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1.
J Cancer Res Ther ; 20(1): 281-284, 2024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-38554334

RESUMO

PURPOSE: To evaluate the effect of postoperative chemoradiotherapy (CRT) in patients with locally advanced gastric cancer (LAGC) who respond poorly to neoadjuvant chemotherapy (ChT). MATERIALS AND METHODS: The database of a tertiary medical center (2009-2020) was retrospectively reviewed for patients with LAGC in whom the initial treatment strategy consisted of perioperative ChT and surgery. Those who were subsequently referred for postoperative CRT because of a poor pathologic primary-tumor response (ypT3-4, ypN2-3, R1 resection) were selected for the study. CRT consisted of 45 Gy in 25 fractions of 1.8 Gy combined with capecitabine 825 mg/m2 twice daily on radiotherapy days or continuous infusion of 5-fluorouracil 180 mg/m2/day. RESULTS: The cohort included 26 patients of median age 61 years with LAGC (clinical stage IIA-III) after surgery with D1-D2 lymphadenectomy. R0 resection was achieved in 15 (58%). The pathological stage was III in 69% (IIA-IVA). Treatment was well tolerated. During a median follow-up time of 39 months, recurrences were documented in 14 patients (54%): 11 distant and 3 locoregional. Median progression-free survival was 23 months, and median overall survival was 65 months. Estimated 5-year survival rates were 42 and 54%, respectively. CONCLUSIONS: This small retrospective study suggests that in patients with LAGC who show a poor pathologic response to neoadjuvant ChT, a good outcome relative to reference arms in randomized trials can still be achieved with the addition of postoperative CRT. Further studies of the benefit of a tailored adaptive treatment approach to LAGC based on the response to neoadjuvant ChT are warranted.


Assuntos
Neoplasias Retais , Neoplasias Gástricas , Humanos , Pessoa de Meia-Idade , Terapia Neoadjuvante/efeitos adversos , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/patologia , Estudos Retrospectivos , Quimioterapia Adjuvante , Estadiamento de Neoplasias , Quimiorradioterapia/efeitos adversos , Fluoruracila , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Resultado do Tratamento , Neoplasias Retais/patologia
2.
J Neurooncol ; 166(3): 461-469, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38324192

RESUMO

INTRODUCTION: Historically, patients with brain metastasis (BM) have been excluded from clinical trials investigating treatments for non-small cell lung cancer (NSCLC) due to their unfavorable prognosis. Advanced treatments have increased survival prospects for NSCLC patients with BM. This study evaluated the life expectancy of NSCLC patients with and without BM in the context of contemporary treatments. METHODS: Outcome data were collected for patients with advanced NSCLC attending a tertiary medical center between 2015 and 2020. Patients were stratified according to BM status and compared for overall survival (OS) using log-rank and Cox regression analyses. RESULTS: The cohort included 360 patients with NSCLC of whom 134 (37.2%) had BM. Most (95%) of cases of BM developed within the first two years: 63% at diagnosis, 18% during the first year, 14% during the second year. There was no significant difference in OS between patients without BM and those with BM (median 23.7 vs. 22.3 months, HR = 0.97, p = 0.82); patients with BM and a targetable or non-targetable mutation (40.2 vs. 31.4 months, HR = 0.93, p = 0.84, and 20.7 vs. 19.87 months, HR = 0.95, p = 0.75, respectively); and patients with symptomatic BM (23.7 vs. 19.8 months, HR = 0.95, p = 0.78). Treatment for BM (95% of patients) consisted of stereotactic radiosurgery or tyrosine kinase inhibitors, with corresponding intracranial control rates of 90% and 86%. CONCLUSION: The results imply that the presence of BM has no impact on the prognosis of NSCLC. The practice of excluding NSCLC patients with BM from clinical trials warrants reconsideration.


