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1.
J Comput Assist Tomogr ; 44(1): 20-25, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939877

RESUMO

OBJECTIVES: The purpose of this study was to evaluate whether quantitative analysis of lower leg muscle enhancement measured from dynamic computed tomographic angiography (dyn-CTA) could be used for diagnosis of peripheral arterial occlusive disease. METHODS: Patients (N = 35) with known peripheral arterial occlusive disease underwent the dyn-CTA of calves first. Five minutes later, standard CTA of the peripheral runoff from the diaphragm to the toes was performed. A runoff score was assigned by radiologists as a reference standard for each of 4 lower leg artery segments. The lower leg muscle enhancement measured from the dyn-CTA was analyzed by using quantitative kinetic parameters, including initial enhancement (E1), peak enhancement (Epeak), and enhancement ratio (ER) calculated from average time attenuation curves. In addition, histogram of lower leg muscle enhancement was evaluated by using the first enhanced phase images. RESULTS: Lower extremities were diagnosed as a normal group (n = 22) with each vessel segment score equals to 1 or lower and runoff score, 7 or lower, and otherwise as an ischemia group (n = 48). Average ± SD E1 is 91.4% ± 8.5% and 82.3% ± 10.7%, Epeak is 122.7% ± 10.4% and 115.6% ± 11.1%, and ER is 0.75 ± 0.05 and 0.72 ± 0.09 for normal and ischemia group, respectively. Statistical analysis showed that average E1 and Epeak for the ischemia group were significantly lower (P < 0.05) than the normal group. The histogram analysis demonstrated that mean and median of muscle enhancement in the ischemia group were significantly smaller (P < 0.05), and coefficient of variation (CV) was significantly larger (P < 0.05) than the normal group. There were weak negative correlations (r = -0.42, P < 0.05) between runoff scores and E1 and Epeak, and weak positive correlation (r = 0.40, P < 0.05) between runoff scores and CV. The receiver operating characteristics analysis between the 2 groups had area under the curve of 0.77 and 0.76 for E1 and CV, respectively. CONCLUSIONS: Lower leg muscle enhancement measured from the dyn-CTA could be assessed quantitatively to assist diagnosis of ischemia in clinical practice.


Assuntos
Arteriopatias Oclusivas/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Extremidade Inferior/diagnóstico por imagem , Músculo Esquelético/diagnóstico por imagem , Doença Arterial Periférica/diagnóstico por imagem , Adulto , Idoso , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doses de Radiação
2.
Phys Med Biol ; 64(15): 155012, 2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31220816

RESUMO

The Tofts pharmacokinetic model requires multiple calculations for analysis of dynamic contrast enhanced (DCE) MRI. In addition, the Tofts model may not be appropriate for the prostate. This can result in error propagation that reduces the accuracy of pharmacokinetic measurements. In this study, we present a compact solution allowing estimation of physiological parameters K trans and v e from ultrafast DCE acquisitions, without fitting DCE-MRI data to the standard Tofts pharmacokinetic model. Since the standard Tofts model can be simplified to the Patlak model at early times when contrast efflux from the extravascular extracellular space back to plasma is negligible, K trans can be solved explicitly for a specific time. Further, v e can be estimated directly from the late steady-state signal using the derivative form of Tofts model. Ultrafast DCE-MRI data were acquired from 18 prostate cancer patients on a Philips Achieva 3T-TX scanner. Regions-of-interest (ROIs) for prostate cancer, normal tissue, gluteal muscle, and iliac artery were manually traced. The contrast media concentration as function of time was calculated over each ROI using gradient echo signal equation with pre-contrast tissue T1 values, and using the 'reference tissue' model with a linear approximation. There was strong correlation (r = 0.88-0.91, p  < 0.0001) between K trans extracted from the Tofts model and K trans estimated from the compact solution for prostate cancer and normal tissue. Additionally, there was moderate correlation (r = 0.65-0.73, p  < 0.0001) between extracted versus estimated v e. Bland-Altman analysis showed moderate to good agreement between physiological parameters extracted from the Tofts model and those estimated from the compact solution with absolute bias less than 0.20 min-1 and 0.10 for K trans and v e, respectively. The compact solution may decrease systematic errors and error propagation, and could increase the efficiency of clinical workflow. The compact solution requires high temporal resolution DCE-MRI due to the need to adequately sample the early phase of contrast media uptake.

3.
Tomography ; 5(2): 260-265, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31245547

RESUMO

Accurately measuring arterial input function (AIF) is essential for quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). We used the indicator dilution principle to evaluate the accuracy of AIF measured directly from an artery following a low-dose contrast media ultrafast DCE-MRI. In total, 15 patients with biopsy-confirmed localized prostate cancers were recruited. Cardiac MRI (CMRI) and ultrafast DCE-MRI were acquired on a Philips 3 T Ingenia scanner. The AIF was measured at iliac arties following injection of a low-dose (0.015 mmol/kg) gadolinium (Gd) contrast media. The cardiac output (CO) from CMRI (COCMRI) was calculated from the difference in ventricular volume at diastole and systole measured on the short axis of heart. The CO from DCE-MRI (CODCE) was also calculated from the AIF and dose of the contrast media used. A correlation test and Bland-Altman plot were used to compare COCMRI and CODCE. The average (±standard deviation [SD]) area under the curve measured directly from local AIF was 0.219 ± 0.07 mM·min. The average (±SD) COCMRI and CODCE were 6.52 ± 1.47 L/min and 6.88 ± 1.64 L/min, respectively. There was a strong positive correlation (r = 0.82, P < .01) and good agreement between COCMRI and CODCE. The CODCE is consistent with the reference standard COCMRI. This indicates that the AIF can be measured accurately from an artery with ultrafast DCE-MRI following injection of a low-dose contrast media.


