Accelerated echo planar J-resolved spectroscopic imaging in prostate cancer: a pilot validation of non-linear reconstruction using total variation and maximum entropy.
The overlap of metabolites is a major limitation in one-dimensional (1D) spectral-based single-voxel MRS and multivoxel-based MRSI. By combining echo planar spectroscopic imaging (EPSI) with a two-dimensional (2D) J-resolved spectroscopic (JPRESS) sequence, 2D spectra can be recorded in multiple locations in a single slice of prostate using four-dimensional (4D) echo planar J-resolved spectroscopic imaging (EP-JRESI). The goal of the present work was to validate two different non-linear reconstruction methods independently using compressed sensing-based 4D EP-JRESI in prostate cancer (PCa): maximum entropy (MaxEnt) and total variation (TV). Twenty-two patients with PCa with a mean age of 63.8 years (range, 46-79 years) were investigated in this study. A 4D non-uniformly undersampled (NUS) EP-JRESI sequence was implemented on a Siemens 3-T MRI scanner. The NUS data were reconstructed using two non-linear reconstruction methods, namely MaxEnt and TV. Using both TV and MaxEnt reconstruction methods, the following observations were made in cancerous compared with non-cancerous locations: (i) higher mean (choline + creatine)/citrate metabolite ratios; (ii) increased levels of (choline + creatine)/spermine and (choline + creatine)/myo-inositol; and (iii) decreased levels of (choline + creatine)/(glutamine + glutamate). We have shown that it is possible to accelerate the 4D EP-JRESI sequence by four times and that the data can be reliably reconstructed using the TV and MaxEnt methods. The total acquisition duration was less than 13 min and we were able to detect and quantify several metabolites.
Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
Rajakumar
R
Nagarajan
Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
Zohaib
Z
Iqbal
Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
Brian
B
Burns
Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
Neil E
NE
Wilson
Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
Manoj K
MK
Sarma
Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
Daniel A
DA
Margolis
Urology, University of California Los Angeles, Los Angeles, CA, USA.
Robert E
RE
Reiter
Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
Steven S
SS
Raman
Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
M Albert
MA
Thomas
D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D017352:Echo-Planar Imaging / Q000379:methods*; D019277:Entropy; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D010865:Pilot Projects; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D014408:Biomarkers, Tumor
4D EP-JRESI; Glx; MRS; citrate; echo planar spectroscopic imaging; myo-inositol; prostate cancer