The Scientific World Journal: Molecular Imaging

Molecular Imaging of Experimental Abdominal Aortic Aneurysms

Tue, 23 Apr 2013 11:37:20 +0000

Current laboratory research in the field of abdominal aortic aneurysm (AAA) disease often utilizes small animal experimental models induced by genetic manipulation or chemical application. This has led to the use and development of multiple high-resolution molecular imaging modalities capable of tracking disease progression, quantifying the role of inflammation, and evaluating the effects of potential therapeutics. In vivo imaging reduces the number of research animals used, provides molecular and cellular information, and allows for longitudinal studies, a necessity when tracking vessel expansion in a single animal. This review outlines developments of both established and emerging molecular imaging techniques used to study AAA disease. Beyond the typical modalities used for anatomical imaging, which include ultrasound (US) and computed tomography (CT), previous molecular imaging efforts have used magnetic resonance (MR), near-infrared fluorescence (NIRF), bioluminescence, single-photon emission computed tomography (SPECT), and positron emission tomography (PET). Mouse and rat AAA models will hopefully provide insight into potential disease mechanisms, and the development of advanced molecular imaging techniques, if clinically useful, may have translational potential. These efforts could help improve the management of aneurysms and better evaluate the therapeutic potential of new treatments for human AAA disease.

Perspectives in Molecular Imaging Using Staging Biomarkers and Immunotherapies in Alzheimer’s Disease

Benoît Leclerc and Abedelnasser Abulrob — Tue, 05 Feb 2013 11:03:44 +0000

Sporadic Alzheimer’s disease (AD) is an emerging chronic illness characterized by a progressive pleiotropic pathophysiological mode of actions triggered during the senescence process and affecting the elderly worldwide. The complex molecular mechanisms of AD not only are supported by cholinergic, beta-amyloid, and tau theories but also have a genetic basis that accounts for the difference in symptomatology processes activation among human population which will evolve into divergent neuropathological features underlying cognitive and behaviour alterations. Distinct immune system tolerance could also influence divergent responses among AD patients treated by immunotherapy. The complexity in nature increases when taken together the genetic/immune tolerance with the patient’s brain reserve and with neuropathological evolution from early till advance AD clinical stages. The most promising diagnostic strategies in today’s world would consist in performing high diagnostic accuracy of combined modality imaging technologies using beta-amyloid 42 peptide-cerebrospinal fluid (CSF) positron emission tomography (PET), Pittsburgh compound B-PET, fluorodeoxyglucose-PET, total and phosphorylated tau-CSF, and volumetric magnetic resonance imaging hippocampus biomarkers for criteria evaluation and validation. Early diagnosis is the challenge task that needs to look first at plausible mechanisms of actions behind therapies, and combining them would allow for the development of efficient AD treatment in a near future.

Prevalence of Clinically Significant Extraosseous Findings on Unenhanced CT Portions of 18F-Fluoride PET/CT Bone Scans

Chao-Jung Chen and Shih-Ya Ma — Mon, 10 Sep 2012 14:15:59 +0000

Objective. Due to the frequently interrupted supply of 99mTc-methylene diphosphonate, the use of 18F-fluoride positron emission tomography (PET)/computed tomography (CT) has become more popular. The study aims to determine the percentage of extraosseous findings from the unenhanced CT portion of 18F-fluoride PET/CT scans. Materials and Methods. We retrospectively collected 18F-fluoride PET/CT studies between March 2010 and February 2011. The unenhanced CT portions of 18F-fluoride PET/CT were reviewed for each patient. Significant extraosseous findings related to malignancy from the unenhanced CT were recorded. Results. A total of 158 patients (110 females, 48 males) were included in the study. Clinically significant extraosseous findings from the unenhanced CT were found in 43 patients (27.2%). Previously unknown extraosseous findings were identified in 17 patients (10.8%) after a review of the 18F-fluoride PET/CT scan results. Most of the extraosseous findings were small pulmonary metastases or enlarged metastatic lymph nodes. Conclusion. It is not rare to identify new clinically significant extraosseous findings from the unenhanced CT of 18F-fluoride PET/CT studies. Therefore the clinical management of patients may be altered by the results, and a careful review of the unenhanced CT portion of 18F-fluoride PET/CT is mandatory.

