Biography

My research is concentrated on the development of image-guided therapies. In particular, I have focused on the biomedical applications of HIFU (High-Intensity Focused Ultrasound). Ultrasound is an attractive form of energy for therapeutic use since it can be transmitted through the body from external transducers, can be focused to very localized regions of a few mm, and can be generated from devices of multiple geometries ranging from large focused transducers to catheter based devices. A unique set of capabilities arises when this technology is combined with magnetic resonance imaging (MRI). The ultrasound technology is able to non-invasively deliver energy within the body for applications such as mild heating or tissue ablation, and MRI is able to acquire images of the temperature distribution in the heated tissues during heating. Since the relationship between temperature, time and cell kill is well established, this creates a powerful closed loop method for treating soft tissues.

The other emerging application of HIFU is to potentiate or enable targeted delivery of agents within the body. Ultrasound can be used to trigger release from temperature sensitive liposomes, or to non-invasively open the blood brain barrier. These capabilities open up many possibilities for targeted drug delivery in the brain and other organs with pre-existing vascular barriers (retina, testicles, placenta, etc).

My research has a preclinical component focused on novel applications of HIFU, and a translational component aimed at evaluating established HIFU approaches in patients.

Education

Undergraduate Mcmaster University (1996), Physics
Graduate School University of Toronto - Canada (2002), Biophysics

Research Interest

  • Enhancement of radiation and chemotherapy using MRI-controlled HIFU
  • Image-guided drug delivery to the brain using ultrasound energy
  • Non-invasive tissue ablation and hyperthermia using high-intensity focused Ultrasound (HIFU)

Publications

Featured Publications LegendFeatured Publications

MR Imaging-controlled Transurethral Ultrasound Therapy for Conformal Treatment of Prostate Tissue: Initial Feasibility in Humans.

Chopra R, Colquhoun A, Burtnyk M, N'djin WA, Kobelevskiy I, Boyes A, Siddiqui K, Foster H, Sugar L, Haider MA, Bronskill M, Klotz L Radiology 2012 Oct 265 1 303-13

Arterial input function calculation in dynamic contrast-enhanced MRI: an in vivo validation study using co-registered contrast-enhanced ultrasound imaging.

Mehrabian H, Chandrana C, Pang I, Chopra R, Martel AL Eur Radiol 2012 Aug 22 8 1735-47

Coagulation of human prostate volumes with MRI-controlled transurethral ultrasound therapy: results in gel phantoms.

N'djin WA, Burtnyk M, Kobelevskiy I, Hadjis S, Bronskill M, Chopra R Med Phys 2012 Jul 39 7 4524-36

Real-time correction by optical tracking with integrated geometric distortion correction for reducing motion artifacts in functional MRI.

Rotenberg D, Chiew M, Ranieri S, Tam F, Chopra R, Graham SJ Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine 2012 May

Hyperthermia in bone generated with MR imaging-controlled focused ultrasound: control strategies and drug delivery.

Staruch R, Chopra R, Hynynen K Radiology 2012 Apr 263 1 117-27

Hyperthermia in Bone Generated with MR Imaging-controlled Focused Ultrasound: Control Strategies and Drug Delivery.

Staruch R, Chopra R, Hynynen K Radiology 2012 Feb

Thermally-triggered 'off-on-off' response of gadolinium-hydrogel-lipid hybrid nanoparticles defines a customizable temperature window for non-invasive magnetic resonance imaging thermometry.

Shuhendler AJ, Staruch R, Oakden W, Gordijo CR, Rauth AM, Stanisz GJ, Chopra R, Wu XY J Control Release 2012 Feb 157 3 478-84

Investigation of power and frequency for 3D conformal MRI-controlled transurethral ultrasound therapy with a dual frequency multi-element transducer.

N'djin WA, Burtnyk M, Bronskill M, Chopra R Int J Hyperthermia 2012 28 1 87-104

The feasibility of endorectal MR elastography for prostate cancer localization.

Arani A, Plewes D, Krieger A, Chopra R Magn Reson Med 2011 Dec 66 6 1649-57

Development of a platform for co-registered ultrasound and MR contrast imaging in vivo.

Chandrana C, Bevan P, Hudson J, Pang I, Burns P, Plewes D, Chopra R Phys Med Biol 2011 Feb 56 3 861-77