Recently, 3TP LLC of Southampton, NY, introduced new computer
technology designed to be used with high-resolution
contrast-enhanced magnetic resonance (MR) imaging to help
clinicians determine if specific tissue is benign or malignant.
Using proprietary algorithms on physiologic properties of tissue
enhancement, the "3TP Method" creates a color-coded map indicating
whether areas are malignant, benign, or indeterminate (Figure).
Principles behind the method
"The basic aspects of our method are the way we analyze dynamic
contrast-enhanced MRI," explained developer Hadasa Degani, PhD,
Professor and Chairman, Department of Biological Regulation, the
Weizmann Institute of Science, Rehovot, Israel.
When contrast media is injected into a patient, a dynamic
process takes place, she explained, and this process is the same
regardless of the modality used to monitor the effects.
"Initially," Degani said, "when you inject contrast media, you have
a very high concentration in the blood. Eventually, it leaks out to
many places in the body, including the kidneys and urine, and the
concentration in the blood decreases. In the meantime, some
tissues, particularly cancers because they have very few vessels,
will accumulate contrast media up to a certain level until it is
nearly equal to the level in the blood. It will then go back into
the blood and eventually clear from the body entirely." This
dynamic behavior is generally predictable by mathematical
equations, based on the type of tissue (eg, malignant tumor versus
normal tissue, etc.). These wash-in/wash-out characteristics of
enhancement comprise the first principle behind the 3TP Method.
"The first parameter, the permeability in the surface area of
the blood vessels, is intuitively very simple: If you have more
blood vessels, then you have more permeability and things will move
faster from the blood to the tissue and back," she said.
The second principle behind this system is based on the
extracellular or interstitial volume. "To some extent, if the
contrast agent reaches only the extracellular volume (the
interstitial volume around the cell), then the amount of the
interstitial volume will also dictate the dynamics," said Degani.
"If there is a lot of volume, it will take a long time to fill it
up, and once you do, it will be very pronounced with a lot of
contrast. If you have a little space, then it will reach
equilibrium with the blood very quickly, and it will wash out from
the tissue very quickly."
The second principle is less intuitively easy to understand, but
it is an important independent factor. It tells you how the cells
are packed. If you have many cells, then the interstitial volume is
very small. "It is not as well related to the vascular system, but
is rather related to the structure and growth of tissue," Degani
Although different cancers will have different properties, there
are some common characteristics. "In general, all cancers, not only
breast cancer, have high permeability and high blood-vessel surface
area because of their growth and biology," noted Degani.
"Generally, they are also very heterogeneous and show regions with
lots of cells and regions with few cells."
In order for the clinician to observe all these properties,
however, very high resolution imaging is needed. "In MRI, it is
very difficult to get both high temporal and high spatial
resolution," Degani said. Her research showed, however, that by
taking measurements at just three time points, the physician would
be able to gather the necessary data. "If you monitor at the right
three time points that you chose a priori, then you can extract
this information and maintain very high resolution because you have
time between the time points," she explained. "Three time points
are enough to give you information about distal parameters that
enable you to differentiate between cancerous and benign tumors of
How the 3TP Method works
"Not just any three time points will give you the results you
are looking for, however," she noted. "You need to know which time
points to choose; that is what we determined." Contrast-enhanced
images are taken at three time points within a 7-minute scan. The
first time point is immediately prior to the injection of the
contrast media, the other two are carefully chosen after the
injection of contrast media. A "wash-in:wash-out" ratio and a
color-coded calibration map are established.
"We color-coded the results so that the analysis will
immediately reveal where there is cancer and where it is benign,"
continued Degani. "Essentially, we solve how to choose the three
time points and how to standardize the methods so users can work
with different contrast agents or different modalities." The system
works regardless of contrast agent or imaging modality because it
is based on physiological parameters, and these parameters for
patients with breast cancer are always within the same range.
To date, this method is approved in the United States for use
with MR imaging of the breast and the prostate. "We developed this
primarily for breast cancer and performed many clinical trials in
the breast," stated Degani. "We may need a little more experience
with the prostate; but, in certain areas of the prostate,
particularly in the peripheral zone of the prostate and for staging
of prostate cancer, it is very clear."
"The sensitivity of MRI is by far much higher than any other
modality and it picks up many more lesions than mammography, but
most of them are benign," she explained. "If we use MRI for breast
cancer without high specificity, the incidence of unnecessary
biopsy will be too high. This method offers a method with very high
sensitivity and specificity."
"This method can be used with MRI and with other methods that
use intravenous contrast, such as CT and ultrasound," she
concluded. "For CT, I think it's even more important to use this
method because CT offers high temporal and spatial resolution, but
you can't expose the patient to radiation too many times. So
determining the minimum scanning time to get the maximum
information is essential."
Degani also noted that they have developed a method for using
this system with CT for the detection of lung cancer. "We use the
same principles with CT. It works, but it's very preliminary and we
haven't published it yet," she said.
Siemens to introduce Tim to Europe at ECR 2004
Siemens AG (Munich, Germany) will be showcasing the company's
new Tim (Total imaging matrix) MRI technology on its new 1.5T MR
system, the Magnetom Avanto, at the European Congress of Radiology
(ECR 2004) in Vienna, Austria, March 5-9. This new technology
allows whole-body imaging to be completed within 12 minutes without
the need to change coils or reposition the patient.
The basis of Tim is a proprietary matrix coil design that allows
for a combination of 76 coil elements with up to 32 radiofrequency
channels. This technology provides a scanning area up to 205 cm,
enabling whole-body scanning of a patient up to 6′ 9″ tall in a
single examination. The coil, called the Body Matrix coil, weighs
In addition, with Tim and the Magnetom Avanto system, the
patient can be scanned feet first, allowing the patient's head to
remain outside the scanner for many procedures. The system also
uses AudioComfort noise suppression that reportedly reduces
conventional noise levels up to 97%.
The new system is based on the company's syngo platform, which
also features the company's iPAT (integrated Parallel Acquisition
Technique) that allows for fast image acquisition and parallel
imaging in all directions across the body without the need for the
specific PAT coils. The user is able to select clinically relevant
areas-from individual body regions to the complete anatomy-without
limitations on the number of coils that can be connected and used
"Tim enables us to set aside all previous levels of
intricateness," said Claus D. Claussen, MD, director of the
Diagnostic Radiology Department at the University Hospital Tübingen
and Chairman of Radiology at Eberhard-Karls-University, Tübingen,
Germany. "As a result, the clinical workflow is greatly improved,
enabling a far better patient throughput and excellent image
resolution and, thus, optimal image quality."
Tim is now a standard feature on the Magnetom Avanto and is
available as an upgrade on the company's Magnetom Symphony, Sonata,
and Trio lines.