Laser Speckle Imaging Of Microvascular And Its Application In Vascular-targctcd Photodynamic Therapy

Objective: This paper intended to measure the microvascular diameter andvelocity by the laser speckle imaging (LSI), and to establish a noninvasive, real-time,in-vivo method to monitor the biological response of microvascular during and aftervascular-targeted photodynamic therapy (V-PDT). The research results may provideexperimental basis and technical method for studing the microvascular damage effectand judging the treatment effect of V-PDT.Methods:(1) The rat saphenous artery and the rabbit ear microvasculars weremeasured by the laser speckle microscopy imaging (microLSI), optical coherencetomography (OCT) and pathological sections for diameter comparision. In windowchamber mouse (WCM), the micro artery and vein were detected by the microLSIfor velocity comparision. The velocities among microvasculars with differentdiameters were also analyzed. The velocity of the PWS lesion was compared to thenormal skin by the wide field LSI.(2) The WCMs were divided into the V-PDTgroup and the control group (only photosensitizer injection and pure laser irradiation).In order to study the damage effect of V-PDT, the diameters and velocities of thebranching microvasculars were monitored during V-PDT by the microLSI. Another49WCM microvasculars were measured by the microLSI to acquire the bloodperfusion rates. The V-PDT doses needed for closing the microvasculars withdifferent blood perfusion rates were analyzed.(3)17port wine stains (PWS) patientswith26lesions were scanned by the wide field LSI during V-PDT, the treatmenteffects of the PWS lesions were judged by a clinician3-6months after V-PDT, andthe relationship between velocity changes during V-PDT and treatment effects wereanalyzed.(4)17PWS patients with40lesions were detected by the wide field LSI before and at follow-up after V-PDT, and the relationship between velocity changesat follow-up and treatment effects were analyzed.Results:(1) There were no significant differences among the microvasculardiameters measured by the microLSI, OCT and pathology sections. The velocity ofthe micro artery was greater than the vein, and the velocity decreased with thediminution of the diameter. The velocity of PWS lesion was greater than the normalskin.(2) Compared to the control group, the diameters and velocities of the WCMmicrovasculars decreased significantly during V-PDT, some microvasculars werecompletely closed. There is a positive correlation between blood perfusion ratesand V-PDT doses needed for microvasculars closure (r=0.89, P<0.01). The smallerthe blood perfusion rate was, the less V-PDT dose was required to completely closethe vessel.(3) The PWS lesions detected immediately after V-PDT showeddecreased velocities compared to the preoperative values (1161±381vs1329±475PU, P<0.01). There is a positive correlation between velocity changes during V-PDTand treatment effects (r=0.77, P<0.01).(4) The PWS lesions detected at follow-upafter V-PDT showed decreased velocities compared to the preoperative values(1282±460vs1421±463PU, P<0.01). The velocity changes of PWS at follow-upcoincide positively with the treatment effects (r=0.73, P<0.01).Conclusions:(1) The WCM vessels were clearly imaged by the microLSI. ThemicroLSI can distinguish the velocity differences between different types, differentdiameters of microvasculars. The diameters of the microvasculars detected bymicroLSI were reliable. The wide field LSI can distinguish the velocity differencesbetween PWS and the normal skin.(2) The microLSI can be used to monitor thediameter and velocity changes of microvasculars in real time and in-vivo duringV-PDT. The blood perfusion rate can be used to determine the sensitivity ofmicrovascular during V-PDT. It was easier to close the microvascular by V-PDTwhen the blood perfusion rate was smaller.(3) The wide field LSI can noninvasivelyimage the PWS lesions in vivo and in real time and obtain PWS velocity in space andin time domain. The changes of the PWS velocity during V-PDT can reflect theeffect of V-PDT.(4) At follow-up, the decreasing rate of PWS velocity can be used as an indicator for efficacy evaluation.