clin Nucl Med ; 44(8): 634-642, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31274609

RESUMO

OBJECTIVES: We investigated clinical characteristics of patients with extremely increased or decreased physiologic F-FDG uptake of the liver and their prognosis. METHODS: One thousand four hundred eighty-seven PET/CT scans of patients with known or suspected malignancy were retrospectively analyzed. A spherical volume of interest (3 cm in diameter) was set on the right lobe of the liver to calculate the SUVmean. Scans with extremely high (SUVmean >97.5th percentile) and low (SUVmean <2.5th percentile) FDG uptake in the liver were evaluated. Physical and laboratory data among a control group (n = 30), the extremely high liver uptake group (HG, n = 36), and the extremely low liver uptake group (LG, n = 36) were compared. Overall survival (OS) of the 3 groups was also compared. RESULTS: Body weight and body mass index in the HG (SUVmean ≥3.04) were significantly higher than those in the control group. The LG cases (SUVmean ≤1.78) had anemia, impaired liver function, and systemic inflammation. They were also in a poor nutritional state. The characteristics of LG cases had many things in common with those of cachectic patients. Indeed, 36.1% of LG cases met the diagnostic criteria for cachexia. Moreover, in LG cases with viable and/or recurrent malignant lesions on FDG PET, the proportion of cachexia increased by 52.6%. The OS of LG cases (median, 33 months) was significantly worse than that of controls and HG cases. CONCLUSIONS: Our data indicate that cancer patients with extremely decreased liver FDG uptake were likely to have cancer cachexia and a lower OS.


Assuntos
Caquexia/complicações , Caquexia/diagnóstico por imagem , Fluordesoxiglucose F18/metabolismo , Fígado/diagnóstico por imagem , Fígado/metabolismo , Neoplasias/complicações , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Adulto , Idoso , Idoso de 80 Anos ou mais , Transporte Biológico , Caquexia/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Adulto Jovem
7.
Clin Nucl Med ; 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-31162266

RESUMO

OBJECTIVES: We investigated clinical characteristics of patients with extremely increased or decreased physiologic F-FDG uptake of the liver and their prognosis. METHODS: One thousand four hundred eighty-seven PET/CT scans of patients with known or suspected malignancy were retrospectively analyzed. A spherical volume of interest (3 cm in diameter) was set on the right lobe of the liver to calculate the SUVmean. Scans with extremely high (SUVmean >97.5th percentile) and low (SUVmean <2.5th percentile) FDG uptake in the liver were evaluated. Physical and laboratory data among a control group (n = 30), the extremely high liver uptake group (HG, n = 36), and the extremely low liver uptake group (LG, n = 36) were compared. Overall survival (OS) of the 3 groups was also compared. RESULTS: Body weight and body mass index in the HG (SUVmean ≥3.04) were significantly higher than those in the control group. The LG cases (SUVmean ≤1.78) had anemia, impaired liver function, and systemic inflammation. They were also in a poor nutritional state. The characteristics of LG cases had many things in common with those of cachectic patients. Indeed, 36.1% of LG cases met the diagnostic criteria for cachexia. Moreover, in LG cases with viable and/or recurrent malignant lesions on FDG PET, the proportion of cachexia increased by 52.6%. The OS of LG cases (median, 33 months) was significantly worse than that of controls and HG cases. CONCLUSIONS: Our data indicate that cancer patients with extremely decreased liver FDG uptake were likely to have cancer cachexia and a lower OS.

8.
Clin Nucl Med ; 44(10): 771-776, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31107756

RESUMO

PURPOSE OF THE REPORT: False-positive bone lesions mimicking bone metastases (bone pseudometastasis) on F-FDG PET/CT have often been reported in patients with esophageal cancer. We aimed to evaluate the prevalence and features of these lesions in Japanese patients with esophageal cancer. METHODS: In this retrospective study, we analyzed 83 FDG PET/CT studies for initial staging of esophageal cancer, and extracted patients with 1 or more localized high uptake sites with no subsequent progression, which were therefore judged to be bone pseudometastasis. The FDG PET/CT imaging features of the bone pseudometastasis were evaluated, and other available imaging and clinical features reviewed. RESULTS: Of the 83 patients, 7 had bone pseudometastasis. All 7 were males diagnosed with squamous cell cancer, of which 5 had T1a tumors. Bone pseudometastasis showed normal or ill-defined hyperdense (nonosteolytic) sites compared with the surrounding area on the CT. Additionally, accumulation in the upper vertebral levels of each case was contiguously high compared with the lumbar spines (we named this finding "contiguous accumulation"). On MRI, these findings were visualized as low signals on T1-weighted imaging (T1WI) and T2WI images but were unclear on fat-suppressed T2WI images. CONCLUSIONS: Among all PET/CT performed for staging of esophageal cancer, 8.3% demonstrated bone pseudometastasis characterized by heterogeneous distribution with severe fatty degeneration of bone marrow accompanied by contiguous accumulation. Caution is required during diagnoses of bone lesions in esophageal cancer patients in Japan to prevent inappropriate therapeutic choices.


