Ramzes Chavez MD
Ramzes Chavez MD

@ChavezRamzes

11 Tweets 4 reads Feb 10, 2025
🩻🧠☠️🧡 MRI Modalities & Their Key Uses in Neurosurgery
1/ MRI is essential for neurosurgical diagnosis, planning, and postoperative assessment.
βœ… High soft-tissue contrast
βœ… Non-ionizing radiation
βœ… Multiple modalities for different pathologies
πŸš€ MRI sequences & their role in neurosurgery! πŸ‘‡
#Neurosurgery #NeuroRadiology #MRI
image: radiopaedia.org
2/ T1-Weighted MRI β†’ Anatomy & Tumor Enhancement
πŸ–₯️ Appearance:
βœ… Gray matter = Dark
βœ… White matter = Bright
βœ… CSF = Dark
πŸ“Œ Key Uses in Neurosurgery:
βœ… Anatomical detail of brain structures
βœ… Pre- & Post-contrast Imaging β†’ Tumor enhancement after gadolinium injection
βœ… Identifies fat-containing lesions (e.g., dermoid cysts, lipomas)
🚨 T1 + Gadolinium = Best for BBB breakdown (tumors, infections, inflammation)!
3/ T2-Weighted MRI β†’ Edema & Pathology Detection
πŸ–₯️ Appearance:
βœ… CSF = Bright
βœ… Edema = Bright
βœ… Gray matter = Bright, White matter = Dark
πŸ“Œ Key Uses in Neurosurgery:
βœ… Detects vasogenic & cytotoxic edema (brain tumors, strokes, infections)
βœ… White matter demyelination (MS, PML, leukodystrophies)
βœ… Cystic & necrotic tumor components
🚨 Best for detecting pathological changes!
image: radiopaedia.org
4/ FLAIR (Fluid-Attenuated Inversion Recovery) β†’ Subtle Edema & Gliosis
πŸ–₯️ T2-based sequence but suppresses CSF signal!
βœ… CSF = Dark
βœ… Edema, demyelination, gliosis = Bright
πŸ“Œ Key Uses in Neurosurgery:
βœ… Detects peritumoral edema & gliosis
βœ… Subtle cortical & periventricular lesions (MS, encephalitis, gliomas)
βœ… Distinguishes CSF from pathological fluid (tumors, ischemia, infections)
🚨 Best for identifying lesions near CSF spaces!
5/ DWI (Diffusion-Weighted Imaging) β†’ Stroke & Abscess Detection
πŸ–₯️ Measures water diffusion in tissues
βœ… Restricted diffusion = Bright signal (ischemic core, pus, dense tumors)
βœ… Normal diffusion = Dark signal
πŸ“Œ Key Uses in Neurosurgery:
βœ… Acute Ischemic Stroke β†’ Restricted diffusion in infarct core
βœ… Brain abscesses β†’ Pus has restricted diffusion
βœ… Epidermoid cysts vs. Arachnoid cysts β†’ Epidermoids restrict on DWI
βœ… High-grade gliomas & metastases β†’ Can show restricted diffusion
🚨 DWI + ADC (Apparent Diffusion Coefficient) needed for stroke timing!
6/ SWI (Susceptibility-Weighted Imaging) β†’ Microbleeds & Hemorrhage
πŸ–₯️ Detects paramagnetic substances (blood, iron, calcium)
βœ… Microbleeds, Hemosiderin = Dark
βœ… Iron deposition in neurodegeneration = Dark
πŸ“Œ Key Uses in Neurosurgery:
βœ… Microhemorrhages (Trauma, CAA, Hypertensive encephalopathy)
βœ… AVMs, Cavernous Malformations
βœ… Hemorrhagic transformation of stroke
βœ… Detection of intra-tumoral hemorrhage
🚨 Best for detecting chronic & microscopic bleeds!
image: DOI: 10.1038/srep38561
7/ MR Angiography (MRA) & MR Venography (MRV) β†’ Vessel Imaging
🩸 Non-invasive imaging of arteries (MRA) & veins (MRV)
βœ… Without contrast (TOF-MRA) or with gadolinium (CE-MRA)
πŸ“Œ Key Uses in Neurosurgery:
βœ… MRA β†’ Detects aneurysms, stenosis, arteriovenous malformations (AVMs)
βœ… MRV β†’ Diagnoses cerebral venous sinus thrombosis (CVST)
βœ… Preoperative vascular mapping for aneurysm & AVM surgery
🚨 MRA/MRV critical for neurosurgical planning!
image: radiopaedia.org
8/ MR Perfusion (PWI) β†’ Tumor & Stroke Perfusion Analysis
πŸ–₯️ Measures blood flow dynamics in brain tissue
βœ… CBF (Cerebral Blood Flow), CBV (Cerebral Blood Volume), MTT (Mean Transit Time)
πŸ“Œ Key Uses in Neurosurgery:
βœ… Distinguishes high-grade vs. low-grade gliomas (CBV ↑ in aggressive tumors)
βœ… Assessing penumbra in stroke (Mismatch between DWI & PWI)
βœ… Pre- & post-surgical monitoring of tumor perfusion
🚨 Best for evaluating glioblastomas & ischemic strokes!
Image: doi.org
9/ MR Spectroscopy (MRS) β†’ Metabolic Tumor Analysis
πŸ–₯️ Analyzes chemical composition of brain tissue
βœ… Differentiate tumors vs. abscesses vs. radiation necrosis
πŸ“Œ Key Uses in Neurosurgery:
βœ… Glioblastoma vs. Metastases vs. Lymphoma (Choline/NAA ratio differences)
βœ… Radiation necrosis vs. tumor recurrence
βœ… Lactate peak β†’ Anaerobic metabolism (Abscesses, high-grade tumors)
Image: radiopaedia.org
10/ Functional MRI (fMRI) β†’ Preoperative Brain Mapping
🧠 Detects brain activity by measuring blood oxygenation (BOLD signal)
βœ… Identifies critical functional areas (Motor, Speech, Vision, Memory)
πŸ“Œ Key Uses in Neurosurgery:
βœ… Pre-surgical mapping of eloquent cortex (Motor, Speech areas)
βœ… Glioma & epilepsy surgery planning
βœ… Localizing brain regions for neurostimulation therapy
🚨 Crucial for minimizing post-surgical deficits!
Image: biorender.com
11/ Diffusion Tensor Imaging (DTI) β†’ White Matter Tract Mapping
🧠 Visualizes white matter tracts using diffusion-based MRI
βœ… Fractional Anisotropy (FA) β†’ Measures white matter integrity
πŸ“Œ Key Uses in Neurosurgery:
βœ… Brain tumor resection planning (Avoiding motor/sensory tracts)
βœ… Traumatic brain injury (TBI) assessment
βœ… Spinal cord injury evaluation
🚨 Essential for preserving functional pathways in surgery!
Image: DOI: 10.4236/jbise.2016.913052

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