Four multidetector-row helical CT: image quality and volume coverage speed

Diagnostic utility of multidetector CT scan in penetrating diaphragmatic injuries: A systematic review and meta-analysis

Penetrating diaphragmatic injuries pose diagnostic and management challenges. Computed tomography (CT) scans are valuable for stable patients, but concern exists for missed injuries and complications in nonoperatively managed cases. The objective of this study was to explore the diagnostic utility of multidetector CT scan (MDCT) in identifying diaphragmatic injuries resulting from penetrating trauma. A systematic review and meta-analysis were conducted, following established guidelines, by searching PubMed, Scopus, Web of Science, and Embase databases up to July 6, 2023. Eligible studies reporting MDCT's diagnostic accuracy in detecting penetrating diaphragmatic injuries were included. Relevant data elements were extracted and analyzed using STATA software. The study included 9 articles comprising 294 patients with confirmed penetrating diaphragmatic injuries through surgical procedures. MDCT's diagnostic performance revealed a pooled sensitivity of 74% (95% CI: 56%-87%) and a pooled specificity of 92% (95% CI: 79%-97%) (Fig. two), with significant heterogeneity in both sensitivity and specificity across the studies. The Fagan plot demonstrated that higher pre-test probabilities correlated with higher positive post-test probabilities for penetrating diaphragmatic injury diagnosis using MDCT, but even with negative results, there remained a small chance of having the injury, especially in cases with higher pre-test probabilities. This study highlights MDCT's effectiveness in detecting diaphragmatic injury from penetrating trauma, with moderate to high diagnostic accuracy. However, larger sample sizes, multicenter collaborations, and prospective designs are needed to address observed heterogeneity, enhancing understanding and consistency in MDCT's diagnostic capabilities in this context.

Progress of CT aortic angiography combined with coronary artery in the evaluation of acute aortic syndrome

Acute aortic syndrome (AAS) is a group of cardiovascular diseases that seriously threaten human life and health. AAS patients are often complicated with coronary artery disease and other related diseases, which require rapid and clear clinical diagnosis to avoid serious adverse events. In recent years, with the progress of science and technology, a variety of computer tomography (CT) angiography techniques have been applied in the clinic, and the diagnosis rate of AAS with coronary heart disease (CAD) has greatly increased. At the same time, the development of surgical technology and endovascular repair technology has significantly reduced the mortality and complication rate of AAS surgery. In the clinical diagnosis of AAS and related diseases, CT aortic angiography (CTA) combined with coronary CTA is increasingly applied to identify related diseases. Here, the current research progress on the technique of aortic CTA combined with coronary CTA is reviewed.

Photon-Counting Detectors in Computed Tomography: A Review

Photon-counting computed tomography (CT) is a new technique that has the potential to revolutionize clinical CT and is predicted to be the next significant advancement. In recent years, tremendous research has been conducted to demonstrate the developments in hardware assembly and its working principles. The articles in this review were obtained by conducting a search of the MEDLINE database. Photon-counting detectors (PCDs) provide excellent quality diagnostic images with high spatial resolution, reduced noise, artifacts, increased contrast-to-noise ratio, and multienergy data acquisition as compared with conventionally used energy-integrating detector (EID). The search covered articles published between 2011 and 2021. The title and abstract of each article were reviewed as determined by the search strategy. From these, eligible studies and articles that provided the working and clinical application of PCDs were selected. This article aims to provide a systematic review of the basic working principles of PCDs, emphasize the uses and clinical applications of PCDs, and compare it to EIDs. It provides a nonmathematical explanation and understanding of photon-counting CT systems for radiologists as well as clinicians.

Bridging nano- and microscale X-ray tomography for battery research by leveraging artificial intelligence

X-ray computed tomography (CT) is a non-destructive imaging technique in which contrast originates from the materials' absorption coefficient. The recent development of laboratory nanoscale CT (nano-CT) systems has pushed the spatial resolution for battery material imaging to voxel sizes of 50 nm, a limit previously achievable only with synchrotron facilities. Given the non-destructive nature of CT, in situ and operando studies have emerged as powerful methods to quantify morphological parameters, such as tortuosity factor, porosity, surface area and volume expansion, during battery operation or cycling. Combined with artificial intelligence and machine learning analysis techniques, nano-CT has enabled the development of predictive models to analyse the impact of the electrode microstructure on cell performances or the influence of material heterogeneities on electrochemical responses. In this Review, we discuss the role of X-ray CT and nano-CT experimentation in the battery field, discuss the incorporation of artificial intelligence and machine learning analyses and provide a perspective on how the combination of multiscale CT imaging techniques can expand the development of predictive multiscale battery behavioural models.

A Fast Image Guide Registration Supported by Single Direction Projected CBCT

Image registration is an important research topic in medical image-guided therapy, which is dedicated to registering the high-dose imaging sequences with low-dose/faster means. Registering computer tomography (CT) scanning sequences with cone beam computer tomography (CBCT) scanning sequences is a typical application and has been widely used in CBCT-guided radiotherapy. The main problem is the difference in image clarity of these two image sequences. To solve this problem, for the single projection image sequence matching tasks encountered in medical practice, a novel local quality based curved section encoding strategy is proposed in this paper, which is called the high-quality curved section (HQCS). As an optimized cross-section regularly encoded along the sequence of image, this curved section could be used in order to solve the matching problem. Referencing the independent ground truth provided by medical image physicians, with an experiment combined with the four most widely used indicators used on image registration, matching performance of HQCS on CT/CBCT datasets was tested with varying clarity. Experimental results show that the proposed HQCS can register the CT/CBCT effectively and outperforms the commonly used methods. Specifically, the proposed HQCS has low time complexity and higher scalability, which indicates that the application enhanced the task of diagnosis.

Use of cone-beam computed tomography for advanced imaging of the equine patient

Access to volumetric imaging modalities, such as magnetic resonance imaging (MRI) and computed tomography (CT), has increased over the past decade and has revolutionised the way clinicians evaluate equine anatomy. More recent advancements have resulted in the development of multiple commercially available cone-beam CT (CBCT) scanners for equine use. CBCT scanners modify the traditional fan-shaped beam of ionising radiation into a three-dimensional pyramidal- or cone-shaped beam of radiation. This modification enables the scanner to acquire sufficient data to create diagnostic images of a region of interest after a single rotation of the gantry. The rapid acquisition of data and divergent X-ray beam causes some artifacts to be more prominent on CBCT images-as well as the unique cone-beam artifact-resulting in decreased contrast resolution. While the use of CT for evaluation of the equine musculoskeletal anatomy is not new, there is a paucity of literature and scientific studies on the capabilities of CBCT for equine imaging. CBCT units do not require a specialised table for imaging and in some cases are portable for imaging in the standing or anaesthetised patient. This review article summarises the basic physics of CT technology, including how CBCT imaging differs, and provides objective information about the strengths and limitations of this modality. Finally, potential future applications and techniques for imaging with CT which will need to be explored in order to fully consider the capabilities of CT imaging in the horse are discussed.

Ultra-low-dose CT-guided lung biopsy in clinic: radiation dose, accuracy, image quality, and complication rate

BACKGROUND

Computed tomography (CT)-guided percutaneous lung biopsy is usually performed by helical scanning. However, there are no studies on radiation dose, diagnostic accuracy, image quality, and complications based on axial scan mode.

PURPOSE

To determine radiation dose, accuracy, image quality, and complication rate following an ultra-low-dose (ULD) protocol for CT-guided lung biopsy in clinic.

MATERIAL AND METHODS

A total of 105 patients were enrolled to receive CT-guided lung biopsy. The use of an ULD protocol (axial scan) for CT-guided biopsy was initiated. Patients were randomly assigned to axial mode (Group A) and conventional helical mode (Group B) CT groups. 64-slice CT was performed for CT-guided pulmonary biopsy with an 18-G coaxial cutting biopsy needle. The radiation dose, accuracy, image quality, and complication rate were measured.

RESULTS

Ninety-seven patients were selected for the final phase of the study. There was no significant difference between the two groups for pulmonary nodule characteristics (P > 0.05). The mean effective dose in group A (0.077 ± 0.010 mSv) was significantly reduced relative to group B (0.653 ± 0.177 mSv, P < 0.001). There was no significant difference in accuracy, image quality, and complication rate (P > 0.050) between the two modes.

CONCLUSION

An ULD protocol for CT-guided lung nodule biopsy yields a reduction in the radiation dose without significant change in the accuracy, image quality, and complication rate relative to the conventional helical mode scan.

The role of imaging in head and neck cancer: An overview of different imaging modalities in primary diagnosis and staging of the disease

Radiology has an essential role in diagnosis, staging, and management in all subspecialties related to oncology. It has a broad utility from its use as an initial screening tool for cancer detection, followed by staging and surveillance of disease as well as the delivery of appropriate treatment regimens. In order to plan a treatment, the use of different modalities of radiological imaging are a key factor for pre-treatment planning and staging of the extent of disease in accordance with tumor-node-metastasis (TNM) system for highly conformal treatments, such as brachytherapy (BT). In this work, we present an overview of main modalities of imaging and principles of their application especially in head and neck cancer, with its diagnosis, treatment, follow-up with post-treatment changes, and overall management.

Axial or Helical? Considerations for wide collimation CT scanners capable of volumetric imaging in both modes

PURPOSE

To determine whether axial or helical mode is more appropriate for a 16 cm collimation CT scanner capable of step-and-shoot volumetric axial coverage, in terms of radiation dose, image quality, and scan duration.

METHODS

All scans were performed with a Revolution CT (GE Healthcare) operating at 120 kV and 100 mAs. Using calibrated optically stimulated luminescence detectors, radiation dose along the axial scan profile was evaluated at the isocenter, including the overlap region between two axial sections. This overlap region measures 3 cm in the z-axis at the isocenter and is required to obtain sufficient projection data from the relatively large cone-beam angles. Using an image quality phantom (Gammex Model 464), spatial resolution, CT number uniformity, image noise, and low contrast detectability (LCD) were evaluated under five different conditions: in the middle of a helical acquisition, in the middle of a 16 cm axial section, at both ends of an axial section and in the overlap region between two axial sections. Scan durations and dose length products (DLP) were recorded for prescribed scan lengths of 2.5-100 cm.

