Contrast harmonic ultrasound and indocyanine-green fluorescence video angiography for evaluation of dermal and subdermal microcirculation in free parascapular flaps.

PURPOSE: Contrast harmonic ultrasound (CHI) with a linear transducer is a new diagnostic approach that allows dynamic and quantitative flow detection of tissue perfusion in microsurgery. The aim of the study was the evaluation of perfusion of the dermal and subdermal layers of microvascular tissue transplants with CHI in comparison to ICG-fluorescence angiography. MATERIAL AND METHOD: In a prospective clinical study Indocyanine-Green Fluorescence Video Angiography and Contrast Enhanced High Resolution Ultrasound (5-10 MHz; linear transducer; Logiq 9; GE) were used for evaluation of the microcirculation in 10 transplanted free parascapular flaps. Two regions were analysed, the centre of the flap and the region of the anastomosis. The perfusion patterns of both methods were compared. RESULTS: The perfusion indexes measured by ICG-fluorescence angiography correlated very precisely in all patients with the quantitative perfusion curves of contrast-enhanced US with CHI. Two flaps with slow filling and low dye intensity showed low contrast enhancement in CHI with modified perfusion curves with slow increase. In two cases a reduced perfusion and filling were found. There were no statistical differences between the two diagnostic methods (p>0.01). CONCLUSION: CHI improves US detections of dermal and subdermal microcirculation in comparison to ICG fluorescence angiography. CHI is a new diagnostic method for postoperative monitoring of free flaps.

Contrast harmonic ultrasound and indocyanine-green fluorescence video angiography for evaluation of dermal and subdermal microcirculation in free parascapular flaps.

PURPOSE: Contrast harmonic ultrasound (CHI) with a linear transducer is a new diagnostic approach that allows dynamic and quantitative flow detection of tissue perfusion in microsurgery. The aim of the study was the evaluation of perfusion of the dermal and subdermal layers of microvascular tissue transplants with CHI in comparison to ICG-fluorescence angiography. MATERIAL AND METHOD: In a prospective clinical study indocyanine-green fluorescence video angiography and contrast enhanced high resolution ultrasound (5-10 MHz; linear transducer; Logiq 9; GE) were used for evaluation of the microcirculation in 10 transplanted free parascapular flaps. Two regions were analysed, the centre of the flap and the region of the anastomosis. The perfusion patterns of both methods were compared. RESULTS: The perfusion indexes measured by ICG-fluorescence angiography correlated very precisely in all patients with the quantitative perfusion curves of contrast-enhanced US with CHI. Two flaps with slow filling and low dye intensity showed low contrast enhancement in CHI with modified perfusion curves with slow increase. In two cases a reduced perfusion and filling were found. There were no statistical differences between the two diagnostic methods (p>0.01). CONCLUSION: CHI improves US detections of dermal and subdermal microcirculation in comparison to ICG fluorescence angiography. CHI is a new diagnostic method for postoperative monitoring of free flaps.

Value of high resolution ultrasound and contrast enhanced US pulse inversion imaging for the evaluation of the vascular integrity of free-flap grafts.

OBJECTIVE: The aim of this study was to evaluate the clinical value of color coded Doppler sonography (CCDS) and contrast-enhanced harmonic imaging (CHI) for ultrasound (US) monitoring the integrity of free-flap vascular grafts. Patency of microvascular anastomoses and perfusion as well as microcirculation of the transplanted tissue were analysed. PATIENTS AND METHODS: Fifteen free parascapular flap grafts performed over a period of three years by a single surgeon were examined with CCDS and CHI. The patients (12 male, 3 female) ranged in age from 16 to 60 years (average age 40+/-12). The follow-up period ranged from two weeks to 2.5 years. CCDS were performed with a multifrequency linear transducer (5-10 MHz, Logiq 9, GE) with 3D flow detection. For detection and characterization, B scan of the flap tissue was compared to tissue harmonic imaging (THI) and Cross Beam with Speckle Reduction Imaging (SRI). US Pulse Inversion Harmonic Imaging (PIHI) after bolus injection of 2.5 ml Sonovue was used for contrast enhancement. RESULTS: Border and tissue structure of the flaps could be detected best in all 15/15 cases using Cross Beam Technology with SRI and THI. Correlations were found for flow parameters of the common femoral artery, popliteal artery and lower leg artery to the anastomotic vessels. 3D imaging with CCDS facilitated flow detection of elongated and small anastomotic vessels in 4/15 cases. Contrast-enhanced US with PIHI allowed dynamic flow detection of the microcirculation of the transplanted tissue over a depth of up to 3 cm with quantitative perfusion curves of the tissue microcirculation. Reduced US contrast enhancement with modified perfusion curves was seen in 2/15 cases with low anastomic flow in CCDS. CONCLUSION: Assessment of microvascular perfusion with contrast-enhanced ultrasound can provide valuable information on free flap viability. Contrast-enhanced US enables dynamic and quantitative flow detection of free flap tissue.