Imaging modalities for diagnosis and monitoring of cancer cachexia

Abstract

Cachexia, a multifactorial wasting syndrome, is highly prevalent among advanced-stage cancer patients. Unlike weight loss in healthy humans, the progressive loss of body weight in cancer cachexia primarily implicates lean body mass, caused by an aberrant metabolism and systemic inflammation. This may lead to disease aggravation, poorer quality of life, and increased mortality. Timely detection is, therefore, crucial, as is the careful monitoring of cancer progression, in an effort to improve management, facilitate individual treatment and minimize disease complications. A detailed analysis of body composition and tissue changes using imaging modalities-that is, computed tomography, magnetic resonance imaging, (¹⁸F) fluoro-2-deoxy-D-glucose (¹⁸FDG) PET and dual-energy X-ray absorptiometry-shows great premise for charting the course of cachexia. Quantitative and qualitative changes to adipose tissue, organs, and muscle compartments, particularly of the trunk and extremities, could present important biomarkers for phenotyping cachexia and determining its onset in patients. In this review, we present and compare the imaging techniques that have been used in the setting of cancer cachexia. Their individual limitations, drawbacks in the face of clinical routine care, and relevance in oncology are also discussed.

Keywords: Adipose tissue; Cancer cachexia progression; Computed tomography (CT); Imaging biomarkers; Imaging-based phenotyping; Magnetic resonance imaging (MRI); Skeletal muscle.

Fig. 1

Schematic highlighting cancer cachexia as a multi-organ syndrome: Cancer cachexia is regulated by signals that are released from the primary tumor, but also by mechanisms initiated by the host response. These pathways involve a wide range of organs, of which the main ones are indicated here. While the classical cachexia organs such as skeletal muscle and the fat depots have been in focus for quite some time, other major tissues such as the liver, the heart, the gut, and the brain are now known to be impacted or involved (as listed by the bullet points) in this syndrome, and are making their way into the spotlight

Fig. 2

Schematic showing the possible MRI biomarkers extracted from an abdominal chemical shift encoding-based water-fat separation MR imaging acquisition, including the determination SAT/VAT volume, ectopic lipid content in the liver and pancreas, paraspinal muscle volume and intramuscular fat content and adipose tissue lipid content

Fig. 3

Skeletal paraspinal muscle changes in a patient with cancer cachexia: axial abdominal MRI scan of a 74 year-old patient with squamous cell carcinoma of the esophagus at baseline (left image) and follow-up after 335 days (right image). Relative muscle volume change was − 19.9% for the erector spinae and − 26.3% for the psoas muscle. Relative change of contractile tissue volume was − 19.4% in erector spinae muscle and 25.3% in psoas muscle. Relative change in fat volume was − 21.2% in erector spinae muscle and 27.7% in psoas muscle. Absolute PDFF (%) difference was 0.5 in erector spinae muscle and 1.3 in the psoas muscle. BMI decreased from 24.1 to 21.1 kg/m². BMI body mass index, PDFF proton density fat fraction

Fig. 4

Adipose tissue changes in a patients with cancer cachexia: axial abdominal MRI images of a 54 year-old male subject with esophageal cancer at baseline (A) and follow-up after 8 months (B). A1, B1 Color-coded are VAT (green), SAT (blue) and non-adipose tissue (red). A2, B2 Corresponding PDFF maps showed a decrease in VAT from 83 to 72% and SAT from 87 to 76%. The BMI decreased from 30.2 to 24.1 kg/m2. BMI body mass index, PDFF proton density fat fraction, VAT visceral adipose tissue, SAT subcutaneous adipose tissue