Total imaging matrix reveals new diagnostic possibilities for MRI
16 September 2005
Total imaging matrix (Tim) is a new method of magnetic resonance
tomography introduced by Siemens Medical Solutions in 2004. It allows
whole-body imaging in a single examination with excellent image quality.
Nearly 600 Tim systems have now been installed worldwide and the first
clinical experiences confirm the broad performance spectrum of this
technology.
Tim technology greatly enhances cardiac examinations. The use of a 32
channel coil and new acquisition methods such as AutoViability and Cine Late
Enhancement allow for a display of the infarcted area during heart
contraction, facilitate the examination as such, and improve the diagnosis
of cardiovascular diseases with MR. Not only is it possible to obtain higher
resolution, the workflow shows considerable improvement as well: today, a
full cardiac examination of an infarcted patient can be completed within
15-30 minutes. The in the US already patented technique for precisely
displaying infarcts with Delayed Enhancement, developed together with
Raymond Kim, MD of the Cardiovascular Magnetic Resonance Center at Duke
University, Raleigh Durham, North Carolina, USA, has opened a new field of
indications, as shown by several international cooperation partners who are
now able to diagnose and differentiate various types of cardiomyopathy with
CMR. This examination helps determine the risks of an untreated patient to
die from sudden cardiac death. These statements are confirmed by the work of
Professor Dudley Pennell of the Royal Brompton Hospital in London. This
information can be an important decision-making tool for implanting a
pacemaker.
Pennell was also able to change the invasive therapeutic monitoring of
thalassemia patients — by biopsying the liver — to a non-invasive method
using MR. Thalassemia, a special form of cardiomyopathy, is a genetic
disease prevalent in Mediterranean and Asian countries. Untreated, the
disease is fatal. However, treatment of the disease leads to iron deposits
in the heart and liver which lead to heart failure and sudden cardiac death.
To prevent this outcome, the iron load in the heart has to be checked
carefully. Until now, only biopsies provided the necessary results. But
these were not taken from the heart, but rather from the liver. However,
since the heart is the decisive factor in this disease, the morbidity rate
for patients receiving treatment remained very high. For the first time, it
is now possible to determine the iron contents of the heart in five minutes
with Magnetic Resonance Tomography and Tim. Since it is now possible to
control these effects, the morbidity rate has decreased considerably.
In addition, an examination with Tim allows for a multi territory
assessment through out of cardiovascular diseases throughout the entire body
in a single exam without patient repositioning, for example arteriosclerosis
and diabetes do not affect the heart alone, but other organs and vessel
systems as well. For diabetes, the kidneys in connection with the heart and
the entire vascular system can be examined in a single exam in high
resolution. The physician is able to diagnose vessel changes early and take
therapeutic measures before the heart muscle is damaged.
Although Tim examines patients who are as tall as 6 feet 9 inches, the
technology also offers special advantages when dealing with children: using
measurement techniques such as GRAPPA and T-SENSE combined with the 32 RF
channels of Tim, the fast heart rates of children as well as the smallest
anatomical structures are no longer a challenge. For this reason, Tim
systems are frequently used in specialty hospitals and departments for
paediatric cardiology to diagnose and plan operations for congenital heart
defects. The system allows for a four-dimensional display of the heart and
vessels at an improved spatial resolution of below one millimetre at an even
shorter acquisition time.
In addition to the Magnetom Avanto, other Siemens MR systems are now
equipped with the Tim technology as well. Recently, the first two 3 Tesla MR
systems, the Magnetom Trio, were equipped with Tim and put into operation in
the US and Germany. The Magnetom Espree, the shortest 1.5 Tesla system
worldwide with a very open bore diameter of 70 cm and only 1.25 m length was
introduced last summer. In combination with Tim, the system examines the
effects of overweight and obesity on the heart, vessels and other organs
with a higher image quality than usually obtained with "open" systems.
Overweight people run three times the risk of dying from a heart attack.
Another effect of the systems’ short magnet length is that the patient finds
himself in a larger space. This provides the physician with better access to
the patient, a fact that is of decisive importance during cardiac
examinations using pharmacological stress.
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