In-stent Restenoses and Occlusion – a follow-up of Multiple Peripheral Arterial Stents

Pan Liu, MD; Yuquan Wang, MD; Xi Zhao*, MD; Rongpin Wang, MD
Department of Radiology, Guizhou Provincial People’s Hospital, Guiyang, P. R. China
*Siemens Healthineers China
|24/09/2019

A 79-year-old male patient, who had undergone vascular stenting due to severe stenoses in both lower extremities one year ago, was referred to our hospital for a follow-up. A Dual Energy (DE) runoff CT Angiography (CTA) was performed for evaluation.

CTA images showed multiple stents in the right external iliac artery, as well as bilaterally in the proximal and distal femoral arteries. A complete contrast filling defect was seen in the distal segment of the right proximal femoral stent, measuring 5.6 cm in length, indicating an occlusion. Collateral vessels allowed visualization of the circulation in the lower limb. Various degrees of lumen irregularity and narrowing caused by hypodense areas within the stents were seen in all stents, suggesting in-stent restenosis. Extensive calcified and noncalcified plaques were bilaterally demonstrated. Moderate stenoses bilaterally in the external iliac arteries, as well as severe stenoses in the middle segment of the left femoral artery, the left popliteal artery and the right femoral artery distal to the distal stent were visualized. The patient successfully underwent angioplasty.

A Dual Energy runoff CT angiography was performed on 79-year old male patient for a follow-up evaluation after vascular stenting.
Courtesy of Guizhou Provincial People’s Hospital, Guiyang, P. R. China

Fig. 1:
A cinematic VRT image shows an overview of bilateral multiple stents. A transparent distal segment of the proximal femoral stent indicates an occlusion.

A Dual Energy runoff CT angiography was performed on 79-year old male patient for a follow-up evaluation after vascular stenting.
Courtesy of Guizhou Provincial People’s Hospital, Guiyang, P. R. China

Fig. 2:
Inverted MIP images (Fig. 2a, 45 keV; Fig. 2b, 70 keV; same windowing) demonstrate the DSA-like views. Contrast enhancement is significantly improved showing more vascular details in the image displayed at 45 keV (Fig. 2a). Moderate stenoses bilaterally in the external iliac arteries, as well as severe stenoses (Fig. 2b, arrows) in the middle segment of the left femoral artery, the left popliteal artery and the right femoral artery distal to the distal stent are shown.

Arterial stenoses of the lower extremities are often treated with angioplasty and stents. One of the major problems of this procedure is in-stent restenosis. Although digital subtraction angiography (DSA) is the standard follow-up procedure, CT has been increasingly used in clinical practice as an alternative. In this case, a DE scan was performed using a special tin filter enabling significant separation of energy spectra at 70 and 150 kV settings. The attenuation measured at these two kV settings are used to display images at different keV levels using syngo.CT DE Monoenergetic Plus. Image contrast at 45 keV is significantly enhanced, allowing a clearer visualization of the vascular details. The bone structures can be removed using syngo.CT DE Direct Angio to show non-obscured vasculature. All evaluations are performed in an automated workflow. The image quality achieved is superb in providing a clear overview for the physicians to ensure a confident evaluation of the stents.

A Dual Energy runoff CT angiography was performed on 79-year old male patient for a follow-up evaluation after vascular stenting.
Courtesy of Guizhou Provincial People’s Hospital, Guiyang, P. R. China

Fig 3:
Curved MPR images (Fig. 3a, right side; Fig. 3b, left side) show the luminal views of the stents. A complete filling defect of the contrast in the distal segment of the right proximal femoral stent is seen (Fig. 3a, dotted arrow), indicating an occlusion. Various degrees of lumen irregularity and narrowing caused by hypodense areas within the stents are present suggesting in-stent restenoses.

Scanner

Scan area

Lower Extremities

Scan mode

Dual Source Dual Energy

Scan length

1045 mm

Scan direction

Cranio-caudal

Scan time

17 s

Tube voltage

70 / Sn150 kV

Effective mAs

123 / 43 mAs

Dose modulation

CARE Dose4D

CTDIvol

2.91 mGy

DLP

309.6 mGy cm

Rotation time

0.25 s

Pitch

0.4

Slice collimation

128 x 0.6 mm

Slice width

1.5 mm

Reconstruction increment

1.0 mm

Reconstruction kernel

Qr40

Contrast

370 mg/mL

Volume

75 mL + 25 mL + 40 mL saline

Flow rate

5 mL/s + 2 mL/s + 5 mL/s

Start delay

Bolus tracking in the abdominal aorta at the renal level with 120HU and an additional delay of 15 s