RESULTS

The overlap region between two axial sections received a dose 83% higher than the single-exposure region at the isocenter. Within a single axial section, the dose at the anode end was 37% less than at the cathode end due to the anode heel effect. Image noise ranged from a low of 13 HU for the cathode end of an axial section up to 14.7 HU for the anode end (P < 0.001). The LCD was at lower at the anode end of the axial section compared to both the cathode end (P < 0.05) and the overlap location (P < 0.02). The spatial resolution and CT number uniformity were consistent among all conditions. Scan durations were shorter (0.28 s) for the axial mode compared to the helical mode at scan lengths ≤ 16 cm, and longer at scan lengths ≥ 16 cm where more than one table position was required, up to a difference of 13.9 s for a the 100 cm scan length (3.8 s for helical compared to 17.6 s for axial). DLPs were consistent between scan modes; slightly lower in axial mode at shorter scan lengths due to helical overranging, and slightly higher in axial mode at longer scan lengths due to the axial overlap regions.

CONCLUSIONS

To ensure the most consistent radiation dose and image quality along the scan length, we recommend helical mode for scans longer than the 16 cm coverage of a single axial section. For scan lengths ≤ 16 cm, axial scanning is the most practical option, with a shorter scan duration and higher dose efficiency.

Diagnostic accuracy of contemporary multidetector computed tomography (MDCT) for the detection of lumbar disc herniation

OBJECTIVES

To evaluate the diagnostic accuracy of multidetector CT (MDCT) for detection of lumbar disc herniation with MRI as standard of reference.

METHODS

Patients with low back pain underwent indicated MDCT (128-row MDCT, helical pitch), 60 patients with iterative reconstruction (IR) and 67 patients with filtered back projection (FBP). Lumbar spine MRI (1.5 T) was performed within 1 month. Signal-to-noise ratios (SNR) of cerebrospinal fluid (CSF), annulus fibrosus (AF) and the spinal cord (SC) were determined for all modalities. Two readers independently rated image quality (IQ), diagnostic confidence and accuracy in the diagnosis of lumbar disc herniation using MRI as standard of reference. Inter-reader correlation was assessed with weighted κ.

RESULTS

Sensitivity, specificity, precision and accuracy of MDCT for disc protrusion were 98.8%, 96.5%, 97.1%, 97.8% (disc level), 97.7%, 92.9%, 98.6%, 96.9% (patient level). SNR of IR was significantly higher than FBP. IQ was significantly better in IR owing to visually reduced noise and improved delineation of the discs. κ (>0.90) was excellent for both algorithms.

CONCLUSION

MDCT of the lumbar spine yields high diagnostic accuracy for detection of lumbar disc herniation. IR improves image quality so that the provided diagnostic accuracy is principally equivalent to MRI.

KEY POINTS

• MDCT is an accurate alternative to MRI in disc herniation diagnosis. • By IR enhanced image quality improves MDCT diagnostic confidence similar to MRI. • Advances in CT technology contribute to improved diagnostic performance in lumbar spine imaging.

Scattered image artifacts from cone beam computed tomography and its clinical potential in bone mineral density estimation

Background

Image artifacts affect the quality of medical images and may obscure anatomic structure and pathology. Numerous methods for suppression and correction of scattered image artifacts have been suggested in the past three decades. In this paper, we assessed the feasibility of use of information on scattered artifacts for estimation of bone mineral density (BMD) without dual-energy X-ray absorptiometry (DXA) or quantitative computed tomographic imaging (QCT).

Methods

To investigate the relationship between scattered image artifacts and BMD, we first used a forearm phantom and cone-beam computed tomography. In the phantom, we considered two regions of interest—bone-equivalent solid material containing 50 mg HA per cm⁻³ and water—to represent low- and high-density trabecular bone, respectively. We compared the scattered image artifacts in the high-density material with those in the low-density material. The technique was then applied to osteoporosis patients and healthy subjects to assess its feasibility for BMD estimation.

Results

The high-density material produced a greater number of scattered image artifacts than the low-density material. Moreover, the radius and ulna of healthy subjects produced a greater number of scattered image artifacts than those from osteoporosis patients.

Conclusions

Although other parameters, such as bone thickness and X-ray incidence, should be considered, our technique facilitated BMD estimation directly without DXA or QCT. We believe that BMD estimation based on assessment of scattered image artifacts may benefit the prevention, early treatment and management of osteoporosis.

Optimization of scan timing for aortic computed tomographic angiography using the test bolus injection technique

BACKGROUND

With fast computed tomography (CT), it is possible for the scanning to outpace the contrast medium bolus during aortic CT angiography (CTA).

PURPOSE

To evaluate the effectiveness of a new method for reducing the risk of outpacing in which the scan start timing (ST) and speed can be estimated from the peak enhancement time measured at the femoral artery using a single test-bolus injection (femoral artery test injection method [FTI method]).

MATERIAL AND METHODS

In 30 cases of aortic CTA, we measured the time to peak enhancement at the femoral artery (TPF) and the ascending aorta (TPA) with test-bolus injection performed twice in each examination. From the resultant linear relationship between TPF and transit time (TT = TPF - TPA), we developed a method for determining the ST and TT from TPF. One hundred patients were assigned to two groups: FTI and bolus tracking (BT), each with 50 patients. CT values were measured in main vessels (ascending aorta, descending aorta, femoral artery). The CT values of the vessels and the rate of cases with more than 300 HU (good cases) were compared between the two groups.

