Why Only Two Relaxation Times

The relaxation times T1 and T2 were described phenomenologically by Felix Bloch at al representing changes in the net magnetization (M) after RF-stimulation. T1 reflects changes along the direction (z-) of the main magnetic field; T2 reflects transverse (xy-) behavior. There are only two relaxation times because the directions “longitudinal” and “transverse” seem to encompass the cardinal directions in three-dimensional space. The transverse (x- and y-) directions are generally arbitrary and indistinguishable so only a single T2 value is usually applied.
However, some tissues and materials have T2 anisotropy, meaning their observed T2 values differ depending on orientation, so I suppose you could say there are more than one transverse relaxation time for these substances, but they are still called T2’s.
Additionally, in the rotating frame another type of relaxation time is frequency distinguished, T1ρ (“T1-rho”). This relaxation time is somewhat of a hybrid between T1 and T2 that can be measured in when a spin-locking pulse is applied to a system. See our paper from 1996 for further explanation:
Ulmer JL, Mathews VP, Hamilton CA, Elster AD, Moran PR. Magnetization transfer or spin-lock? An investigation of off-resonance saturation pulse imaging with varying frequency offsets. AJNR Am J Neuroradiol 1996.
I have never heard of the “duality” explanation above; it is not correct at all and should be abandoned/discouraged.
PQ001 MRI Contrast Agent Analyzer

Product Description:

The PQ001 NMR Analyzer was launched in 2008. After years of upgrading, PQ001 has many advantages such as small size, high precision, good repeatability, good stability and excellent cost/benefit performance. Based on these advantages, PQ001 has been widely used in MRI Contrast Agent Researches.

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Basic Parameters:

• Magnet: permanent magnet
• Magnetic field intensity:0.5±0.08T
• Probe: Ø15mm
• Size (L x W x H): 1685mm×520mm×386mm
• Weight: 134Kg

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Functions:

• Relaxation analysis of T2*,T2 and T1

Review Questions for MRI

I was rattled by the numerous errors contained in the first version. While this version has supposedly been corrected, novices like me would do well to proceed cautiously. I suppose there is some value in looking up the answers from an independent and more reliable source but I doubt most people buying a review book would want to do so

That being said, the book is comprehensive. Divided into four parts covering Patient Care, Imaging Procedures, Data Acquisition and Processing and Physical Principles of Image formation it also includes a glossary and a single MRI Calculations page. The bulk of the book contains questions including some with adequate if not exceptionally clear photographic images.

On its face, this book appears to be helpful. but neophytes might not recognize the errors so I would use care before relying on this source alone.

Definitely one of the reasons I passed the registry test 1st time up. A simple book of questions with multiple choice answers. If you don't understand why the answer is that particular answer you should cross reference with MRI contrast agent in Practice, MIC Crosstrainer or IACI Online to fully understand as these are NOT the exact registry questions, but gives you a good idea of what to expect and what to study. Definitely don't make this your only study resource though as there's a ton of theory and physics on the test that you need to understand not just regurgitate multiple choice answers.

I have now purchased the ad version and the book itself but they both contain the same mistakes. I don't think that anyone proof read the book before it was published. Answers are misnumbered and just plain wrong answers are given. It's not very helpful when you are trying to study for the Small Animals MRI boards. I have now spent $100 for both and still are looking up the correct answers. Not a review book from these two authors I expected to get.

How do Understand MRI Pulse Sequences

I believe it will become the 'gold standard' text for people involved in MR research or applications because of its clear and concise descriptions of most aspects of MRI.

Magnetic Resonance Imaging (MRI) is among the most important medical imaging techniques available today. There is an installed base of approximately 15,000 MRI scanners worldwide. Each of these scanners is capable of running many different "pulse sequences", which are governed by physics and engineering principles, and implemented by software programs that control the MRI hardware. To utilize an MRI scanner to the fullest extent, a conceptual understanding of its pulse sequences is crucial. This book offers a complete guide that can help the scientists, engineers, clinicians, and technologists in the field of MRI understand and better employ their scanner.

This book is an excellent overview and reference for MRI pulse sequences. It has been recommended to me as a reference by several scientists, and anyone who works in the MRI contrast agent field should consider buying this book -- even if you are not a pulse programmer, this book will give you a much better understanding of different sequences and which one may be most appropriate for your research application. It does a good job of describing sequences in a qualitative as well as mathematical manner.

One slight problem with the book is that it is oriented towards just MRI physics, and thus if one wants to sit down at an actual scanner and try to program or implement the sequence, one might not have enough specific details about hardware-related issues (such as gradient duty cycles, RF power calibration, SAR, memory allocation, etc) to actually implement a sequence. Thus, the book is best supplemented with a review of current literature, as well as manufacturer documentation or examples of previously written pulse sequences.

I got to know this good handbook from an international conference. It was sold out in few days during the exhibition period. I strongly recommend every Bench-top NMR guy own at least one copy of it. ^__^