Sternal foramina: An imaging study

To investigate the computed tomography (CT) image characteristics, adjacent tissues, and related measurement indices of the sternal foramina and provide an anatomical basis for the safety of minimally invasive sternum surgery. The data from 2500 thoracic multi-slice computed tomography (MSCT) cases from January 2020 to June 2021 were analyzed retrospectively. The number and location of the sternal foramina and adjacent tissues (mediastinal adipose tissue, lung, pericardium) were observed. The size of the sternal foramina, CT value of the tissue inside the foramina, subcutaneous adipose tissue thickness, distance from skin to lung, distance from skin to the pericardium, and manubrio-foraminal distance were measured. Sex differences were compared for each indicator performed. The incidence of sternal foramina was 4.44% (111/2500), with 83 males and 28 females. All sternal foramina were located at the mesosternum's fourth to sixth costal cartilage level. The transverse diameter of the sternal foramina was (0.60 ± 0.29) cm, and the vertical diameter was (0.68 ± 0.39) cm, which was greater in males than females (p > 0.01). The CT value of the tissue in the sternal foramina was (-77.05 ± 32.26) Hu, and there was no statistical difference between male and female patients (t = -1.780, p = 0.078). The adjacent tissues of the sternal foramina were only adjacent to adipose tissue in 41 cases (36.94%), pericardium in 18 patients (16.22%), lung tissue in 37 cases (33.33%), and both kinds of tissue in 15 cases (13.51%). The sternal foramina were not adjacent to the left lung in the female patients. In the sternal foramina region, the thickness of subcutaneous adipose tissue was (1.13 ± 0.51) cm, the distance from skin to lung was (1.86 ± 0.57) cm, the distance from skin to pericardium was (3.07 ± 0.72) cm, the manubrio-foraminal distance was (12.68 ± 1.31) cm, which was significantly greater in males than in females (p < 0.05). The sternal foramina are closely related to the heart and lungs. The size and location of sternal foramina, the thickness of subcutaneous adipose tissue, and the distance from skin to heart and lung are all crucial factors in evaluating the safety of sternal puncture biopsy.