Table 4. Regional perfusion values of significant clusters.

Region	Placebo	Heroin	Effect size
	(Mean/SD/CI 95%)	(Mean/SD/CI 95%)	(Cohen's d)
Cluster 1: left Insula	97.07/10.93/91–103	82.10/10.68/73–88	1.38
Cluster 2: right Insula	79.17/11.03/73–85	69.44/12.38/63–76	0.82
Cluster 3: ACC/MPFC	108.71/16.72/99–118	92.16/19.0/82–103	0.93

ACC: Anterior cingulate cortex; CI: Confidence interval; MPFC: Medial prefrontal cortex.