Tissue Regions Of Interest Research Articles

Pathology-Driven Comprehensive Proteomic Profiling of the Prostate Cancer Tumor Microenvironment

Prostate cancer is the second most common cancer in men worldwide. Gleason grading is an important predictor of prostate cancer outcomes and is influential in determining patient treatment options. Clinical decisions based on a Gleason score of 7 are difficult as the prognosis for individuals diagnosed with Gleason 4+3 cancer is much worse than for those diagnosed with Gleason 3+4 cancer. Laser capture microdissection (LCM) is a highly precise method to isolate specific cell populations or discrete microregions from tissues. This report undertook a detailed molecular characterization of the tumor microenvironment in prostate cancer to define the proteome in the epithelial and stromal regions from tumor foci of Gleason grades 3 and 4. Tissue regions of interest were isolated from several Gleason 3+3 and Gleason 4+4 tumors using telepathology to leverage specialized pathology expertise to support LCM. Over 2,000 proteins were identified following liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of all regions of interest. Statistical analysis revealed significant differences in protein expression (>100 proteins) between Gleason 3 and Gleason 4 regions-in both stromal and epithelial compartments. A subset of these proteins has had prior strong association with prostate cancer, thereby providing evidence for the authenticity of the approach. Finally, validation of these proteins by immunohistochemistry has been obtained using an independent cohort of prostate cancer tumor specimens.Implications: This unbiased strategy provides a strong foundation for the development of biomarker protein panels with significant diagnostic and prognostic potential. Mol Cancer Res; 15(3); 281-93. ©2017 AACR.

N-glycan MALDI Imaging Mass Spectrometry on Formalin-Fixed Paraffin-Embedded Tissue Enables the Delineation of Ovarian Cancer Tissues

Ovarian cancer is a fatal gynaecological malignancy in adult women with a five-year overall survival rate of only 30%. Glycomic and glycoproteomic profiling studies have reported extensive protein glycosylation pattern alterations in ovarian cancer. Therefore, spatio-temporal investigation of these glycosylation changes may unearth tissue-specific changes that occur in the development and progression of ovarian cancer. A novel method for investigating tissue-specific N-linked glycans is using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) on formalin-fixed paraffin-embedded (FFPE) tissue sections that can spatially profile N-glycan compositions released from proteins in tissue-specific regions. In this study, tissue regions of interest (e.g. tumor, stroma, adipose tissue and necrotic areas) were isolated from FFPE tissue sections of advanced serous ovarian cancers (n = 3). PGC-LC-ESI-MS/MS and MALDI-MSI were used as complementary techniques to firstly generate structural information on the tissue-specific glycans in order to then obtain high resolution images of the glycan structure distribution in ovarian cancer tissue. The N-linked glycan repertoires carried by the proteins in these tissue regions were structurally characterized for the first time in FFPE ovarian cancer tissue regions, using enzymatic peptide-N-glycosidase F (PNGase F) release of N-glycans. The released glycans were analyzed by porous graphitized carbon liquid chromatography (PGC-LC) and collision induced electrospray negative mode MS fragmentation analysis. The N-glycan profiles identified by this analysis were then used to determine the location and distribution of each N-glycan on FFPE ovarian cancer sections that were treated with PNGase F using high resolution MALDI-MSI. A tissue-specific distribution of N-glycan structures identified particular regions of the ovarian cancer sections. For example, high mannose glycans were predominantly expressed in the tumor tissue region whereas complex/hybrid N-glycans were significantly abundant in the intervening stroma. Therefore, tumor and non-tumor tissue regions were clearly demarcated solely on their N-glycan structure distributions.