Assuntos
Meios de Contraste/administração & dosagem , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Neoplasias da Próstata/diagnóstico por imagem , Idoso , Humanos , Técnicas de Diluição do Indicador , Masculino , Pessoa de Meia-Idade , Próstata/diagnóstico por imagem , Reprodutibilidade dos Testes
4.
AJR Am J Roentgenol ; 213(2): W66-W75, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31039019

RESUMO

OBJECTIVE. The purpose of this study was to develop a new quantitative image analysis tool for estimating the risk of cancer of the prostate by use of quantitative multiparametric MRI (mpMRI) metrics. MATERIALS AND METHODS. Thirty patients with biopsy-confirmed prostate cancer (PCa) who underwent preoperative 3-T mpMRI were included in the study. Quantitative mpMRI metrics-apparent diffusion coefficient (ADC), T2, and dynamic contrast-enhanced (DCE) signal enhancement rate (α)-were calculated on a voxel-by-voxel basis for the whole prostate and coregistered. A normalized risk value (0-100) for each mpMRI parameter was obtained, with high risk values associated with low T2 and ADC and high signal enhancement rate. The final risk score was calculated as a weighted sum of the risk scores (ADC, 40%; T2, 40%; DCE, 20%). Data from five patients were used as training set to find the threshold for predicting PCa. In the other 25 patients, any region with a minimum of 30 con-joint voxels (≈ 4.8 mm2) with final risk score above the threshold was considered positive for cancer. Lesion-based and sector-based analyses were performed by matching prostatectomyverified malignancy and PCa predicted with the risk analysis tool. RESULTS. The risk map tool had sensitivity of 76.6%, 89.2%, and 100% for detecting all lesions, clinically significant lesions (≥ Gleason 3 + 4), and index lesions, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value for PCa detection for all lesions in the sector-based analysis were 78.9%, 88.5%, 84.4%, and 84.1%, respectively, with an ROC AUC of 0.84. CONCLUSION. The risk analysis tool is effective for detecting clinically significant PCa with reasonable sensitivity and specificity in both peripheral and transition zones.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Neoplasias da Próstata/diagnóstico por imagem , Idoso , Biópsia , Meios de Contraste , Imagem de Difusão por Ressonância Magnética , Estudos de Viabilidade , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Prostatectomia , Neoplasias da Próstata/patologia , Neoplasias da Próstata/cirurgia , Estudos Retrospectivos , Medição de Risco , Sensibilidade e Especificidade
5.
Abdom Radiol (NY) ; 44(6): 2233-2243, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30955071

RESUMO

PURPOSE: This study investigates the multiparametric MRI (mpMRI) appearance of different types of benign prostatic hyperplasia (BPH) and whether quantitative mpMRI is effective in differentiating between prostate cancer (PCa) and BPH. MATERIALS AND METHODS: Patients (n = 60) with confirmed PCa underwent preoperative 3T MRI. T2-weighted, multi-echo T2-weighted, diffusion weighted and dynamic contrast enhanced images (DCE) were obtained prior to undergoing prostatectomy. PCa and BPH (cystic, glandular or stromal) were identified in the transition zone and matched with MRI. Quantitative mpMRI metrics: T2, ADC and DCE-MRI parameters using an empirical mathematical model were measured. RESULTS: ADC values were significantly lower (p < 0.001) in PCa compared to all BPH types and can differentiate between PCa and BPH with high accuracy (AUC = 0.87, p < 0.001). T2 values were significantly lower (p < 0.001) in PCa compared to cystic BPH only, while glandular (p = 0.27) and stromal BPH (p = 0.99) showed no significant difference from PCa. BPH mimics PCa in the transition zone on DCE-MRI evidenced by no significant difference between them. mpMRI values of glandular (ADC = 1.31 ± 0.22 µm2/ms, T2 = 115.7 ± 37.3 ms) and cystic BPH (ADC = 1.92 ± 0.43 µm2/ms, T2 = 242.8 ± 117.9 ms) are significantly different. There was no significant difference in ADC (p = 0.72) and T2 (p = 0.46) between glandular and stromal BPH. CONCLUSIONS: Multiparametric MRI and specifically quantitative ADC values can be used for differentiating PCa and BPH, improving PCa diagnosis in the transition zone. However, DCE-MRI metrics are not effective in distinguishing PCa and BPH. Glandular BPH are not hyperintense on ADC and T2 as previously thought and have similar quantitative mpMRI measurements to stromal BPH. Glandular and cystic BPH appear differently on mpMRI and are histologically different.

