|Year : 2019 | Volume
| Issue : 1 | Page : 77-78
Harnessing heat for diagnosis and therapy
Nagraj Gururaj Huilgol
Department of Radiation Oncology, Nanavati Super Speciality Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||22-May-2019|
Dr. Nagraj Gururaj Huilgol
Department of Radiation Oncology, Nanavati Super Speciality Hospital, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
Hyperthermia is an important adjunct to radiation therapy and chemotherapy. Heat includes in cellular organelle, cell membrane and vasculature. The changes can't be measured and imaged using magnetic resonance imaging. Currently, MRI thermometry is available while cellular and structural changes following heat for the purpose of diagnostics and prognostication needs further exploration. MRI- can be developed for theranostics.
Keywords: Magnetic resonance thermometry, neoplasms, Pyrexar
|How to cite this article:|
Huilgol NG. Harnessing heat for diagnosis and therapy. J Radiat Cancer Res 2019;10:77-8
Hyperthermia as a modality of treatment has had a checkered history. The renaissance of hyperthermia witnessed in the eighties soon receded in the background due to competing modalities like chemotherapy. The emergence of noninvasive thermometry with innovations in multiphased array of microwave systems has enhanced the confidence of heat delivery in complex situations. Hyperthermia with radiation and chemotherapy has clawed back in relevance. Online magnetic resonance imaging (MRI) thermal dosimetry as in Pyrexar heating system offers an opportunity beyond therapy.
Measuring temperatures of internal organs, and of tumor, noninvasively using MRI, is novel idea. MR-thermometry is an exciting development of the last decade. Parameters of MRI such as proton density, spin lattice relaxation (T1) spin to spin relaxation (T2), diffusion coefficient magnetisation transfer and proton resonance frequency are temperature dependant. Spectroscopic imaging and temperature based contrast imaging having give information on absolute temperatures in contrast to above mentioned technique. The Duke's approach of MR-thermometry is based on “intermolecular multiple quantum coherence (MQC's), in hydrogen atoms. As Warren put it, “the difference between water and fat is an absolute magnetic resonance thermometer”. This approach overcomes the limitations due to fat. However proton resonance frequency has demonstrated a superiority over other parameters. Linearity and tissue independence makes it reliable measuring tool of temperature. Intermolecular multiple quantum MR thermography is based on detection of water –fat : ZQCS. (intermolecular zero quantum coherence) which produce an absolute temperature map. These are insensitive to distortion unlike one based on proton resonance frequency shift. Spectroscopic imaging and temperature-based contrast imaging have given information on absolute temperatures in contrast to above-mentioned technique. The Duke's approach of MR thermometry is based on “intermolecular multiple quantum coherence, in hydrogen atoms.” As Warren put it, “the difference between water and fat is an absolute MR thermometer.” This approach overcomes the limitations due to fat.
Tissues on heating undergo structural and metabolic changes. Thermal parameters of different tissues vary and so does that of neoplastic mass. Neoplasms, in addition, display unique perfusion patterns due to neoangiogenesis and leaky capillaries. Cancer acts as a heat sink because of which thermal patterns are quite different from normal tissues. Further, thermograms of granuloma and neoplasm may also be quite distinct, thus aiding in the differential diagnosis. Thermograms in conjunction with texture analysis will add value to structural and functional analysis of the tumor. Posthyperthermia spectroscopy will further aid in gleaning information about metabolic status. Thermograms in conjunction with MR mammogram may increase specificity of the investigation. Similarly, MRI thermogram may be predictive in assessing drug response to drugs particularly, for vascular endothelial growth factor inhibitors. Low-flow tumors perhaps will be more amendable to hyperthermia and unresponsive to chemotherapy. MRI thermogram has the potential to enhance diagnostic possibilities as well as predictive of response to various therapeutic modalities such as chemotherapy and radiation. Currently, Pyrexar has the ability to heat simultaneously with online thermometry. Exploration of possibilities of MRI thermometry can be initiated with the existing technology.
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Conflicts of interest
There are no conflicts of interest.