Erratum: Wangerin et al. (2015)

Prior reports have suggested that delayed 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) oncology imaging can improve the contrast-to-noise ratio (CNR) for known lesions. Our goal was to estimaterealistic bounds for lesion detectability for static measurements within 1 to 4 hours between FDG injectionand image acquisition. Tumor and normal tissue kinetic model parameters were estimated from dynamic PETstudies of patients with early-stage breast cancer. These parameters were used to generate time-activitycurves (TACs) for up to 4 hours, for which we assumed both nonreversible and reversible models with differ-ent rates of FDG dephosphorylation (k4). For each pair of tumor and normal tissue TACs, 600 PET sinogramrealizations were generated, and images were reconstructed using the ordered subsets expectation maximi-zation reconstruction algorithm. Test statistics for each tumor and normal tissue region of interest were outputfrom the computer model observers and evaluated using a receiver operating characteristic analysis, with thecalculated area under the curve (AUC) providing a measure of lesion detectability. For the nonreversiblemodel (k4 = 0), the AUC increased in 11 of 23 (48%) patients for 1 to 2 hours after the current standardpostradiotracer injection imaging window of 1 hour. This improvement was driven by increased tumor/nor-mal tissue contrast before the impact of increased noise that resulted from radiotracer decay began to domi-nate the imaging signal. Ask4was increased from 0 to 0.01 min−1, the time of maximum detectabilityshifted earlier, due to decreasing FDG concentration in the tumor lowering the CNR. These results imply thatdelayed PET imaging may reveal inconspicuous lesions that otherwise would have gone undetected.

Consistent intensity inhomogeneity correction in water-fat MRI.

To quantitatively and qualitatively evaluate the water-signal performance of the consistent intensity inhomogeneity correction (CIIC) method to correct for intensity inhomogeneities Water-fat volumes were acquired using 1.5 Tesla (T) and 3.0T symmetrically sampled 2-point Dixon three-dimensional MRI. Two datasets: (i) 10 muscle tissue regions of interest (ROIs) from 10 subjects acquired with both 1.5T and 3.0T whole-body MRI. (ii) Seven liver tissue ROIs from 36 patients imaged using 1.5T MRI at six time points after Gd-EOB-DTPA injection. The performance of CIIC was evaluated quantitatively by analyzing its impact on the dispersion and bias of the water image ROI intensities, and qualitatively using side-by-side image comparisons. CIIC significantly ( P1.5T≤2.3×10-4,P3.0T≤1.0×10-6) decreased the nonphysiological intensity variance while preserving the average intensity levels. The side-by-side comparisons showed improved intensity consistency ( Pint⁡≤10-6) while not introducing artifacts ( Part=0.024) nor changed appearances ( Papp≤10-6). CIIC improves the spatiotemporal intensity consistency in regions of a homogenous tissue type.

Abstract 1049: Quantitative immunofluorescence assessment of MET and epithelial to mesenchymal transition (EMT) biomarker modulation by antiangiogenic inhibitors in xenograft tumor tissues