6.
Int J Biomed Imaging ; 2019: 5987425, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30792738

RESUMO

Breast cancer is a major cause of morbidity and mortality in Western women. Tumor neoangiogenesis, the formation of new blood vessels from pre-existing ones, may be used as a prognostic marker for cancer progression. Clinical practice uses dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) to detect cancers based on increased blood flow and capillary permeability. However, DCE-MRI requires repeated injections of contrast media. Therefore we explored the use of noninvasive time-of-flight (TOF) MR angiography for serial studies of mouse mammary glands to measure the number and size of arteries feeding mammary glands with and without cancer. Virgin female C3(1) SV40 TAg mice (n=9), aged 18-20 weeks, were imaged on a 9.4 Tesla small animal scanner. Multislice T2-weighted (T2W) images and TOF-MRI angiograms were acquired over inguinal mouse mammary glands. The data were analyzed to determine tumor burden in each mammary gland and the volume of arteries feeding each mammary gland. After in vivo MRI, inguinal mammary glands were excised and fixed in formalin for histology. TOF angiography detected arteries with a diameter as small as 0.1 mm feeding the mammary glands. A significant correlation (r=0.79; p< 0.0001) was found between tumor volume and the arterial blood volume measured in mammary glands. Mammary arterial blood volumes ranging from 0.08 mm3 to 3.81 mm3 were measured. Tumors and blood vessels found on in vivo T2W and TOF images, respectively, were confirmed with ex vivo histological images. These results demonstrate increased recruitment of arteries to mammary glands with cancer, likely associated with neoangiogenesis. Neoangiogenesis may be detected by TOF angiography without injection of contrast agents. This would be very useful in mouse models where repeat placement of I.V. lines is challenging. In addition, analogous methods could be tested in humans to evaluate the vasculature of suspicious lesions without using contrast agents.

7.
J Vasc Interv Radiol ; 30(2): 141-147.e1, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30611627

RESUMO

PURPOSE: To assess the safety of low-dose intra-arterial (IA) tirofiban bolus after unsuccessful mechanical thrombectomy in patients with ischemic stroke due to large artery occlusion in anterior cerebral circulation. MATERIALS AND METHODS: Patients with ischemic stroke who were treated with mechanical thrombectomy were enrolled in a multicenter registry. Low-dose tirofiban was injected into the residual arterial thrombus in patients after unsuccessful mechanical thrombectomy. The major safety measurement was defined as symptomatic intracranial hemorrhage (SICH). The functional outcome at 90 days was assessed with the modified Rankin Scale, and a score of 0-2 was defined as favorable. RESULTS: Of the 632 enrolled patients, 154 (24.4%) received IA tirofiban treatment. The SICH rate was 13.6% (21/154) in patients with tirofiban and 16.7% (80/478) in patients without tirofiban (P = .361). IA tirofiban was not associated with increased risk of SICH (odds ratio [OR], 0.69; 95% confidence interval [CI], 0.36-1.31; P = .26). IA tirofiban treatment did not increase the risk of mortality at 90 days of the index stroke (OR, 0.66; 95% CI, 0.36-1.31; P = .15). Patients with large artery atherosclerosis stroke who were treated with tirofiban were associated with decreased risk of death (OR, 11.3% vs 23.4%; P = .042) compared to patients who were not treated with tirofiban. CONCLUSIONS: Low-dose IA tirofiban administration may be relatively safe in patients with ischemic stroke after unsuccessful recanalization.


Assuntos
Isquemia Encefálica/terapia , Fibrinolíticos/administração & dosagem , Acidente Vascular Cerebral/terapia , Trombectomia/efeitos adversos , Terapia Trombolítica , Tirofibana/administração & dosagem , Idoso , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/mortalidade , Isquemia Encefálica/fisiopatologia , China , Feminino , Humanos , Injeções Intra-Arteriais , Hemorragias Intracranianas/induzido quimicamente , Masculino , Pessoa de Meia-Idade , Recuperação de Função Fisiológica , Sistema de Registros , Estudos Retrospectivos , Fatores de Risco , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/mortalidade , Acidente Vascular Cerebral/fisiopatologia , Trombectomia/mortalidade , Terapia Trombolítica/efeitos adversos , Terapia Trombolítica/mortalidade , Fatores de Tempo , Tirofibana/efeitos adversos , Resultado do Tratamento
8.
J Magn Reson Imaging ; 49(5): 1374-1380, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30291653

RESUMO

BACKGROUND: Focal laser ablation (FLA) is a minimally invasive thermal ablation, guided by MRI through an optical fiber, to induce coagulative necrosis in cancer. PURPOSE: To evaluate the feasibility of high spectral and spatial resolution imaging using multiecho gradient echo (MEGE) MRI for identification of ablation zones, after FLA of prostate cancers. STUDY TYPE: Prospective. POPULATION: Fourteen patients with biopsy-confirmed localized prostate cancers. FIELD STRENGTH/SEQUENCE: FLA was performed under monitored conscious sedation with a 1.5T MRI scanner. Axial MEGE images were acquired before and after the last FLA. Pre- and postcontrast enhanced T1 -weighted (pT1 W) images were acquired to assess the FLA zone as a reference standard. ASSESSMENT: The T 2 * maps and water resonance peak height (WPH) images were calculated from the MEGE data. Ablation area was outlined using an active contour method. The maximum ablation area and total ablation volume were calculated from T 2 * and WPH images, and compared with the sizes measured from pT1 W images. STATISTICAL TESTS: Nonparametric Kruskal-Wallis tests were performed to determine whether there was significant difference in calculated ablation areas and volumes between T 2 * , WPH, and pT1 W images. RESULTS: Average T 2 * (38.9 ± 14.1 msec) in the ablation area was significantly shorter (P = 0.03) than the preablation area T 2 * (57.8 ± 25.3 msec). The normalized WPH value over the ablation area (1.3 ± 0.6) was significantly decreased (P = 0.02) more than the preablation area (2.0 ± 0.9). The maximum ablation areas measured by T 2 * (295.7 ± 96.4 mm2 ), WPH (312.2 ± 63.0 mm2 ), and pT1 W (320.3 ± 82.9 mm2 ) images were all similar. Furthermore, there was no significant difference (P = 0.31) for measured ablation volumes 3310.5 ± 649.5, 3406.4 ± 684.9, and 3672.5 ± 832.4 mm3 between T 2 * , WPH, and pT1 W images, respectively. DATA CONCLUSION: T 2 * and WPH images provide acceptable measurements of ablation zones during FLA treatment of prostate cancers without the need for contrast agent injection. This might allow repeated assessment following each heating period so that subsequent ablations can be optimized. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;49:1374-1380.

