title: Evaluation of hyperspectral technology for assessing the presence and severity of peripheral artery disease.
abstract: BACKGROUND
  Hyperspectral imaging is a novel technology that can noninvasively measure oxyhemoglobin and deoxyhemoglobin concentrations to create an anatomic oxygenation map. It has predicted healing of diabetic foot ulcers; however, its ability to assess peripheral arterial disease (PAD) has not been studied. The aims of this study were to determine if hyperspectral imaging could accurately assess the presence or absence of PAD and accurately predict PAD severity.
  
  
  METHODS
  This prospective study included consecutive consenting patients presenting to the vascular laboratory at the Jesse Brown VA Medical Center during a 10-week period for a lower extremity arterial study, including ankle-brachial index (ABI) and Doppler waveforms. Patients with lower extremity edema were excluded. Patients underwent hyperspectral imaging at nine angiosomes on each extremity. Additional sites were imaged when tissue loss was present. Medical records of enrolled patients were reviewed for demographic data, active medications, surgical history, and other information pertinent to PAD. Patients were separated into no-PAD and PAD groups. Differences in hyperspectral values between the groups were evaluated using the two-tailed t test. Analysis for differences in values over varying severities of PAD, as defined by triphasic, biphasic, or monophasic Doppler waveforms, was conducted using one-way analysis of variance. Hyperspectral values were correlated with the ABI using a Pearson bivariate linear correlation test.
  
  
  RESULTS
  The study enrolled 126 patients (252 limbs). After exclusion of 15 patients, 111 patients were left for analysis, including 46 (92 limbs) no-PAD patients and 65 (130 limbs) PAD patients. Groups differed in age, diabetes, coronary artery disease, congestive heart failure, tobacco use, and insulin use. Deoxyhemoglobin values for the plantar metatarsal, arch, and heel angiosomes were significantly different between patients with and without PAD (P < .005). Mean deoxyhemoglobin values for the same three angiosomes showed significant differences between patients with monophasic, biphasic, and triphasic waveforms (P < .05). In patients with PAD, there was also significant correlation between deoxyhemoglobin values and ABI for the same three angiosomes (P = .001). Oxyhemoglobin values did not predict the presence or absence of PAD, did not correlate with PAD severity, and did not correlate with the ABI.
  
  
  CONCLUSIONS
  These results suggest the ability of hyperspectral imaging to detect the presence of PAD. Hyperspectral measurements can also evaluate different severities of PAD.
authors.affiliation: Division of Vascular Surgery, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Chin
authors.forename: Edward C
authors.initials: EC
authors.lastname: Wang
authors.forename: Melina R
authors.initials: MR
authors.lastname: Kibbe
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D035002:Lower Extremity / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D010108:Oxyhemoglobins / Q000378:metabolism*; D058729:Peripheral Arterial Disease / Q000175:diagnosis* / Q000378:metabolism; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D013057:Spectrum Analysis / Q000295:instrumentation
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin