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
• Hyperintense 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
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. • Systematic approach
• Midline and going
laterally.
• Start 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
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.
19. 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
20. 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.
21. 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).
22. • 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