Abstract We have previously reported the development of ELISA assays for intact MET, pY1235-MET, and pY1356-MET in tumor lysates (Srivastava et al, ASCO 2011). Here we report the development of a multiplex quantitative immunofluorescence assay (qIFA) for simultaneous detection of pY1235-MET and total MET in formalin-fixed paraffin-embedded (FFPE) tissues. We utilized a rabbit monoclonal antibody specific to pY1235-MET (with no detectable crossreactivity to pY1234-MET) to develop a highly specific and sensitive IFA assay with total MET (MET4 Mab; from G. Vande Woude, Van Andel Research Institute). Specificity of the IFA was demonstrated by HGF stimulation of A549 cells showing increased intensity of pY1235-MET which was completely inhibited by crizotinib but not by the non-MET specific multi-kinase inhibitor sorafenib, in vitro. The pY1235-MET epitope is stable in FFPE, and IFA detection was enhanced by EDTA (vs. Citrate) for antigen retrieval. Quantitative assessment of pY1235-MET was determined in xenograft models that demonstrate very high IFA expression of pY1235-MET and total MET via gene amplification (GTL-16 and SNU-5), lower expression in HGF-induced paracrine or autocrine cell lines (A549 and HT29), and no detectable staining for pY1235-MET in negative controls (SNU-1 and MDA-MB-231). We have demonstrated assay fitness for purpose using SNU-5 FFPE xenograft tumor samples from animals treated with increasing doses of crizotinib in vivo. Quantitative measurement by Definiens analysis of pY1235-MET and total MET in tissue regions of interest (ROI) showed 50% and 95% pY1235-MET inhibition with 12.5 mg/kg and 25 mg/kg crizotinib, respectively. There were no significant changes in total MET by IFA. A high correlation (R=0.899) was observed between % pY1235-MET/total MET ratio measured by IFA levels (expressed as the marker area/# nuclei for pY1235-MET and total MET per ROI) and % pY1235-MET/total MET ratio determined by ELISA levels (pM/ug protein). This quantitative MET IFA assay is currently being applied in conjunction with a previously developed EMT IFA assay (Navas et al, AACR 2013) for focal tissue analysis of pY1235-MET and total MET IFA expression as well as changes in epithelial to mesenchymal transition (EMT) in gastric tumor xenograft tissues treated with the VEGF inhibitor pazopanib, the MET inhibitor tivantinib (ARQ197), or the drug combination in vivo. These studies will determine whether pY1235-MET or total MET is induced by anti-VEGF inhibitors via increased EMT transition, and whether this effect can be reversed by combination with tivantinib. Funded by NCI Contract No. HHSN261200800001E Citation Format: Tony Navas, Scott L. Lawrence, Donna Butcher, Lindsay M. Dutko, Melinda G. Hollingshead, Robert J. Kinders, Ralph E. Parchment, Donald P. Bottaro, W. Marston Linehan, Joseph E. Tomaszewski, Apurva K. Srivastava, James H. Doroshow. Quantitative immunofluorescence assessment of MET and epithelial to mesenchymal transition (EMT) biomarker modulation by antiangiogenic inhibitors in xenograft tumor tissues. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1049. doi:10.1158/1538-7445.AM2014-1049

Real‐Time In Vivo Quantitative Monitoring of Drug Release by Dual‐Mode Magnetic Resonance and Upconverted Luminescence Imaging

Insufficient or excess drug doses, due to unknown actual drug concentrations at the focus, are one of the main causes of chemotherapy failure for cancers. In this regard, the real-time monitoring of the release of anticancer drugs from nanoparticle drug delivery systems is of crucial importance, but it remains a critical and unsolved challenge. Herein, we report the proposal and development of a novel concept of real-time monitoring of NIR-triggered drug release in vitro and in vivo by using simultaneous upconverted luminescence (UCL) and magnetic resonance (MR) imaging. Such a monitoring strategy features the high sensitivity of UCL and the high-resolution, noninvasiveness, and tissue-depth-independence of MR imaging. The dual-mode real-time and quantitative monitoring of drug release can be applied to determine online the drug concentrations in vivo in the tissue regions of interest and, therefore, to avoid insufficient or excess drug dosings.

Real‐Time In Vivo Quantitative Monitoring of Drug Release by Dual‐Mode Magnetic Resonance and Upconverted Luminescence Imaging

AbstractInsufficient or excess drug doses, due to unknown actual drug concentrations at the focus, are one of the main causes of chemotherapy failure for cancers. In this regard, the real‐time monitoring of the release of anticancer drugs from nanoparticle drug delivery systems is of crucial importance, but it remains a critical and unsolved challenge. Herein, we report the proposal and development of a novel concept of real‐time monitoring of NIR‐triggered drug release in vitro and in vivo by using simultaneous upconverted luminescence (UCL) and magnetic resonance (MR) imaging. Such a monitoring strategy features the high sensitivity of UCL and the high‐resolution, noninvasiveness, and tissue‐depth‐independence of MR imaging. The dual‐mode real‐time and quantitative monitoring of drug release can be applied to determine online the drug concentrations in vivo in the tissue regions of interest and, therefore, to avoid insufficient or excess drug dosings.

