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Immunotherapy is used to treat almost all patients with advanced non-small cell lung cancer (NSCLC); however, identifying robust predictive biomarkers remains challenging. Here we show the predictive capacity of integrating medical imaging, histopathologic and genomic features to predict immunotherapy response using a cohort of 247 patients with advanced NSCLC with multimodal baseline data obtained during diagnostic clinical workup, including computed tomography scan images, digitized programmed death ligand-1 immunohistochemistry slides and known outcomes to immunotherapy. Using domain expert annotations, we developed a computational workflow to extract patient-level features and used a machine-learning approach to integrate multimodal features into a risk prediction model. Our multimodal model (area under the curve (AUC) = 0.80, 95% confidence interval (CI) 0.74–0.86) outperformed unimodal measures, including tumor mutational burden (AUC = 0.61, 95% CI 0.52–0.70) and programmed death ligand-1 immunohistochemistry score (AUC = 0.73, 95% CI 0.65–0.81). Our study therefore provides a quantitative rationale for using multimodal features to improve prediction of immunotherapy response in patients with NSCLC using expert-guided machine learning.

Human cancers arise from environmental, heritable and somatic factors, but how these mechanisms interact in tumorigenesis is poorly understood. Studying 17,152 prospectively sequenced patients with cancer, we identified pathogenic germline variants in cancer predisposition genes, and assessed their zygosity and co-occurring somatic alterations in the concomitant tumors. Two major routes to tumorigenesis were apparent. In carriers of pathogenic germline variants in high-penetrance genes (5.1% overall), lineage-dependent patterns of biallelic inactivation led to tumors exhibiting mechanism-specific somatic phenotypes and fewer additional somatic oncogenic drivers. Nevertheless, 27% of cancers in these patients, and most tumors in patients with pathogenic germline variants in lower-penetrance genes, lacked particular hallmarks of tumorigenesis associated with the germline allele. The dependence of tumors on pathogenic germline variants is variable and often dictated by both penetrance and lineage, a finding with implications for clinical management. A study of 17,152 patients with cancer identified pathogenic germline variants in cancer predisposition genes. Although tumors showed biallelic inactivation for high-penetrance genes, this was not the case in most patients with pathogenic variants in low-penetrance genes, suggesting alternative routes to tumorigenesis.

BACKGROUND: Patterns of metastasis in cancer are increasingly relevant to prognostication and treatment planning but have historically been documented by means of autopsy series. PURPOSE: To show the feasibility of using natural language processing (NLP) to gather accurate data from radiology reports for assessing spatial and temporal patterns of metastatic spread in a large patient cohort. MATERIALS AND METHODS: In this retrospective longitudinal study, consecutive patients who underwent CT from July 2009 to April 2019 and whose CT reports followed a departmental structured template were included. Three radiologists manually curated a sample of 2219 reports for the presence or absence of metastases across 13 organs; these manually curated reports were used to develop three NLP models with an 80%-20% split for training and test sets. A separate random sample of 448 manually curated reports was used for validation. Model performance was measured by accuracy, precision, and recall for each organ. The best-performing NLP model was used to generate a final database of metastatic disease across all patients. For each cancer type, statistical descriptive reports were provided by analyzing the frequencies of metastatic disease at the report and patient levels. RESULTS: In 91 665 patients (mean age ± standard deviation, 61 years ± 15; 46 939 women), 387 359 reports were labeled. The best-performing NLP model achieved accuracies from 90% to 99% across all organs. Metastases were most frequently reported in abdominopelvic (23.6% of all reports) and thoracic (17.6%) nodes, followed by lungs (14.7%), liver (13.7%), and bones (9.9%). Metastatic disease tropism is distinct among common cancers, with the most common first site being bones in prostate and breast cancers and liver among pancreatic and colorectal cancers. CONCLUSION: Natural language processing may be applied to cancer patients’ CT reports to generate a large database of metastatic phenotypes. Such a database could be combined with genomic studies and used to explore prognostic imaging phenotypes with relevance to treatment planning. © RSNA, 2021 Online supplemental material is available for this article.

