Varut Vardhanabhuti

Early embryonic light detection improves survival

Classically, organization of the vertebrate circadian clock was seen as highly centralized in specific neural structures. Over recent years, this view has been transformed dramatically toward a more decentralized model with a number of distinct peripheral tissue clocks [1,2]. This is particularly true of zebrafish, where adult tissues contain autonomous circadian oscillators, which respond directly to light [3,4]. Cell lines derived from 24 hour old zebrafish embryos show the same circadian and light responsiveness as adult tissue [4,5].

Extra-pulmonary manifestations of sarcoidosis

Although, the diagnosis and evaluation of sarcoidosis has traditionally remained confined to the chest, its multi-system nature has been widely recognized. Radiological features of pulmonary sarcoidosis are well known but extra-pulmonary manifestations can produce a plethora of non-specific imaging findings that can affect subcutaneous tissue, and the neurological, cardiac, gastrointestinal, urological, liver, spleen, and skeletal systems. In the literature, there are various case reports and specific system reviews but there are few reviews that encompass all the extra-pulmonary manifestations. In this paper, we comprehensively review the imaging features of extra-pulmonary sarcoidosis with characteristic features as well as atypical presentations. In addition, we discuss the emerging role of nuclear medicine in sarcoidosis.

Flies and Fish: Birds of a Feather

The identification of specific clock‐containing structures has been a major endeavour of the circadian field for many years. This has lead to the identification of many key components of the circadian system, including the suprachiasmatic nucleus in mammals, and the eyes and pineal glands in lower vertebrates. However, the idea that these structures represent the only clocks in animals has been challenged by the discovery of peripheral pacemakers in most organs and tissues, and even a number of cell lines. In Drosophila, and vertebrates such as the zebrafish, these peripheral clocks appear to be highly autonomous, being set directly by the environmental light/dark cycle. However, a hierarchy of clocks may still exist in mammals. In this review, we examine some of the current views regarding peripheral clocks, their organization and how they are entrained.

Comprehensive Musculoskeletal Sonographic Evaluation of the Hand and Wrist

Sonography is widely used for evaluation of hand and wrist lesions. The easy accessibility, cost‐effectiveness, and good diagnostic accuracy of sonography coupled with the numerous benefits of real‐time imaging make it desirable. The aim of this article is to describe the typical sonographic appearances of lesions in the hand and wrist that are encountered frequently in routine clinical practice, such as inflammatory arthropathies, tumors, traumatic injuries, foreign bodies, and nerve entrapment syndromes. Relevant anatomy, scanning methods, and recent developments in musculoskeletal sonography are also discussed.

Imaging features of therapeutic drug-induced musculoskeletal abnormalities.

Increasing use of a wide variety of therapeutic drugs with known musculoskeletal side-effect profiles necessitates a rigorous understanding and approach when evaluating imaging features suggestive of drug-induced musculoskeletal abnormalities. The etiology of such abnormalities is diverse, and the clinical and imaging manifestations may be nonspecific. The recognition of adverse effects depends, first, on the physicians vigilant review of clinical information for relevant drug history and indicative signs, and second, on the radiologists ability to detect musculoskeletal changes consistent with known potential effects of specific drugs. Musculoskeletal abnormalities induced by therapeutic drugs may be broadly categorized as embryopathic, juvenile, or postmaturation. Embryopathic skeletal abnormalities result from the teratogenic effects of drugs administered to pregnant women (eg, thalidomide, anticonvulsants). Other therapeutic agents characteristically lead to abnormalities during postnatal skeletal maturation (eg, high-dose vitamins or prostaglandin) either because they are used exclusively in children or because they have idiosyncratic effects on immature musculoskeletal structures. Many drugs (eg, statins) may have musculoskeletal side effects that, although independent of the stage of skeletal maturation, are most often seen in adults or elderly people because they are commonly prescribed for people in these age groups. Drug-induced musculoskeletal abnormalities may be further characterized according to the predominant skeletal manifestations as osteomalacic, proliferative, or osteoporotic and according to the involvement of soft tissues as musculotendinous or chondral.

Model-Based Iterative Reconstruction in Low-Dose CT Colonography—Feasibility Study in 65 Patients for Symptomatic Investigation

RATIONALE AND OBJECTIVES To compare image quality on computed tomographic colonography (CTC) acquired at standard dose (STD) and low dose (LD) using filtered-back projection, adaptive statistical iterative reconstruction, and model-based iterative reconstruction (MBIR) techniques. MATERIALS AND METHODS A total of 65 symptomatic patients were prospectively enrolled for the study and underwent STD and LD CTC with filtered-back projection, adaptive statistical iterative reconstruction, and MBIR to allow direct per-patient comparison. Objective image noise, subjective image analyses, and polyp detection were assessed. RESULTS Objective image noise analysis demonstrates significant noise reduction using MBIR technique (P < .05) despite being acquired at lower doses. Subjective image analyses were superior for LD MBIR in all parameters except visibility of extracolonic lesions (two-dimensional) and visibility of colonic wall (three-dimensional) where there were no significant differences. There was no significant difference in polyp detection rates (P > .05). Doses: LD (dose-length product, 257.7), STD (dose-length product, 483.6). CONCLUSIONS LD MBIR CTC objectively shows improved image noise using parameters in our study. Subjectively, image quality is maintained. Polyp detection shows no significant difference but because of small numbers needs further validation. Average dose reduction of 47% can be achieved. This study confirms feasibility of using MBIR in this context of CTC in symptomatic population.