Assuntos
Neoplasias Encefálicas , Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Prognóstico , Mutação , Neoplasias Encefálicas/genética , Estudos Retrospectivos
3.
J Nanotheranostics ; 3(4): 177-188, 2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36324626

RESUMO

Background: Glioblastoma is the most lethal primary brain malignancy in adults. Standard of care treatment, consisting of temozolomide (TMZ) and adjuvant radiotherapy (RT), mostly does not prevent local recurrence. The inability of drugs to enter the brain, in particular antibody-based drugs and radiosensitizers, is a crucial limitation to effective glioblastoma therapy. Methods: Here, we developed a combined strategy using radiosensitizer gold nanoparticles coated with insulin to cross the blood-brain barrier and shuttle tumor-targeting antibodies (cetuximab) into the brain. Results: Following intravenous injection to an orthotopic glioblastoma mouse model, the nanoparticles specifically accumulated within the tumor. Combining targeted nanoparticle injection with TMZ and RT standard of care significantly inhibited tumor growth and extended survival, as compared to standard of care alone. Histological analysis of tumors showed that the combined treatment eradicated tumor cells, and decreased tumor vascularization, proliferation, and repair. Conclusions: Our findings demonstrate radiosensitizer nanoparticles that effectively deliver antibodies into the brain, target the tumor, and effectively improve standard of care treatment outcome in glioblastoma.

4.
Harefuah ; 161(1): 55-60, 2022 Jan.
Artigo em Hebraico | MEDLINE | ID: mdl-35077062

RESUMO

INTRODUCTION: Ionizing radiation plays an important role in the treatment of patients with malignancy for cure and palliation. In the last decade there have been significant technological advances in radiation equipment, imaging and software. Owing to these developments, modern radiation is being shaped according to the size and form of the target organ and is accurate in locating the target location and can even take into account respiratory motion. Thanks to these developments, radiobiological concepts in radiation therapy have been tested and applied. Radiation doses have been increased to 5-20Gy/fraction and the number of treatments has been reduced to an average of five. This type of treatment is called Stereotactic Body Radiation Therapy (SBRT). The application of this treatment to various tumors may improve the effectiveness of radiation therapy, increasing local tumor control and reducing side effects. Another benefit is cutting the overall treatment time. The present article presents a review of literature on stereotactic radiation in lung tumors, prostate cancer, primary liver tumors and in oligo-metastases.


Assuntos
Neoplasias Pulmonares , Neoplasias da Próstata , Radiocirurgia , Humanos , Masculino , Cuidados Paliativos , Radiação Ionizante , Radiocirurgia/efeitos adversos
5.
J Clin Neurosci ; 85: 20-26, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33581785

RESUMO

Glioblastoma (GBM) typically presents as a single lesion. Multicentric GBM are defined as well separated lesions on MRI (enhancing and non-enhancing). Multicentric GBM with non-enhancing lesions (MNE-GBM) are rarely described in literature. We aimed at describing the radiologic characteristics, treatment, and clinical course of those patients. The institutional neuropathological database was searched for GBM patients diagnosed between 1/1/2015 and 31/05/2018. All pre-operative MRI brain scans were reviewed to identify patients with MNE-GBM. Electronic medical records and follow-up MRI scans were reviewed to assess progression-free survival (PFS) and overall survival (OS). Out of 149 adult patients with newly diagnosed GBM, 12 met the inclusion criteria of MNE-GBM, all of them presented at least one enhancing lesion. Median follow-up for the MNE-GBM patients was 16.1 months. At last follow-up, all patients had recurrence (median PFS 7.6 months) and eleven patients had deceased. Median OS was 16.2 months (95% CI, 4.1-27.5). Eleven patients received radiotherapy concomitant with temozolomide as initial treatment. Radiation field included all the disease foci (enhancing and non-enhancing lesions) in 8 patients, five of them progressed within the non-enhancing lesion. Three patients did not receive radiation for the entire non-enhancing lesions, and two of them progressed within the non-irradiated areas. In conclusion, MNE-GBM is not rare, and has high risk of aggressive progression within the separate non-enhancing lesion.


Assuntos
Neoplasias Encefálicas/patologia , Glioblastoma/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos Alquilantes/uso terapêutico , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/terapia , Quimiorradioterapia/métodos , Feminino , Glioblastoma/diagnóstico por imagem , Glioblastoma/terapia , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Intervalo Livre de Progressão , Estudos Retrospectivos , Temozolomida/uso terapêutico , Adulto Jovem
6.
J Oncol ; 2020: 1980891, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32963526