Mucinous carcinomas can arise in any organ with epithelial cells that produce mucus. While mucinous tumors from different organs are histologically similar, it remains to be elucidated whether they share molecular alterations. Here we analyzed a total of 902 patients across six cancer types by comparing mucinous and non-mucinous samples, integrating text mining of pathology reports, gene expression, methylation, mutational and copy-number profiling. We found that, in addition to genes involved in mucin processing and secretion, MUC2 up-regulation is a multi-cancer biomarker of mucinous histology and is regulated by DNA methylation in colorectal, breast and stomach cancer. The majority of carcinomas with mucinous differentiation had fewer DNA copy-number alterations than non-mucinous tumors. The tumor mutational burden was lower in breast and lung with mucinous differentiation compared to their non-mucinous counterparts. We found several differences in the frequency of oncogenic gene and pathway alterations between mucinous and non-mucinous carcinomas, including a lower frequency of p53 pathway alterations in colorectal and lung cancer, and a lower frequency of PI-3-Kinase/Akt pathway alterations in breast and stomach cancer with mucinous differentiation. This study shows that carcinomas with mucinous differentiation originating from different organs share transcriptomic and genomic similarities. These results might pave the way for a more biologically relevant taxonomy for these rare cancers., info:eu-repo/semantics/published

Stably acquired mutations in hematopoietic cells represent substrates of selection that may lead to clonal hematopoiesis (CH), a common state in cancer patients that is associated with a heightened risk of leukemia development. Owing to technical and sample size limitations, most CH studies have characterized gene mutations or mosaic chromosomal alterations (mCAs) individually. Here we leverage peripheral blood sequencing data from 32,442 cancer patients to jointly characterize gene mutations (n = 14,789) and mCAs (n = 383) in CH. Recurrent composite genotypes resembling known genetic interactions in leukemia genomes underlie 23% of all detected autosomal alterations, indicating that these selection mechanisms are operative early in clonal evolution. CH with composite genotypes defines a patient group at high risk of leukemia progression (3-year cumulative incidence 14.6%, CI: 7–22%). Multivariable analysis identifies mCA as an independent risk factor for leukemia development (HR = 14, 95% CI: 6–33, P, Patients with solid cancers have high rates of clonal haematopoiesis associated with increased risk of secondary leukemias. Here, by using peripheral blood sequencing data from patients with solid non-hematologic cancer, the authors profile the landscape of mosaic chromosomal alterations and gene mutations, defining patients at high risk of leukemia progression.

Objectives Negative effusion cytology is more common in certain forms of Malignant Pleural Effusion (MPE) and results in pathway delay. Local Anaesthetic Thoracoscopy (LAT) is extremely sensitive and safe but cannot be offered to all. A stratified pathway, including ‘Direct to LAT’ in selected cases could enhance patient experience but requires reliable baseline predictors of unhelpful cytology, including both negative (no malignant cells) and incomplete results (malignant cells identified but predictive markers failed), since pleural biopsies will be required in the latter for optimal management. This retrospective analysis of a prospective multi-centre study, sought to identify baseline features for pathway rationalization. Materials and methods 363/638 (57%) of patients recruited to the DIAPHRAGM study (ISRCTN10079972) were included. Prospective data, including final diagnoses, asbestos exposure and fluid cytology results were supplemented by retrospective Computed Tomography (CT) and predictive marker reports. Independent predictors of negative and incomplete cytology were determined by multivariable logistic regression. Contingency tables were used to assess diagnostic value of cytology in associated phenotypes. Results 238/363 (66%) patients were diagnosed with MPE (18 tumour types). Fluid cytology was negative in 151/238 (63%) and independently associated with asbestos-exposure (Odds Ratio (OR) 5.34) and a malignant CT (OR 2.25). When both features were recorded the sensitivity and negative predictive value of fluid cytology were 19% (95% CI 11–30%) and 9% (95% CI 4–20%)), respectively. Cytology was incomplete in 34/238 (14%), i.e. 47% of positive cytology cases) but was not associated with any baseline feature. ORs for incomplete cytology in Ovarian, Breast, Renal and Lung Cancer were 83, 22, 21 and 9, respectively. Conclusion Negative cytology is extremely likely in patients with asbestos exposure and a malignant CT report. A ‘Direct-to-LAT’ approach may be appropriate in this setting. No baseline predictors of incomplete cytology were identified.

