This study will investigate the tumor-associated vasculature of patients with peritoneal carcinomatosis, or cancer that spreads along the inner abdominal lining. The investigators will use a technology known as intravital microscopy (IVM) in order to visualize in real-time the tumor-associated vessels of peritoneal disease. The IVM observations may determine if an individual patient's tumor vessels would be amenable to receiving systemic therapy, based on the functionality of the vessels.

Primary objective(s): To determine the feasibility and clinical utility of performing HIVM in patients with peritoneal carcinomatosis during standard course of treatment (cytoreductive surgery with hyperthermic intraperitoneal chemotherapy, or CRS-HIPEC).

Secondary objective(s):

1. Compare the microscopic observation of the tumor-associated vessels with normal tissue (peritoneal surface) in each individual subject.
2. Correlate the microscopic observations of the tumor-associated vessels with pathologic grade of tumor implants.
3. Correlate the microscopic observation of the microvasculature with tumor-specific and overall survival.

Inclusion Criteria:

1. Age ≥ 18 years of age.
2. Have an ECOG Performance Status of ≤ 2. Refer to Appendix C.
3. Have measurable disease in the peritoneum by direct visualization (visible lesion typically > 0.5 cm in maximal diameter).
4. Carcinomatosis that meets indications for CRS-HIPEC.
5. Subject must understand the investigational nature of this study and sign an Independent Ethics Committee/Institutional Review Board approved written informed consent form prior to receiving any study related procedure.
6. A negative skin-prick test to fluorescein.

Exclusion Criteria:

1. Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations.
2. Renal dysfunction as defined as a GFR < 45.
3. Liver dysfunction as defined by Child-Pugh score > 5, or LFT's 1.5x above normal range.
4. Any known allergy or prior reaction to fluorescein or ICG or a positive skin prick test to fluorescein.
5. Pregnant or nursing female subjects, determined preoperatively with a urine pregnancy test.
6. Unwilling or unable to follow protocol requirements.
7. Any condition which in the Investigators' opinion deems the patient unsuitable (e.g., abnormal EKG).
8. Any condition that excludes CRS-HIPEC as the standard of care for the patient.

This is an open-label, non-randomized, single center, study of IVM observation in conjunction with fluorescein and ICG in subjects with peritoneal carcinomatosis undergoing CRS-HIPEC.