Multiplet resonances in MRS data from normal and cancerous prostate - Signal Processing in MRS with Biomedical Applications - page 338

precursors and degradation products of membrane phospholipids. They note
that tumors with higher metastatic potential have higher bulk membrane
rigidity with higher cholesterol and lower phospholipid. They also note that
the peripheral zone is the site of 68% of prostate tumors and that region has an
elevated citrate concentration. Citrate concentrations in the transition zone
can increase with BPH if there is a high glandular fraction, and can decrease
if the region of BPH has a high stromal content. With prostate cancer, the
decreased glandular fraction can lead to decreased citrate concentration.
Further insights have subsequently been gleaned into the components of
total choline with respect to prostate cancer. Significantly higher phospho
choline and glycerophosphocholine levels have been found in human prostate
cells derived from metastases compared to normal prostate epithelial and stro
mal cells [310]. It is concluded: “the elevation of the choline peak observed
clinically in prostate cancer is attributable to an alteration of phospholipid
metabolism and not simply to increased cell density, doubling time or other
nonspecific effects” (p. 3599) [310].
Through HRMAS, Swanson et al. [442] assessed 54 postsurgical prostate
samples obtained using MRI plus threedimensional MRSI. Presurgical MRI
plus MRSI identified healthy and cancerous prostate tissues with 81% ac
curacy. Healthy glandular tissue was distinguished from prostate cancer by
significantly higher levels of citrate and polyamines, and lower choline, phos
phocholine and glycerophosphocholine. Predominantly stromal tissue lacked
citrate and polyamines, but had significantly lower levels of choline compounds
compared to malignant tissue. Taurine, myoinositol and scylloinositol as well
as choline compounds were higher in prostate cancer. More aggressive can
cers showed higher choline and lower citrate and polyamines. The authors
conclude: “the elucidation of spectral patterns associated with mixtures of
different prostate tissue types and cancer grades, and the inclusion of new
metabolic markers for prostate cancer may significantly improve the clinical
interpretation of in vivo prostate MRSI data” (p. 944).
More recently, Swanson et al. [443] reported metabolite concentrations from
sixty postsurgical samples of healthy glandular and stromal prostate tissue
as well as prostate cancer using HRMAS. The malignant prostate samples
were significantly distinguished from both these normal tissues by higher con
centrations of lactate (1.34 ppm and 4.14 ppm), phosphocholine (3.23 ppm)
plus glycerophosphocholine (3.24 ppm), as well as by total choline. However,
it was only in comparison to healthy glandular tissue, that prostate cancer
differed significantly with respect to lower citrate (2.54 ppm and 2.72 ppm)
and polyamines (3.10 ppm and 3.14 ppm). On the other hand, the prostate
cancer specimens had significantly higher alanine (1.49 ppm, 2.54 ppm, 2.72
ppm) and choline (3.21 ppm) concentrations than the healthy stromal tissue,
but these concentrations differed only at a borderline level of significance for
healthy glandular tissue versus prostate cancers.
The cited concentrations were computed using LorentzianGaussian peak
fitting within the LevenbergMarquardt algorithm.

These authors [443] re