PET-CT A Tool To Diagnose Inflammation
Posted By HealthcareOnTime Team
Posted on 2022-02-10
Inflammation is defined as a protective response
generated by our body at the site of an injury or a
tissue which has undergone destruction. This
response aids to either destroy or dilute the
invaders or create a wall between the injured
tissue and the injurious agent.
An injurious agent can be any pathogen, a dust particle,
pollen grain, or any food constituent, etc. These foreign
antigens can enter the body through mouth, while
breathing, through a wound, through insect bite, etc.
Our body exhibits inflammation in various ways; the
most common ones include pain, swelling, and redness
of the skin. The extreme form of inflammation includes
the loss of functions by the affected organ. Although
an inflammatory response is instigated by an infection,
it is a result of attack by our body to the infection so
as to get rid of it. The inflammatory response is purely
ruled by fighter cells of our body, i.e. the white blood
cells and more specifically the neutrophils. This
response is a component of innate immunity wherein
the neutrophils are directed towards the site of infection,
then these neutrophils generate a cascade of chemical
reactions which aid in the removal of the pathogen.
Inflammation is classified into two types viz. acute
inflammation, which is an outcome of the initial
inflammatory response where movement of the
plasma and neutrophils at the site of injury occurs,
followed by various biochemical reactions. Type two
being, chronic inflammation wherein the inflammation
prolongs and the neutrophils present at the site of
inflammation are replaced by the macrophages &
the lymphocytes. An acute inflammation is
characterized by pain, swelling, redness, etc.
at the site of inflammation, while a chronic
inflammation is mostly found to arise either
from a prolonged infection or due to an
inappropriate response of the immune system
which leads to autoimmune diseases.
PET-CT a tool to diagnose inflammation
PET-CT (Positron emission tomographycomputed tomography)
is a technique which combines the functional information from
the PET scan with the structural information obtained from CT
scan. FDG-PET (Fludeoxyglucose PET) combined with CT scan
has proved to be a powerful imaging technique in the field of
cancer diagnosis. Besides cancer diagnosis, FDG-PET/CT has
also gained importance in diagnosis of inflammatory diseases
and for monitoring therapies in particular. There has been
enough study on the use of FDG-PET/CT in diagnosis,
management and follow-up in patients suffering from
inflammatory diseases like, sarcoidosis, spondylodiscitis
and vasculitis. FDG-PET/CT has also been used in diagnosis
of other inflammatory diseases like, rheumatoid arthritis,
autoimmune pancreatitis and Inflammatory Bowel Diseases.
It is an inflammatory disorder, characterized by collection
of abnormal chronic inflammatory cells in different organs
of the body, leading to formation of nodules. The potential
cause of sarcoidosis is not confirmed; however, one or more
infectious agents could be the potential cause of sarcoidosis.
Since sarcoidosis is a multisystem granulomatous disorder,
its diagnosis cannot be specific. The diagnosis of sarcoidosis
using PET-CT proves useful in selection of the biopsy sites by
enabling a proper identification of the affected organ. FDG
activity is largely observed in the lymph nodes and the
pulmonary parenchyma where there is an inflammation.
Inflammation of one or more intervertebral disc spaces
and vertebrae adjacent to the intervertebral spaces
results into Spondylodiscitis. The main causative
agents of spondylodiscitis are Staphylococci and
Mycobacterium tuberculosis and the disease mainly
develops in individuals who are immunocompromised.
PET-CT is found to be highly sensitive in diagnosis of
spondylodiscitis and also differentiates the disc infection.
PET-CT is also efficient in monitoring the therapeutic
response in patients suffering from spondylodiscitis.
Vasculitis is characterized by the destruction of arteries
and/or veins due to inflammation, primarily caused due
to migration of the WBCS. PET-CT has proved to be
useful for the diagnosis of vasculitis in patients with
non-specific symptoms. It also aids in identification
of areas with an increased FDG uptake so that a biopsy
can be done. PETCT also helps in evaluating the extent
to which the disease is caused and also the response of
the patient towards the treatment.
Rheumatoid arthritis is a systemic autoimmune inflammatory
disorder that mainly affects the joints. PETCT is used for
evaluation of the activities of the disease, the sites where
the disease is found and the response of the treatment
towards rheumatoid arthritis. The FDG molecules used
for diagnosis purpose in PET-CT show high activity in
synovium (connective tissue of joints) of the affected joints.
It is a type of chronic pancreatitis which is characterized by
inflammation of the pancreas. Autoimmune pancreatitis is
not quite distinguishable from pancreatic carcinoma (PC).
PET-CT aids in differentiating autoimmune pancreatitis
from pancreatic cancer. This is achieved by assessing
the pattern of FDG uptake in the pancreas and the extra
pancreatic lesions. PETCT also has the potential to assess
the disease activity of autoimmune pancreatitis and that
of extra pancreatic lesions.
Inflammatory bowel disease
Inflammatory bowel disease is an autoimmune disease
which is characterized by the inflammation of the colon
and the small intestine. The major types of inflammatory
bowel diseases are Crohn's disease (inflammation of any
part of the gastrointestinal tract) and ulcerative colitis
(inflammation of the colon). PET-CT is used to efficiently
diagnose different types of inflammatory bowel diseases.
Technology has grown, so has the need. It is time our
smart world takes advantage of it!