9.
Chem Asian J ; 14(10): 1814-1822, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30536561

RESUMO

The ladder-type nonacyclic arene (bis(thieno[3,2-b]thieno)cyclopentafluorene (BTTF)) has been designed and synthesized through fusing thienothiophenes with the fluorene core from the synthon of dimethyl 9,9-dioctyl-2,7-bis(thieno[3,2-b]thiophen-2-yl)fluorene-3,6-dicarboxylate. With BTTF as the central donor unit, a novel acceptor-donor-acceptor (A-D-A) type non-fullerene small-molecule acceptor (BTTFIC) was prepared with 1,1-dicyanomethylene-3-indanones (IC) as the peripheral acceptor units. The energy level of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of BTTFIC locate at -5.56 and -3.95 eV, respectively, presenting a low optical band gap of 1.58 eV. Encouragingly, polymer solar cells based on the blends of BTTFIC with both the representative wide- and low-bandgap polymer donors (PBDB-T, 1.82 eV. PTB7-Th, 1.58 eV) offer power conversion efficiencies over 8 % (8.78±0.18 % for PBDB-T:BTTFIC and 8.18±0.29 % for PTB7-Th:BTTFIC). These results highlight the advantage of ladder-type BTTF on the preparation of nonfullerene acceptors with extended conjugated backbones.

10.
AJR Am J Roentgenol ; 211(3): 595-604, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29995499

RESUMO

OBJECTIVE: The purpose of this study is to describe the quantitative and qualitative findings of multiparametric prostate MRI performed after MRI-guided focal laser ablation of prostate cancer. MATERIALS AND METHODS: A total of 27 consenting patients met the study inclusion criteria, which included but were not limited to the presence of clinical category T1c-T2a prostate cancer with a Gleason score of 7 or less, having undergone prostate biopsy before and after focal laser ablation, and having undergone MRI before ablation, immediately after ablation, and 3 and 12 months after ablation. Signal changes were evaluated both qualitatively and quantitatively and were then correlated with the results of subsequent biopsy performed at 3 and 12 months after ablation. RESULTS: MRI performed immediately after ablation revealed a hypovascular defect in the ablation zone, with patchy or bandlike decreased T2 signal most commonly noted at 3 months (in 66.7% of ablated lesions) and T2 scarring observed in most lesions (66.7%) at 12 months. Patchy or bandlike decreased apparent diffusion coefficient signal and scarlike changes were most prevalent at 3 months after ablation (50.0% of lesions), and these features remained the most commonly observed findings at 12 months after ablation (27.8% of lesions). At 12 months after ablation, 10 patients were found to have recurrent tumor, with three patients found to have persistent cancer when biopsy was performed at the ablation site. All postablation biopsy cases with positive results showed suspicious T2 and apparent diffusion coefficient characteristics, which were considered to be a well-defined nodular intermediate signal on both of these sequences. Two of the patients for whom positive biopsy findings were noted had focal enhancement of the ablation zone. A significant reduction in the forward volume transfer constant after ablation was found at the ablation site on follow-up examination. CONCLUSION: Multiparametric MRI can reveal postablation changes in the prostate and can be a valuable tool for monitoring patients who have undergone MRI-guided focal laser ablation.


Assuntos
Terapia a Laser , Imagem por Ressonância Magnética Intervencionista , Imagem por Ressonância Magnética , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/cirurgia , Humanos , Biópsia Guiada por Imagem , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Neoplasia Residual , Estudos Prospectivos , Neoplasias da Próstata/patologia , Resultado do Tratamento
11.
Invest Radiol ; 53(10): 609-615, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29702525

