The Effects of Indocyanine Green Angiography (IGA) on Deep Inferior Epigastric Artery Perforator (DIEP) Flap Design and Post-Operative Fat Necrosis

For many post-mastectomy cancer patients seeking breast reconstruction, microsurgical,
autologous tissue transfer is a desirable alternative to more conventional, implant-based
procedures. In general terms, this technique entails use of one's own tissue, transferred
from a distant anatomic site, to recreate the absent breast. This tissue, usually a
composite of skin and subcutaneous adipose tissue, is isolated along with its source artery
and vein, and transferred to the chest wall where it is connected (anastomosed) to a local
blood supply.

Though there have been many donor tissues (flaps) described for this purpose, abdominal
tissue supplied by small, perforating blood vessels originating from the deep inferior
epigastric artery, has become the microsurgical gold standard. This so-called DIEP flap
provides abundant tissue that can be easily sculpted to fill most breast defects with
minimal donor site morbidity. Like all microvascular, free tissue transfers, however, the
DIEP flap is not without its potential complications. One potential complication that is
most distressing to patients occurs when a portion of the subcutaneous adipose tissue
transferred exceeds the available blood supply. This devascularized fat eventually undergoes
necrosis that may not only complicate the interpretation of future mammograms, but may
result in palpable, painful, and occasionally visible, irregularities within the transferred
tissue. Though many techniques/interventions/technologies have been described to minimize
the incidence of fat necrosis, its occurrence remains frustratingly unpredictable and
relatively common, with published rates ranging between 6 and 17 %.

In theory, maximizing perfusion to composite tissue flaps should minimize the rate of fat
necrosis. As such, many techniques have emerged in DIEP flap surgery intended to maximize
perfusion. One common technique is the use of pre-operative, CT angiography (CTA) to
identify the largest and most anatomically favorable perforating vessels to include in the
composite tissue transferred. Though elegant in its simplicity, use of this technique has
never been demonstrated to decrease the rate of fat necrosis in DIEP reconstructions. In
recent years, however, another technology intended to intra-operatively evaluate tissue
perfusion has emerged that may prove very beneficial in the realm of microvascular free
tissue transfer- Indocyanine green angiography (IGA).

IGA refers to the peripheral venous injection of lyophilized indocyanine green, a contrast
agent that fluoresces when excited by a laser of specific wavelength A charge-coupled
camera, held above the tissue of interest, can then detect the stimulated fluorescence and
project an image of "real-time" tissue perfusion that is proportional to emission intensity.
The application of IGA technology in reconstructive plastic surgery, a discipline that
relies largely on immediate and accurate assessment of tissue perfusion, has recently
generated much discussion.

We believe that perforator selection in DIEP breast reconstructions, a process traditionally
dictated at our institution by pre-operative CTA, may be heavily influenced by
intra-operative IGA. We further hypothesize that use of intra-operative IGA in DIEP breast
reconstructions may reduce the incidence of post-operative fat necrosis.

The aim of this study is to prospectively evaluate the effect of intra-operative Indocyanine
Green Angiography (IGA) on both flap design and rate of post-operative fat necrosis in
patients undergoing autologous breast reconstruction utilizing the Deep Inferior Epigastric
Artery Perforator (DIEP) flap.

Inclusion Criteria:

1. Female patients at the University of Washington

2. Aged twenty-five to sixty-five years

3. Pursuing immediate or delayed, DIEP-based, autologous, microsurgical breast
reconstruction at the University of Washington Medical Center

Exclusion Criteria:

1. Patients unsuitable for autologous, microsurgical breast reconstruction utilizing the
DIEP flap - i.e. patients who have undergone prior extensive abdominal surgeries,
have inadequate abdominal tissue bulk, who cannot comply with standardized
post-operative restrictions / assessments or patients afflicted with a medical
condition(s) precluding prolonged general anesthesia and surgery.

2. Patients who have a known allergy to contrast media will also be excluded from this
study.

3. Patients unable to read and write in English will be excluded.