PURPOSE Tumor mutational profiling is increasingly performed in patients with advanced cancer. We determined the extent to which germline mutation profiling guides therapy selection in patients with advanced cancer. METHODS Patients with cancer undergoing tumor genomic profiling were prospectively consented for germline cancer predisposition gene analysis (2015-2019). In patients harboring germline likely pathogenic or pathogenic (LP/P) alterations, therapeutic actionability was classified using a precision oncology knowledge base. Patients with metastatic or recurrent cancer receiving germline genotype–directed therapy were determined. RESULTS Among 11,947 patients across > 50 malignancies, 17% (n = 2,037) harbored a germline LP/P variant. By oncology knowledge base classification, 9% (n = 1042) had an LP/P variant in a gene with therapeutic implications (4% level 1; 4% level 3B; < 1% level 4). BRCA1/2 variants accounted for 42% of therapeutically actionable findings, followed by CHEK2 (13%), ATM (12%), mismatch repair genes (11%), and PALB2 (5%). When limited to the 9,079 patients with metastatic or recurrent cancer, 8% (n = 710) harbored level 1 or 3B genetic findings and 3.2% (n = 289) received germline genotype–directed therapy. Germline genotype–directed therapy was received by 61% and 18% of metastatic cancer patients with level 1 and level 3B findings, respectively, and by 54% of BRCA1/2, 75% of mismatch repair, 43% of PALB2, 35% of RAD51C/D, 24% of BRIP1, and 19% of ATM carriers. Of BRCA1/2 patients receiving a poly(ADP-ribose) polymerase inhibitor, 45% (84 of 188) had tumors other than breast or ovarian cancer, wherein the drug, at time of delivery, was delivered in an investigational setting. CONCLUSION In a pan-cancer analysis, 8% of patients with advanced cancer harbored a germline variant with therapeutic actionability with 40% of these patients receiving germline genotype–directed treatment. Germline sequence analysis is additive to tumor sequence analysis for therapy selection and should be considered for all patients with advanced cancer.

Reports suggest an increased risk of tuberculosis (TB) in people with chronic airway diseases (CADs) such as chronic obstructive pulmonary disease (COPD), but evidence has not been systematically reviewed. We performed a systematic review by searching MEDLINE and Embase for studies published from 1 January 1993 to 15 January 2021 reporting the association between the incident risk of TB in people with CADs (asthma, COPD and bronchiectasis). Two reviewers independently assessed the quality of individual studies. We included nine studies, with two from low-income high TB burden countries. Three cohort studies reported a statistically significant independent association between COPD and the risk of TB in high-income countries (n=711 389). Hazard ratios for incident TB ranged from 1.44 to 3.14 adjusted for multiple confounders including age, sex and comorbidity. There was large between-study heterogeneity (I2=97.0%) across studies. The direction of effect on the TB risk from asthma was inconsistent. Chronic bronchitis or bronchiectasis studies were limited. The small number of available studies demonstrated an increased risk of TB in people with COPD; however, the magnitude of the increase varies by setting and population. Data in high TB burden countries and for other CADs are limited.

Purpose: We report our experience with next-generation sequencing to characterize the landscape of actionable genomic alterations in renal cell carcinoma (RCC). Experimental Design: A query of our institutional clinical sequencing database (MSK-IMPACT) was performed that included tumor samples from 38,468 individuals across all cancer types. Somatic variations were annotated using a precision knowledge database (OncoKB) and the available clinical data stratified by level of evidence. Alterations associated with response to immune-checkpoint blockade (ICB) were analyzed separately; these included DNA mismatch repair (MMR) gene alterations, tumor mutational burden (TMB), and microsatellite instability (MSI). Data from The Cancer Genome Atlas (TCGA) consortium as well as public data from several clinical trials in metastatic RCC were used for validation purposes. Multiregional sequencing data from the TRAcking Cancer Evolution through Therapy (TRACERx) RENAL cohort were used to assess the clonality of somatic mutations. Results: Of the 753 individuals with RCC identified in the MSK-IMPACT cohort, 115 showed evidence of targetable alterations, which represented a prevalence of 15.3% [95% confidence interval (CI), 12.7%–17.8%). When stratified by levels of evidence, the alterations identified corresponded to levels 2 (11.3%), 3A (5.2%), and 3B (83.5%). A low prevalence was recapitulated in the TCGA cohort at 9.1% (95% CI, 6.9%–11.2%). Copy-number variations predominated in papillary RCC tumors, largely due to amplifications in the MET gene. Notably, higher rates of actionability were found in individuals with metastatic disease (stage IV) compared with those with localized disease (OR, 2.50; 95% CI, 1.16–6.16; Fisher's P = 0.01). On the other hand, the prevalence of alterations associated with response to ICB therapy was found to be approximately 5% in both the MSK-IMPACT and TCGA cohorts and no associations with disease stage were identified (OR, 1.35; 95% CI, 0.46–5.40; P = 0.8). Finally, multiregional sequencing revealed that the vast majority of actionable mutations occurred later during tumor evolution and were only present subclonally in RCC tumors. Conclusions: RCC harbors a low prevalence of clinically actionable alterations compared with other tumors and the evidence supporting their clinical use is limited. These aberrations were found to be more common in advanced disease and seem to occur later during tumor evolution. Our study provides new insights on the role of targeted therapies for RCC and highlights the need for additional research to improve treatment selection using genomic profiling.

