Prebiopsy magnetic resonance spectroscopy and imaging in the diagnosis of prostate cancer

Abstract

Introduction: Existing screening investigations for the diagnosis of early prostate cancer lack specificity, resulting in a high negative biopsy rate. There is increasing interest in the use of various magnetic resonance methods for improving the yield of transrectal ultrasound‐guided biopsies of the prostate in men suspected to have prostate cancer. We review the existing status of such investigations. Methods: A literature search was carried out using the Pubmed database to identify articles related to magnetic resonance methods for diagnosing prostate cancer. References from these articles were also extracted and reviewed. Results: Recent studies have focused on prebiopsy magnetic resonance investigations using conventional magnetic resonance imaging, dynamic contrast enhanced magnetic resonance imaging, diffusion weighted magnetic resonance imaging, magnetization transfer imaging and magnetic resonance spectroscopy of the prostate. This marks a shift from the earlier strategy of carrying out postbiopsy magnetic resonance investigations. Prebiopsy magnetic resonance investigations has been useful in identifying patients who are more likely to have a biopsy positive for malignancy. Conclusions: Prebiopsy magnetic resonance investigations has a potential role in increasing specificity of screening for early prostate cancer. It has a role in the targeting of biopsy sites, avoiding unnecessary biopsies and predicting the outcome of biopsies.

What kind of prostate cancers do we miss on multiparametric magnetic resonance imaging?

“…A multi-parametric MRI (mpMRI) approach is recommended, consisting of morphological T2-weighted imaging (T2-WI) supplemented with at least two functional imaging techniques such as diffusionweighted imaging (DWI), MR spectroscopy (MRSI) or dynamic contrast-enhanced imaging (DCE) [1]. Recent publications report sensitivities, specificities and negative predictive values (NPV) for mpMRI of 71−84 %, 33−70 % and 69− 91 %, respectively, for prostate cancers (PrCa) of any grade, and 80−90 %, 47−61 % and 92−100 %, respectively, for high-grade (HG) PrCa [2][3][4][5][6][7][8][9].…”

“…Although PrCa is the most frequent tumour in men, up to 40 % of tumours will never cause symptoms or death, they are deemed 'clinically insignificant' [3]. MpMRI could be used as an additional parameter to exclude clinically significant PrCa in patients with elevated PSA and consequently to avoid unnecessary biopsy and treatment.…”

Explicit extraction of absorption peak positions, widths and heights using higher order derivatives of total shape spectra by nonparametric processing of time signals as complex damped multi-exponentials

“…However, for reconstruction of the fundamental parameters from the magnitude of the mth derivative spectrum, what matters in the end is their relations to the reference non-derivative (m = 0) absorption lineshape A k (ν). The sought absorptive peak height h k from (35) and h k,m from (52) are related by:…”

“…First, formula (62) tells us that the sought {FWHM} k of the absorption A k (ν) from (15) can be obtained if {FWHM} k,m for the magnitude spectrum is available for a fixed derivative order m. Therefore, from a bell-shaped Lorentzian lineshape g k,m (ν) for the magnitude of the mth derivative spectrum, the three parameters {ζ k , λ k , |d k |} of the absorption A k (ν) in (15) can be extracted from the analytical expressions (35), (53) and (62), or explicitly, in their mentioned "inverse" forms:…”

“…in Refs. [2,26,[33][34][35][36]. Notwithstanding these important achievements, the diagnostic accuracy of MRS and MRSI is still generally insufficient for the stringent requirements of personalized cancer medicine [10,12,37,38].…”