RESUMO

OBJECTIVES: This study investigates whether administration of low doses of gadolinium-based contrast agent (GBCA) for dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) can be as effective as a standard dose in distinguishing prostate cancer (PCa) from benign tissue. In addition, we evaluated the combination of kinetic parameters from the low- and high-dose injection as a new diagnostic marker. MATERIALS AND METHODS: Patients (n = 17) with histologically confirmed PCa underwent preoperative 3 T MRI. Dynamic contrast-enhanced MRI images were acquired at 8.3-second temporal resolution with a low dose (0.015 mmol/kg) and close to the standard dose (0.085 mmol/kg) of gadobentate dimeglumine bolus injections. Low-dose images were acquired for 3.5 minutes, followed by a 5-minute gap before acquiring standard dose images for 8.3 minutes. The data were analyzed qualitatively to investigate whether lesions could be detected based on early focal enhancement and quantitatively by fitting signal intensity as a function of time with an empirical mathematical model to obtain a maximum enhancement projection (MEP) and signal enhancement rate (α). RESULTS: Both low- and standard-dose DCE-MRI showed similar sensitivity (13/26 = 50%) and lesion conspicuity score (4.0 ± 1.0 vs 4.2 ± 0.9; P = 0.317) for PCa diagnosis on qualitative analysis. Prostate cancer showed significantly increased α compared with benign tissue for low (9.98 ± 5.84 vs 5.12 ± 2.95 s) but not for standard (4.27 ± 2.20 vs 3.35 ± 1.48 s) dose. The ratio of low-dose α to standard-dose α was significantly greater (P = 0.02) for PCa (2.8 ± 2.3) than for normal prostate (1.6 ± 0.9), suggesting changes in water exchange and T2* effects associated with cancer. In addition, decreases in the percentage change in T1 relaxation rate as a function of increasing contrast media concentration (ie, the "saturation effect") can also contribute to the observed differences in high-dose and low-dose α. Area under the receiver operating characteristic curve for differentiating PCa from benign tissue using α was higher for low dose (0.769) compared with standard dose (0.625). There were no significant differences between MEP calculated for PCa and normal tissue at the low and standard doses. Moderate significant Pearson correlation for DCE parameters, MEP (r = 0.53) and α (r = 0.58), was found between low and standard doses of GBCA. CONCLUSIONS: These preliminary results suggest that DCE-MRI with a low GBCA dose distinguishes PCa from benign prostate tissue more effectively than does the standard GBCA dose, based on signal enhancement rate. Diagnostic accuracy is similar on qualitative assessment. Prostate cancer diagnosis may be feasible with DCE-MRI with low-dose GBCA. In addition, comparison of enhancement kinetics after low and high doses of contrast media may provide diagnostically useful information.


Assuntos
Meios de Contraste/administração & dosagem , Gadolínio/administração & dosagem , Aumento da Imagem/métodos , Imagem por Ressonância Magnética/métodos , Neoplasias da Próstata/diagnóstico por imagem , Adulto , Idoso , Estudos de Viabilidade , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Próstata/diagnóstico por imagem , Neoplasias da Próstata/patologia , Curva ROC
12.
Australas Phys Eng Sci Med ; 41(2): 507-518, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29569210

RESUMO

Due to large inter- and intra-patient variabilities of arterial input functions (AIFs), accurately modeling and using patient-specific AIF are very important for quantitative analysis of dynamic contrast enhanced MRI. Computer simulations were performed to evaluate and compare nine population AIF models with the Parker AIF used as 'gold standard'. The Parker AIF was calculated with a temporal resolution of 1.5 s, and then the other nine AIF models were used to fit the Parker AIF. A total of 100 randomly generated volume transfer constants (Ktrans) and distribution volumes (ve) were used to calculate the contrast agent concentration curves based on the Parker AIF and the extended Tofts model with blood plasma volume (vp) = 0.0, 0.01, 0.05 and 0.10. Subsequently, nine AIF models were used to fit these curves to extract physiological parameters (Ktrans, ve and vp). The agreements between generated and extracted Ktrans and ve values were evaluated using Bland-Altman analysis. The effects of the second pass of the Parker AIF model with and without adding Rician noise on extracted physiological parameters were evaluated by 1000 simulations using one of the nine mathematical AIF models closest to the Parker model with the smallest number of parameters. The results demonstrated that a six-parameter linear function plus bi-exponential function AIF model was almost equivalent to the Parker AIF and that the corresponding generated and extracted Ktrans and ve were in excellent agreements. The effects of the second pass of contrast agent circulation were small on extracted physiological parameters using the extended Tofts model, unless noise was added with signal to noise ratio less than 10 dB.


Assuntos
Algoritmos , Artérias/diagnóstico por imagem , Artérias/fisiologia , Simulação por Computador , Meios de Contraste/química , Imagem por Ressonância Magnética , Modelos Teóricos , Humanos , Razão Sinal-Ruído
13.
PLoS One ; 13(1): e0190929, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29324859

RESUMO

The effects of consumption of different diets on the fatty acid composition in the mammary glands of SV40 T-antigen (Tag) transgenic mice, a well-established model of human triple-negative breast cancer, were investigated with magnetic resonance spectroscopy and spectroscopic imaging. Female C3(1) SV40 Tag transgenic mice (n = 12) were divided into three groups at 4 weeks of age: low fat diet (LFD), high animal fat diet (HAFD), and high fructose diet (HFruD). MRI scans of mammary glands were acquired with a 9.4 T scanner after 8 weeks on the diet. 1H spectra were acquired using point resolved spectroscopy (PRESS) from two 1 mm3 boxes on each side of inguinal mammary gland with no cancers, lymph nodes, or lymph ducts. High spectral and spatial resolution (HiSS) images were also acquired from nine 1-mm slices. A combination of Gaussian and Lorentzian functions was used to fit the spectra. The percentages of poly-unsaturated fatty acids (PUFA), mono-unsaturated fatty acids (MUFA), and saturated fatty acids (SFA) were calculated from each fitted spectrum. Water and fat peak height images (maps) were generated from HiSS data. The results showed that HAFD mice had significantly lower PUFA than both LFD (p < 0.001) and HFruD (p < 0.01) mice. The mammary lipid quantity calculated from 1H spectra was much larger in HAFD mice than in LFD (p = 0.03) but similar to HFruD mice (p = 0.10). The average fat signal intensity over the mammary glands calculated from HiSS fat maps was ~60% higher in HAFD mice than in LFD (p = 0.04) mice. The mean or median of calculated parameters for the HFruD mice were between those for LFD and HAFD mice. Therefore, PRESS spectroscopy and HiSS MRI demonstrated water and fat composition changes in mammary glands due to a Western diet, which was low in potassium, high in sodium, animal fat, and simple carbohydrates. Measurements of PUFA with MRI could be used to evaluate cancer risk, improve cancer detection and diagnosis, and guide preventative therapy.


