Contactless Thermometry by MRI and MRS: Advanced Methods for Thermotherapy and Biomaterials

Abstract

Control of temperature variation is of primordial importance in particular areas of biomedicine. In this context, medical treatments such as hyperthermia and cryotherapy, but also the development and use of hydrogel-based biomaterials are of particular concern. To enable accurate temperature measurement without perturbing or even destroying the biological tissue or material to be monitored, contactless thermometry methods are preferred. Among these, the most suitable are based on magnetic resonance imaging and spectroscopy (MRI, MRS). Here, we address the latest developments in this field as well as their current and anticipated practical applications. We highlight recent progress aimed at rendering MR thermometry faster and more reproducible, versatile and sophisticated, and provide our perspective on how these new techniques broaden the range of applications in medical treatments and biomaterial development by enabling insight into finer details of thermal behavior. Thus, these methods facilitate optimization of clinical and industrial heating and cooling protocols.

Label-Free Chemically and Molecularly Selective Magnetic Resonance Imaging

“…In addition to metabolic analysis and imaging applications, MRS can be used for noninvasive molecular characterization and measurement of other physiological conditions in deep tissue and organs, such as temperature . It is worth noting that Robert Gillies, a brilliant cancer biologist and biophysicist who passed away recently, pioneered the use of phosphorus ( 31 P) MRS and pH dependence of chemical shifts of adenosine triphosphate (ATP) to measure the tissue pH and tumor acidity, a hallmark of tumor biology and the tumor microenvironment. , Gillies’ work not only established an innovative early molecular imaging tool but enabled intense and systematic studies that advanced our understanding of the pathophysiological microenvironment of solid tumors and its roles in initiating and promoting malignant clones, genomic plasticity, and heterogeneity in the early development of cancers.…”

Nanomedicines for high‑intensity focused ultrasound cancer treatment and theranostics (Review)

“…Although ultrasound is often utilized as an imaging tool for HIFU theranostics, MRI is considered an improved imaging tool given its non-invasive nature and high spatial and anatomical resolution ( 105 ). Although the majority of HIFU synergists do not have paramagnetic properties that can be seen using an MR scan, certain MR sequences such as MRI thermometry allow for real-time quantification of the local temperature in the tumour tissues ( 106 , 107 ), thus allowing HIFU ablation. Given that magnetic NPs may disrupt the magnetic field when applied for MRI ( 70 ), gold NPs are an alternative for MRI-guided HIFU ablation.…”

Ischemia-Reperfusion Injuries Assessment during Pancreas Preservation

“…Furthermore, in the context of preclinical research, MRI and MRS technology can determine a temperature in a defined deep volume [ 86 ] and allows us to determine pH. Indeed, MRS may measure pH directly with the aid of tracers [ 87 ], in which case careful comparison should be made to the point of neutrality at the relevant temperature.…”