Correlation of Dynamic PET and Gene Array Data in Patients with Gastrointestinal Stromal Tumors

Mon, 04 Jun 2012 15:42:30 +0000

Introduction. The results obtained with dynamic PET (dPET) were compared to gene expression data obtained in patients with gastrointestinal stromal tumors (GIST). The primary aim was to assess the association of the dPET results and gene expression data. Material and Methods. dPET was performed following the injection of F-18-fluorodeoxyglucose (FDG) in 22 patients with GIST. All patients were examined prior to surgery for staging purpose. Compartment and noncompartment models were used for the quantitative evaluation of the dPET examinations. Gene array data were based on tumor specimen obtained by surgery after the PET examinations. Results. The data analysis revealed significant correlations for the dPET parameters and the expression of zinc finger genes (znf43, znf85, znf91, znf189). Furthermore, the transport of FDG (k1) was associated with VEGF-A. The cell cycle gene cyclin-dependent kinase inhibitor 1C was correlated with the maximum tracer uptake (SUVmax) in the tumors. Conclusions. The data demonstrate a dependency of the tracer kinetics on genes associated with prognosis in GIST. Furthermore, angiogenesis and cell proliferation have an impact on the tracer uptake.

SPECT and PET Imaging of Meningiomas

Tue, 01 May 2012 15:43:03 +0000

Meningiomas arise from the meningothelial cells of the arachnoid membranes. They are the most common primary intracranial neoplasms and represent about 20% of all intracranial tumors. They are usually diagnosed after the third decade of life and they are more frequent in women than in men. According to the World Health Organization (WHO) criteria, meningiomas can be classified into grade I meningiomas, which are benign, grade II (atypical) and grade III (anaplastic) meningiomas, which have a much more aggressive clinical behaviour. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are routinely used in the diagnostic workup of patients with meningiomas. Molecular Nuclear Medicine Imaging with Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) could provide complementary information to CT and MRI. Various SPECT and PET tracers may provide information about cellular processes and biological characteristics of meningiomas. Therefore, SPECT and PET imaging could be used for the preoperative noninvasive diagnosis and differential diagnosis of meningiomas, prediction of tumor grade and tumor recurrence, response to treatment, target volume delineation for radiation therapy planning, and distinction between residual or recurrent tumour from scar tissue.

Review Analysis of the Association between the Prevalence of Activated Brown Adipose Tissue and Outdoor Temperature

Thu, 19 Apr 2012 13:12:48 +0000

Brown adipose tissue (BAT) is important for regulating body weight. Environmental temperature influences BAT activation. Activated BAT is identifiable using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). 18F-FDG PET/CT scans done between June 2005 and May 2009 in our institution in tropical southern Taiwan and BAT studies from PubMed (2002–2011) were reviewed, and the average outdoor temperatures during the study periods were obtained. A simple linear regression was used to analyze the association between the prevalence of activated BAT (𝑃) and the average outdoor temperature (𝑇). The review analysis for 9 BAT studies (𝑛=16,765) showed a significant negative correlation (𝑟=−0.741, 𝑃=0.022) between the prevalence of activated BAT and the average outdoor temperature. The equation of the regression line is 𝑃(%)=6.99−0.20×𝑇(∘C). The prevalence of activated BAT decreased by 1% for each 5∘C increase in average outdoor temperature. In a neutral ambient temperature, the prevalence of activated BAT is low and especially rare in the tropics. There is a significant linear negative correlation between the prevalence of activated BAT and the average outdoor temperature.

Investigation of Dose Minimisation Protocol for 18F-FDG PET-CT in the Management of Lymphoma Postchemotherapy Followup

L. I. Sonoda, B. Sanghera, and W. L. Wong — Sun, 01 Apr 2012 09:25:20 +0000

Introduction. 18F-FDG-PET-CT plays an important role in the management of lymphoma postchemotherapy followup. Some centres perform prechemotherapy baseline CT and postchemotherapy PETCT. With a concern of radiation burden, especially in young patients, this study aimed to assess if PETCT radiation dose could be reduced. Methods. Retrospective analysis of 100 lymphoma patients was performed to record sites of disease on prechemotherapy CT and postchemotherapy PETCT. The potential reduction in radiation and time achieved with PETCT limited to sites of known disease identified on prechemotherapy CT was calculated. Results. No FDG-uptake was seen in 72 cases. FDG uptake at known disease sites was seen in 24. Of the remaining 4, one had clinically significant pathology, a rectal adenocarcinoma. PETCT did not reveal any unexpected sites of lymphoma. Limiting PETCT to sites of known disease would have saved a mean radiation dose of 4 mSv (27.3%), with a mean time of 16 minutes. Conclusion. Our study suggests that young patients may benefit from reduced radiation by limiting PETCT to sites of known disease with low risk of missing significant pathology. However, in older patients, with increased incidence of asymptomatic synchronous malignancies, whole-body PETCT is advisable unless prechemotherapy PETCT has been performed.

