What Is a Pelvic CT Scan?

The upper part of the pelvis is the large pelvis, and the lower part of the pelvis is the small pelvis. The pelvis is made up of left and right hip bones and condyles, coccyx, and bone connections between them. The human body is upright, the pelvis is tilted forward, and the anterior superior iliac spines on both sides are in the same coronal plane under the two pubic tubercle nodes.

The upper part of the pelvis is the large pelvis, and the lower part of the pelvis is the small pelvis. The pelvis is made up of left and right hip bones and condyles, coccyx, and bone connections between them. The human body is upright, the pelvis is tilted forward, and the anterior superior iliac spines on both sides are in the same coronal plane under the two pubic tubercle nodes.

Chinese name

Large pelvis

Foreign name

Large pelvis

Features

Closely related to pregnancy and childbirth

Function

Protects the organs in the pelvis

Anatomy of the Great Pelvis and Pelvis

The pelvis can be formed by the arched line, the pubic comb, the pubic tubercle, and the pubic symphysis to the upper edge of the pubic symphysis. It is divided into a large pelvis or pseudopelvis above, and a small pelvis or true pelvis below. .

The large pelvis is made up of the metatarsal wings and metatarsals above the boundary. Because the pelvis is inclined forward, the large pelvis has almost no anterior wall.

The small pelvis, which is a stenosis of the pelvis that extends downward, can be divided into the upper pelvis, the lower pelvis, and the upper pelvis. The pelvis is surrounded by the above boundary line and is round or oval. The lower pelvis is surrounded by the tip of the coccyx, the sacral nodule ligament, the ischial tuberosity, the ischial branch, the pubic branch, and the inferior margin of the pubic bone. The sciatic branch and the inferior branch of the pubic bone are connected to form a pubic arch. The angle between them is called the inferior pubic angle. The cavity above and below the pelvis is called the pelvic cavity. The small pelvic cavity, also known as the intrinsic pelvic cavity, contains the rectum, bladder, and some reproductive organs. The small pelvic cavity is a curved channel with a short anterior wall and a long lateral diaphragm and a posterior wall. When the axis is the pelvic axis, the fetus is delivered along this axis.

The pelvis is a bony component between the trunk and free lower extremity bones. It plays the role of transmitting gravity and supporting and protecting the pelvic organs. When the human body is upright, the body weight is transmitted from the fifth lumbar vertebra, the sacrum through the sacroiliac joints on both sides, and the acetabulum to the femoral heads on both sides: the bow-shaped force transmission line from the femoral head down to the lower limbs is called the femoro-condylar arch. When a person is in the sitting position, gravity is transmitted from the sacroiliac joint to the ischial tuberosity on both sides. This arch-shaped force transmission is called the situs arch. There are also two restraining bows at the front of the pelvis to prevent the two bows from separating to the sides. One line connects the superior branches of the pubic bone at the joint of the pubic bone to prevent the femoro-condylar arch from being squeezed. The other is the pubic arch connected by the pubic bones on both sides and the ischial branch, which can restrain the zygomatic arch from spreading. The restraint bow is not as strong as the gravity bow. In trauma, the superior pubic branch of the restraint bow is more likely to fracture than the lower branch.

The position of the pelvis can vary depending on the posture of the human body. When the human body is upright, the pelvis tilts forward, and the plane of the pelvic upper mouth and the horizontal plane form an angle of about 50 ° to 55 ° (60 ° for women), which is called pelvic tilt. The increase and decrease of the pelvic inclination will affect the curvature of the spine. If the inclination increases, the center of gravity will advance, which will inevitably lead to lumbar lordosis. Otherwise, the waist curve decreases.

The poor sex of the pelvis is most pronounced in the human body's bones, and even the femoral pubic arch is obviously shy. The poor sex of the pelvis is related to its function. Although the main function of the pelvis is exercise, the female pelvis also needs to be suitable for childbirth. Therefore, the shape of the female pelvis is short and wide, and the upper pelvic opening is approximately round and wide. The lower pelvic opening and the subpubic angle are larger. The subpubic angle can reach 90 ° -100 ° for women, and 70 ° -75 ° for men.

CT Clinical application of large pelvic spiral CT reconstruction in pelvic fractures

Multi-slice spiral CT reconstruction is a new imaging technique. It uses special image processing software configured on the imaging workstation of the CT scanning system to process the original image data collected by the CT scan and reproduce the image according to the clinical diagnosis needs.

MPR, SSD and VR reconstruction images clearly show the details of pelvic fractures before surgery. The application of SSD, MPR, and VR technology has made a qualitative leap in imaging diagnosis of pelvic ring fractures. It can objectively, stereoscopically, clearly, and multi-anglely display the anatomical structure and subtle injuries of the pelvis and hip joints.The purpose is not only to find fractures, but also to solve complex anatomical parts that are not easily displayed by X-ray and CT (transverse scanning). Fractures, clarify the separation and displacement of fracture fragments and classification, and provide multiple images of the bone morphology and fracture morphology for clinicians through multi-angle observation of rotation technology. MPR can be imaged at multiple angles and at any angle. It is mainly used to observe the reconstructed images of the coronal, sagittal and arbitrary oblique planes, to understand the relationship between fracture sites and surrounding tissue damage in detail, especially the axial position cannot directly display the up-down relationship.

The three-dimensional sense of VR reconstruction space is strong, and the anatomical relationship is displayed clearly, which is conducive to the localization of the lesion. It can also be rotated 360 ° on any three-dimensional axis to achieve multi-directional and multi-angle observation of the entire pelvis and fractures. The position of the fixed needle and the reduction effect can be displayed visually in three dimensions. SSD uses surface covering technology to make stereo imaging a reality. It reflects the three-dimensional spatial information of bone structure. It shows the whole picture of fractures and dislocation joints, the direction of displacement of bone ends and the curved internal and external surfaces of the pelvis. The gross anatomy can visually display the pelvic structure, the location of the fracture line, the fracture line running, the extent of fracture involvement, the distance and angle of bone displacement, and the degree and extent of dislocation of the posterior wall of the pelvic joint.

Therefore, SSD has more special significance in assessing pelvic fractures: It can stereoscopically display the overall empty relationship of the pelvic flat bone fracture and easy to observe the pelvic rotation deformity; It can intuitively judge the degree of displacement fracture crushing, the shape of the broken bone fragments and Whether the stability of acetabular fractures is accompanied by flipping; can clearly show the morphological changes after acetabular and sacroiliac auricular articular surface fractures, the adaptation of the articular surface, and the integrity of the acetabular load-bearing dome. By comparison, the ability of MPR to show the direction and number of acetabular fracture lines is stronger than SSD and VR; the three-dimensional sense of SSD and VR images is strong, and the spatial position is clear. It can classify complex acetabular fractures and determine the direction of femoral head dislocation. And distance is better than MPR. In addition, VR reconstruction can also show the position of the fixed needle and the effect of reduction in three-dimensional visualization, which has a strong guiding effect on the evaluation of postoperative treatment.