RESULTS

The enhancement in the FTI method was significantly higher than that of the BT method (average CT values: FTI, 388.3 ± 52.4; BT, 281.2 ± 59.1; P < 0.001). The rates of good cases for FTI and BT were 86.0% and 46.0%, respectively.

CONCLUSION

The FTI method was very effective in reducing the risk of outpacing of the contrast medium transit in aortic CTA without the need for an additional contrast medium dose.

Fundamentals of cone beam computed tomography for a prosthodontist

Cone beam computed tomography (CBCT, also referred to as C-arm computed tomography [CT], cone beam volume CT, or flat panel CT) is a medical imaging technique of X-ray CT where the X-rays are divergent, forming a cone.[1] CBCT systems have been designed for imaging hard tissues of the maxillofacial region. CBCT is capable of providing sub-millimeter resolution in images of high diagnostic quality, with short scanning times (10–70 s) and radiation dosages reportedly up to 15–100 times lower than those of conventional CT scans. Increasing availability of this technology provides the dental clinician with an imaging modality capable of providing a three-dimensional representation of the maxillofacial skeleton with minimal distortion. The aim of this article is to sensitize the Prosthodontist to CBCT technology, provide an overview of currently available maxillofacial CBCT systems and review the specific application of various CBCT display modes to clinical Prosthodontic practice. A MEDLINE search for relevant articles in this specific area of interest was conducted. The selected articles were critically reviewed and the data acquired were systematically compiled.

Multi-detector computed tomography imaging of large airway pathology: A pictorial review

The tracheobronchial tree is a musculo-cartilagenous framework which acts as a conduit to aerate the lungs and consequently the entire body. A large spectrum of pathological conditions can involve the trachea and bronchial airways. These may be congenital anomalies, infections, post-intubation airway injuries, foreign body aspiration or neoplasms involving the airway. Appropriate management of airway disease requires an early and accurate diagnosis. In this pictorial essay review, we will comprehensively describe the various airway pathologies and their imaging findings by multi-detector computed tomography.

Imaging Patterns in MRI in Recent Bone Injuries Following Negative or Inconclusive Plain Radiographs

BACKGROUND

Few bony injuries and most soft tissue injuries cannot be detected on plain radiography. Magnetic resonance imaging (MRI) can detect such occult bony injuries due to signal changes in bone marrow. In addition to excluding serious bony injuries, it can also identify tendon, ligament, cartilage and other soft tissue injuries and thus help in localizing the cause of morbidity.

AIMS AND OBJECTIVES

To determine the MRI imaging patterns in recent bone injuries (less than 4 weeks) following negative or inconclusive plain radiographs. To determine the role of MRI in recent fractures.

RESULTS

Out of the 75 individuals with history of recent injury of less than 4 weeks duration, fracture line was demonstrated in 16 patients (21%) who had no obvious evidence of bone injury on plain radiographs. Bone contusion or bruising of the bone was demonstrated in 39 (52%) patients. This was the commonest abnormality detected in MRI. The remaining 20 patients did not show any obvious injury to the bone on MR imaging however, soft tissue injury could be demonstrated in 12 (16%) patients which show that the extent of soft tissue injury was relatively well demonstrated by MR imaging. The present study showed that occult injuries commonly occur at the Knee followed by Ankle, Wrist, Foot, Elbow, Leg, Hands, Hips & Spine.

CONCLUSION

The study showed that MR is efficient in the detection of occult bone injuries which are missed on radiography. Compared to radiographs, MRI clearly depicted the extent of injuries and associated soft tissue involvement. MRI demonstrates both acute and chronic injuries and also differentiates both, whereas radiography has poor sensitivity for acute injuries. Also, the soft tissue injuries like tendionous and ligamentous injuries cannot be identified on radiographs.

Evaluation of diaphragm in penetrating left thoracoabdominal stab injuries: The role of multislice computed tomography

INTRODUCTION

Penetrating left thoracoabdominal stab injuries are accompanied by diaphragmatic injury in 25-30% of cases, about 30% of which later develop into diaphragmatic hernia. This study aimed to determine the role of multislice computed tomography in the evaluation of left diaphragm in patients with penetrating left thoracoabdominal stab wounds.

MATERIALS AND METHODS

This study reviewed penetrating left thoracoabdominal stab injuries managed in our clinic between April 2009 and September 2014. The thoracoabdominal region was defined as the region between the sternum, fourth intercostal space, and arcus costa anteriorly and the vertebra, lower tip of scapula, and the curve of the last rib posteriorly. Unstable cases and cases with signs of peritonitis were operated with laparotomy; the remaining patients were closely monitored. Forty-eight hours later, a diagnostic laparoscopy was applied to evaluate the left hemidiaphragma in asymptomatic patients who did not need laparotomy. The preoperatively obtained multislice thoracoabdominal computed tomography images were retrospectively examined for the presence of left diaphragm injury. Then, operative and tomographic findings were compared.