RESUMO

Central nervous system (CNS) metastases occur frequently in oncogene-driven non-small cell lung cancer (NSCLC). Standard treatment approaches can potentially delay systemic treatment (surgical intervention) or result in neurocognitive impairment (radiotherapy). Recently, next-generation tyrosine kinase inhibitors (TKIs) have demonstrated remarkable intracranial activity. However, most clinical trials did not enroll patients suffering neurological symptoms. Our study aimed to assess the CNS activity of targeted therapies in this patient population. We present a case series of nine NSCLC patients with either EGFR mutation or ALK rearrangement and symptomatic CNS metastases that were treated with TKIs. Clinicopathological characteristics, treatment, and outcomes were analyzed. Most patients presented with symptomatic CNS metastases at time of metastatic disease presentation (6/9). Additionally, the majority of patients had leptomeningeal disease (6/9) and multiple parenchymal metastases. Patients presented with a variety of CNS symptoms with the most common being nausea, vomiting, headache, and confusion. Most patients (6/9) responded rapidly both clinically and radiographically to the targeted treatment, with a marked correlation between systemic and intracranial radiographic response. In conclusion, upfront use of next-generation TKIs in patients with oncogene-driven NSCLC with symptomatic CNS metastases is associated with reasonable intracranial activity and represents a valuable treatment option.

7.
BMC Cancer ; 20(1): 786, 2020 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-32819306

RESUMO

BACKGROUND: Meningiomas are the most common primary central nervous system tumors. Potential risk factors include obesity, height, history of allergy/atopy, and autoimmune diseases, but findings are conflicting. This study sought to assess the role of the different risk factors in the development of meningioma in adolescents/young adults. METHODS: The cohort included 2,035,915 Jewish men and women who had undergone compulsory physical examination between 1967 and 2011, at age 16 to 19 years, prior to and independent of actual military enlistment. To determine the incidence of meningioma, the military database was matched with the Israel National Cancer Registry. Cox proportional hazard models were used to estimate the hazard ratios for meningioma according to sex, body mass index (BMI), height, and history of allergic or autoimmune disease. RESULTS: A total of 480 subjects (328 females) were diagnosed with meningioma during a follow-up of 40,304,078 person-years. Median age at diagnosis was 42.1 ± 9.4 years (range 17.4-62.6). On univariate analysis, female sex (p < 0.01) and height (p < 0.01) were associated with risk of meningioma. When the data were stratified by sex, height remained a significant factor only in men. Spline analysis of the male subjects showed that a height of 1.62 m was associated with a minimum disease risk and a height of 1.85+ meters, with a significant risk. CONCLUSIONS: This large population study showed that sex and adolescent height in males (> 1.85 m) were associated with an increased risk of meningioma in adulthood.


Assuntos
Estatura , Neoplasias Meníngeas/epidemiologia , Meningioma/epidemiologia , Adolescente , Adulto , Feminino , Seguimentos , Humanos , Incidência , Israel/epidemiologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sistema de Registros , Medição de Risco/estatística & dados numéricos , Fatores de Risco , Fatores Sexuais , Adulto Jovem
8.
Thorac Cancer ; 11(8): 2331-2334, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32548905

RESUMO

Anti-PD-1/PD-L1 agents play a crucial part in the treatment of non-small cell cancer (NSCLC) demonstrating improved overall response rate (ORR) and overall survival (OS). Recent studies evaluating combination treatment with anti-PD-1 and anti-CTLA-4 suggests improved outcome but also increased toxicity. Evidence is scarce regarding subsequent treatment with immune checkpoint inhibitors (ICPI) after progression on anti-PD-1/PD-L1. A total of 15 patients were treated with a combination of anti-PD1 agent and ipilimumab after confirmed progression of disease on anti-PD1/PDL1 alone during 2017. Clinical data were retrieved retrospectively. Disease control rate (DCR) was defined as partial response (PR) or stable disease (SD). The overall DCR was 33.3% (n = 5); two patients with PR and three patients with SD, three of whom had prior documented disease control on anti-PD1. The immune-related adverse event (irAE) rate was 40% (n = 6); two patients had grade 3 AE and one patient died of pneumonitis. While the median time to progression was two months (range 0.5-16), four of the five patients with PR/SD experienced durable benefit for 8-16 months. This small retrospective cohort of heavily pretreated unselected patients suggests ipilimumab might reboost the immune response in patients with advanced NSCLC following progression of disease on anti-PD1 therapy, while delaying exposure to the higher toxicity rates associated with upfront combination therapy. This strategy should be explored prospectively.


