Reza Forghani

Origins of tumor-associated macrophages and neutrophils

Tumor-associated macrophages (TAMs) and tumor-associated neutrophils (TANs) can control cancer growth and exist in almost all solid neoplasms. The cells are known to descend from immature monocytic and granulocytic cells, respectively, which are produced in the bone marrow. However, the spleen is also a recently identified reservoir of monocytes, which can play a significant role in the inflammatory response that follows acute injury. Here, we evaluated the role of the splenic reservoir in a genetic mouse model of lung adenocarcinoma driven by activation of oncogenic Kras and inactivation of p53. We found that high numbers of TAM and TAN precursors physically relocated from the spleen to the tumor stroma, and that recruitment of tumor-promoting spleen-derived TAMs required signaling of the chemokine receptor CCR2. Also, removal of the spleen, either before or after tumor initiation, reduced TAM and TAN responses significantly and delayed tumor growth. The mechanism by which the spleen was able to maintain its reservoir capacity throughout tumor progression involved, in part, local accumulation in the splenic red pulp of typically rare extramedullary hematopoietic stem and progenitor cells, notably granulocyte and macrophage progenitors, which produced CD11b+ Ly-6Chi monocytic and CD11b+ Ly-6Ghi granulocytic cells locally. Splenic granulocyte and macrophage progenitors and their descendants were likewise identified in clinical specimens. The present study sheds light on the origins of TAMs and TANs, and positions the spleen as an important extramedullary site, which can continuously supply growing tumors with these cells.

Automatic Quantification of MS Lesions in 3D MRI Brain Data Sets: Validation of INSECT

In recent years, the quantitative analysis of MRI data has become a standard surrogate marker in clinical trials in multiple sclerosis (MS). We have developed INSECT (Intensity Normalized Stereotaxic Environment for Classification of Tissues), a fully automatic system aimed at the quantitative morphometric analysis of 3D MRI brain data sets. This paper describes the design and validation of INSECT in the context of a multi-center clinical trial in MS. It is shown that no statistically significant differences exist between MS lesion load measurements obtained with INSECT and those obtained manually by trained human observers from seven different clinical centers.

Measuring Myeloperoxidase Activity in Biological Samples

Background Enzymatic activity measurements of the highly oxidative enzyme myeloperoxidase (MPO), which is implicated in many diseases, are widely used in the literature, but often suffer from nonspecificity and lack of uniformity. Thus, validation and standardization are needed to establish a robust method that is highly specific, sensitive, and reproducible for assaying MPO activity in biological samples. Principal findings We found conflicting results between in vivo molecular MR imaging of MPO, which measures extracellular activity, and commonly used in vitro MPO activity assays. Thus, we established and validated a protocol to obtain extra- and intracellular MPO from murine organs. To validate the MPO activity assays, three different classes of MPO activity assays were used in spike and recovery experiments. However, these assay methods yielded inconsistent results, likely because of interfering substances and other peroxidases present in tissue extracts. To circumvent this, we first captured MPO with an antibody. The MPO activity of the resultant samples was assessed by ADHP and validated against samples from MPO-knockout mice in murine disease models of multiple sclerosis, steatohepatitis, and myocardial infarction. We found the measurements performed using this protocol to be highly specific and reproducible, and when performed using ADHP, to be highly sensitive over a broad range. In addition, we found that intracellular MPO activity correlated well with tissue neutrophil content, and can be used as a marker to assess neutrophil infiltration in the tissue. Conclusion We validated a highly specific and sensitive assay protocol that should be used as the standard method for all MPO activity assays in biological samples. We also established a method to obtain extra- and intracellular MPO from murine organs. Extracellular MPO activity gives an estimate of the oxidative stress in inflammatory diseases, while intracellular MPO activity correlates well with tissue neutrophil content. A detailed step-by-step protocol is provided.