RESULTS

This study included a total of 43 patients, 39 (91%) males and 4 (9%) females of mean age 30 years (range 15-61 years). Thirty patients had normal tomography results, whereas 13 had left diaphragmatic injuries. An injury to the left diaphragm was detected during the operation in 9 (1 in laparotomy and 8 in diagnostic laparoscopy) of 13 patients with positive tomography for left diaphragmatic injury and 2 (in diagnostic laparoscopy) of 30 patients with negative tomography. Multislice tomography had a sensitivity of 82% (95% CI: 48-98%), a specificity of 88% (71-96%), a positive predictive value of 69% (39-91%), and a negative predictive value of 93% (78-99%) for detection of diaphragmatic injury in penetrating left thoracoabdominal stab injury.

CONCLUSIONS

Although diagnostic laparoscopy is the gold standard for diaphragmatic examination in patients with penetrating left thoracoabdominal stab wounds, multislice computed tomography is also valuable for detecting diaphragmatic injury.

Novel imaging approaches in adult asthma and their clinical potential

Currently, imaging in asthma is confined to chest radiography and CT. The emergence of new imaging techniques and tremendous improvement of existing imaging methods, primarily due to technological advancement, has completely changed its research and clinical prospects. In research, imaging in asthma is now being employed to provide quantitative assessment of morphology, function and pathogenic processes at the molecular level. The unique ability of imaging for non-invasive, repeated, quantitative, and in vivo assessment of structure and function in asthma could lead to identification of 'imaging biomarkers' with potential as outcome measures in future clinical trials. Emerging imaging techniques and their utility in the research and clinical setting is discussed in this review.

Energy dispersive CdTe and CdZnTe detectors for spectral clinical CT and NDT applications

We are developing room temperature compound semiconductor detectors for applications in energy-resolved high-flux single x-ray photon-counting spectral computed tomography (CT), including functional imaging with nanoparticle contrast agents for medical applications and non destructive testing (NDT) for security applications. Energy-resolved photon-counting can provide reduced patient dose through optimal energy weighting for a particular imaging task in CT, functional contrast enhancement through spectroscopic imaging of metal nanoparticles in CT, and compositional analysis through multiple basis function material decomposition in CT and NDT. These applications produce high input count rates from an x-ray generator delivered to the detector. Therefore, in order to achieve energy-resolved single photon counting in these applications, a high output count rate (OCR) for an energy-dispersive detector must be achieved at the required spatial resolution and across the required dynamic range for the application. The required performance in terms of the OCR, spatial resolution, and dynamic range must be obtained with sufficient field of view (FOV) for the application thus requiring the tiling of pixel arrays and scanning techniques. Room temperature cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) compound semiconductors, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel provided the sensors are designed for rapid signal formation across the x-ray energy ranges of the application at the required energy and spatial resolutions, and at a sufficiently high detective quantum efficiency (DQE). We have developed high-flux energy-resolved photon-counting x-ray imaging array sensors using pixellated CdTe and CdZnTe semiconductors optimized for clinical CT and security NDT. We have also fabricated high-flux ASICs with a two dimensional (2D) array of inputs for readout from the sensors. The sensors are guard ring free and have a 2D array of pixels and can be tiled in 2D while preserving pixel pitch. The 2D ASICs have four energy bins with a linear energy response across sufficient dynamic range for clinical CT and some NDT applications. The ASICs can also be tiled in 2D and are designed to fit within the active area of the sensors. We have measured several important performance parameters including; the output count rate (OCR) in excess of 20 million counts per second per square mm with a minimum loss of counts due to pulse pile-up, an energy resolution of 7 keV full width at half maximum (FWHM) across the entire dynamic range, and a noise floor about 20keV. This is achieved by directly interconnecting the ASIC inputs to the pixels of the CdZnTe sensors incurring very little input capacitance to the ASICs. We present measurements of the performance of the CdTe and CdZnTe sensors including the OCR, FWHM energy resolution, noise floor, as well as the temporal stability and uniformity under the rapidly varying high flux expected in CT and NDT applications.

Computed tomography: revolutionizing the practice of medicine for 40 years

Computed tomography (CT) has had a profound effect on the practice of medicine. Both the spectrum of clinical applications and the role that CT has played in enhancing the depth of our understanding of disease have been profound. Although almost 90 000 articles on CT have been published in peer-reviewed journals over the past 40 years, fewer than 5% of these have been published in Radiology. Nevertheless, these almost 4000 articles have provided a basis for many important medical advances. By enabling a deepened understanding of anatomy, physiology, and pathology, CT has facilitated key advances in the detection and management of disease. This article celebrates this breadth of scientific discovery and development by examining the impact that CT has had on the diagnosis, characterization, and management of a sampling of major health challenges, including stroke, vascular diseases, cancer, trauma, acute abdominal pain, and diffuse lung diseases, as related to key technical advances in CT and manifested in Radiology.

