ExtendedProperties in Get-AzSecurityAlerted into Variable in PowerShell

When i run the command get-azsecurityalert, i get the following result:

Id                 : /subscriptions/4b06/resourceGroups/GUD01/prov
                     iders/Microsoft.Security/locations/centralus/alerts/256470605332_2de8ba64-8ec8-47-8ce0-00
                     4f77588f3f
Name               : 4777-8ce0-00488f3f
ActionTaken        : Undefined
AlertDisplayName   : Azure Security Center test alert (not a threat)
AlertName          : SCUBA_RULE_ASC_EICAR
AssociatedResource : /subscriptions/6e6ab4b06/resourceGroups/CCLOUD01/prov
                     iders/Microsoft.Compute/virtualMachines/azrapp007
CanBeInvestigated  : True
CompromisedEntity  : RAPP007
ConfidenceReasons  : {}
ConfidenceScore    :
Description        : This is a test alert generated by Azure Security Center. No further action is needed.
DetectedTimeUtc    : 25/09/2019 10:42:32
Entities           : {Microsoft.Azure.Commands.Security.Models.Alerts.PSSecurityAlertEntity,
                     Microsoft.Azure.Commands.Security.Models.Alerts.PSSecurityAlertEntity,
                     Microsoft.Azure.Commands.Security.Models.Alerts.PSSecurityAlertEntity,
                     Microsoft.Azure.Commands.Security.Models.Alerts.PSSecurityAlertEntity...}
ExtendedProperties : {[compromised Host, AZRAPP007], [user Name, Kloud\KellyGarcia], [account
                     Session Id, 0x13ce9cc], [suspicious Process,
                     c:\users\Kelly.Garcia\desktop\asc_alerttest_662jfi039n.exe]...}
InstanceId         : 2de8ba64-8ec8-4777-8ce0-004f77588f3f
RemediationSteps   : No further action is needed.
ReportedSeverity   : High
ReportedTimeUtc    : 25/09/2019 10:43:11
State              : Active
SubscriptionId     : d7644790-4c1a-4a7c-8817-df76e6ab4b06
SystemSource       : Azure
VendorName         : Microsoft
WorkspaceArmId     : /subscriptions/b68d365f314ad67/resourcegroups/rg-dev-loganalytics001/provider
                     s/microsoft.operationalinsights/workspaces/godevopsla001

i need the process name in a varialble which is under extended properties:

ExtendedProperties : {[compromised Host, RAPP007], [user Name, Kloud\KellyGarcia], [account
                     Session Id, 0x13ce9cc], [suspicious Process,
                     c:\users\Kelly.Garcia\desktop\asc_alerttest_662jfi039n.exe]...}

the gm for extended properties return me the following result:

   TypeName: Selected.Microsoft.Azure.Commands.Security.Models.Alerts.PSSecurityAlert

Name               MemberType   Definition
----               ----------   ----------
Equals             Method       bool Equals(System.Object obj)
GetHashCode        Method       int GetHashCode()
GetType            Method       type GetType()
ToString           Method       string ToString()
ExtendedProperties NoteProperty Dictionary[string,Object] ExtendedProperties=System.Collections.Generic.Dictionary`2...

how do i do this?