Applications
Dual energy CT has a wide range of clinical applications, and our lab uses it regularly to enhance diagnostic clarity across multiple areas. Two common examples include characterizing kidney stones and identifying urate crystal deposits in cases of suspected gout, both of which benefit from dual energy’s ability to distinguish materials that appear similar on standard CT.
Gout
Gout is a type of inflammatory arthritis caused by a buildup of uric acid crystals in the joints and surrounding tissues. These deposits trigger painful flares and long-term joint damage if left untreated. One of the key challenges in diagnosing gout is distinguishing uric acid crystals from other materials—particularly calcium deposits, which can appear similar on standard CT scans. This distinction is critical, as treatments for gout differ significantly from those used for calcium-based conditions like pseudogout or calcific tendinitis. Without a clear diagnosis, patients may receive the wrong treatment or face delays in care.
Dual energy CT addresses this problem by capturing images at two different X-ray energy levels. Because uric acid and calcium absorb X-rays differently depending on the energy, DECT can separate the two and highlight urate deposits directly on the images. This gives clinicians a non-invasive way to confirm gout, especially in difficult cases where fluid aspiration isn’t possible. DECT can also measure the total volume of crystal burden, allowing physicians to track how well urate-lowering therapies work over time. By improving both diagnosis and disease monitoring, DECT supports more accurate, tailored treatment for patients with gout.
Figure A: Dual energy CT images of the foot, to be used for identifying gout.
Figure B: The images of the foot from Figure A after post-processing filters have been applied, highlighting the presence of urate crystals in purple and calcified structures in green.
Figure C: Volume rendering of the imaging from Figure B, demonstrating the extent of urate crystal and calcified structures in 3D.
Kidney Stones
Kidney stones are hard mineral deposits that form in the kidneys and can cause severe pain, bleeding, or infection when they obstruct the urinary tract. Treatment depends heavily on the type of stone, as different compositions respond to different therapies. For example, uric acid stones can often be dissolved with medication, while calcium-based stones typically require physical removal. Standard CT is excellent at detecting stones, but it cannot reliably tell one type from another, leaving clinicians to rely on guesswork or post-removal analysis.
Dual energy CT offers a major improvement by allowing radiologists to identify stone composition non-invasively. By capturing images at two X-ray energy levels, it distinguishes uric acid from calcium and other stone types based on their material-specific attenuation patterns. This helps guide treatment from the start, determining whether a patient may benefit from medical management or needs surgical intervention. It can also reduce the need for repeat imaging or exploratory procedures. For patients with recurrent stones, DECT provides valuable insight into stone behavior over time, supporting more personalized prevention strategies.
Figure D: Axial dual energy CT images of the abdomen, used for analyzing the composition of kidney stones.
Figure E: The axial images of the abdomen from Figure D, now processed to analyze the composition of the kidney stone (indicated by the arrow).
Figure F: Processed images from Figure E, showing graphics that detail the stone’s size, volume, and composition.