Quantitative assessment by measurement and modeling of mobile target elongation in cone-beam computed tomographic imaging

The purpose of this study was to assess quantitatively elongation of mobile targets in cone‐beam CT (CBCT) imaging by measurement and modeling. A mathematical model was derived that predicts the measured lengths of mobile targets and its dependence on target size and motion patterns in CBCT imaging. Three tissue‐equivalent targets of differing sizes were inserted in an artificial thorax phantom to simulate lung lesions. Respiratory motion was mimicked with a mobile phantom that moves in one‐dimension along the superior‐inferior direction at a respiration frequency of 0.24 Hz for eight different amplitudes in the range 0‐40 mm. A mathematical model was derived to quantify the variations in target lengths and its dependence on phantom motion parameters in CBCT. Predictions of the model were verified by measurement of the lengths of mobile targets in CBCT images. The model predicts that target lengths increased linearly with increase in speed and amplitude of phantom motion in CBCT. The measured lengths of mobile targets imaged with CBCT agreed with the calculated lengths within half‐slice thickness spatial resolution. The maximal length of a mobile target was independent of the frequency and phase of motion. Elongation of mobile targets was similar in halffan and full‐fan CBCT for similar motion patterns, as long as the targets remained within the imaging view. Mobile targets elongated linearly with phantom speed and motion amplitude in CBCT imaging. The model introduced in this work assessed quantitatively the variation in target lengths induced by motion, which may be a useful tool to consider elongations of mobile targets in CBCT applications in diagnostic imaging and radiotherapy.

PACS number: 87.57.qp

MDCT of Small Bowel Obstruction: How Reliable Are Oblique Reformatted Images in Localizing Point of Transition?

The goal of this study is to prospectively assess the additional value of oblique reformatted images for localizing POT, having surgery as a reference standard. Materials and Methods. 102 consecutive patients with suspected small bowel obstruction (SBO) underwent 64-slice multidetector row CT (MDCT) using surgical findings as reference standard. Two independent GI radiologists reviewed the CT scans to localize the exact POT by evaluating axial images (data set A) followed by axial, coronal, and oblique MPR images. CT findings were compared to surgical findings in terms of diagnostic performance. McNemar's test was used to detect any statistical difference in POT evaluation between datasets A and B. Kappa statistics were applied for measuring agreement between two readers. Results. There was a diagnostic improvement of 9.9% in the case of the less experienced radiologist in localizing POT by using oblique reformatted images. The more experienced radiologist showed diagnostic improvement by 12.9%.

The evolution of cephalometric diagnosis in orthodontics

INTRODUCTION

Although the development of CT have represented a landmark in diagnostic imaging, its use in Dentistry turned out very discretely over the years. With the appearance of programs for analysis of three-dimensional images, specific for Orthodontics and Orthognathic surgery, a new reality is being built.

OBJECTIVE

The authors of this study aim to inform the orthodontic society of fundamentals about digital cephalometric radiographic image and computed tomography, discussing about: Field of view (FOV), radiation doses, demands for the use in Orthodontics and radiographic simulations.

Fatal cranial injury in an individual from Messina (Sicily) during the times of the Roman Empire

Forensic and archaeological examinations of human skeletons can provide us with evidence of violence. In this paper, we present the patterns of two cranial lesions found on an adult male (T173) buried in a grave in the necropolis 'Isolato 96', Messina, Sicily, dating back to the Roman Empire (1st century BC - 1st century AD). The skull reveals two perimortem traumatic lesions, one produced by a sharp object on the right parietal bone and the other one on the left parietal bone, presumably the result of a fall. The interpretation of fracture patterns found in this cranium are an illustration of how forensic approaches can be applied with great benefit to archaeological specimens.

Multislice CT: technical principles and future trends

Multislice scanning has substantially improved the performance of CT scanners, and thus the relation between scan duration, available scan length, and spatial resolution along the patient axis (z-axis). Near-isotropic imaging of whole organ systems is already possible with 4-slice scanners, but only with 8- to 16-slice scanners can the scan duration be shortened as well. Reconstructing overlapping thin-section data ("secondary raw data set") provides the basis for image reconstruction in any desired plane. By using thick multiplanar reformation (MPR) techniques, image quality can be improved while keeping patient dose low. Using unfavorable scanning parameters, exposure dose can be substantially increased compared with single-slice scanning, but thick MPR and individual-dose modulation techniques can provide the basis for dose reduction. Low-kVp scanning, in particular, is useful in children and slim adults and is an excellent technique to improve image contrast in CT angiographic studies. Short spiral scans should be avoided with multislice CT since overranging (extra rotations at the beginning and end of the scan, used for data interpolation) can substantially increase patient dose. Future trends include the introduction of thinner detector rows, wider detector arrays, faster tube rotation, and area detectors than can also be used for fluoroscopy. Noise-reduction techniques and individual dose modulation will gain importance with higher isotropic resolution. Functional and perfusion imaging, as well as advanced image processing and computer-aided diagnosis programs, will add to the possibilities of the next generation of multislice CT scanners.

Multiplanar and two-dimensional imaging of central airway stenting with multidetector computed tomography

Background

Multidetector computed tomography (MDCT) provides guidance for primary screening of the central airways. The aim of our study was assessing the contribution of multidetector computed tomography- two dimensional reconstruction in the management of patients with tracheobronchial stenosis prior to the procedure and during a short follow up period of 3 months after the endobronchial treatment.