Assuntos
Neoplasias Ósseas/secundário , Neoplasias Esofágicas/diagnóstico por imagem , Neoplasias Esofágicas/patologia , Fluordesoxiglucose F18 , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Idoso , Idoso de 80 Anos ou mais , Diagnóstico Diferencial , Reações Falso-Positivas , Feminino , Humanos , Japão , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
9.
Clin Nucl Med ; 44(5): e372-e374, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30888998

RESUMO

We report a case of splenic marginal zone B-cell lymphoma discovered in a 73-year-old man with cold agglutinin disease. PET/CT revealed splenomegaly with focally intense uptake of F-FDG and diffusely increased bone marrow uptake, which was considered to be secondary to hemolytic anemia. Splenectomy was performed. The histopathology of the spleen showed splenic marginal zone B-cell lymphoma with partial splenic infarction, which correlated with the area of focal intense FDG uptake. Depending on the time since onset, splenic infarctions can present as focal FDG accumulation.


Assuntos
Anemia Hemolítica Autoimune/diagnóstico por imagem , Linfoma de Zona Marginal Tipo Células B/diagnóstico por imagem , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Infarto do Baço/diagnóstico por imagem , Neoplasias Esplênicas/diagnóstico por imagem , Idoso , Anemia Hemolítica Autoimune/complicações , Fluordesoxiglucose F18 , Humanos , Linfoma de Zona Marginal Tipo Células B/complicações , Masculino , Compostos Radiofarmacêuticos , Neoplasias Esplênicas/complicações
10.
J Nucl Med ; 59(5): 846-851, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29097407

RESUMO

The current study tested a newly developed flexible PET (fxPET) scanner prototype. This fxPET system involves dual arc-shaped detectors based on silicon photomultipliers that are designed to fit existing MRI devices, allowing us to obtain fused PET and MR images by sequential PET and MR scanning. This prospective study sought to evaluate the image quality, lesion detection rate, and quantitative values of fxPET in comparison with conventional whole-body (WB) PET and to assess the accuracy of registration. Methods: Seventeen patients with suspected or known malignant tumors were analyzed. Approximately 1 h after intravenous injection of 18F-FDG, WB PET/CT was performed, followed by fxPET and MRI. For reconstruction of fxPET images, MRI-based attenuation correction was applied. The quality of fxPET images was visually assessed, and the number of detected lesions was compared between the 2 imaging methods. SUVmax and maximum average SUV within a 1 cm3 spheric volume (SUVpeak) of lesions were also compared. In addition, the magnitude of misregistration between fxPET and MR images was evaluated. Results: The image quality of fxPET was acceptable for diagnosis of malignant tumors. There was no significant difference in detectability of malignant lesions between fxPET and WB PET (P > 0.05). However, the fxPET system did not exhibit superior performance to the WB PET system. There were strong positive correlations between the 2 imaging modalities in SUVmax (ρ = 0.88) and SUVpeak (ρ = 0.81). SUVmax and SUVpeak measured with fxPET were approximately 1.1-fold greater than measured with WB PET. The average misregistration between fxPET and MR images was 5.5 ± 3.4 mm. Conclusion: Our preliminary data indicate that running an fxPET scanner near an existing MRI system provides visually and quantitatively acceptable fused PET/MR images for diagnosis of malignant lesions.


Assuntos
Imagem por Ressonância Magnética , Neoplasias/diagnóstico por imagem , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Tomografia por Emissão de Pósitrons/instrumentação , Adulto , Idoso , Feminino , Fluordesoxiglucose F18 , Humanos , Injeções Intravenosas , Masculino , Pessoa de Meia-Idade , Neoplasias/patologia , Projetos Piloto , Estudos Prospectivos , Compostos Radiofarmacêuticos , Tomografia Computadorizada por Raios X , Imagem Corporal Total
11.
Nucl Med Commun ; 38(5): 388-395, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28306620