Ocular Adnexal Lymphoma: Diffusion-weighted MR Imaging for Differential Diagnosis and Therapeutic Monitoring

PURPOSE To describe the magnetic resonance (MR) imaging and diffusion-weighted (DW) imaging features of ocular adnexal lymphomas (OALs), to determine the diagnostic accuracy of apparent diffusion coefficient (ADC) for discriminating OALs from other orbital mass lesions, and to assess whether variations in ADC constitute a reliable biomarker of OAL response to therapy. MATERIALS AND METHODS Institutional ethical committee approval and informed consent were obtained. In this prospective study, 114 white subjects (65 females and 49 males) were enrolled. Thirty-eight patients with histopathologically proved OAL underwent serial MR and DW imaging examination of the orbits. ADCs of OALs were compared with those of normal orbital structures, obtained in 18 healthy volunteers, and other orbital mass lesions, prospectively acquired in 58 patients (20 primary non-OAL neoplasms, 15 vascular benign lesions, 12 inflammatory lesions, 11 metastases). Interval change in ADC of OALs before and after treatment was analyzed in 29 patients. Analysis of covariance and a paired t test were used for statistical analysis. RESULTS Baseline ADCs in OALs were lower than those in normal structures and other orbital diseases (P < .001). An ADC threshold of 775 x 10(-6) mm(2)/sec resulted in 96% sensitivity, 93% specificity, 88% positive predictive value, 98.2% negative predictive value, and 94.4% accuracy in OAL diagnosis. Following appropriate treatment, 10 (34%) of 29 patients showed OAL volumetric reduction, accompanied (n = 7) or preceded (n = 3) by an increase in ADC (P = .005). Conversely, a further reduction of ADC was observed in the seven patients who experienced disease progression (P < .05). CONCLUSION ADC permits accurate diagnosis of OALs. Interval change in ADC after therapy represents a helpful tool for predicting therapeutic response.

Functional Organization of a Schwann Cell Enhancer

Myelin basic protein (MBP) gene expression is conferred in oligodendrocytes and Schwann cells by different upstream enhancers. In Schwann cells, expression is controlled by a 422 bp enhancer lying -9 kb from the gene. We show here that it contains 22 mammalian conserved motifs ≥6 bp. To investigate their functional significance, different combinations of wild-type or mutated motifs were introduced into reporter constructs that were inserted in single copy at a common hypoxanthine phosphoribosyltransferase docking site in embryonic stem cells. Lines of transgenic mice were derived, and the subsequent qualitative and quantitative expression phenotypes were compared at different stages of maturation. In the enhancer core, seven contiguous motifs cooperate to confer Schwann cell specificity while different combinations of flanking motifs engage, at different stages of Schwann cell maturation, to modulate expression level. Mutation of a Krox-20 binding site reduces the level of reporter expression, whereas mutation of a potential Sox element silences reporter expression. This potential Sox motif was also found conserved in other Schwann cell enhancers, suggesting that it contributes widely to regulatory function. These results demonstrate a close relationship between phylogenetic footprints and regulatory function and suggest a general model of enhancer organization. Finally, this investigation demonstrates that in vivo functional analysis, supported by controlled transgenesis, can be a robust complement to molecular and bioinformatics approaches to regulatory mechanisms.

Optimal Virtual Monochromatic Images for Evaluation of Normal Tissues and Head and Neck Cancer Using Dual-Energy CT

BACKGROUND AND PURPOSE: Dual-energy CT is not used routinely for evaluation of the head and neck, and there is no consensus on the optimal virtual monochromatic image energies for evaluating normal tissues or head and neck cancer. We performed a quantitative evaluation to determine the optimal virtual monochromatic images for visualization of normal tissues, head and neck squamous cell carcinoma, and lymphadenopathy. MATERIALS AND METHODS: Dual-energy CT scans from 10 healthy patients and 30 patients with squamous cell carcinoma were evaluated at different virtual monochromatic energy levels ranging from 40 to 140 keV. The signal-to-noise ratios of muscles at 6 different levels, glands (parotid, sublingual, submandibular, and thyroid), 30 tumors, and 17 metastatic lymph nodes were determined as measures of optimal image quality. Lesion attenuation and contrast-to-noise ratios (compared with those of muscle) were evaluated to assess lesion conspicuity. RESULTS: The optimal signal-to-noise ratio for all the tissues was at 65 keV (P < .0001). However, tumor attenuation (P < .0001), attenuation difference between tumor and muscles (P = .03), and lesion contrast-to-noise ratios (P < .0001) were highest at 40 keV. CONCLUSIONS: The optimal image signal-to-noise ratio is at 65 keV, but tumor conspicuity compared with that of muscle is greatest at 40 keV. Optimal evaluation of the neck may be best achieved by a multiparametric approach, with 65-keV virtual monochromatic images providing the best overall image quality and targeted use of 40-keV virtual monochromatic images for tumor evaluation.