Methods

This is a retrospective study with data collected from an electronic database and from the medical records. Patients evaluated with MDCT and who had undergone a stenting procedure were included. A Philips RSGDT 07605 model MDCT was used, and slice thickness, 3 mm; overlap, 1.5 mm; matrix, 512x512; mass, 90 and kV, 120 were evaluated. The diameters of the airways 10 mm proximal and 10 mm distal to the obstruction were measured and the stent diameter (D) was determined from the average between D upper and D lower.

Results

Fifty-six patients, 14 (25%) women and 42 (75%) men, mean age 55.3 ± 13.2 years (range: 16-79 years), were assessed by MDCT and then treated with placement of an endobronchial stent. A computed tomography review was made with 6 detector Philips RSGDT 07605 multidetector computed tomography device. Endobronchial therapy was provided for the patients with endoluminal lesions. Stents were placed into the area of stenosis in patients with external compression after dilatation and debulking procedures had been carried out. In one patient the migration of a stent was detected during the follow up period by using MDCT.

Conclusions

MDCT helps to define stent size, length and type in patients who are suitable for endobronchial stinting. This is a non-invasive, reliable method that helps decisions about optimal stent size and position, thus reducing complications.

Multislice computed tomography angiography in the diagnosis of coronary artery disease

Multislice CT angiography represents one of the most exciting technological revolutions in cardiac imaging and it has been increasingly used in the diagnosis of coronary artery disease. Rapid improvements in multislice CT scanners over the last decade have allowed this technique to become a potentially effective alternative to invasive coronary angiography in patients with suspected coronary artery disease. High diagnostic value has been achieved with multislice CT angiography with use of 64- and more slice CT scanners. In addition, multislice CT angiography shows accurate detection and analysis of coronary calcium, characterization of coronary plaques, as well as prediction of the disease progression and major cardiac events. Thus, patients can benefit from multislice CT angiography that provides a rapid and accurate diagnosis while avoiding unnecessary invasive coronary angiography procedures. The aim of this article is present an overview of the clinical applications of multislice CT angiography in coronary artery disease with a focus on the diagnostic accuracy of coronary artery disease; prognostic value of coronary artery disease with regard to the prediction of major cardiac events; detection and quantification of coronary calcium and characterization of coronary plaques. Limitations of multislice CT angiography in coronary artery disease are also briefly discussed, and future directions are highlighted.

Endodontic management of mandibular second molar fused to a supernumerary tooth, using spiral computed tomography as a diagnostic aid: a case report

Fusion is a developmental anomaly characterized by the union of two adjacent teeth. In this paper we report a rare case of fusion involving permanent mandibular second molar with supernumerary tooth. The rarity with which this entity appears, along with its complex characteristics, often makes it difficult to treat. The use of high-end diagnostic imaging modalities such as spiral computed tomography can help the clinician in making a confirmatory diagnosis and determining the treatment plan before undertaking the actual treatment. In the present case, we have used spiral computed tomography (SCT) for better understanding the complicated root canal morphology of the fused tooth and successful management of this rare case.

Optimization of contrast-enhanced multidetector abdominal computed tomography in sedated canine patients

A major disadvantage of computed tomography for abdominal screening in dogs has been the need for general anesthesia to prevent motion artifacts. With multidetector helical CT, it is possible to decrease examination time, allowing patients to be scanned under sedation. It is also desirable to decrease tube loading to prolong x-ray tube life. To develop a protocol that will allow for examination of sedated patients with minimal image artifacts, milliamperage (mA) and helical pitch were varied, providing 16 experimental scan protocols. A standard clinical protocol was also tested, providing 17 protocols for evaluation. These protocols were tested, using a standard CT phantom, canine tissues in a water bath, and a canine cadaver. The cadaver images were scored semiquantitatively by three reviewers to determine the protocol with the best combination of speed and minimal image artifact. The optimized protocol was then applied to 27 sedated canine patients of three body weight categories. The images obtained were compared to the standard protocol by two reviewers for presence of motion, streak, and quantum mottle artifacts. There was significantly more streak artifact noted by one observer using the optimized study protocol, but no significant difference in any other category. Scanning under sedation was well tolerated in all patients, and sedated CT examination is a promising tool for screening abdominal disease in dogs.

Neuroradiology back to the future: brain imaging

The beginning of neuroradiology can be traced to the early 1900s with the use of skull radiographs. Ventriculography and pneumoencephalography were introduced in 1918 and 1919, respectively, and carotid angiography, in 1927. Technical advances were made in these procedures during the next 40 years that lead to improved diagnosis of intracranial pathology. Yet, they remained invasive procedures that were often uncomfortable and associated with significant morbidity. The introduction of CT in 1971 revolutionized neuroradiology. Ventriculography and pneumoencephalography were rendered obsolete. The imaging revolution continued with the advent of MR imaging in the early 1980s. Noninvasive angiographic techniques have curtailed the use of conventional angiography, and physiologic imaging gives us a window into the function of the brain. In this historical review, we will trace the origin and evolution of the advances that have led to the quicker, less invasive diagnosis and resulted in more rapid therapy and improved outcomes.