Summary Background Bronchiectasis is predominantly a neutrophilic inflammatory disease. There are no established therapies that directly target neutrophilic inflammation because little is understood of the underlying mechanisms leading to severe disease. Neutrophil extracellular trap (NET) formation is a method of host defence that has been implicated in multiple inflammatory diseases. We aimed to investigate the role of NETs in disease severity and treatment response in bronchiectasis. Methods In this observational study, we did a series of UK and international studies to investigate the role of NETs in disease severity and treatment response in bronchiectasis. First, we used liquid chromatography-tandem mass spectrometry to identify proteomic biomarkers associated with disease severity, defined using the bronchiectasis severity index, in patients with bronchiectasis (n=40) in Dundee, UK. Second, we validated these biomarkers in two cohorts of patients with bronchiectasis, the first comprising 175 patients from the TAYBRIDGE study in the UK and the second comprising 275 patients from the BRIDGE cohort study from centres in Italy, Spain, and UK, using an immunoassay to measure NETs. Third, we investigated whether pathogenic bacteria had a role in NET concentrations in patients with severe bronchiectasis. In a separate study, we enrolled patients with acute exacerbations of bronchiectasis (n=20) in Dundee, treated with intravenous antibiotics for 14 days and proteomics were used to identify proteins associated with treatment response. Findings from this cohort were validated in an independent cohort of patients who were admitted to the same hospital (n=20). Fourth, to assess the potential use of macrolides to reduce NETs in patients with bronchiectasis, we examined two studies of long-term macrolide treatment, one in patients with bronchiectasis (n=52 from the UK) in which patients were given 250 mg of azithromycin three times a week for a year, and a post-hoc analysis of the Australian AMAZES trial in patients with asthma (n=47) who were given 500 mg of azithromycin 3 times per week for a year. Findings Sputum proteomics identified that NET-associated proteins were the most abundant and were the proteins most strongly associated with disease severity. This finding was validated in two observational cohorts, in which sputum NETs were associated with bronchiectasis severity index, quality of life, future risk of hospital admission, and mortality. In a subgroup of 20 patients with acute exacerbations, clinical response to intravenous antibiotic treatment was associated with successfully reducing NETs in sputum. Patients with Pseudomonas aeruginosa infection had a lessened proteomic and clinical response to intravenous antibiotic treatment compared with those without Pseudomonas infections, but responded to macrolide therapy. Treatment with low dose azithromycin was associated with a significant reduction in NETs in sputum over 12 months in both bronchiectasis and asthma. Interpretation We identified NETs as a key marker of disease severity and treatment response in bronchiectasis. These data support the concept of targeting neutrophilic inflammation with existing and novel therapies. Funding Scottish Government, British Lung Foundation, and European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC).

Neutrophil elastase (NE) is a 29kDa serine protease released from the azurophilic granules of neutrophils. It may be directly involved in the pathogenesis and disease progression in cystic fibrosis, bronchiectasis and COPD through the degradation of airway elastin and by impairing host defence. Areas covered: Measurement of NE activity has emerged as a promising biomarker strategy in inflammatory lung disease. The authors review studies where NE activity has been linked with clinical outcomes such as lung function decline, exacerbation frequency or other cross-sectional and longitudinal markers of disease severity. In this article the evidence for NE measurement, and the strengths and weaknesses of a commercially available immunoassay which can specifically detect NE activity in human biological samples such as sputum and bronchoalveolar lavage are reviewed. Expert commentary: NE is a promising biomarker for stratifying severity disease. NE also appears to be responsive to antibiotic and other treatments, potentially therefore allowing it to be used as an indicator of treatment response in clinical trials.

