This document provides an overview of various medical imaging modalities used to image intracranial lesions, including their uses and basic interpretations. It discusses simple radiography, CT, MRI, ultrasound, angiography, nuclear medicine scans, and PET. It also outlines the basics of reading and interpreting a CT brain scan, such as identifying anatomical structures and analyzing lesions to make diagnoses or differential diagnoses.

1. Basics for medical students By_ Dr. Rekha Khare M.D. radiology

2. Intracranial Lesion How to image?

3. Imaging modality Simple radiography -cheap preliminary screening procedure -accuracy & specificity is low

4. contd. Computerized tomography- basic choice MRI – tissue specification is better Ultrasound scan- choice in neonate & infant

5. contd. Angiography- mainly for interventional radiology

6. contd. Radionuclide scan- - basic technique is superseded by CT & MRI -Technique for mapping regional cerebral blood flow has important clinical application as in CVA, Dementia, Alzhiemers etc

7. contd. Positron emission tomography (PET) expensive & available in very advance centre ( cyclotron) PET tracer like carbon, nitrogen, oxygen - specific & showing difference in focal brain metabolism - Major use in oncology

8. contd. SPECT - Imaging of dopamine transport system in movement disorder (like Parkinsonism) by injecting specific tracer agent working at neuromuscular junction

9. When to ask brain CT scan Head injury Cerebro-vascular accident Unconscious Epilepsy Pyrexia of unknown origin Suspecting intracranial mass lesion

10. How to read CT scan brain Identification Technical details Examine the image Localize the lesion Analyse the lesion Possible diagnosis D/D if needed

11. Identification Name, age, sex, of patient Date of exam. (printed on scan)

12. Technical detail Scout film/ scanogram Plane _ axial, coronal, sagittal Number of slices Thickness of slice( 1-10mm) Window ( printed on CT scan )

13. Window means Window_ wl (window level) ww (window width) Brain window 35-40/ 70-85 Bony window 350/ 2500-3000 Sometimes subdural window (70/300) (printed on CT scan)

14. Basic idea of CT value 0-- water 20-32-- white matter 30-40-- grey matter 56-70-- blood 80-1000-- calcification to bone +100-- fat -1000-- air

15. Technical detail Plain Contrast- viable & vascular tissue take contrast ( printed on CT scan)

16. Examine the image_ a systematic approach Midline_ shift Ventricle, cistern, sulci_ enlarged, compressed, displaced Brain tissue_ iso/hypo/hyper/hetero _ mass effect _ gyri enhanced _ white matter

17. Contd. Bones/ vault( # /mass/erosion) Scalp/ soft tissue

18. Localize the lesion Commonly look for_ -air sinus_ frontal/ethmoid/sphenoid -ventricle_ LV ant./ temporal/ occipital horn _ 3 rd and aqueduct _4 th and cisterna magna

19. Contd. cistern_ cerebellopontine _ suprasellar _ quadrigeminal _ interpeduncular sulci and gyri sylvian fissure

20. Contd. Cerebral lobes_ frontal/temporal/occipital/ parietal Mid brain Brain stem cerebellum

21. Contd. Basal ganglion -caudate nucleus (head indenting ant. horn) -lentiform nucleus -external capsule (in between insula and lentiform nucleus) -internal capsule ( in between caudate and lentiform nucleus)

22. Contd. thalamus_ on either side of 3 rd ventricle pineal body choroid plexus hypothalmus basilar artery great vein of galen ( post. to pineal)

23. Contd. corpus callosum -genu ( ant. to ant. horn of LV) -splenium (post. to occ. horn of LV) septum pellucidum tentorium( dura seperating cerebellum from cerebrum)

24. Contd. venous sinus -sigmoid ( along petrous/ temporal bone) -transverse( between sigmoid and sup. sagittal sinus) -superior sagittal sinus( midline, falx meets inner skull table)

25. Contd. white matter/ corona radiata foramen magnum -spinal cord -vertebral artery

26. Analyse the lesion Intra/ extra axial Supra/ infra tentorial Single/ multiple/diffuse White/ grey matter/ both Enhancement -non enhanced_ avascular -hyper enhanced_ vascular -heterogenous enhanced_ mass

27. Possible pathology Mass Infarction Haemorrhage Hypoxic demyelinating/ degenerative

28. Possible etiology congenital/ developmental traumatic infection/inflammatory mass/ neoplasm parasitic vascular degenerative metabolic/ toxic iatrogenic/ post procedural