Assuntos
Dieta com Restrição de Gorduras , Dieta Hiperlipídica , Açúcares da Dieta , Ácidos Graxos/metabolismo , Glândulas Mamárias Animais/metabolismo , Espectroscopia de Prótons por Ressonância Magnética , Animais , Feminino , Frutose , Imagem por Ressonância Magnética , Glândulas Mamárias Animais/diagnóstico por imagem , Camundongos Transgênicos , Distribuição Aleatória
14.
Phys Med Biol ; 63(3): 03NT01, 2018 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-29300175

RESUMO

The purpose of this study was to evaluate the accuracy of arterial input functions (AIFs) measured from dynamic contrast enhanced (DCE) MRI following a low dose of contrast media injection. The AIFs measured from DCE computed tomography (CT) were used as 'gold standard'. A total of twenty patients received CT and MRI scans on the same day. Patients received 120 ml Iohexol in DCE-CT and a low dose of (0.015 mM kg-1) of gadobenate dimeglumine in DCE-MRI. The AIFs were measured in the iliac artery and normalized to the CT and MRI contrast agent doses. To correct for different temporal resolution and sampling periods of CT and MRI, an empirical mathematical model (EMM) was used to fit the AIFs first. Then numerical AIFs (AIFCT and AIFMRI) were calculated based on fitting parameters. The AIFMRI was convolved with a 'contrast agent injection' function ([Formula: see text]) to correct for the difference between MRI and CT contrast agent injection times (~1.5 s versus 30 s). The results show that the EMMs accurately fitted AIFs measured from CT and MRI. There was no significant difference (p > 0.05) between the maximum peak amplitude of AIFs from CT (22.1 ± 4.1 mM/dose) and MRI after convolution (22.3 ± 5.2 mM/dose). The shapes of the AIFCT and [Formula: see text] were very similar. Our results demonstrated that AIFs can be accurately measured by MRI following low dose contrast agent injection.


Assuntos
Algoritmos , Artérias/diagnóstico por imagem , Meios de Contraste , Processamento de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Neoplasias da Próstata/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Artérias/metabolismo , Artérias/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia
15.
Acad Radiol ; 25(3): 349-358, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29167070

RESUMO

RATIONALE AND OBJECTIVES: This study aimed to test high temporal resolution dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) for different zones of the prostate and evaluate its performance in the diagnosis of prostate cancer (PCa). Determine whether the addition of ultrafast DCE-MRI improves the performance of multiparametric MRI. MATERIALS AND METHODS: Patients (n = 20) with pathologically confirmed PCa underwent preoperative 3T MRI with T2-weighted, diffusion-weighted, and high temporal resolution (~2.2 seconds) DCE-MRI using gadoterate meglumine (Guerbet, Bloomington, IN) without an endorectal coil. DCE-MRI data were analyzed by fitting signal intensity with an empirical mathematical model to obtain parameters: percent signal enhancement, enhancement rate (α), washout rate (ß), initial enhancement slope, and enhancement start time along with apparent diffusion coefficient (ADC) and T2 values. Regions of interests were placed on sites of prostatectomy verified malignancy (n = 46) and normal tissue (n = 71) from different zones. RESULTS: Cancer (α = 6.45 ± 4.71 s-1, ß = 0.067 ± 0.042 s-1, slope = 3.78 ± 1.90 s-1) showed significantly (P <.05) faster signal enhancement and washout rates than normal tissue (α = 3.0 ± 2.1 s-1, ß = 0.034 ± 0.050 s-1, slope = 1.9 ± 1.4 s-1), but showed similar percentage signal enhancement and enhancement start time. Receiver operating characteristic analysis showed area under the curve for DCE parameters was comparable to ADC and T2 in the peripheral (DCE 0.67-0.82, ADC 0.80, T2 0.89) and transition zones (DCE 0.61-0.72, ADC 0.69, T2 0.75), but higher in the central zone (DCE 0.79-0.88, ADC 0.45, T2 0.45) and anterior fibromuscular stroma (DCE 0.86-0.89, ADC 0.35, T2 0.12). Importantly, combining DCE with ADC and T2 increased area under the curve by ~30%, further improving the diagnostic accuracy of PCa detection. CONCLUSION: Quantitative parameters from empirical mathematical model fits to ultrafast DCE-MRI improve diagnosis of PCa. DCE-MRI with higher temporal resolution may capture clinically useful information for PCa diagnosis that would be missed by low temporal resolution DCE-MRI. This new information could improve the performance of multiparametric MRI in PCa detection.


