Radiomics and anaesthetic planning: Quantitative imaging as a new frontier in preoperative risk assessment

Table 3 Computed tomography-derived body composition parameters and their anaesthetic implications

Parameter	Measurement method	Diagnostic threshold	Anaesthetic/perioperative significance
Skeletal Muscle Index	L3 axial CT area/height2	< 52.4 cm2/m2 (M), < 38.5 cm2/m2 (F)	Reduced physiologic reserve; prolonged recovery; increased ICU stay; altered drug metabolism
Skeletal muscle density	Mean HU of skeletal muscle at L3	< 41 HU (BMI < 25), < 33 HU (BMI ≥ 25)	Myosteatosis; worse perioperative morbidity and mortality than sarcopenia alone
Visceral adipose tissue	Area within peritoneal cavity at L3 (HU: -150 to -50)	≥ 100 cm2	Increased volume of distribution for lipophilic anaesthetics; technical difficulty with neuraxial/regional blocks
Subcutaneous adipose tissue	Area outside muscle fascia at L3	Context-dependent	Needle length considerations for regional anaesthesia; injection site planning
V/S ratio	VAT/SAT	> 0.4 (metabolic risk)	Metabolic syndrome; increased cardiovascular perioperative risk; insulin resistance
Psoas Muscle Index	Bilateral psoas area/height2	Population-specific	Frailty surrogate; postoperative mortality predictor (HR 2.15)

CT: Computed tomography; HU: Hounsfield units; BMI: Body mass index; ICU: Intensive care unit; M: Male; F: Female; L3: Third lumbar vertebra; VAT: Visceral adipose tissue; SAT: Subcutaneous adipose tissue; HR: Hazard ratio.