Faculty Bibliography
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314
Characterization of malignancy of adnexal lesions using ADC entropy: Comparison with mean ADC and qualitative DWI assessment
PURPOSE: To establish the utility of apparent diffusion coefficient (ADC) entropy in discrimination of benign and malignant adnexal lesions, using histopathology as the reference standard, via comparison of the diagnostic performance of ADC entropy with mean ADC and with visual assessments of adnexal lesions on conventional and diffusion-weighted sequences. MATERIALS AND METHODS: In all, 37 adult female patients with an ovarian mass that was resected between June 2006 and January 2011 were included. Volume-of-interest was drawn to incorporate all lesion voxels on every slice that included the mass on the ADC map, from which whole-lesion mean ADC and ADC entropy were calculated. Two independent radiologists also rated each lesion as benign or malignant based on visual assessment of all sequences. The Mann-Whitney test and logistic regression for correlated data were used to compare performance of mean ADC, ADC entropy, and the visual assessments. RESULTS: No statistically significant difference was observed in mean ADC between benign and malignant adnexal lesions (P = 0.768). ADC entropy was significantly higher in malignant than in benign lesions (P = 0.009). Accuracy was significantly greater for ADC entropy than for mean ADC (0.018). ADC entropy and visual assessment by the less-experienced reader showed similar accuracy (P >/= 0.204). The more experienced reader's accuracy was significantly greater than that of all other assessments (P
PMID: 23188749
ISSN: 1053-1807
CID: 203912
Proceedings of SPIE (The International Society for Optical Engineering). 2013:8669:866925-866925.DOI: 10.1117/12.2007154
Clustering of lung adenocarcinomas classes using automated texture analysis on CT images
Purpose: To assess whether automated texture analysis of CT images enables discrimination among pathologic classes of lung adenocarcinomas, and thus serves as an in vivo biomarker of lung cancer prognosis. Materials and Methods: Chest CTs of 30 nodules in 30 patients with resected adenocarcinomas were evaluated by a pulmonary pathologist who classified each resected cancer according to the International Association for the Study of Lung Cancer (IASLC) system. The categories included adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), lepidic-predominant adenocarcinoma (LPA), and other invasive adenocarcinomas (INV). 3D volumes of interest (VOIs) and 2D regions of interest (ROIs) were then constructed for each nodule. A comprehensive set of N=279 texture parameters were computed for both 3D and 2D regions. Clustering and classification of these parameters were performed with linear discriminant analysis (LDA) using features determined by optimal subsets. Results: Of the 30 adenocarcinomas, there were 13 INV, 11 LPA, 3 MIA, and 3 AIS. AIS and MIA groups were analyzed together. With all 3 classes, LDA classified 17 of 30 nodules correctly using the nearest neighbor (k=1) method. When only the two largest classes (INV and LPA) were used, 21 of 24 nodules were classified correctly. With 3 classes and 2D texture analysis, and when using only the two largest groups, LDA was able to correctly classify all nodules. Conclusion: CT texture parameters determined by optimal subsets allows for effective clustering of adenocarcinoma classes. These results suggest the potential use of automated (or computer-assisted) CT image analysis to predict the invasive pathologic character of lung nodules. Our approach overcomes the limitations of current radiologic interpretation, such as subjectivity, interand intra-observer variability, and the effect of reader experience
INSPEC:13750846
ISSN: 0277-786x
CID: 563752
Cerebrovascular reactivity to carbon dioxide in Alzheimer's disease
There is growing evidence that cerebrovascular reactivity to carbon dioxide (CVRCO2) is impaired in Alzheimer's disease (AD). Preclinical and animal studies suggest chronic hypercontractility in brain vessels in AD. We review (a) preclinical studies of mechanisms for impaired CVRCO2 in AD; (b) clinical studies of cerebrovascular function in subjects with AD dementia, mild cognitive impairment (MCI), and normal cognition. Although results of clinical studies are inconclusive, an increasing number of reports reveal an impairment of vascular reactivity to carbon dioxide in subjects with AD, and possibly also in MCI. Thus, CVRCO2 may be an attractive means to detect an early vascular dysfunction in subjects at risk.
