Communicating the Doubts to my External Guide

11:07 pm

1) What is the expected input to the project?

2) What is the expected output from the project?

3) The problems with the solution to the data acquisition problem. solution?

4) My suggestion : ASP inverse problem

5) advantages, and paper to be referred.

Don't have an idea about how the conversation regarding first 2 questions will go, but here's my argument to defend my proposal.

3) Are we looking at real life scale replication model of the umbilical or middle cerebral artery flow? 

If so, according to this paper the mean umbilical artery diameter is always less than or equal to 4 mm, and according to this paper mean middle cerebral artery diameter is 0.83 mm around the 32nd gestational week when we usually do the Umbilical Artery or the Middle Cerebral Artery Ultrasound. The most feasible diameter is then Umbilical artery, 4 mm diameter pipe.

According to this, a pulsatile flow pump and a ultrasonic doppler flow meter should be available. According to this catalog the, the flowmeter can support a syringe of a minimum of 177.8 mm. Is it the right paper I should be looking at? I've got no idea. My external guide didn't mention anything about the pump. All he talked about was the the ultrasound doppler flowmeter.

Thus, according to these specifications the ultrasound doppler flowmeter supports pipe with the diameter of minimum 20 mm.

----> So we see that, real life scale replication of even the Umbilical Artery isn't possible!

Thus if we have to do this, we have change the scale of everything. Doesn't that invalidate the entire motive? Solution?

4) Even if the above argument is not convincing enough, I feel the need to propose another model which can simulate the fetal-Placental artery system.

This is a computer simulation based on Inverse Modelling. In inverse modeling, the model is a black box with unknown characteristic values. Given a set of outputs, the task is to identify these unknown characteristic values that produce outputs that match the given output to complete the model.
In our case the simulation output is the velocity profile of the blood or the blood flow. The inversion task is to identify the corresponding parameter values in the fetal-placental artery system to produce that blood flow.

Also, in our case, what affects the fetal-placental blood flow is :
i)   the values of the fetal heart rate,
ii)  the placental resistance
iii) the brain resistances

Based on the information, we can analyze the correlation between fetal heart rate and blood flow in the compensatory fetus.

Now, how do we find these characteristic values? We use the Genetic Algorithm. Genetic algorithm mimics the process of evolution. This is as follows :
i)   Start with a population of randomly generated individuals,
ii)  Find the fitness of all the individuals in this generation,
iii) Select multiple, say 2 individuals from this population with highest level of fitness
iv) Mutate them to form the next generation
v)  Repeat the process till satisfactory level of fitness has been reached.

Applying this to our case, the each characteristic represents the individual in the generation, then we define the fitness level, in terms of how close the values of the simulated output should be to the expected output. And thus we implement the algorithm using various techniques of mutation, or crossover, and repeat the process till the fitness level is reached.

The black box then represents our system.

This has been implemented before, and I have this paper (please refresh to download or view) for help. Additionally, the entire theory is easily available for study. And trustworthy.

Once we have established the characteristics of the system to get certain output, we can give it various input to generate fetal-placental flow with various conditions. This can become the input to another signal processing system which will classify it, and determine which condition exists. This will validate our signal processing system.

Ya? ATB!

Admitting the Doubt in Feasibility

10:20 am

So, The following are the points at which I'm feeling I have doubts.

1) Simulating the flow: We could used Adaptive signal processing techniques to create the same output that the placenta creates, from Gaussian noise. This paper helps us do that. Gotto study this paper as an alternative to the unnecessary extensive mechanical work on fluidics. But I'm guessing my external guide doesn't trust the signal processing techniques very much, so, I will have to be thorough with the paper before I even suggest him with this alternative. ATB!

2) Diameter of the pipe: The pipe that emulates the umbilical artery must be around 1.5 to 2 mm in diameter, whereas the one that emulates the middle cerebral can be around 3.5 mm in diameter, according to information I found on Google. Thus, based on the size constraints, emulating the middle cerebral artery is the better solution of the two. But that still is very small a size to simulate a pulsatile flow in.

3) Pulsatile flow pump: The only one pump that I found on the net was this. I'm not sure if this is the right one. Because this one is not for research purposes, it looks like it is for industrial, I mean practical use by the doctors during surgeries or so. Other articles I found were all papers which showed how to create a computer controlled flow pumps for pulsatile flow simulations. Asking my internal guide, then the HOD, and then the action plan decision is the agenda for next week.

4) Doppler / Ultrasound Flowmeter: In addition to giving me a tension that it is not audio that we are taking in as the imput, this also gives me a tension about are these available in the labs and are they available in the size of 3.5 mm? This Ultrasonic flowmeter manual suggests otherwise!

Overall, I'm still amazed at the minute feasibility percentage that I'm relying upon, and continuing with this project!

ATB!

No Go with a Confused Head

10:46 am

What did start out with ? What am I doing? What will this take me to? 

My Project Title as I have submitted to the Goa University is "Analysis of audio output of Ultrasound Doppler for Diagnostic Applications using Signal Processing Techniques". Now, I'll just try to breakdown the title and see if I see all of those things being accomplished in sight. I'll start with, 

Signal Processing Techniques : Yes, as far as I can see, I'll have to do this by myself, no problem, but looks like that's the only part that is going to be actually related to my branch of communication. Now what is the input to this signal processing system, and what is its expected output?

