The psoas muscle, a deep-seated muscle within the core, plays a significant role in movement and stability. When issues arise within this muscle or the surrounding area, a Computed Tomography (CT) scan often becomes a valuable diagnostic tool. This advanced imaging technique allows healthcare providers to visualize the muscle’s structure and identify various underlying conditions. Understanding what a psoas muscle CT scan shows can help clarify its importance in diagnosing a range of medical concerns.
Understanding the Psoas Muscle and CT Scans
The psoas major muscle originates from the lower thoracic and lumbar vertebrae, extending downwards through the pelvis before inserting onto the lesser trochanter of the femur. This deep anatomical positioning makes it a powerful hip flexor, contributing significantly to walking, running, and maintaining upright posture. The psoas muscle often works in conjunction with the iliacus muscle, forming what is known as the iliopsoas complex.
A Computed Tomography (CT) scan is a non-invasive medical imaging procedure that uses specialized X-ray equipment to produce detailed cross-sectional images of the body. Unlike a conventional X-ray, which provides a single flat image, a CT scanner rotates around the patient, taking numerous X-ray images from different angles. A computer then processes these images to create detailed slices, or “tomograms,” of bones, soft tissues, and blood vessels. CT is effective for visualizing the psoas muscle, given its deep location among abdominal and pelvic structures.
Reasons for a Psoas CT Scan
Healthcare providers often order a psoas muscle CT scan when specific symptoms or clinical findings suggest a potential issue within or around this deep muscle:
Persistent or unexplained pain in the hip, groin, lower back, or thigh is a common indication, especially if the pain radiates or does not respond to initial treatments. This type of pain can sometimes be aggravated by movement involving hip flexion.
The presence of a fever of unknown origin, particularly when accompanied by abdominal discomfort or a limp, might also prompt a CT scan to investigate for potential infections.
A doctor might also order a scan if they detect a palpable mass during a physical examination of the abdomen or pelvis.
Unexplained weakness in the leg or difficulty with walking that suggests a problem with the hip flexors can be a reason to perform this imaging.
Conditions Revealed by Psoas CT
A psoas muscle CT scan provides detailed images that can effectively diagnose several conditions affecting this deep muscle:
Psoas Abscess: A common finding is a collection of pus within the muscle sheath. These can be primary, arising spontaneously without an obvious source, or secondary, resulting from the spread of infection from nearby structures like the spine, bowel, or kidneys. The CT scan is highly accurate in detecting these abscesses, showing fluid collections with enhancing walls, and can also guide percutaneous drainage procedures.
Hematoma: A collection of blood within the muscle tissue. These often occur due to trauma, such as a direct blow or a fall, but can also arise spontaneously in individuals taking anticoagulant medications, presenting as a dense, well-defined mass within the muscle.
Muscle Tears or Strains: While frequently diagnosed clinically, a CT scan can confirm severe cases, particularly if there is significant swelling, or help exclude other pathologies mimicking a tear.
Tumors: The scan can also identify primary sarcomas originating in the muscle or metastatic lesions that have spread from other parts of the body, appearing as abnormal masses with varying densities.
Inflammation: Myositis (muscle inflammation) or tendinitis (tendon inflammation) can also be seen on CT, presenting as muscle enlargement, subtle fluid collections, or changes in tissue density.
Other Retroperitoneal Pathologies: Such as enlarged lymph nodes (lymphadenopathy) or other masses that might be impinging upon or displacing the psoas muscle, contributing to the patient’s symptoms.
Preparing For and Undergoing a Psoas CT
Preparing for the Scan
Preparing for a psoas muscle CT scan involves specific instructions for clear images. Patients are often advised to fast for several hours before the procedure, usually four to six hours, especially if contrast material is administered. It is important to inform the medical staff about any allergies, particularly to iodine-based contrast dyes, or any kidney problems, as these can affect contrast use. Disclose all current medications and any possibility of pregnancy.
During the Scan
During the CT scan, the patient lies on a motorized table that slides into a large, doughnut-shaped scanner. The machine rotates around the patient, capturing X-ray images. Remaining very still avoids blurring images, and the technologist may ask the patient to hold their breath briefly. Intravenous contrast material, injected into a vein, helps highlight blood vessels and organs, making abnormalities more visible.
After the Scan
The procedure usually takes 10 to 30 minutes, depending on the area scanned and whether contrast is used. After the scan, patients can typically resume normal activities unless otherwise instructed.