Paul I. Mallinson

Artifacts in Dual-Energy CT Gout Protocol: A Review of 50 Suspected Cases With an Artifact Identification Guide

OBJECTIVE The objective of our study was to discover the types and incidence of artifacts in dual-energy CT (DECT) using datasets of 50 consecutive patients who underwent a four-limb DECT protocol for the evaluation of suspected gout. Identification of artifacts and techniques for artifact reduction are discussed. CONCLUSION Artifacts commonly occur in DECT performed for gout assessment but are usually readily recognizable. For 90% of the patients in our study who underwent imaging for suspected gout, DECT showed some type of artifact, with nail bed and skin artifacts being the most common.

Peering through the glare: using dual-energy CT to overcome the problem of metal artefacts in bone radiology.

ObjectiveImaging of patients with large metal implants remains one of the most difficult endeavours for radiologists. This article reviews the theory of dual-energy CT (DECT) and its ability to reduce metal artefact, thus enhancing the diagnostic value of musculoskeletal imaging. The strengths, weaknesses, and alternative applications of DECT, as well as areas requiring further research, will also be reviewed.ConclusionCurrently, DECT stands as the frontier for metal artefact reduction in musculoskeletal imaging. DECT requires no additional radiation and provides significantly enhanced image acquisition. When considered along with its other capabilities, DECT is a promising new tool for musculoskeletal and trauma radiologists.

Dual-energy computed tomographic virtual noncalcium algorithm for detection of bone marrow edema in acute fractures: early experiences.

Abstract Computed tomography (CT) is often used to assess the presence of occult fractures when plain radiographs are equivocal in the acute traumatic setting. While providing increased spatial resolution, conventional computed tomography is limited in the assessment of bone marrow edema, a finding that is readily detectable on magnetic resonance imaging (MRI). Dual-energy CT has recently been shown to demonstrate patterns of bone marrow edema similar to corresponding MRI studies. Dual-energy CT may therefore provide a convenient modality for further characterizing acute bony injury when MRI is not readily available. We report our initial experiences of 4 cases with imaging and clinical correlation.

CT-Guided Percutaneous Cryoablation for Osteoid Osteoma: Initial Experience in Adults

OBJECTIVE The purpose of this study was to investigate the safety and efficacy of CT-guided percutaneous cryoablation for the treatment of osteoid osteoma in adults. MATERIALS AND METHODS A retrospective case series over a 30-month period involved 10 consecutive adult patients (nine male and one female patients; mean age, 27.9 years; age range, 16-49 years) who underwent CT-guided percutaneous cryoablation for management of osteoid osteoma. Clinical and technical success was evaluated with postprocedure MRI at 4-5 weeks and with digital numeric pain scores taken before and immediately after the procedure, as well as at primary follow-up (4-10 weeks; average, 5 weeks) and secondary follow-up (23-29 weeks; average, 24 weeks). RESULTS Clinical and technical success rates were 100%. Average digital numeric pain scores were 7.4 before the procedure, 1.5 after procedure, 0.5 at the primary follow-up, and 0.3 at secondary follow-up. No minor or major complications were noted during the procedure, recovery period, primary follow-up, or secondary follow-up. CONCLUSION CT-guided percutaneous cryoablation is safe and effective in the treatment of osteoid osteoma in adults.

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-

Getting the Most From Your Dual-Energy Scanner: Recognizing, Reducing, and Eliminating Artifacts

OBJECTIVE Dual-energy CT (DECT) is an innovative imaging modality that allows superior detection of pulmonary embolism, enhanced detection of urate in gout, and improved assessment of metal prostheses when compared with conventional CT. CONCLUSION The primary aim of this review is to describe these DECT protocols and compare each to its respective diagnostic reference standards. Moreover, this review will describe how to recognize, reduce, and eliminate DECT artifacts, thereby maximizing its diagnostic capabilities.

Achilles tendinopathy and partial tear diagnosis using dual-energy computed tomography collagen material decomposition application.

Computed tomographic (CT) scans of the ankle and foot are frequently obtained with in-patients with hind foot and ankle pain to identify fractures, arthritis, and bone lesions. Soft tissue detail is limited, however. Dual-energy CT provides additional information on soft tissue structures, including tendons, with no additional radiation dose to the patient. We present a case of an Achilles tendon tear visualized on DECT, which was subsequently confirmed with magnetic resonance imaging.

Malignant granular cell tumor of the foot—multimodality imaging findings and literature review

We describe how the combination of imaging and histologic findings was essential in establishing a preoperative diagnosis of an extremely rare malignant granular cell tumor (GrCT) occurring in the lower extremity of a 17-year-old man. Magnetic resonance imaging demonstrated a large infiltrative tumor of heterogeneous intermediate signal intensity on both T1- and T2-weighted sequences. Subsequent computed tomography (CT) and fluorodeoxyglucose positron emission tomography CT scans of the patient revealed distant nodal and skeletal metastases.

Radiology of Soft Tissue Tumors

Magnetic resonance imaging is the mainstay of diagnostic imaging for soft tissue masses, but plain film, ultrasound, and computed tomography all have roles. A subset of lesions has specific imaging features that enable a confident radiological diagnosis with appropriate clinical correlation. Many soft tissue masses have nonspecific appearances and should be considered for biopsy in a specialist center. When a biopsy is required for definitive diagnosis, careful multidisciplinary planning is essential to avoid contamination of unaffected tissue, leading to recurrence and unnecessary amputations. This article discusses radiological diagnosis, biopsy, and management of the soft tissue mass.

Dual-Energy Computed Tomography: Advantages in the Acute Setting

The aim of this article is to inform and update emergency radiologists in respect of the clinically relevant benefits that dual-energy computed tomography (CT) contributes over conventional single-energy CT in the emergency setting using practical imaging examples. Particular emphasis will be placed on acute gout, bone marrow edema, acute renal colic, acute cardiovascular and neurovascular emergencies aswell as characterization of abdominal incidentalomas. The relevant scientific literature will be summarized and limitations of the technique also will be emphasized to provide the reader with a rounded concept of the current state of technology.