PMCID:3776495
PMID: 23478306
ISSN: 1387-2877
CID: 335512
Diffusion-Weighted Intravoxel Incoherent Motion Imaging of Renal Tumors With Histopathologic Correlation
PURPOSE: The aim of this study was to use intravoxel incoherent motion diffusion-weighted imaging to discriminate subtypes of renal neoplasms and to assess agreement between intravoxel incoherent motion (perfusion fraction, fp) and dynamic contrast-enhanced magnetic resonance imaging (MRI) metrics of tumor vascularity. SUBJECTS AND METHODS: In this Health Insurance Portability and Accountability Act-compliant, institutional review board-approved prospective study, 26 patients were imaged at 1.5-T MRI using dynamic contrast-enhanced MRI with high temporal resolution and diffusion-weighted imaging using 8 b values (range, 0-800 s/mm). Perfusion fraction (fp), tissue diffusivity (Dt), and pseudodiffusivity (Dp) were calculated using biexponential fitting of the diffusion data. Apparent diffusion coefficient (ADC) was calculated with monoexponential fit using 3 b values of 0, 400, and 800 s/mm. Dynamic contrast-enhanced data were processed with a semiquantitative method to generate model-free parameter cumulative initial area under the curve of gadolinium concentration at 60 seconds (CIAUC60). Perfusion fraction, Dt, Dp, ADC, and CIAUC60 were compared between different subtypes of renal lesions. Perfusion fraction was correlated with CIAUC60. RESULTS: We examined 14 clear cell, 4 papillary, 5 chromophobe, and 3 cystic renal cell carcinomas (RCCs). Although fp had higher accuracy (area under the curve, 0.74) for a diagnosis of clear cell RCC compared with Dt or ADC, the combination of fp and Dt had the highest accuracy (area under the curve, 0.78). The combination of fp and Dt diagnosed papillary RCC and cystic RCC with 100% accuracy, and clear cell RCC and chromophobe RCC, with 86.5% accuracy. There was significant strong correlation between fp and CIAUC60 (r = 0.82; P < 0.001). CONCLUSION: Intravoxel incoherent motion parameters fp and Dt can discriminate renal tumor subtypes. Perfusion fraction demonstrates good correlation with CIAUC60 and can assess degree of tumor vascularity without the use of exogenous contrast agent.
PMID: 22996315
ISSN: 0020-9996
CID: 179984
A new method to analyze dGEMRIC measurements in femoroacetabular impingement: preliminary validation against arthroscopic findings
OBJECTIVE: To validate a new method to analyze delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) measurements in the hip for early assessment of cartilage defects in femoroacetabular impingement (FAI). METHODS: We performed a retrospective review of 10 hips in 10 FAI patients, who underwent hip arthroscopy. T(1)-weighted images and dGEMRIC T(1) maps were acquired at 1.5 T on coronal planes, including the anterior-superior, superior, posterior-superior hip cartilage. For all slices, a region of interest (ROI) was defined over the central portion of the femoral cartilage, assumed to be healthy, and T(1) values (x) were transformed to standard scores (z) using z = (x -mu)/sigma, where mu and sigma are the average and standard deviation of T(1) in the femoral ROI. Diagnostic performance of the resulting standardized dGEMRIC maps was evaluated against intraoperative findings and compared with that of a previously proposed dGEMRIC analysis as well as morphologic assessment. RESULTS: Assuming z = -2 or z = -3 as the threshold between normal and degenerated cartilage, sensitivity, specificity and accuracy were 88%, 51% and 62%, and 71%, 63% and 65%, respectively. By using T(1) = 500 ms as single threshold for all dGEMRIC T(1) maps, these values became 47%, 58% and 55%, whereas they were 47%, 79% and 70% for morphologic evaluation. CONCLUSIONS: Standardized dGEMRIC can increase the sensitivity in detecting abnormal cartilage in FAI and has the potential to improve the clinical interpretation of dGEMRIC measurements in FAI, by removing the effect of inter- and intra-patient T(1) variability.
