Arrow Tech

INTRODUCTION

The purpose of this guide is to give the end-user some insight into problems you can encounter when purchasing pre-owned imaging equipment. This guide is oriented towards MRI systems, but much of the information can be applied to other modalities.

BUDGETING

You can’t always get what you want.

The first question you need to ask is how much are you willing to spend? It does not matter how much you’re budgeting. The project will find a way to absorb all excess funds available. A good rule of thumb is to plan a project and then add 25% for cost overruns.

Once you know how much you can afford to spend on equipment, you can solicit proposals. It will be much easier for you and for the sellers if you are clear on the amount you’re willing to spend before you ask for quotes. It saves time on both sides of the deal and starts the relationship with the reseller off on the right track.

SELECTION

Getting what do you need?

Now that you have a budget set for the equipment, it’s time to consider your options. You can move into low, medium or high-field systems in all price ranges – each with its own tradeoffs.

BENEFITS OF BUYING OLDER EQUIPMENT

Older equipment is less expensive. If you’re willing to use a 5 year or older scanner, you can have it for almost 2 to 3 times less price than new equipment.
Parts for older scanners are much cheaper, so repairs are less expensive. As the price of equipment drops below a certain point, it becomes economically feasible to purchase a unit for parts. This is a huge benefit to the end user because the used parts are usually 25-50% of OEM list

PROBLEMS WITH BUYING OLDER EQUIPMENT

Most older scanners have software that has been "frozen" - there is no ongoing development of new sequences.
The hardware is often obsolete and cannot be upgraded to take advantage of new techniques.
Most older scanners have a lot of wear and tear. However this is less of an issue for MRI systems which have few moving parts.

OPEN VERSUS CLOSED SYSTEMS

Speaking from our experience only, we have found that the Open systems are sometimes difficult to site because they have low tolerance for interferences from the external environment. Superconducting (closed bore) systems - particularly those with active shielding - seem to be much more tolerant of external disturbances like moving automobiles.

If, however, your target patient population includes a high degree of claustrophobic or obese people and have less paying capacity then it is better to move for Permanent magnet open MRI systems. We have heard of patients weighing over 500 lbs. being scanned on the Siemens Open MRI systems.

There is no obvious correlation between open and closed systems with respect to price. It also depends upon already existing MRI systems in your area.

BENEFITS OF OPEN SYSTEMS

Less problem with patient claustrophobia.
Lower field systems have smaller scan area requirements.
You can scan heavier (larger) patients.
Running cost is low as compared to high field superconductor magnet.

PROBLEMS WITH OPEN SYSTEMS

Reduced signal-noise - especially in low field systems. So have low image quality from diagnostic point of view.
Scan time is more as compared to high filed system. For example the T2 Axial sequence has scan time 2-3 minute on 1.0 Tesla system and scan time on 0.3 Tesla is 6-9 minute to get same S/N ratio.
More susceptible to interference from the outside environment.
Generally harder to get good images. Often, you need very specific techniques and/or post-processing for good results.

BENEFITS OF CLOSED SYSTEMS

Better signal-noise - especially in higher field systems
Less susceptible to interference from the outside environment.

PROBLEMS WITH CLOSED SYSTEMS

More problems with patient claustrophobia.
Usually more expensive than open systems.
Running cost is higher than permanent magnet systems because it needs more electricity. It also needs liquid helium for superconductor magnet.

LOWER VERSUS HIGHER FIELD STRENGTH SYSTEMS

The physics of MRI dictates that signal-noise ratio improves as field strength increases. Some imaging techniques benefit more than others. This is an area where your radiologists should be consulted.

In general, higher field strength systems cost more and hold their value longer.

CP and Phased-array coils

Circular-Polarized (CP, aka "quad") coils used two antennas and additional electronics to improve signal-noise. As previously mentioned, radiologists like this because it results in clearer pictures.

CP coils have become so prevalent that they are rarely a cost factor any more.

Phased-array coils incorporate groups of smaller coils. These smaller coils, called elements, usually have higher signal-noise for reasons related to their size. Additional electronics and wiring is installed to allow the use of multiple elements simultaneously. This is most notably demonstrated on a spine array coil which can provide very high quality coverage of the entire spine in a single protocol.

Phased-array systems are significantly more expensive than the systems having no phased array capability.

GRADIENT STRENGTH

This is another area where your radiologists should be consulted. Many advanced imaging techniques like protocols that detect strokes require stronger gradients.

Gradient strength is measured in mT/M. Usually more than 15mT/M is considered good gradient value.In general, higher strength gradients cost more.

SELEW RATE:

The gradieent slew rate is the speed rate of ascent or descent of a gradient from zero to its maximum amplitude, either positive or negative. Which is the amplitude divided by the rise time in msec. Measured in mT/m/msec or T/m/sec.

The shorter the rise time, the faster the gradients and therefore echo spacing. Gradients with a shorter echo spacing will have a better resolution and more slices per TR. The slew rate more than 30 T/m/Sec is considered to be good for Low Field permanent magnet MRI.

COMPUTER POWER

This is pretty much a non-issue in terms of pure speed anymore. Most systems built from 1995 on can calculate images fast enough that it has no effect on patient throughput. You'll spend much more time getting patients on and off the table than waiting for post-processing to finish.

What Do We Offer?

We offer turn key projects including installation, commissioning, after sale maintenance/service of MRI, CT Scanner and Angio-Graphy Systems. We also manufacture RF shielding for MRI suite and fully capable to carry out integrity test of RF shielding as per OEM specifications.

We Offer The Followings Jobs:

1. Site Planning of MRI, CT and Angiography suite.

2. Complete manufacturing, installation and integrity test of RF Cage for permanent and superconductor MRI systems.

3. Vacuum Services of superconductor magnet and cold head replacement.

4. Cooling of superconductor magnet and its ramping.

5. Shimming of superconductor and permanent magnet of some selective Simens and Hitachi MRI Systems.

6. Commissioning of MRI and CT system as per OEM specs.

Tools We Possess:

Arrow-Tech Medical system has following tools to provide above mentioned services.

1. Complete vacuum equipment like dual stage rotary vane pump, turbo molecular pump and digital gauges to measure the high vacuum up to minus 9 Torr.

2. Shimming devices for Impact, Viva and Concerto magnets.

3. Cold Head replacement kit for super conductor magnets.

4. RF Power meter URV-5 to calibrate MRI RF Section.

5. 200 MHz digital scope and Fluke Digital Multi meters.

6. State of the art Digital RF attenuation meter which displays direct digital reading of RF attenuation in db.

7. Impedance meter used for coil tuning of MRI systems.

8. Diagnostic and calibration Software for Toshiba multi-slice CT Scanner and for G.E Scanners to fine tune and troubleshoot the system.

9. Five Laptop computers for engineers having soft copies of all technical manuals.