Neck fat compartments in obesity

In a recent publication in the American Journal of Clinical Nutrition, Martin Torriani et al. used whole-body CT imaging to show that fat accumulation in the neck is correlated with cardiovascular risk and has different patterns in men and women. Further, neck fat accumulation involved specific neck compartments as adiposity increases. Read more here.

(A) Anatomic compartments of the neck at the level of C5. Tracings delimit subcutaneous (NATsc), posterior (NATpost), and perivertebral (NATperivert) compartments. (B) NAT compartments in a lean female without metabolic syndrome (27 years, BMI 23 kg/m2). (C) NAT accumulation in an obese female with metabolic syndrome (61 years, BMI 30 kg/m2).

(A) Anatomic compartments of the neck at the level of C5. Tracings delimit subcutaneous (NATsc), posterior (NATpost), and perivertebral (NATperivert) compartments. (B) NAT compartments in a lean female without metabolic syndrome (27 years, BMI 23 kg/m2). (C) NAT accumulation in an obese female with metabolic syndrome (61 years, BMI 30 kg/m2).

T2 mapping of adipose tissue fibrosis

IFP_T2map_combo

Panels A and B show a non-operated knee, with normal appearance of the infrapatellar fat and corresponding T2 map. Panels C and D are from the contra-lateral operated knee, with fibrosis (arrow) and T2 map showing lower values.

In a recent study by our group, Torriani and collaborators showed T2 mapping of infrapatellar adipose tissue was sensitive to detect fibrotic changes from arthroscopic surgery. This is a first step in quantitative assessment of adipose tissue fibrosis and future studies will perform T1rho and T2* adipose tissue relaxometry to further develop this research.

Fibrosis is an important feature of adipose tissue in obesity. Divoux et al. found that adipose tissue fibrosis limits omental adipocyte hypertrophy and hampers subcutaneous fat mass loss induced by bariatric surgery.

Relationship between lateral plantar process and peroneal tubercle

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(a) Photograph of a modern human calcaneus in lateral view with locations of the peroneal tubercle (straight arrow), retrotrochlear eminence (thin arrow), and lateral plantar process (curved arrow). (b) Photograph of a modern human calcaneus in axial view with location identified of the peroneal tubercle (straight arrow).

Gill and colleagues used magnetic resonance imaging (MRI) of the foot to determine a positive relationship between the size of the lateral plantar process and the peroneal tubercle in the human calcaneus. This study refuted observations made over the past 80 years and clarified evolutionary and biomechanical implications within the human lineage and fossil record.

This study highlights our multi-disciplinary and multi-institutional work in various scientific research fields. Feel free to contact us for possible collaborative opportunities!

Brown adipose tissue has a positive effect on bone

BAT_bone_combo

Quantification of brown adipose tissue (BAT) within red region of interest. BAT in the supraclavicular region shows as dark nodular areas of increased activity in PET (Panel A) that correspond to orange areas in fused PET/CT (Panel B).

Investigators from our group, including Miriam Bredella and Corey Gill, performed a study in adults that measured brown adipose tissue (BAT) by 18F-FDG positron emission tomography/computed tomography and found it is a positive predictor of femoral bone structure, correlating with thigh muscle and subcutaneous fat.

This work expands that by Ponrartana et al., who found a similar positive relationship between BAT volume and bone cross sectional area in children. Given that the pediatric population is more likely to have higher quantities of BAT, our work suggests this positive relationship between BAT and bone also remains influential in adults.

Ectopic and serum lipids are associated with marrow fat in obesity

1H Magnetic resonance spectroscopy of bone marrow at L4 vertebrae shows lipid (1.3 ppm) and unsuppressed water (4.7 ppm) resonances. Both spectra are from BMI-matched subjects. Note the relatively elevated lipid peak in the left image, suggestive of increased bone marrow fat content and increased fracture risk.

1H Magnetic resonance spectroscopy of bone marrow at L4 vertebrae shows lipid (1.3 ppm) and unsuppressed water (4.7 ppm) resonances. Both spectra are from BMI-matched subjects. Note the relatively elevated lipid peak in the left image, suggestive of increased bone marrow fat content.

In a study in the journal Radiology, Bredella and colleagues used 1H-MRS to quantify bone marrow fat content, intramyocellular lipids and intrahepatic lipids, concluding that ectopic and serum lipids are positively associated with bone marrow fat in obese men and women.

Because bone marrow fat is known to be inversely related to BMD, these results support the notion that ectopic and serum lipid levels are influenced by the same additional factors as bone marrow or may exert negative effects on bone.