PMID: 22771774
ISSN: 1063-4584
CID: 177023
Intravoxel Incoherent Motion and Diffusion-Tensor Imaging in Renal Tissue under Hydration and Furosemide Flow Challenges
Purpose:To assess the reproducibility and the distribution of intravoxel incoherent motion (IVIM) and diffusion-tensor (DT) imaging parameters in healthy renal cortex and medulla at baseline and after hydration or furosemide challenges.Materials and Methods:Using an institutional review board-approved HIPAA-compliant protocol with written informed consent, IVIM and DT imaging were performed at 3 T in 10 volunteers before and after water loading or furosemide administration. IVIM (apparent diffusion coefficient [ADC], tissue diffusivity [D(t)], perfusion fraction [f(p)], pseudodiffusivity [D(p)]) and DT (mean diffusivity [MD], fractional anisotropy [FA], eigenvalues [lambda(i)]) imaging parameters and urine output from serial bladder volumes were calculated. (a) Reproducibility was quantified with coefficient of variation, intraclass correlation coefficient, and Bland-Altman limits of agreement; (b) contrast and challenge response were quantified with analysis of variance; and (c) Pearson correlations were quantified with urine output.Results:Good reproducibility was found for ADC, D(t), MD, FA, and lambda(i) (average coefficient of variation, 3.7% [cortex] and 5.0% [medulla]), and moderate reproducibility was found for D(p), f(p), and f(p) . D(p) (average coefficient of variation, 18.7% [cortex] and 25.9% [medulla]). Baseline cortical diffusivities significantly exceeded medullary values except D(p), for which medullary values significantly exceeded cortical values, and lambda(1,) which showed no contrast. ADC, D(t), MD, and lambda(i) increased significantly for both challenges. Medullary diffusivity increases were dominated by transverse diffusion (1.72 +/- 0.09 [baseline] to 1.79 +/- 0.10 [hydration] mum(2)/msec, P = .0059; or 1.86 +/- 0.07 [furosemide] mum(2)/msec, P = .0094). Urine output correlated with cortical ADC with furosemide (r = 0.7, P = .034) and with medullary lambda(1) (r = 0.83, P = .0418), lambda(2) (r = 0.85, P = .0301), and MD (r = 0.82, P = .045) with hydration.Conclusion:Diffusion MR metrics are sensitive to flow changes in kidney induced by diuretic challenges. The results of this study suggest that vascular flow, tubular dilation, water reabsorption, and intratubular flow all play important roles in diffusion-weighted imaging contrast.(c) RSNA, 2012.
PMID: 22523327
ISSN: 0033-8419
CID: 167147
Proceedings of the National Academy of Sciences of the United States of America (PNAS). 2012:109(10):3985-90.DOI: 10.1073/pnas.1105829109
Association of common genetic variants in GPCPD1 with scaling of visual cortical surface area in humans
Visual cortical surface area varies two- to threefold between human individuals, is highly heritable, and has been correlated with visual acuity and visual perception. However, it is still largely unknown what specific genetic and environmental factors contribute to normal variation in the area of visual cortex. To identify SNPs associated with the proportional surface area of visual cortex, we performed a genome-wide association study followed by replication in two independent cohorts. We identified one SNP (rs6116869) that replicated in both cohorts and had genome-wide significant association (P(combined) = 3.2 x 10(-8)). Furthermore, a metaanalysis of imputed SNPs in this genomic region identified a more significantly associated SNP (rs238295; P = 6.5 x 10(-9)) that was in strong linkage disequilibrium with rs6116869. These SNPs are located within 4 kb of the 5' UTR of GPCPD1, glycerophosphocholine phosphodiesterase GDE1 homolog (Saccharomyces cerevisiae), which in humans, is more highly expressed in occipital cortex compared with the remainder of cortex than 99.9% of genes genome-wide. Based on these findings, we conclude that this common genetic variation contributes to the proportional area of human visual cortex. We suggest that identifying genes that contribute to normal cortical architecture provides a first step to understanding genetic mechanisms that underlie visual perception.