High-resolution diffusion-weighted imaging for the separation of benign from malignant BI-RADS 4/5 lesions found on breast MRI at 3T

To determine whether readout-segmented echo-planar diffusion imaging (RESOLVE) improves separation of malignant versus benign lesions compared to standard single-shot echo-planar imaging (ss-EPI) on BI-RADS 4/5 lesions detected on breast magnetic resonance imaging (MRI). Consecutive 3T breast MRI studies with BI-RADS 4/5 designation and subsequent biopsy or benign mastectomy were retrospectively identified. Freehand regions of interest (ROIs) were drawn on lesions and also on normal background fibroglandular tissue for comparison. Lesion-to-background contrast was evaluated by normalizing signal intensity of the lesion ROI by the normal background tissue ROI at b = 800. Statistical analysis used the Mann-Whitney/Wilcoxon rank-sum test for unpaired and Wilcoxon signed-rank for paired comparisons. Of 38 lesions in 32 patients, 10 were malignant. Lesion-to-background contrast was higher on RESOLVE than ss-EPI (1.80 ± 0.71 vs. 1.62 ± 0.63, P = 0.03). Mean apparent diffusion coefficient (ADC) was the same or lower on RESOLVE than ss-EPI, and this effect was largest in malignant lesions (RESOLVE 0.90 ± 0.13; ss-EPI 1.00 ± 0.13; median difference -0.10 (95% confidence interval [CI]: -0.17, -0.02) × 10(-3) mm(2) /sec; P = 0.014). By either diffusion method, there was a statistically significant difference between benign and malignant mean ADC (P < 0.001). Increased lesion-to-background contrast and improved separation of benign from malignant lesions by RESOLVE compared to standard diffusion suggests that RESOLVE may show promise as an adjunct to clinical breast MRI.

Abstract 1500: Development of a Quantitative Immunofluorescence imaging assay to assess β-catenin translocation and multiplex biomarkers for Epithelial-Mesenchymal Transition (EMT) in tumor tissues.

Abstract Background: Wnt/ß-catenin signaling and cadherin-mediated cell adhesion are two processes that promote cell proliferation and epithelial-mesenchymal transition (EMT) of carcinomas. Therapeutic inhibitors of Wnt-induced tumor activation prevent stabilization and nuclear translocation of β-catenin and putatively lead to inhibition of tumor metastasis by upregulation of E-Cadherin and downregulation of N-Cadherin and Vimentin. Methods: A multiplex quantitative immunofluorescence (qIFA) assay was developed to assess changes in levels of EMT biomarkers (E-Cadherin, N-Cadherin, Vimentin/Pancytokeratin) as well as monitor intracellular localization of β-catenin in tumor tissues. A panel of highly specific antibodies against EMT targets, directly-conjugated to various fluorophores, were optimized for multiplex staining of FFPE tissues using colorectal (CRC) and triple-negative breast (TNBC) cancer cell lines and xenograft tissues as tumor controls for target expression. Rat kidney was used as positive control for endogenous biomarker expression in tissues. Image acquisition was performed with Confocal and Epifluorescence microscopy. Image segmentation and quantitative multiplex analysis were performed using NIS Elements and Definiens Tissue Studio software to obtain total mean integrated signal per biomarker within a tissue region of interest. Results: Fitness for purpose evaluation of the biomarkers was performed in vitro with several cell lines and compounds to demonstrate nuclear translocation of β-catenin as well as EMT-mediated changes in E- to N-Cadherin ratio. A431 squamous epithelial cell lines treated with Lysophosphatidic acid (LPA) induced Adherens Junction (AJ) dissociation of membrane E-Cadherin and β-catenin while co-treatment with specific inhibitors to glycogen synthase kinase-3β (GSK-3β) induced a 5-fold increase in the nuclear to cytoplasmic mean intensity ratio of β-catenin after 24h. TGFβ-treatment of the NMuMG mouse epithelial cell line induced a significant decrease in E- to N-Cadherin membrane intensity ratio after 48 and 72h in vitro. Studies with human TNBC or APC-mutated CRC mouse xenograft models using HDAC or Src/Abl kinase inhibitors to compare pre- and post-treatment effects on EMT biomarker staining will be presented. Conclusion: We have developed a quantitative imaging assay that integrates multiplex changes in EMT biomarkers to assay pharmacodynamic activities of potential targeted agents currently in development at the National Cancer Institute (NCI). This assay could also be applied for retrospective analysis of clinical samples to document drug-induced changes in tumor phenotypes. Funded by NCI Contract No. HHSN261200800001E. Citation Format: Tony Navas, Robert J. Kinders, Karun Mutreja, Scott M. Lawrence, Donna Butcher, Melinda Hollingshead, Ralph E. Parchment, Joseph E. Tomaszewski, James H. Doroshow. Development of a Quantitative Immunofluorescence imaging assay to assess β-catenin translocation and multiplex biomarkers for Epithelial-Mesenchymal Transition (EMT) in tumor tissues. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1500. doi:10.1158/1538-7445.AM2013-1500