Novel Diagnostic Approaches in Bing-Neel Syndrome

The central nervous system (CNS) manifestations of Waldenströms macroglobulinemia (WM) are known as the Bing-Neel syndrome (BNS). Patients with BNS can be classified into Group A and Group B based on the presence of lymphoplasmacytoid (LMP) cells within the brain parenchyma, leptomeninges, dura, and/or cerebrospinal fluid (CSF). To identify characteristic imaging findings for both Group A and Group B patients, we reviewed all 36 cases (26 referenced, 10 unreported) of proven WM with CNS symptoms, CSF analysis and/or biopsy, and magnetic resonance imaging (MRI) of the brain and/or spinal cord. Enhancement on MRI suggests invasion of the central neuraxis by LMP cells, and can help distinguish between Group A and Group B patients. In addition to differentiating true WM lesions in the CNS from ischemia, hyperviscosity events, and demyelinating lesions, evaluation of brain and spinal cord with gadolinium-enhanced MRI has the potential to guide management.

Multiparametric Evaluation of Head and Neck Squamous Cell Carcinoma Using a Single-Source Dual-Energy CT with Fast kVp Switching: State of the Art

There is an increasing body of evidence establishing the advantages of dual-energy CT (DECT) for evaluation of head and neck squamous cell carcinoma (HNSCC). Focusing on a single-source DECT system with fast kVp switching, we will review the principles behind DECT and associated post-processing steps that make this technology especially suitable for HNSCC evaluation and staging. The article will review current applications of DECT for evaluation of HNSCC including use of different reconstructions to improve tumor conspicuity, tumor-normal soft tissue interface, accuracy of invasion of critical structures such as thyroid cartilage, and reduce dental artifact. We will provide a practical approach for DECT implementation into routine clinical use and a multi-parametric approach for scan interpretation based on the experience at our institution. The article will conclude with a brief overview of potential future applications of the technique.

Different Spectral Hounsfield Unit Curve and High-Energy Virtual Monochromatic Image Characteristics of Squamous Cell Carcinoma Compared with Nonossified Thyroid Cartilage

BACKGROUND AND PURPOSE: The attenuation of normal nonossified thyroid cartilage can be similar to that of head and neck squamous cell carcinoma on CT. We compared dual-energy CT spectral Hounsfield unit attenuation characteristics of nonossified thyroid cartilage with that of squamous cell carcinoma to determine the optimal virtual monochromatic image reconstruction energy levels for distinguishing tumor from normal nonossified thyroid cartilage. MATERIALS AND METHODS: Dual-energy CT scans from 30 patients with histopathology-proved squamous cell carcinoma at different primary sites (laryngeal and nonlaryngeal) and 10 healthy patients were evaluated. Patients were scanned with a 64-section single-source scanner with fast-kilovolt (peak) switching, and scans were reconstructed at different virtual monochromatic energy levels ranging from 40 to 140 keV. Spectral attenuation curves of tumor and nonossified thyroid cartilage were quantitatively evaluated and compared. Any part of the tumor invading the cartilage, when present, was excluded from ROI analysis to avoid cross-contamination from areas where there could be a mixture of cartilage and invading tumor. RESULTS: Normal nonossified thyroid cartilage had a characteristic, predictable spectral attenuation curve that was different from that of tumors. The greatest difference in attenuation of nonossified cartilage compared with tumor was on virtual monochromatic images of ≥95 keV (P < .0001), with sharp contrast between the relatively high attenuation of nonossified cartilage compared with that of tumor. CONCLUSIONS: Head and neck squamous cell carcinoma has significantly different attenuation on virtual monochromatic images of ≥95 keV, compared with nonossified thyroid cartilage.

Advanced dual-energy CT for head and neck cancer imaging

Dual energy computed tomography (DECT) is an advanced form of computed tomography (CT) in which simultaneous or near-simultaneous acquisitions are performed at two different peak energy levels, enabling material density and spectral attenuation characterization beyond what is possible with conventional CT scans. This article is a review of the current applications of DECT for the evaluation of head and neck cancer. The article will begin with a brief overview of different approaches to DECT scanning and address basic issues related to image quality and acquisition dose. This will be followed by a review of the use of different DECT reconstructions for improving head and neck squamous cell carcinoma visualization, evaluation of tumor extent, and invasion of critical structures. The article will conclude with a brief review of other emerging applications of DECT for evaluation of different head and neck cancers and advanced tumor analysis.