DWI-MRI: Single, Informative, and Noninvasive Technique for Prostate Cancer Diagnosis

Tue, 14 Feb 2012 15:24:02 +0000

Aim. To evaluate diffusion weighted image-MRI (DWI) as a single diagnostic noninvasive MRI technique for prostate cancer (PCa) diagnosis. Material and Methods. A prospective study was conducted between July 2008 and July 2009. Candidates patients were equal or more than 40 years old, with suspicious digital rectal examination (more than clinical T2) or PSA >4 ng/mL. Informed consent was signed. DWI-MRI was performed at 1.5 T with a body coil combined with a spine coil in consecutive 100 cases. The histopathology of biopsies has been used as reference standard. Two examiners were evaluating MRI and TRUS, both of them were blinded regarding pathological findings. Accuracy, specificity, and sensitivity were statistically analyzed. Results. Based on pathological diagnosis: group A (cancerous); 75 cases and group B (non-cancerous); 25 cases. Mean age was 65.3 and 62.8 years in groups A and B, respectively. Mean PSA was 30.7 and 9.2 ng/mL in groups A and B, respectively. Sensitivity of DWI was 58.3% while specificity was 83.8%. Accuracy of lesion detection was 52.4–77.8% (𝑃<0.05). Moreover, DWI at ADC value 1.2×10−3 mL/sec could determine 82.4% of true positive cases (𝑃<0.05). ADC values were lower with Gleason score ≥7 (𝑃<0.05). Conclusion. DWI could represent a non invasive single diagnostic tool not only in detection and localization but also in prediction of Gleason score whenever DWI is used prior to invasive TRUS biopsy. Furthermore, targeted single biopsy could be planned after DWI to minimize patient morbidity by invasive techniques.

The Usefulness of the Source Images of Magnetic Resonance Angiogram in the Carotid Cavernous Fistula

Bon D. Ku, Hak Yiung Rhee, and Sung Sang Yoon — Mon, 02 Jan 2012 00:00:00 +0000

Confocal Imaging: Blood and Lymphatic Capillaries

Yingjie Cui — Mon, 01 Jan 1900 00:00:00 +0000

Traditional imaging techniques are quite limited for the study of the relationship between blood vessels and lymphatic vessels. Therefore, a new imaging technique is required based on blood vessel and lymphatic endothelial-specific molecular markers. In this short report, vascular molecular markers are reviewed and a new molecular imaging technique for blood vessel and lymphatic co-staining is introduced.

Digital Three-Dimensional Atlas of Quail Development Using High-Resolution MRI

Mon, 01 Jan 1900 00:00:00 +0000

We present an archetypal set of three-dimensional digital atlases of the quail embryo based on microscopic magnetic resonance imaging (μMRI). The atlases are composed of three modules: (1) images of fixed ex ovo quail, ranging in age from embryonic day 5 to 10 (e05 to e10); (2) a coarsely delineated anatomical atlas of the μMRI data; and (3) an organ system-based hierarchical graph linked to the anatomical delineations. The atlas is designed to be accessed using SHIVA, a free Java application. The atlas is extensible and can contain other types of information including anatomical, physiological, and functional descriptors. It can also be linked to online resources and references. This digital atlas provides a framework to place various data types, such as gene expression and cell migration data, within the normal three-dimensional anatomy of the developing quail embryo. This provides a method for the analysis and examination of the spatial relationships among the different types of information within the context of the entire embryo.

