Case presentation

Case presentationSharon H. de Kock

August 2012

CLINICAL HISTORY

33yr femaleReferred with hx of numbness of 1st 2

digits of Rt hand, also focal convulsions affecting the Rt corner of her mouth.

According to pt she was healthy before Feb ‘12.

No other relevant hx/ illnesses.

CLINICAL EXAMINATION

GCS 15/15Orientated to place, person, time.Higher functions in tact.

SPECIAL INVESTIGATIONS

CXRMRI of Brain & SpineScintigram

MRI FINDINGS

Multiple high signal nodules and mass on T1.Involving the cerebrum and cerebellum.Intra-axial.Largest in Lt parietal region approx 3.5 x 4 cm

axially & 4.5 cm cranio-caudally.Largest in post fossa on Lt approx 1.3 cm CC &

2 x 2.2 cm axially.Spectroscopy of Lt large parietal mass: lactate

peak suggestive of necrosis/ infection, no increased Ch/NAA ratios.

MRI FINDINGS cont.

Vasogenic oedema surrounding mass cause mass effect on lat ventricle and midline.

Basal cisterns patent.Prominent post C enhancement.Central necrosis.GE: blooming artefact suggestive of

hemosiderin & chronic blood.

MRI FINDINGS cont. (spine)

No abnormal signal changes in the spinal cord.

Few high signal intensity lesions in the vertebral bodies- T4, T11 & L4- ?fat.

DIFF DX

Haemorrhagic mets.Meningeal melanotosisNeuro-cutaneous melanosis.

SKELETAL SCINTIGRAM

No convincing evidence of skeletal mets.

ANATOMICAL PATHOLOGY

METASTATIC MALIGNANT MELANOMA

T1 PHYSICS

T1 relaxation is the process of longitudinal magnetization recovery after applying a RFP/ excitation to invert the vector.

Occurs as energy from the spinning nuclei is dissipated into surrounding areas.

Substances with intrinsic shorter T1 relaxation times demonstrate higher signal intensity on T1WI.

HIGH SIGNAL INTENSITY ON T1WI

Various natural occurring substances are responsible- (reduce T1 relaxation time)*methemoglobin, *melanin, * lipid, *protein, *calcium, *iron, *copper and *manganese.

CLASSIFICATION

CLASSIFICATION

METHEMOGLOBIN-CONTAINING LESIONS

Physical Properties:- MRI appearance of haemorrhages & lesions containing blood depends on the age of the blood.- intracellular methemoglobin= early sub- acute phase haemorrhage, 3-7d after onset.- extracellular methemoglobin= late sub- acute phase, 8d-1mnth after onset.

METHEMOGLOBIN-CONTAINING LESIONS, Physical Properties cont.

- produce T1 shortening effects.- therefore have intrinsically high signal intensity on T1WI.- attributed to paramagnetic interactions.

METHEMOGLOBIN-CONTAINING LESIONS

Cavernous Malformations:- congenital/ acquired vascular anomalies.- occur in approx. 0.5% of general population.

Cerebral Venous Thrombosis:- unusual condition.

CAVERNOUS MALFORMATION

CEREBRAL VENOUS THROMBOSIS

MELANIN-CONTAINING LESIONS

Physical Properties:- demonstrate high signal intensity on T1WI because of the paramagnetic effects of stable free radicals and metal scavenging effects.

MELANIN-CONTAINING LESIONS

Metastatic Melanoma:- intracranial mets occur in nearly 40% of pts with malignant melanoma.- high signal intensity also can result from haemorrhage within these lesions.

Prim Diffuse Meningeal Melanomatosis:- aggressive form of prim intracranial melanoma, extremely rare.

PRIMARY DIFFUSE MENINGEAL MELANOMATOSIS

MELANIN-CONTAINING LESIONS, cont.

Neurocutaneous Melanosis:- uncommon congenital condition characterized by multiple giant or hairy nevi and melanin containing lepto- meningeal lesions without evidence of extracranial melanoma.

LIPID-CONTAINING LESIONS

Physical Properties:- short T1 relaxation time of hydrogen nuclei within lipid molecules.- produces high signal intensity on T1WI.

LIPID-CONTAINING LESIONS

Intracranial Lipomas:- rare congenital malformation.- arise from abnormal differentiation of the persistent primitive meninx.- commonly occur in pericallosal region, often associated with disgenesis or agenesis of the corpus callosum.

INTRACRANIAL LIPOMA

LIPID-CONTAINING LESIONS, cont.

Teratomas:- true neoplasms, usually contain tissue derived from all three germ cell layers.- mostly benign, malignant variants exist.- most frequently found in the cerebral hemispheres and pineal gland.

Dermoid Cysts:- rare, benign, congenital ectodermal inclusion cysts, commonly in midline.

PINEAL TERATOMA

PROTEIN-CONTAINING LESIONS

Physical Properties:- high signal intensity of certain lesions on T1WI can be attributed to their protein content and the hydration layer effect.

PROTEIN-CONTAINING LESIONS

Colloid Cyst:- uncommon benign intracranial lesions.- contain gelatinous material.- occur characteristically at the antero- superior aspect of the 3rd ventricle.

Rathke Cleft Cyst:- common benign remnants of the Rathke cleft, may be located in sellar-/ supra- sellar compartment.

COLLOID CYST

RATHKE CLEFT CYST

MINERAL-CONTAINING LESIONS

Physical Properties:- Calcium is a diamagnatic substance that may appear bright on T1WI.- Other minerals that have T1 shortening effects include manganese, copper and iron.

MINERAL-CONTAINING LESIONS

Hepatic Encephalopathy:- characteristically manifests as bilateral regions of high signal in the lentiform nucleus and substantia nigra on T1WI.- related to the accumulation of manganese.

Wilson Disease:- rare autosomal recessive condition.- resultant abn copper metabolism & acc.- basal ganglia & thalami commonly affected.

HEPATIC ENCEPHALOPATHY

WILSONS DISEASE

TAKE HOME POINT

Familiarity with substances and physical properties that contribute to T1 shortening is helpfull to formulate an appropriate Diff Dx.

OUR PT?

Could still not find the primary lesion.Referred to Oncology.

REFERENCES

Intracranial Lesions with High Signal Intensity on T1-weighted MR Images: Differential Diagnosis, RadioGraphics 2012; 32:499-516.

Grainger & Allison’s Diagnostic Radiology, 5th Edition, Volume 2.