Table 2.

Controversies regarding hyperperfusion after recanalization.

References	Modality	Year	Number of subjects	Recanalization method	Definition of hyperperfusion	The time interval between recanalization and cerebral hemodynamic assessment	Impact of hyperperfusion
Perren et al. (40)	TCCS	2017	31	Mechanical thrombectomy using Solitaire stent retriever	Focal PSV increase >35% compared to the contralateral homonym artery (MCA), >40% compared to the different depths of the same vessel (BA)	Within 7 days	Not harmful
Bivard et al. (41)	ASL	2012	100	Thrombolysis in 47 subjects	Not mentioned	Not mentioned. The time interval between the onset of stroke and ASL imaging was 24 h	Beneficial
Abumiya et al. (45)	SPECT	2013	35	Thrombolysis by a total dose of 0.6 mg/kg t-PA	A CBF increase ≥25% compared with the contralateral	1 h	Beneficial
Kneihsl et al. (39)	TCD	2017	123	Mechanical thrombectomy using stent retrievers or clot aspiration systems	Not defined. Mean MBF velocity index (= recanalized MCA MBF velocity/contralateral MCA MBF velocity) was 30% higher in ICH compared with non-ICH patients	6.6 ± 2.3 h (mean ± SD)	Harmful
Yu et al. (42)	ASL	2013	221	IV t-PA, IA t-PA, clot retrieval, and stenting in 102, 11, 41, and 8 subjects, respectively	Patchy areas with visually perceivable increased CBF on ASL maps compared with the homologous contralateral hemisphere	Not mentioned. The median time interval between the onset of stroke and initial ASL imaging was 7.05 h (IQR 3.35–18.23)	Harmful

TCCS indicates transcranial color-coded duplex sonography; PSV, peak systolic velocity; MCA, middle cerebral artery; BA, basilar artery; ASL, arterial spin labeling; SPECT, single-photon emission computed tomography; t-PA, tissue plasminogen activator; CBF, cerebral blood flow; TCD, transcranial Doppler sonography; MBF, mean blood flow; SD, standard deviation; ICH, intracerebral hemorrhage; IV, intravenous; IA, intraarterial; IQR, interquartile range.