Expected input: Audio signal from patient

Problem: Too many variants, needs detailed observation, might lose focus on necessary data in trying to maintain stable conditions to take observations in.

Solution: Simulate the blood flow and measure the data. Thus stable and known operating conditions and flow, open for verification.

Problem: The output from the simulated system isn't audio, instead, it is the velocity of flow.

Need solution for this!

Expected output: A classification eg, normal, abnormal, or output giving specific condition. It is plane useless if the output gives a velocity profile. Because that an ultrasound machine can do!

Here's what I'm thinking pictorially : 

The Expect Project Flow :

The Actual Project Flow that it has turned out to be :

What I need is a block that will bridge the gap between these two different input blocks, which looks something like this : 

This is a very very important paper which lets me add that second block, and it's the only only solution to the problem in sight to me! Otherwise, just gotta follow what my External Guide says!

A Promising Discussion with my External Guide and Some Concerns

12:35 pm

Yesterday, my External Guide replied to the mail I had sent him, stating the problems that I'm having primarily based on Data Acquisition. In his reply, he wished to have a discussion regarding the project over the telephone.

In the discussion, we spoke about the following:

1. Problems with Data Acquisition directly from the patient

2. Solution to the problem using laboratory simulations of the patient.

3. An outline of the laboratory procedure

4. Availability of the necessary Laboratory Equipment

5. Planned timeline

Problems with Data Acquisition directly from the patient 

• If we collect data from an ultrasound machine from patients, there are a lot of variables. The patients could be having various types of diseases. Analysis would be influenced by the disease conditions that the patients have. Thus, validation of signal processing will become very tough. Anyone could challenge the reliability on the outcome of the processed signal. 

• Also, it is very common that, in a patient, during observation, a blood vessel suddenly changes its diameter or the baby itself moves within the within the womb, as a result of which getting steady readings is highly impossible. Also, the velocities the doctors get in the morning are completely different from what they get in the evening. Many a times readings diagnosed as abnormal in the morning, may be normal in the evening with the same patient. So, taking steady readings requires a very detailed kind of an examination, on patients. 

• Also limited by, regulatory requirements of taking patient's consent, unnecessarily delay. 

• Analysis would be influenced also by the amount of data we collect. 

• Before going to the patients , it is always a good idea to do the lab test. 

• In the lab we can have simulated conditions, and thus, actually compare the signal processing techniques with a simulated flow that we simulate. Therefore you will have a greater confidence in saying that the applied processing techniques, and the results that are being obtained from those techniques, are actually matching. This becomes the proof. 

• Additionally, there are many other parameters which are not being measured in a doppler study. For example Doppler signal is a map of fluid velocities at different times. As the fluid velocities change, the doppler signal also changes. But, it is very difficult to analyse, from just knowing the fluid velocities, what the pressure changes are present in the vessels, due to which the fluid velocities change. But if we have a simulated flow, then you can actually measure them.

• Then we will be able to arrive at some kind of a relation, between the doppler signal and pressure measurement or the pressure distance between different of the pipe which is emulating the artery. 

• In this way, if we can identify more parameters than just the flows, using the flow signal itself then we can extrapolate the knowledge of changing flows, and map the causes to probably the pressure difference, may be the vascular resistance, or may be the diameter of the vessel or suddenly changes. 

• This is the reason why we decide to keep the patient studies for a later stage in the project. 

An Outline of the Laboratory Procedure 

• We need to collect some form of a data of flowing fluid, analyze that data, and from that data analysis we are trying to characterize, the flow.

• Thus, we need a laboratory set up, where you can actually have flowing fluid. To collect or read the data we’ll need an ultrasound, or a doppler flowmeter. 

• To emulate the flow in a lab, we need to make the setup in such a way, that, it resembles the actual physiological pulsatile flow in an artery. We can have various physiological scenarios that we could simulate on such a model, and thus the working conditions would be in our control, that is, we’ll have a control environment. 

• We could change the scenarios based on different values of flow rates, pressure differences between the two ends of the pipe, and pulsatile magnitude. 

• Now, if we acquire the signal using the flowmeter, and apply the signal processing techniques, we can actually validate your technique, because, we are having a control environment. 

• This would give us a very good understanding of the flows within the vessels and so on. 

• Thus, this point can become a very good validation point. and we can always very well defend a thesis that we can validate. 

The Availability of Necessary Laboratory Equipment 

• We could design the experiment and the setup necessary, but the equipment required has to be available. 

• Also, it becomes altogether simpler if the particular laboratory technician is able to help out with setting up of the experiment. 

• The second chapter of the thesis should be on these you know setting up the lab simulating lab. eg, is it the umbilical artery flow that we are trying to simulate or the middle cerebral artery flow? Accordingly the pulsatality could be kept at 72 beats per minute or 140 beats per minute. As such, what all are the configurations possible? etc. 

• Need a flowmeter which will suffice to our conditions, so need to select a flowmeter with a suitable specification. 

• We need to prove it that the the experimental setup, is the best possible that we could have for the specified simulation conditions. 

Planned Timeline 

• The Data Acquisition stage normally takes around 2 months. 

• In the 3rd month, may be by December, we should be able to acquire the data and perform the first set of simulated experiments. 

My concerns:

1. Do we have the facilities available here in Goa College of Engineering? Like in the departments eg, Mechanical department..? Or will I have to go to IIT Bombay? Is that possible?

2. Does the project still remain based on audio Doppler,.. since that is included in the name of the project.