RESUMO

BACKGROUND: A dedicated breast PET scanner with C-shaped detectors (C scanner) has been newly developed. The purpose of this study was to re-evaluate the diagnostic performance of high-resolution PET images with the new reconstruction conditions, obtained using this C scanner in breast cancer patients, and to compare the standardized uptake values (SUVs) of lesions obtained from the C scanner with those from whole-body PET/computed tomography (CT) (WB PET/CT). PATIENTS AND METHODS: A total of 159 female patients with known or suspected breast carcinomas (total 188 lesions: 172 invasive carcinomas; eight noninvasive ductal carcinomas in situ; eight benign lesions) were analysed. All patients underwent a WB PET/CT scan 1 h after the injection of fluorine-18 fluorodeoxyglucose, followed by breast scanning using the C scanner. Attenuation-corrected and scatter-corrected images were reconstructed with new parameters. RESULTS: Using the C scanner, 146 of 180 malignant lesions including five ductal carcinomas in situ were detected, 11 lesions were not detected, and the remaining 23 lesions were outside the field of view. The lesion-based sensitivity of the C scanner was 81.1%, and this was increased to 93.0% after excluding lesions outside the field of view; the sensitivity of WB PET/CT was 90.4%. The average maximum SUV of lesions obtained using the C scanner was 9.8±7.0, which was ∼1.6-fold larger than that obtained using WB PET/CT (6.1±4.2). CONCLUSION: There was no significant difference in breast cancer detectability in this population. The C scanner demonstrated ∼1.6-fold larger maximum SUV than WB PET/CT.


Assuntos
Tomografia Computadorizada com Tomografia por Emissão de Pósitrons/instrumentação , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/diagnóstico por imagem , Feminino , Humanos , Pessoa de Meia-Idade , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons/normas , Padrões de Referência , Imagem Corporal Total
12.
Clin Nucl Med ; 42(2): 157-160, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27922872

RESUMO

We report a case of anti-N-methyl-D-aspartate-receptor (anti-NMDAR) encephalitis associated with an immature teratoma developed in a 38-year-old woman. Positron emission tomography (PET) revealed focal intense uptake of F-fluorodeoxyglucose in an area of the brain corresponding to the right medial temporal lobe as well as an intrapelvic tumor. After the PET examination, the patient complained of disorientation and short-term memory loss. The ovarian tumor was resected and diagnosed as an immature teratoma. The cerebrospinal fluid analysis was positive for anti-NMDAR antibody. After surgery, the patient's neurologic symptoms improved. The PET finding of encephalitis associated with an immature teratoma was unexpected.


Assuntos
Encefalite Antirreceptor de N-Metil-D-Aspartato/diagnóstico por imagem , Neoplasias Ovarianas/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Teratoma/diagnóstico por imagem , Adulto , Encefalite Antirreceptor de N-Metil-D-Aspartato/complicações , Feminino , Fluordesoxiglucose F18 , Humanos , Neoplasias Ovarianas/complicações , Neoplasias Ovarianas/patologia , Compostos Radiofarmacêuticos , Teratoma/complicações , Teratoma/patologia
13.
Clin Nucl Med ; 41(11): e465-e472, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27607159

RESUMO

PURPOSE: This retrospective study compared the diagnostic performances of quantitative versus visual analyses of I-MIBG scintigraphy in patients with suspected pheochromocytoma and paraganglioma (PPGL). MATERIALS AND METHODS: SPECT images were obtained 6 and/or 24 h after MIBG injection from 68 patients with clinically suspected PPGL, with attenuation correction by low-dose unenhanced CT. Planar images were also obtained at each time point. SUVs of retroperitoneal tumors, including PPGLs, and physiological uptake by normal organs were measured using the SPECT images. The diagnostic performance of the quantitative assessment in differentiating PPGLs from other lesions or normal adrenal glands was assessed using receiver operating characteristic analysis. The planar scans and 6-h and 24-h SPECT/CT images were also assessed visually. RESULTS: PPGLs showed a significantly higher SUVmax (mean ± SD = 9.97 ± 3.86) than other retroperitoneal lesions (3.85 ± 1.51) or normal adrenal glands (3.91 ± 1.20). At an optimal cut-off of 6.57, the sensitivity, specificity, and accuracy of the quantitative assessment for 6-h SPECT/CT in differentiating PPGLs was 78.6%, 96.3%, and 92.6%, respectively; the area under the curve was 0.878. The diagnostic performance did not significantly differ between the quantitative and visual analyses, but the specificity of the former tended to be higher at 6 h (96.3% vs. 90.7%) and at 24 h (91.2% vs. 82.4%). CONCLUSIONS: The specificity, but not the sensitivity, of the quantitative approach was higher than that of visual assessment in differentiating PPGLs from other retroperitoneal pathologies and from physiological uptake in the normal adrenal gland.


