Clinical validation of 2D perfusion angiography using Syngo iFlow software during peripheral arterial interventions

Endovascular surgery is an important treatment modality in peripheral arterial disease. Digital subtraction angiography is the standard post revascularisation diagnostic tool to locate lesions and to evaluate the effect of an intervention. However, interpretation of digital subtraction angiography images is subjective and it is difficult to determine whether revascularisation has been sufficient for clinical improvement. A new technique is 2D perfusion angiography, which creates a 2D colour map and time density curve from the digital subtraction angiography scan for an objective evaluation of the results. However, its clinical relevance is unknown. The aim is to evaluate the association between 2D perfusion angiography parameters and clinical outcome after peripheral arterial interventions.

In this retrospective study, post revascularisation angiographic data and clinical data were reviewed of patients who underwent treatment of femoral-popliteal or femoral-tibial arteries. The outcome was assessed at three time points using three classification systems for peripheral arterial disease: Fontaine classification, American Medical Association whole person impairment classification (AMA) and average wound, ischemia, foot infection score. Post revascularisation angiographic data consisted of time density curves of the foot and lower leg which were extracted from the Syngo iFlow system (Siemens Healthineers). For each time density curve, five descriptive parameters were calculated: time of arrival, time to peak, mean transit time, wash-in rate and area under the curve. The association between the time density curve parameters and peripheral arterial disease classification systems was assessed using a regression analysis.

Between July 2016 and December 2018, 103 patients underwent peripheral endovascular interventions in the hybrid operating room; 39 patients were suitable for analysis, of which 28 patients underwent digital subtraction angiography of the lower leg, 3 patients underwent digital subtraction angiography of the foot and 8 patients underwent digital subtraction angiography of both regions. Limited significant relations were found for time of arrival with Fontainde classification (B = 0.806, p = 0.043) and area under the curve with AMA classification (B = -0.027, p = 0.047).

In this retrospective study, time density curve parameters (time of arrival and area under the curve), measured in the lower leg, showed a limited significant association with two classification systems for peripheral arterial disease. Future prospective studies to determine the clinical relevance of this 2D perfusion angiography method should focus on standardisation of angiography protocols and comparison of pre- and post-intervention parameters.