Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical and magnetic resonance imaging approaches for investigating the
  tumour microenvironment: state-of-the-art review and future trends   The tumour microenvironment (TME) strongly influences tumorigenesis and
metastasis. Two of the most characterized properties of the TME are acidosis
and hypoxia, both of which are considered hallmarks of tumours as well as
critical factors in response to anticancer treatments. Currently, various
imaging approaches exist to measure acidosis and hypoxia in the TME, including
magnetic resonance imaging (MRI), positron emission tomography and optical
imaging. In this review, we will focus on the latest fluorescent-based methods
for optical sensing of cell metabolism and MRI as diagnostic imaging tools
applied both in vitro and in vivo. The primary emphasis will be on describing
the current and future uses of systems that can measure intra- and
extra-cellular pH and oxygen changes at high spatial and temporal resolution.
In addition, the suitability of these approaches for mapping tumour
heterogeneity, and assessing response or failure to therapeutics will also be
covered.

17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an