Effects of Subanesthetic Dose of Nitrous Oxide on Cerebral Blood Flow and Metabolism

Nitrous oxide, in a concentration of 50% or more, is a known cerebral vasodilator. This study investigated whether a lower dose (30%) of nitrous oxide would also increase cerebral blood flow. In addition, the authors wished to study whether the increase in cerebral blood flow was accompanied by an increase in cerebral metabolism. Multimodal Magnetic Resonance Imaging at 3T was performed, and data were obtained in 17 healthy volunteers during three inhalation conditions: medical air, oxygen-enriched medical air (40% oxygen), and 30% nitrous oxide with oxygen-enriched medical air (40% oxygen). Arterial spin labeling was used to derive the primary tissue specific hemodynamic outcomes: cerebral blood flow, arterial blood volume and arterial transit times. Magnetic Resonance Susceptometry and proton Magnetic Resonance Spectroscopy were used for secondary metabolic outcomes: venous oxygenation, oxygen extraction fraction, cerebral metabolic oxygen rate and prefrontal metabolites. Nitrous oxide in 40% oxygen, but not 40% oxygen alone, significantly increased gray matter cerebral blood flow (22%; P < 0.05) and arterial blood volume (41%; P < 0.05). Venous oxygenation increased in both oxygen and nitrous oxide conditions. Compared with medical air inhalation, nitrous oxide condition caused a significantly larger decrease in oxygen extraction fraction than 40% oxygen alone (mean [SD] 11.3 [5.6]% vs. 8.3 [5.9]% P < 0.05), while global cerebral metabolic rate and prefrontal metabolites remained unchanged. This study demonstrates that 30% nitrous oxide in oxygen-enriched air (40% oxygen) significantly increases cerebral perfusion, and reduces oxygen extraction fraction, reflecting a strong arterial vasodilatory effect without associated increases in metabolism.

Novel mass spectrometry imaging software assisting labeled normalization and quantitation of drugs and neuropeptides directly in tissue sections

MALDI MS imaging has been extensively used to produce qualitative distribution maps of proteins, peptides, lipids, small molecule pharmaceuticals and their metabolites directly in biological tissue sections. There is growing demand to quantify the amount of target compounds in the tissue sections of different organs. We present a novel MS imaging software including protocol for the quantitation of drugs, and for the first time, an endogenous neuropeptide directly in tissue sections. After selecting regions of interest on the tissue section, data is read and processed by the software using several available methods for baseline corrections, subtractions, denoising, smoothing, recalibration and normalization. The concentrations of in vivo administered drugs or endogenous compounds are then determined semi-automatically using either external standard curves, or by using labeled compounds, i.e., isotope labeled analogs as standards. As model systems, we have quantified the distribution of imipramine and tiotropium in the brain and lung of dosed rats. Substance P was quantified in different mouse brain structures, which correlated well with previously reported peptide levels. Our approach facilitates quantitative data processing and labeled standards provide better reproducibility and may be considered as an efficient tool to quantify drugs and endogenous compounds in tissue regions of interest.

