The Critical Role of Imaging in Brain Tumor Diagnosis and Treatment

Imaging plays a pivotal role in diagnosing, treating, and monitoring brain tumors. Two main imaging techniques, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI), are frequently employed in this process. However, it”s important to note that while imaging provides essential insights, a definitive diagnosis necessitates molecular and histopathological analysis obtained through surgical procedures.

CT and MRI Scans

CT scans utilize X-ray beams to generate detailed cross-sectional images, offering quick assessments of brain structures. Conversely, MRI scans employ magnetic fields and radio waves to produce high-resolution images without emitting ionizing radiation, making them safer and ideal for recurrent use.

Purpose of Scans

CT and MRI scans are indispensable tools for identifying tumor presence, size, and specific characteristics. They are instrumental in diagnosis, treatment planning, and monitoring disease progression.

Differences between CT and MRI

While CT scans offer rapid imaging of bones, blood vessels, and soft tissues, MRI scans provide superior soft tissue contrast without radiation exposure. Despite their longer duration and confinement within the machine, MRI scans are preferred for their safety and enhanced visualization.

You will likely only have a CT:

  1. if you end up at the Emergency Department for some reason and they need to do a quick check on your brain and
  2. when your surgery is being planned to help plan and guide your surgery.

MRI is safer and can capture really detailed features of the brain, so it will be used much more frequently throughout the brain cancer patient care pathway. MRI will be used to help diagnose and monitor any changes that happen over time and throughout treatments.

The amount of time in between scans will depend on how aggressive the tumor. More aggressive ones need to be monitored more closely.

What features do physicians look for on images?

  • Irregular Tumor Margins

Irregular tumor margins suggest uneven boundaries between the tumor and surrounding healthy tissue, which can indicate an aggressive growth pattern or a response to treatment.When the edges of the tumor look uneven or irregular, it might mean that the tumor is growing quickly or reacting to treatment.

  • Central Necrosis

Central necrosis refers to dead tissue in the center of the tumor. It”s a common feature seen in aggressive tumors, but it can also occur in tumors that are responding to treatment.Dead tissue in the middle of the tumor is often a sign of aggressive tumors. However, it can also happen when the treatment is working to kill the tumor cells.

  • Contrast Enhancement

Contrast enhancement occurs when the tumor appears brighter after a contrast dye is injected. This brightness indicates that the tumor has the potential to grow quickly. This information helps doctors decide on the best treatment. After a special dye is injected, if the tumor looks brighter on the scan, it means it might be growing faster. This helps doctors decide how to treat it.

  • Vasogenic Edema

Vasogenic edema refers to swelling around the tumor caused by fluid leakage. This swelling can put pressure on the surrounding brain tissue, leading to symptoms. Swelling around the tumor because of fluid leakage can squeeze nearby brain tissue, causing symptoms.

  • Location and Size of the Tumor

The location and size of the tumor are crucial factors in treatment planning and prognosis, as they determine the potential impact on brain function and the difficulty of surgical removal. Where the tumor is in the brain and how big it is are important for planning treatment and predicting how well the patient might do.

Advanced MRI Techniques

  • Diffusion-Weighted Imaging (DWI): DWI checks how water moves in the brain. If there”s a lot of tumor cells or damage, water might not move well. DWI helps detect areas of restricted water movement, which can indicate dense tumor cells or tissue damage, such as in strokes.
  • Perfusion Imaging: Perfusion imaging evaluates the blood flow within the tumor, which can be higher in more aggressive tumors. This technique is particularly useful when monitoring a tumor”s response to treatment, as changes in blood flow can indicate whether the tumor is responding or progressing. When undergoing this type of scan, it is important that the contrast dye is administered at a specific rate, so an autoinjector is used
  • Spectroscopy : Spectroscopy analyzes the chemical composition of a specific brain region, which can help differentiate between a tumor and other brain abnormalities when the imaging findings are unclear.

Pathological Examination

  • Biopsy or Surgical Specimen : A biopsy or surgical removal of the tumor tissue allows for a detailed microscopic examination and molecular testing to confirm the diagnosis and guide treatment. You may sometimes hear the term “needle biopsy”, which is a less invasive procedure to sample the tumor tissue. Histopathological features, such as cellular atypia, mitotic activity, microvascular proliferation, and necrosis, can provide information about the tumor”s aggressiveness and growth patterns. These are determined by the pathologist who will look at the tumor under the microscope. This may take several days for the final results to come back.
  • Molecular Markers: These are additional tests done on the tumor which help determine the tumor type and predict its response to treatment more precisely. Not all hospitals do these tests locally and they may need to send the sample elsewhere; therefore, these tests may take a bit longer to come back. The results we look for today in gliomas include: IDH status, MGMT promoter methylation, 1p/19q co-deletion, TERT promoter mutation, EGFR status, CKDN2A mutation, among others.

Understanding the Results

Combining Imaging and Pathological Findings: The integration of imaging and pathological findings is crucial for accurate diagnosis, tumor classification, and treatment planning for glioblastoma.

Implications for Treatment: Certain imaging and pathological features, such as high mitotic activity or microvascular proliferation, can indicate a more aggressive tumor and influence the choice of treatment. Molecular testing results also have a large impact on the diagnosis and how the tumor is treated.

Prognosis

  • Factors like tumour size, growth rate, and molecular characteristics can provide insights into the expected course of the disease and patient survival.
  • The success of the surgical resection and the amount of tumor removed can also significantly impact prognosis.
  • IDH mutation and MGMT promoter methylation are highly associated with better prognosis and response to standard chemotherapy.

Monitoring and Follow-up

  • Regular MRI scans are used to monitor the response to treatment and detect any signs of tumor progression or recurrence.
  • Changes in the size or enhancement patterns of the tumor on post-treatment scans can indicate how well the treatment is working.
  • Sometimes the changes cannot definitively be attributed to tumor growth versus response to treatment. A multi-disciplinary tumor board discussion among your doctors may be necessary.

Patient Communication

  • Healthcare providers should clearly explain the test results to patients, addressing any concerns or questions they may have.
  • The discussion of test results should include an overview of available treatment options and the patient”s overall health status.
  • Make sure your doctor(s) is part of a multi-disciplinary team of specialists to make sure you are benefiting from the opinion of all specialists.

Disclaimer: The content of this article, including but not limited to text, graphics, images, and other material, is for informational purposes only and is not intended to be a comprehensive guide or a substitute for professional medical advice, diagnosis, or treatment. While the information is based on current research and clinical trials relevant to the topic as of the date of publication, readers should note that medical research is continuously evolving. WeTrials does not guarantee the accuracy or completeness of any information provided and is not responsible for any errors or omissions, or for results obtained from the use of this information. Readers are encouraged to consult a healthcare professional with any questions regarding their health or medical conditions. This disclaimer also serves to remind readers that without consulting with a healthcare provider, they should not make any medication or treatment changes based on the information presented in this article.

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