Assuntos
Imagem de Difusão por Ressonância Magnética , Neoplasias da Próstata/diagnóstico por imagem , Adulto , Idoso , Meios de Contraste , Humanos , Masculino , Meglumina , Pessoa de Meia-Idade , Compostos Organometálicos , Prostatectomia , Neoplasias da Próstata/patologia , Neoplasias da Próstata/cirurgia , Curva ROC
16.
Acta Cardiol ; : 1-7, 2017 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-29283315

RESUMO

BACKGROUND: Long-term exercise training may have negative effects on cardiovascular functions. Measurement and calculation of central hemodynamic parameters can comprehensively evaluate the cardiovascular functions. This study aims to compare the central hemodynamics between young basketball athletes and matched controls. METHODS: Total 19 young long-term trained male basketball athletes and 17 matched male recreationally active controls participated. The central hemodynamic parameters such as central blood pressure, pulse pressure, heart rate (HR), augmentation index normalised to 75 bpm (AIx@HR75), augmentation index (AIx), ejection duration (ED), sub-endocardial viability ratio (SEVR) were measured, and total peripheral resistance (TPR), stroke volume (SV) and cardiac output (CO) were calculated. Non-parameter tests and t-test were used to analyse the central hemodynamic parameters between athletes and controls. RESULTS: HR (56 ± 5 bpm versus 79 ± 9 bpm, p < .001), AIx@HR75 (-8 ± 10% versus -1 ± 10%, p < .05), ED (28 ± 2% versus 36 ± 3%, p < .001) and TPR (0.004 ± 0.006 mmHg s/mL versus 0.012 ± 0.006 mmHg s/mL, p < .001) were significantly lower in basketball athletes compared to the controls. SEVR (231 ± 32% versus 159 ± 21%, p < .001) and SV (154 ± 50 mL versus 101 ± 43 mL, p < .01) were significantly higher in basketball athletes than those in the controls. However, there were no significant differences in central blood pressure, pulse pressure, AIx and CO between them. CONCLUSIONS: There is no negative effect on central hemodynamics in young basketball athletes after long-term exercise training. The young basketball athletes have a higher myocardial perfusion, higher efficiency of blood supply, stronger vascular functions and better balance of myocardial oxygen of supply and demand than the controls in this central hemodynamic parameters analysis.

17.
Phys Med Biol ; 62(18): N445-N459, 2017 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-28786402

RESUMO

Differences between region-of-interest (ROI) and pixel-by-pixel analysis of dynamic contrast enhanced (DCE) MRI data were investigated in this study with computer simulations and pre-clinical experiments. ROIs were simulated with 10, 50, 100, 200, 400, and 800 different pixels. For each pixel, a contrast agent concentration as a function of time, C(t), was calculated using the Tofts DCE-MRI model with randomly generated physiological parameters (K trans and v e) and the Parker population arterial input function. The average C(t) for each ROI was calculated and then K trans and v e for the ROI was extracted. The simulations were run 100 times for each ROI with new K trans and v e generated. In addition, white Gaussian noise was added to C(t) with 3, 6, and 12 dB signal-to-noise ratios to each C(t). For pre-clinical experiments, Copenhagen rats (n = 6) with implanted prostate tumors in the hind limb were used in this study. The DCE-MRI data were acquired with a temporal resolution of ~5 s in a 4.7 T animal scanner, before, during, and after a bolus injection (<5 s) of Gd-DTPA for a total imaging duration of ~10 min. K trans and v e were calculated in two ways: (i) by fitting C(t) for each pixel, and then averaging the pixel values over the entire ROI, and (ii) by averaging C(t) over the entire ROI, and then fitting averaged C(t) to extract K trans and v e. The simulation results showed that in heterogeneous ROIs, the pixel-by-pixel averaged K trans was ~25% to ~50% larger (p < 0.01) than the ROI-averaged K trans. At higher noise levels, the pixel-averaged K trans was greater than the 'true' K trans, but the ROI-averaged K trans was lower than the 'true' K trans. The ROI-averaged K trans was closer to the true K trans than pixel-averaged K trans for high noise levels. In pre-clinical experiments, the pixel-by-pixel averaged K trans was ~15% larger than the ROI-averaged K trans. Overall, with the Tofts model, the extracted physiological parameters from the pixel-by-pixel averages were larger than the ROI averages. These differences were dependent on the heterogeneity of the ROI.


Assuntos
Algoritmos , Meios de Contraste/metabolismo , Imagem por Ressonância Magnética/métodos , Neoplasias da Próstata/patologia , Animais , Simulação por Computador , Gadolínio DTPA , Masculino , Neoplasias da Próstata/metabolismo , Ratos , Razão Sinal-Ruído
18.
Med Eng Phys ; 48: 142-149, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28690044

RESUMO

The purpose of this study was to analyze and compare a series of measured radial pulse waves as a function of contact pressure for young and old healthy volunteers, and old patients with cardiovascular disease. The radial pulse waves were detected with a pressure sensor and the contact pressure of the sensor was incremented by 20gf during the signal acquisition. A mathematical model of radial pulse waveform was developed by using two Gaussian functions modulated by radical functions and used to fit the pulse waveforms. Then, a ratio of area (rA) and a ratio of peak height (rPH) between percussion wave and dicrotic wave as a function of contact pressure were calculated based on fitted parameters. The results demonstrated that there was a maximum for waveform peak height, a minimum for rA (rAmin) and a minimum for rPH (rPHmin) appeared as contact pressure varied. On average, older patients had higher peak amplitude and a significantly smaller rAmin (p<0.001) and rPHmin (p<0.02) than the young and old volunteers. The rAmin and rPHmin calculated with the mathematical model had moderate to strong positive linear correlations (r=0.66 to 0.84, p<0.006) with those directly calculated without the model. The receiver operating characteristic (ROC) analysis showed that the rAmin calculated with the model and the contact pressure measured at the rAmin had good diagnostic accuracy to distinguish healthy volunteers vs. diseased patients. Therefore, using the mathematical model to quantitatively analyze the radial pulse waveforms as a function of contact pressure could be useful in the diagnosis of cardiovascular diseases.


