-72.6%, -36.2%, 78.4%, and 69.2% (p = 0.003, p = 0.097, p = 0.073, and p = 0.180 in Figure 2), wh... more -72.6%, -36.2%, 78.4%, and 69.2% (p = 0.003, p = 0.097, p = 0.073, and p = 0.180 in Figure 2), while the mean percentage change in lesion size in FU-1 study was -9.7% (+8.8% ~ -32.5%) (p = 0.042). There were no significant correlation between change in tCho in FU-1 and the change in lesion size in FU-2 (r 2 = 0.06, p = 0.536). After completing the F/U-2 study, 3 (27%) of 11 patients did have positive tCho based on the criterion (i.e., tCho CRLB < 30%). The mean percentage change tCho, H2O, CH2, and CH3 after FU-2 study was -96.6%, 76.9%, 119.6%, and 119.5% (p = 0.004, p = 0.044, p = 0.008, and p = 0.005 in Figure 2), while the mean percentage change in lesion size in FU-2 study was 56.7% (-22.7% ~ -100%) (p = 0.007). Discussion The measured tCho levels at the baseline from 9 spectra were in a range of 0.19 – 5.29 (mean ± SD, 1.94 ± 1.76 mmol/kg). Our study showed the reduction in tCho at the first and second follow-up was significantly higher compared with the reduction in the tumor size (mean percentage change -72.6% vs. -9.7%, p < 0.0001; -96.6% vs. -56.7%, p < 0.003). The result demonstrates that the metabolic changes were greater than the tumor size changes, suggesting that they might have occurred before gross morphological changes. An early reduction of tCho can be interpreted as reflecting the inhibition of cellular proliferation and the cytotoxic effect of chemotherapy. In addition, the reduction in H2O and H2O/CH3 were also significantly higher than the reduction in tumor size at FU-1 (-36.2% vs. -9.7%, p = 0.028; -43.2% vs. -9.7%, p = 0.033), but not significant at FU-2 ((-76.9% vs. -61.1%, p = 0.125; -82.3% vs. -61.1%, p = 0.120). Our finding suggests that a greater reduction in tCho and H2O/CH3 at the FU-1 may help to predict a final (or, pathological) complete response. Therefore, we demonstrates that in vivo quantitative 1 H-MRS without water–fat
ABSTRACT We have introduced a NIR swept source based diffuse optical tomography (DOT) system. We ... more ABSTRACT We have introduced a NIR swept source based diffuse optical tomography (DOT) system. We also demonstrate the capabilities of the NIR swept laser for multi-spectral DOT application with a turbid gelatin phantom measurement.
A significant increase in electrical conductivity of neoplasticities compared to healthy tissues ... more A significant increase in electrical conductivity of neoplasticities compared to healthy tissues and benign formations has been reported in several studies. We previously reported preliminary results with MR based Electrical Impedance Tomography (MREIT) on several phantoms and a single animal. In the presented study, we applied the technique on ten tumor-bearing rats and collected MREIT images to investigate the potential of MREIT for characterizing malignant tumors. Results show that the tumors had significantly higher mean conductivity compared to the mean of conductivity in the rest of the body. Although heterogeneity of conductivity was observed in the tumor, the mean was still higher than the background.
A new technique for generating spatially resolved pressure-gradient images of flow fields is intr... more A new technique for generating spatially resolved pressure-gradient images of flow fields is introduced.
The bootstrap theory is applied to the case of pairing vibrations; an approximation used by Dang ... more The bootstrap theory is applied to the case of pairing vibrations; an approximation used by Dang and Klein in their treatment of pairing is shown to be consistent with the bootstrap theory. A modified Tamm-Dancoff approximation is described. The numerical results for Ni58,60,62 are compared with the exact solutions and with the results of Dang and Klein.
In recent years the contrast ratio (CR) has played an important role in the quantitation of imagi... more In recent years the contrast ratio (CR) has played an important role in the quantitation of imaging performance of X-ray image intensifiers. In practice, one uses either a lead disc or strip for measurement of contrast ratios. A theoretical relationship relating contrast ratios measured by both disc and strip techniques is discussed and experimental results are presented. The theoretical analysis uses the point spread function model to describe veiling glare for an image intensifier. It has been shown that one can predict strip contrast ratios after a determination of the veiling glare point spread function from a measurement of disc contrast ratios.
Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can ... more Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this study, we investigate the performance of a frequency-domain FT system for small inclusions that are embedded in a heterogeneous background. The results demonstrate that functional and structural a priori information is crucial to be able to recover both parameters with high accuracy. The functional a priori information is defined by the absorption and scattering maps at both excitation and emission wavelengths. Similarly, the boundaries of the small inclusion and different regions in the background are utilized as the structural a priori information. Without a priori information, the fluorophore concentration of a 5 mm inclusion in a 40 mm medium is recovered with 50% error, while the lifetime cannot be recovered at all. On the other hand, when both functional and structural information are available, the true lifetime can be recovered and the fluorophore concentration can be estimated only with 5% error. This study shows that a hybrid system that can acquire diffuse optical absorption tomography (DOT), FT and anatomical images in the same setting is essential to be able to recover the fluorophore concentration and lifetime accurately in vivo.
The brains of patients with Alzheimer&amp;amp;#39;s disease (AD) invariably exhibit neuropath... more The brains of patients with Alzheimer&amp;amp;#39;s disease (AD) invariably exhibit neuropathology in the hippocampus and entorhinal cortex when examined postmortem. Magnetic resonance imaging (MRI) offers a noninvasive, high-resolution method for quantifying volumetric changes in the AD brain antemortem. Eight patients diagnosed with probable AD and 7 age-matched controls had MRI scans and were tested on a battery of cognitive and olfactory tests. The hippocampus and entorhinal cortex (parahippocampal gyrus) showed significant atrophy, with over 40% reduction in size. Areas of the brain that are not highly involved in the degenerative state of AD, such as the striatum, did not show significant volumetric changes. Hippocampal and parahippocampal gyrus volumes had the highest correlation with scores on the Mini-Mental State Examination (r = 0.89), with lower correlations for a smell identification test (r = 0.65), odor match-to-sample test (r = 0.72), and a visual match-to-sample test (r = 0.26).
PurposeTo investigate the association between parameters obtained from dynamic contrast enhanced ... more PurposeTo investigate the association between parameters obtained from dynamic contrast enhanced MRI (DCE‐MRI) of breast cancer using different analysis approaches, as well as their correlation with angiogenesis biomarkers (vascular endothelial growth factor and vessel density).Materials and MethodsDCE‐MRI results were obtained from 105 patients with breast cancer (108 lesions). Three analysis methods were applied: 1) whole tumor analysis, 2) regional hot‐spot analysis, and 3) intratumor pixel‐by‐pixel analysis. Early enhancement intensities and fitted pharmacokinetic parameters were studied. Paraffin blocks of 71 surgically resected specimens were analyzed by immunohistochemical staining to measure microvessel counts (with CD31) and vascular endothelial growth factor (VEGF) expression levels.ResultsMRI parameters obtained from the three analysis methods showed significant correlations (P < 0.0001), but a substantial dispersion from the linear regression line was noted (r = 0.72–...
Artificial Cells, Blood Substitutes, and Biotechnology, 1994
The purpose of this study was to confirm the relationship of T1 and T2 relaxation rate vs. pO2 in... more The purpose of this study was to confirm the relationship of T1 and T2 relaxation rate vs. pO2 in vivo of 19F MR signal measured from intracellular perflubron. Our work to date has demonstrated that 1/T2 is more sensitive to pO2 than 1/T1 in the in vitro environment. The advantage of 1/T2 vs. 1/T1 is the speed of measurement and sensitivity. Seven alternating T1 and T2 measurements were obtained during a continuous acquisition using the TTISS pulse sequence. An abscess model was used for the in vivo experiments where rabbits were infused with 5ml/kg Oxygent HT 10 days prior to scanning. The abscess model was used because it has been shown that perflubron accumulates in macrophages located in the abscess wall. This technique thus provided signal from the intracellular milieu. The results of this study proved that pO2 monitoring by measuring T2 of 19F is feasible and can be used in-lieu of the T1 measurement. Given that the T2 measurement is much more rapid than the T1 measurement and that T2 changes are more sensitive than T1 changes with alterations in pO2, T2 should prove to be practical and useful for monitoring transient rapid changes in pO2.
