Capabilities of magnetic resonance spectroscopy in detecting bowel metabolic disorders in critically ill patients: pilot results

In critically ill patients admitted to intensive care units (ICUs), monitoring the «target organ» – the intestines – becomes particularly important, as impaired intestinal function can exacerbate the underlying disease and contribute to the development of multiple organ failure.

Objective. To determine the capabilities of magnetic resonance spectroscopy (MRS) in detecting bowel metabolic disorders in critically ill patients.

Materials and methods. Thirty-two (32) critically ill patients hospitalized in the ICU of the «Clinical Hospital No. 1» in Smolensk underwent magnetic resonance imaging (MRI) of the bowel. The examination followed a standard protocol for magnetic resonance imaging of the abdomen, with the mandatory inclusion of proton magnetic resonance spectroscopy ('H-MRS) for the major metabolites of the intestinal wall. The comparison group included twenty-one (n=21) healthy volunteers without any gastrointestinal diseases. The following major metabolites of the intestinal wall were assessed using MRS: choline, creatine, lipids, glutamine/glutamate, citrate, lactate, aspartate, and N-acetylaspartate (NAA).

Results. The MRS-detected decrease in the concentration of choline, creatine, and lipids in the intestinal wall within 24–48 hours leads to an imbalance in the redox balance of the critically ill macroorganism, which triggers the development or progression of hepatocellular failure. For predicting the development of paralytic ileus or visceral hypersensitivity in patients during the early postoperative period, a «scissors effect» was evaluated: an increase in citrate levels with negative lactate levels indicates paralytic ileus; the opposite pattern indicates visceral hypersensitivity.

Conclusion. Pilot study confirmed that magnetic resonance spectroscopy (MRS) is a highly informative method for the early diagnosis of bowel metabolic disorders in critically ill patients. A decrease in the levels of choline, creatine, and lipids in the intestinal wall is detected within the first hours of admission to the ICU. A differential «scissors effect» (citrate/lactate ratio) was identified, enabling differentiation between paralytic ileus and visceral hypersensitivity (AUC=0.94). The dynamics of N-acetylaspartate serve as a marker of impaired oxidative homeostasis. The methodology, based on a standard MRI protocol, allows for a transition to the targeted correction of the identified metabolic deficiencies.

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