Proton MR Spectroscopy in Assessing the Biochemical Milieu of Human Testes

Abstract

Proton magnetic resonance spectroscopy (MRS), considered a connection between metabolism and anatomic and functional information provided by standard MRI, gives information on various tissue metabolites and their pathologic changes. Recently, proton MRS has been added as an adjunct tool to the multiparametric protocol of scrotal MRI, providing a new insight into the extremely complex biochemical milieu of normal and abnormal testes. This article reviews proton MR spectra of normal testes, showing age and bilateralism dependence. Disturbances of various metabolic pathways in testes of infertile men resulting in alterations of metabolite peaks are discussed. Preliminary data on proton MR spectra of testicular mass lesions are presented. Level of Evidence: 5. Technical Efficacy Stage: 5.

Visualization of Spatial Distribution of Spermatogenesis in Mouse Testes Using Creatine Chemical Exchange Saturation Transfer Imaging

“…When managing male infertility, the noninvasive evaluation of spermatogenesis is important to determine the optimal treatment strategy. There are several noninvasive markers to evaluate spermatogenesis, including testicular size, serum levels of follicle‐stimulating hormone, genetic testing and testicular metabolite concentrations measured by 1 H MRS 5–7 . These markers, however, exhibit limited predictive value 28 and no methods have been used in clinical settings to noninvasively evaluate the detailed distribution of spermatogenesis within a single testis.…”

“…When managing male infertility, the noninvasive evaluation of spermatogenesis is important to determine the optimal treatment strategy. There are several noninvasive markers to evaluate spermatogenesis, including testicular size, serum levels of follicle-stimulating hormone, genetic testing and testicular metabolite concentrations measured by 1 H MRS. [5][6][7] These markers, however, exhibit limited predictive value 28 and no methods have been used in clinical settings to noninvasively evaluate the detailed distribution of spermatogenesis within a single testis. Notably, CrCEST imaging is capable of evaluating the spatial distribution of spermatozoa in mouse testes, and we believe that this technique may also be useful Johnsen's score for unshielded regions was significantly lower than that for shielded regions (shielded, 7.8 AE 1.2; unshielded, 5.3 AE 2.7; P < 0.0001).…”

“…However, 1 H MRS has not been widely applied in clinical settings due to its technical limitations. The low sensitivity and spatial resolution of 1 H MRS limit the detailed quantification of testicular Cr concentrations and their distribution 5,9 …”

“…The low sensitivity and spatial resolution of 1 H MRS limit the detailed quantification of testicular Cr concentrations and their distribution. 5,9 Chemical exchange saturation transfer (CEST) imaging can evaluate metabolites with exchangeable protons such as amide and amine protons by using prolonged, selective saturation pulses. [10][11][12][13][14][15] CEST imaging that specifically targets Cr amine protons is known as CrCEST imaging, and it has been applied in human muscle and brain.…”

“…Proton magnetic resonance spectroscopy ( 1 H MRS) is a technique for evaluating low-concentration metabolites based on differences in magnetic resonance frequencies. [5][6][7][8] The testicular creatine (Cr) concentration, measured by 1 H MRS, is reported to be decreased in infertile testes and is expected to be a useful biomarker of spermatogenesis. [5][6][7] However, 1 H MRS has not been widely applied in clinical settings due to its technical limitations.…”