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INTRODUCTION connecting the anterior superior iliac spine (ASIS) to the
superolateral corner of the patella (hereafter referred to
The anterolateral thigh (ALT) flap has become an as the AP line). The distance between these two points
increasingly popular reconstructive option due to its were measured, and the AP line was divided into 10 equal
versatility of design, ability to be thinned and minimal parts (hereafter referred to as segments) for the purpose
donor site morbidity. The major limitation of this flap is of standardization between individuals and comparison.
the uncertainty in predicting perforator anatomy due to The Doppler signals were assessed at three main sites with
[1]
variability in perforator size and course. Formal analysis a radius of 3 cm. A signal at the midpoint of the AP line
of these variations has not been adequately explored. corresponded to segment 5, while the others 5 cm proximal
Many authors have described the common location of ALT and distal to midpoint corresponded to segments 4 and 6,
perforators as a tool in guiding flap harvest, but few have respectively. The most audible signals were marked each
highlighted the inconsistencies. To improve operative time by the same observer in all patients. The distance of
[1]
planning, preoperative imaging is being increasingly the Doppler signals from the AP line were plotted on the
utilized. In the past, Doppler ultrasound has been used X-axis (horizontal) and from a perpendicular drawn at the
for perforator mapping, with most studies demonstrating midpoint of the AP line, on the Y-axis.
high sensitivity but poor accuracy and high interobserver
variability. Despite improvements in ultrasound technology, Randomization into two groups
this technique has been frequently abandoned, and there Following Doppler assessment, patients were randomized
are trends toward performing no preoperative localization into two groups using computer-generated random
at all. Multi-detector row computed tomography numbers. Blocks of four were used to aid adequacy in
[2]
angiography (MDCTA) has become a powerful noninvasive randomization. In the first group (Group 1), preoperative
alternative to conventional digital subtraction angiography mapping of location, number, source vessel, and course of
in preoperative imaging. [3-5] The utility of MDCTA for all perforators of the ALT using an MDCTA was performed.
preoperative planning in comparison with Doppler and In the second group (Group 2), no preoperative MDCTA
effectiveness of the ABC system in preoperative perforator was performed.
localization has not been studied in an adequate number of
patients in the Indian population. The present randomized MDCTA
controlled study was been designed to investigate the MDCTA was performed using a 64-detector row computed
utility of preoperative imaging in the localization of tomography scanner with the following parameters: 120
perforators and design of the skin paddle. Flap harvest kVp, 80-120 mA, gantry rotation time 0.4 s, detector
time, surgeon’s stress levels, and operative outcome were configuration 16 mm × 1 mm, 23 mm table travel per
also assessed. rotation, 512 × 512 matrix, and 180-240 field of view. All
scans were performed with intravenous (IV) administration
METHODS of 100 mL of nonionic iodinated contrast medium with
a concentration of 300 mg/mL and injected at a rate of
Patients 4 mL/s through an 18-gauge IV catheter inserted into
In patients undergoing free ALT flaps, the goals were (1) an antecubital vein. A bolus tracking technique was
to compare the number, location, course, and source of employed to obtain images from the point of bifurcation
cutaneous perforators with the use of preoperative MDCTA of the abdominal aorta to the level of the knee joint. The
and a handheld Doppler device, with intraoperative volumetric data acquired was then retrospectively used to
observation as the gold standard; and (2) to compare the reconstruct images with a slice thickness of 2 mm and a
subjective stress levels of the surgeon during perforator reconstruction interval of 0.75 mm in a soft tissue kernel.
dissection and flap harvest time in patients who had Ten radio-opaque markers (1 cm diameter plastic buttons)
preoperative MDCTA versus those who did not. were placed at equal intervals along the AP line to depict
each segment that assisted in accurate localization of
The pilot study done between January and December 2011 perforators on preoperative MDCTA, which were plotted
included all patients who required a free ALT flap. Patients on the X-axis and Y-axis + or − symbols were used to
with a documented history of significant atherosclerotic depict the distances as plotted on the graph keeping the
disease with blockage at the level of the infrarenal aorta, midpoint of intersection of AP line as (0, 0). These were
lower limb infections, scars, prior surgery to the thighs, then compared to the intraoperative findings.
and preexisting renal disease, diabetes, or cardiovascular
disease were excluded. Operative technique
All patients underwent harvest of a free ALT flap using
Handheld Doppler localization the anterior approach as described by Song et al. and
[6]
All patients underwent preoperative perforator Koshima et al. Seven out of 10 patients in Group 1 and
[7]
localization using a handheld audible Doppler probe 9 out of 10 patients in Group 2 underwent subfascial
(Huntleigh Healthcare, 8 MHz, Cardiff, UK) performed by dissection while suprafascial dissection was performed in
an independent assessor who was blinded to the MDCTA the remainder of cases. During flap harvest, the location of
findings. The patient was placed in the supine position each cutaneous perforator was marked with a needle at a
with the leg straight in a neutral position. A line was drawn specified distance from the perforator through the fascia
Plast Aesthet Res || Vol 3 || Issue 2 || Feb 29, 2016 53