Assuntos
Neoplasias das Glândulas Suprarrenais/diagnóstico por imagem , Glândulas Suprarrenais/diagnóstico por imagem , Neoplasias da Orelha/diagnóstico por imagem , Paraganglioma/diagnóstico por imagem , Feocromocitoma/diagnóstico por imagem , Neoplasias Retroperitoneais/diagnóstico por imagem , Neoplasias da Bexiga Urinária/diagnóstico por imagem , 3-Iodobenzilguanidina , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Curva ROC , Cintilografia , Compostos Radiofarmacêuticos , Estudos Retrospectivos , Sensibilidade e Especificidade , Tomografia Computadorizada com Tomografia Computadorizada de Emissão de Fóton Único , Tomografia Computadorizada de Emissão de Fóton Único , Adulto Jovem
14.
Conf Proc IEEE Eng Med Biol Soc ; 2011: 5589-92, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22255606

RESUMO

We have previously reported our attempts to control microbubbles (microcapsules) behavior in flow by primary Bjerknes force to increase the local concentration of the bubbles at a diseased part. However, there was a limitation in efficiency to propel bubbles of µm-order size. Thus we consider that forming aggregates of bubbles is effective to be propelled before entering into an ultrasound field by making use of secondary Bjerknes force under continuous ultrasound exposure. In this study, we observed the phenomena of aggregates formation by confirming variation of diameter and density of aggregates under various conditions of ultrasound exposure. Then we elucidated frequency dependence of the size of aggregates of micro-bubbles.


Assuntos
Coloides/química , Coloides/efeitos da radiação , Compostos Férricos/química , Compostos Férricos/efeitos da radiação , Ferro/química , Ferro/efeitos da radiação , Microbolhas , Óxidos/química , Óxidos/efeitos da radiação , Sonicação/métodos , Difusão/efeitos da radiação , Relação Dose-Resposta à Radiação , Teste de Materiais , Movimento (Física) , Doses de Radiação
15.
Artigo em Inglês | MEDLINE | ID: mdl-21096532

RESUMO

We have already reported our attempt to constrain direction of microcapsules in flow owing to an acoustic radiation force. However, the diameter of capsules was too large not to be applied in vivo. Furthermore, acoustic radiation force affected only in focal area because focused ultrasound was used. Thus we have improved our experiment by using microcapsules as small as blood cells and introducing a plane wave of ultrasound. We prepared an artificial blood vessel including a Y-form bifurcation established two observation areas. Then we newly defined the induction index to evaluate the difference of capsule density in two paths of downstream. As the result, optimum angle of ultrasound emission to induce to desired path was derived. And the induction index increased in proportion to the central frequency of ultrasound, which is affected by forming aggregation of capsules to receive more radiation force.


Assuntos
Vasos Sanguíneos/fisiologia , Cápsulas/química , Sistemas de Liberação de Medicamentos/métodos , Modelos Cardiovasculares , Ultrassonografia/métodos , Algoritmos , Difusão , Humanos , Microbolhas
16.
Artigo em Inglês | MEDLINE | ID: mdl-19963959

RESUMO

Micrometer-sized microcapsules collapse upon exposure to ultrasound. Use of this phenomenon for a drug delivery system (DDS), not only for local delivery of medication but also for gene therapy, should be possible. However, enhancing the efficiency of medication is limited because capsules in suspension diffuse in the human body after injection, since the motion of capsules in blood flow cannot be controlled. To control the behavior of microcapsules, acoustic radiation force was introduced. We detected local changes in microcapsule density by producing acoustic radiation force in an artificial blood vessel. Furthermore, we theoretically estimated the conditions required for active path selection of capsules at a bifurcation point in the artificial blood vessel. We observed the difference in capsule density at both in the bifurcation point and in alternative paths downstream of the bifurcation point for different the acoustic radiation forces. Also we confirmed the microcapsules are trapped against flow with the condition when the acoustic radiation force is more than fluid resistance of the capsules. The possibility of controlling capsule flow towards a specific point in a blood vessel was demonstrated.


Assuntos
Vasos Sanguíneos/efeitos da radiação , Cápsulas/efeitos da radiação , Composição de Medicamentos/métodos , Sonicação/métodos , Animais , Relação Dose-Resposta à Radiação , Humanos , Teste de Materiais , Doses de Radiação
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