The varied sonographic appearances of focal fatty liver disease: Review and diagnostic algorithm

Focal fat infiltration and focal fat sparing of the liver are less common than diffuse fat infiltration but present a greater diagnostic conundrum. Although typical features of these conditions are well described, there is a wide variety of different appearances. These atypical patterns present significant difficulty in differentiation from other pathological processes and often require additional investigation. We present an innovative diagnostic algorithm and illustrate its effectiveness in diagnosing focal fatty liver disease with typical and atypical examples.

The role of multidetector computed tomography coronary angiography in imaging complications post-cardiac surgery

There have been numerous advances in the field of cardiac imaging. The advent of multidetector computed tomography coronary angiography (MDCT-CA) and in particular electrocardiographic (ECG)-gated acquisition has revolutionized the investigation of the complete spectrum of complications of common cardiothoracic surgical procedures. Generic complications, such as mediastinitis, pericardial effusion, sternal osteomyelitis, and mediastinal fibrosis, are discussed with illustrative examples of multiplanar and volume-rendered three-dimensional reconstructions. Graft-related complications of both coronary artery bypass grafts and aortic root grafts are reviewed. The role of MDCT-CA in the investigation of prosthetic valve endocarditis and root abscesses is outlined. We present a complete illustration of the detailed images that are obtained when investigating a full range of graft-related complications from both aortic and coronary surgery using ECG-gated MDCT-CA. MDCT-CA has the potential to become established as the optimal technique with which to image a multitude of complications post-cardiac surgery.

Factors that affect PERCIST-defined test-retest comparability: an exploration of feasibility in routine clinical practice

Purpose The aim of this study was to evaluate the factors affecting the comparability of 18F-FDG PET/CT scans using the PERSIST criteria for treatment response evaluation in a clinical PET/CT unit. Patients and Methods Patients diagnosed with esophageal cancer were assessed for treatment response by comparing 2 18F-FDG PET/CT scans, at baseline (PET 1) and 1 month after the end of induction chemoradiation (PET 2). According to the PERCIST recommendations, patients with mean SUV normalized by the lean body mass within reference volume of interest that changed less than 0.3 unit and less than 20% were deemed as comparable. Absolute differences of body weight, blood glucose level, activity of 18F-FDG, and uptake time between the 2 scans were computed. Binary logistic regression was used to identify the predictive factors, and receiver operating characteristic curves were used for thresholds. P < 0.05 was considered statistically significant. Results Sixty-nine subjects were identified. The mean (SD) values at PET 0 and PET 2 were 5.9 (1.04) mmol/L and 6.2 (1.06) mmol/L (P = 0.013), 54.6 (10.0 kg) and 53.3 (10.3 kg) (P = 0.013), 7.7 (1.3 mCi) and 7.6 (1.5 mCi) (P = 0.349), as well as 74.2 (12.4) minutes and 73.0 (12.3) minutes (P = 0.539), for blood glucose level, body weight, injected activity, and uptake time, respectively. Seventeen (24.6%) failed to match the PERCIST-defined comparability criteria. Case-based discrepancies (mean [SD]) were 0.76 (0.62) mmol/L, 3.4 (2.9) kg, 0.8 (0.7) mCi, and 11.7 (9.8) minutes for blood glucose, body weight, injected activity, and uptake time, respectively, of which only uptake time significantly affected comparability (P = 0.046; odds ratio, 1.06; 95% confidence interval, 1.00–1.12), with a limit of 2.2-minute discrepancy identified as the requirement for 100% comparability. Conclusions Uptake time had the strongest effect on PERCIST-defined comparability. Therefore, for response assessment scans, reference to initial scans for determination of optimal uptake time is recommended.

Sarcoidosis—The Greatest Mimic

Little is known regarding the exact pathogenesis of sarcoidosis, but it is widely recognized that it affects multiple organs. The presentation and imaging features can be nonspecific, and this is the reason why it is a great mimic of other diseases. Diagnosis of sarcoidosis is often prompted initially by clinical suspicion. Imaging plays a crucial role in both detection and monitoring of disease process. This review is a case-based systemic approach looking at various systemic manifestation of the disease presenting real clinical encounters using various imaging modalities.