Showing papers by "Adnan Sheikh published in 2019"

Applying Modern Virtual and Augmented Reality Technologies to Medical Images and Models

Abstract: Recent technological innovations have created new opportunities for the increased adoption of virtual reality (VR) and augmented reality (AR) applications in medicine While medical applications of VR have historically seen greater adoption from patient-as-user applications, the new era of VR/AR technology has created the conditions for wider adoption of clinician-as-user applications Historically, adoption to clinical use has been limited in part by the ability of the technology to achieve a sufficient quality of experience This article reviews the definitions of virtual and augmented reality and briefly covers the history of their development Currently available options for consumer-level virtual and augmented reality systems are presented, along with a discussion of technical considerations for their adoption in the clinical environment Finally, a brief review of the literature of medical VR/AR applications is presented prior to introducing a comprehensive conceptual framework for the viewing and manipulation of medical images in virtual and augmented reality Using this framework, we outline considerations for placing these methods directly into a radiology-based workflow and show how it can be applied to a variety of clinical scenarios

The Dixon technique for MRI of the bone marrow

Abstract: Dixon sequences are established as a reliable MRI technique that can be used for problem-solving in the assessment of bone marrow lesions. Unlike other fat suppression methods, Dixon techniques rely on the difference in resonance frequency between fat and water and in a single acquisition, fat only, water only, in-phase and out-of-phase images are acquired. This gives Dixon techniques the unique ability to quantify the amount of fat within a bone lesion, allowing discrimination between marrow-infiltrating and non-marrow-infiltrating lesions such as focal nodular marrow hyperplasia. Dixon can be used with gradient echo and spin echo techniques, both two-dimensional and three-dimensional imaging. Another advantage is its rapid acquisition time, especially when using traditional two-point Dixon gradient echo sequences. Overall, Dixon is a robust fat suppression method that can also be used with intravenous contrast agents. After reviewing the available literature, we would like to advocate the implementation of additional Dixon sequences as a problem-solving tool during the assessment of bone marrow pathology.

Encapsulating Peritoneal Sclerosis: The Abdominal Cocoon.

Abstract: Encapsulating peritoneal sclerosis (EPS) is a rare but serious condition that results in (a) encapsulation of bowel within a thickened fibrocollagenous peritoneal membrane and (b) recurrent episodes of bowel obstruction. Although described by various names in the literature, the preferred term is encapsulating peritoneal sclerosis because it best describes the morphologic and histologic changes in this disorder. The etiology of EPS is multifactorial, with a wide variety of implicated predisposing factors that disrupt the normal physiologic function of the peritoneal membrane-prime among these factors being long-term peritoneal dialysis and bacterial peritoneal infections, especially tuberculosis. The clinical features of EPS are usually nonspecific, and knowledge of the radiologic features is necessary to make a specific diagnosis. The findings on radiographs are usually normal. Images from small-bowel follow-through studies show the bowel loops conglomerated in a concertina-like fashion with a serpentine arrangement in a fixed U-shaped configuration. US demonstrates a "cauliflower" appearance of bowel with a narrow base, as well as a "trilaminar" appearance depicted especially with use of high-resolution US probes. CT is the imaging modality of choice and allows identification of the thickened contrast material-enhanced abnormal peritoneal membrane and the encapsulated clumped bowel loops. In addition, CT can potentially help identify the cause of EPS (omental granuloma in tuberculosis), as well as the complications of EPS (bowel obstruction). Conservative medical treatment and surgical therapy early in the course of EPS have been used for management of the condition. The purpose of this article is to review the nomenclature and etiopathogenesis of EPS, describe the multimodality imaging appearances of EPS, including differentiating its features from those of other conditions mimicking EPS, and give an overview of management options. Online DICOM image stacks are available for this article. ©RSNA, 2018.

Capsular needle biopsy as a pre-operative diagnostic test for peri-prosthetic shoulder infection:

Abstract: Background Establishing the diagnosis of peri-prosthetic shoulder infection prior to revision shoulder arthroplasty can be difficult. The objectives of the present study were (i) to describe the technique of fluoroscopic capsular needle biopsy for the diagnosis of peri-prosthetic shoulder infection and (ii) to determine the feasibility and preliminary accuracy of the test in a pilot sample of patients undergoing revision shoulder arthroplasty. Methods Eighteen patients, comprising eight females and nine males with a mean age of 61 years (range 37 years to 81 years) underwent capsular needle biopsy during the work-up of suspected chronic arthroplasty-related glenohumeral infection. Intra-operative tissue samples were taken from a minimum of three regions of the joint capsule during revision surgery. Standard serum indices were obtained. Results Of 17 patients with possible infection, five had confirmed culture positive infections based on intra-operative biopsies. Of these five patients, four (80%) had positive cultures from fluoroscopic capsular needle biopsy, with matching cultures. There were no complications. No culture-positive patients had elevated serum indices for infection. Conclusions The technique for fluoroscopic capsular needle biopsy appears to be feasible and the preliminary results for this technique appear to be promising, with a sensitivity of 80% and a specificity of 100%.Level of evidence: Level II: diagnostic test.