There is conflicting data regarding the role of PBAF complex mutations and response to immune checkpoint blockade (ICB) therapy in clear cell renal cell carcinoma (ccRCC) and other solid tumors. We assess the prevalence of PBAF complex mutations from two large cohorts including the pan-cancer TCGA project (n = 10,359) and the MSK-IMPACT pan-cancer immunotherapy cohort (n = 3700). Across both cohorts, PBAF complex mutations, predominantly PBRM1 mutations, are most common in ccRCC. In multivariate models of ccRCC patients treated with ICB (n = 189), loss-of-function (LOF) mutations in PBRM1 are not associated with overall survival (OS) (HR = 1.24, p = 0.47) or time to treatment failure (HR = 0.85, p = 0.44). In a series of 11 solid tumors (n = 2936), LOF mutations are not associated with improved OS in a stratified multivariate model (HR = 0.9, p = 0.7). In a current series of solid tumors treated with ICB, we are unable to demonstrate favorable response to ICB in patients with PBAF complex mutations.

Background The sputum microbiome has a potential role in disease phenotyping and risk stratification in chronic obstructive pulmonary disease (COPD), but few large longitudinal cohort studies exist. Objective Our aim was to investigate the COPD sputum microbiome and its association with inflammatory phenotypes and mortality. Methods 16S ribosomal RNA gene sequencing was performed on sputum from 253 clinically stable COPD patients (4-year median follow-up). Samples were classified as Proteobacteria or Firmicutes (phylum level) and Haemophilus or Streptococcus (genus level) dominant. Alpha diversity was measured by using Shannon-Wiener diversity and Berger-Parker dominance indices. Survival was modeled by using Cox proportional hazards regression. A subset of 78 patients had label-free liquid chromatography with tandem mass spectrometry performed, with partial least square discriminant analysis integrating clinical, microbiome, and proteomics data. Results Proteobacteria dominance and lower diversity was associated with more severe COPD according to the Global Initiative for Chronic Obstructive Lung Disease classification system (P = .0015), more frequent exacerbations (P = .0042), blood eosinophil level less than or equal to 100 cells/μL (P Conclusion The sputum microbiome is associated with clinical and inflammatory phenotypes in COPD. Reduced microbiome diversity, associated with Proteobacteria (predominantly Haemophilus) dominance, is associated with neutrophil-associated protein profiles and an increased risk of mortality.

The anti-HER2 antibody trastuzumab is standard care for advanced esophagogastric (EG) cancer with ERBB2 (HER2) amplification or overexpression, but intrinsic and acquired resistance are common. We conducted a phase II study of afatinib, an irreversible pan-HER kinase inhibitor, in trastuzumab-resistant EG cancer. We analyzed pretreatment tumor biopsies and, in select cases, performed comprehensive characterization of postmortem metastatic specimens following acquisition of drug resistance. Afatinib response was associated with coamplification of EGFR and ERBB2. Heterogeneous 89Zr-trastuzumab PET uptake was associated with genomic heterogeneity and mixed clinical response to afatinib. Resistance to afatinib was associated with selection for tumor cells lacking EGFR amplification or with acquisition of MET amplification, which could be detected in plasma cell-free DNA. The combination of afatinib and a MET inhibitor induced complete tumor regression in ERBB2 and MET coamplified patient-derived xenograft models established from a metastatic lesion progressing on afatinib. Collectively, differential intrapatient and interpatient expression of HER2, EGFR, and MET may determine clinical response to HER kinase inhibitors in ERBB2-amplified EG cancer. Significance: Analysis of patients with ERBB2-amplified, trastuzumab-resistant EG cancer who were treated with the HER kinase inhibitor afatinib revealed that sensitivity and resistance to therapy were associated with EGFR/ERBB2 coamplification and MET amplification, respectively. HER2-directed PET imaging and cell-free DNA sequencing could help guide strategies to overcome the emergence of resistant clones. See related commentary by Klempner and Catenacci, p. 166. This article is highlighted in the In This Issue feature, p. 151

