New perfusion imaging of tissue transplants with Contrast Harmonic Ultrasound Imaging (CHI) and Magnetic Resonance Imaging (MRI) in comparison with laser-induced Indocyanine Green (ICG) fluorescence angiography.
OBJECTIVE
Evaluation of post-surgery tissue perfusion of free flaps of the lower leg with contrast enhanced harmonic imaging (CHI), laser-induced indocyanine green (ICG) fluorescence angiography and magnetic resonance imaging (MRI).


METHODS
10 patients with free flaps of the lower limb were evaluated with CHI, ICG-fluorescence angiography and perfusion weighted MRI. Perfusion weighted MRI was performed after intravenous bolus injection of 25 ml Gd-DTPA. The ICG fluorescence was detected by a near-infrared-laser device (lambda em = 780 nm). Ultrasound was carried out by an experienced examiner with a linear probe after intravenous bolus injection of 2.4 ml SonoVue. For MRI time intensity curves as well as color-coded blood volume maps of the whole free flap were qualitatively evaluated. For CHI and ICG time intensity curves in selected regions of interest were analyzed. A score from 1-5 (1 = low, 5 = excellent) was used for analysis of perfusion images by three independent readers.


RESULTS
In 3 cases (radialis, parascapular and lateral thigh flap) CHI, MRI and ICG perfusion imaging showed an excellent (score 4-5) contrast enhancement of the cutaneous and subcutaneous part of the free flaps. In 2 cases of osteocutaneous flaps perfusion in central and distal parts of the free flaps was reduced (score 2). Correlation between CHI, MRI and ICG was 0.69-0.83 for the distal parts of the free flaps and 0.74-0.87 for the center of the flaps (Spearman test). Perfusion in the center of the free flaps was significantly different for MRI and ICG and also for MRI and CHI (p<0.05, Wilcoxon test).


CONCLUSIONS
These first results introduce CHI and MRI perfusion imaging as a promising post-surgery monitoring in patients with free flaps.
Jung
E M
EM
Institute of Radiology, University Medical Center Regensburg, Regensburg, Germany. emjung@gmx.de
Prantl
L
L
Schreyer
A G
AG
Schreyer
C I
CI
Rennert
J
J
Walter
M
M
Jung
W
W
Hoffstetter
P
P
Herold
T
T
Zorger
N
N
Feuerbach
S
S
Fellner
C
C
D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000494:pharmacology*; D003952:Diagnostic Imaging; D005260:Female; D005451:Fluorescein Angiography / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007208:Indocyanine Green; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D011446:Prospective Studies; D012867:Skin / Q000098:blood supply*; D013524:Surgical Flaps / Q000098:blood supply*; D019737:Transplants
D003287:Contrast Media; D007208:Indocyanine Green