Assuntos
Antígeno B7-H1/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Ipilimumab/uso terapêutico , Neoplasias Pulmonares/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Antígeno B7-H1/farmacologia , Carcinoma Pulmonar de Células não Pequenas/mortalidade , Progressão da Doença , Feminino , Humanos , Ipilimumab/farmacologia , Neoplasias Pulmonares/mortalidade , Masculino , Pessoa de Meia-Idade , Análise de Sobrevida
9.
J Neurooncol ; 138(2): 315-320, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29429124

RESUMO

The increased survival of patients with gastroesophageal adenocarcinoma (GAD) following improvements in treatment has been accompanied by a rising incidence of secondary brain metastasis. HER2 amplification/overexpression, which has been associated with an increased risk of brain metastasis in breast cancer, is found in about 20% of patients with GAD. The aim of this study was to evaluate the effect of HER2 status on brain metastasis in GAD. The database of a tertiary cancer center was searched for patients with GAD diagnosed in 2011-2015, and data were collected on clinical characteristics, brain metastasis, HER2 status, and outcome. We identified 404 patients with a confirmed diagnosis of GAD. HER2 results were available for 298: 69 (23.2%) positive and 227 negative. Brain metastasis developed in 15 patients with GAD (3.7%); HER2 results, available in 13, were positive in 6, negative in 6, and equivocal in 1. The brain metastasis rate was significantly higher in HER2-positive than HER2-negative patients with GAD (6/69, 8.7% vs. 6/227, 2.6%; RR = 3.3, 95% CI 1.1-9.9, p = 0.034). Median overall survival from diagnosis of brain metastasis was 2.3 months, with no significant difference by HER2 status. HER2 positive GAD patients may be at increased risk to develop BM. Clinicians should maintain a lower threshold for performing brain imaging in patients with HER2-positive GAD given their increased risk of brain metastasis. The role of anti-HER2 agents in the development and treatment of brain metastasis in GAD warrants further study.


Assuntos
Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/secundário , Neoplasias Gastrointestinais/patologia , Receptor ErbB-2/metabolismo , Adenocarcinoma/epidemiologia , Adenocarcinoma/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/metabolismo , Neoplasias Encefálicas/epidemiologia , Neoplasias Encefálicas/terapia , Feminino , Neoplasias Gastrointestinais/epidemiologia , Neoplasias Gastrointestinais/metabolismo , Neoplasias Gastrointestinais/terapia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Análise de Sobrevida , Adulto Jovem
10.
Oncology ; 94(1): 31-38, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-28950265

RESUMO

OBJECTIVE: The number of older adults diagnosed with breast cancer is increasing. However, data on breast cancer characteristics, treatment, and survival in elderly women are sparse. METHODS: The database of a tertiary cancer center was searched for all women aged ≥65 years who were diagnosed with early breast cancer in 2004-2007. Patients were divided into 2 age groups: 65-75 years and >75 years. Data on tumor, treatment, and outcome parameters were compared. RESULTS: The cohort included 390 patients. The older group underwent more mastectomies but less axillary surgery or adjuvant systemic therapy. Median overall survival (OS) was 9.5 years in the older group and not reached in the younger group; the 8-year disease-free survival rates were 85 and 88%, respectively (p = 0.27). Both age and tumor subtype had an effect on OS and recurrence rates (p < 0.001 for OS; p = 0.16 for recurrence). The worst outcome was noted in women aged >75 years with triple-negative (TN) disease. CONCLUSION: The treatment approach was different between both age groups, despite similar tumor characteristics. TN subtype presented as the most aggressive disease in both age groups. Physicians should be alert to these findings and select treatment on a case-by-case basis.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/terapia , Idoso , Neoplasias da Mama/patologia , Terapia Combinada/métodos , Intervalo Livre de Doença , Feminino , Humanos , Mastectomia/métodos , Recidiva Local de Neoplasia/patologia , Estudos Retrospectivos , Resultado do Tratamento
11.
BMC Cancer ; 17(1): 624, 2017 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-28874120

