MRI technology, Next Ten years!

By : Som Panicker, Vice President of Sanrad.
Email: som@sanrad.in
Posted on: Tuesday, July 10, 2012


For most of  us ,It is very  difficult to imagine  today that the first  MRI   took more than 4 hours to  reconstruct the  image  as  even the  color  rendered 3D images from an MRI can  come within seconds .  It is almost 35 years  since  MRI  examination took place  and today  MRI  become  one of the most  important  examination in diagnostic radiology  even though  it has no radiation.

Approximately 50  Millions  MRI examinations  are  being done  every year worldwide  and  this phenomenal growth  imitated  by  ever increasing  number of   diagnostic applications  developed for  MRI  technology and the radiation   free  application  to patients .

As  mentioned earlier,  radiation free  and non invasive make MRI  examination one of the most preferred  technique   providing  high resolution  imaging  of soft tissues  of various anatomy like  Brain,  spine,  abdomen,  breast, prostrate  or even blood.

Over   the past few years  several  improvements  are  done  on almost  every single component  of the  MRI  equipment  and  its applications  making the   technology  used for many  special applications  improving both scan time  as well as  image quality.  Today an MRI can perform imaging of coronary vessels of heart which was unimaginable till few years back.

Let me briefly mention   few areas where maximum developments are being done and it will be nice to imagine what is in store for next 10 years.

Magnet

There are mainly 4 types of   magnets  used in MRI  and they are

1.            Permanent Type   upto  0.7T

2.            Resistive iron Type   upto 0.7T

3.            Superconducting Type   upto 7T

4.            Hybrid type –Super conductive open  upto 1.2T

Over the past few years, superconducting MRIs are merged as the most preferred type of MRIs for diagnostic purpose all over the world.  But permanent magnets being cost effective and low maintenance gained popularity in many   countries including India.  Hybrid type Magnets are patient friendly but very expensive to buy and maintain.

The most interesting development in Magnet technology is the normal temperature superconducting magnets where there is no need of cooling  using Liquid helium  . Already  high temperature  Superconducting  magnets  ( HTS)  are  developed  upto 0.5T and  many  firms are working a commercially  viable  normal temperature  superconducting 1.5T  MRI .  If this  comes true  it will change the  entire  MRI  magnet technology and that will  be  the biggest change in next 10 years

Very high Tesla  Imaging

There was a time  we  could  not imagine  a magnetic field beyond 0.5 T and  today the  scope of high  filed  imaging starts at  1.5T and  experimental MRI  models with 7T are already  ready for  using human scans  .  Very high Tesla imaging  at 7T or 11T  may be  regarded as  unnecessary today  but  applications  for very high  Tesla  imaging   are also increasing  like  functional studies  and other high end   neuro  applications .

Ultra fast  scanning

Ultrafast MRI utilizes multi channel (eight or more ), phase-array brain coils, which increase the speed of image gathering but does not reduce the quality of the images. Conventional MRIs may be used in a rapid format but this has the effect of reducing the quality of the image.

Ultrafast MRI has been cited as a useful diagnostic tool for patients suspected of suffering a stroke. Lot of  MRI vendors are working  in this area  and  ultrafast  sequences  will be a standard feature  in coming years.

Multi Transmitter coils

This new type of MRI technology will feature all of the image collection qualities of standard 1.5 Tesla MRI systems, but with the signal-to-noise (SNR) advantages of a very high field MRI scanner.

Almost every MRI vendor today has some or other multi transmitter technology and more no of channels are being introduced every year.

This new technology will solve many of the problems associated with very high field MR imaging such as non-uniform excitation and high RF power deposition (SAR). Cardiac MRI  is a typical  example to benefit from this technology .

Parallel Imaging

In parallel MR imaging, a reduced data set in the phase encoding direction(s) of k-space is acquired to shorten acquisition time, combining the signal of several coil arrays.

Reconstruction of the Fourier plane of images from the frequency signals of each coil (reconstruction in the frequency domain, before Fourier transform): GRAPPA.

Additional techniques include SMASH, SPEEDER™, IPAT (Integrated Parallel Acquisition Techniques – derived of GRAPPA a k-space based technique) and mSENSE

Non-Contrast  Angio

Non-contrast MR Angiography  is an upcoming  facility offered  by many of the  vendors like Toshiba, Siemens , GE etc. ,  One example offered by Siemens  is based on the TrueFISP (True Fast Imaging with Steady state Precession) sequence, which is a balanced steady state gradient echo technique. The contrast mechanism for  TrueFISP comes from the preparation of the imaging volume with a spatially selective inversion pulse, resulting in the suppression of stationary tissue within the imaging volume and suppression of signal from blood in the imaging volume (e.g. venous blood). The contrast is further enhanced by the suppression of the background by the inversion pulse.

Non contrast  MR Angiography can be a standard feature  in  most of the MRI  in next  few years

MRI  HIFU

In recent times  the therapy use of ultrasound combined with  the naviagation done with the help of MRI  resulted in  MRgFUS or  MRI  HIFU( MR guided Focused ultrasound or MRI high intensity Focused ultrasound) ) .  HIFU is used  presently treating Fibroids and many forms of cancer  and  lot of  developments are  being dome including the  use of HIFU  for treatment of  brain tumor  and other types of cancer cells . This technique is relatively safe and radiation free hence attracted lot of attention in recent times.   MRI HIFU could be a standard treatment mode in next 10 years.

MRI PET

As name suggests , a combination of fusing of  PET with MRI images  from  single equipment  is a novel  idea and it has lot of advantages  even though the initial investment  as well as  maintenances  is  high  at this moment.   Many MRI vendors rolled out their MRI PET in recent times and lot of advancement is expected in this area in next 10 years.

In short, MRI  with all its clinical and functional advantages ,  undoubtedly  will progress further  into a  very  essential  imaging  modality  in next 10 years .

The future is certainly bright for MRI – be it in traditional diagnostic imaging, in therapy, or on a molecular level.