Feasibility of photon-counting spectral CT in dental applications-a comparative qualitative analysis.

PURPOSE: The goal of this study was to demonstrate the feasibility of using photon-counting spectral CT for dental applications. This paper qualitatively analyzes the visibility of accessory canals (ACs) and metal artefacts from dental implants for cone-beam CT (CBCT), microtomography (microCT), and photon-counting spectral CT (PCSCT). MATERIALS AND METHODS: All of the teeth in this study were extracted, and eight teeth in total were scanned on a CBCT scanner, a microCT scanner and on a PCSCT scanner. Six of the teeth that were scanned have accessory canals, one has a titanium rod attached to it, and one has a gutta-percha point inside it. Qualitative analysis was done to compare the different imaging modalities. RESULTS: The subjective image analysis demonstrated similar performance in AC detection and visualisation for PCSCT and CBCT (p value >0.05). Both PCSCT and microCT performed similarly for metal artefact reduction, and both were superior to CBCT (p value <0.05). CONCLUSION: Although microCT provides detailed information about small anatomical structures, it is not suitable for in vivo use. However, the PCSCT scanner was able to detect small anatomical structures in teeth comparable to CBCT, as well as being superior in reducing metal artefacts from dental implants. This study showed that PCSCT is a promising modality for future dentistry applications.

Sequence and Observer Variability in Gadoxectic Acid-Enhanced MRI Lesion Measurements in Hepatocellular Carcinoma.

RATIONALE AND OBJECTIVES: The purpose of the study was to investigate interobserver and intersequence variability in measuring hepatocellular carcinoma on magnetic resonance imaging (MRI). METHODS AND MATERIALS: Twenty treatment-naïve lesions on Gadoxetic Acid enhanced MRI scans from 20 patients were retrospectively measured by six reviewers with different levels of experience, twice, six weeks apart, on eight different MRI sequences, in randomized order. The sequences include arterial, hepatobiliary, transitional, portal venous, T2, and diffusion weighted images. The single longest diameter (SLD) and longest diameter perpendicular to the longest overall diameter were measured on axial images and products of diameters calculated in accordance to response evaluation criteria in solid tumors v1.1 and World Health Organization response criteria respectively. Lesion-wise intraclass correlation coefficients were used to estimate measurement agreement. RESULTS: All intraclass correlation coefficients were greater than 0.95. No substantive differences between SLD and products of diameters metrics. Means (∼2.8 mm, SLD) and standard deviations (∼2 mm, SLD) were similar across sequences and observers. Similarly, pairwise comparison between observers grouped by experience showed statistically significant differences, but the effect size was minor (∼2 mm). Arterial and HPB-weighted images had similar mean dimensions (2.76 cm) while the smallest mean was in the transitional phase (2.62 cm). A lesion was not measured on 140 occasions (7%), mostly in ADC. CONCLUSION: There is high interobserver and intersequence reliability despite small differences between observers based on experience level. Our results suggest that accurate measurements can be made on arterial phase despite the possibility of indistinct margins. Lesions, however, are more likely to be missed on diffusion-related sequences.

Advancing Care for Head and Neck Cancers in a Multidisciplinary Tumour Board in the East.

Managing head and neck cancers is an excellent example of the importance of teamwork, with head and neck surgeons, clinical oncologists, radiologists, pathologists and other allied health professionals specialised in this disease site working together. The reliable imaging and dedicated pretreatment work-up entailing the comprehensive anatomical description of tumour involvement by the radiologists, the expertise of surgeons in performing en-bloc gross tumour resection, the uneventful speedy postoperative rehabilitation and recovery by the speech therapists and nutritionists, as well as the dedicated treatment planning of clinical oncologists in delivering precise preoperative or postoperative (chemo)radiotherapy to maximise the therapeutic potentials are the pillars of treatment success. A multidisciplinary tumour board involving all of these key players is essential to provide the highest level of recommendation based on evidence-based medicine and to bring patients new hopes and the best chance of cure. This review illustrates the seamless collaborative teamwork within a well-established multidisciplinary tumour board in managing one of the most intractable cancers in the East, taking enlightenment and inspiration from the West.

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.

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.

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.

Value of trainees in a radiology department. A retrospective semi-quantitative analysis.

AIM: To examine the productivity (both economic and otherwise) of trainees within a radiology department at our institution. MATERIALS AND METHODS: Productivity was measured in three ways: (1) independent workload contribution, (2) impact on on-call services, and (3) impact on day-to-day practice as perceived by consultant radiologists. Data were collected using retrospective searches on computerized radiology information system (CRIS), analysis of trainees and consultant rotas, and a questionnaire to consultants and trainees. Where possible, productivity was quantified in terms of number of programmed activities (PAs). RESULTS: The contribution of independent work by trainees in a single week was 52.75 PAs (or 1.45 PAs per trainee per week). In addition, the on-call contribution was 23.1 PAs per week (or 0.93 PAs per trainee per week). When both trainees and consultants report independently, productivity in a single list in most cases increased and can be as much as 197%. On calculating the economic impact, this amounts to significant savings of around £1.2million per year at our institution. CONCLUSION: Based upon objectively measurable areas of service provision, the employment of trainees yields considerable economic benefit. Furthermore, based upon qualitative methods we have shown that trainees contribute positively in those areas, which are much harder to quantifiably evaluate. These are benefits in addition to fundamental requirement to train future competent radiologists.

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.