radiology imaging mri brain radiology meet feb24.pptx

ppt on radiology

1. Radiology meet: MRI BRAIN & FACE : Rhino-orbital cerebral mucormycosis Presenter: Dr Ashish Sharma Moderator: Prof Banani poddar Prof Zafar Nayaz

2. Introduction MRI is the most sensitive imaging method H yperintense and hypointense, with the gray matter being the reference point

3. Routine MRI sequences T1 weighted image T2 weighted image FLAIR DWI/ADC SWI Post contrast images To see anatomy- T1 weighted image To see pathology – T2 weighted image

4. How to recognise a sequence Fat –Subcutaneous fat Fluid – CSF Gray –white matter differentiation Contrast- look at nasal mucosa

5. T1 Weighted Image Fat- bright Fluid-dark Gray matter is gray White matter is white As in anatomy Most pathology in T1 hypointense & usually associated edema and fluid –low Signal T1 bright pathology has limited differentials: subacute bleed, fat, melanin, slow flowing blood, calcification/mineralisation

6. T2 weighted image Fat – bright Fluid/csf- bright Gray matter is bright White matter is dark (reverse anatomic) Good for detecting areas of pathology Identify patent vascular flow voids(dark) Occlusion demonstrates increased signal Most pathology –bright due to associated edema and fluid is bright in T2 Low signal in T2 has limited differential, are dense cells ( lymphoma), blood products ( acute,early subacute, and chronic), flow voids , calcification and mineralisation

7. FLAIR Similar to T2WI with signals from free water suppressed Most pathology exhibits bright signal on FLAIR Particularly helpful in demylinating disease e.g MS, Small lesions, subcortical lesions, brainstem pathology , Prone to artifacts

8. Diffusion weighted images/ADC Appearance similar to FLAIR (CSF dark and cortex is bright) Bright signal –T2 shine through/Restricted diffusion ADC (Apparent diffusion cofficient)- It outs T2 Looks like inverted DWI (CSF bright, and parenchyma dark) In diffusion restriction-its dark on ADC (sub Acute infarct) In T2 shine through- both are bright

9. SWI (Susceptibility weighted image) Identifies small foci of calcification and microbleed

10. Post contrast images Typically uses T1 WI Gadolinium is the contrast agent T1- low signal csf and high signal fat Normal enhancement of nasal turbinates Contrast with sulcal vessels and venous sinuses are unreliable Always compare with precontrast to make sure that increased signal is due to actual enhancement Always look for leptomeningeal enhancement- too much enhancement along surface of cerebral sulci , cerebellar folia and surrounding brainstem FLAIR post contrast has more sensitIvity

11. Identifiable patterns T1 –fluid dark, fat bright, G-W anatomic T2- fluid bright G-W reverse anatomic FLAIR- fluid dark, G-W reverse anatomic DWI- looks like FLAIR, no visualised calvarium /scalp ADC- Fluid bright , brain dark, very low resolution SWI- prominent dark vessels T1 Post contrast- T1WI with increased signal in vessels and nasal turbinates

12. Sequences for specific pathology T1 -anatomic localisation , T1 signal subacute blood and fat T2 – flow voids, T2 signal aging blood, dense cells and vascularity FLAIR – identify and localise pathology DWI/ADC-evaluated for restricted diffusion SWI-most sensitive sequence for hemorrhage , calcification Post contrast- evaluate for enhancement (intra-axial and extra axial) Heavily T2WI- evaluate cranial nerve pathology

13. Signal On T1 W images On T2 W images Dark Air, cortical bone, stones, some calcifications , flow voids in vessels, ligaments, tendons , scar Air, cortical bone, stones, some calcificatoins , flow voids in vessels, ligaments, tendons , scar Intermediate Water, muscles, gonads, spleen , liver Muscle, liver, pancreas, hyaline cartilage Bright Fat, fatty marrow, proteinaceous material, meth Hb , melanin, contrast enhanced tissue Water , fat, red marrow , oxyHb and extracellular meth Hb

14. S ystematic approach  Midline and going laterally. S tart from the ventricle, surrounding subcortical structures, brain lobes, cerebral cortex, to meninges and skull. 

15. MAGNETIC RESONANCE IMAGING FACE T1- weighted (T1W) images  - Tissues with shorter T1-relaxation times like fat appear brighter than those with longer T1-relaxation like water/vitreous/CSF T2- weighted (T2W)mages  - Tissues with longer T2-relaxation like water/vitreous/CSF, appear brighter than tissues with shorter T2-relaxation like blood products

16. T1 T2

17. Fluid attenuation inversion recovery (FLAIR) Signal from fluid can be suppressed using the FLAIR sequence. FLAIR is especially useful in demyelinating conditions where the white matter hyperintensities on T2W images are better appreciated when the bright signal from the adjacent CSF in the ventricles is nulled.

18. Postcontrast images Gadolinium CAUSES shortening of T1-relaxation times, which results in brighter areas on T1W images. Therefore postcontrast images are always obtained with T1 weighting The optic nerve does not normally enhance

19. Fat-suppressed images   Bright signal from intraorbital fat can mask the signal and enhancement of pathology. This problem can be overcome by suppressing the signal of fat by special fat suppression sequences.  

20. Heavily T2W images This sequence helps in better visualization and tracing the course of the cisternal portions of the cranial nerves (useful in cases of suspected 3  rd  nerve palsy).

21. 44yr male mr. vishnu , Residence:Lucknow , Occupation:Policeman Comorbidities: Post liver transplant on 3/1/24 Type 2 DM since 10 years  CKD since 10 years Hypothyroidism since 8 months Activity status prior to illness: good   PRESENTING COMPLAINTS: Abdominal distension – 15/11/23 Reduced urine output – 15/11/23 Dry cough since – 01/12/23 Pain abdomen – 20/12/23 Seizures and altered sensorium -20/01/24 Nasal discharge & Left side facial swelling 21/01/24 Post liver transplant on 03/01/24

22. THANK YOU