Parametric Subharmonic Imaging Using a Commercial Intravascular Ultrasound Scanner

The feasibility of visualizing atherosclerotic plaque using parametric subharmonic intravascular ultrasound (IVUS) was investigated in vivo. Atherosclerosis was induced in the aorta of 2 rabbits. Following injection of Definity (Lantheus Medical Imaging, North Billerica, MA), radiofrequency IVUS signals were acquired at 40 MHz with a Galaxy IVUS scanner (Boston Scientific/Scimed, Natick, MA). Subharmonic imaging (SHI; receiving at 20 MHz) was performed offline by applying an 8-order equalization filter. Contrast-to-tissue ratios (CTRs) were computed for the vessel relative to the plaque area over 4 time points. Contrast-to-tissue ratios were also calculated for the plaque-tissue and vessel-tissue from 4 tissue regions of interest at 4 time points. Finally, parametric images showing the cumulative maximum intensity (CMI), time to peak, perfusion (PER), and time-integrated intensity (TII) were generated for the fundamental and subharmonic data sets, and CTR measurements were repeated. Injection of the contrast agent resulted in improved delineation between plaque and the vessel lumen. Subharmonic imaging resulted in noticeable tissue suppression, although the intensity from the contrast agent was reduced. No significant improvement in the plaque to vessel lumen CTR was observed between the subharmonic and fundamental IVUS (2.1 ± 3.64 versus 2.2 ± 4.20; P = .5). However, the CTR for plaque-tissue was improved (11.8 ± 7.32 versus 9.9 ± 7.06; P < .0001) for SHI relative to fundamental imaging. Cumulative-maximum-intensity and TII maps of both fundamental and subharmonic data provided increased CTRs relative to nonparametric data sets (P < .002). Additionally, the CMI, PER, and TII of SHI IVUS showed significantly improved vessel-plaque CTRs for SHI relative to the fundamental (P < .04). Parametric SHI IVUS of atherosclerotic plaque is feasible and improves the visualization of the plaque.

Assessment of Skin Microvascular Function and Dysfunction With Laser Speckle Contrast Imaging

In recent years, skin microcirculation has been considered an easily accessible and potentially representative vascular bed to evaluate and understand the mechanisms of microvascular function and dysfunction.1–3 Vascular dysfunction (including impaired endothelium-dependent vasodilation) induced by different pathologies is evident in the cutaneous circulation.4–7 It has been suggested that the skin microcirculation may mirror generalized systemic vascular dysfunction in magnitude and underlying mechanisms.1 Furthermore, minimally invasive skin-specific methodologies using laser systems make the cutaneous circulation a useful translational model for investigating mechanisms of skin physiology and skin pathophysiology induced either by skin disease itself or by other diseases such as vascular, rheumatologic, and pneumologic. To date, the skin has been used as a circulation model to investigate vascular mechanisms in a variety of diseased states, including hypercholesterolemia,8 Alzheimer disease,9 carpal tunnel syndrome,10 schizophrenia,11 hypertension,6 renal disease,12 type 2 diabetes,13 peripheral vascular disease,14 atherosclerotic coronary artery disease,2 heart failure,15 systemic sclerosis,16 obesity,17 primary aging,18,19 and sleep apnea.20 Assessment of skin microvascular function can be done by both invasive and noninvasive techniques. Among noninvasive techniques, laser systems are mainly used.21 The recent development of the laser speckle contrast imaging (LSCI) technique for monitoring skin microvascular function enables its use as a surrogate end point in clinical trials. LSCI allows for noncontact, real-time, and noninvasive monitoring of cutaneous blood flow changes.22,23 Recent evidence has shown that the LSCI technique dramatically reduces the variability of clinical measurements compared with laser Doppler flowmetry (LDF), making the technique a fascinating tool to facilitate microvascular studies in clinical routine.23,24 In this review, we describe …

Experimental validation of acoustic radiation force induced shear wave interference patterns

A novel elasticity imaging system founded on the use of acoustic radiation forces from a dual beam arrangement to generate shear wave interference patterns is described. Acquired pulse-echo data and correlation-based techniques were used to estimate the resultant deformation and to visualize tissue viscoelastic response. The use of normal versus axicon focal configurations was investigated for effects on shear wave generation. Theoretical models were introduced and shown in simulation to accurately predict shear wave propagation and interference pattern properties. In a tissue-mimicking phantom, experimental results are in congruence with theoretical predictions. Using dynamic acoustic radiation force excitation, results confirm that shear wave interference patterns can be produced remotely in a particular tissue region of interest (ROI). Overall, preliminary results are encouraging and the system described may prove feasible for interrogating the viscoelastic properties of normal and diseased tissue types.