RESUMO

BACKGROUND: Smoking is associated with an increased incidence of hormone receptor positive breast cancer. Data regarding worse breast cancer outcome in smokers are accumulating. Current literature regarding the impact of smoking on breast cancer characteristics is limited. We evaluated the impact of smoking on breast cancer characteristics and outcome. METHODS: This was a retrospective single center study. All women diagnosed from 4/2005 through 3/2012 and treated in our institute for early, estrogen receptor positive, human epidermal growth factor receptor 2 (HER2) negative breast cancer, whose tumors were sent for Oncotype DX analysis were included. Medical records were reviewed for demographics, clinico-pathological parameters, treatment and outcome. Data regarding smoking were retrieved according to patients' history at the first visit in the oncology clinic. Patients were grouped and compared according to smoking history (ever smokers vs. never smokers), smoking status (current vs. former and never smokers) and smoking intensity (pack years ≥30 vs. the rest of the cohort). Outcomes were adjusted in multivariate analyses and included age, menopausal status, ethnicity, tumor size, nodal status and grade. RESULTS: A total of 662 women were included. 28.2% had a history of smoking, 16.6% were current smokers and 11.3% were heavy smokers. Smoking had no impact on tumor size, nodal involvement and Oncotype DX recurrence score. Angiolymphatic and perineural invasion rates were higher in current smokers than in the rest of the cohort (10.4% vs. 5.1%, p = 0.045, 8.3% vs. 3.5%, p = 0.031, respectively). Smoking had no other impact on histological characteristics. Five-year disease free survival and overall survival rates were 95.7% and 98.5%, respectively. Smoking had no impact on outcomes. Adjusted disease free survival and overall survival did not influence the results. CONCLUSIONS: Smoking had no clinically significant influence on tumor characteristics and outcome among women with estrogen receptor positive, HER2 negative, early breast cancer. As the study was limited to a specific subgroup of the breast cancer population in this heterogeneous disease and since smoking is a modifiable risk factor for the disease, further research is required to clarify the possible impact of smoking on breast cancer.


Assuntos
Neoplasias da Mama/epidemiologia , Neoplasias da Mama/etiologia , Fumar , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/mortalidade , Neoplasias da Mama/patologia , Feminino , Humanos , Metástase Linfática , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Vigilância da População , Estudos Retrospectivos , Fumar/efeitos adversos , Resultado do Tratamento , Carga Tumoral
12.
J Exp Biol ; 218(Pt 2): 285-97, 2015 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-25609786

RESUMO

Cockroaches are remarkably stable runners, exhibiting rapid recovery from external perturbations. To uncover the mechanisms behind this important behavioral trait, we recorded leg kinematics of freely running animals in both undisturbed and perturbed trials. Functional coupling underlying inter-leg coordination was monitored before and during localized perturbations, which were applied to single legs via magnetic impulses. The resulting transient effects on all legs and the recovery times to normal pre-perturbation kinematics were studied. We estimated coupling architecture and strength by fitting experimental data to a six-leg-unit phase oscillator model. Using maximum-likelihood techniques, we found that a network with nearest-neighbor inter-leg coupling best fitted the data and that, although coupling strengths vary among preparations, the overall inputs entering each leg are approximately balanced and consistent. Simulations of models with different coupling strengths encountering perturbations suggest that the coupling schemes estimated from our experiments allow animals relatively fast and uniform recoveries from perturbations.


Assuntos
Baratas/fisiologia , Extremidades/fisiologia , Corrida , Animais , Fenômenos Biomecânicos
13.
Ophthalmic Plast Reconstr Surg ; 29(6): 437-9, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24192503

RESUMO

PURPOSE: Eye dominance and Hering's law dependence are postulated to influence eyelid position, and thus affect surgical outcomes following blepharoptosis surgery. Pseudoretraction of the contralateral eyelid, usually observed in the nondominant eye, is a well-recognized occurrence in the ophthalmic literature. In this article, these 2 phenomena were assessed preoperatively in blepharoptosis patients to evaluate their effect on postoperative outcomes. METHODS: In this retrospective cohort study, postoperative eyelid position and rates of reoperation were investigated in 38 patients with bilateral involutional ptosis, who underwent bilateral ptosis repair. Institutional Review Board approval was obtained. In addition to the standard ptosis preoperative evaluation, patients were tested for Hering's law dependence and eye dominance. RESULTS: None of the patients included in the study had significant postoperative eyelid asymmetry or required reoperation. CONCLUSIONS: Eye dominance and Hering's law dependence did not affect the surgical outcomes of the patients included in this study who had bilateral ptosis repair performed. It was postulated that this may be due to the balancing of these 2 factors intraoperatively, thus negating their effect on eyelid position postoperatively.


