I got an MRI raw data. Now how do I convert it to an MRI image? These are the current steps that I follow : 1. translation of data to R = input[i]*Cos((2*pi*f)*n/N) I = input[i]*Sin((2*pi*f)*n/N) 2. Zero pad the R and I data to reach data size allowable for FFT 3. perform a Horizontal then a Vertical FFT 4. get the absolute value of R and I Unfortunately, all I get is NO Image. Anything I missed here?? also there are parameters that makes no sense to me, sampling rate, AD samples, taps. I understand thet qd points and qd cycle are used for the cosine and sine tables. Thanks Jeff
help : Analyzing MRI raw data
Started by ●November 9, 2003
Reply by ●November 10, 20032003-11-10
It is my understanding that the MRI uses the Radon transform for image projection. Therefor you need the inverse Radon transform. Do a google search on radon transform. There are some good papers there. Maurice Givens "Jefferson O. Siy" <jeffsiy@pacific.net.ph> wrote in message news:<bolr7v$ri2$1@nobel2.pacific.net.sg>...> I got an MRI raw data. Now how do I convert it to an MRI image? > > These are the current steps that I follow : > 1. translation of data to > R = input[i]*Cos((2*pi*f)*n/N) > I = input[i]*Sin((2*pi*f)*n/N) > 2. Zero pad the R and I data to reach data size allowable for FFT > 3. perform a Horizontal then a Vertical FFT > 4. get the absolute value of R and I > > > Unfortunately, all I get is NO Image. > > > Anything I missed here?? > > also there are parameters that makes no sense to me, sampling rate, AD > samples, taps. > I understand thet qd points and qd cycle are used for the cosine and > sine tables. > Thanks > > Jeff
Reply by ●November 14, 20032003-11-14
Thanks for the info Maurice. after a lot of testing...I got the image. it has something to do with the resampling filter that downsamples the data to a size that can be proecessed by FFT. Thanks again Jeff Maurice Givens wrote:> It is my understanding that the MRI uses the Radon transform for image > projection. Therefor you need the inverse Radon transform. Do a > google search on radon transform. There are some good papers there. > > Maurice Givens > > > "Jefferson O. Siy" <jeffsiy@pacific.net.ph> wrote in message news:<bolr7v$ri2$1@nobel2.pacific.net.sg>... > >>I got an MRI raw data. Now how do I convert it to an MRI image? >> >>These are the current steps that I follow : >>1. translation of data to >> R = input[i]*Cos((2*pi*f)*n/N) >> I = input[i]*Sin((2*pi*f)*n/N) >>2. Zero pad the R and I data to reach data size allowable for FFT >>3. perform a Horizontal then a Vertical FFT >>4. get the absolute value of R and I >> >> >>Unfortunately, all I get is NO Image. >> >> >>Anything I missed here?? >> >>also there are parameters that makes no sense to me, sampling rate, AD >>samples, taps. >>I understand thet qd points and qd cycle are used for the cosine and >>sine tables. >>Thanks >> >>Jeff