Marrow adipose tissue gradient is preserved through high protein diet and bed rest. A randomized crossover study.

Abstract: Context Marrow adipose tissue (MAT) has a peripheral to central distribution in adults, higher in peripheral bones. Similarly, the spine has a caudal to cephalad MAT distribution, higher in lumbar vertebras. Diet and the level of physical activities are known modulators of MAT with significant impact on bone; however, whether these can modulate the MAT gradient is unknown. Objective To measure the effect of high protein diet and bed rest interventions on the lumbar MAT gradient. Design, participants, intervention In a prospective randomized crossover trial, 10 healthy men participated in 2 consecutive campaigns of 21days head-down-tilt-bed-rest (HDTBR). They received either whey protein and potassium bicarbonate-supplemented or control diet separated by a 4-month washout period. Main outcome measure(s) Ten serial MRI measures of lumbar vertebral fat fraction (VFF) were performed at baseline, 10days and 20days of HDTBR and 3 and 28days after HDTBR of each bed rest campaign. Results The mean L5-L1 VFF difference of 4.2 ± 1.2 percentage point higher at L5 (p = 0.008) constituted a caudal to cephalad lumbar MAT gradient. High protein diet did not alter the lumbar VFF differences during both HDTBR campaigns (all time points p > 0.05). Similarly, 2 campaigns of 21days of HDTBR did not change the lumbar VFF differences (all time points p > 0.05). Conclusions This pilot study established that the lumbar vertebral MAT gradient was not altered by a high protein nor by 2 × 21days bed rest interventions. These findings demonstrated that this lack of mechanical stimulus was not an important modulator of the lumbar MAT gradient. The highly preserved MAT gradient needs to be measured in more situations of health and disease and may potentially serve to detect pathological situations.

Playboy bunny sign.

Abstract: 1 Department of Radiology, Al-Wakra Hospital, Hamad Medical Corporation, PO Box: 82228, Doha, Qatar 2 Department of Radiology, Weil Cornell Medical College, Doha, Qatar 3 Department of Medical Imaging, The Ottawa Hospital, Civic Campus, 1053 Carling Avenue, Ottawa, Ontario K1Y 4E9, Canada Fig. 1 Image of playboy bunny logo. Source https ://pixab ay.com/en/ playb oy-bunny -logo-club-men-s-club-42527 /. Accessed 19 November 2018 “Playboy bunny sign” describes the appearance of dilated hepatic veins and intrahepatic inferior vena cava (IVC) in congestive heart failure on abdominal ultrasound [1, 2]. The word “Bunny” is used to describe the young rabbit informally (Fig. 1). In passive hepatic congestion, the dilated IVC and dilated hepatic veins mimic the head and ears of a bunny (Fig. 2). It was originally called as “Playboy bunny sign” in 1983 by Bartrum and Crow to describe the confluence of hepatic veins with IVC in normal subjects [3]. ‘Playboy Bunny’’ refers to the waitress in the famous playboy clubs who wore bunny suits. Other names for this appearance include moose’s head and Deer’s horns sign [2]. Although ‘Playboy Bunny’ was originally described for the appearance of normal hepatic venous confluence, it is now being used to denote the dilated hepatic veins at the confluence typically seen in passive hepatic congestion. Passive hepatic congestion refer to the dilatation of hepatic veins and intrahepatic IVC with venous stasis due to elevated central venous pressure from various cardiopulmonary diseases like congestive heart failure, constrictive pericarditis, cardiomyopathy, tricuspid regurgitation, and cor pulmonale. Chronic hepatic congestion leads to hypoxia and eventual hepatocyte injury resulting in cardiac cirrhosis. Patients present with classical features of cardiac failure and can have right upper quadrant pain due to stretching of liver capsule for congestive hepatomegaly [4]. Ultrasound is a useful modality in the diagnosis of congestive hepatomegaly in patients presenting with right upper quadrant pain or elevated liver enzymes. Classical findings included dilated hepatic veins (> 6 mm), dilated

Medical Innovation Taking Form: 3D Printing at The Ottawa Hospital

Abstract: Three-Dimensional (3D) printing is an emerging medical technology with capacity to revolutionize multitude aspects of clinical care and medical education. This commentary highlights The Ottawa Hospital Medical 3D Printing Program, a leading Canadian site for the manufacturing of 3D-printed clinical solutions. In Ottawa, 3D printing has already been employed to optimize preoperative surgical planning, facilitate communication with patients, and enhance medical learning and outreach efforts. Rapid advances in manufacturing technology are poised to further expand current medical applications of 3D printing nation-wide.