Data-driven classification of ventilated lung tissues using electrical impedance tomography

Current methods for identifying ventilated lung regions utilizing electrical impedance tomography images rely on dividing the image into arbitrary regions of interest (ROI), manually delineating ROI, or forming ROI with pixels whose signal properties surpass an arbitrary threshold. In this paper, we propose a novel application of a data-driven classification method to identify ventilated lung ROI based on forming k clusters from pixels with correlated signals. A standard first-order model for lung mechanics is then applied to determine which ROI correspond to ventilated lung tissue. We applied the method in an experimental study of 16 mechanically ventilated swine in the supine position, which underwent changes in positive end-expiratory pressure (PEEP) and fraction of inspired oxygen (FIO2). In each stage of the experimental protocol, the method performed best with k = 4 and consistently identified 3 lung tissue ROI and 1 boundary tissue ROI in 15 of the 16 subjects. When testing for changes from baseline in lung position, tidal volume, and respiratory system compliance, we found that PEEP displaced the ventilated lung region dorsally by 2 cm, decreased tidal volume by 1.3%, and increased the respiratory system compliance time constant by 0.3 s. FIO2 decreased tidal volume by 0.7%. All effects were tested at p < 0.05 with n = 16. These findings suggest that the proposed ROI detection method is robust and sensitive to ventilation dynamics in the experimental setting.

Detection and Quantification of Large-Vessel Inflammation with 11C-(R)-PK11195 PET/CT

We investigated whether PET/CT angiography using 11C-(R)-PK11195, a selective ligand for the translocator protein (18 kDa) expressed in activated macrophages, could allow imaging and quantification of arterial wall inflammation in patients with large-vessel vasculitis. Seven patients with systemic inflammatory disorders (3 symptomatic patients with clinical suspicion of active vasculitis and 4 asymptomatic patients) underwent PET with 11C-(R)-PK11195 and CT angiography to colocalize arterial wall uptake of 11C-(R)-PK11195. Tissue regions of interest were defined in bone marrow, lung parenchyma, wall of the ascending aorta, aortic arch, and descending aorta. Blood-derived and image-derived input functions (IFs) were generated. A reversible 1-tissue compartment with 2 kinetic rate constants and a fractional blood volume term were used to fit the time-activity curves to calculate total volume of distribution (VT). The correlation between VT and standardized uptake values was assessed. VT was significantly higher in symptomatic than in asymptomatic patients using both image-derived total plasma IF (0.55±0.15 vs. 0.27±0.12, P=0.009) and image-derived parent plasma IF (1.40±0.50 vs. 0.58±0.25, P=0.018). A good correlation was observed between VT and standardized uptake value (R=0.79; P=0.03). 11C-(R)-PK11195 imaging allows visualization of macrophage infiltration in inflamed arterial walls. Tracer uptake can be quantified with image-derived IF without the need for metabolite corrections and evaluated semiquantitatively with standardized uptake values.

A comparison of endometrial and subendometrial vascularity assessed by three-dimensional ultrasonography and power Doppler angiography between healthy fertile women and women with unexplained primary recurrent miscarriage

We compared the characteristics of endometrial-subendometrial vascularity 7 days after ovulation of a natural cycle by transvaginal three-dimensional ultrasonography and power Doppler angiography between 88 patients with unexplained recurrent miscarriage and 46 healthy fertile women. Endometrial vascularization index, flow index, and vascularization flow index, as well as subendometrial vascularization index and vascularization flow index, were reduced significantly in the group with unexplained recurrent miscarriage.