Assuntos
Doenças Cardiovasculares/diagnóstico , Modelos Teóricos , Análise de Onda de Pulso , Punho , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças Cardiovasculares/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Pressão , Artéria Radial/fisiopatologia , Adulto Jovem
19.
NMR Biomed ; 30(10)2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28661075

RESUMO

High animal fat consumption is associated with an increase in triple-negative breast cancer (TNBC) risk. Based on previous MRI studies demonstrating the feasibility of detecting very early non-palpable mammary cancers in simian virus 40 large T antigen (SV40TAg) mice, we examined the effect of dietary fat fed from weaning to young adulthood in this model of TNBC. Virgin female C3(1)SV40TAg mice (n = 16) were weaned at 3-4 weeks of age and then fed either a low fat diet (LFD) (n = 8, 3.7 kcal/g; 17.2% kcal from vegetable oil) or a high animal fat diet (HAFD) (n = 8, 5.3 kcal/g; 60% kcal from lard). After 8 weeks on the diet (12 weeks of age), fast spin echo MR images of inguinal mammary glands were acquired at 9.4 T. Following in vivo MRI, mice were sacrificed and inguinal mammary glands were excised and formalin fixed for ex vivo MRI. 3D volume-rendered MR images were then correlated with mammary gland histology to assess the glandular parenchyma and tumor burden. Using in vivo MRI, an average of 3.88 ± 1.03 tumors were detected per HAFD-fed mouse compared with an average of 1.25 ± 1.16 per LFD-fed mouse (p < 0.007). Additionally, the average tumor volume was significantly higher following HAFD feeding (0.53 ± 0.45 mm3 ) compared with LFD feeding (0.20 ± 0.08 mm3 , p < 0.02). Analysis of ex vivo MR and histology images demonstrated that HAFD mouse mammary glands had denser parenchyma, irregular and enlarged ducts, dilated blood vessels, increased white adipose tissue, and increased tumor invasion. MRI and histological studies of the SV40TAg mice demonstrated that HAFD feeding also resulted in higher cancer incidence and larger mammary tumors. Unlike other imaging methods for assessing environmental effects on mammary cancer growth, MRI allows routine serial measurements and reliable detection of small cancers as well as accurate tumor volume measurements and assessment of the three-dimensional distribution of tumors over time.


Assuntos
Carcinogênese/patologia , Gorduras na Dieta/efeitos adversos , Imagem por Ressonância Magnética/métodos , Neoplasias Mamárias Animais/diagnóstico por imagem , Neoplasias de Mama Triplo Negativas/diagnóstico por imagem , Adiposidade , Animais , Modelos Animais de Doenças , Feminino , Glândulas Mamárias Animais/diagnóstico por imagem , Glândulas Mamárias Animais/patologia , Neoplasias Mamárias Animais/patologia , Camundongos , Neoplasias de Mama Triplo Negativas/patologia , Carga Tumoral , Desmame
20.
Magn Reson Imaging ; 40: 48-52, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28366759

RESUMO

High resolution 3D MRI was used to study contrast agent distribution and leakage in normal mouse mammary glands and glands containing in situ cancer after intra-ductal injection. Five female FVB/N mice (~19weeks old) with no detectable mammary cancer and eight C3(1) SV40 Tag virgin female mice (~15weeks old) with extensive in situ cancer were studied. A 34G, 45° tip Hamilton needle with a 25µL Hamilton syringe was inserted into the tip of the nipple and approximately 15µL of a Gadodiamide was injected slowly over 1min into the nipple and throughout the duct on one side of the inguinal gland. Following injection, the mouse was placed in a 9.4T MRI scanner, and a series of high resolution 3D T1-weighted images was acquired with a temporal resolution of 9.1min to follow contrast agent leakage from the ducts. The first image was acquired at about 12min after injection. Ductal enhancement regions detected in images acquired between 12 and 21min after contrast agent injection was five times smaller in SV40 mouse mammary ducts (p<0.001) than in non-cancerous FVB/N mouse mammary ducts, perhaps due to rapid washout of contrast agent from the SV40 ducts. The contrast agent washout rate measured between 12min and 90min after injection was ~20% faster (p<0.004) in SV40 mammary ducts than in FVB/N mammary ducts. These results may be due to higher permeability of the SV40 ducts, likely due to the presence of in situ cancers. Therefore, increased permeability of ducts may indicate early stage breast cancers.


Assuntos
Neoplasias da Mama/fisiopatologia , Meios de Contraste/química , Gadolínio DTPA/química , Imagem Tridimensional/métodos , Imagem por Ressonância Magnética/métodos , Animais , Mama , Feminino , Humanos , Injeções , Mamografia , Camundongos
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