History
An 80-year-old male patient, complaining of chest discomfort, shortness of breath and lower limb edema, came to the hospital for a checkup. A Dual Energy (DE) CT angiography (CTA), followed by a dynamic 4D CTA were performed for evaluation.
Diagnosis
CTA images revealed an isolated aneurysm in the right common iliac artery (RCIA). It extended from the aortic bifurcation to the proximal right external iliac artery (REIA), with a maximum diameter of 4.1 cm. Severe stenoses in the proximal left renal artery (LRA) and the left internal iliac artery (LIIA) were seen. Extensive calcified plaques in multiple abdominal and peripheral arteries, causing mild to moderate stenoses, were also visualized. Peripheral artery insufficiency was ruled out by dynamic 4D CTA however severe stenosis in the right posterior tibial artery (RPTA), caused by calcified plaques, was confirmed. Subsequent percutaneous implantation of endovascular stent-grafts was successfully performed in the aortic bifurcation and in the proximal LRA, and the patient’s symptoms were significantly improved.
Fig. 1:
A cinematic VRT image shows an overview of the complete scan range.
Fig. 2:
MPR images show an aneurysm in the RCIA extending from the aortic bifurcation to the proximal REIA. A severe stenosis of the left renal artery is also seen (Fig. 2b, arrow).
Fig. 3:
Right-posterior views of pre- (Fig. 3a, cVRT; Fig. 3b, MIP) and post (Fig. 3c, MIP) stenting show an ectatic RCIA, severely stenosed LRA and LIIA, as well as stent grafts in the aortic bifurcation and in the proximal LRA (Fig. 3c, arrow).
Fig. 4:
A comparison of inverted MIP images (at the same windowing) derived from mixed image (Fig. 4a), mono+50 keV image (Fig. 4b) and dynamic CTA image (Fig. 4c). The peripheral arteries in the lower limbs are best shown in the dynamic 4D CTA, confirming a severe stenosis in the RPTA (arrow).
Comments
Isolated aneurysms in the iliac arteries are uncommon and may lead to peripheral artery insufficiency in the lower limbs. Appropriate candidate selection, for endovascular or surgical therapy, greatly relies on imaging classifications. Runoff CTA is usually performed. And DE allows automatic bone removal, as well as significant enhancement of vascular details using “syngo. CT DE Monoenergetic Plus”. However, if the peripheral arteries in the lower limbs are not well shown in DE CTA images, such as in this case, a critical question can be raised – does this indicate peripheral artery insufficiency or missing the bolus? Dynamic 4D CTA is performed using Adaptive 4D Spiral scanning to acquire images at multiple time points with defined intervals. This makes wrong bolus timing highly unlikely. Peripheral arteries are clearly demonstrated using the fused temporal maximum intensity projections (tMIP), which improves diagnostic confidence and helps the physicians making an appropriate treatment plan.