-72.6%, -36.2%, 78.4%, and 69.2% (p = 0.003, p = 0.097, p = 0.073, and p = 0.180 in Figure 2), wh... more -72.6%, -36.2%, 78.4%, and 69.2% (p = 0.003, p = 0.097, p = 0.073, and p = 0.180 in Figure 2), while the mean percentage change in lesion size in FU-1 study was -9.7% (+8.8% ~ -32.5%) (p = 0.042). There were no significant correlation between change in tCho in FU-1 and the change in lesion size in FU-2 (r 2 = 0.06, p = 0.536). After completing the F/U-2 study, 3 (27%) of 11 patients did have positive tCho based on the criterion (i.e., tCho CRLB < 30%). The mean percentage change tCho, H2O, CH2, and CH3 after FU-2 study was -96.6%, 76.9%, 119.6%, and 119.5% (p = 0.004, p = 0.044, p = 0.008, and p = 0.005 in Figure 2), while the mean percentage change in lesion size in FU-2 study was 56.7% (-22.7% ~ -100%) (p = 0.007). Discussion The measured tCho levels at the baseline from 9 spectra were in a range of 0.19 – 5.29 (mean ± SD, 1.94 ± 1.76 mmol/kg). Our study showed the reduction in tCho at the first and second follow-up was significantly higher compared with the reduction in the tumor size (mean percentage change -72.6% vs. -9.7%, p < 0.0001; -96.6% vs. -56.7%, p < 0.003). The result demonstrates that the metabolic changes were greater than the tumor size changes, suggesting that they might have occurred before gross morphological changes. An early reduction of tCho can be interpreted as reflecting the inhibition of cellular proliferation and the cytotoxic effect of chemotherapy. In addition, the reduction in H2O and H2O/CH3 were also significantly higher than the reduction in tumor size at FU-1 (-36.2% vs. -9.7%, p = 0.028; -43.2% vs. -9.7%, p = 0.033), but not significant at FU-2 ((-76.9% vs. -61.1%, p = 0.125; -82.3% vs. -61.1%, p = 0.120). Our finding suggests that a greater reduction in tCho and H2O/CH3 at the FU-1 may help to predict a final (or, pathological) complete response. Therefore, we demonstrates that in vivo quantitative 1 H-MRS without water–fat
ABSTRACT We have introduced a NIR swept source based diffuse optical tomography (DOT) system. We ... more ABSTRACT We have introduced a NIR swept source based diffuse optical tomography (DOT) system. We also demonstrate the capabilities of the NIR swept laser for multi-spectral DOT application with a turbid gelatin phantom measurement.
A significant increase in electrical conductivity of neoplasticities compared to healthy tissues ... more A significant increase in electrical conductivity of neoplasticities compared to healthy tissues and benign formations has been reported in several studies. We previously reported preliminary results with MR based Electrical Impedance Tomography (MREIT) on several phantoms and a single animal. In the presented study, we applied the technique on ten tumor-bearing rats and collected MREIT images to investigate the potential of MREIT for characterizing malignant tumors. Results show that the tumors had significantly higher mean conductivity compared to the mean of conductivity in the rest of the body. Although heterogeneity of conductivity was observed in the tumor, the mean was still higher than the background.
A new technique for generating spatially resolved pressure-gradient images of flow fields is intr... more A new technique for generating spatially resolved pressure-gradient images of flow fields is introduced.
The bootstrap theory is applied to the case of pairing vibrations; an approximation used by Dang ... more The bootstrap theory is applied to the case of pairing vibrations; an approximation used by Dang and Klein in their treatment of pairing is shown to be consistent with the bootstrap theory. A modified Tamm-Dancoff approximation is described. The numerical results for Ni58,60,62 are compared with the exact solutions and with the results of Dang and Klein.
In recent years the contrast ratio (CR) has played an important role in the quantitation of imagi... more In recent years the contrast ratio (CR) has played an important role in the quantitation of imaging performance of X-ray image intensifiers. In practice, one uses either a lead disc or strip for measurement of contrast ratios. A theoretical relationship relating contrast ratios measured by both disc and strip techniques is discussed and experimental results are presented. The theoretical analysis uses the point spread function model to describe veiling glare for an image intensifier. It has been shown that one can predict strip contrast ratios after a determination of the veiling glare point spread function from a measurement of disc contrast ratios.
Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can ... more Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this study, we investigate the performance of a frequency-domain FT system for small inclusions that are embedded in a heterogeneous background. The results demonstrate that functional and structural a priori information is crucial to be able to recover both parameters with high accuracy. The functional a priori information is defined by the absorption and scattering maps at both excitation and emission wavelengths. Similarly, the boundaries of the small inclusion and different regions in the background are utilized as the structural a priori information. Without a priori information, the fluorophore concentration of a 5 mm inclusion in a 40 mm medium is recovered with 50% error, while the lifetime cannot be recovered at all. On the other hand, when both functional and structural information are available, the true lifetime can be recovered and the fluorophore concentration can be estimated only with 5% error. This study shows that a hybrid system that can acquire diffuse optical absorption tomography (DOT), FT and anatomical images in the same setting is essential to be able to recover the fluorophore concentration and lifetime accurately in vivo.
The brains of patients with Alzheimer&amp;amp;#39;s disease (AD) invariably exhibit neuropath... more The brains of patients with Alzheimer&amp;amp;#39;s disease (AD) invariably exhibit neuropathology in the hippocampus and entorhinal cortex when examined postmortem. Magnetic resonance imaging (MRI) offers a noninvasive, high-resolution method for quantifying volumetric changes in the AD brain antemortem. Eight patients diagnosed with probable AD and 7 age-matched controls had MRI scans and were tested on a battery of cognitive and olfactory tests. The hippocampus and entorhinal cortex (parahippocampal gyrus) showed significant atrophy, with over 40% reduction in size. Areas of the brain that are not highly involved in the degenerative state of AD, such as the striatum, did not show significant volumetric changes. Hippocampal and parahippocampal gyrus volumes had the highest correlation with scores on the Mini-Mental State Examination (r = 0.89), with lower correlations for a smell identification test (r = 0.65), odor match-to-sample test (r = 0.72), and a visual match-to-sample test (r = 0.26).
PurposeTo investigate the association between parameters obtained from dynamic contrast enhanced ... more PurposeTo investigate the association between parameters obtained from dynamic contrast enhanced MRI (DCE‐MRI) of breast cancer using different analysis approaches, as well as their correlation with angiogenesis biomarkers (vascular endothelial growth factor and vessel density).Materials and MethodsDCE‐MRI results were obtained from 105 patients with breast cancer (108 lesions). Three analysis methods were applied: 1) whole tumor analysis, 2) regional hot‐spot analysis, and 3) intratumor pixel‐by‐pixel analysis. Early enhancement intensities and fitted pharmacokinetic parameters were studied. Paraffin blocks of 71 surgically resected specimens were analyzed by immunohistochemical staining to measure microvessel counts (with CD31) and vascular endothelial growth factor (VEGF) expression levels.ResultsMRI parameters obtained from the three analysis methods showed significant correlations (P < 0.0001), but a substantial dispersion from the linear regression line was noted (r = 0.72–...
Artificial Cells, Blood Substitutes, and Biotechnology, 1994
The purpose of this study was to confirm the relationship of T1 and T2 relaxation rate vs. pO2 in... more The purpose of this study was to confirm the relationship of T1 and T2 relaxation rate vs. pO2 in vivo of 19F MR signal measured from intracellular perflubron. Our work to date has demonstrated that 1/T2 is more sensitive to pO2 than 1/T1 in the in vitro environment. The advantage of 1/T2 vs. 1/T1 is the speed of measurement and sensitivity. Seven alternating T1 and T2 measurements were obtained during a continuous acquisition using the TTISS pulse sequence. An abscess model was used for the in vivo experiments where rabbits were infused with 5ml/kg Oxygent HT 10 days prior to scanning. The abscess model was used because it has been shown that perflubron accumulates in macrophages located in the abscess wall. This technique thus provided signal from the intracellular milieu. The results of this study proved that pO2 monitoring by measuring T2 of 19F is feasible and can be used in-lieu of the T1 measurement. Given that the T2 measurement is much more rapid than the T1 measurement and that T2 changes are more sensitive than T1 changes with alterations in pO2, T2 should prove to be practical and useful for monitoring transient rapid changes in pO2.
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