Added soft tissue contrast using signal attenuation and the fractal dimension for optical coherence tomography images of porcine arterial tissue

Optical coherence tomography (OCT) images of left-descending coronary tissues harvested from three porcine specimens were acquired with a home-build swept-source OCT setup. Despite the fact that OCT is capable of acquiring high resolution circumferential images of vessels, many distinct histological features of a vessel have comparable optical properties leading to poor contrast in OCT images. Two classification methods were tested in this report for the purpose of enhancing contrast between soft-tissue components of porcine coronary vessels. One method involved analyzing the attenuation of the OCT signal as a function of light penetration into the tissue. We demonstrated that by analyzing the signal attenuation in this manner we were able to differentiate two media sub-layers with different orientations of the smooth muscle cells. The other classification method used in our study was fractal analysis. Fractal analysis was implemented in a box-counting (fractal dimension) image-processing code and was used as a tool to differentiate and quantify variations in tissue texture at various locations in the OCT images. The calculated average fractal dimensions had different values in distinct regions of interest (ROI) within the imaged coronary samples. When compared to the results obtained by using the attenuation of the OCT signal, the method of fractal analysis demonstrated better classification potential for distinguishing amongst the tissue ROI.

A Spectral Analysis Approach for Determination of Regional Rates of Cerebral Protein Synthesis with the L-[1-11C]leucine PET Method

A spectral analysis approach was used to estimate kinetic model parameters of the L-[1-(11)C]leucine positron emission tomography (PET) method and regional rates of cerebral protein synthesis (rCPS) in predefined regions of interest (ROIs). Unlike analyses based on the assumption that tissue ROIs are kinetically homogeneous, spectral analysis allows for heterogeneity within a region. To improve estimation performance, a new approach was developed-spectral analysis with iterative filter (SAIF). In simulation SAIF produced low bias, low variance estimates of the influx rate constant for leucine (K(1)), blood volume fraction (V(b)), fraction of unlabeled leucine in the tissue precursor pool for protein synthesis derived from arterial plasma (lambda), and rCPS. Simulation of normal count rate studies showed that SAIF applied to ROI time-activity curves (TACs) performed comparably to the basis function method (BFM) applied to voxel TACs when voxelwise estimates were averaged over all voxels in the ROI. At low count rates, however, SAIF performed better. In measured L-[1-(11)C]leucine PET data, there was good agreement between ROI-based SAIF estimates and average voxelwise BFM estimates of K(1), V(b), lambda, and rCPS. We conclude that SAIF sufficiently addresses the problem of tissue heterogeneity in ROI data and provides a valid tool for estimation of rCPS, even in low count rate studies.

Accuracy of real time noninvasive temperature measurements using magnetic resonance thermal imaging in patients treated for high grade extremity soft tissue sarcomas

To establish accuracy of real time noninvasive temperature measurements using magnetic resonance thermal imaging in patients treated for high grade extremity soft tissue sarcomas. Protocol patients with advanced extremity sarcomas were treated with external beam radiation therapy and hyperthermia. Invasive temperature measures were compared to noninvasive magnetic resonance thermal imaging (MRTI) at 1.5 T performed during hyperthermia. Volumetric temperature rise images were obtained using the proton resonance frequency shift (PRFS) technique during heating in a 140 MHz miniannular phased array applicator. MRTI temperature changes were compared to invasive measurements of temperature with a multisensor fiber optic probe inside a #15 g catheter in the tumor. Since the PRFS technique is sensitive to drifts in the primary imaging magnetic field, temperature change distributions were corrected automatically during treatment using temperature-stable reference materials to characterize field changes in 3D. The authors analyzed MRT images and compared, in evaluable treatments, MR-derived temperatures to invasive temperatures measured in extremity sarcomas. Small regions of interest (ROIs) were specified near each invasive sensor identified on MR images. Temperature changes in the interstitial sensors were compared to the corresponding ROI PRFS-based temperature changes over the entire treatment and over the steady-state period. Nonevaluable treatments (motion/imaging artifacts, noncorrectable drifts) were not included in the analysis. The mean difference between MRTI and interstitial probe measurements was 0.91 degrees C for the entire heating time and 0.85 degrees C for the time at steady state. These values were obtained from both tumor and normal tissue ROIs. When the analysis is done on just the tumor ROIs, the mean difference for the whole power on time was 0.74 degrees C and during the period of steady state was 0.62 degrees C. The data show that for evaluable treatments, excellent correlation (deltaT < 1 degrees C) of MRTI-ROI and invasive measurements can be achieved, but that motion and other artifacts are still serious challenges that must be overcome in future work.