Dec 21, 2020
Journal of Magnetic Resonance Imaging
Editorial for “Accurate Estimation of the Duration of Testicular Ischemia Using Creatine Chemical Exchange Saturation Transfer (CrCEST) Imaging” Precise assessment of the ischemic duration and severity of testicular torsion is a prerequisite for judging testicular damage and choosing an accurate treatment method. Clinical presentation collected by physical examination is used as the conventional evaluation procedure. Color Doppler ultrasonography examination is widely used as an imaging technique. Although high sensitivity and specificity are reported in previous studies, the results may be affected by the operator’s level of dexterity and experience. Therefore, medical history and the physical examination result of the patient are required as supplemental information. Magnetic resonance imaging (MRI) is another effective evaluation method. Both diffusion-weighted MRI and contrast-enhanced dynamic MRI combined with diffusion-weighted MRI are reported to be able to detect testicular torsion. However, most of them are single-center estimations, and no objective consistent and reliable system has been established. Chemical exchange saturation transfer (CEST) imaging is a relatively novel MRI protocol. In its imaging, protons or molecules that are contained in exogenous or endogenous compounds and exchangeable with water molecules are first selectively saturated by a radiofrequency (RF) pulse. Then the targeted metabolite concentration is evaluated indirectly by the degree of decline of the water signal. Since the water signal is measured in a traditional MRI sequence, the CEST MRI can provide high spatial resolution and a high sensitivity image. The targeted metabolite can be detected even though it is at millimolar physiological concentrations. Much of the previous research on CEST imaging targeting creatine (Cr) amine protons (CrCEST) were performed with 3T or 7T MRIs, focusing on skeletal muscle, myocardium, and brain. These studies have provided promising data and evidence for the technical feasibility of CrCEST in testis. In this issue, Takahashi et al employed an 11.7T MRI and mouse model in search of an accurate determination of the duration of testicular ischemia. They found that the CrCEST effect was much higher in testes than that in skeletal muscle. There was no significant difference of the CrCEST effect between the two testes of control mice, but the CrCEST effect was significantly lower in ischemic testes than that in controls. A strong linear correlation was also observed between the duration of ischemia and the decline of the CrCEST effect (r = 0.96). This well-designed and carefully executed study reports for the first time the prominent CrCEST effect in mouse testis and reveals a strong correlation between the decrease of the CrCEST effect and the duration of testicular ischemia. These results provide an accurate estimation method of the duration of testicular ischemia. Although multicenter and 3T or 7T MRI studies are necessary to collect supporting data for the current singlecenter animal model study, Takahashi et al have proposed a direction for future research.