Multispectral optoacoustic tomography of the human intestine - temporal precision and the influence of postprandial gastrointestinal blood flow

Multispectral optoacoustic tomography (MSOT) holds great promise as a non-invasive diagnostic tool for inflammatory bowel diseases. Yet, reliability and the impact of physiological processes during fasting and after food intake on optoacoustic signals have not been studied. In the present investigator initiated trial (NCT05160077) the intestines of ten healthy subjects were examined by MSOT at eight timepoints on two days, one fasting and one after food intake. While within-timepoint and within-day reproducibility were good for single wavelength 800 nm and total hemoglobin (ICC 0.722-0.956), between-day reproducibility was inferior (ICC -0.137 to 0.438). However, temporal variability was smaller than variation between individuals (coefficients of variation 8.9%-33.7% vs. 17.0%-48.5%). After food intake and consecutive increased intestinal circulation, indicated by reduced resistance index of simultaneous Doppler ultrasound, optoacoustic signals did not alter significantly. In summary, this study demonstrates high reliability and temporal stability of MSOT for imaging the human intestine during fasting and after food intake.

Intraoperative real-time fluorescence angiography with indocyanine green for evaluation of intestinal viability during surgery for an incarcerated obturator hernia: a case report

Background

Bowel incarceration represents a dreaded complication amongst patients with hernias. The intraoperative evaluation of the bowel perfusion following hernia reduction with regard to the need for resection of ischaemic bowel can be challenging. In this case report we discuss intraoperative fluorescence angiography with indocyanine green (ICG) as an objective means of accessing bowel perfusion following hernia reduction.

Case presentation

The case of a 92-year-old, caucasian, female patient presenting with symptoms of small bowel obstruction secondary to an incarcerated left sided obturator hernia is presented. An incarcerated segment of the small bowel was reduced during emergency laparoscopy. Intraoperative ICG fluorescence angiography revealed ischaemic changes in the normal appearing bowel, so that the involved segment was resected. The postoperative course was uneventful and the patient was discharged home safely on postoperative day seven.

Conclusion

Intraoperative ICG fluorescence angiography provides an objective method of judging bowel perfusion and therefore represents a useful tool for assessing intestinal perfusion in patients with incarcerated hernia.

Intestinal blood flow assessment by indocyanine green fluorescence imaging in a patient with the incarcerated umbilical hernia: Report of a case

After reduction of the incarceration during surgery for incarcerated hernia, intestinal blood flow (IBF) and the need for bowel resection must be evaluated. We report the case of a patient with incarcerated umbilical hernia in whom the bowel was preserved after evaluating IBF using indocyanine green (ICG) fluorescence. A woman in her 40s with a chief complaint of abdominal pain visited our hospital, was diagnosed with incarcerated umbilical hernia and underwent surgery. Laparotomy was performed to reduce bowel incarceration. After reducing the incarceration, IBF was observed using ICG fluorescence detected using a brightfield full-color fluorescence camera. The small bowel that had been incarcerated showed deep-red discoloration on gross evaluation, but intravenous injection of ICG revealed uniform fluorescence of the mesentery and bowel wall. This indicated an absence of irreversible ischemic changes of the bowel, so no resection was performed. The patient showed a good postoperative course, including resumption of eating on day 4 and discharge on day 11. In surgery for incarcerated hernia, ICG fluorescence may offer a useful method to evaluate IBF after reducing the incarceration. This case implied that PINPOINT could be used in open conventional surgery.

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We have reported the case of a patient with incarcerated umbilical hernia.

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The small bowel that had been incarcerated showed deep-red discoloration.

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The bowel could be preserved after intraoperative evaluation of intestinal blood flow.

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The intestinal blood flow was evaluated by ICG fluorescence.

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PINPOINT, a brightfield color fluorescence camera was used for ICG fluorescence.