Nanoparticles and Inflammation

Ross Stevenson, Axel J. Hueber, Alan Hutton, Iain B. McInnes, and Duncan Graham — Mon, 01 Jan 1900 00:00:00 +0000

The development of nanoscale molecular probes capable of diagnosis, characterization, and clinical treatment of disease is leading to a new generation of imaging technologies. Such probes are particularly relevant to inflammation, where the detection of subclinical, early disease states could facilitate speedier detection that could yield enhanced, tailored therapies. Nanoparticles offer robust platforms capable of sensitive detection, and early research has indicated their suitability for the detection of vascular activation and cellular recruitment at subclinical levels. This suggests that nanoparticle techniques may provide excellent biomarkers for the diagnosis and progression of inflammatory diseases with magnetic resonance imaging (MRI), fluorescent quantum dots (QDs), and surface enhanced Raman scattering (SERS) probes being just some of the new methodologies employed. Development of these techniques could lead to a range of sensitive probes capable of ultrasensitive, localized detection of inflammation. This article will discuss the merits of each approach, with a general overview to their applicability in inflammatory diseases.

Imaging of Bone Marrow Involvement in Lymphoma: State of the Art and Future Directions

Thomas C. Kwee, John M. H. de Klerk, and Rutger A. J. Nievelstein — Mon, 01 Jan 1900 00:00:00 +0000

Accurate detection of bone marrow involvement in patients with lymphoma is of crucial importance because of the prognostic and therapeutic consequences. Bone marrow trephine biopsy (BMB) is currently regarded as the method of choice for the evaluation of the bone marrow in lymphoma, but it is invasive, has a risk of complications, and lacks sufficient sensitivity due to the possibility of sampling errors. Bone marrow imaging, if accurate, may (partially) replace BMBand/or may improve the sensitivity of BMB by guiding the biopsy to the location that appears to be involved by lymphoma at imaging. In this scientific communication, general concepts of bone marrow imaging, state-of-the-art imaging modalities, and future imaging strategies for the assessment of the bone marrow in lymphoma will be reviewed and discussed.

Scintigraphic Demonstration of Urine Extravasation Secondary to Acute Ureteral Obstruction: A Case Report and Some Considerations about Acute Ureteral Obstruction

Mon, 01 Jan 1900 00:00:00 +0000

Acute ureteral obstruction produces renal damage and complications that are proportional to the severity and length of the obstruction. Anatomic diagnosis of the obstruction may be insufficient to manage the patient. Intravenous urogram (IVU) is the method usually advised by radiologists to obtain functional information, but requires iodinated contrast agents. IVU anatomic information is superior to anatomic information obtained with renal scintigraphy, but normally the physician already has the anatomic information (unenhanced CT or ultrasound). A renal scan offers better physiologic information than the IVU, has neither adverse effects nor complications, is accurate to confirm or discard significant ureteral obstruction, and depicts obstruction complications. This paper presents a patient with spontaneous urine extravasation secondary to acute renal obstruction who is diagnosed with renal scintigraphy. The authors describe the scintigraphic signs of extraperitoneal, diffuse perinephric, urine extravasation and emphasize the role of renal scintigraphy in diagnosis and follow-up of renal colic.

Ultraviolet Fluorescence Spectra of Fingerprints

Naoki Saitoh and Norimitsu Akiba — Mon, 01 Jan 1900 00:00:00 +0000

We have studied inherent fluorescence spectra and imaging of fingerprints in the deep ultraviolet (UV) region with a nanosecond-pulsed Nd-YAG laser system that consists of a tunable laser, a cooled CCD camera, and a grating spectrometer. In this paper, we have studied UV fluorescence spectra of fingerprints under 266-nm illumination. Fluorescence spectra of fingerprints have two main peaks, around 330 nm (peak A) and 440 nm (peak B). At first, when a fingerprint has just been pressed, peak A is dominant. However, its intensity reduces as the total illumination time increases. On the other hand, peak B is weak at first. It appears after enough 266-nm illumination and its intensity increases as time elapses. After 3 h of illumination, peak A almost diminishes and peak B becomes dominant. By leaving the fingerprint under a fluorescent lamp in a room without laser illumination, peak A can be restored partly, while the intensity of peak B still increases.Time-resolved fluorescence spectra were also measured for these two peaks. The lifetime of each peak is 2.0 nsec (peak A) and 6.2 nsec (peak B) on average. Both peaks seem to consist of several components with different lifetimes. In the case of peak A, the 330-nm peak decays fast and a new component at 360 nm becomes dominant when the delay time exceeds 20 nsec. In the case of peak B, unlike peak A, no clear peak separation is observed, but the peak position seems to move from 440 to 460 nm when the delay time becomes larger.