Case 1: imaging pipeline
Differences between high and low grade glioma
Gliomas are a type of brain tumor that originates from glial cells, which are supportive cells
in the brain.
Aggressiveness: They are broadly classified by grade into high-grade gliomas and low-grade
gliomas based on their aggressiveness and potential for growth (divide). Slower-growing
gliomas are also called “low-grade.” These include Grades 1 and 2 gliomas. High-grade
gliomas are Grades 3 and 4. The higher the grade, the more aggressive the brain cancer is.
Cellular Atypia (Cellular Difference): Cells in high-grade gliomas often exhibit significant
cellular atypia, meaning they have abnormal and irregular features. Whereas, cells in low-
grade gliomas are generally more normal-looking compared to high-grade gliomas.
Invasiveness: High-grade gliomas often invade surrounding brain tissue, making complete
surgical removal challenging. While low-grade gliomas can invade nearby tissues and tend to
have a more defined border (clear boundary), making surgical removal comparatively more
feasible/achievable.
Recurrence Rate: High-grade gliomas have a higher likelihood of recurrence after treatment.
Whereas, low-grade Gliomas tend to have a lower recurrence rate.
Main features and differences
Glioblastoma Multiforme (GBM): GBM is a highly aggressive and malignant form of brain
tumor, falling into the category of high-grade gliomas. What sets GBM apart is its distinct
cellular characteristics, as implied by the term "multiforme." Unlike low-grade gliomas, which
generally consist of more uniform and normal-looking cells, GBM exhibits a remarkable
diversity of irregular cell types within the tumor mass. This heterogeneity contributes to the
tumor's aggressiveness, as it can infiltrate surrounding brain tissue extensively. GBM
poses/presents significant challenges in terms of diagnosis and treatment due to its invasive
nature and resistance to conventional therapies. So, GBM is the most common and
aggressive type of high-grade glioma. A low-grade glioma is typically not identified as
glioblastoma, but rather as astrocytoma or oligodendroglioma.
Symptoms: Symptoms in high-grade gliomas may include headaches, seizures, cognitive
decline, and neurological deficits. In low-grade gliomas, symptoms may be less severe
initially and may include seizures or subtle neurological symptoms.
Pathophysiology (stages)
- Pathophysiology is the study of how diseases or abnormalities in the body affect its
normal physiological functions. It involves examining the mechanisms, processes, and
changes that occur within the body as a result of a disease or medical condition. This
field of study seeks to understand the underlying biological and physical alterations
that lead to the signs and symptoms observed in various illnesses. In essence,
pathophysiology provides insight into the dysfunctional aspects of the body during a
disease state, helping healthcare professionals comprehend the basis of disorders
and devise appropriate treatments.
The pathophysiology of gliomas involves a series of stages that highlight the progression and
complexity of these brain tumors. It all begins with genetic mutations in glial cells, triggering
uncontrolled cell growth during the initiation phase. As the disease progresses, these cells
continue to divide, accumulating genetic abnormalities and forming a tumor mass. The
,invasive nature of gliomas becomes evident/obvious as tumor cells infiltrate nearby brain
tissue, posing challenges for complete surgical removal. The tumors further stimulate the
growth of new blood vessels through angiogenesis (growth of blood vessels) to ensure a
nutrient supply in the vascularization stage. Remarkably, gliomas, unlike tumors in other
organs, rarely metastasize outside the central nervous system. The pathophysiological
journey is characterized by genetic and molecular heterogeneity in gliomas, making it
challenging to develop targeted and effective treatments. So there are 6 stages/steps:
initiation, progression, invasion, vascularization, metastasis, and heterogeneity.
Treatment: typically involves a combination of surgery, radiation therapy, and chemotherapy.
High-grade gliomas may require more aggressive treatment due to their propensity for
recurrence.
What is the regular therapeutic plan for a patient diagnosed with glioma?
