Luck J. Louis

Dual-Energy CT as a Potential New Diagnostic Tool in the Management of Gout in the Acute Setting

OBJECTIVE Gout is the most common crystal deposition arthropathy currently diagnosed clinically and with arthrocentesis. Dual-energy CT is a promising new imaging technique offering potential new applications in a number of clinical areas. CONCLUSION The ability of dual-energy CT to diagnose early gout and its use as a problem-solving tool is shown here. Diagnosis of subclinical gout could avert associated long-term complications, thereby reducing disease burden and improving overall quality of life.

Musculoskeletal Ultrasound Intervention: Principles and Advances

Ultrasound scan is an invaluable tool in the diagnosis and treatment of disorders of the musculoskeletal system. Core concepts that are common to most ultrasound-guided procedures are reviewed, including an in-depth discussion regarding the use of injectable corticosteroids. Various aspects of intra-articular, intratendinous, bursal, and ganglion cyst intervention are discussed and promising advances in the treatment of chronic tendon disorders are presented.

Vancouver simplified grading system with computed tomographic angiography for blunt aortic injury

OBJECTIVE Delineation of blunt aortic injury by computed tomographic angiography guides management of this potentially fatal injury. Two existing grading systems are problematic to apply and not linked to outcomes. A simplified computed tomographic angiography-based grading system, linked to clinical outcomes, was developed, and feasibility and reliability were evaluated. METHODS Retrospective review was performed of all blunt aortic injury cases presenting to a single provincial quaternary referral center designated for blunt aortic injury management between 2001 and 2009. Management, associated injuries, hospital survival, and cause of death were determined. Initial computed tomographic angiography was reviewed, and injuries were graded according to the new Vancouver simplified grading system by 2 study authors. Three additional trauma radiologists then graded the aortic injuries with the 2 existing systems and the simplified system. Interrater reliability was determined. RESULTS Forty-eight patients were identified. Two had minimal aortic injury (grade I), 7 had an intimal flap larger than 1 cm (grade II), 32 had traumatic pseudoaneurysm (grade III), 6 had active contrast extravasation (grade IV), and 1 could not be rated. Survivals were 100%, 90%, and 33% for grades I and II, III, and IV, respectively. Of grade III injuries, 14% were medically managed, 68% repaired endovascularly, and 18% repaired with open surgery. Interrater correlation was best with the simplified score, with only 0.5% of cases unable to be classified. CONCLUSIONS The Vancouver simplified blunt aortic injury grading system is easy to use and correlates with clinical outcomes. Prospective external validation is required.

The emergence of ultra-low--dose computed tomography and the impending obsolescence of the plain radiograph?

Until recently, computed tomographic (CT) examinationsacquired at a radiation exposure equivalent to correspondingplain radiographs would be of grossly substandard imagequality, almost certainly resulting in a failure to adequatelyvisualize many anatomic structures. Over the past decade,successive technical breakthroughs have facilitateddiagnostic-quality CTs to be acquired at rapidly decliningionizing radiation exposures. Today, the mean effectivedose of a radiographic series of the abdomen at 0.7 mSv,pelvis at 0.6 mSv, thoracic and lumbar spine at 1.0 and1.5 mSv, respectively [1] appear licentious when comparedwith exposures achieved in recent low-dose CT trials(Table 1). In an era in which low-dose CT has facilitateda 20% reduction in mortality among smokers [7]. and inwhich doses continue to substantially fall, we propose thatradiologists and clinicians should critically reevaluate therisks and benefits of performing many plain radiographicexaminations.Technical BackgroundIn brief summary, there have been 3 key developments inCT dose reduction technology that have facilitated theaforementioned trend. Automated exposure control ensuresefficient dose delivery by modulating tube current accordingto patient width and attenuation profile [8e10]. Fixed tubecurrent settings were commonplace in older-generation CTsystems and resulted in wider, more attenuating areas, suchas the shoulders receiving the same exposure as narrower lessattenuating regions such as the upper lungs. More recently,algorithms that modulate CT voltage according to patientsize and CT application have also been implemented withgood success [11].After ensuring efficient dose delivery, the largest chal-lenge to obtaining diagnostically acceptable CT images atexposure levels similar to plain radiographs is the severity ofrandom variation in attenuation values that occur within thenormal anatomic structures in these images otherwiseknown as noise. The magnitude of image noise at low CTexposure is fundamentally related to the image reconstruc-tion process [12]. Iterative reconstruction algorithms usea varyingly complex model of the physical characteristics ofthe x-ray tube, beam, and the 3-dimensional interaction ofthe x-ray beam within the patient to reduce noise and areclearly better than more traditional methods of reconstruc-

Detection of Bone Marrow Edema in Nondisplaced Hip Fractures: Utility of a Virtual Noncalcium Dual-Energy CT Application