Assuntos
Blefaroptose/cirurgia , Dominância Ocular/fisiologia , Movimentos Oculares/fisiologia , Pálpebras/fisiologia , Idoso , Idoso de 80 Anos ou mais , Blefaroptose/fisiopatologia , Pálpebras/inervação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Procedimentos Cirúrgicos Oftalmológicos , Reoperação/estatística & dados numéricos , Estudos Retrospectivos
14.
Ultrasound Med Biol ; 35(5): 839-46, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19195769

RESUMO

The cornea's acoustic properties (speed-of-sound, backscatter, attenuation) are related to its state of hydration. Our aim was to determine these properties as a function of corneal hydration using high-frequency ultrasound. Bovine corneas were suspended in a Dexsol-equivalent corneal preservation medium at 33 degrees C and then immersed successively in 75%, 50% and 25% medium and distilled water. Using a 38-MHz focused ultrasound transducer, we measured speed-of-sound and corneal thickness (n = 8) and stromal backscatter (n = 6) after 45-min immersion in each medium. Corneal speed-of-sound was modeled as a function of corneal thickness. We found the mean speed-of-sound to be 1605.4 +/- 2.9 m/s in normotensive medium. The maximum observed speed-of-sound was 1616 m/s. As we decreased medium tonicity, the cornea swelled and the speed-of-sound decreased, reaching 1563.0 +/- 2.2 m/s in water. Average corneal thickness increased from 969 +/- 93 microm in 100% medium to 1579 +/- 104 microm in water. Going from 100% medium to water, stromal backscatter (midband-fit) increased from -60.0 +/- 0.8 dBr to -52.5 +/- 3.5 dBr, spectral slope increased from -0.119 +/- 0.021 to -0.005 +/- 0.030 dB/MHz and attenuation coefficient decreased from 0.927 +/- 0.434 to 0.010 +/- 0.581 dB/cm-MHz. The observed correlation between acoustic backscatter and attenuation with the speed-of-sound offers a potential means for more accurate determination of speed-of-sound and, hence, thickness in edematous corneas.


Assuntos
Córnea/diagnóstico por imagem , Edema da Córnea/diagnóstico por imagem , Animais , Água Corporal , Bovinos , Córnea/patologia , Edema da Córnea/patologia , Refração Ocular , Processamento de Sinais Assistido por Computador , Técnicas de Cultura de Tecidos , Ultrassonografia
15.
Ultrason Imaging ; 28(3): 179-88, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17147058

RESUMO

Very high frequency ultrasound (35-50 MHz) has had a significant impact upon clinical imaging of the anterior segment of the eye, offering an axial resolution as small as 30 microm. Higher frequencies, while potentially offering even finer resolution, are more affected by absorption in ocular tissues and even in the fluid coupling medium. Our aim was to develop and apply improved transducer technology utilizing frequencies beyond those routinely used for ultrasound biomicroscopy of the eye. A 75-MHz lithium niobate transducer with 2 mm aperture and 6 mm focal length was fabricated. We scanned the ciliary body and cornea of a human eye six years post-LASIK. Spectral parameter images were produced from the midband fit to local calibrated power spectra. Images were compared with those produced using a 35 MHz lithium niobate transducer of similar fractional bandwidth and focal ratio. The 75-MHz transducer was found to have a fractional bandwidth (-6 dB) of 61%. Images of the post-LASIK cornea showed higher stromal backscatter at 75 MHz than at 35 MHz. The improved lateral resolution resulted in better visualization of discontinuities in Bowman's layer, indicative of microfolds or breaks occurring at the time of surgery. The LASIK surface was evident as a discontinuity in stromal backscatter between the stromal component of the flap and the residual stroma. The iris and ciliary body were visualized despite attenuation by the overlying sclera. Very high frequency ultrasound imaging of the anterior segment of the eye has been restricted to the 35-50 MHz band for over a decade. We showed that higher frequencies can be used in vivo to image the cornea and anterior segment. This improvement in resolution and high sensitivity to backscatter from the corneal stroma will provide benefits in clinical diagnostic imaging of the anterior segment.


Assuntos
Corpo Ciliar/diagnóstico por imagem , Córnea/diagnóstico por imagem , Microscopia Acústica , Adulto , Desenho de Equipamento , Feminino , Humanos , Ceratomileuse Assistida por Excimer Laser In Situ , Transdutores
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