The therapeutic plan for a patient diagnosed with glioma depends on several factors,
including the type and grade of the glioma, its location, the patient's overall health, and
individualized considerations. Generally, a comprehensive approach involving multiple
treatment modalities is employed:
- Surgery: Whenever feasible,surgical removal of the tumor is attempted. However,
complete removal might be challenging, especially for high-grade gliomas that tend
to infiltrate surrounding brain tissue.
- Radiation Therapy: Radiation therapy is often used after surgery to target any
remaining tumor cells and reduce the risk of recurrence. It may also be the primary
treatment for inoperable tumors.
- Chemotherapy: Chemotherapy, either oral or intravenous, is commonly used to treat
gliomas. It may be administered in combination with radiation therapy or as part of
adjuvant (aiding/assisting) therapy after surgery.
- Targeted Therapy: Some gliomas may have specific molecular characteristics that
make them susceptible to targeted therapies. These drugs aim to interfere with
specific molecules involved in tumor growth.
- Immunotherapy: Immunotherapy is an emerging area of research for gliomas. It
involves boosting the body's immune system to recognize and attack cancer cells.
Clinical trials are ongoing to assess the effectiveness of immunotherapeutic
approaches.
- Clinical Trials: Participation in clinical trials may be considered, especially for patients
with recurrent or advanced gliomas. These trials evaluate new treatments and
therapeutic strategies.
- Supportive Care: Supportive care, including symptom management, pain control, and
psychological support, is an integral part of glioma treatment. It helps improve the
patient's quality of life during and after treatment.
- Follow-up Monitoring: Regular follow-up visits with healthcare providers are
essential to monitor the response to treatment, manage any side effects, and detect
any signs of tumor recurrence early.-11C-methionine tracer-What is it?
The 11C-methionine tracer
The 11C-methionine tracer is a radiolabeled form of the amino acid methionine, where the
carbon-11 isotope is used as a radioactive tag. This tracer is commonly used in medical
imaging techniques such as positron emission tomography (PET).
, Use of 11C-metionine tracer
Cancer Imaging: 11C-methionine PET is used in cancer imaging, particularly in the evaluation
of brain tumors and certain types of cancer.
Brain Tumor Imaging: In the context of gliomas and other brain tumors, 11C-methionine PET
is employed to visualize and characterize the metabolic activity of the tumors.
How is it involved in glioma?
Increased Uptake in Gliomas: Glioma cells often exhibit increased amino acid metabolism,
including methionine. The 11C-methionine PET tracer takes advantage of this metabolic
feature.
Tumor Localization: The tracer accumulates at higher concentrations in areas with active
tumor growth, allowing for the identification and localization of gliomas.
Diagnostic Aid: 11C-methionine PET can aid in the diagnosis and grading of gliomas by
providing valuable information about the extent and metabolic activity of the tumor.
Treatment Planning: It is also used in treatment planning, helping clinicians determine the
boundaries of the tumor and areas with increased metabolic activity that may require
targeted treatment.
Monitoring Response to Therapy: Serial 11C-methionine PET scans may be used to monitor
the response of gliomas to treatment, helping healthcare professionals assess the
effectiveness of therapies over time.
Non-invasive techniques
Magnetic Resonance Imaging (MRI)
Mechanism: Uses magnetic fields and radio waves to create detailed images.
Strengths:
- Excellent soft tissue contrast.
- Multi-parametric imaging capabilities (T1, T2, FLAIR, etc.).
- No ionizing radiation.
Weaknesses:
- Limited sensitivity for certain glioma types.
- Specificity challenges in distinguishing tumor types.
Glioma Coupling: Excellent for visualizing glioma location, size, and extent due to its superb
soft tissue contrast. Limited in distinguishing certain glioma types.
Computed Tomography (CT)
Mechanism: Utilizes X-rays to generate cross-sectional images.
Strengths:
- Fast imaging.
- Broad availability.
Weaknesses:
- Ionizing radiation exposure.
- Limited soft tissue contrast compared to MRI.
Glioma Coupling: Provides quick anatomical information but lacks the detailed soft tissue
contrast of MRI. Frequently used for initial assessment and localization.