Purpose To quantify the sensitivity and specificity of dual-energy computed tomographic (CT) virtual noncalcium images in the detection of nondisplaced hip fractures and to assess whether obtaining these images as a complement to bone reconstructions alters sensitivity, specificity, or diagnostic confidence. Materials and Methods The clinical research ethics board approved chart review, and the requirement to obtain informed consent was waived. The authors retrospectively identified 118 patients who presented to a level 1 trauma center emergency department and who underwent dual-energy CT for suspicion of a nondisplaced traumatic hip fracture. Clinical follow-up was the standard of reference. Three radiologists interpreted virtual noncalcium images for traumatic bone marrow edema. Bone reconstructions for the same cases were interpreted alone and then with virtual noncalcium images. Diagnostic confidence was rated on a scale of 1 to 10. McNemar, Fleiss κ, and Wilcoxon signed-rank tests were used for statistical analysis. Results Twenty-two patients had nondisplaced hip fractures and 96 did not have hip fractures. Sensitivity with virtual noncalcium images was 77% and 91% (17 and 20 of 22 patients), and specificity was 92%-99% (89-95 of 96 patients). Sensitivity increased by 4%-5% over that with bone reconstruction images alone for two of the three readers when both bone reconstruction and virtual noncalcium images were used. Specificity remained unchanged (99% and 100%). Diagnostic confidence in the exclusion of fracture was improved with combined bone reconstruction and virtual noncalcium images (median score: 10, 9, and 10 for readers 1, 2, and 3, respectively) compared with bone reconstruction images alone (median score: 9, 8, and 9). Conclusion When used as a supplement to standard bone reconstructions, dual-energy CT virtual noncalcium images increased sensitivity for the detection of nondisplaced traumatic hip fractures and improved diagnostic confidence in the exclusion of these fractures.

Hypovolemic Shock Complex in the Trauma Setting: A Pictorial Review

Hypovolemia is defined as the physiological state of Taylor et al [5] initially described the HSC or hyporeduced blood or, more specifically, reduced plasma volume. When volume loss is severe, many homeostatic mechanisms serve to maintain adequate tissue perfusion to critical organs, such as the brain and the heart. These compensatory mechanisms can result in a severe reduction of vascular perfusion and oxygen delivery to numerous other vital organs, such as the liver and the kidneys, which may ultimately lead to multiorgan failure. Key steps in the initial management of hypovolemic shock include determining the severity of volume loss, appropriate volume resuscitation, and accurate identification of the underlying cause. The severity of shock can be graded based on the scale of derangement in vital signs, such as heart rate and blood pressure, and by the presence and severity of clinical signs and symptoms, such as pallor, tachypnea, and a reduced level of consciousness. Classification schemes often use a 4or 6-point scale and have been shown to improve patient management and outcome [1e3]. The subgroups and major causes of hypovolemic shock are summarized in Table 1 [4]. In contemporary practice, patients with hypovolemic shock related to hemorrhagic traumatic causes are frequently evaluated by using computed tomography (CT). Although the primary aim of CT in patients with hemorrhagic traumatic shock is to identify the exact site of blood loss and to direct appropriate treatment of traumatic injuries, accurate recognition of a constellation of secondary CT findings termed the hypovolemic shock complex (HSC) also allows radiologists to contribute significantly towards the clinical grading of shock severity.

The utilization of dual source CT in imaging of polytrauma

Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner.

Get a kick out of this: the spectrum of knee extensor mechanism injuries

At the end of this article, the reader should be able to (1) recognise normal anatomy and anatomical variants of the extensor mechanism of the knee on various imaging modalities, including plain film, ultrasound and MRI; (2) diagnose a broad spectrum of EM injuries in adult and paediatric patients including patellar and quadriceps tendinopathy, Osgood–Schlatter disease, Sindig–Larsen–Johansson syndrome, chondromalacia patellae and patellar fractures on various imaging modalities; and (3) appreciate the important role of imaging in the diagnosis of musculoskeletal injuries.

Review of Multidetector Computed Tomography Angiography as a Screening Modality in the Assessment of Blunt Vascular Neck Injuries

Blunt vascular neck injuries (BVNI), previously thought to be rare, have demonstrated increasing incidence rates in recent literature and are associated with significant mortality and morbidity. A radiologist needs to efficiently recognize these injuries on preliminary screening to enable initiation of early management. When initiation of accurate management is started promptly, decreased rates of postinjury complications, for example, stroke, have been demonstrated. This article reviews the incidence, pathophysiology, and rationale for screening for these BVNI injuries. The utility of computed tomography angiography (CTA) as the potential new criterion standard as the screening and follow-up imaging modality for BVNI will be discussed. The application of new multidetector CTA techniques available, such as dual-energy CT and iterative reconstruction, are also reviewed. In addition, the characteristic imaging findings on CTA and the associated Denver Grading scale for BVNI will be reviewed to allow readers to become familiar with the injury patterns and to understand the prognostic and clinical implications, respectively. Examples of the spectrum of injuries, potential injury mimics, and different artifacts on multidetector CTA are shown to help familiarize readers and allow them to successfully and confidently recognize a true BVNI.

Rotator cuff troublemakers: pitfalls of MRI and ultrasound

Rotator cuff pathology is routinely evaluated in many imaging centers with both magnetic resonance imaging (MRI) and ultrasound. Despite good diagnostic accuracy using each of these modalities, certain limitations persist. In this pictorial essay, we describe five potential “troublemakers” of rotator cuff pathology which are recurrent themes in our busy shoulder referral center. The comparison of imaging findings on MRI and ultrasound are discussed. An awareness of these potential pitfalls will help improve radiologists’ diagnostic accuracy of rotator cuff pathology, and allow the clinician to optimize imaging referral and better interpret the subsequent report.