Brain Tumor

Because skull X-rays cannot visualize intracranial tumors, cross-sectional imaging is required. The most commonly used tests are CT and MRI. These are essential not only for initial diagnosis but also for assessing treatment response and surveillance for recurrence.

Computed Tomography (CT)

CT combines X-ray imaging with computer processing. Intravenous contrast may be used to enhance lesion visibility. CT is fast, useful for detecting skull changes and tumor calcifications, and can be performed in patients who cannot undergo MRI (e.g., certain implanted devices, severe claustrophobia). Limitations include lower soft-tissue contrast compared with MRI and primarily 2-D slices.

Magnetic Resonance Imaging (MRI)

MRI uses strong magnetic fields and radiofrequency pulses—not ionizing radiation—to generate high-contrast images of brain tissues. It provides superior soft-tissue detail and multi-planar views, aiding in delineation of tumor extent and relationships to critical structures. Gadolinium-based contrast is typically required for optimal tumor detection and characterization. Advanced MRI techniques—including MR spectroscopy, perfusion imaging, and functional MRI—can assess tumor metabolism, vascularity, and proximity to eloquent cortex, informing diagnosis and surgical planning.

Cerebral Angiography

Catheter-based angiography injects contrast directly into arteries to map cerebral vessels on X-ray. It may be used preoperatively to understand tumor vascular supply and its relation to nearby vessels. Preoperative embolization can be performed in highly vascular tumors to reduce intraoperative bleeding.

PET Imaging

Positron emission tomography (PET) uses radiolabeled tracers to visualize metabolic activity and may assist in diagnosis, grading, or detecting recurrence in selected cases.

Unlike many systemic cancers, primary brain tumors are not typically staged using a standard TNM system because they seldom metastasize outside the central nervous system. Clinically, disease extent is sometimes described as:

• Localized disease: confined to one brain region.
• Intracranial spread: extension across compartments (e.g., supratentorial ↔ infratentorial), across hemispheres, or into meninges/skull.
• Disseminated disease: leptomeningeal spread via cerebrospinal fluid or, rarely, distant metastasis (marrow, lungs, liver).

Surgical Treatment of Brain Tumors

Imaging and surgical advances have transformed neurosurgery, enabling precise, minimally invasive approaches. Modern tools—operating microscopes with video, image-guided navigation (neuronavigation), endoscopes, and intraoperative monitoring—help surgeons reach deep-seated targets through smaller corridors, minimize injury to normal brain, and improve safety.

• Minimally Invasive Surgery: Using preoperative MRI with fiducial markers and real-time navigation, surgeons plan the smallest, safest craniotomy and trajectory. Intraoperative ultrasound confirms location; neurophysiologic monitoring alerts to proximity of critical neural pathways; ultrasonic aspirators and lasers debulk tumor while sparing healthy tissue.
• Skull Base Techniques: For complex skull-base tumors, meticulous approaches, intraoperative monitoring, and reconstruction techniques are used to maximize tumor control and preserve neurologic function.
• Endoscopic Approaches: Endoscopic transnasal surgery for pituitary tumors and intraventricular endoscopic resections allow panoramic visualization through narrow corridors, reducing brain retraction and morbidity.
• Endovascular/Hybrid Procedures: In selected cases, intraoperative angiography guides vascular tumor or aneurysm management; temporary flow control and immediate assessment of blood flow can reduce complications.

Chemotherapy and Systemic Therapy

Treatment strategies depend on tumor type, location, extent, and patient status. In addition to surgery and radiation, options include chemotherapy and immunotherapy. Because the blood–brain barrier (BBB) limits drug penetration, agents that cross the BBB are preferred; alternatively, intrathecal or intraventricular delivery may be used in specific conditions. Some tumors—such as primary CNS lymphoma and germ cell tumors—are particularly chemosensitive and can sometimes be cured with systemic therapy.

For metastatic brain tumors, initial management often includes measures to reduce intracranial pressure and radiation therapy to control intracranial disease, followed by systemic therapy directed at the primary cancer. Side effects (nausea, vomiting, mucositis, diarrhea, abdominal pain, alopecia, infections) are typically manageable with preventive and supportive care. Targeted therapies and personalized medicine based on tumor genetics are increasingly used across oncology and are being integrated into neuro-oncology where appropriate.

Radiation Therapy for Brain Tumors

Radiation indications, techniques, and doses vary by histology. Because many malignant brain tumors infiltrate locally and extracranial spread is rare, local control is crucial. Postoperative radiation reduces local recurrence risk even after apparent gross-total resection; it is essential when only partial resection or biopsy is feasible.

• Postoperative External-Beam Radiation: Typical courses last ≥6 weeks. 3-Dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) shape dose to the target while sparing normal brain.
• 3D-CRT Workflow: Creation of a custom immobilization device → planning CT imaging → target and organ-at-risk contouring → optimization of beam angles and dose distribution to maximize tumor coverage and minimize normal tissue dose.
• Palliative Whole-Brain/Partial-Brain Radiation: Often used for metastatic disease to relieve symptoms and improve quality of life, typically over 1–2 weeks. Selected patients may benefit from more aggressive approaches (surgical resection, stereotactic radiosurgery, IMRT).
• Stereotactic Radiosurgery (SRS; e.g., Gamma Knife): SRS delivers a high dose of precisely focused radiation in a single session (or in a few sessions) to a well-defined target, achieving surgical-like control without an incision.
• Common indications (benign): vestibular schwannoma, pituitary adenoma, meningioma, and other well-circumscribed lesions. Reported long-term tumor control rates exceed 90–95% for many benign tumors, with high rates of cranial nerve function preservation when appropriately selected.
• Metastatic brain tumors: SRS is one of the most effective treatments, offering high local control with minimal interruption to systemic therapy. It can be used alone or with whole-brain radiation depending on disease burden and patient factors.
• Malignant primary brain tumors: SRS is typically adjunctive, used for residual or recurrent lesions after surgery and fractionated radiation.