The document discusses the use of Computed Tomography Perfusion (CTP) for evaluating tissue vascularity in various medical conditions, particularly acute cerebral stroke and oncological applications. It highlights the importance of perfusion studies in differentiating infarcted tissue from salvageable brain areas and outlines the specific perfusion parameters including cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time to peak (TTP). Additionally, it addresses the limitations of CTP, such as radiation exposure, and provides case studies illustrating the diagnostic process.

1. Dr. Mohamed Kamel
Lecturer of radiodiagnosis
Faculty of medicine-Menoufia university

2. Where is your provisional diagnosis?

3. Perfusion is the ‘’passage of blood, a blood substitute,
or other fluid through a vessel into an organ or tissue”.
CTP is an imaging technique allows functional
evaluation of tissue vascularity.

4. The temporal changes of tissue density
depends on the iodine concentration and
are a reflection of the nature of tissue
vascularity.
So, Perfusion studies are obtained by
monitoring the passage of iodinated
contrast through the cerebral vasculature.

5. • Oncological applications ;brain ,Pancreatic & Rectal tumors:
• Tumor characterization; grading.
• Assisting the therapeutic response, consequently the prognosis.
• Differentiating between recurrent tumor and radiation necrosis.
• Non- oncological applications:
• Acute cerebral Stroke
• To allow qualitative and quantitative evaluation of cerebral perfusion.
• To distinguish infarcted tissue from penumbra.
• Ischaemic Cardiac disease.
• Pancreatitis and pancreatic necrosis.

9. • Stroke: inadequate blood flow of brain cells causing sudden death in a
localized area.
• Caused by blockage of blood flow ( ischemic )or rupture of an artery
(hemorrhagic).
• Neuroimaging plays a vital role in the workup of acute stroke.
• The main goal of CTP is to allow qualitative and quantitative evaluation of
cerebral perfusion and to differentiate the infarct core from the ischemic
penumbra.

10. • Infarcted core; irreversible tissue
ischaemia ( non-salvageable).
• Penumbra; tissue at risk of infarction due
to hypoperfusion (may be salvaged with
early reperfusion)
• In fact re-vascularization of infarcted
core cause hemorrhage .

13. Non
contrast
CT
Ischaemic
< 3 hours IV tPA.
< 6 hours IA
therapies.
< 9 hours
hypertensive Tx,
oxygen
CTA +/- CTP.
MRI (DWI)
+/- MRA – MRP.
Not ischaemic
• Precontrast CT: Hge/ infarction / swelling.
• CTP: penumbra/core infarct.
• CTA: occlusion/ stenosis /variants.

14. • Repeated acquisitions are obtained at first pass of contrast at ROI ( about 1-2
min), Then, delayed phases ( 2-10 min)

15. • Thick perfusion slap :-
• 16 MDCT: 2.5 cm.
• 64 MDCT: 4 cm.
• 320 MDCT: full brain coverage.
• Contrast :-
• Vol. 40 ml.
• Conc. 370 mg/ml .
• Rate 4 ml/s.
• Dynamic scan: every 2 s.

16. • Scan locations: at the level of basal ganglia:- This
includes vascular areas of the brain that frequently
hypo-perfused at acute stroke cases.
• Choose ROI for :-
• Arterial input: ACA.
• Venous output: SSS.
• Time-attenuation curves for arterial ROI, venous ROI
and each pixel are obtained. This is based on the
principle that transient hyperattenuation is directly
proportional to amount of contrast .

17. • Perfusion parameters are mathematically calculated.
• Color-coded perfusion maps are obtained.
CBV
Cerebral blood volume
CBF
Cerebral blood flow
MTT
Mean transit time
TTP
Time to peak

19. • (CBV): the blood volume passing through the region of interest measured
(ml/100 g).
• (CBF): the blood flow through the tissue of interest per unit of time
measured in (ml/100 g/min).
• (MTT) : the mean time it takes for blood to circulate through capillaries of a
determined region, passing from arterioles to venule measured in seconds.
• (TTP): The time it takes to reach the maximum attenuation value within
artery measures in seconds.

20. • (CBV):
• (CBF):
• (MTT) :
• (TTP):

21. Brain tissue CBF CBV MTT
Grey matter 60 ml/ 100g/min 4 ml/ 100g 4 s
White matter 25 ml/ 100g/min 2 ml/ 100g 4.8 s
• Normal perfusion parameter

22. Core infarct Pattern:
• CT: MTT - CBF - CBV.
• MRI: DWI - T2WI - FLAIR.
• Penumbra pattern:
• CT : MTT - CBF - CBV.
• MRI: MTT on MRP

23. •Treatment 3h after event based on mismatch..
• Less mortality risk.
• Less infarct expansion.
• Better functional outcome.

24. CBV MTT

25. CBV MTT

26. CBV MTT

27. MTTCBV

29. MTT
Mismatch ( penumbra
NCECT CBF CBV MTT

30. MTT
Total match ( core infarct )

32. • The major limitation is the risk of
exposure to ionizing radiation which
limits its routine use especially in
follow-up studies.
• High radiation dose of CTP (about 3.2
Gy) induces temporary hair loss.
• Low KVp (from 120 to 80) is sufficient
to maximal dose reduction without
affection of diagnostic accuracy.

37. Check list
• Check :-
• Non contrast CT (early findings).
• All 4 CTP series for defects (Cerebral
cortex, basal ganglia and cerebellum).
•Compare CBV to MTT.
• Identify match/ mismatched defects.
•Conclude the core Vs. penumbra (ratio).

39. Case no. 1
56 y old male
patient
presented with
DCL & left
hemiparesis

40. •CBV:
•MTT:
•CBF:
•TTP:
• Match/ mismatch
• Core/Penumbra
Case no. 1

41. Answer
• CBV: Normal.
• MTT: Prolonged at right temporal lobe along the territory of RT MCA.
• CBF: Decreased at right temporal lobe along the territory of RT MCA.
• TTP: Prolonged at right temporal lobe along the territory of RT MCA.
• Match/ mismatch: mismatched CBV/MTT
• Core/Penumbra: penumbra with no core.

42. •CBV:
•MTT:
•CBF:
•TTP:
• Match/ mismatch
• Core/Penumbra
Case no. 2: Old infarction with new symptoms

43. Answer
• CBV: decreased at left frontal cortex.
• MTT: Prolonged at left cortical & deep periventricular region.
• CBF: Decreased at left cortical & deep periventricular region.
• TTP: Prolonged at left cortical & deep periventricular region.
• Match/ mismatch: mismatched CBV/MTT
• Core/Penumbra: penumbra with cortical core.

44. •CBV:
•MTT:
•CBF:
•TTP:
• Match/ mismatch
• Core/Penumbra
Case no. 3: Deep coma

45. Answer
• CBV: decreased at RT MCA territory .
• MTT: Prolonged at RT MCA territory.
• CBF: Decreased at RT MCA territory .
• TTP: Prolonged at RT MCA territory .
•Match/ mismatch: matched CBV/MTT
•Core/Penumbra: core with no penumbra .