29. Onset of lesion acute sub acute chronic recurrent residual old healed

30. Possible diagnosis In correlation with_ age, sex clinical signs and symptoms other imaging results any lab tests

31. Differential diagnosis_ common Intra axial_ m_ mass/ metastasis a_ abscess/ angioma g_ glioma/ gliosis i_ infarction/ infection/ inflamation c_ contusion/ congenital dr_ demyelination/degenerative

32. Contd. Extra axial_ meningioma pit. Adenoma craniopharyngioma chordoma schwanoma lipoma dermoid/ epidermoid

33. Sample report This is CT scan of head done on ----- for ----- age --- Axial cuts in----mm slices from foramen magnum to vertex Plain and enhanced views with brain and bone window are included Radiological findings are----- In clinical context of ----- duration these findings suggest -------- Other D/D( if needed) could be----

34. Few pictures Material collected while working as consultant radiologist in university teaching hospital Lusaka Zambia

35. Brain trauma depressed # with brain haematoma causing mass effect

36. Brain trauma Subdural haematoma

37. Mass at top of head Predominantly extracranial mass destruction of bones

38. Intracranial mass-plain Well outlined hyperdense mass in frontal lobe ?Meningioma

39. Same case- contrast Huge hyperdense enhanced mass from falx with oedma in surrounding brain tissue ? meningioma

40. Brain mass Heterogenous enhanced cystic mass compressing 4 th ventricle causing hydrocephalus

41. Brain mass Heterogenous enhanced solid mass , compressing 4 th ventricle causing hydrocephalus

42. Brain mass Strongly enhanced mid line lesion within 4 th ventricle causing obstructive hydrocephalus ? ependymoma

43. Brain mass Hypodense nonenhanced mass in cerebellar region displacing 4 th ventricle ? Glioma

44. Brain mass Cystic mass with calcification compressing/ displacing 4 th ventricle with hydrocephalus ? ependymoma

45. Brain mass Heterogenous cystic mass with mass effect

46. Brain mass Cystic mass lesion causing dilated LV ? colloidal cyst

47. Brain mass Calcified mass at level of 3 rd ventricle

48. Brain mass Strongly enhanced mass lesion at pitutary level ? Adenoma

49. Brain mass _ metastasis Extradural deposit with bone destruction_ Primary unknown

50. Brain mass _ metastasis Deposit with bone destruction

51. Brain mass _ plain Hyperdense mass with oedma, mass effect, falx calcification?

52. Same case _ contrast ? Malignant Meningioma

53. CVA_ acute hemiplegia Intracerebral haematoma basal nuclei region with mass effect

54. CVA _ acute hemiplegia Acute infarct

55. Old case hemiplegia Hypodense lesion with no mass effect Overfilled lateral ventricle ? Few days old infarction

56. CVA_ Acute hemiplegia Serpegenious strongly enhanced lesion with mass effect ?AVM Angiography is next modality to confirm

57. Unconscious Brain oedma_ (White cerebellar sign)

58. Dementia Multiple hypodense lesion mainly peripheral ? Infarcts in old age

59. Neonatal brain Dilated ventricle compressing brain tissue, few calcification HIV+ve mother ? CMV

60. Neonatal brain Dying/ hypoxic brain

61. Brain infection _ plain Acute hydrocephalus

62. Same case _ contrast Acute hydrocephalus with meningeal enhancement

63. Brain infection _ plain Chronic SDE with mass/ pressure effect

64. Same case _ contrast Enhanced membrane _ subdural empyema

65. Infection_ plain Vague hypodensity with mass effect

66. Same case _ contrast Multiple ring enhanced lesion ? abscess

67. Fever_ plain Thin ring lesion with massive oedma & mass effect

68. Same case_ contrast Multiple ring enhanced lesion with midline shift & mass effect- ? abscesses

69. HIV+ve case_ plain Multifocal hypodense lesion with no mass effect

70. Same case- contrast Enhanced nodular lesion? opportunistic infection

71. HIV+ve case Multinodular enhanced lesion with massive oedma

72. HIV+ve case Multinodular hyperdense lesion with massive oedma

73. HIV+ve case Basal ganlion calcification

74. Epilepsy/ fits calcifiation in periventricular region ? Tuberous sclerosis

75. Epilepsy/fits Cysticercosis

76. Acute Headache Dilated ventricles with meningeal enhancement ? meningitis

77. Post procedural Shunt seen Bilateral subdural effusion Common complication Rabbit ear appearance

78. Unsteady gait Cerebellar atrophy