Background/Objectives Infantile hemangiomas (IHs) are vascular tumors with the potential for significant morbidity. There is a lack of validated objective tools to assess IH severity and response to treatment. Diffuse optical spectroscopy (DOS), a noninvasive, nonionizing imaging modality, can measure total hemoglobin concentration and hemoglobin oxygen saturation in tissue to assess IH vascularity and response to treatment. Our objective was to evaluate the utility of a wireless, handheld DOS system to assess IH characteristics at selected points during their clinical course. Methods Thirteen subjects (initial age 5.8 ± 2.0 mos) with 15 IHs were enrolled. IHs were classified as proliferative, plateau phase, or involuting. Nine patients with 11 IHs were untreated; four patients with 4 IHs were treated with timolol or propranolol. Each IH was evaluated by placing the DOS system directly on the lesion as well a normal contralateral skin site. IH vascularity and oxygenation were scored using a newly defined normalized hypoxia fraction (NHF) coefficient. Measurements were recorded at various intervals from the initial visit to 1 to 2 years of age. Results For the nine untreated IHs, the NHF was highest at 6 months of age, during proliferation. Differences in NHFs between the proliferation and the plateau (p = 0.02) and involuting (p < 0.001) stages were statistically significant. In treated patients, the NHF normalized to 60% after 2 months. One treated IH came within 5% of the NHF for normal skin after 12 months. Conclusions DOS can be used to assess the vascularity and tissue oxygenation of IHs and monitor their progression and response to treatment.

Background Neutrophil extracellular traps (NETs) have been observed in the airway in patients with chronic obstructive pulmonary disease (COPD), but their clinical and pathophysiologic implications have not been defined. Objective We sought to determine whether NETs are associated with disease severity in patients with COPD and how they are associated with microbiota composition and airway neutrophil function. Methods NET protein complexes (DNA-elastase and histone-elastase complexes), cell-free DNA, and neutrophil biomarkers were quantified in soluble sputum and serum from patients with COPD during periods of disease stability and during exacerbations and compared with clinical measures of disease severity and the sputum microbiome. Peripheral blood and airway neutrophil function were evaluated by means of flow cytometry ex vivo and experimentally after stimulation of NET formation. Results Sputum NET complexes were associated with the severity of COPD evaluated by using the composite Global Initiative for Obstructive Lung Disease scale (P, Graphical abstract

Diffuse optical tomography has shown promising results as a tool for breast cancer screening and monitoring response to chemotherapy. Dynamic imaging of the transient response of the breast to an external stimulus, such as pressure or a respiratory maneuver, can provide additional information that can be used to detect tumors. We present a new digital continuous-wave optical tomography system designed to simultaneously image both breasts at fast frame rates and with a large number of sources and detectors. The system uses a master-slave digital signal processor-based detection architecture to achieve a dynamic range of 160 dB and a frame rate of 1.7 Hz with 32 sources, 64 detectors, and 4 wavelengths per breast. Included is a preliminary study of one healthy patient and two breast cancer patients showing the ability to identify an invasive carcinoma based on the hemodynamic response to a breath hold.

Optical imaging has the potential to play a major role in breast cancer screening and diagnosis due to its ability to image cancer characteristics such as angiogenesis and hypoxia. A promising approach to evaluate and quantify these characteristics is to perform dynamic imaging studies in which one monitors the hemodynamic response to an external stimulus, such as a valsalva maneuver. It has been shown that the response to such stimuli shows MARKED differences between cancerous and healthy tissues. The fast imaging rates and large dynamic range of digital devices makes them ideal for this type of imaging studies. Here we present a digital optical tomography system designed specifically for dynamic breast imaging. The instrument uses laser diodes at 4 different near-infrared wavelengths with 32 sources and 128 silicon photodiode detectors.

Dynamic optical imaging is increasingly applied to clinically relevant areas such as brain and cancer imaging. In this approach, some external stimulus is applied and changes in relevant physiological parameters (e.g., oxy- or deoxyhemoglobin concentrations) are determined. The advantage of this approach is that the prestimulus state can be used as a reference or baseline against which the changes can be calibrated. Here we present the first application of this method to the problem of characterizing joint diseases, especially effects of rheumatoid arthritis (RA) in the proximal interphalangeal finger joints. Using a dual-wavelength tomographic imaging system together with previously implemented model-based iterative image reconstruction schemes, we have performed initial dynamic imaging case studies on a limited number of healthy volunteers and patients diagnosed with RA. Focusing on three cases studies, we illustrated our major finds. These studies support our hypothesis that differences in the vascular reactivity exist between affected and unaffected joints.