Versatility of the cone beam computed tomography in oral surgery: an overview

Cone beam CT (CBCT) produces threedimensional information on the facial skeleton, teeth and their surrounding tissues; and is increasingly being used in many of the dental specialties. This is usually achieved with a substantially lower effective dose compared with conventional medical computed tomography (CT). Periapical pathologies, root fractures, root canal anatomy and the true nature of the alveolar bone topography around teeth may be assessed. CBCT scans are desirable to assess posterior teeth prior to periapical surgery, as the thickness of the cortical and cancellous bone can be accurately determined as can the inclination of roots in relation to the surrounding jaw. The relationship of anatomical structures such as the maxillary sinus and inferior dental nerve to the root apices may also be clearly visualized. Measurements on CBCT are more accurate when compared with OPG. Therefore, CBCT permits the clinician to have all necessary information when planning dental implants. The purpose of this article is to provide an overview of the unique image display capabilities of maxillofacial CBCT systems and to illustrate specific applications in clinical practice.

Diagnostic accuracy of multidetector computed tomography for patients with suspected scaphoid fractures and negative radiographic examinations

PURPOSE

The aim of this prospective study was to evaluate the diagnostic accuracy of multidetector computed tomography (MDCT) in detecting occult scaphoid fractures.

MATERIALS AND METHODS

A total of 54 patients with a clinically suspected scaphoid fracture and negative initial conventional radiographs were evaluated with 64-row MDCT wrist examinations within 1 week of the trauma. The gold standard used was the diagnosis on MRI done within 1 week after MDCT. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MDCT were calculated.

RESULTS

MRI showed a total of 22 fractures in 20 of 55 (36%) wrists. Fractures included 14 scaphoid and 8 other carpal bones. MDCT showed a total of 19 fractures in 17 of 55 (30%) wrists. Two isolated scaphoid fractures and one trapezium fracture were missed on MDCT. The sensitivity, specificity, PPV, and NPV of MDCT were 86%, 100%, 100%, and 91%, respectively.

CONCLUSION

MDCT offers highly accurate results, especially concerning cortical involvement, and is a useful alternative in facilities lacking MRI.

Comparison of neutral and positive enteral contrast media for MDCT enteroclysis

OBJECTIVE

To compare neutral and positive enteral contrast media for MDCT enteroclysis (MDCTE) in various small bowel diseases.

MATERIALS AND METHODS

40 patients with suspicion of small bowel diseases were divided randomly into two equal groups. In one group, water was used as neutral enteral contrast and in other group, 2% water soluble iodinated contrast was used as positive enteral contrast. All MDCTE were done on a 16-slice multidetector row CT unit. The findings of MDCTE were compared with the standards of reference.

RESULTS

There were 12 cases of abdominal tuberculosis (30%), 5 cases of bowel masses (12%), 4 cases of Crohn's disease (10%), 3 cases of small bowel adhesions (7%), 2 cases of midgut volvulus (5%), 2 cases of segmental enteritis (5%) and 12 of all cases (30%) were normal. There was no statistically significant difference between neutral and positive enteral contrast with regards to bowel distention, contrast reflux and evaluation of duodenum. Abnormal bowel wall enhancement was appreciated only with use of neutral enteral contrast (n=12). Evaluation of ileocaecal junction was possible in all 20 patients (100%) with positive enteral contrast but in only 17 patients (85%) with neutral enteral contrast. Overall sensitivity and specificity of MDCTE with use of neutral contrast medium (100 and 88% respectively) was greater for evaluation of small bowel diseases, when compared to MDCTE using positive enteral contrast medium (92.8 and 83.3% respectively).

CONCLUSIONS

Water is a good enteral contrast medium for MDCT enteroclysis examination and allows better evaluation of abnormal bowel wall enhancement. Ileocaecal junction evaluation is better with positive enteral contrast medium.

Utility of multidetector CT and virtual bronchoscopy in tracheobronchial obstruction in children

PURPOSE

The aim of this study was to evaluate the potential use of multidetector CT (MDCT) and virtual bronchoscopy (VB) in the evaluation of tracheobronchial patency in children with suspected bronchial obstruction and to compare its findings with fibreoptic/rigid bronchoscopy or surgery.

PATIENTS AND METHODS

A total of 43 children (15 girls, 28 boys) with clinically suspected bronchial obstruction underwent contrast enhanced MDCT, using an age- and weight- adjusted low dose protocol. Post-processing was performed and VB and multiplanar reformations (MPR) were obtained at the same sitting. Findings obtained at MDCT and VB were compared with fibreoptic/rigid bronchoscopy and surgery.

RESULTS

Obstructive pathology was found in 26 children, which included endoluminal foreign body, mucus plugs in 13 children, endobronchial tumour in three children and extrinsic compression (lymph node, aberrant Vessels, mediastinal cysts/tumours) of the tracheobronchial tree in 10 children. In 17 children, no obstructive lesion was identified. Excellent positive correlation was obtained, between MDCT-VB and bronchoscopy/surgery, however, in one child with endobronchial obstruction caused by tracheitis, low dose MDCT-VB was normal, but bronchoscopy revealed granularity and plaques.

CONCLUSION

MDCT-Virtual bronchoscopy is useful in evaluating bronchial stenosis and obstruction caused by both endoluminal pathology and external compression and has the advantage of looking beyond stenosis. Its main application lies in providing the exact location of suspected foreign body, prior to bronchoscopy. However, it fails to disclose exact nature of obstructing pathology.