PMCID:3309762
PMID: 22343285
ISSN: 0027-8424
CID: 179987
Characterizing brain oxygen metabolism in patients with multiple sclerosis with T2-relaxation-under-spin-tagging MRI
In this study, venous oxygen saturation and oxygen metabolic changes in multiple sclerosis (MS) patients were assessed using a recently developed T2-relaxation-under-spin-tagging (TRUST) magnetic resonance imaging (MRI), which measures the superior sagittal venous sinus blood oxygenation (Yv) and cerebral metabolic rate of oxygen (CMRO(2)), an index of global oxygen consumption. Thirty patients with relapsing-remitting MS and 30 age-matched healthy controls were studied using TRUST at 3 T MR. The mean expanded disability status scale (EDSS) of the patients was 2.3 (range, 0 to 5.5). We found significantly increased Yv (P<0.0001) and decreased CMRO(2) (P=0.003) in MS patients (mean+/-s.d.: 65.9%+/-5.1% and 138.8+/-35.4 mumol per 100 g per minute) as compared with healthy control subjects (60.2%+/-4.0% and 180.2+/-24.8 mumol per 100 g per minute, respectively), implying decrease of oxygen consumption in MS. There was a significant positive correlation between Yv and EDSS and between Yv and lesion load in MS patients (n=30); on the contrary, there was a significant negative correlation between CMRO(2) and EDSS and between CMRO(2) and lesion load (n=12). There was no correlation between Yv and brain atrophy measures. This study showed preliminary evidence of the potential utility of TRUST in global oxygen metabolism. Our results of significant underutilization of oxygen in MS raise important questions regarding mitochondrial respiratory dysfunction and neurodegeneration of the disease.
PMCID:3293125
PMID: 22252237
ISSN: 0271-678x
CID: 158690
Proceedings of SPIE (The International Society for Optical Engineering). 2012:8316.DOI: 10.1117/12.911369
Imaging of prostate cancer: a platform for 3D co-registration of in-vivo MRI ex-vivo MRI and pathology
OBJECTIVES: Multi-parametric MRI is emerging as a promising method for prostate cancer diagnosis. prognosis and treatment planning. However, the localization of in-vivo detected lesions and pathologic sites of cancer remains a significant challenge. To overcome this limitation we have developed and tested a system for co-registration of in-vivo MRI, ex-vivo MRI and histology. MATERIALS AND METHODS: Three men diagnosed with localized prostate cancer (ages 54-72, PSA levels 5.1-7.7 ng/ml) were prospectively enrolled in this study. All patients underwent 3T multi-parametric MRI that included T2W, DCE-MRI, and DWI prior to robotic-assisted prostatectomy. Ex-vivo multi-parametric MRI was performed on fresh prostate specimen. Excised prostates were then sliced at regular intervals and photographed both before and after fixation. Slices were perpendicular to the main axis of the posterior capsule, i.e., along the direction of the rectal wall. Guided by the location of the urethra, 2D digital images were assembled into 3D models. Cancer foci, extra-capsular extensions and zonal margins were delineated by the pathologist and included in 3D histology data. A locally-developed software was applied to register in-vivo, ex-vivo and histology using an over-determined set of anatomical landmarks placed in anterior fibro-muscular stroma, central. transition and peripheral zones. The mean root square distance across corresponding control points was used to assess co-registration error. RESULTS: Two specimens were pT3a and one pT2b (negative margin) at pathology. The software successfully fused in-vivo MRI. ex-vivo MRI fresh specimen and histology using appropriate (rigid and affine) transformation models with mean square error of 1.59 mm. Coregistration accuracy was confirmed by multi-modality viewing using operator-guided variable transparency. CONCLUSION: The method enables successful co-registration of pre-operative MRI, ex-vivo MRI and pathology and it provides initial evidence of feasibility of MRI-guided surgical planning.
PMCID:3928603
PMID: 24563727
ISSN: 1996-756x
CID: 918082
The ADNI Publication Policy: Commensurate recognition of critical contributors who are not authors
An efficient approach to certain types of biomedical research requires a scale that precludes involvement of all critical contributors in all aspects of experimental design, execution, and as well as writing of most, if not all, derived works. Guarantors of both the integrity of the data and of its subsequent analyses are required. When separate groups are responsible for each of these activities, each should be readily identifiable both in the primary publication and in all subsequent citations. We describe the publication policy of the Alzheimer Disease Neuroimaging Initiative (ADNI), its origins and its acceptance by the editorial and scientific communities.
PMCID:3676932
PMID: 22100665
ISSN: 1053-8119
CID: 158646
