Perfusion deficit

In our view, the MRI patterns for identifying the ideal candidate for thrombolysis are straightforward. This particularly applies to treatment beyond the 3-h window. A small infarct core identified by DWI and a large perfusion deficit on PI indicate the potential for a major benefit from thrombolysis. This simple, practical mismatch model has, however, been challenged by partial normalisation of... 

Thijs VN, Adami A, Neumann-Haefelin T, Moseley ME, Marks MP, Albers GW (2001) Relationship between severity of MR perfusion deficit and DWI lesion evolution. Neurology 57 1205-1211... 

Fig. 4.12. Mismatch concept of diffusion lesion (smaller) and perfusion deficit (larger) in human territorial brain infarction. Acute MCA territory ischemia/oligemia with a smaller, centrally located diffusion disturbance showing the relationship between infarct core, ischemic penumbra and changes in DWI and PI. DWI, diffusion-weighted imaging PI, perfusion imaging ADC, apparent diffusion coefficient ATP, high energy phosphates MCA, middle cerebral artery...

Fig. 7.9. Lacunar brain stem stroke. Typical example of a lacunar brain stem stroke that would be missed if only transverse DWI images were obtained ( DWI negative stroke ). In this case, a faint DWI lesion was seen on coronal sections at the acute time point, but both transverse and sagittal planes did not show an unequivocal lesion. PI, on the other hand, showed a clear-cut perfusion deficit in the brain stem. Follow-up images confirmed a small infarct in the brain stem. (Images were acquired in collaboration with P. Sterzer, Neurology, Frankfurt, and R. du Mesnil de Rochemont, H. Lanfermann, Neuroradiology, Frankfurt)...

Fig. 15.6. Computerized registration and overlay of DWI lesions on PI images, to determine the exact location of the diffusion lesion with respect to the perfusion deficit. The alignment of the time-to-peak (TTP) and DWI images demonstrates that the lesions are indeed located in the borderzone area where the extent of the perfusion deficit is most pronounced...

MRI perfusion studies have been used primarily to study perfusion deficits in stroke lesions. The mismatch between DWI and perfusion deficit may represent tissue at risk for damage (Neumann-Haefelin et al., 1999) which may be salvaged using thrombolytic therapy. However this interpretation of mismatch between DWI and perfusion MRI is controversial... 

Fifteen minutes after reperfusion, 600 pCi of201T1 is administered intravenously, and after another 15 min 201T1 distribution images (at the 80 keV photopeak with a 20% window) are obtained in the left lateral position to confirm myocardial perfusion deficit. 

AD is associated with a marked cerebral blood flow (CBF) perfusion deficit in parietotemporal cortex in addition to the global decrease in cerebral perfusion. It is of interest that the nicotinic antagonist mecamylamine reliably reproduces this abnormal CBF pattern in normal volunteers, (Gitelman and Prohovnik, 1992). Nicotine reli-... 

Fig. 1.2 Putative cascade of damaging events in focal cerebral ischemia. Very early after the onset of the focal perfusion deficit, excitotoxic mechanisms can damage neurones and glia lethaUy. In addition, excitotoxicity triggers a number of events that can further contribute to the demise of the tissue. Such events include peri-infarct depolarizations and the more-delayed mechanisms of inflammation and programmed cell death. The x-axis reflects the evolution of the cascade over time, while the y-axis aims to illustrate the impact of each element of the cascade on final outcome (courtesy of Dimagl et al. 1999)...

Fig. 5.10 CT images in a patient with left hemiparesis. Admission CTP images show cerebral blood flow (CBF, upper left), cerebral blood volume (CBV, upper middle), and mean transit time (MTT, upper right). The presence of a matched CBF/CBV perfusion deficit suggests irreversibly ischemic infarct core , likely to correlate with DWI findings, and not a target for reperfusion therapies The admission non-contrast CT...

---