Update on Colon Ischemia: Recent Insights and Advances

Colon ischemia (CI) is the most common manifestation of ischemic injury to the gastrointestinal (GI) tract. This usually self-limited disease is being diagnosed more frequently, and the list of known causes is increasing. Local hypoperfusion and reperfusion injury are both thought to contribute to the disease process, which manifests with a wide spectrum of injury including reversible colopathy (subepithelial hemorrhage and edema), transient colitis, chronic colitis, stricture, gangrene, and fulminant universal colitis. The distribution is usually segmental with left-sided disease (e.g., inferior mesenteric artery distribution) being more frequently observed than right-sided involvement (e.g., superior mesenteric artery distribution). Any portion of the colon can be affected, but the anatomic distribution of CI recently has been shown to be associated with outcome. Patients with isolated-right colon ischemia (IRCI) have a different presentation and worse outcomes than other distributions of disease. Although somewhat variable depending on disease location, CI presents with cramping abdominal pains over the segment of colon involved followed by a short course of bloody diarrhea. Diagnosis is usually made clinically and is supported with serologic, radiologic, and colonoscopic findings. Colonoscopy is the most accurate diagnostic study. Most patients respond to conservative supportive therapy although some with more severe disease require antimicrobials and/or surgical intervention.

Oral relaxin maintains intestinal blood flow in a rat model of NEC

PURPOSE

Intestinal vasoconstriction is a critical step in development of necrotizing enterocolitis (NEC). Relaxin (RLXN), a hormone found in breast milk but absent from formula, is a potent vasodilator. We hypothesized that relaxin-supplemented feeds with an NEC protocol would decrease NEC severity and increase intestinal blood flow.

METHODS

Timed-pregnant Sprague-Dawley rats were randomly assigned to CONTROL, NEC, NEC+1xRLXN, or NEC+All Feeds RLXN, and all but CONTROL underwent NEC protocol. NEC+1xRLXN and NEC+All Feeds RLXN groups were fed relaxin-supplemented formula with the last feed or every feed. At 48h of life, intestinal blood flow was measured at baseline and after application of 2.5% Delflex® solution.

RESULTS

The addition of relaxin to NEC group feeds (1x or All Feeds) improved the degree of ileal injury. Ileal blood flow was decreased in the NEC pups compared to the CONTROLS, but the addition of relaxin to one feed increased baseline ileal blood flow in the NEC group compared to NEC alone. Furthermore, the addition of relaxin to ALL feeds significantly increased baseline ileal blood flow.

CONCLUSION

Pups who received relaxin with all feeds had substantially increased ileal perfusion compared to control pups. Our data suggest that relaxin supplementation maintains intestinal blood flow and results in less histologic NEC.

Clinical features of ischemic colitis

Ischemic colitis (IC) is the most common form of ischemic injury of the gastrointestinal tract and occurs more frequently in the elderly. It presents either as an occlusive or a non-occlusive form of intestinal ischaemia. The clinical presentation of IC is variable and non-specific. Colonoscopy is the most common diagnostic method and the golden standard for confirmation of IC. Therapy and outcome depend on the severity and complications of the disease. Most cases of the non-gangrenous form show a favorable prognosis after conservative therapy, while high mortality and urgent operative intervention are the hallmarks of gangrenous IC.

Ischemic colitis: Clinical practice in diagnosis and treatment

Ischemic colitis is the most common form of ischemic injury of the gastrointestinal tract and can present either as an occlusive or a non-occlusive form. It accounts for 1 in 1000 hospitalizations but its incidence is underestimated because it often has a mild and transient nature. The etiology of ischemic colitis is multifactorial and the clinical presentation variable. The diagnosis is based on a combination of clinical suspicion, radiographic, endoscopic and histological findings. Therapy and outcome depends on the severity of the disease. Most cases of the non-gangrenous form are transient and resolve spontaneously without complications. On the other hand, high morbidity and mortality and urgent operative intervention are the hallmarks of gangrenous ischemic colitis.