Screening for abdominal aortic aneurysms during routine lumbar CT scan: modification of the standard technique.

Introduction: Abdominal aortic aneurysms (AAAs) are often incidental findings in patients undergoing US, CT or MRI studies. The recommended field of view (FOV) for standard CT examinations of the spine is 14 cm. This FOV does not allow full visualization of the abdominal aorta.

Purpose: To justify a larger FOV for male smokers older than 55 years and women older than 65 years, with a higher incidence of AAA.

Materials And Methods: The lumbar CT examinations of 100 consecutive patients (age: mean 68 years, range 55-85 years) presented with low-back pain were retrospectively reviewed. Measurements of the abdominal aorta and lumbar abnormalities were analysed. A control study in 850 patients who underwent abdominal CT scans for other causes was available for comparison.

Results: There were three men with AAAs measuring 4.5, 5.5 and 5.6 cm (mean 5.2 cm). Findings related to the clinical problem were disk prolapse or herniation, spondylosis, spinal stenosis and grade I spondylolesthesis. In the control group, 17 patients were found with AAAs with diameter greater than 4 cm (2%).

Conclusions: Patients with low-back pain, older than 55 years of age, examined with lumbar spine CT, should also be screened for aortic disease, since the prevalence of AAA is similar with that of an age-matched control group. Appropriate modification in the applied FOV is recommended.